1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/threads/nsEventQueue.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,127 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim:set ts=2 sw=2 sts=2 et cindent: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "nsEventQueue.h"
1.11 +#include "nsAutoPtr.h"
1.12 +#include "prlog.h"
1.13 +#include "nsThreadUtils.h"
1.14 +#include "prthread.h"
1.15 +#include "mozilla/ChaosMode.h"
1.16 +
1.17 +using namespace mozilla;
1.18 +
1.19 +#ifdef PR_LOGGING
1.20 +static PRLogModuleInfo *
1.21 +GetLog()
1.22 +{
1.23 + static PRLogModuleInfo *sLog;
1.24 + if (!sLog)
1.25 + sLog = PR_NewLogModule("nsEventQueue");
1.26 + return sLog;
1.27 +}
1.28 +#endif
1.29 +#ifdef LOG
1.30 +#undef LOG
1.31 +#endif
1.32 +#define LOG(args) PR_LOG(GetLog(), PR_LOG_DEBUG, args)
1.33 +
1.34 +nsEventQueue::nsEventQueue()
1.35 + : mReentrantMonitor("nsEventQueue.mReentrantMonitor")
1.36 + , mHead(nullptr)
1.37 + , mTail(nullptr)
1.38 + , mOffsetHead(0)
1.39 + , mOffsetTail(0)
1.40 +{
1.41 +}
1.42 +
1.43 +nsEventQueue::~nsEventQueue()
1.44 +{
1.45 + // It'd be nice to be able to assert that no one else is holding the monitor,
1.46 + // but NSPR doesn't really expose APIs for it.
1.47 + NS_ASSERTION(IsEmpty(), "Non-empty event queue being destroyed; events being leaked.");
1.48 +
1.49 + if (mHead)
1.50 + FreePage(mHead);
1.51 +}
1.52 +
1.53 +bool
1.54 +nsEventQueue::GetEvent(bool mayWait, nsIRunnable **result)
1.55 +{
1.56 + {
1.57 + ReentrantMonitorAutoEnter mon(mReentrantMonitor);
1.58 +
1.59 + while (IsEmpty()) {
1.60 + if (!mayWait) {
1.61 + if (result)
1.62 + *result = nullptr;
1.63 + return false;
1.64 + }
1.65 + LOG(("EVENTQ(%p): wait begin\n", this));
1.66 + mon.Wait();
1.67 + LOG(("EVENTQ(%p): wait end\n", this));
1.68 + }
1.69 +
1.70 + if (result) {
1.71 + *result = mHead->mEvents[mOffsetHead++];
1.72 +
1.73 + // Check if mHead points to empty Page
1.74 + if (mOffsetHead == EVENTS_PER_PAGE) {
1.75 + Page *dead = mHead;
1.76 + mHead = mHead->mNext;
1.77 + FreePage(dead);
1.78 + mOffsetHead = 0;
1.79 + }
1.80 + }
1.81 + }
1.82 +
1.83 + return true;
1.84 +}
1.85 +
1.86 +bool
1.87 +nsEventQueue::PutEvent(nsIRunnable *runnable)
1.88 +{
1.89 + // Avoid calling AddRef+Release while holding our monitor.
1.90 + nsRefPtr<nsIRunnable> event(runnable);
1.91 + bool rv = true;
1.92 + {
1.93 + if (ChaosMode::isActive()) {
1.94 + // With probability 0.5, yield so other threads have a chance to
1.95 + // dispatch events to this queue first.
1.96 + if (ChaosMode::randomUint32LessThan(2)) {
1.97 + PR_Sleep(PR_INTERVAL_NO_WAIT);
1.98 + }
1.99 + }
1.100 +
1.101 + ReentrantMonitorAutoEnter mon(mReentrantMonitor);
1.102 +
1.103 + if (!mHead) {
1.104 + mHead = NewPage();
1.105 + if (!mHead) {
1.106 + rv = false;
1.107 + } else {
1.108 + mTail = mHead;
1.109 + mOffsetHead = 0;
1.110 + mOffsetTail = 0;
1.111 + }
1.112 + } else if (mOffsetTail == EVENTS_PER_PAGE) {
1.113 + Page *page = NewPage();
1.114 + if (!page) {
1.115 + rv = false;
1.116 + } else {
1.117 + mTail->mNext = page;
1.118 + mTail = page;
1.119 + mOffsetTail = 0;
1.120 + }
1.121 + }
1.122 + if (rv) {
1.123 + event.swap(mTail->mEvents[mOffsetTail]);
1.124 + ++mOffsetTail;
1.125 + LOG(("EVENTQ(%p): notify\n", this));
1.126 + mon.NotifyAll();
1.127 + }
1.128 + }
1.129 + return rv;
1.130 +}
