critical.c

/**
 * Implementation of support routines for synchronized blocks.
 *
 * Copyright: Copyright Digital Mars 2000 - 2010.
 * License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
 * Authors:   Walter Bright, Sean Kelly
 */

/*          Copyright Digital Mars 2000 - 2010.
 * Distributed under the Boost Software License, Version 1.0.
 *    (See accompanying file LICENSE or copy at
 *          http://www.boost.org/LICENSE_1_0.txt)
 */

/* ================================= Win32 ============================ */

#if _WIN32

#include <windows.h>

/******************************************
 * Enter/exit critical section.
 */

/* We don't initialize critical sections unless we actually need them.
 * So keep a linked list of the ones we do use, and in the static destructor
 * code, walk the list and release them.
 */

typedef struct D_CRITICAL_SECTION
{
    struct D_CRITICAL_SECTION *next;
    CRITICAL_SECTION cs;
} D_CRITICAL_SECTION;

static D_CRITICAL_SECTION *dcs_list;
static D_CRITICAL_SECTION critical_section;
static volatile int inited;

void _d_criticalenter(D_CRITICAL_SECTION *dcs)
{
    if (!dcs->next)
    {
        EnterCriticalSection(&critical_section.cs);
        if (!dcs->next) // if, in the meantime, another thread didn't set it
        {
            dcs->next = dcs_list;
            dcs_list = dcs;
            InitializeCriticalSection(&dcs->cs);
        }
        LeaveCriticalSection(&critical_section.cs);
    }
    EnterCriticalSection(&dcs->cs);
}

void _d_criticalexit(D_CRITICAL_SECTION *dcs)
{
    LeaveCriticalSection(&dcs->cs);
}

void _STI_critical_init()
{
    if (!inited)
    {   InitializeCriticalSection(&critical_section.cs);
        dcs_list = &critical_section;
        inited = 1;
    }
}

void _STD_critical_term()
{
    if (inited)
    {   inited = 0;
        while (dcs_list)
        {
            DeleteCriticalSection(&dcs_list->cs);
            dcs_list = dcs_list->next;
        }
    }
}

#endif

/* ================================= linux ============================ */

#if linux || __APPLE__ || __FreeBSD__

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

// PTHREAD_MUTEX_RECURSIVE is the "standard" symbol,
// while the _NP version is specific to Linux
#if linux
#  ifndef PTHREAD_MUTEX_RECURSIVE
#    define PTHREAD_MUTEX_RECURSIVE PTHREAD_MUTEX_RECURSIVE_NP
#  endif
#endif

/******************************************
 * Enter/exit critical section.
 */

/* We don't initialize critical sections unless we actually need them.
 * So keep a linked list of the ones we do use, and in the static destructor
 * code, walk the list and release them.
 */

typedef struct D_CRITICAL_SECTION
{
    struct D_CRITICAL_SECTION *next;
    pthread_mutex_t cs;
} D_CRITICAL_SECTION;

static D_CRITICAL_SECTION *dcs_list;
static D_CRITICAL_SECTION critical_section;
static pthread_mutexattr_t _criticals_attr;

void _STI_critical_init(void);
void _STD_critical_term(void);

void _d_criticalenter(D_CRITICAL_SECTION *dcs)
{
    if (!dcs_list)
    {   _STI_critical_init();
        atexit(_STD_critical_term);
    }
    //printf("_d_criticalenter(dcs = x%x)\n", dcs);
    if (!dcs->next)
    {
        pthread_mutex_lock(&critical_section.cs);
        if (!dcs->next) // if, in the meantime, another thread didn't set it
        {
            dcs->next = dcs_list;
            dcs_list = dcs;
            pthread_mutex_init(&dcs->cs, &_criticals_attr);
        }
        pthread_mutex_unlock(&critical_section.cs);
    }
    pthread_mutex_lock(&dcs->cs);
}

void _d_criticalexit(D_CRITICAL_SECTION *dcs)
{
    //printf("_d_criticalexit(dcs = x%x)\n", dcs);
    pthread_mutex_unlock(&dcs->cs);
}

void _STI_critical_init()
{
    if (!dcs_list)
    {   //printf("_STI_critical_init()\n");
        pthread_mutexattr_init(&_criticals_attr);
        pthread_mutexattr_settype(&_criticals_attr, PTHREAD_MUTEX_RECURSIVE);

        // The global critical section doesn't need to be recursive
        pthread_mutex_init(&critical_section.cs, 0);
        dcs_list = &critical_section;
    }
}

void _STD_critical_term()
{
    if (dcs_list)
    {   //printf("_STI_critical_term()\n");
        while (dcs_list)
        {
            //printf("\tlooping... %x\n", dcs_list);
            pthread_mutex_destroy(&dcs_list->cs);
            dcs_list = dcs_list->next;
        }
    }
}

#endif