// Copyright (c) 2006-2008 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/waitable_event.h"

#include <math.h>
#include <windows.h>

#include "base/logging.h"
#include "base/time.h"

namespace base {

WaitableEvent::WaitableEvent(bool manual_reset, bool signaled)
    : event_(CreateEvent(NULL, manual_reset, signaled, NULL)) {
  // We're probably going to crash anyways if this is ever NULL, so we might as
  // well make our stack reports more informative by crashing here.
  CHECK(event_);
}

WaitableEvent::~WaitableEvent() {
  CloseHandle(event_);
}

void WaitableEvent::Reset() {
  ResetEvent(event_);
}

void WaitableEvent::Signal() {
  SetEvent(event_);
}

bool WaitableEvent::IsSignaled() {
  return TimedWait(TimeDelta::FromMilliseconds(0));
}

bool WaitableEvent::Wait() {
  DWORD result = WaitForSingleObject(event_, INFINITE);
  // It is most unexpected that this should ever fail.  Help consumers learn
  // about it if it should ever fail.
  DCHECK(result == WAIT_OBJECT_0) << "WaitForSingleObject failed";
  return result == WAIT_OBJECT_0;
}

bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
  DCHECK(max_time >= TimeDelta::FromMicroseconds(0));
  // Be careful here.  TimeDelta has a precision of microseconds, but this API
  // is in milliseconds.  If there are 5.5ms left, should the delay be 5 or 6?
  // It should be 6 to avoid returning too early.
  double timeout = ceil(max_time.InMillisecondsF());
  DWORD result = WaitForSingleObject(event_, static_cast<DWORD>(timeout));
  switch (result) {
    case WAIT_OBJECT_0:
      return true;
    case WAIT_TIMEOUT:
      return false;
  }
  // It is most unexpected that this should ever fail.  Help consumers learn
  // about it if it should ever fail.
  NOTREACHED() << "WaitForSingleObject failed";
  return false;
}

}  // namespace base