diff options
Diffstat (limited to 'chrome/browser/chrome_thread.h')
| -rw-r--r-- | chrome/browser/chrome_thread.h | 103 |
1 files changed, 74 insertions, 29 deletions
diff --git a/chrome/browser/chrome_thread.h b/chrome/browser/chrome_thread.h index 28e308f..c135d34 100644 --- a/chrome/browser/chrome_thread.h +++ b/chrome/browser/chrome_thread.h @@ -1,11 +1,12 @@ -// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. +// 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. -#ifndef CHROME_BROWSER_CHROME_THREAD_H__ -#define CHROME_BROWSER_CHROME_THREAD_H__ +#ifndef CHROME_BROWSER_CHROME_THREAD_H_ +#define CHROME_BROWSER_CHROME_THREAD_H_ #include "base/lock.h" +#include "base/task.h" #include "base/thread.h" /////////////////////////////////////////////////////////////////////////////// @@ -14,30 +15,29 @@ // This class represents a thread that is known by a browser-wide name. For // example, there is one IO thread for the entire browser process, and various // pieces of code find it useful to retrieve a pointer to the IO thread's -// MessageLoop by name: +// Invoke a task by thread ID: // -// MessageLoop* io_loop = ChromeThread::GetMessageLoop(ChromeThread::IO); +// ChromeThread::PostTask(ChromeThread::IO, FROM_HERE, task); // -// On the UI thread, it is often preferable to obtain a pointer to a well-known -// thread via the g_browser_process object, e.g. g_browser_process->io_thread(); -// -// Code that runs on a thread other than the UI thread must take extra care in -// handling pointers to threads because many of the well-known threads are owned -// by the UI thread and can be deallocated without notice. +// The return value is false if the task couldn't be posted because the target +// thread doesn't exist. If this could lead to data loss, you need to check the +// result and restructure the code to ensure it doesn't occur. // +// This class automatically handles the lifetime of different threads. +// It's always safe to call PostTask on any thread. If it's not yet created, +// the task is deleted. There are no race conditions. If the thread that the +// task is posted to is guaranteed to outlive the current thread, then no locks +// are used. You should never need to cache pointers to MessageLoops, since +// they're not thread safe. class ChromeThread : public base::Thread { public: // An enumeration of the well-known threads. + // NOTE: threads must be listed in the order of their life-time, with each + // thread outliving every other thread below it. enum ID { // The main thread in the browser. UI, - // This is the thread that processes IPC and network messages. - IO, - - // This is the thread that interacts with the file system. - FILE, - // This is the thread that interacts with the database. DB, @@ -45,6 +45,12 @@ class ChromeThread : public base::Thread { // NOT in --single-process mode. WEBKIT, + // This is the thread that interacts with the file system. + FILE, + + // This is the thread that processes IPC and network messages. + IO, + #if defined(OS_LINUX) // This thread has a second connection to the X server and is used to // process UI requests when routing the request to the UI thread would risk @@ -62,20 +68,48 @@ class ChromeThread : public base::Thread { // to construct a ChromeThread that already exists. explicit ChromeThread(ID identifier); - // Special constructor for the main (UI) thread. We use a dummy thread here - // since the main thread already exists. - ChromeThread(); + // Special constructor for the main (UI) thread and unittests. We use a dummy + // thread here since the main thread already exists. + ChromeThread(ID identifier, MessageLoop* message_loop); virtual ~ChromeThread(); - // Callable on any thread, this helper function returns a pointer to the - // thread's MessageLoop. - // - // WARNING: - // Nothing in this class prevents the MessageLoop object returned from this - // function from being destroyed on another thread. Use with care. - // - static MessageLoop* GetMessageLoop(ID identifier); + // These are the same methods in message_loop.h, but are guaranteed to either + // get posted to the MessageLoop if it's still alive, or be deleted otherwise. + // They return true iff the thread existed and the task was posted. Note that + // even if the task is posted, there's no guarantee that it will run, since + // the target thread may already have a Quit message in its queue. + static bool PostTask(ID identifier, + const tracked_objects::Location& from_here, + Task* task); + static bool PostDelayedTask(ID identifier, + const tracked_objects::Location& from_here, + Task* task, + int64 delay_ms); + static bool PostNonNestableTask(ID identifier, + const tracked_objects::Location& from_here, + Task* task); + static bool PostNonNestableDelayedTask( + ID identifier, + const tracked_objects::Location& from_here, + Task* task, + int64 delay_ms); + + template <class T> + static bool DeleteSoon(ID identifier, + const tracked_objects::Location& from_here, + T* object) { + return PostNonNestableTask( + identifier, from_here, new DeleteTask<T>(object)); + } + + template <class T> + static bool ReleaseSoon(ID identifier, + const tracked_objects::Location& from_here, + T* object) { + return PostNonNestableTask( + identifier, from_here, new ReleaseTask<T>(object)); + } // Callable on any thread. Returns whether you're currently on a particular // thread. @@ -91,6 +125,17 @@ class ChromeThread : public base::Thread { // Common initialization code for the constructors. void Initialize(); + // If the current message loop is one of the known threads, returns true and + // sets identifier to its ID. Otherwise returns false. + static bool GetCurrentThreadIdentifier(ID* identifier); + + static bool PostTaskHelper( + ID identifier, + const tracked_objects::Location& from_here, + Task* task, + int64 delay_ms, + bool nestable); + // The identifier of this thread. Only one thread can exist with a given // identifier at a given time. ID identifier_; @@ -106,4 +151,4 @@ class ChromeThread : public base::Thread { static ChromeThread* chrome_threads_[ID_COUNT]; }; -#endif // #ifndef CHROME_BROWSER_CHROME_THREAD_H__ +#endif // #ifndef CHROME_BROWSER_CHROME_THREAD_H_ |