#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 {
WTF_MAKE_NONCOPYABLE(MessageQueue);
public:
MessageQueue() : m_killed(false) { }
~MessageQueue();
void append(PassOwnPtr<DataType>);
bool appendAndCheckEmpty(PassOwnPtr<DataType>);
void prepend(PassOwnPtr<DataType>);
PassOwnPtr<DataType> waitForMessage();
PassOwnPtr<DataType> tryGetMessage();
template<typename Predicate>
PassOwnPtr<DataType> waitForMessageFilteredWithTimeout(MessageQueueWaitResult&, Predicate&, double absoluteTime);
template<typename Predicate>
void removeIf(Predicate&);
void kill();
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>
MessageQueue<DataType>::~MessageQueue()
{
deleteAllValues(m_queue);
}
template<typename DataType>
inline void MessageQueue<DataType>::append(PassOwnPtr<DataType> message)
{
MutexLocker lock(m_mutex);
m_queue.append(message.leakPtr());
m_condition.signal();
}
template<typename DataType>
inline bool MessageQueue<DataType>::appendAndCheckEmpty(PassOwnPtr<DataType> message)
{
MutexLocker lock(m_mutex);
bool wasEmpty = m_queue.isEmpty();
m_queue.append(message.leakPtr());
m_condition.signal();
return wasEmpty;
}
template<typename DataType>
inline void MessageQueue<DataType>::prepend(PassOwnPtr<DataType> message)
{
MutexLocker lock(m_mutex);
m_queue.prepend(message.leakPtr());
m_condition.signal();
}
template<typename DataType>
inline PassOwnPtr<DataType> MessageQueue<DataType>::waitForMessage()
{
MessageQueueWaitResult exitReason;
OwnPtr<DataType> result = waitForMessageFilteredWithTimeout(exitReason, MessageQueue<DataType>::alwaysTruePredicate, infiniteTime());
ASSERT(exitReason == MessageQueueTerminated || exitReason == MessageQueueMessageReceived);
return result.release();
}
template<typename DataType>
template<typename Predicate>
inline PassOwnPtr<DataType> MessageQueue<DataType>::waitForMessageFilteredWithTimeout(MessageQueueWaitResult& 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) {
result = MessageQueueTerminated;
return nullptr;
}
if (timedOut) {
result = MessageQueueTimeout;
return nullptr;
}
ASSERT(found != m_queue.end());
OwnPtr<DataType> message = adoptPtr(*found);
m_queue.remove(found);
result = MessageQueueMessageReceived;
return message.release();
}
template<typename DataType>
inline PassOwnPtr<DataType> MessageQueue<DataType>::tryGetMessage()
{
MutexLocker lock(m_mutex);
if (m_killed)
return nullptr;
if (m_queue.isEmpty())
return nullptr;
return adoptPtr(m_queue.takeFirst());
}
template<typename DataType>
template<typename Predicate>
inline void MessageQueue<DataType>::removeIf(Predicate& predicate)
{
MutexLocker lock(m_mutex);
while (true) {
DequeConstIterator<DataType*> found = m_queue.findIf(predicate);
if (found == m_queue.end())
break;
DataType* message = *found;
m_queue.remove(found);
delete message;
}
}
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