pruthr.c

Netscape NSPR库源码

                goto found_thread;
            }
        }
    }
    _PR_CPU_LIST_UNLOCK();
    if (wakeup_cpus == PR_TRUE)
        _PR_MD_WAKEUP_CPUS();

#endif        /* _PR_LOCAL_THREADS_ONLY */

idle_thread:
   /*
    ** There are no threads to run. Switch to the idle thread
    */
    PR_LOG(_pr_sched_lm, PR_LOG_MAX, ("pausing"));
    thread = _PR_MD_CURRENT_CPU()->idle_thread;

found_thread:
    PR_ASSERT((me == thread) || ((thread->state == _PR_RUNNABLE) &&
                    (!(thread->no_sched))));

    /* Resume the thread */
    PR_LOG(_pr_sched_lm, PR_LOG_MAX,
       ("switching to %d[%p]", thread->id, thread));
    PR_ASSERT(thread->state != _PR_RUNNING);
    thread->state = _PR_RUNNING;
 
    /* If we are on the runq, it just means that we went to sleep on some
     * resource, and by the time we got here another real native thread had
     * already given us the resource and put us back on the runqueue 
     */
	PR_ASSERT(thread->cpu == _PR_MD_CURRENT_CPU());
    if (thread != me) 
        _PR_MD_RESTORE_CONTEXT(thread);
#if 0
    /* XXXMB; with setjmp/longjmp it is impossible to land here, but 
     * it is not with fibers... Is this a bad thing?  I believe it is 
     * still safe.
     */
    PR_NOT_REACHED("impossible return from schedule");
#endif
}

/*
** Attaches a thread.  
** Does not set the _PR_MD_CURRENT_THREAD.  
** Does not specify the scope of the thread.
*/
static PRThread *
_PR_AttachThread(PRThreadType type, PRThreadPriority priority,
    PRThreadStack *stack)
{
#if defined(XP_MAC)
#pragma unused (type)
#endif

    PRThread *thread;
    char *mem;

    if (priority > PR_PRIORITY_LAST) {
        priority = PR_PRIORITY_LAST;
    } else if (priority < PR_PRIORITY_FIRST) {
        priority = PR_PRIORITY_FIRST;
    }

    mem = (char*) PR_CALLOC(sizeof(PRThread));
    if (mem) {
        thread = (PRThread*) mem;
        thread->priority = priority;
        thread->stack = stack;
        thread->state = _PR_RUNNING;
        PR_INIT_CLIST(&thread->lockList);
        if (_PR_MD_NEW_LOCK(&thread->threadLock) == PR_FAILURE) {
        PR_DELETE(thread);
        return 0;
    }

        return thread;
    }
    return 0;
}



PR_IMPLEMENT(PRThread*) 
_PR_NativeCreateThread(PRThreadType type,
                     void (*start)(void *arg),
                     void *arg,
                     PRThreadPriority priority,
                     PRThreadScope scope,
                     PRThreadState state,
                     PRUint32 stackSize,
                     PRUint32 flags)
{
#if defined(XP_MAC)
#pragma unused (scope)
#endif

    PRThread *thread;

    thread = _PR_AttachThread(type, priority, NULL);

    if (thread) {
        PR_Lock(_pr_activeLock);
        thread->flags = (flags | _PR_GLOBAL_SCOPE);
        thread->id = ++_pr_utid;
        if (type == PR_SYSTEM_THREAD) {
            thread->flags |= _PR_SYSTEM;
            _pr_systemActive++;
        } else {
            _pr_userActive++;
        }
        PR_Unlock(_pr_activeLock);

        thread->stack = PR_NEWZAP(PRThreadStack);
        if (!thread->stack) {
            PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
            goto done;
        }
        thread->stack->stackSize = stackSize?stackSize:_MD_DEFAULT_STACK_SIZE;
        thread->stack->thr = thread;
        thread->startFunc = start;
        thread->arg = arg;

        /* 
          Set thread flags related to scope and joinable state. If joinable
          thread, allocate a "termination" conidition variable.
         */
        if (state == PR_JOINABLE_THREAD) {
            thread->term = PR_NewCondVar(_pr_terminationCVLock);
        if (thread->term == NULL) {
        PR_DELETE(thread->stack);
        goto done;
        }
        }

    thread->state = _PR_RUNNING;
        if (_PR_MD_CREATE_THREAD(thread, _PR_NativeRunThread, priority,
            scope,state,stackSize) == PR_SUCCESS) {
            return thread;
        }
        if (thread->term) {
            PR_DestroyCondVar(thread->term);
            thread->term = NULL;
        }
    PR_DELETE(thread->stack);
    }

done:
    if (thread) {
    _PR_DecrActiveThreadCount(thread);
        _PR_DestroyThread(thread);
    }
    return NULL;
}

/************************************************************************/

PR_IMPLEMENT(PRThread*) _PR_CreateThread(PRThreadType type,
                     void (*start)(void *arg),
                     void *arg,
                     PRThreadPriority priority,
                     PRThreadScope scope,
                     PRThreadState state,
                     PRUint32 stackSize,
                     PRUint32 flags)
{
    PRThread *me;
    PRThread *thread = NULL;
    PRThreadStack *stack;
    char *top;
    PRIntn is;
    PRIntn native = 0;
    PRIntn useRecycled = 0;
    PRBool status;

    /* 
    First, pin down the priority.  Not all compilers catch passing out of
    range enum here.  If we let bad values thru, priority queues won't work.
    */
    if (priority > PR_PRIORITY_LAST) {
        priority = PR_PRIORITY_LAST;
    } else if (priority < PR_PRIORITY_FIRST) {
        priority = PR_PRIORITY_FIRST;
    }
        
    if (!_pr_initialized) _PR_ImplicitInitialization();

    if (! (flags & _PR_IDLE_THREAD))
        me = _PR_MD_CURRENT_THREAD();

#if    defined(_PR_GLOBAL_THREADS_ONLY)
	/*
	 * can create global threads only
	 */
    if (scope == PR_LOCAL_THREAD)
    	scope = PR_GLOBAL_THREAD;
#endif

	if (_native_threads_only)
		scope = PR_GLOBAL_THREAD;

    native = (((scope == PR_GLOBAL_THREAD)|| (scope == PR_GLOBAL_BOUND_THREAD))
							&& _PR_IS_NATIVE_THREAD_SUPPORTED());

    _PR_ADJUST_STACKSIZE(stackSize);

    if (native) {
    /*
     * clear the IDLE_THREAD flag which applies to LOCAL
     * threads only
     */
    flags &= ~_PR_IDLE_THREAD;
        flags |= _PR_GLOBAL_SCOPE;
        if (_PR_NUM_DEADNATIVE > 0) {
            _PR_DEADQ_LOCK;

            if (_PR_NUM_DEADNATIVE == 0) { /* Thread safe check */
                _PR_DEADQ_UNLOCK;
            } else {
                thread = _PR_THREAD_PTR(_PR_DEADNATIVEQ.next);
                PR_REMOVE_LINK(&thread->links);
                _PR_DEC_DEADNATIVE;
                _PR_DEADQ_UNLOCK;

                _PR_InitializeRecycledThread(thread);
                thread->startFunc = start;
                thread->arg = arg;
            thread->flags = (flags | _PR_GLOBAL_SCOPE);
            if (type == PR_SYSTEM_THREAD)
            {
                thread->flags |= _PR_SYSTEM;
                PR_AtomicIncrement(&_pr_systemActive);
            }
            else PR_AtomicIncrement(&_pr_userActive);

            if (state == PR_JOINABLE_THREAD) {
                if (!thread->term) 
                       thread->term = PR_NewCondVar(_pr_terminationCVLock);
            }
        else {
                if(thread->term) {
                    PR_DestroyCondVar(thread->term);
                        thread->term = 0;
            }
            }

                thread->priority = priority;
        _PR_MD_SET_PRIORITY(&(thread->md), priority);
        /* XXX what about stackSize? */
        thread->state = _PR_RUNNING;
                _PR_MD_WAKEUP_WAITER(thread);
        return thread;
            }
        }
        thread = _PR_NativeCreateThread(type, start, arg, priority, 
                                            scope, state, stackSize, flags);
    } else {
        if (_PR_NUM_DEADUSER > 0) {
            _PR_DEADQ_LOCK;

            if (_PR_NUM_DEADUSER == 0) {  /* thread safe check */
                _PR_DEADQ_UNLOCK;
            } else {
                PRCList *ptr;

                /* Go down list checking for a recycled thread with a 
                 * large enough stack.  XXXMB - this has a bad degenerate case.
                 */
                ptr = _PR_DEADUSERQ.next;
                while( ptr != &_PR_DEADUSERQ ) {
                    thread = _PR_THREAD_PTR(ptr);
                    if ((thread->stack->stackSize >= stackSize) &&
                (!thread->no_sched)) {
                        PR_REMOVE_LINK(&thread->links);
                        _PR_DEC_DEADUSER;
                        break;
                    } else {
                        ptr = ptr->next;
                        thread = NULL;
                    }
                } 

                _PR_DEADQ_UNLOCK;

               if (thread) {
                    _PR_InitializeRecycledThread(thread);
                    thread->startFunc = start;
                    thread->arg = arg;
                    thread->priority = priority;
            if (state == PR_JOINABLE_THREAD) {
            if (!thread->term) 
               thread->term = PR_NewCondVar(_pr_terminationCVLock);
            } else {
            if(thread->term) {
               PR_DestroyCondVar(thread->term);
                thread->term = 0;
            }
            }
                    useRecycled++;
                }
            }
        } 
        if (thread == NULL) {
#ifndef HAVE_CUSTOM_USER_THREADS
            stack = _PR_NewStack(stackSize);
            if (!stack) {
                PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
                return NULL;
            }

            /* Allocate thread object and per-thread data off the top of the stack*/
            top = stack->stackTop;
#ifdef HAVE_STACK_GROWING_UP
            thread = (PRThread*) top;
            top = top + sizeof(PRThread);
            /*
             * Make stack 64-byte aligned
             */
            if ((PRUptrdiff)top & 0x3f) {
                top = (char*)(((PRUptrdiff)top + 0x40) & ~0x3f);
            }
#else
            top = top - sizeof(PRThread);
            thread = (PRThread*) top;
            /*
             * Make stack 64-byte aligned
             */
            if ((PRUptrdiff)top & 0x3f) {
                top = (char*)((PRUptrdiff)top & ~0x3f);
            }
#endif
#if defined(GC_LEAK_DETECTOR)
            /*
             * sorry, it is not safe to allocate the thread on the stack,
             * because we assign to this object before the GC can learn
             * about this thread. we'll just leak thread objects instead.
             */
            thread = PR_NEW(PRThread);
#endif
            stack->thr = thread;
            memset(thread, 0, sizeof(PRThread));
            thread->threadAllocatedOnStack = 1;
#else
            thread = _PR_MD_CREATE_USER_THREAD(stackSize, start, arg);
            if (!thread) {
                PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
                return NULL;
            }
            thread->threadAllocatedOnStack = 0;
            stack = NULL;
            top = NULL;
#endif

            /* Initialize thread */
            thread->tpdLength = 0;
            thread->privateData = NULL;
            thread->stack = stack;
            thread->priority = priority;
            thread->startFunc = start;
            thread->arg = arg;
            PR_INIT_CLIST(&thread->lockList);

            if (_PR_MD_INIT_THREAD(thread) == PR_FAILURE) {
                if (thread->threadAllocatedOnStack == 1)
                    _PR_FreeStack(thread->stack);
                else {
                    PR_DELETE(thread);
                }
                PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
                return NULL;
            }

            if (_PR_MD_NEW_LOCK(&thread->threadLock) == PR_FAILURE) {
                if (thread->threadAllocatedOnStack == 1)
                    _PR_FreeStack(thread->stack);
                else {
                    PR_DELETE(thread->privateData);
                    PR_DELETE(thread);
                }
                PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, 0);
                return NULL;
            }

            _PR_MD_INIT_CONTEXT(thread, top, _PR_UserRunThread, &status);

            if (status == PR_FALSE) {
                _PR_MD_FREE_LOCK(&thread->threadLock);
                if (thread->threadAllocatedOnStack == 1)
                    _PR_FreeStack(thread->stack);
                else {
                    PR_DELETE(thread->privateData);
                    PR_DELETE(thread);
                }
                return NULL;
            }

            /* 
              Set thread flags related to scope and joinable state. If joinable
              thread, allocate a "termination" condition variable.
            */
            if (state == PR_JOINABLE_THREAD) {
                thread->term = PR_NewCondVar(_pr_terminationCVLock);
                if (thread->term == NULL) {
                    _PR_MD_FREE_LOCK(&thread->threadLock);
                    if (thread->threadAllocatedOnStack == 1)
                        _PR_FreeStack(thread->stack);
                    else {
                        PR_DELETE(thread->privateData);
                        PR_DELETE(thread);
                    }
                    return NULL;
                }
            }
  
        }
  
        /* Update thread type counter */
        PR_Lock(_pr_activeLock);
        thread->flags = flags;
        thread->id = ++_pr_utid;
        if (type == PR_SYSTEM_THREAD) {
            thread->flags |= _PR_SYSTEM;
            _pr_systemActive++;
        } else {
            _pr_userActive++;
        }

        /* Make thread runnable */
        thread->state = _PR_RUNNABLE;
    /*
     * Add to list of active threads
     */
        PR_Unlock(_pr_activeLock);

        if ((! (thread->flags & _PR_IDLE_THREAD)) && _PR_IS_NATIVE_THREAD(me) )
            thread->cpu = _PR_GetPrimordialCPU();
        else
            thread->cpu = _PR_MD_CURRENT_CPU();

        PR_ASSERT(!_PR_IS_NATIVE_THREAD(thread));

        if ((! (thread->flags & _PR_IDLE_THREAD)) && !_PR_IS_NATIVE_THREAD(me)) {
            _PR_INTSOFF(is);
            _PR_RUNQ_LOCK(thread->cpu);
            _PR_ADD_RUNQ(thread, thread->cpu, priority);
            _PR_RUNQ_UNLOCK(thread->cpu);
        }

        if (thread->flags & _PR_IDLE_THREAD) {
            /*
            ** If the creating thread is a kernel thread, we need to
            ** awaken the user thread idle thread somehow; potentially
            ** it could be sleeping in its idle loop, and we need to poke
            ** it.  To do so, wake the idle thread...  
            */
            _PR_MD_WAKEUP_WAITER(NULL);
        } else if (_PR_IS_NATIVE_THREAD(me)) {
            _PR_MD_WAKEUP_WAITER(thread);
        }
        if ((! (thread->flags & _PR_IDLE_THREAD)) && !_PR_IS_NATIVE_THREAD(me) )
            _PR_INTSON(is);
    }

    return thread;
}

PR_IMPLEMENT(PRThread*) PR_CreateThread(PRThreadType type,
                     void (*start)(void *arg),
                     void *arg,
                     PRThreadPriority priority,
                     PRThreadScope scope,
                     PRThreadState state,
                     PRUint32 stackSize)
{
    return _PR_CreateThread(type, start, arg, priority, scope, state,