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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ | 5 #ifndef CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ |
6 #define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ | 6 #define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ |
7 #pragma once | 7 #pragma once |
8 | 8 |
9 #include "base/basictypes.h" | |
10 #include "base/callback.h" | 9 #include "base/callback.h" |
| 10 #include "base/synchronization/lock.h" |
11 #include "base/task.h" | 11 #include "base/task.h" |
12 #include "base/tracked_objects.h" | 12 #include "base/threading/thread.h" |
13 #include "content/common/content_export.h" | 13 #include "content/common/content_export.h" |
14 #include "content/public/browser/browser_thread_delegate.h" | |
15 | |
16 // TODO(joi): Remove these in a follow-up change and IWYU in files | |
17 // that were getting them directly or indirectly from here. | |
18 #include "base/memory/ref_counted.h" | |
19 #include "base/memory/scoped_ptr.h" | |
20 #include "base/message_loop.h" | |
21 #include "base/message_loop_proxy.h" | |
22 #include "base/synchronization/lock.h" | |
23 #include "base/threading/thread.h" | |
24 | 14 |
25 #if defined(UNIT_TEST) | 15 #if defined(UNIT_TEST) |
26 #include "base/logging.h" | 16 #include "base/logging.h" |
27 #endif // UNIT_TEST | 17 #endif // UNIT_TEST |
28 | 18 |
29 namespace base { | 19 namespace base { |
30 class MessageLoopProxy; | 20 class MessageLoopProxy; |
31 class Thread; | |
32 } | 21 } |
33 | 22 |
34 namespace content { | 23 namespace content { |
35 | 24 |
36 class BrowserThreadImpl; | 25 class BrowserThreadImpl; |
| 26 class DeprecatedBrowserThread; |
37 | 27 |
38 /////////////////////////////////////////////////////////////////////////////// | 28 /////////////////////////////////////////////////////////////////////////////// |
39 // BrowserThread | 29 // BrowserThread |
40 // | 30 // |
41 // Utility functions for threads that are known by a browser-wide | 31 // Utility functions for threads that are known by a browser-wide |
42 // name. For example, there is one IO thread for the entire browser | 32 // name. For example, there is one IO thread for the entire browser |
43 // process, and various pieces of code find it useful to retrieve a | 33 // process, and various pieces of code find it useful to retrieve a |
44 // pointer to the IO thread's message loop. | 34 // pointer to the IO thread's message loop. |
45 // | 35 // |
46 // Invoke a task by thread ID: | 36 // Invoke a task by thread ID: |
47 // | 37 // |
48 // BrowserThread::PostTask(BrowserThread::IO, FROM_HERE, task); | 38 // BrowserThread::PostTask(BrowserThread::IO, FROM_HERE, task); |
49 // | 39 // |
50 // The return value is false if the task couldn't be posted because the target | 40 // The return value is false if the task couldn't be posted because the target |
51 // thread doesn't exist. If this could lead to data loss, you need to check the | 41 // thread doesn't exist. If this could lead to data loss, you need to check the |
52 // result and restructure the code to ensure it doesn't occur. | 42 // result and restructure the code to ensure it doesn't occur. |
53 // | 43 // |
54 // This class automatically handles the lifetime of different threads. | 44 // This class automatically handles the lifetime of different threads. |
55 // It's always safe to call PostTask on any thread. If it's not yet created, | 45 // It's always safe to call PostTask on any thread. If it's not yet created, |
56 // the task is deleted. There are no race conditions. If the thread that the | 46 // the task is deleted. There are no race conditions. If the thread that the |
57 // task is posted to is guaranteed to outlive the current thread, then no locks | 47 // task is posted to is guaranteed to outlive the current thread, then no locks |
58 // are used. You should never need to cache pointers to MessageLoops, since | 48 // are used. You should never need to cache pointers to MessageLoops, since |
59 // they're not thread safe. | 49 // they're not thread safe. |
60 class CONTENT_EXPORT BrowserThread { | 50 class CONTENT_EXPORT BrowserThread : public base::Thread { |
61 public: | 51 public: |
62 // An enumeration of the well-known threads. | 52 // An enumeration of the well-known threads. |
63 // NOTE: threads must be listed in the order of their life-time, with each | 53 // NOTE: threads must be listed in the order of their life-time, with each |
64 // thread outliving every other thread below it. | 54 // thread outliving every other thread below it. |
65 enum ID { | 55 enum ID { |
66 // The main thread in the browser. | 56 // The main thread in the browser. |
67 UI, | 57 UI, |
68 | 58 |
69 // This is the thread that interacts with the database. | 59 // This is the thread that interacts with the database. |
70 DB, | 60 DB, |
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173 | 163 |
174 // If the current message loop is one of the known threads, returns true and | 164 // If the current message loop is one of the known threads, returns true and |
175 // sets identifier to its ID. Otherwise returns false. | 165 // sets identifier to its ID. Otherwise returns false. |
176 static bool GetCurrentThreadIdentifier(ID* identifier); | 166 static bool GetCurrentThreadIdentifier(ID* identifier); |
177 | 167 |
178 // Callers can hold on to a refcounted MessageLoopProxy beyond the lifetime | 168 // Callers can hold on to a refcounted MessageLoopProxy beyond the lifetime |
179 // of the thread. | 169 // of the thread. |
180 static scoped_refptr<base::MessageLoopProxy> GetMessageLoopProxyForThread( | 170 static scoped_refptr<base::MessageLoopProxy> GetMessageLoopProxyForThread( |
181 ID identifier); | 171 ID identifier); |
182 | 172 |
183 // Gets the Thread object for the specified thread, or NULL if the | |
184 // thread has not been created (or has been destroyed during | |
185 // shutdown). | |
186 // | |
187 // Before calling this, you must have called content::ContentMain | |
188 // with a command-line that would specify a browser process (e.g. an | |
189 // empty command line). | |
190 // | |
191 // This is unsafe as your pointer may become invalid close to | |
192 // shutdown. | |
193 // | |
194 // TODO(joi): Remove this once clients such as BrowserProcessImpl | |
195 // (and classes that call things like | |
196 // g_browser_process->file_thread()) are switched to using | |
197 // MessageLoopProxy. | |
198 static base::Thread* UnsafeGetBrowserThread(ID identifier); | |
199 | |
200 // Sets the delegate for the specified BrowserThread. | |
201 // | |
202 // Only one delegate may be registered at a time. Delegates may be | |
203 // unregistered by providing a NULL pointer. | |
204 // | |
205 // If the caller unregisters a delegate before CleanUp has been | |
206 // called, it must perform its own locking to ensure the delegate is | |
207 // not deleted while unregistering. | |
208 static void SetDelegate(ID identifier, BrowserThreadDelegate* delegate); | |
209 | |
210 // Use these templates in conjuction with RefCountedThreadSafe when you want | 173 // Use these templates in conjuction with RefCountedThreadSafe when you want |
211 // to ensure that an object is deleted on a specific thread. This is needed | 174 // to ensure that an object is deleted on a specific thread. This is needed |
212 // when an object can hop between threads (i.e. IO -> FILE -> IO), and thread | 175 // when an object can hop between threads (i.e. IO -> FILE -> IO), and thread |
213 // switching delays can mean that the final IO tasks executes before the FILE | 176 // switching delays can mean that the final IO tasks executes before the FILE |
214 // task's stack unwinds. This would lead to the object destructing on the | 177 // task's stack unwinds. This would lead to the object destructing on the |
215 // FILE thread, which often is not what you want (i.e. to unregister from | 178 // FILE thread, which often is not what you want (i.e. to unregister from |
216 // NotificationService, to notify other objects on the creating thread etc). | 179 // NotificationService, to notify other objects on the creating thread etc). |
217 template<ID thread> | 180 template<ID thread> |
218 struct DeleteOnThread { | 181 struct DeleteOnThread { |
219 template<typename T> | 182 template<typename T> |
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243 // friend class DeleteTask<Foo>; | 206 // friend class DeleteTask<Foo>; |
244 // | 207 // |
245 // ~Foo(); | 208 // ~Foo(); |
246 struct DeleteOnUIThread : public DeleteOnThread<UI> { }; | 209 struct DeleteOnUIThread : public DeleteOnThread<UI> { }; |
247 struct DeleteOnIOThread : public DeleteOnThread<IO> { }; | 210 struct DeleteOnIOThread : public DeleteOnThread<IO> { }; |
248 struct DeleteOnFileThread : public DeleteOnThread<FILE> { }; | 211 struct DeleteOnFileThread : public DeleteOnThread<FILE> { }; |
249 struct DeleteOnDBThread : public DeleteOnThread<DB> { }; | 212 struct DeleteOnDBThread : public DeleteOnThread<DB> { }; |
250 struct DeleteOnWebKitThread : public DeleteOnThread<WEBKIT> { }; | 213 struct DeleteOnWebKitThread : public DeleteOnThread<WEBKIT> { }; |
251 | 214 |
252 private: | 215 private: |
253 friend class BrowserThreadImpl; | 216 // Construct a BrowserThread with the supplied identifier. It is an error |
| 217 // to construct a BrowserThread that already exists. |
| 218 explicit BrowserThread(ID identifier); |
254 | 219 |
255 BrowserThread() {} | 220 // Special constructor for the main (UI) thread and unittests. We use a dummy |
256 DISALLOW_COPY_AND_ASSIGN(BrowserThread); | 221 // thread here since the main thread already exists. |
| 222 BrowserThread(ID identifier, MessageLoop* message_loop); |
| 223 |
| 224 virtual ~BrowserThread(); |
| 225 |
| 226 // Common initialization code for the constructors. |
| 227 void Initialize(); |
| 228 |
| 229 // Constructors are only available through this subclass. |
| 230 friend class content::BrowserThreadImpl; |
| 231 |
| 232 // TODO(joi): Remove. |
| 233 friend class DeprecatedBrowserThread; |
| 234 |
| 235 // The identifier of this thread. Only one thread can exist with a given |
| 236 // identifier at a given time. |
| 237 // TODO(joi): Move to BrowserThreadImpl, and make constructors here |
| 238 // do-nothing. |
| 239 ID identifier_; |
| 240 }; |
| 241 |
| 242 // Temporary escape hatch for chrome/ to construct BrowserThread, |
| 243 // until we make content/ construct its own threads. |
| 244 class CONTENT_EXPORT DeprecatedBrowserThread : public BrowserThread { |
| 245 public: |
| 246 explicit DeprecatedBrowserThread(BrowserThread::ID identifier); |
| 247 DeprecatedBrowserThread(BrowserThread::ID identifier, |
| 248 MessageLoop* message_loop); |
| 249 virtual ~DeprecatedBrowserThread(); |
257 }; | 250 }; |
258 | 251 |
259 } // namespace content | 252 } // namespace content |
260 | 253 |
261 #endif // CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ | 254 #endif // CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_ |
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