source: libcfa/src/heap.cfa @ db19e1d

//
// Cforall Version 1.0.0 Copyright (C) 2017 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// heap.cfa --
//
// Author           : Peter A. Buhr
// Created On       : Tue Dec 19 21:58:35 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Wed Aug  7 10:14:47 2024
// Update Count     : 1646
//

#include <stdio.h>
#include <string.h>                                                                             // memset, memcpy
#include <limits.h>                                                                             // ULONG_MAX
#include <errno.h>                                                                              // errno, ENOMEM, EINVAL
#include <unistd.h>                                                                             // STDERR_FILENO, sbrk, sysconf, write
#include <sys/mman.h>                                                                   // mmap, munmap
extern "C" {
#include <sys/sysinfo.h>                                                                // get_nprocs
} // extern "C"

#include "heap.hfa"
#include "bits/align.hfa"                                                               // libAlign
#include "bits/defs.hfa"                                                                // likely, unlikely
#include "concurrency/kernel/fwd.hfa"                                   // disable_interrupts, enable_interrupts
#include "startup.hfa"                                                                  // STARTUP_PRIORITY_MEMORY
#include "math.hfa"                                                                             // ceiling, min
#include "bitmanip.hfa"                                                                 // is_pow2, ceiling2

// supported mallopt options
#ifndef M_MMAP_THRESHOLD
#define M_MMAP_THRESHOLD (-1)
#endif // M_MMAP_THRESHOLD

#ifndef M_TOP_PAD
#define M_TOP_PAD (-2)
#endif // M_TOP_PAD

#define FASTLOOKUP                                                                              // use O(1) table lookup from allocation size to bucket size
#define OWNERSHIP                                                                               // return freed memory to owner thread
#define RETURNSPIN                                                                              // toggle spinlock / lockfree queue
#if ! defined( OWNERSHIP ) && defined( RETURNSPIN )
#warning "RETURNSPIN is ignored without OWNERSHIP; suggest commenting out RETURNSPIN"
#endif // ! OWNERSHIP && RETURNSPIN

#define CACHE_ALIGN 64
#define CALIGN __attribute__(( aligned(CACHE_ALIGN) ))

#define TLSMODEL __attribute__(( tls_model("initial-exec") ))

#define __STATISTICS__

enum {
        // The default extension heap amount in units of bytes. When the current heap reaches the brk address, the brk
        // address is extended by the extension amount.
        __CFA_DEFAULT_HEAP_EXPANSION__ = 10 * 1024 * 1024,

        // The mmap crossover point during allocation. Allocations less than this amount are allocated from buckets; values
        // greater than or equal to this value are mmap from the operating system.
        __CFA_DEFAULT_MMAP_START__ = 512 * 1024 + 1,

        // The default unfreed storage amount in units of bytes. When the uC++ program ends it subtracts this amount from
        // the malloc/free counter to adjust for storage the program does not free.
        __CFA_DEFAULT_HEAP_UNFREED__ = 0
}; // enum


//####################### Heap Trace/Print ####################


static bool traceHeap = false;

inline bool traceHeap() libcfa_public { return traceHeap; }

bool traceHeapOn() libcfa_public {
        bool temp = traceHeap;
        traceHeap = true;
        return temp;
} // traceHeapOn

bool traceHeapOff() libcfa_public {
        bool temp = traceHeap;
        traceHeap = false;
        return temp;
} // traceHeapOff

bool traceHeapTerm() libcfa_public { return false; }


static bool prtFree = false;

bool prtFree() {
        return prtFree;
} // prtFree

bool prtFreeOn() {
        bool temp = prtFree;
        prtFree = true;
        return temp;
} // prtFreeOn

bool prtFreeOff() {
        bool temp = prtFree;
        prtFree = false;
        return temp;
} // prtFreeOff


//######################### Helpers #########################


// CFA generic Bsearchl does not inline, so substitute with hand-coded binary-search.
inline __attribute__((always_inline))
static size_t Bsearchl( unsigned int key, const unsigned int vals[], size_t dim ) {
        size_t l = 0, m, h = dim;
        while ( l < h ) {
                m = (l + h) / 2;
                if ( (unsigned int &)(vals[m]) < key ) {                // cast away const
                        l = m + 1;
                } else {
                        h = m;
                } // if
        } // while
        return l;
} // Bsearchl


// pause to prevent excess processor bus usage
#if defined( __i386 ) || defined( __x86_64 )
        #define Pause() __asm__ __volatile__ ( "pause" : : : )
#elif defined(__ARM_ARCH)
        #define Pause() __asm__ __volatile__ ( "YIELD" : : : )
#else
        #error unsupported architecture
#endif

typedef volatile uintptr_t SpinLock_t;

static inline __attribute__((always_inline)) void lock( volatile SpinLock_t & slock ) {
        enum { SPIN_START = 4, SPIN_END = 64 * 1024, };
        unsigned int spin = SPIN_START;

        for ( unsigned int i = 1;; i += 1 ) {
          if ( slock == 0 && __atomic_test_and_set( &slock, __ATOMIC_ACQUIRE ) == 0 ) break; // Fence
                for ( volatile unsigned int s = 0; s < spin; s += 1 ) Pause(); // exponential spin
                spin += spin;                                                                   // powers of 2
                //if ( i % 64 == 0 ) spin += spin;                              // slowly increase by powers of 2
                if ( spin > SPIN_END ) spin = SPIN_END;                 // cap spinning
        } // for
} // spin_lock

static inline __attribute__((always_inline)) void unlock( volatile SpinLock_t & slock ) {
        __atomic_clear( &slock, __ATOMIC_RELEASE );                     // Fence
} // spin_unlock


//####################### Heap Statistics ####################


#ifdef __STATISTICS__
enum { CntTriples = 12 };                                                               // number of counter triples
enum { MALLOC, AALLOC, CALLOC, MEMALIGN, AMEMALIGN, CMEMALIGN, RESIZE, REALLOC, FREE };

struct StatsOverlay {                                                                   // overlay for iteration
        unsigned int calls, calls_0;
        unsigned long long int request, alloc;
};

// Heap statistics counters.
union HeapStatistics {
        struct {                                                                                        // minimum qualification
                unsigned int malloc_calls, malloc_0_calls;
                unsigned long long int malloc_storage_request, malloc_storage_alloc;
                unsigned int aalloc_calls, aalloc_0_calls;
                unsigned long long int aalloc_storage_request, aalloc_storage_alloc;
                unsigned int calloc_calls, calloc_0_calls;
                unsigned long long int calloc_storage_request, calloc_storage_alloc;
                unsigned int memalign_calls, memalign_0_calls;
                unsigned long long int memalign_storage_request, memalign_storage_alloc;
                unsigned int amemalign_calls, amemalign_0_calls;
                unsigned long long int amemalign_storage_request, amemalign_storage_alloc;
                unsigned int cmemalign_calls, cmemalign_0_calls;
                unsigned long long int cmemalign_storage_request, cmemalign_storage_alloc;
                unsigned int resize_calls, resize_0_calls;
                unsigned long long int resize_storage_request, resize_storage_alloc;
                unsigned int realloc_calls, realloc_0_calls;
                unsigned long long int realloc_storage_request, realloc_storage_alloc;
                unsigned int free_calls, free_null_0_calls;
                unsigned long long int free_storage_request, free_storage_alloc;
                unsigned int return_pulls, return_pushes;
                unsigned long long int return_storage_request, return_storage_alloc;
                unsigned int mmap_calls, mmap_0_calls;                  // no zero calls
                unsigned long long int mmap_storage_request, mmap_storage_alloc;
                unsigned int munmap_calls, munmap_0_calls;              // no zero calls
                unsigned long long int munmap_storage_request, munmap_storage_alloc;
        };
        struct StatsOverlay counters[CntTriples];                       // overlay for iteration
}; // HeapStatistics

static_assert( sizeof(HeapStatistics) == CntTriples * sizeof(StatsOverlay),
                           "Heap statistics counter-triplets does not match with array size" );

static void HeapStatisticsCtor( HeapStatistics & stats ) {
        memset( &stats, '\0', sizeof(stats) );                          // very fast
        // for ( unsigned int i = 0; i < CntTriples; i += 1 ) {
        //      stats.counters[i].calls = stats.counters[i].calls_0 = stats.counters[i].request = stats.counters[i].alloc = 0;
        // } // for
} // HeapStatisticsCtor

static HeapStatistics & ?+=?( HeapStatistics & lhs, const HeapStatistics & rhs ) {
        for ( unsigned int i = 0; i < CntTriples; i += 1 ) {
                lhs.counters[i].calls += rhs.counters[i].calls;
                lhs.counters[i].calls_0 += rhs.counters[i].calls_0;
                lhs.counters[i].request += rhs.counters[i].request;
                lhs.counters[i].alloc += rhs.counters[i].alloc;
        } // for
        return lhs;
} // ?+=?
#endif // __STATISTICS__


// Recursive definitions: HeapManager needs size of bucket array and bucket area needs sizeof HeapManager storage.
// Break recursion by hardcoding number of buckets and statically checking number is correct after bucket array defined.
enum { NoBucketSizes = 91 };                                                    // number of buckets sizes

struct Heap {
        struct Storage {
                struct Header {                                                                 // header
                        union Kind {
                                struct RealHeader {                                             // 4-byte word => 8-byte header, 8-byte word => 16-byte header
                                        union {
                                                // 2nd low-order bit => zero filled, 3rd low-order bit => mmapped
                                                // FreeHeader * home;                   // allocated block points back to home locations (must overlay alignment)
                                                void * home;                                    // allocated block points back to home locations (must overlay alignment)
                                                size_t blockSize;                               // size for munmap (must overlay alignment)
                                                Storage * next;                                 // freed block points to next freed block of same size
                                        };
                                        size_t size;                                            // allocation size in bytes
                                } real; // RealHeader

                                struct FakeHeader {
                                        uintptr_t alignment;                            // 1st low-order bit => fake header & alignment
                                        uintptr_t offset;
                                } fake; // FakeHeader
                        } kind; // Kind
                } header; // Header

                char pad[libAlign() - sizeof( Header )];
                char data[0];                                                                   // storage
        }; // Storage

        static_assert( libAlign() >= sizeof( Storage ), "minimum alignment < sizeof( Storage )" );

        struct CALIGN FreeHeader {
                #ifdef OWNERSHIP
                #ifdef RETURNSPIN
                SpinLock_t returnLock;
                #endif // RETURNSPIN
                Storage * returnList;                                                   // other thread return list
                #endif // OWNERSHIP

                Storage * freeList;                                                             // thread free list
                Heap * homeManager;                                                             // heap owner (free storage to bucket, from bucket to heap)
                size_t blockSize;                                                               // size of allocations on this list
        }; // FreeHeader

        FreeHeader freeLists[NoBucketSizes];                            // buckets for different allocation sizes
        void * heapBuffer;                                                                      // start of free storage in buffer
        size_t heapReserve;                                                                     // amount of remaining free storage in buffer

        #if defined( __STATISTICS__ ) || defined( __CFA_DEBUG__ )
        Heap * nextHeapManager;                                                         // intrusive link of existing heaps; traversed to collect statistics or check unfreed storage
        #endif // __STATISTICS__ || __CFA_DEBUG__
        Heap * nextFreeHeapManager;                                                     // intrusive link of free heaps from terminated threads; reused by new threads

        #ifdef __CFA_DEBUG__
        ptrdiff_t allocUnfreed;                                                         // running total of allocations minus frees; can be negative
        #endif // __CFA_DEBUG__

        #ifdef __STATISTICS__
        HeapStatistics stats;                                                           // local statistic table for this heap
        #endif // __STATISTICS__
}; // Heap


struct HeapMaster {
        SpinLock_t extLock;                                                                     // protects allocation-buffer extension
        SpinLock_t mgrLock;                                                                     // protects freeHeapManagersList, heapManagersList, heapManagersStorage, heapManagersStorageEnd

        void * heapBegin;                                                                       // start of heap
        void * heapEnd;                                                                         // logical end of heap
        size_t heapRemaining;                                                           // amount of storage not allocated in the current chunk
        size_t pageSize;                                                                        // architecture pagesize
        size_t heapExpand;                                                                      // sbrk advance
        size_t mmapStart;                                                                       // cross over point for mmap
        unsigned int maxBucketsUsed;                                            // maximum number of buckets in use

        Heap * heapManagersList;                                                        // heap-list head
        Heap * freeHeapManagersList;                                            // free-list head

        // Heap superblocks are not linked; heaps in superblocks are linked via intrusive links.
        Heap * heapManagersStorage;                                                     // next heap to use in heap superblock
        Heap * heapManagersStorageEnd;                                          // logical heap outside of superblock's end

        #ifdef __STATISTICS__
        HeapStatistics stats;                                                           // global stats for thread-local heaps to add there counters when exiting
        unsigned long int threads_started, threads_exited;      // counts threads that have started and exited
        unsigned long int reused_heap, new_heap;                        // counts reusability of heaps
        unsigned int sbrk_calls;
        unsigned long long int sbrk_storage;
        int stats_fd;
        #endif // __STATISTICS__
}; // HeapMaster


#ifdef FASTLOOKUP
enum { LookupSizes = 65_536 + sizeof(Heap.Storage) };   // number of fast lookup sizes
static unsigned char lookup[LookupSizes];                               // O(1) lookup for small sizes
#endif // FASTLOOKUP

static volatile bool heapMasterBootFlag = false;                // trigger for first heap
static HeapMaster heapMaster @= {};                                             // program global

static void heapMasterCtor();
static void heapMasterDtor();
static Heap * getHeap();


// Size of array must harmonize with NoBucketSizes and individual bucket sizes must be multiple of 16.
// Smaller multiples of 16 and powers of 2 are common allocation sizes, so make them generate the minimum required bucket size.
// malloc(0) returns 0p, so no bucket is necessary for 0 bytes returning an address that can be freed.
static const unsigned int bucketSizes[] @= {                    // different bucket sizes
        16 + sizeof(Heap.Storage), 32 + sizeof(Heap.Storage), 48 + sizeof(Heap.Storage), 64 + sizeof(Heap.Storage), // 4
        96 + sizeof(Heap.Storage), 112 + sizeof(Heap.Storage), 128 + sizeof(Heap.Storage), // 3
        160, 192, 224, 256 + sizeof(Heap.Storage), // 4
        320, 384, 448, 512 + sizeof(Heap.Storage), // 4
        640, 768, 896, 1_024 + sizeof(Heap.Storage), // 4
        1_536, 2_048 + sizeof(Heap.Storage), // 2
        2_560, 3_072, 3_584, 4_096 + sizeof(Heap.Storage), // 4
        6_144, 8_192 + sizeof(Heap.Storage), // 2
        9_216, 10_240, 11_264, 12_288, 13_312, 14_336, 15_360, 16_384 + sizeof(Heap.Storage), // 8
        18_432, 20_480, 22_528, 24_576, 26_624, 28_672, 30_720, 32_768 + sizeof(Heap.Storage), // 8
        36_864, 40_960, 45_056, 49_152, 53_248, 57_344, 61_440, 65_536 + sizeof(Heap.Storage), // 8
        73_728, 81_920, 90_112, 98_304, 106_496, 114_688, 122_880, 131_072 + sizeof(Heap.Storage), // 8
        147_456, 163_840, 180_224, 196_608, 212_992, 229_376, 245_760, 262_144 + sizeof(Heap.Storage), // 8
        294_912, 327_680, 360_448, 393_216, 425_984, 458_752, 491_520, 524_288 + sizeof(Heap.Storage), // 8
        655_360, 786_432, 917_504, 1_048_576 + sizeof(Heap.Storage), // 4
        1_179_648, 1_310_720, 1_441_792, 1_572_864, 1_703_936, 1_835_008, 1_966_080, 2_097_152 + sizeof(Heap.Storage), // 8
        2_621_440, 3_145_728, 3_670_016, 4_194_304 + sizeof(Heap.Storage), // 4
};

static_assert( sizeof(bucketSizes) == NoBucketSizes * sizeof(unsigned int), "size of bucket array wrong" );


// extern visibility, used by runtime kernel
libcfa_public size_t __page_size;                                               // architecture pagesize
libcfa_public int __map_prot;                                                   // common mmap/mprotect protection


// Thread-local storage is allocated lazily when the storage is accessed.
static __thread size_t PAD1 CALIGN TLSMODEL __attribute__(( unused )); // protect false sharing
static __thread Heap * heapManager CALIGN TLSMODEL;
static __thread bool heapManagerBootFlag CALIGN TLSMODEL = false;
static __thread size_t PAD2 CALIGN TLSMODEL __attribute__(( unused )); // protect further false sharing


// declare helper functions for HeapMaster
void noMemory();                                                                                // forward, called by "builtin_new" when malloc returns 0


void heapMasterCtor() with( heapMaster ) {
        // Singleton pattern to initialize heap master

        verify( bucketSizes[0] == (16 + sizeof(Heap.Storage)) );

        __page_size = sysconf( _SC_PAGESIZE );
        __map_prot = PROT_READ | PROT_WRITE | PROT_EXEC;

        extLock = 0;
        mgrLock = 0;

        char * end = (char *)sbrk( 0 );
        heapBegin = heapEnd = sbrk( (char *)ceiling2( (long unsigned int)end, libAlign() ) - end ); // move start of heap to multiple of alignment
        heapRemaining = 0;
        heapExpand = malloc_expansion();
        mmapStart = malloc_mmap_start();

        // find the closest bucket size less than or equal to the mmapStart size
        maxBucketsUsed = Bsearchl( mmapStart, bucketSizes, NoBucketSizes ); // binary search

        verify( (mmapStart >= pageSize) && (bucketSizes[NoBucketSizes - 1] >= mmapStart) );
        verify( maxBucketsUsed < NoBucketSizes );                       // subscript failure ?
        verify( mmapStart <= bucketSizes[maxBucketsUsed] ); // search failure ?

        heapManagersList = 0p;
        freeHeapManagersList = 0p;

        heapManagersStorage = 0p;
        heapManagersStorageEnd = 0p;

        #ifdef __STATISTICS__
        HeapStatisticsCtor( stats );                                            // clear statistic counters
        threads_started = threads_exited = 0;
        reused_heap = new_heap = 0;
        sbrk_calls = sbrk_storage = 0;
        stats_fd = STDERR_FILENO;
        #endif // __STATISTICS__

        #ifdef FASTLOOKUP
        for ( unsigned int i = 0, idx = 0; i < LookupSizes; i += 1 ) {
                if ( i > bucketSizes[idx] ) idx += 1;
                lookup[i] = idx;
                verify( i <= bucketSizes[idx] );
                verify( (i <= 32 && idx == 0) || (i > bucketSizes[idx - 1]) );
        } // for
        #endif // FASTLOOKUP

        heapMasterBootFlag = true;
} // heapMasterCtor


#define NO_MEMORY_MSG "**** Error **** insufficient heap memory available to allocate %zd new bytes."

Heap * getHeap() with( heapMaster ) {
        Heap * heap;
        if ( freeHeapManagersList ) {                                           // free heap for reused ?
                heap = freeHeapManagersList;
                freeHeapManagersList = heap->nextFreeHeapManager;

                #ifdef __STATISTICS__
                reused_heap += 1;
                #endif // __STATISTICS__
        } else {                                                                                        // free heap not found, create new
                // Heap size is about 12K, FreeHeader (128 bytes because of cache alignment) * NoBucketSizes (91) => 128 heaps *
                // 12K ~= 120K byte superblock.  Where 128-heap superblock handles a medium sized multi-processor server.
                size_t remaining = heapManagersStorageEnd - heapManagersStorage; // remaining free heaps in superblock
                if ( ! heapManagersStorage || remaining == 0 ) {
                        // Each block of heaps is a multiple of the number of cores on the computer.
                        int HeapDim = get_nprocs();                                     // get_nprocs_conf does not work
                        size_t size = HeapDim * sizeof( Heap );

                        heapManagersStorage = (Heap *)mmap( 0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 );
                        if ( unlikely( heapManagersStorage == (Heap *)MAP_FAILED ) ) { // failed ?
                                if ( errno == ENOMEM ) abort( NO_MEMORY_MSG, size ); // no memory
                                // Do not call strerror( errno ) as it may call malloc.
                                abort( "**** Error **** attempt to allocate block of heaps of size %zu bytes and mmap failed with errno %d.", size, errno );
                        } // if
                        heapManagersStorageEnd = &heapManagersStorage[HeapDim]; // outside array
                } // if

                heap = heapManagersStorage;
                heapManagersStorage = heapManagersStorage + 1; // bump next heap

                #if defined( __STATISTICS__ ) || defined( __CFA_DEBUG__ )
                heap->nextHeapManager = heapManagersList;
                #endif // __STATISTICS__ || __CFA_DEBUG__
                heapManagersList = heap;

                #ifdef __STATISTICS__
                new_heap += 1;
                #endif // __STATISTICS__

                with( *heap ) {
                        for ( unsigned int j = 0; j < NoBucketSizes; j += 1 ) { // initialize free lists
                                #ifdef OWNERSHIP
                                #ifdef RETURNSPIN
                                freeLists[j].returnLock = 0;
                                freeLists[j].returnList = 0p;
                                #endif // RETURNSPIN
                                #endif // OWNERSHIP

                                freeLists[j].freeList = 0p;
                                freeLists[j].homeManager = heap;
                                freeLists[j].blockSize = bucketSizes[j];
                        } // for

                        heapBuffer = 0p;
                        heapReserve = 0;
                        nextFreeHeapManager = 0p;
                        #ifdef __CFA_DEBUG__
                        allocUnfreed = 0;
                        #endif // __CFA_DEBUG__
                        heapManagerBootFlag = true;
                } // with
        } // if

        return heap;
} // getHeap


void heapManagerCtor() libcfa_public {
        if ( unlikely( ! heapMasterBootFlag ) ) heapMasterCtor();

        lock( heapMaster.mgrLock );                                                     // protect heapMaster counters

        assert( ! heapManagerBootFlag );

        // get storage for heap manager

        heapManager = getHeap();

        #ifdef __STATISTICS__
        HeapStatisticsCtor( heapManager->stats );                       // heap local
        heapMaster.threads_started += 1;
        #endif // __STATISTICS__

        unlock( heapMaster.mgrLock );
} // heapManagerCtor


void heapManagerDtor() libcfa_public {
  if ( unlikely( ! heapManagerBootFlag ) ) return;              // thread never used ?

        lock( heapMaster.mgrLock );

        // place heap on list of free heaps for reusability
        heapManager->nextFreeHeapManager = heapMaster.freeHeapManagersList;
        heapMaster.freeHeapManagersList = heapManager;

        #ifdef __STATISTICS__
        heapMaster.stats += heapManager->stats;                         // retain this heap's statistics
        heapMaster.threads_exited += 1;
        #endif // __STATISTICS__

        // Do not set heapManager to NULL because it is used after Cforall is shutdown but before the program shuts down.

        heapManagerBootFlag = false;
        unlock( heapMaster.mgrLock );
} // heapManagerDtor


//####################### Memory Allocation Routines Helpers ####################


extern int cfa_main_returned;                                                   // from interpose.cfa
extern "C" {
        void memory_startup( void ) {                                           // singleton => called once at start of program
                if ( ! heapMasterBootFlag ) heapManagerCtor();  // sanity check
        } // memory_startup

        void memory_shutdown( void ) {
                heapManagerDtor();
        } // memory_shutdown

        void heapAppStart() {                                                           // called by __cfaabi_appready_startup
                verify( heapManager );
                #ifdef __CFA_DEBUG__
                heapManager->allocUnfreed = 0;                                  // clear prior allocation counts
                #endif // __CFA_DEBUG__

                #ifdef __STATISTICS__
                HeapStatisticsCtor( heapManager->stats );               // clear prior statistic counters
                #endif // __STATISTICS__
        } // heapAppStart

        void heapAppStop() {                                                            // called by __cfaabi_appready_startdown
                fclose( stdin ); fclose( stdout );                              // free buffer storage
          if ( ! cfa_main_returned ) return;                            // do not check unfreed storage if exit called

                #ifdef __STATISTICS__
                if ( getenv( "CFA_MALLOC_STATS" ) ) {                   // check for external printing
                        malloc_stats();
                } // if
                #endif // __STATISTICS__

                #ifdef __CFA_DEBUG__
                // allocUnfreed is set to 0 when a heap is created and it accumulates any unfreed storage during its multiple thread
                // usages.  At the end, add up each heap allocUnfreed value across all heaps to get the total unfreed storage.
                ptrdiff_t allocUnfreed = 0;
                for ( Heap * heap = heapMaster.heapManagersList; heap; heap = heap->nextHeapManager ) {
                        allocUnfreed += heap->allocUnfreed;
                } // for

                allocUnfreed -= malloc_unfreed();                               // subtract any user specified unfreed storage
                if ( allocUnfreed > 0 ) {
                        // DO NOT USE STREAMS AS THEY MAY BE UNAVAILABLE AT THIS POINT.
                        char helpText[512];
                        __cfaabi_bits_print_buffer( STDERR_FILENO, helpText, sizeof(helpText),
                                                                                "CFA warning (UNIX pid:%ld) : program terminating with %td(%#tx) bytes of storage allocated but not freed.\n"
                                                                                "Possible cause is mismatched allocation/deallocation calls (malloc/free), direct constructor call without a direct destructor call, or system/library routines not freeing storage.\n",
                                                                                (long int)getpid(), allocUnfreed, allocUnfreed ); // always print the UNIX pid
                } // if
                #endif // __CFA_DEBUG__
        } // heapAppStop
} // extern "C"


#ifdef __STATISTICS__
#define prtFmt \
        "\nHeap statistics: (storage request / allocation)\n" \
        "  malloc    >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  aalloc    >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  calloc    >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  memalign  >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  amemalign >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  cmemalign >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  resize    >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  realloc   >0 calls %'u; 0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  free      !null calls %'u; null/0 calls %'u; storage %'llu / %'llu bytes\n" \
        "  return    pulls %'u; pushes %'u; storage %'llu / %'llu bytes\n" \
        "  sbrk      calls %'u; storage %'llu bytes\n" \
        "  mmap      calls %'u; storage %'llu / %'llu bytes\n" \
        "  munmap    calls %'u; storage %'llu / %'llu bytes\n" \
        "  threads   started %'lu; exited %'lu\n" \
        "  heaps     new %'lu; reused %'lu\n"

// Use "write" because streams may be shutdown when calls are made.
static int printStats( HeapStatistics & stats ) with( heapMaster, stats ) {     // see malloc_stats
        char helpText[sizeof(prtFmt) + 1024];                           // space for message and values
        return __cfaabi_bits_print_buffer( stats_fd, helpText, sizeof(helpText), prtFmt,
                        malloc_calls, malloc_0_calls, malloc_storage_request, malloc_storage_alloc,
                        aalloc_calls, aalloc_0_calls, aalloc_storage_request, aalloc_storage_alloc,
                        calloc_calls, calloc_0_calls, calloc_storage_request, calloc_storage_alloc,
                        memalign_calls, memalign_0_calls, memalign_storage_request, memalign_storage_alloc,
                        amemalign_calls, amemalign_0_calls, amemalign_storage_request, amemalign_storage_alloc,
                        cmemalign_calls, cmemalign_0_calls, cmemalign_storage_request, cmemalign_storage_alloc,
                        resize_calls, resize_0_calls, resize_storage_request, resize_storage_alloc,
                        realloc_calls, realloc_0_calls, realloc_storage_request, realloc_storage_alloc,
                        free_calls, free_null_0_calls, free_storage_request, free_storage_alloc,
                        return_pulls, return_pushes, return_storage_request, return_storage_alloc,
                        sbrk_calls, sbrk_storage,
                        mmap_calls, mmap_storage_request, mmap_storage_alloc,
                        munmap_calls, munmap_storage_request, munmap_storage_alloc,
                        threads_started, threads_exited,
                        new_heap, reused_heap
                );
} // printStats

#define prtFmtXML \
        "<malloc version=\"1\">\n" \
        "<heap nr=\"0\">\n" \
        "<sizes>\n" \
        "</sizes>\n" \
        "<total type=\"malloc\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"aalloc\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"calloc\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"memalign\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"amemalign\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"cmemalign\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"resize\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"realloc\" >0 count=\"%'u;\" 0 count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"free\" !null=\"%'u;\" 0 null/0=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"return\" pulls=\"%'u;\" 0 pushes=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"sbrk\" count=\"%'u;\" size=\"%'llu\"/> bytes\n" \
        "<total type=\"mmap\" count=\"%'u;\" size=\"%'llu / %'llu\" / > bytes\n" \
        "<total type=\"munmap\" count=\"%'u;\" size=\"%'llu / %'llu\"/> bytes\n" \
        "<total type=\"threads\" started=\"%'lu;\" exited=\"%'lu\"/>\n" \
        "<total type=\"heaps\" new=\"%'lu;\" reused=\"%'lu\"/>\n" \
        "</malloc>"

static int printStatsXML( HeapStatistics & stats, FILE * stream ) with( heapMaster, stats ) { // see malloc_info
        char helpText[sizeof(prtFmtXML) + 1024];                        // space for message and values
        return __cfaabi_bits_print_buffer( fileno( stream ), helpText, sizeof(helpText), prtFmtXML,
                        malloc_calls, malloc_0_calls, malloc_storage_request, malloc_storage_alloc,
                        aalloc_calls, aalloc_0_calls, aalloc_storage_request, aalloc_storage_alloc,
                        calloc_calls, calloc_0_calls, calloc_storage_request, calloc_storage_alloc,
                        memalign_calls, memalign_0_calls, memalign_storage_request, memalign_storage_alloc,
                        amemalign_calls, amemalign_0_calls, amemalign_storage_request, amemalign_storage_alloc,
                        cmemalign_calls, cmemalign_0_calls, cmemalign_storage_request, cmemalign_storage_alloc,
                        resize_calls, resize_0_calls, resize_storage_request, resize_storage_alloc,
                        realloc_calls, realloc_0_calls, realloc_storage_request, realloc_storage_alloc,
                        free_calls, free_null_0_calls, free_storage_request, free_storage_alloc,
                        return_pulls, return_pushes, return_storage_request, return_storage_alloc,
                        sbrk_calls, sbrk_storage,
                        mmap_calls, mmap_storage_request, mmap_storage_alloc,
                    munmap_calls, munmap_storage_request, munmap_storage_alloc,
                        threads_started, threads_exited,
                        new_heap, reused_heap
                );
} // printStatsXML

static HeapStatistics & collectStats( HeapStatistics & stats ) with( heapMaster ) {
        lock( heapMaster.mgrLock );

        stats += heapMaster.stats;
        for ( Heap * heap = heapManagersList; heap; heap = heap->nextHeapManager ) {
                stats += heap->stats;
        } // for

        unlock( heapMaster.mgrLock );
        return stats;
} // collectStats

static inline void clearStats() {
        lock( heapMaster.mgrLock );

        // Zero the heap master and all active thread heaps.
        HeapStatisticsCtor( heapMaster.stats );
        for ( Heap * heap = heapMaster.heapManagersList; heap; heap = heap->nextHeapManager ) {
                HeapStatisticsCtor( heap->stats );
        } // for

        unlock( heapMaster.mgrLock );
} // clearStats
#endif // __STATISTICS__


static bool setMmapStart( size_t value ) with( heapMaster ) { // true => mmapped, false => sbrk
  if ( value < __page_size || bucketSizes[NoBucketSizes - 1] < value ) return false;
        mmapStart = value;                                                                      // set global

        // find the closest bucket size less than or equal to the mmapStart size
        maxBucketsUsed = Bsearchl( mmapStart, bucketSizes, NoBucketSizes ); // binary search

        verify( maxBucketsUsed < NoBucketSizes );                       // subscript failure ?
        verify( mmapStart <= bucketSizes[maxBucketsUsed] ); // search failure ?
        return true;
} // setMmapStart


// <-------+----------------------------------------------------> bsize (bucket size)
// |header |addr
//==================================================================================
//                   align/offset |
// <-----------------<------------+-----------------------------> bsize (bucket size)
//                   |fake-header | addr
#define HeaderAddr( addr ) ((Heap.Storage.Header *)( (char *)addr - sizeof(Heap.Storage) ))
#define RealHeader( header ) ((Heap.Storage.Header *)((char *)header - header->kind.fake.offset))

// <-------<<--------------------- dsize ---------------------->> bsize (bucket size)
// |header |addr
//==================================================================================
//                   align/offset |
// <------------------------------<<---------- dsize --------->>> bsize (bucket size)
//                   |fake-header |addr
#define DataStorage( bsize, addr, header ) (bsize - ( (char *)addr - (char *)header ))


inline __attribute__((always_inline))
static void checkAlign( size_t alignment ) {
        if ( unlikely( alignment < libAlign() || ! is_pow2( alignment ) ) ) {
                abort( "**** Error **** alignment %zu for memory allocation is less than %d and/or not a power of 2.", alignment, libAlign() );
        } // if
} // checkAlign


inline __attribute__((always_inline))
static void checkHeader( bool check, const char name[], void * addr ) {
        if ( unlikely( check ) ) {                                                      // bad address ?
                abort( "**** Error **** attempt to %s storage %p with address outside the heap.\n"
                           "Possible cause is duplicate free on same block or overwriting of memory.",
                           name, addr );
        } // if
} // checkHeader


// Manipulate sticky bits stored in unused 3 low-order bits of an address.
//   bit0 => alignment => fake header
//   bit1 => zero filled (calloc)
//   bit2 => mapped allocation versus sbrk
#define StickyBits( header ) (((header)->kind.real.blockSize & 0x7))
#define ClearStickyBits( addr ) (typeof(addr))((uintptr_t)(addr) & ~7)
#define MarkAlignmentBit( align ) ((align) | 1)
#define AlignmentBit( header ) ((((header)->kind.fake.alignment) & 1))
#define ClearAlignmentBit( header ) (((header)->kind.fake.alignment) & ~1)
#define ZeroFillBit( header ) ((((header)->kind.real.blockSize) & 2))
#define ClearZeroFillBit( header ) ((((header)->kind.real.blockSize) &= ~2))
#define MarkZeroFilledBit( header ) ((header)->kind.real.blockSize |= 2)
#define MmappedBit( header ) ((((header)->kind.real.blockSize) & 4))
#define MarkMmappedBit( size ) ((size) | 4)


inline __attribute__((always_inline))
static void fakeHeader( Heap.Storage.Header *& header, size_t & alignment ) {
        if ( unlikely( AlignmentBit( header ) ) ) {                     // fake header ?
                alignment = ClearAlignmentBit( header );                // clear flag from value
                #ifdef __CFA_DEBUG__
                checkAlign( alignment );                                                // check alignment
                #endif // __CFA_DEBUG__
                header = RealHeader( header );                                  // backup from fake to real header
        } else {
                alignment = libAlign();                                                 // => no fake header
        } // if
} // fakeHeader


inline __attribute__((always_inline))
static bool headers( const char name[] __attribute__(( unused )), void * addr, Heap.Storage.Header *& header,
                                                        Heap.FreeHeader *& freeHead, size_t & size, size_t & alignment ) with( heapMaster, *heapManager ) {
        header = HeaderAddr( addr );

        #ifdef __CFA_DEBUG__
        checkHeader( header < (Heap.Storage.Header *)heapBegin, name, addr ); // bad low address ?
        #endif // __CFA_DEBUG__

        if ( likely( ! StickyBits( header ) ) ) {                       // no sticky bits ?
                freeHead = (Heap.FreeHeader *)(header->kind.real.home);
                alignment = libAlign();
        } else {
                fakeHeader( header, alignment );
                if ( unlikely( MmappedBit( header ) ) ) {               // mmapped storage ?
                        verify( addr < heapBegin || heapEnd < addr );
                        size = ClearStickyBits( header->kind.real.blockSize ); // mmap size
                        freeHead = 0p;                                                          // prevent uninitialized warning
                        return true;
                } // if

                freeHead = (Heap.FreeHeader *)(ClearStickyBits( header->kind.real.home ));
        } // if
        size = freeHead->blockSize;

        #ifdef __CFA_DEBUG__
        checkHeader( header < (Heap.Storage.Header *)heapBegin || (Heap.Storage.Header *)heapEnd < header, name, addr ); // bad address ? (offset could be + or -)

        Heap * homeManager;
        if ( unlikely( freeHead == 0p || // freed and only free-list node => null link
                                   // freed and link points at another free block not to a bucket in the bucket array.
                                   (homeManager = freeHead->homeManager, freeHead < &homeManager->freeLists[0] ||
                                        &homeManager->freeLists[NoBucketSizes] <= freeHead ) ) ) {
                abort( "**** Error **** attempt to %s storage %p with corrupted header.\n"
                           "Possible cause is duplicate free on same block or overwriting of header information.",
                           name, addr );
        } // if
        #endif // __CFA_DEBUG__

        return false;
} // headers


static void * master_extend( size_t size ) with( heapMaster ) {
        lock( extLock );

        ptrdiff_t rem = heapRemaining - size;
        if ( unlikely( rem < 0 ) ) {                                            // negative ?
                // If the size requested is bigger than the current remaining storage, increase the size of the heap.

                size_t increase = ceiling2( size > heapExpand ? size : heapExpand, libAlign() );
                if ( unlikely( sbrk( increase ) == (void *)-1 ) ) {     // failed, no memory ?
                        unlock( extLock );
                        abort( NO_MEMORY_MSG, size );                           // give up
                } // if

                // Make storage executable for thunks.
                if ( mprotect( (char *)heapEnd + heapRemaining, increase, __map_prot ) ) {
                        unlock( extLock );
                        abort( "**** Error **** attempt to make heap storage executable for thunks and mprotect failed with errno %d.", errno );
                } // if

                rem = heapRemaining + increase - size;

                #ifdef __STATISTICS__
                sbrk_calls += 1;
                sbrk_storage += increase;
                #endif // __STATISTICS__
        } // if

        Heap.Storage * block = (Heap.Storage *)heapEnd;
        heapRemaining = rem;
        heapEnd = (char *)heapEnd + size;

        unlock( extLock );
        return block;
} // master_extend


__attribute__(( noinline ))
static void * manager_extend( size_t size ) with( *heapManager ) {
        ptrdiff_t rem = heapReserve - size;

        if ( unlikely( rem < 0 ) ) {                                            // negative ?
                // If the size requested is bigger than the current remaining reserve, use the current reserve to populate
                // smaller freeLists, and increase the reserve.

                rem = heapReserve;                                                              // positive

                if ( (unsigned int)rem >= bucketSizes[0] ) {    // minimal size ? otherwise ignore
                        size_t bucket;
                        #ifdef FASTLOOKUP
                        if ( likely( rem < LookupSizes ) ) bucket = lookup[rem];
                        #endif // FASTLOOKUP
                                bucket = Bsearchl( rem, bucketSizes, heapMaster.maxBucketsUsed );
                        verify( 0 <= bucket && bucket <= heapMaster.maxBucketsUsed );
                        Heap.FreeHeader * freeHead = &(freeLists[bucket]);

                        // The remaining storage may not be bucket size, whereas all other allocations are. Round down to previous
                        // bucket size in this case.
                        if ( unlikely( freeHead->blockSize > (size_t)rem ) ) freeHead -= 1;
                        Heap.Storage * block = (Heap.Storage *)heapBuffer;

                        block->header.kind.real.next = freeHead->freeList; // push on stack
                        freeHead->freeList = block;
                } // if

                size_t increase = ceiling( size > ( heapMaster.heapExpand / 10 ) ? size : ( heapMaster.heapExpand / 10 ), libAlign() );
                heapBuffer = master_extend( increase );
                rem = increase - size;
        } // if

        Heap.Storage * block = (Heap.Storage *)heapBuffer;
        heapReserve = rem;
        heapBuffer = (char *)heapBuffer + size;

        return block;
} // manager_extend


#ifdef __STATISTICS__
#define STAT_NAME __counter
#define STAT_PARM , unsigned int STAT_NAME
#define STAT_ARG( name ) , name
#define STAT_0_CNT( counter ) heapManager->stats.counters[counter].calls_0 += 1
#else
#define STAT_NAME
#define STAT_PARM
#define STAT_ARG( name )
#define STAT_0_CNT( counter )
#endif // __STATISTICS__

#define BOOT_HEAP_MANAGER \
        if ( unlikely( ! heapMasterBootFlag ) ) { \
                heapManagerCtor(); /* trigger for first heap */ \
        } /* if */ \
        verify( heapManager );

#define __NONNULL_0_ALLOC__ /* Uncomment to return non-null address for malloc( 0 ). */
#ifndef __NONNULL_0_ALLOC__
#define __NULL_0_ALLOC__( counter, ... ) /* 0 byte allocation returns null pointer */ \
        if ( unlikely( size == 0 ) ) { \
                STAT_0_CNT( counter ); \
                __VA_ARGS__; /* call routine, if specified */ \
                return 0p; \
        } /* if */
#else
#define __NULL_0_ALLOC__( counter, ... )
#endif // __NONNULL_0_ALLOC__

#ifdef __DEBUG__
#define __OVERFLOW_MALLOC__( ... ) \
        if ( unlikely( size > ULONG_MAX - sizeof(Heap.Storage) ) ) { /* error check */ \
                __VA_ARGS__; /* call routine, if specified */ \
                return 0p; \
        } /* if */
#else
#define __OVERFLOW_MALLOC__( ... )
#endif // __DEBUG__

#define PROLOG( counter, ... ) \
        BOOT_HEAP_MANAGER; \
        __NULL_0_ALLOC__( counter, __VA_ARGS__ ) \
        __OVERFLOW_MALLOC__( __VA_ARGS__ )

#define SCRUB_SIZE 1024lu
// Do not use '\xfe' for scrubbing because dereferencing an address composed of it causes a SIGSEGV *without* a valid IP
// pointer in the interrupt frame.
#define SCRUB '\xff'

static void * doMalloc( size_t size STAT_PARM ) libcfa_nopreempt with( *heapManager ) {
        PROLOG( STAT_NAME );

        Heap.Storage * block;                                                           // pointer to new block of storage

        // Look up size in the size list.  Make sure the user request includes space for the header that must be allocated
        // along with the block and is a multiple of the alignment size.
        size_t tsize = size + sizeof(Heap.Storage);

        #ifdef __STATISTICS__
        #ifdef __NONNULL_0_ALLOC__
        if ( unlikely( size == 0 ) )                                            // malloc( 0 ) ?
                stats.counters[STAT_NAME].calls_0 += 1;
        else
        #endif // __NONNULL_0_ALLOC__
                stats.counters[STAT_NAME].calls += 1;
        stats.counters[STAT_NAME].request += size;
        #endif // __STATISTICS__

        #ifdef __CFA_DEBUG__
        allocUnfreed += size;
        #endif // __CFA_DEBUG__

        if ( likely( tsize < heapMaster.mmapStart ) ) {         // small size => sbrk
                size_t bucket;
                #ifdef FASTLOOKUP
                if ( likely( tsize < LookupSizes ) ) bucket = lookup[tsize];
                else
                #endif // FASTLOOKUP
                        bucket = Bsearchl( tsize, bucketSizes, heapMaster.maxBucketsUsed );
                verify( 0 <= bucket && bucket <= heapMaster.maxBucketsUsed );
                Heap.FreeHeader * freeHead = &freeLists[bucket];

                verify( freeHead <= &freeLists[heapMaster.maxBucketsUsed] ); // subscripting error ?
                verify( tsize <= freeHead->blockSize );                 // search failure ?

                tsize = freeHead->blockSize;                                    // total space needed for request
                #ifdef __STATISTICS__
                stats.counters[STAT_NAME].alloc += tsize;
                #endif // __STATISTICS__

                block = freeHead->freeList;                                             // remove node from stack
                if ( unlikely( block == 0p ) ) {                                // no free block ?
                        // Freelist for this size is empty, so check return list (OWNERSHIP), or carve it out of the heap if there
                        // is enough left, or get some more heap storage and carve it off.
                        #ifdef OWNERSHIP
                        if ( unlikely( freeHead->returnList ) ) {       // race, get next time if lose race
                                #ifdef RETURNSPIN
                                lock( freeHead->returnLock );
                                block = freeHead->returnList;
                                freeHead->returnList = 0p;
                                unlock( freeHead->returnLock );
                                #else
                                block = __atomic_exchange_n( &freeHead->returnList, 0p, __ATOMIC_SEQ_CST );
                                #endif // RETURNSPIN

                                verify( block );
                                #ifdef __STATISTICS__
                                stats.return_pulls += 1;
                                #endif // __STATISTICS__

                                // OK TO BE PREEMPTED HERE AS heapManager IS NO LONGER ACCESSED.

                                freeHead->freeList = block->header.kind.real.next; // merge returnList into freeHead
                        } else {
                        #endif // OWNERSHIP
                                // Do not leave kernel thread as manager_extend accesses heapManager.
                                disable_interrupts();
                                block = (Heap.Storage *)manager_extend( tsize ); // mutual exclusion on call
                                enable_interrupts( false );

                                // OK TO BE PREEMPTED HERE AS heapManager IS NO LONGER ACCESSED.

                                #ifdef __CFA_DEBUG__
                                // Scrub new memory so subsequent uninitialized usages might fail. Only scrub the first SCRUB_SIZE bytes.
                                memset( block->data, SCRUB, min( SCRUB_SIZE, tsize - sizeof(Heap.Storage) ) );
                                #endif // __CFA_DEBUG__
                        #ifdef OWNERSHIP
                        } // if
                        #endif // OWNERSHIP
                } else {
                        // Memory is scrubbed in doFree.
                        freeHead->freeList = block->header.kind.real.next;
                } // if

                block->header.kind.real.home = freeHead;                // pointer back to free list of apropriate size
        } else {                                                                                        // large size => mmap
  if ( unlikely( size > ULONG_MAX - __page_size ) ) return 0p;
                tsize = ceiling2( tsize, __page_size );                 // must be multiple of page size

                #ifdef __STATISTICS__
                stats.counters[STAT_NAME].alloc += tsize;
                stats.mmap_calls += 1;
                stats.mmap_storage_request += size;
                stats.mmap_storage_alloc += tsize;
                #endif // __STATISTICS__

                disable_interrupts();
                block = (Heap.Storage *)mmap( 0, tsize, __map_prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 );
                enable_interrupts( false );

                // OK TO BE PREEMPTED HERE AS heapManager IS NO LONGER ACCESSED.

                if ( unlikely( block == (Heap.Storage *)MAP_FAILED ) ) { // failed ?
                        if ( errno == ENOMEM ) abort( NO_MEMORY_MSG, tsize ); // no memory
                        // Do not call strerror( errno ) as it may call malloc.
                        abort( "**** Error **** attempt to allocate large object (> %zu) of size %zu bytes and mmap failed with errno %d.",
                                   size, heapMaster.mmapStart, errno );
                } // if
                block->header.kind.real.blockSize = MarkMmappedBit( tsize ); // storage size for munmap

                #ifdef __CFA_DEBUG__
                // Scrub new memory so subsequent uninitialized usages might fail. Only scrub the first SCRUB_SIZE bytes. The
                // rest of the storage set to 0 by mmap.
                memset( block->data, SCRUB, min( SCRUB_SIZE, tsize - sizeof(Heap.Storage) ) );
                #endif // __CFA_DEBUG__
        } // if

        block->header.kind.real.size = size;                            // store allocation size
        void * addr = &(block->data);                                           // adjust off header to user bytes
        verify( ((uintptr_t)addr & (libAlign() - 1)) == 0 ); // minimum alignment ?

        #ifdef __CFA_DEBUG__
        if ( traceHeap() ) {
                char helpText[64];
                __cfaabi_bits_print_buffer( STDERR_FILENO, helpText, sizeof(helpText),
                                                                        "%p = Malloc( %zu ) (allocated %zu)\n", addr, size, tsize ); // print debug/nodebug
        } // if
        #endif // __CFA_DEBUG__

//      poll_interrupts();                                                                      // call rollforward

        return addr;
} // doMalloc


static void doFree( void * addr ) libcfa_nopreempt with( *heapManager ) {
        // char buf[64];
        // int len = sprintf( buf, "doFree addr %p\n", addr );
        // write( 2, buf, len );

        verify( addr );

        // detect free after thread-local storage destruction and use global stats in that case

        Heap.Storage.Header * header;
        Heap.FreeHeader * freeHead;
        size_t size, alignment;

        bool mapped = headers( "free", addr, header, freeHead, size, alignment );
        #if defined( __STATISTICS__ ) || defined( __CFA_DEBUG__ )
        size_t rsize = header->kind.real.size;                          // optimization
        #endif // __STATISTICS__ || __CFA_DEBUG__

        // Do not move these down because heap can be null!
        #ifdef __STATISTICS__
        #ifdef __NONNULL_0_ALLOC__
        if ( unlikely( rsize == 0 ) )                                           // malloc( 0 ) ?
                stats.free_null_0_calls += 1;
        else
        #endif // __NONNULL_0_ALLOC__
                heapManager->stats.free_calls += 1;                             // count free amd implicit frees from resize/realloc
        stats.free_storage_request += rsize;
        stats.free_storage_alloc += size;
        #endif // __STATISTICS__

        #ifdef __CFA_DEBUG__
        allocUnfreed -= rsize;
        #endif // __CFA_DEBUG__

        if ( unlikely( mapped ) ) {                                                     // mmapped ?
                #ifdef __STATISTICS__
                stats.munmap_calls += 1;
                stats.munmap_storage_request += rsize;
                stats.munmap_storage_alloc += size;
                #endif // __STATISTICS__

                // OK TO BE PREEMPTED HERE AS heapManager IS NO LONGER ACCESSED.

                // Does not matter where this storage is freed.
                if ( unlikely( munmap( header, size ) == -1 ) ) {
                        // Do not call strerror( errno ) as it may call malloc.
                        abort( "**** Error **** attempt to deallocate large object %p and munmap failed with errno %d.\n"
                                   "Possible cause is invalid delete pointer: either not allocated or with corrupt header.",
                                   addr, errno );
                } // if
        } else {
                assert( freeHead );
                #ifdef __CFA_DEBUG__
                // memset is NOT always inlined!
                disable_interrupts();
                // Scrub old memory so subsequent usages might fail. Only scrub the first/last SCRUB_SIZE bytes.
                char * data = ((Heap.Storage *)header)->data;   // data address
                size_t dsize = size - sizeof(Heap.Storage);             // data size
                if ( dsize <= SCRUB_SIZE * 2 ) {
                        memset( data, SCRUB, dsize );                           // scrub all
                } else {
                        memset( data, SCRUB, SCRUB_SIZE );                      // scrub front
                        memset( data + dsize - SCRUB_SIZE, SCRUB, SCRUB_SIZE ); // scrub back
                } // if
                enable_interrupts( false );
                #endif // __CFA_DEBUG__

                #ifdef OWNERSHIP
                if ( likely( heapManager == freeHead->homeManager ) ) { // belongs to this thread
                        header->kind.real.next = freeHead->freeList; // push on stack
                        freeHead->freeList = (Heap.Storage *)header;
                } else {                                                                                // return to thread owner
                        verify( heapManager );

                        #ifdef RETURNSPIN
                        lock( freeHead->returnLock );
                        header->kind.real.next = freeHead->returnList; // push to bucket return list
                        freeHead->returnList = (Heap.Storage *)header;
                        unlock( freeHead->returnLock );
                        #else                                                                           // lock free
                        header->kind.real.next = freeHead->returnList; // link new node to top node
                        // CAS resets header->kind.real.next = freeHead->returnList on failure
                        while ( ! __atomic_compare_exchange_n( &freeHead->returnList, &header->kind.real.next, (Heap.Storage *)header,
                                                                                                   false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST ) );

                        #ifdef __STATISTICS__
                        stats.return_pushes += 1;
                        stats.return_storage_request += rsize;
                        stats.return_storage_alloc += size;
                        #endif // __STATISTICS__
                        #endif // RETURNSPIN
                } // if

                #else                                                                                   // no OWNERSHIP

                // kind.real.home is address in owner thread's freeLists, so compute the equivalent position in this thread's freeList.
                freeHead = &freeLists[ClearStickyBits( (Heap.FreeHeader *)(header->kind.real.home) ) - &freeHead->homeManager->freeLists[0]];
                header->kind.real.next = freeHead->freeList;    // push on stack
                freeHead->freeList = (Heap.Storage *)header;
                #endif // ! OWNERSHIP

                // OK TO BE PREEMPTED HERE AS heapManager IS NO LONGER ACCESSED.
        } // if

        #ifdef __CFA_DEBUG__
        if ( traceHeap() ) {
                char helpText[64];
                __cfaabi_bits_print_buffer( STDERR_FILENO, helpText, sizeof(helpText),
                                                                        "Free( %p ) size:%zu\n", addr, size ); // print debug/nodebug
        } // if
        #endif // __CFA_DEBUG__

//      poll_interrupts();                                                                      // call rollforward
} // doFree


size_t prtFree( Heap & manager ) with( manager ) {
        size_t total = 0;
        #ifdef __STATISTICS__
        __cfaabi_bits_acquire();
        __cfaabi_bits_print_nolock( STDERR_FILENO, "\nBin lists (bin size : free blocks on list)\n" );
        #endif // __STATISTICS__
        for ( unsigned int i = 0; i < heapMaster.maxBucketsUsed; i += 1 ) {
                size_t size = freeLists[i].blockSize;
                #ifdef __STATISTICS__
                unsigned int N = 0;
                #endif // __STATISTICS__

                for ( Heap.Storage * p = freeLists[i].freeList; p != 0p; p = p->header.kind.real.next ) {
                        total += size;
                        #ifdef __STATISTICS__
                        N += 1;
                        #endif // __STATISTICS__
                } // for

                #ifdef __STATISTICS__
                __cfaabi_bits_print_nolock( STDERR_FILENO, "%7zu, %-7u  ", size, N );
                if ( (i + 1) % 8 == 0 ) __cfaabi_bits_print_nolock( STDERR_FILENO, "\n" );
                #endif // __STATISTICS__
        } // for
        #ifdef __STATISTICS__
        __cfaabi_bits_print_nolock( STDERR_FILENO, "\ntotal free blocks:%zu\n", total );
        __cfaabi_bits_release();
        #endif // __STATISTICS__
        return (char *)heapMaster.heapEnd - (char *)heapMaster.heapBegin - total;
} // prtFree


#ifdef __STATISTICS__
static void incCalls( size_t statName ) libcfa_nopreempt {
        heapManager->stats.counters[statName].calls += 1;
} // incCalls

static void incZeroCalls( size_t statName ) libcfa_nopreempt {
        heapManager->stats.counters[statName].calls_0 += 1;
} // incZeroCalls
#endif // __STATISTICS__

#ifdef __CFA_DEBUG__
static void incUnfreed( intptr_t offset ) libcfa_nopreempt {
        heapManager->allocUnfreed += offset;
} // incUnfreed
#endif // __CFA_DEBUG__


static void * memalignNoStats( size_t alignment, size_t size STAT_PARM ) {
        checkAlign( alignment );                                                        // check alignment

        // if alignment <= default alignment or size == 0, do normal malloc as two headers are unnecessary
  if ( unlikely( alignment <= libAlign() || size == 0 ) ) return doMalloc( size STAT_ARG( STAT_NAME ) );

        // Allocate enough storage to guarantee an address on the alignment boundary, and sufficient space before it for
        // administrative storage. NOTE, WHILE THERE ARE 2 HEADERS, THE FIRST ONE IS IMPLICITLY CREATED BY DOMALLOC.
        //      .-------------v-----------------v----------------v----------,
        //      | Real Header | ... padding ... |   Fake Header  | data ... |
        //      `-------------^-----------------^-+--------------^----------'
        //      |<--------------------------------' offset/align |<-- alignment boundary

        // subtract libAlign() because it is already the minimum alignment
        // add sizeof(Storage) for fake header
        size_t offset = alignment - libAlign() + sizeof(Heap.Storage);
        char * addr = (char *)doMalloc( size + offset STAT_ARG( STAT_NAME ) );

        // address in the block of the "next" alignment address
        char * user = (char *)ceiling2( (uintptr_t)(addr + sizeof(Heap.Storage)), alignment );

        // address of header from malloc
        Heap.Storage.Header * realHeader = HeaderAddr( addr );
        realHeader->kind.real.size = size;                                      // correct size to eliminate above alignment offset
        #ifdef __CFA_DEBUG__
        incUnfreed( -offset );                                                          // adjustment off the offset from call to doMalloc
        #endif // __CFA_DEBUG__

        // address of fake header *before* the alignment location
        Heap.Storage.Header * fakeHeader = HeaderAddr( user );

        // SKULLDUGGERY: insert the offset to the start of the actual storage block and remember alignment
        fakeHeader->kind.fake.offset = (char *)fakeHeader - (char *)realHeader;
        // SKULLDUGGERY: odd alignment implies fake header
        fakeHeader->kind.fake.alignment = MarkAlignmentBit( alignment );

        return user;
} // memalignNoStats


//####################### Memory Allocation Routines ####################


extern "C" {
        // Allocates size bytes and returns a pointer to the allocated memory.  The contents are undefined. If size is 0,
        // then malloc() returns a unique pointer value that can later be successfully passed to free().
        void * malloc( size_t size ) libcfa_public {
                return doMalloc( size STAT_ARG( MALLOC ) );
        } // malloc


        // Same as malloc() except size bytes is an array of dim elements each of elemSize bytes.
        void * aalloc( size_t dim, size_t elemSize ) libcfa_public {
                return doMalloc( dim * elemSize STAT_ARG( AALLOC ) );
        } // aalloc


        // Same as aalloc() with memory set to zero.
        void * calloc( size_t dim, size_t elemSize ) libcfa_public {
                size_t size = dim * elemSize;
                char * addr = (char *)doMalloc( size STAT_ARG( CALLOC ) );

          if ( unlikely( addr == NULL ) ) return NULL;          // stop further processing if 0p is returned

                Heap.Storage.Header * header;
                Heap.FreeHeader * freeHead;
                size_t bsize, alignment;

                #ifndef __CFA_DEBUG__
                bool mapped =
                        #endif // __CFA_DEBUG__
                        headers( "calloc", addr, header, freeHead, bsize, alignment );

                #ifndef __CFA_DEBUG__
                // Mapped storage is zero filled, but in debug mode mapped memory is scrubbed in doMalloc, so it has to be reset to zero.
                if ( likely( ! mapped ) )
                #endif // __CFA_DEBUG__
                        // <-------0000000000000000000000000000UUUUUUUUUUUUUUUUUUUUUUUUU> bsize (bucket size) U => undefined
                        // `-header`-addr                      `-size
                        memset( addr, '\0', size );                                     // set to zeros

                MarkZeroFilledBit( header );                                    // mark as zero fill
                return addr;
        } // calloc


        // Change the size of the memory block pointed to by oaddr to size bytes. The contents are undefined.  If oaddr is
        // 0p, then the call is equivalent to malloc(size), for all values of size; if size is equal to zero, and oaddr is
        // not 0p, then the call is equivalent to free(oaddr). Unless oaddr is 0p, it must have been returned by an earlier
        // call to malloc(), alloc(), calloc() or realloc(). If the area pointed to was moved, a free(oaddr) is done.
        void * resize( void * oaddr, size_t size ) libcfa_public {
          if ( unlikely( oaddr == 0p ) ) {                                      // => malloc( size )
                        return doMalloc( size STAT_ARG( RESIZE ) );
                } // if

                PROLOG( RESIZE, doFree( oaddr ) );                              // => free( oaddr )

                Heap.Storage.Header * header;
                Heap.FreeHeader * freeHead;
                size_t bsize, oalign;
                headers( "resize", oaddr, header, freeHead, bsize, oalign );

                size_t odsize = DataStorage( bsize, oaddr, header ); // data storage available in bucket
                // same size, DO NOT PRESERVE STICKY PROPERTIES.
                if ( oalign == libAlign() && size <= odsize && odsize <= size * 2 ) { // allow 50% wasted storage for smaller size
                        ClearZeroFillBit( header );                                     // no alignment and turn off 0 fill
                        #ifdef __CFA_DEBUG__
                        incUnfreed( size - header->kind.real.size ); // adjustment off the size difference
                        #endif // __CFA_DEBUG__
                        header->kind.real.size = size;                          // reset allocation size
                        #ifdef __STATISTICS__
                        incCalls( RESIZE );
                        #endif // __STATISTICS__
                        return oaddr;
                } // if

                // change size, DO NOT PRESERVE STICKY PROPERTIES.
                doFree( oaddr );                                                                // free previous storage

                return doMalloc( size STAT_ARG( RESIZE ) );             // create new area
        } // resize


        // Same as resize() but the contents are unchanged in the range from the start of the region up to the minimum of
        // the old and new sizes.
        void * realloc( void * oaddr, size_t size ) libcfa_public {
                // char buf[64];
                // int len = sprintf( buf, "realloc1 oaddr %p size %d\n", oaddr, size );
                // write( 2, buf, len );
          if ( unlikely( oaddr == 0p ) ) {                                      // => malloc( size )
                  return doMalloc( size STAT_ARG( REALLOC ) );
                } // if

                PROLOG( REALLOC, doFree( oaddr ) );                             // => free( oaddr )

                Heap.Storage.Header * header;
                Heap.FreeHeader * freeHead;
                size_t bsize, oalign;
                headers( "realloc", oaddr, header, freeHead, bsize, oalign );

                size_t odsize = DataStorage( bsize, oaddr, header ); // data storage available in bucket
                size_t osize = header->kind.real.size;                  // old allocation size
                bool ozfill = ZeroFillBit( header );                    // old allocation zero filled
          if ( unlikely( size <= odsize ) && odsize <= size * 2 ) { // allow up to 50% wasted storage
                        #ifdef __CFA_DEBUG__
                        incUnfreed( size - header->kind.real.size ); // adjustment off the size difference
                        #endif // __CFA_DEBUG__
                        header->kind.real.size = size;                          // reset allocation size
                        if ( unlikely( ozfill ) && size > osize ) {     // previous request zero fill and larger ?
                                memset( (char *)oaddr + osize, '\0', size - osize ); // initialize added storage
                        } // if
                        #ifdef __STATISTICS__
                        incCalls( REALLOC );
                        #endif // __STATISTICS__
                        return oaddr;
                } // if

                // change size and copy old content to new storage

                void * naddr;
                if ( likely( oalign <= libAlign() ) ) {                 // previous request not aligned ?
                        naddr = doMalloc( size STAT_ARG( REALLOC ) ); // create new area
                } else {
                        naddr = memalignNoStats( oalign, size STAT_ARG( REALLOC ) ); // create new aligned area
                } // if

                headers( "realloc", naddr, header, freeHead, bsize, oalign );
                // To preserve prior fill, the entire bucket must be copied versus the size.
                memcpy( naddr, oaddr, min( osize, size ) );             // copy bytes
                doFree( oaddr );                                                                // free previous storage

                if ( unlikely( ozfill ) ) {                                             // previous request zero fill ?
                        MarkZeroFilledBit( header );                            // mark new request as zero filled
                        if ( size > osize ) {                                           // previous request larger ?
                                memset( (char *)naddr + osize, '\0', size - osize ); // initialize added storage
                        } // if
                } // if
                return naddr;
        } // realloc


        // Same as realloc() except the new allocation size is large enough for an array of nelem elements of size elsize.
        void * reallocarray( void * oaddr, size_t dim, size_t elemSize ) libcfa_public {
                return realloc( oaddr, dim * elemSize );
        } // reallocarray


        // Same as malloc() except the memory address is a multiple of alignment, which must be a power of two. (obsolete)
        void * memalign( size_t alignment, size_t size ) libcfa_public {
                return memalignNoStats( alignment, size STAT_ARG( MEMALIGN ) );
        } // memalign


        // Same as aalloc() with memory alignment.
        void * amemalign( size_t alignment, size_t dim, size_t elemSize ) libcfa_public {
                return memalignNoStats( alignment, dim * elemSize STAT_ARG( AMEMALIGN ) );
        } // amemalign


        // Same as calloc() with memory alignment.
        void * cmemalign( size_t alignment, size_t dim, size_t elemSize ) libcfa_public {
                size_t size = dim * elemSize;
                char * addr = (char *)memalignNoStats( alignment, size STAT_ARG( CMEMALIGN ) );

          if ( unlikely( addr == NULL ) ) return NULL;          // stop further processing if 0p is returned

                Heap.Storage.Header * header;
                Heap.FreeHeader * freeHead;
                size_t bsize;

                #ifndef __CFA_DEBUG__
                bool mapped =
                        #endif // __CFA_DEBUG__
                        headers( "cmemalign", addr, header, freeHead, bsize, alignment );

                // Mapped storage is zero filled, but in debug mode mapped memory is scrubbed in doMalloc, so it has to be reset to zero.
                #ifndef __CFA_DEBUG__
                if ( ! mapped )
                #endif // __CFA_DEBUG__
                        // <-------0000000000000000000000000000UUUUUUUUUUUUUUUUUUUUUUUUU> bsize (bucket size) U => undefined
                        // `-header`-addr                      `-size
                        memset( addr, '\0', size );                                     // set to zeros

                MarkZeroFilledBit( header );                                    // mark as zero filled
                return addr;
        } // cmemalign


        // Same as memalign(), but ISO/IEC 2011 C11 Section 7.22.2 states: the value of size shall be an integral multiple
        // of alignment. This requirement is universally ignored.
        void * aligned_alloc( size_t alignment, size_t size ) libcfa_public {
                return memalign( alignment, size );
        } // aligned_alloc


        // Allocates size bytes and places the address of the allocated memory in *memptr. The address of the allocated
        // memory shall be a multiple of alignment, which must be a power of two and a multiple of sizeof(void *). If size
        // is 0, then posix_memalign() returns either 0p, or a unique pointer value that can later be successfully passed to
        // free(3).
        int posix_memalign( void ** memptr, size_t alignment, size_t size ) libcfa_public {
          if ( unlikely( alignment < libAlign() || ! is_pow2( alignment ) ) ) return EINVAL; // check alignment
                *memptr = memalign( alignment, size );
                return 0;
        } // posix_memalign


        // Allocates size bytes and returns a pointer to the allocated memory. The memory address shall be a multiple of the
        // page size.  It is equivalent to memalign(sysconf(_SC_PAGESIZE),size).
        void * valloc( size_t size ) libcfa_public {
                return memalign( __page_size, size );
        } // valloc


        // Same as valloc but rounds size to multiple of page size.
        void * pvalloc( size_t size ) libcfa_public {
                return memalign( __page_size, ceiling2( size, __page_size ) ); // round size to multiple of page size
        } // pvalloc


        // Frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc()
        // or realloc().  Otherwise, or if free(ptr) has already been called before, undefined behaviour occurs. If ptr is
        // 0p, no operation is performed.
        void free( void * addr ) libcfa_public {
          if ( unlikely( addr == 0p ) ) {                                       // special case
                        #ifdef __STATISTICS__
                  if ( heapManager )
                        incZeroCalls( FREE );
                        #endif // __STATISTICS__
                        return;
                } // if

                doFree( addr );                                                                 // handles heapManager == nullptr
        } // free


        // Returns the alignment of an allocation.
        size_t malloc_alignment( void * addr ) libcfa_public {
          if ( unlikely( addr == 0p ) ) return libAlign();      // minimum alignment
                Heap.Storage.Header * header = HeaderAddr( addr );
                if ( unlikely( AlignmentBit( header ) ) ) {             // fake header ?
                        return ClearAlignmentBit( header );                     // clear flag from value
                } else {
                        return libAlign();                                                      // minimum alignment
                } // if
        } // malloc_alignment


        // Returns true if the allocation is zero filled, e.g., allocated by calloc().
        bool malloc_zero_fill( void * addr ) libcfa_public {
          if ( unlikely( addr == 0p ) ) return false;           // null allocation is not zero fill
                Heap.Storage.Header * header = HeaderAddr( addr );
                if ( unlikely( AlignmentBit( header ) ) ) {             // fake header ?
                        header = RealHeader( header );                          // backup from fake to real header
                } // if
                return ZeroFillBit( header );                                   // zero filled ?
        } // malloc_zero_fill


        // Returns original total allocation size (not bucket size) => array size is dimension * sizeof(T).
        size_t malloc_size( void * addr ) libcfa_public {
          if ( unlikely( addr == 0p ) ) return 0;                       // null allocation has zero size
                Heap.Storage.Header * header = HeaderAddr( addr );
                if ( unlikely( AlignmentBit( header ) ) ) {             // fake header ?
                        header = RealHeader( header );                          // backup from fake to real header
                } // if
                return header->kind.real.size;
        } // malloc_size


        // Returns the number of usable bytes in the block pointed to by ptr, a pointer to a block of memory allocated by
        // malloc or a related function.
        size_t malloc_usable_size( void * addr ) libcfa_public {
          if ( unlikely( addr == 0p ) ) return 0;                       // null allocation has 0 size
                Heap.Storage.Header * header;
                Heap.FreeHeader * freeHead;
                size_t bsize, alignment;

                headers( "malloc_usable_size", addr, header, freeHead, bsize, alignment );
                return DataStorage( bsize, addr, header );              // data storage in bucket
        } // malloc_usable_size


        // Prints (on default standard error) statistics about memory allocated by malloc and related functions.
        void malloc_stats( void ) libcfa_public {
                #ifdef __STATISTICS__
                HeapStatistics stats;
                HeapStatisticsCtor( stats );
                if ( printStats( collectStats( stats ) ) == -1 ) {
                #else
                #define MALLOC_STATS_MSG "malloc_stats statistics disabled.\n"
                if ( write( STDERR_FILENO, MALLOC_STATS_MSG, sizeof( MALLOC_STATS_MSG ) - 1 /* size includes '\0' */ ) == -1 ) {
                #endif // __STATISTICS__
                        abort( "**** Error **** write failed in malloc_stats" );
                } // if
        } // malloc_stats


        // Zero the heap master and all active thread heaps.
        void malloc_stats_clear() {
                #ifdef __STATISTICS__
                clearStats();
                #else
                #define MALLOC_STATS_MSG "malloc_stats statistics disabled.\n"
                if ( write( STDERR_FILENO, MALLOC_STATS_MSG, sizeof( MALLOC_STATS_MSG ) - 1 /* size includes '\0' */ ) == -1 ) {
                        abort( "**** Error **** write failed in malloc_stats" );
                } // if
                #endif // __STATISTICS__
        } // malloc_stats_clear

        // Changes the file descriptor where malloc_stats() writes statistics.
        int malloc_stats_fd( int fd __attribute__(( unused )) ) libcfa_public {
                #ifdef __STATISTICS__
                int temp = heapMaster.stats_fd;
                heapMaster.stats_fd = fd;
                return temp;
                #else
                return -1;                                                                              // unsupported
                #endif // __STATISTICS__
        } // malloc_stats_fd


        // Prints an XML string that describes the current state of the memory-allocation implementation in the caller.
        // The string is printed on the file stream stream.  The exported string includes information about all arenas (see
        // malloc).
        int malloc_info( int options, FILE * stream __attribute__(( unused )) ) libcfa_public {
          if ( options != 0 ) { errno = EINVAL; return -1; }
                #ifdef __STATISTICS__
                HeapStatistics stats;
                HeapStatisticsCtor( stats );
                return printStatsXML( collectStats( stats ), stream ); // returns bytes written or -1
                #else
                return 0;                                                                               // unsupported
                #endif // __STATISTICS__
        } // malloc_info


        // Adjusts parameters that control the behaviour of the memory-allocation functions (see malloc). The param argument
        // specifies the parameter to be modified, and value specifies the new value for that parameter.
        int mallopt( int option, int value ) libcfa_public {
          if ( value < 0 ) return 0;
                choose( option ) {
                  case M_TOP_PAD:
                        heapMaster.heapExpand = ceiling2( value, __page_size );
                        return 1;
                  case M_MMAP_THRESHOLD:
                        if ( setMmapStart( value ) ) return 1;
                } // choose
                return 0;                                                                               // error, unsupported
        } // mallopt


        // Attempt to release free memory at the top of the heap (by calling sbrk with a suitable argument).
        int malloc_trim( size_t ) libcfa_public {
                return 0;                                                                               // => impossible to release memory
        } // malloc_trim


        // Records the current state of all malloc internal bookkeeping variables (but not the actual contents of the heap
        // or the state of malloc_hook functions pointers).  The state is recorded in a system-dependent opaque data
        // structure dynamically allocated via malloc, and a pointer to that data structure is returned as the function
        // result.  (The caller must free this memory.)
        void * malloc_get_state( void ) libcfa_public {
                return 0p;                                                                              // unsupported
        } // malloc_get_state


        // Restores the state of all malloc internal bookkeeping variables to the values recorded in the opaque data
        // structure pointed to by state.
        int malloc_set_state( void * ) libcfa_public {
                return 0;                                                                               // unsupported
        } // malloc_set_state


        // Sets the amount (bytes) to extend the heap when there is insufficent free storage to service an allocation.
        __attribute__((weak)) size_t malloc_expansion() libcfa_public { return __CFA_DEFAULT_HEAP_EXPANSION__; }

        // Sets the crossover point between allocations occuring in the sbrk area or separately mmapped.
        __attribute__((weak)) size_t malloc_mmap_start() libcfa_public { return __CFA_DEFAULT_MMAP_START__; }

        // Amount subtracted to adjust for unfreed program storage (debug only).
        __attribute__((weak)) size_t malloc_unfreed() libcfa_public { return __CFA_DEFAULT_HEAP_UNFREED__; }
} // extern "C"


// Must have CFA linkage to overload with C linkage realloc.
void * resize( void * oaddr, size_t nalign, size_t size ) libcfa_public {
  if ( unlikely( oaddr == 0p ) ) {                                              // => malloc( size )
                return memalignNoStats( nalign, size STAT_ARG( RESIZE ) );
        } // if

        PROLOG( RESIZE, doFree( oaddr ) );                                      // => free( oaddr )

        // Attempt to reuse existing alignment.
        Heap.Storage.Header * header = HeaderAddr( oaddr );
        bool isFakeHeader = AlignmentBit( header );                     // old fake header ?
        size_t oalign;

        if ( unlikely( isFakeHeader ) ) {
                checkAlign( nalign );                                                   // check alignment
                oalign = ClearAlignmentBit( header );                   // old alignment
                if ( unlikely( (uintptr_t)oaddr % nalign == 0   // lucky match ?
                         && ( oalign <= nalign                                          // going down
                                  || (oalign >= nalign && oalign <= 256) ) // little alignment storage wasted ?
                        ) ) {
                        HeaderAddr( oaddr )->kind.fake.alignment = MarkAlignmentBit( nalign ); // update alignment (could be the same)
                        Heap.FreeHeader * freeHead;
                        size_t bsize, oalign;
                        headers( "resize", oaddr, header, freeHead, bsize, oalign );
                        size_t odsize = DataStorage( bsize, oaddr, header ); // data storage available in bucket

                        if ( size <= odsize && odsize <= size * 2 ) { // allow 50% wasted data storage
                                HeaderAddr( oaddr )->kind.fake.alignment = MarkAlignmentBit( nalign ); // update alignment (could be the same)
                                ClearZeroFillBit( header );                             // turn off 0 fill
                                #ifdef __CFA_DEBUG__
                                incUnfreed( size - header->kind.real.size ); // adjustment off the size difference
                                #endif // __CFA_DEBUG__
                                header->kind.real.size = size;                  // reset allocation size
                                #ifdef __STATISTICS__
                                incCalls( RESIZE );
                                #endif // __STATISTICS__
                                return oaddr;
                        } // if
                } // if
        } else if ( ! isFakeHeader                                                      // old real header (aligned on libAlign) ?
                                && nalign == libAlign() ) {                             // new alignment also on libAlign => no fake header needed
                return resize( oaddr, size );                                   // duplicate special case checks
        } // if

        // change size, DO NOT PRESERVE STICKY PROPERTIES.
        doFree( oaddr );                                                                        // free previous storage
        return memalignNoStats( nalign, size STAT_ARG( RESIZE ) ); // create new aligned area
} // resize


void * realloc( void * oaddr, size_t nalign, size_t size ) libcfa_public {
        // char buf[64];
        // int len = sprintf( buf, "realloc2 oaddr %p size %d\n", oaddr, size );
        // write( 2, buf, len );
  if ( unlikely( oaddr == 0p ) ) {                                              // => malloc( size )
                return memalignNoStats( nalign, size STAT_ARG( REALLOC ) );
        } // if

        PROLOG( REALLOC, doFree( oaddr ) );                                     // => free( oaddr )

        // Attempt to reuse existing alignment.
        Heap.Storage.Header * header = HeaderAddr( oaddr );
        bool isFakeHeader = AlignmentBit( header );                     // old fake header ?
        size_t oalign;
        if ( unlikely( isFakeHeader ) ) {
                checkAlign( nalign );                                                   // check alignment
                oalign = ClearAlignmentBit( header );                   // old alignment
                if ( unlikely( (uintptr_t)oaddr % nalign == 0   // lucky match ?
                         && ( oalign <= nalign                                          // going down
                                  || (oalign >= nalign && oalign <= 256) ) // little alignment storage wasted ?
                        ) ) {
                        HeaderAddr( oaddr )->kind.fake.alignment = MarkAlignmentBit( nalign ); // update alignment (could be the same)
                        return realloc( oaddr, size );                          // duplicate special case checks
                } // if
        } else if ( ! isFakeHeader                                                      // old real header (aligned on libAlign) ?
                                && nalign == libAlign() ) {                             // new alignment also on libAlign => no fake header needed
                return realloc( oaddr, size );                                  // duplicate special case checks
        } // if

        Heap.FreeHeader * freeHead;
        size_t bsize;
        headers( "realloc", oaddr, header, freeHead, bsize, oalign );

        // change size and copy old content to new storage

        size_t osize = header->kind.real.size;                          // old allocation size
        bool ozfill = ZeroFillBit( header );                            // old allocation zero filled

        void * naddr = memalignNoStats( nalign, size STAT_ARG( REALLOC ) ); // create new aligned area

        headers( "realloc", naddr, header, freeHead, bsize, oalign );
        memcpy( naddr, oaddr, min( osize, size ) );                     // copy bytes
        doFree( oaddr );                                                                        // free previous storage

        if ( unlikely( ozfill ) ) {                                                     // previous request zero fill ?
                MarkZeroFilledBit( header );                                    // mark new request as zero filled
                if ( size > osize ) {                                                   // previous request larger ?
                        memset( (char *)naddr + osize, '\0', size - osize ); // initialize added storage
                } // if
        } // if
        return naddr;
} // realloc


void * reallocarray( void * oaddr, size_t nalign, size_t dim, size_t elemSize ) __THROW {
        return realloc( oaddr, nalign, dim * elemSize );
} // reallocarray


// Local Variables: //
// tab-width: 4 //
// compile-command: "cfa -nodebug -O2 heap.cfa" //
// End: //