Index: base/thread_restrictions.h |
=================================================================== |
--- base/thread_restrictions.h (revision 70342) |
+++ base/thread_restrictions.h (working copy) |
@@ -1,100 +0,0 @@ |
-// Copyright (c) 2010 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 BASE_THREAD_RESTRICTIONS_H_ |
-#define BASE_THREAD_RESTRICTIONS_H_ |
- |
-#include "base/basictypes.h" |
- |
-namespace base { |
- |
-// Certain behavior is disallowed on certain threads. ThreadRestrictions helps |
-// enforce these rules. Examples of such rules: |
-// |
-// * Do not do blocking IO (makes the thread janky) |
-// * Do not access Singleton/LazyInstance (may lead to shutdown crashes) |
-// |
-// Here's more about how the protection works: |
-// |
-// 1) If a thread should not be allowed to make IO calls, mark it: |
-// base::ThreadRestrictions::SetIOAllowed(false); |
-// By default, threads *are* allowed to make IO calls. |
-// In Chrome browser code, IO calls should be proxied to the File thread. |
-// |
-// 2) If a function makes a call that will go out to disk, check whether the |
-// current thread is allowed: |
-// base::ThreadRestrictions::AssertIOAllowed(); |
-// |
-// ThreadRestrictions does nothing in release builds; it is debug-only. |
-// |
-// Style tip: where should you put AssertIOAllowed checks? It's best |
-// if you put them as close to the disk access as possible, at the |
-// lowest level. This rule is simple to follow and helps catch all |
-// callers. For example, if your function GoDoSomeBlockingDiskCall() |
-// only calls other functions in Chrome and not fopen(), you should go |
-// add the AssertIOAllowed checks in the helper functions. |
- |
-class ThreadRestrictions { |
- public: |
- // Constructing a ScopedAllowIO temporarily allows IO for the current |
- // thread. Doing this is almost certainly always incorrect. |
- class ScopedAllowIO { |
- public: |
- ScopedAllowIO() { previous_value_ = SetIOAllowed(true); } |
- ~ScopedAllowIO() { SetIOAllowed(previous_value_); } |
- private: |
- // Whether IO is allowed when the ScopedAllowIO was constructed. |
- bool previous_value_; |
- |
- DISALLOW_COPY_AND_ASSIGN(ScopedAllowIO); |
- }; |
- |
- // Constructing a ScopedAllowSingleton temporarily allows accessing for the |
- // current thread. Doing this is almost always incorrect. |
- class ScopedAllowSingleton { |
- public: |
- ScopedAllowSingleton() { previous_value_ = SetSingletonAllowed(true); } |
- ~ScopedAllowSingleton() { SetSingletonAllowed(previous_value_); } |
- private: |
- // Whether singleton use is allowed when the ScopedAllowSingleton was |
- // constructed. |
- bool previous_value_; |
- |
- DISALLOW_COPY_AND_ASSIGN(ScopedAllowSingleton); |
- }; |
- |
-#ifndef NDEBUG |
- // Set whether the current thread to make IO calls. |
- // Threads start out in the *allowed* state. |
- // Returns the previous value. |
- static bool SetIOAllowed(bool allowed); |
- |
- // Check whether the current thread is allowed to make IO calls, |
- // and DCHECK if not. See the block comment above the class for |
- // a discussion of where to add these checks. |
- static void AssertIOAllowed(); |
- |
- // Set whether the current thread can use singletons. Returns the previous |
- // value. |
- static bool SetSingletonAllowed(bool allowed); |
- |
- // Check whether the current thread is allowed to use singletons (Singleton / |
- // LazyInstance). DCHECKs if not. |
- static void AssertSingletonAllowed(); |
-#else |
- // In Release builds, inline the empty definitions of these functions so |
- // that they can be compiled out. |
- static bool SetIOAllowed(bool allowed) { return true; } |
- static void AssertIOAllowed() {} |
- static bool SetSingletonAllowed(bool allowed) { return true; } |
- static void AssertSingletonAllowed() {} |
-#endif |
- |
- private: |
- DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions); |
-}; |
- |
-} // namespace base |
- |
-#endif // BASE_THREAD_RESTRICTIONS_H_ |