source: src/libcfa/concurrency/threads.c@ fa66f4e

//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// threads.c --
//
// Author           : Thierry Delisle
// Created On       : Mon Nov 28 12:27:26 2016
// Last Modified By : Thierry Delisle
// Last Modified On : Mon Nov 28 12:27:26 2016
// Update Count     : 0
//

extern "C" {
#include <stddef.h>
#include <malloc.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
}

#include "threads"
#include "assert"
#include "libhdr.h"

extern "C" { extern void coInvokeStub( void ); }

// minimum feasible stack size in bytes
#define MinStackSize 1000

static coroutine main_coroutine;
static coroutine* current_coroutine = &main_coroutine;

extern "C" {
        struct machine_context_t {
                void *SP;
                void *FP;
                void *PC;
        };
}

extern "C" { void CtxSwitch( void *from, void *to ) asm ("CtxSwitch"); }// assembler routine that performs the context switch

static size_t pageSize = 0;                             // architecture pagesize

void ctxSwitchDirect(coroutine* src, coroutine* dst) {
        // THREAD_GETMEM( This )->disableInterrupts();

        // set state of current coroutine to inactive
        src->state = Inactive;

        // set new coroutine that task is executing
        current_coroutine = dst;                        

        // context switch to specified coroutine
        CtxSwitch( src->stack.context, dst->stack.context );
        // when CtxSwitch returns we are back in the src coroutine              

        // set state of new coroutine to active
        src->state = Active;

        // THREAD_GETMEM( This )->enableInterrupts();
} //ctxSwitchDirect

void invokeCoroutine(coVtable* vtable, void* this);

forall(dtype T | coroutine_t(T))
void startCoroutine(T* this, void (*invoke)(coVtable*, void*));

// used by all constructors
void create_stack( coStack_t* this, unsigned int storageSize ) {
        //TEMP HACK do this on proper kernel startup
        if(pageSize == 0ul) pageSize = sysconf( _SC_PAGESIZE );

        size_t cxtSize = libCeiling( sizeof(machine_context_t), 8 ); // minimum alignment

        if ( (intptr_t)this->storage == 0 ) {
                this->userStack = false;
                this->size = libCeiling( storageSize, 16 );
                // use malloc/memalign because "new" raises an exception for out-of-memory
                
                // assume malloc has 8 byte alignment so add 8 to allow rounding up to 16 byte alignment
                LIB_DEBUG_DO( this->storage = memalign( pageSize, cxtSize + this->size + pageSize ) );
                LIB_NO_DEBUG_DO( this->storage = malloc( cxtSize + this->size + 8 ) );

                LIB_DEBUG_DO(
                        if ( mprotect( this->storage, pageSize, PROT_NONE ) == -1 ) {
                                abortf( "(uMachContext &)%p.createContext() : internal error, mprotect failure, error(%d) %s.", this, (int)errno, strerror( (int)errno ) );
                        } // if
                );

                if ( (intptr_t)this->storage == 0 ) {
                        abortf( "Attempt to allocate %d bytes of storage for coroutine or task execution-state but insufficient memory available.", this->size );
                } // if

                LIB_DEBUG_DO( this->limit = (char *)this->storage + pageSize );
                LIB_NO_DEBUG_DO( this->limit = (char *)libCeiling( (unsigned long)this->storage, 16 ) ); // minimum alignment

        } else {
                assertf( ((size_t)this->storage & (libAlign() - 1)) != 0ul, "Stack storage %p for task/coroutine must be aligned on %d byte boundary.", this->storage, (int)libAlign() );
                this->userStack = true;
                this->size = storageSize - cxtSize;

                if ( this->size % 16 != 0u ) this->size -= 8;

                this->limit = (char *)libCeiling( (unsigned long)this->storage, 16 ); // minimum alignment
        } // if
        assertf( this->size >= MinStackSize, "Stack size %d provides less than minimum of %d bytes for a stack.", this->size, MinStackSize );

        this->base = (char *)this->limit + this->size;
        this->context = this->base;
        this->top = (char *)this->context + cxtSize;
}

coroutine* this_coroutine() {
        return current_coroutine;
}

void ?{}(coStack_t* this) {
        this->size              = 10240;        // size of stack
        this->storage   = NULL; // pointer to stack
        this->limit             = NULL; // stack grows towards stack limit
        this->base              = NULL; // base of stack
        this->context   = NULL; // address of cfa_context_t
        this->top               = NULL; // address of top of storage
        this->userStack = false;        
        create_stack(this, this->size);
}

void ?{}(coroutine* this)
{
        this->name = "Anonymous Coroutine";
        this->errno_ = 0;
        this->state = Start;
      this->notHalted = true;
        this->starter = NULL;
        this->last = NULL;
}

forall(dtype T | coroutine_t(T))
void start(T* this) {
        startCoroutine(this, invokeCoroutine);
}

void suspend() {
      coroutine* src = this_coroutine();                // optimization

        assertf( src->last != 0, 
                "Attempt to suspend coroutine %.256s (%p) that has never been resumed.\n"
                "Possible cause is a suspend executed in a member called by a coroutine user rather than by the coroutine main.",
                src->name, src );
        assertf( src->last->notHalted, 
                "Attempt by coroutine %.256s (%p) to suspend back to terminated coroutine %.256s (%p).\n"
                "Possible cause is terminated coroutine's main routine has already returned.",
                src->name, src, src->last->name, src->last );

        ctxSwitchDirect( src, src->last );
}

forall(dtype T | coroutine_t(T))
void resume(T* cor) {
        coroutine* src = this_coroutine();              // optimization
        coroutine* dst = this_coroutine(cor);

        if ( src != dst ) {                             // not resuming self ?
                assertf( dst->notHalted , 
                        "Attempt by coroutine %.256s (%p) to resume terminated coroutine %.256s (%p).\n"
                        "Possible cause is terminated coroutine's main routine has already returned.",
                        src->name, src, dst->name, dst );
                dst->last = src;                                        // set last resumer
        } // if
        ctxSwitchDirect( src, dst );                            // always done for performance testing
}

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