gecko/xpcom/threads/nsEventQueue.cpp

124 lines
2.7 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsEventQueue.h"
#include "nsAutoPtr.h"
#include "prlog.h"
#include "nsThreadUtils.h"
#include "prthread.h"
#include "mozilla/ChaosMode.h"
using namespace mozilla;
#ifdef PR_LOGGING
static PRLogModuleInfo*
GetLog()
{
static PRLogModuleInfo* sLog;
if (!sLog) {
sLog = PR_NewLogModule("nsEventQueue");
}
return sLog;
}
#endif
#ifdef LOG
#undef LOG
#endif
#define LOG(args) PR_LOG(GetLog(), PR_LOG_DEBUG, args)
nsEventQueue::nsEventQueue()
: mReentrantMonitor("nsEventQueue.mReentrantMonitor")
, mHead(nullptr)
, mTail(nullptr)
, mOffsetHead(0)
, mOffsetTail(0)
{
}
nsEventQueue::~nsEventQueue()
{
// It'd be nice to be able to assert that no one else is holding the monitor,
// but NSPR doesn't really expose APIs for it.
NS_ASSERTION(IsEmpty(),
"Non-empty event queue being destroyed; events being leaked.");
if (mHead) {
FreePage(mHead);
}
}
bool
nsEventQueue::GetEvent(bool aMayWait, nsIRunnable** aResult)
{
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
while (IsEmpty()) {
if (!aMayWait) {
if (aResult) {
*aResult = nullptr;
}
return false;
}
LOG(("EVENTQ(%p): wait begin\n", this));
mon.Wait();
LOG(("EVENTQ(%p): wait end\n", this));
}
if (aResult) {
*aResult = mHead->mEvents[mOffsetHead++];
// Check if mHead points to empty Page
if (mOffsetHead == EVENTS_PER_PAGE) {
Page* dead = mHead;
mHead = mHead->mNext;
FreePage(dead);
mOffsetHead = 0;
}
}
}
return true;
}
void
nsEventQueue::PutEvent(nsIRunnable* aRunnable)
{
// Avoid calling AddRef+Release while holding our monitor.
nsRefPtr<nsIRunnable> event(aRunnable);
if (ChaosMode::isActive()) {
// With probability 0.5, yield so other threads have a chance to
// dispatch events to this queue first.
if (ChaosMode::randomUint32LessThan(2)) {
PR_Sleep(PR_INTERVAL_NO_WAIT);
}
}
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
if (!mHead) {
mHead = NewPage();
MOZ_ASSERT(mHead);
mTail = mHead;
mOffsetHead = 0;
mOffsetTail = 0;
} else if (mOffsetTail == EVENTS_PER_PAGE) {
Page* page = NewPage();
MOZ_ASSERT(page);
mTail->mNext = page;
mTail = page;
mOffsetTail = 0;
}
event.swap(mTail->mEvents[mOffsetTail]);
++mOffsetTail;
LOG(("EVENTQ(%p): notify\n", this));
mon.NotifyAll();
}