Source/WebKit/Shared/BlockingResponseMap.h

/*
 * Copyright (C) 2012 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef BlockingResponseMap_h
#define BlockingResponseMap_h

#include <wtf/Condition.h>
#include <wtf/HashMap.h>
#include <wtf/Lock.h>
#include <wtf/Noncopyable.h>

template<typename T>
class BlockingResponseMap {
WTF_MAKE_NONCOPYABLE(BlockingResponseMap);
public:
    BlockingResponseMap() : m_canceled(false) { }
    ~BlockingResponseMap() { ASSERT(m_responses.isEmpty()); }

    std::unique_ptr<T> waitForResponse(uint64_t requestID)
    {
        while (true) {
            Locker locker { m_responsesLock };

            if (m_canceled)
                return nullptr;

            if (std::unique_ptr<T> response = m_responses.take(requestID))
                return response;

            m_condition.wait(m_responsesLock);
        }

        return nullptr;
    }

    void didReceiveResponse(uint64_t requestID, std::unique_ptr<T> response)
    {
        Locker locker { m_responsesLock };
        ASSERT(!m_responses.contains(requestID));

        m_responses.set(requestID, WTFMove(response));

        // FIXME: Could get a slight speed-up from using notifyOne().
        m_condition.notifyAll();
    }

    void cancel()
    {
        m_canceled = true;

        // FIXME: Could get a slight speed-up from using notifyOne().
        m_condition.notifyAll();
    }

private:
    Lock m_responsesLock;
    Condition m_condition;

    HashMap<uint64_t, std::unique_ptr<T>> m_responses WTF_GUARDED_BY_LOCK(m_responsesLock);
    bool m_canceled;
};

#endif // BlockingResponseMap_h