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Unified Diff: base/thread_restrictions.h

Issue 6028009: Move base/thread.h to base/threading, fix up callers to use the new location.... (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: Created 10 years ago
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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_
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