pruthr.c

Netscape NSPR库源码

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape Portable Runtime (NSPR).
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1998-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */

#include "primpl.h"
#include <signal.h>
#include <string.h>

#if defined(WIN95)                                                                         
/*
** Some local variables report warnings on Win95 because the code paths
** using them are conditioned on HAVE_CUSTOME_USER_THREADS.
** The pragma suppresses the warning.
**
*/
#pragma warning(disable : 4101)
#endif          

#if defined(XP_MAC)
#include <LowMem.h>
#endif

/* _pr_activeLock protects the following global variables */
PRLock *_pr_activeLock;
PRInt32 _pr_primordialExitCount;   /* In PR_Cleanup(), the primordial thread
                    * waits until all other user (non-system)
                    * threads have terminated before it exits.
                    * So whenever we decrement _pr_userActive,
                    * it is compared with
                    * _pr_primordialExitCount.
                    * If the primordial thread is a system
                    * thread, then _pr_primordialExitCount
                    * is 0.  If the primordial thread is
                    * itself a user thread, then 
                    * _pr_primordialThread is 1.
                    */
PRCondVar *_pr_primordialExitCVar; /* When _pr_userActive is decremented to
                    * _pr_primordialExitCount, this condition
                    * variable is notified.
                    */

PRLock *_pr_deadQLock;
PRUint32 _pr_numNativeDead;
PRUint32 _pr_numUserDead;
PRCList _pr_deadNativeQ;
PRCList _pr_deadUserQ;

PRUint32 _pr_join_counter;

PRUint32 _pr_local_threads;
PRUint32 _pr_global_threads;

PRBool suspendAllOn = PR_FALSE;
PRThread *suspendAllThread = NULL;

extern PRCList _pr_active_global_threadQ;
extern PRCList _pr_active_local_threadQ;

static void _PR_DecrActiveThreadCount(PRThread *thread);
static PRThread *_PR_AttachThread(PRThreadType, PRThreadPriority, PRThreadStack *);
static void _PR_InitializeNativeStack(PRThreadStack *ts);
static void _PR_InitializeRecycledThread(PRThread *thread);
static void _PR_UserRunThread(void);

void _PR_InitThreads(PRThreadType type, PRThreadPriority priority,
    PRUintn maxPTDs)
{
#if defined(XP_MAC)
#pragma unused (maxPTDs)
#endif

    PRThread *thread;
    PRThreadStack *stack;

    _pr_terminationCVLock = PR_NewLock();
    _pr_activeLock = PR_NewLock();

#ifndef HAVE_CUSTOM_USER_THREADS
    stack = PR_NEWZAP(PRThreadStack);
#ifdef HAVE_STACK_GROWING_UP
    stack->stackTop = (char*) ((((long)&type) >> _pr_pageShift)
                  << _pr_pageShift);
#else
#if defined(SOLARIS) || defined (UNIXWARE) && defined (USR_SVR4_THREADS)
    stack->stackTop = (char*) &thread;
#elif defined(XP_MAC)
    stack->stackTop = (char*) LMGetCurStackBase();
#else
    stack->stackTop = (char*) ((((long)&type + _pr_pageSize - 1)
                >> _pr_pageShift) << _pr_pageShift);
#endif
#endif
#else
    /* If stack is NULL, we're using custom user threads like NT fibers. */
    stack = PR_NEWZAP(PRThreadStack);
    if (stack) {
        stack->stackSize = 0;
        _PR_InitializeNativeStack(stack);
    }
#endif /* HAVE_CUSTOM_USER_THREADS */

    thread = _PR_AttachThread(type, priority, stack);
    if (thread) {
        _PR_MD_SET_CURRENT_THREAD(thread);

        if (type == PR_SYSTEM_THREAD) {
            thread->flags = _PR_SYSTEM;
            _pr_systemActive++;
            _pr_primordialExitCount = 0;
        } else {
            _pr_userActive++;
            _pr_primordialExitCount = 1;
        }
    thread->no_sched = 1;
    _pr_primordialExitCVar = PR_NewCondVar(_pr_activeLock);
    }

    if (!thread) PR_Abort();
#ifdef _PR_LOCAL_THREADS_ONLY
    thread->flags |= _PR_PRIMORDIAL;
#else
    thread->flags |= _PR_PRIMORDIAL | _PR_GLOBAL_SCOPE;
#endif

    /*
     * Needs _PR_PRIMORDIAL flag set before calling
     * _PR_MD_INIT_THREAD()
     */
    if (_PR_MD_INIT_THREAD(thread) == PR_FAILURE) {
        /*
         * XXX do what?
         */
    }

    if (_PR_IS_NATIVE_THREAD(thread)) {
        PR_APPEND_LINK(&thread->active, &_PR_ACTIVE_GLOBAL_THREADQ());
        _pr_global_threads++;
    } else {
        PR_APPEND_LINK(&thread->active, &_PR_ACTIVE_LOCAL_THREADQ());
        _pr_local_threads++;
    }

    _pr_recycleThreads = 0;
    _pr_deadQLock = PR_NewLock();
    _pr_numNativeDead = 0;
    _pr_numUserDead = 0;
    PR_INIT_CLIST(&_pr_deadNativeQ);
    PR_INIT_CLIST(&_pr_deadUserQ);
}

void _PR_CleanupThreads(void)
{
    if (_pr_terminationCVLock) {
        PR_DestroyLock(_pr_terminationCVLock);
        _pr_terminationCVLock = NULL;
    }
    if (_pr_activeLock) {
        PR_DestroyLock(_pr_activeLock);
        _pr_activeLock = NULL;
    }
    if (_pr_primordialExitCVar) {
        PR_DestroyCondVar(_pr_primordialExitCVar);
        _pr_primordialExitCVar = NULL;
    }
    /* TODO _pr_dead{Native,User}Q need to be deleted */
    if (_pr_deadQLock) {
        PR_DestroyLock(_pr_deadQLock);
        _pr_deadQLock = NULL;
    }
}

/*
** Initialize a stack for a native thread
*/
static void _PR_InitializeNativeStack(PRThreadStack *ts)
{
    if( ts && (ts->stackTop == 0) ) {
        ts->allocSize = ts->stackSize;

        /*
        ** Setup stackTop and stackBottom values.
        */
#ifdef HAVE_STACK_GROWING_UP
    ts->allocBase = (char*) ((((long)&ts) >> _pr_pageShift)
                  << _pr_pageShift);
        ts->stackBottom = ts->allocBase + ts->stackSize;
        ts->stackTop = ts->allocBase;
#else
        ts->allocBase = (char*) ((((long)&ts + _pr_pageSize - 1)
                >> _pr_pageShift) << _pr_pageShift);
        ts->stackTop    = ts->allocBase;
        ts->stackBottom = ts->allocBase - ts->stackSize;
#endif
    }
}

void _PR_NotifyJoinWaiters(PRThread *thread)
{
    /*
    ** Handle joinable threads.  Change the state to waiting for join.
    ** Remove from our run Q and put it on global waiting to join Q.
    ** Notify on our "termination" condition variable so that joining
    ** thread will know about our termination.  Switch our context and
    ** come back later on to continue the cleanup.
    */    
    PR_ASSERT(thread == _PR_MD_CURRENT_THREAD());
    if (thread->term != NULL) {
        PR_Lock(_pr_terminationCVLock);
        _PR_THREAD_LOCK(thread);
        thread->state = _PR_JOIN_WAIT;
        if ( !_PR_IS_NATIVE_THREAD(thread) ) {
            _PR_MISCQ_LOCK(thread->cpu);
            _PR_ADD_JOINQ(thread, thread->cpu);
            _PR_MISCQ_UNLOCK(thread->cpu);
        }
        _PR_THREAD_UNLOCK(thread);
        PR_NotifyCondVar(thread->term);
        PR_Unlock(_pr_terminationCVLock);
        _PR_MD_WAIT(thread, PR_INTERVAL_NO_TIMEOUT);
        PR_ASSERT(thread->state != _PR_JOIN_WAIT);
    }

}

/*
 * Zero some of the data members of a recycled thread.
 *
 * Note that we can do this either when a dead thread is added to
 * the dead thread queue or when it is reused.  Here, we are doing
 * this lazily, when the thread is reused in _PR_CreateThread().
 */
static void _PR_InitializeRecycledThread(PRThread *thread)
{
    /*
     * Assert that the following data members are already zeroed
     * by _PR_CleanupThread().
     */
#ifdef DEBUG
    if (thread->privateData) {
        unsigned int i;
        for (i = 0; i < thread->tpdLength; i++) {
            PR_ASSERT(thread->privateData[i] == NULL);
        }
    }
#endif
    PR_ASSERT(thread->dumpArg == 0 && thread->dump == 0);
    PR_ASSERT(thread->errorString == 0 && thread->errorStringSize == 0);
    PR_ASSERT(thread->errorStringLength == 0);

    /* Reset data members in thread structure */
    thread->errorCode = thread->osErrorCode = 0;
    thread->io_pending = thread->io_suspended = PR_FALSE;
    thread->environment = 0;
    PR_INIT_CLIST(&thread->lockList);
}

PRStatus _PR_RecycleThread(PRThread *thread)
{
    if ( _PR_IS_NATIVE_THREAD(thread) &&
            _PR_NUM_DEADNATIVE < _pr_recycleThreads) {
        _PR_DEADQ_LOCK;
        PR_APPEND_LINK(&thread->links, &_PR_DEADNATIVEQ);
        _PR_INC_DEADNATIVE;
        _PR_DEADQ_UNLOCK;
    return (PR_SUCCESS);
    } else if ( !_PR_IS_NATIVE_THREAD(thread) &&
                _PR_NUM_DEADUSER < _pr_recycleThreads) {
        _PR_DEADQ_LOCK;
        PR_APPEND_LINK(&thread->links, &_PR_DEADUSERQ);
        _PR_INC_DEADUSER;
        _PR_DEADQ_UNLOCK;
    return (PR_SUCCESS);
    }
    return (PR_FAILURE);
}

/*
 * Decrement the active thread count, either _pr_systemActive or
 * _pr_userActive, depending on whether the thread is a system thread
 * or a user thread.  If all the user threads, except possibly
 * the primordial thread, have terminated, we notify the primordial
 * thread of this condition.
 *
 * Since this function will lock _pr_activeLock, do not call this
 * function while holding the _pr_activeLock lock, as this will result
 * in a deadlock.
 */

static void
_PR_DecrActiveThreadCount(PRThread *thread)
{
    PR_Lock(_pr_activeLock);
    if (thread->flags & _PR_SYSTEM) {
        _pr_systemActive--;
    } else {
        _pr_userActive--;
        if (_pr_userActive == _pr_primordialExitCount) {
            PR_NotifyCondVar(_pr_primordialExitCVar);
        }
    }
    PR_Unlock(_pr_activeLock);
}

/*
** Detach thread structure
*/
static void
_PR_DestroyThread(PRThread *thread)
{
    _PR_MD_FREE_LOCK(&thread->threadLock);
    PR_DELETE(thread);
}

void
_PR_NativeDestroyThread(PRThread *thread)
{
    if(thread->term) {
        PR_DestroyCondVar(thread->term);
        thread->term = 0;
    }
    if (NULL != thread->privateData) {
        PR_ASSERT(0 != thread->tpdLength);
        PR_DELETE(thread->privateData);
        thread->tpdLength = 0;
    }
    PR_DELETE(thread->stack);
    _PR_DestroyThread(thread);
}

void
_PR_UserDestroyThread(PRThread *thread)
{
    if(thread->term) {
        PR_DestroyCondVar(thread->term);
        thread->term = 0;
    }
    if (NULL != thread->privateData) {
        PR_ASSERT(0 != thread->tpdLength);
        PR_DELETE(thread->privateData);
        thread->tpdLength = 0;
    }
    _PR_MD_FREE_LOCK(&thread->threadLock);
    if (thread->threadAllocatedOnStack == 1) {
        _PR_MD_CLEAN_THREAD(thread);
        /*
         *  Because the no_sched field is set, this thread/stack will
         *  will not be re-used until the flag is cleared by the thread
         *  we will context switch to.
         */
        _PR_FreeStack(thread->stack);
    } else {
#ifdef WINNT
        _PR_MD_CLEAN_THREAD(thread);
#else
        /*
         * This assertion does not apply to NT.  On NT, every fiber
         * has its threadAllocatedOnStack equal to 0.  Elsewhere,
         * only the primordial thread has its threadAllocatedOnStack
         * equal to 0.
         */
        PR_ASSERT(thread->flags & _PR_PRIMORDIAL);
#endif
    }
}


/*
** Run a thread's start function. When the start function returns the
** thread is done executing and no longer needs the CPU. If there are no
** more user threads running then we can exit the program.
*/
void _PR_NativeRunThread(void *arg)
{
    PRThread *thread = (PRThread *)arg;

    _PR_MD_SET_CURRENT_THREAD(thread);

    _PR_MD_SET_CURRENT_CPU(NULL);

    /* Set up the thread stack information */
    _PR_InitializeNativeStack(thread->stack);

    /* Set up the thread md information */
    if (_PR_MD_INIT_THREAD(thread) == PR_FAILURE) {
        /*
         * thread failed to initialize itself, possibly due to
         * failure to allocate per-thread resources
         */
        return;
    }

    while(1) {
        thread->state = _PR_RUNNING;

        /*
         * Add to list of active threads
         */
        PR_Lock(_pr_activeLock);
        PR_APPEND_LINK(&thread->active, &_PR_ACTIVE_GLOBAL_THREADQ());
        _pr_global_threads++;
        PR_Unlock(_pr_activeLock);

        (*thread->startFunc)(thread->arg);

        /*
         * The following two assertions are meant for NT asynch io.
         *
         * The thread should have no asynch io in progress when it
         * exits, otherwise the overlapped buffer, which is part of
         * the thread structure, would become invalid.
         */
        PR_ASSERT(thread->io_pending == PR_FALSE);
        /*
         * This assertion enforces the programming guideline that
         * if an io function times out or is interrupted, the thread
         * should close the fd to force the asynch io to abort
         * before it exits.  Right now, closing the fd is the only
         * way to clear the io_suspended flag.
         */
        PR_ASSERT(thread->io_suspended == PR_FALSE);

        /*
         * remove thread from list of active threads
         */
        PR_Lock(_pr_activeLock);
        PR_REMOVE_LINK(&thread->active);
        _pr_global_threads--;
        PR_Unlock(_pr_activeLock);

        PR_LOG(_pr_thread_lm, PR_LOG_MIN, ("thread exiting"));

        /* All done, time to go away */
        _PR_CleanupThread(thread);

        _PR_NotifyJoinWaiters(thread);

        _PR_DecrActiveThreadCount(thread);

        thread->state = _PR_DEAD_STATE;

        if (!_pr_recycleThreads || (_PR_RecycleThread(thread) ==
                        PR_FAILURE)) {
            /*
             * thread not recycled
             * platform-specific thread exit processing
             *        - for stuff like releasing native-thread resources, etc.