source: src/libcfa/concurrency/coroutines.c @ c49bf54

//
// 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.
//
// coroutines.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 "coroutines"
#include "libhdr.h"

#define __CFA_INVOKE_PRIVATE__
#include "invoke.h"

//-----------------------------------------------------------------------------
// Global state variables

// minimum feasible stack size in bytes
#define MinStackSize 1000
static size_t pageSize = 0;                             // architecture pagesize HACK, should go in proper runtime singleton

//Extra private desctructor for the main
//FIXME the main should not actually allocate a stack
//Since the main is never resumed the extra stack does not cause 
//any problem but it is wasted memory
void ?{}(coStack_t* this, size_t size);
void ?{}(coroutine* this, size_t size);

//Main coroutine
//FIXME do not construct a stack for the main
coroutine main_coroutine = { 1000 };

//Current coroutine
//Will need to be in TLS when multi-threading is added
coroutine* current_coroutine = &main_coroutine;

//-----------------------------------------------------------------------------
// Coroutine ctors and dtors
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;        
}

void ?{}(coStack_t* this, size_t size) {
        this{};
        this->size = size;

        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;
}

void ?{}(coroutine* this, size_t size) {
        this{};
        (&this->stack){size};
}

void ^?{}(coStack_t* this) {
        if ( ! this->userStack ) {
                LIB_DEBUG_DO(
                        if ( mprotect( this->storage, pageSize, PROT_READ | PROT_WRITE ) == -1 ) {
                                abortf( "(coStack_t *)%p.^?{}() : internal error, mprotect failure, error(%d) %s.", this, errno, strerror( errno ) );
                        }
                );
                free( this->storage );
        }
}

void ^?{}(coroutine* this) {}

// Part of the Public API
// Not inline since only ever called once per coroutine
forall(dtype T | is_coroutine(T))
void prime(T* cor) {
        coroutine* this = get_coroutine(cor);
        assert(this->state == Start);

        this->state = Primed;
        resume(cor);
}

// We need to call suspend from invoke.c, so we expose this wrapper that
// is not inline (We can't inline Cforall in C)
void suspend_no_inline(void) {
        LIB_DEBUG_PRINTF("Suspending back : to %p from %p\n", this_coroutine(), this_coroutine() ? this_coroutine()->last : (void*)-1);

        suspend();
}

void corCxtSw(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 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;
}

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