| /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| /* This Source Code Form is subject to the terms of the Mozilla Public |
| * License, v. 2.0. If a copy of the MPL was not distributed with this |
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| |
| #include "primpl.h" |
| |
| /************************************************************************/ |
| |
| /* |
| * Notifies just get posted to the monitor. The actual notification is done |
| * when the monitor is fully exited so that MP systems don't contend for a |
| * monitor that they can't enter. |
| */ |
| static void _PR_PostNotifyToMonitor(PRMonitor *mon, PRBool broadcast) |
| { |
| PR_ASSERT(mon != NULL); |
| PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mon); |
| |
| /* mon->notifyTimes is protected by the monitor, so we don't need to |
| * acquire mon->lock. |
| */ |
| if (broadcast) |
| mon->notifyTimes = -1; |
| else if (mon->notifyTimes != -1) |
| mon->notifyTimes += 1; |
| } |
| |
| static void _PR_PostNotifiesFromMonitor(PRCondVar *cv, PRIntn times) |
| { |
| PRStatus rv; |
| |
| /* |
| * Time to actually notify any waits that were affected while the monitor |
| * was entered. |
| */ |
| PR_ASSERT(cv != NULL); |
| PR_ASSERT(times != 0); |
| if (times == -1) { |
| rv = PR_NotifyAllCondVar(cv); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } else { |
| while (times-- > 0) { |
| rv = PR_NotifyCondVar(cv); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } |
| } |
| } |
| |
| /* |
| ** Create a new monitor. |
| */ |
| PR_IMPLEMENT(PRMonitor*) PR_NewMonitor() |
| { |
| PRMonitor *mon; |
| PRStatus rv; |
| |
| if (!_pr_initialized) _PR_ImplicitInitialization(); |
| |
| mon = PR_NEWZAP(PRMonitor); |
| if (mon == NULL) { |
| PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0); |
| return NULL; |
| } |
| |
| rv = _PR_InitLock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| if (rv != PR_SUCCESS) |
| goto error1; |
| |
| mon->owner = NULL; |
| |
| rv = _PR_InitCondVar(&mon->entryCV, &mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| if (rv != PR_SUCCESS) |
| goto error2; |
| |
| rv = _PR_InitCondVar(&mon->waitCV, &mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| if (rv != PR_SUCCESS) |
| goto error3; |
| |
| mon->notifyTimes = 0; |
| mon->entryCount = 0; |
| mon->name = NULL; |
| return mon; |
| |
| error3: |
| _PR_FreeCondVar(&mon->entryCV); |
| error2: |
| _PR_FreeLock(&mon->lock); |
| error1: |
| PR_Free(mon); |
| return NULL; |
| } |
| |
| PR_IMPLEMENT(PRMonitor*) PR_NewNamedMonitor(const char* name) |
| { |
| PRMonitor* mon = PR_NewMonitor(); |
| if (mon) |
| mon->name = name; |
| return mon; |
| } |
| |
| /* |
| ** Destroy a monitor. There must be no thread waiting on the monitor's |
| ** condition variable. The caller is responsible for guaranteeing that the |
| ** monitor is no longer in use. |
| */ |
| PR_IMPLEMENT(void) PR_DestroyMonitor(PRMonitor *mon) |
| { |
| PR_ASSERT(mon != NULL); |
| _PR_FreeCondVar(&mon->waitCV); |
| _PR_FreeCondVar(&mon->entryCV); |
| _PR_FreeLock(&mon->lock); |
| #if defined(DEBUG) |
| memset(mon, 0xaf, sizeof(PRMonitor)); |
| #endif |
| PR_Free(mon); |
| } |
| |
| /* |
| ** Enter the lock associated with the monitor. |
| */ |
| PR_IMPLEMENT(void) PR_EnterMonitor(PRMonitor *mon) |
| { |
| PRThread *me = _PR_MD_CURRENT_THREAD(); |
| PRStatus rv; |
| |
| PR_ASSERT(mon != NULL); |
| PR_Lock(&mon->lock); |
| if (mon->entryCount != 0) { |
| if (mon->owner == me) |
| goto done; |
| while (mon->entryCount != 0) { |
| rv = PR_WaitCondVar(&mon->entryCV, PR_INTERVAL_NO_TIMEOUT); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } |
| } |
| /* and now I have the monitor */ |
| PR_ASSERT(mon->notifyTimes == 0); |
| PR_ASSERT(mon->owner == NULL); |
| mon->owner = me; |
| |
| done: |
| mon->entryCount += 1; |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } |
| |
| /* |
| ** Test and then enter the lock associated with the monitor if it's not |
| ** already entered by some other thread. Return PR_FALSE if some other |
| ** thread owned the lock at the time of the call. |
| */ |
| PR_IMPLEMENT(PRBool) PR_TestAndEnterMonitor(PRMonitor *mon) |
| { |
| PRThread *me = _PR_MD_CURRENT_THREAD(); |
| PRStatus rv; |
| |
| PR_ASSERT(mon != NULL); |
| PR_Lock(&mon->lock); |
| if (mon->entryCount != 0) { |
| if (mon->owner == me) |
| goto done; |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return PR_FALSE; |
| } |
| /* and now I have the monitor */ |
| PR_ASSERT(mon->notifyTimes == 0); |
| PR_ASSERT(mon->owner == NULL); |
| mon->owner = me; |
| |
| done: |
| mon->entryCount += 1; |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return PR_TRUE; |
| } |
| |
| /* |
| ** Exit the lock associated with the monitor once. |
| */ |
| PR_IMPLEMENT(PRStatus) PR_ExitMonitor(PRMonitor *mon) |
| { |
| PRThread *me = _PR_MD_CURRENT_THREAD(); |
| PRStatus rv; |
| |
| PR_ASSERT(mon != NULL); |
| PR_Lock(&mon->lock); |
| /* the entries should be > 0 and we'd better be the owner */ |
| PR_ASSERT(mon->entryCount > 0); |
| PR_ASSERT(mon->owner == me); |
| if (mon->entryCount == 0 || mon->owner != me) |
| { |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return PR_FAILURE; |
| } |
| |
| mon->entryCount -= 1; /* reduce by one */ |
| if (mon->entryCount == 0) |
| { |
| /* and if it transitioned to zero - notify an entry waiter */ |
| /* make the owner unknown */ |
| mon->owner = NULL; |
| if (mon->notifyTimes != 0) { |
| _PR_PostNotifiesFromMonitor(&mon->waitCV, mon->notifyTimes); |
| mon->notifyTimes = 0; |
| } |
| rv = PR_NotifyCondVar(&mon->entryCV); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return PR_SUCCESS; |
| } |
| |
| /* |
| ** Return the number of times that the current thread has entered the |
| ** lock. Returns zero if the current thread has not entered the lock. |
| */ |
| PR_IMPLEMENT(PRIntn) PR_GetMonitorEntryCount(PRMonitor *mon) |
| { |
| PRThread *me = _PR_MD_CURRENT_THREAD(); |
| PRStatus rv; |
| PRIntn count = 0; |
| |
| PR_Lock(&mon->lock); |
| if (mon->owner == me) |
| count = mon->entryCount; |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return count; |
| } |
| |
| PR_IMPLEMENT(void) PR_AssertCurrentThreadInMonitor(PRMonitor *mon) |
| { |
| #if defined(DEBUG) || defined(FORCE_PR_ASSERT) |
| PRStatus rv; |
| |
| PR_Lock(&mon->lock); |
| PR_ASSERT(mon->entryCount != 0 && |
| mon->owner == _PR_MD_CURRENT_THREAD()); |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| #endif |
| } |
| |
| /* |
| ** Wait for a notify on the condition variable. Sleep for "ticks" amount |
| ** of time (if "tick" is 0 then the sleep is indefinite). While |
| ** the thread is waiting it exits the monitors lock (as if it called |
| ** PR_ExitMonitor as many times as it had called PR_EnterMonitor). When |
| ** the wait has finished the thread regains control of the monitors lock |
| ** with the same entry count as before the wait began. |
| ** |
| ** The thread waiting on the monitor will be resumed when the monitor is |
| ** notified (assuming the thread is the next in line to receive the |
| ** notify) or when the "ticks" elapses. |
| ** |
| ** Returns PR_FAILURE if the caller has not locked the lock associated |
| ** with the condition variable. |
| ** This routine can return PR_PENDING_INTERRUPT_ERROR if the waiting thread |
| ** has been interrupted. |
| */ |
| PR_IMPLEMENT(PRStatus) PR_Wait(PRMonitor *mon, PRIntervalTime ticks) |
| { |
| PRStatus rv; |
| PRUint32 saved_entries; |
| PRThread *saved_owner; |
| |
| PR_ASSERT(mon != NULL); |
| PR_Lock(&mon->lock); |
| /* the entries better be positive */ |
| PR_ASSERT(mon->entryCount > 0); |
| /* and it better be owned by us */ |
| PR_ASSERT(mon->owner == _PR_MD_CURRENT_THREAD()); /* XXX return failure */ |
| |
| /* tuck these away 'till later */ |
| saved_entries = mon->entryCount; |
| mon->entryCount = 0; |
| saved_owner = mon->owner; |
| mon->owner = NULL; |
| /* If we have pending notifies, post them now. */ |
| if (mon->notifyTimes != 0) { |
| _PR_PostNotifiesFromMonitor(&mon->waitCV, mon->notifyTimes); |
| mon->notifyTimes = 0; |
| } |
| rv = PR_NotifyCondVar(&mon->entryCV); |
| PR_ASSERT(rv == PR_SUCCESS); |
| |
| rv = PR_WaitCondVar(&mon->waitCV, ticks); |
| PR_ASSERT(rv == PR_SUCCESS); |
| |
| while (mon->entryCount != 0) { |
| rv = PR_WaitCondVar(&mon->entryCV, PR_INTERVAL_NO_TIMEOUT); |
| PR_ASSERT(rv == PR_SUCCESS); |
| } |
| PR_ASSERT(mon->notifyTimes == 0); |
| /* reinstate the interesting information */ |
| mon->entryCount = saved_entries; |
| mon->owner = saved_owner; |
| |
| rv = PR_Unlock(&mon->lock); |
| PR_ASSERT(rv == PR_SUCCESS); |
| return rv; |
| } |
| |
| /* |
| ** Notify the highest priority thread waiting on the condition |
| ** variable. If a thread is waiting on the condition variable (using |
| ** PR_Wait) then it is awakened and begins waiting on the monitor's lock. |
| */ |
| PR_IMPLEMENT(PRStatus) PR_Notify(PRMonitor *mon) |
| { |
| _PR_PostNotifyToMonitor(mon, PR_FALSE); |
| return PR_SUCCESS; |
| } |
| |
| /* |
| ** Notify all of the threads waiting on the condition variable. All of |
| ** threads are notified in turn. The highest priority thread will |
| ** probably acquire the monitor first when the monitor is exited. |
| */ |
| PR_IMPLEMENT(PRStatus) PR_NotifyAll(PRMonitor *mon) |
| { |
| _PR_PostNotifyToMonitor(mon, PR_TRUE); |
| return PR_SUCCESS; |
| } |
| |
| /************************************************************************/ |
| |
| PRUint32 _PR_MonitorToString(PRMonitor *mon, char *buf, PRUint32 buflen) |
| { |
| PRUint32 nb; |
| |
| if (mon->owner) { |
| nb = PR_snprintf(buf, buflen, "[%p] owner=%d[%p] count=%ld", |
| mon, mon->owner->id, mon->owner, mon->entryCount); |
| } else { |
| nb = PR_snprintf(buf, buflen, "[%p]", mon); |
| } |
| return nb; |
| } |