#ifndef MessageQueue_h
#define MessageQueue_h
#include <limits>
#include <wtf/Assertions.h>
#include <wtf/Deque.h>
#include <wtf/Noncopyable.h>
#include <wtf/Threading.h>
namespace WTF {
enum MessageQueueWaitResult {
MessageQueueTerminated, MessageQueueTimeout, MessageQueueMessageReceived, };
template<typename DataType>
class MessageQueue : Noncopyable {
public:
MessageQueue() : m_killed(false) {}
void append(const DataType&);
void prepend(const DataType&);
bool waitForMessage(DataType&);
template<typename Predicate>
MessageQueueWaitResult waitForMessageFilteredWithTimeout(DataType&, Predicate&, double absoluteTime);
void kill();
bool tryGetMessage(DataType&);
bool killed() const;
bool isEmpty();
static double infiniteTime() { return std::numeric_limits<double>::max(); }
private:
static bool alwaysTruePredicate(DataType&) { return true; }
mutable Mutex m_mutex;
ThreadCondition m_condition;
Deque<DataType> m_queue;
bool m_killed;
};
template<typename DataType>
inline void MessageQueue<DataType>::append(const DataType& message)
{
MutexLocker lock(m_mutex);
m_queue.append(message);
m_condition.signal();
}
template<typename DataType>
inline void MessageQueue<DataType>::prepend(const DataType& message)
{
MutexLocker lock(m_mutex);
m_queue.prepend(message);
m_condition.signal();
}
template<typename DataType>
inline bool MessageQueue<DataType>::waitForMessage(DataType& result)
{
MessageQueueWaitResult exitReason = waitForMessageFilteredWithTimeout(result, MessageQueue<DataType>::alwaysTruePredicate, infiniteTime());
ASSERT(exitReason == MessageQueueTerminated || exitReason == MessageQueueMessageReceived);
return exitReason == MessageQueueMessageReceived;
}
template<typename DataType>
template<typename Predicate>
inline MessageQueueWaitResult MessageQueue<DataType>::waitForMessageFilteredWithTimeout(DataType& result, Predicate& predicate, double absoluteTime)
{
MutexLocker lock(m_mutex);
bool timedOut = false;
DequeConstIterator<DataType> found = m_queue.end();
while (!m_killed && !timedOut && (found = m_queue.findIf(predicate)) == m_queue.end())
timedOut = !m_condition.timedWait(m_mutex, absoluteTime);
ASSERT(!timedOut || absoluteTime != infiniteTime());
if (m_killed)
return MessageQueueTerminated;
if (timedOut)
return MessageQueueTimeout;
ASSERT(found != m_queue.end());
result = *found;
m_queue.remove(found);
return MessageQueueMessageReceived;
}
template<typename DataType>
inline bool MessageQueue<DataType>::tryGetMessage(DataType& result)
{
MutexLocker lock(m_mutex);
if (m_killed)
return false;
if (m_queue.isEmpty())
return false;
result = m_queue.first();
m_queue.removeFirst();
return true;
}
template<typename DataType>
inline bool MessageQueue<DataType>::isEmpty()
{
MutexLocker lock(m_mutex);
if (m_killed)
return true;
return m_queue.isEmpty();
}
template<typename DataType>
inline void MessageQueue<DataType>::kill()
{
MutexLocker lock(m_mutex);
m_killed = true;
m_condition.broadcast();
}
template<typename DataType>
inline bool MessageQueue<DataType>::killed() const
{
MutexLocker lock(m_mutex);
return m_killed;
}
}
using WTF::MessageQueue;
using WTF::MessageQueueWaitResult;
using WTF::MessageQueueTerminated;
using WTF::MessageQueueTimeout;
using WTF::MessageQueueMessageReceived;
#endif // MessageQueue_h