Rename AtomicFlag to CancelFlag, change its semantics a bit

Review URL: http://codereview.chromium.org/454025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33723 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 42 insertions, 0 deletions

diff --git a/base/cancellation_flag.h b/base/cancellation_flag.h
new file mode 100644
index 0000000..b9c045d
--- /dev/null
+++ b/base/cancellation_flag.h
@@ -0,0 +1,42 @@
+// 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 BASE_CANCELLATION_FLAG_H_
+#define BASE_CANCELLATION_FLAG_H_
+
+#include "base/atomicops.h"
+#include "base/platform_thread.h"
+
+namespace base {
+
+// CancellationFlag allows one thread to cancel jobs executed on some worker
+// thread. Calling Set() from one thread and IsSet() from a number of threads
+// is thread-safe.
+//
+// This class IS NOT intended for synchronization between threads.
+class CancellationFlag {
+ public:
+  CancellationFlag() : flag_(false) {
+#if !defined(NDEBUG)
+    set_on_ = PlatformThread::CurrentId();
+#endif
+  }
+  ~CancellationFlag() {}
+
+  // Set the flag. May only be called on the thread which owns the object.
+  void Set();
+  bool IsSet() const;  // Returns true iff the flag was set.
+
+ private:
+  base::subtle::Atomic32 flag_;
+#if !defined(NDEBUG)
+  PlatformThreadId set_on_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(CancellationFlag);
+};
+
+}  // namespace base
+
+#endif  // BASE_CANCELLATION_FLAG_H_