// 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