1 files changed, 40 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/synchronization/lock_impl_win.cc b/security/sandbox/chromium/base/synchronization/lock_impl_win.cc
new file mode 100644
index 0000000000..e0c4e9d7fc
--- /dev/null
+++ b/security/sandbox/chromium/base/synchronization/lock_impl_win.cc
@@ -0,0 +1,40 @@
+// Copyright (c) 2011 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 "base/synchronization/lock_impl.h"
+
+#include "base/debug/activity_tracker.h"
+
+#include <windows.h>
+
+namespace base {
+namespace internal {
+
+LockImpl::LockImpl() : native_handle_(SRWLOCK_INIT) {}
+
+LockImpl::~LockImpl() = default;
+
+bool LockImpl::Try() {
+  return !!::TryAcquireSRWLockExclusive(
+      reinterpret_cast<PSRWLOCK>(&native_handle_));
+}
+
+void LockImpl::Lock() {
+  // The ScopedLockAcquireActivity below is relatively expensive and so its
+  // actions can become significant due to the very large number of locks
+  // that tend to be used throughout the build. To avoid this cost in the
+  // vast majority of the calls, simply "try" the lock first and only do the
+  // (tracked) blocking call if that fails. Since "try" itself is a system
+  // call, and thus also somewhat expensive, don't bother with it unless
+  // tracking is actually enabled.
+  if (base::debug::GlobalActivityTracker::IsEnabled())
+    if (Try())
+      return;
+
+  base::debug::ScopedLockAcquireActivity lock_activity(this);
+  ::AcquireSRWLockExclusive(reinterpret_cast<PSRWLOCK>(&native_handle_));
+}
+
+}  // namespace internal
+}  // namespace base