Create 2272 release branch for CEF3.

git-svn-id: https://chromiumembedded.googlecode.com/svn/branches/2272@1993 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

libcef_dll/base/cef_thread_collision_warner.cc

@@ -0,0 +1,65 @@
+// 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.
+
+#include "include/base/cef_thread_collision_warner.h"
+
+#include "include/base/cef_logging.h"
+#include "include/internal/cef_thread_internal.h"
+
+namespace base {
+
+void DCheckAsserter::warn() {
+  NOTREACHED() << "Thread Collision";
+}
+
+static subtle::Atomic32 CurrentThread() {
+  const cef_platform_thread_id_t current_thread_id =
+      cef_get_current_platform_thread_id();
+  // We need to get the thread id into an atomic data type. This might be a
+  // truncating conversion, but any loss-of-information just increases the
+  // chance of a fault negative, not a false positive.
+  const subtle::Atomic32 atomic_thread_id =
+      static_cast<subtle::Atomic32>(current_thread_id);
+
+  return atomic_thread_id;
+}
+
+void ThreadCollisionWarner::EnterSelf() {
+  // If the active thread is 0 then I'll write the current thread ID
+  // if two or more threads arrive here only one will succeed to
+  // write on valid_thread_id_ the current thread ID.
+  subtle::Atomic32 current_thread_id = CurrentThread();
+
+  int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
+                                                        0,
+                                                        current_thread_id);
+  if (previous_value != 0 && previous_value != current_thread_id) {
+    // gotcha! a thread is trying to use the same class and that is
+    // not current thread.
+    asserter_->warn();
+  }
+
+  subtle::NoBarrier_AtomicIncrement(&counter_, 1);
+}
+
+void ThreadCollisionWarner::Enter() {
+  subtle::Atomic32 current_thread_id = CurrentThread();
+
+  if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
+                                       0,
+                                       current_thread_id) != 0) {
+    // gotcha! another thread is trying to use the same class.
+    asserter_->warn();
+  }
+
+  subtle::NoBarrier_AtomicIncrement(&counter_, 1);
+}
+
+void ThreadCollisionWarner::Leave() {
+  if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {
+    subtle::NoBarrier_Store(&valid_thread_id_, 0);
+  }
+}
+
+}  // namespace base