#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(std::unique_ptr<DataType>);
void appendAndKill(std::unique_ptr<DataType>);
bool appendAndCheckEmpty(std::unique_ptr<DataType>);
void prepend(std::unique_ptr<DataType>);
std::unique_ptr<DataType> waitForMessage();
std::unique_ptr<DataType> tryGetMessage();
std::unique_ptr<DataType> tryGetMessageIgnoringKilled();
template<typename Predicate>
std::unique_ptr<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:
mutable Mutex m_mutex;
ThreadCondition m_condition;
Deque<std::unique_ptr<DataType>> m_queue;
bool m_killed;
};
template<typename DataType>
MessageQueue<DataType>::~MessageQueue()
{
}
template<typename DataType>
inline void MessageQueue<DataType>::append(std::unique_ptr<DataType> message)
{
MutexLocker lock(m_mutex);
m_queue.append(WTF::move(message));
m_condition.signal();
}
template<typename DataType>
inline void MessageQueue<DataType>::appendAndKill(std::unique_ptr<DataType> message)
{
MutexLocker lock(m_mutex);
m_queue.append(WTF::move(message));
m_killed = true;
m_condition.broadcast();
}
template<typename DataType>
inline bool MessageQueue<DataType>::appendAndCheckEmpty(std::unique_ptr<DataType> message)
{
MutexLocker lock(m_mutex);
bool wasEmpty = m_queue.isEmpty();
m_queue.append(WTF::move(message));
m_condition.signal();
return wasEmpty;
}
template<typename DataType>
inline void MessageQueue<DataType>::prepend(std::unique_ptr<DataType> message)
{
MutexLocker lock(m_mutex);
m_queue.prepend(WTF::move(message));
m_condition.signal();
}
template<typename DataType>
inline auto MessageQueue<DataType>::waitForMessage() -> std::unique_ptr<DataType>
{
MessageQueueWaitResult exitReason;
std::unique_ptr<DataType> result = waitForMessageFilteredWithTimeout(exitReason, [](const DataType&) { return true; }, infiniteTime());
ASSERT(exitReason == MessageQueueTerminated || exitReason == MessageQueueMessageReceived);
return result;
}
template<typename DataType>
template<typename Predicate>
inline auto MessageQueue<DataType>::waitForMessageFilteredWithTimeout(MessageQueueWaitResult& result, Predicate&& predicate, double absoluteTime) -> std::unique_ptr<DataType>
{
MutexLocker lock(m_mutex);
bool timedOut = false;
auto found = m_queue.end();
while (!m_killed && !timedOut) {
found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
ASSERT(ptr);
return predicate(*ptr);
});
if (found != m_queue.end())
break;
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());
std::unique_ptr<DataType> message = WTF::move(*found);
m_queue.remove(found);
result = MessageQueueMessageReceived;
return message;
}
template<typename DataType>
inline auto MessageQueue<DataType>::tryGetMessage() -> std::unique_ptr<DataType>
{
MutexLocker lock(m_mutex);
if (m_killed)
return nullptr;
if (m_queue.isEmpty())
return nullptr;
return m_queue.takeFirst();
}
template<typename DataType>
inline auto MessageQueue<DataType>::tryGetMessageIgnoringKilled() -> std::unique_ptr<DataType>
{
MutexLocker lock(m_mutex);
if (m_queue.isEmpty())
return nullptr;
return m_queue.takeFirst();
}
template<typename DataType>
template<typename Predicate>
inline void MessageQueue<DataType>::removeIf(Predicate&& predicate)
{
MutexLocker lock(m_mutex);
while (true) {
auto found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
ASSERT(ptr);
return predicate(*ptr);
});
if (found == m_queue.end())
break;
m_queue.remove(found);
}
}
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