michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim:set ts=2 sw=2 sts=2 et cindent: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsEventQueue.h"
michael@0: #include "nsAutoPtr.h"
michael@0: #include "prlog.h"
michael@0: #include "nsThreadUtils.h"
michael@0: #include "prthread.h"
michael@0: #include "mozilla/ChaosMode.h"
michael@0: 
michael@0: using namespace mozilla;
michael@0: 
michael@0: #ifdef PR_LOGGING
michael@0: static PRLogModuleInfo *
michael@0: GetLog()
michael@0: {
michael@0:   static PRLogModuleInfo *sLog;
michael@0:   if (!sLog)
michael@0:     sLog = PR_NewLogModule("nsEventQueue");
michael@0:   return sLog;
michael@0: }
michael@0: #endif
michael@0: #ifdef LOG
michael@0: #undef LOG
michael@0: #endif
michael@0: #define LOG(args) PR_LOG(GetLog(), PR_LOG_DEBUG, args)
michael@0: 
michael@0: nsEventQueue::nsEventQueue()
michael@0:   : mReentrantMonitor("nsEventQueue.mReentrantMonitor")
michael@0:   , mHead(nullptr)
michael@0:   , mTail(nullptr)
michael@0:   , mOffsetHead(0)
michael@0:   , mOffsetTail(0)
michael@0: {
michael@0: }
michael@0: 
michael@0: nsEventQueue::~nsEventQueue()
michael@0: {
michael@0:   // It'd be nice to be able to assert that no one else is holding the monitor,
michael@0:   // but NSPR doesn't really expose APIs for it.
michael@0:   NS_ASSERTION(IsEmpty(), "Non-empty event queue being destroyed; events being leaked.");
michael@0: 
michael@0:   if (mHead)
michael@0:     FreePage(mHead);
michael@0: }
michael@0: 
michael@0: bool
michael@0: nsEventQueue::GetEvent(bool mayWait, nsIRunnable **result)
michael@0: {
michael@0:   {
michael@0:     ReentrantMonitorAutoEnter mon(mReentrantMonitor);
michael@0:     
michael@0:     while (IsEmpty()) {
michael@0:       if (!mayWait) {
michael@0:         if (result)
michael@0:           *result = nullptr;
michael@0:         return false;
michael@0:       }
michael@0:       LOG(("EVENTQ(%p): wait begin\n", this)); 
michael@0:       mon.Wait();
michael@0:       LOG(("EVENTQ(%p): wait end\n", this)); 
michael@0:     }
michael@0:     
michael@0:     if (result) {
michael@0:       *result = mHead->mEvents[mOffsetHead++];
michael@0:       
michael@0:       // Check if mHead points to empty Page
michael@0:       if (mOffsetHead == EVENTS_PER_PAGE) {
michael@0:         Page *dead = mHead;
michael@0:         mHead = mHead->mNext;
michael@0:         FreePage(dead);
michael@0:         mOffsetHead = 0;
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool
michael@0: nsEventQueue::PutEvent(nsIRunnable *runnable)
michael@0: {
michael@0:   // Avoid calling AddRef+Release while holding our monitor.
michael@0:   nsRefPtr<nsIRunnable> event(runnable);
michael@0:   bool rv = true;
michael@0:   {
michael@0:     if (ChaosMode::isActive()) {
michael@0:       // With probability 0.5, yield so other threads have a chance to
michael@0:       // dispatch events to this queue first.
michael@0:       if (ChaosMode::randomUint32LessThan(2)) {
michael@0:         PR_Sleep(PR_INTERVAL_NO_WAIT);
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     ReentrantMonitorAutoEnter mon(mReentrantMonitor);
michael@0: 
michael@0:     if (!mHead) {
michael@0:       mHead = NewPage();
michael@0:       if (!mHead) {
michael@0:         rv = false;
michael@0:       } else {
michael@0:         mTail = mHead;
michael@0:         mOffsetHead = 0;
michael@0:         mOffsetTail = 0;
michael@0:       }
michael@0:     } else if (mOffsetTail == EVENTS_PER_PAGE) {
michael@0:       Page *page = NewPage();
michael@0:       if (!page) {
michael@0:         rv = false;
michael@0:       } else {
michael@0:         mTail->mNext = page;
michael@0:         mTail = page;
michael@0:         mOffsetTail = 0;
michael@0:       }
michael@0:     }
michael@0:     if (rv) {
michael@0:       event.swap(mTail->mEvents[mOffsetTail]);
michael@0:       ++mOffsetTail;
michael@0:       LOG(("EVENTQ(%p): notify\n", this)); 
michael@0:       mon.NotifyAll();
michael@0:     }
michael@0:   }
michael@0:   return rv;
michael@0: }