gecko-dev/xpcom/threads/nsEventQueue.cpp

115 lines
2.6 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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"
using namespace mozilla;
#ifdef PR_LOGGING
static PRLogModuleInfo *
GetLog()
{
static PRLogModuleInfo *sLog;
if (!sLog)
sLog = PR_NewLogModule("nsEventQueue");
return sLog;
}
#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 mayWait, nsIRunnable **result)
{
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
while (IsEmpty()) {
if (!mayWait) {
if (result)
*result = nullptr;
return false;
}
LOG(("EVENTQ(%p): wait begin\n", this));
mon.Wait();
LOG(("EVENTQ(%p): wait end\n", this));
}
if (result) {
*result = 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;
}
bool
nsEventQueue::PutEvent(nsIRunnable *runnable)
{
// Avoid calling AddRef+Release while holding our monitor.
nsRefPtr<nsIRunnable> event(runnable);
bool rv = true;
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
if (!mHead) {
mHead = NewPage();
if (!mHead) {
rv = false;
} else {
mTail = mHead;
mOffsetHead = 0;
mOffsetTail = 0;
}
} else if (mOffsetTail == EVENTS_PER_PAGE) {
Page *page = NewPage();
if (!page) {
rv = false;
} else {
mTail->mNext = page;
mTail = page;
mOffsetTail = 0;
}
}
if (rv) {
event.swap(mTail->mEvents[mOffsetTail]);
++mOffsetTail;
LOG(("EVENTQ(%p): notify\n", this));
mon.NotifyAll();
}
}
return rv;
}