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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/chrome_thread.h"
// Friendly names for the well-known threads.
static const char* chrome_thread_names[ChromeThread::ID_COUNT] = {
"", // UI (name assembled in browser_main.cc).
"Chrome_DBThread", // DB
"Chrome_WebKitThread", // WEBKIT
"Chrome_FileThread", // FILE
"Chrome_ProcessLauncherThread", // PROCESS_LAUNCHER
"Chrome_IOThread", // IO
#if defined(OS_LINUX)
"Chrome_Background_X11Thread", // BACKGROUND_X11
#endif
};
Lock ChromeThread::lock_;
ChromeThread* ChromeThread::chrome_threads_[ID_COUNT];
ChromeThread::ChromeThread(ChromeThread::ID identifier)
: Thread(chrome_thread_names[identifier]),
identifier_(identifier) {
Initialize();
}
ChromeThread::ChromeThread(ID identifier, MessageLoop* message_loop)
: Thread(message_loop->thread_name().c_str()),
identifier_(identifier) {
set_message_loop(message_loop);
Initialize();
}
void ChromeThread::Initialize() {
AutoLock lock(lock_);
DCHECK(identifier_ >= 0 && identifier_ < ID_COUNT);
DCHECK(chrome_threads_[identifier_] == NULL);
chrome_threads_[identifier_] = this;
}
ChromeThread::~ChromeThread() {
// Stop the thread here, instead of the parent's class destructor. This is so
// that if there are pending tasks that run, code that checks that it's on the
// correct ChromeThread succeeds.
Stop();
AutoLock lock(lock_);
chrome_threads_[identifier_] = NULL;
#ifndef NDEBUG
// Double check that the threads are ordererd correctly in the enumeration.
for (int i = identifier_ + 1; i < ID_COUNT; ++i) {
DCHECK(!chrome_threads_[i]) <<
"Threads must be listed in the reverse order that they die";
}
#endif
}
// static
bool ChromeThread::IsWellKnownThread(ID identifier) {
AutoLock lock(lock_);
return (identifier >= 0 && identifier < ID_COUNT &&
chrome_threads_[identifier]);
}
// static
bool ChromeThread::CurrentlyOn(ID identifier) {
AutoLock lock(lock_);
DCHECK(identifier >= 0 && identifier < ID_COUNT);
return chrome_threads_[identifier] &&
chrome_threads_[identifier]->message_loop() == MessageLoop::current();
}
// static
bool ChromeThread::PostTask(ID identifier,
const tracked_objects::Location& from_here,
Task* task) {
return PostTaskHelper(identifier, from_here, task, 0, true);
}
// static
bool ChromeThread::PostDelayedTask(ID identifier,
const tracked_objects::Location& from_here,
Task* task,
int64 delay_ms) {
return PostTaskHelper(identifier, from_here, task, delay_ms, true);
}
// static
bool ChromeThread::PostNonNestableTask(
ID identifier,
const tracked_objects::Location& from_here,
Task* task) {
return PostTaskHelper(identifier, from_here, task, 0, false);
}
// static
bool ChromeThread::PostNonNestableDelayedTask(
ID identifier,
const tracked_objects::Location& from_here,
Task* task,
int64 delay_ms) {
return PostTaskHelper(identifier, from_here, task, delay_ms, false);
}
// static
bool ChromeThread::GetCurrentThreadIdentifier(ID* identifier) {
MessageLoop* cur_message_loop = MessageLoop::current();
for (int i = 0; i < ID_COUNT; ++i) {
if (chrome_threads_[i] &&
chrome_threads_[i]->message_loop() == cur_message_loop) {
*identifier = chrome_threads_[i]->identifier_;
return true;
}
}
return false;
}
// static
bool ChromeThread::PostTaskHelper(
ID identifier,
const tracked_objects::Location& from_here,
Task* task,
int64 delay_ms,
bool nestable) {
DCHECK(identifier >= 0 && identifier < ID_COUNT);
// Optimization: to avoid unnecessary locks, we listed the ID enumeration in
// order of lifetime. So no need to lock if we know that the other thread
// outlives this one.
// Note: since the array is so small, ok to loop instead of creating a map,
// which would require a lock because std::map isn't thread safe, defeating
// the whole purpose of this optimization.
ID current_thread;
bool guaranteed_to_outlive_target_thread =
GetCurrentThreadIdentifier(¤t_thread) &&
current_thread >= identifier;
if (!guaranteed_to_outlive_target_thread)
lock_.Acquire();
MessageLoop* message_loop = chrome_threads_[identifier] ?
chrome_threads_[identifier]->message_loop() : NULL;
if (message_loop) {
if (nestable) {
message_loop->PostDelayedTask(from_here, task, delay_ms);
} else {
message_loop->PostNonNestableDelayedTask(from_here, task, delay_ms);
}
} else {
delete task;
}
if (!guaranteed_to_outlive_target_thread)
lock_.Release();
return !!message_loop;
}
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