source: src/libcfa/concurrency/coroutine.c @ 6c7c63c

//
// 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.
//
// coroutine.c --
//
// Author           : Thierry Delisle
// Created On       : Mon Nov 28 12:27:26 2016
// Last Modified By : Peter A. Buhr
// Last Modified On : Thu Feb  8 16:10:31 2018
// Update Count     : 4
//

#include "coroutine"

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

#include "kernel_private.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

//-----------------------------------------------------------------------------
// Coroutine ctors and dtors
void ?{}(coStack_t& this) with( this ) {
        size            = 65000;        // size of stack
        storage = NULL; // pointer to stack
        limit           = NULL; // stack grows towards stack limit
        base            = NULL; // base of stack
        context = NULL; // address of cfa_context_t
        top             = NULL; // address of top of storage
        userStack       = false;
}

void ?{}(coStack_t& this, size_t size) {
        this{};
        this.size = size;

        create_stack(&this, this.size);
}

void ?{}(coroutine_desc& this) {
        this{ "Anonymous Coroutine" };
}

void ?{}(coroutine_desc& this, const char * name) with( this ) {
        this.name = name;
        errno_ = 0;
        state = Start;
        starter = NULL;
        last = NULL;
}

void ?{}(coroutine_desc& this, size_t size) {
        this{};
        (this.stack){size};
}

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

void ^?{}(coroutine_desc& 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_desc* this = get_coroutine(cor);
        assert(this->state == Start);

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

// Wrapper for co
void CoroutineCtxSwitch(coroutine_desc* src, coroutine_desc* dst) {
        verify( preemption.enabled || this_processor->do_terminate );
        disable_interrupts();

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

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

        // context switch to specified coroutine
        assert( src->stack.context );
        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;

        enable_interrupts( __cfaabi_dbg_ctx );
        verify( preemption.enabled || this_processor->do_terminate );
} //ctxSwitchDirect

void create_stack( coStack_t* this, unsigned int storageSize ) with( *this ) {
        //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)storage == 0 ) {
                userStack = false;
                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
                __cfaabi_dbg_debug_do( storage = memalign( pageSize, cxtSize + size + pageSize ) );
                __cfaabi_dbg_no_debug_do( storage = malloc( cxtSize + size + 8 ) );

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

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

                __cfaabi_dbg_debug_do( limit = (char *)storage + pageSize );
                __cfaabi_dbg_no_debug_do( limit = (char *)libCeiling( (unsigned long)storage, 16 ) ); // minimum alignment

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

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

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

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

// We need to call suspend from invoke.c, so we expose this wrapper that
// is not inline (We can't inline Cforall in C)
extern "C" {
        void __suspend_internal(void) {
                suspend();
        }

        void __leave_coroutine(void) {
                coroutine_desc * src = this_coroutine;          // optimization

                assertf( src->starter != 0,
                        "Attempt to suspend/leave 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->starter->state != Halted,
                        "Attempt by coroutine \"%.256s\" (%p) to suspend/leave back to terminated coroutine \"%.256s\" (%p).\n"
                        "Possible cause is terminated coroutine's main routine has already returned.",
                        src->name, src, src->starter->name, src->starter );

                CoroutineCtxSwitch( src, src->starter );
        }
}

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