webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

1 files changed, 237 insertions, 0 deletions

diff --git a/Source/WTF/wtf/ParallelHelperPool.cpp b/Source/WTF/wtf/ParallelHelperPool.cpp
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+++ b/Source/WTF/wtf/ParallelHelperPool.cpp
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+/*
+ * Copyright (C) 2015-2017 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. ``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
+ * 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. 
+ */
+
+#include "config.h"
+#include "ParallelHelperPool.h"
+
+#include "AutomaticThread.h"
+#include "DataLog.h"
+#include "StringPrintStream.h"
+
+namespace WTF {
+
+ParallelHelperClient::ParallelHelperClient(RefPtr<ParallelHelperPool> pool)
+    : m_pool(pool)
+{
+    LockHolder locker(*m_pool->m_lock);
+    RELEASE_ASSERT(!m_pool->m_isDying);
+    m_pool->m_clients.append(this);
+}
+
+ParallelHelperClient::~ParallelHelperClient()
+{
+    LockHolder locker(*m_pool->m_lock);
+    finish(locker);
+
+    for (size_t i = 0; i < m_pool->m_clients.size(); ++i) {
+        if (m_pool->m_clients[i] == this) {
+            m_pool->m_clients[i] = m_pool->m_clients.last();
+            m_pool->m_clients.removeLast();
+            break;
+        }
+    }
+}
+
+void ParallelHelperClient::setTask(RefPtr<SharedTask<void ()>> task)
+{
+    LockHolder locker(*m_pool->m_lock);
+    RELEASE_ASSERT(!m_task);
+    m_task = task;
+    m_pool->didMakeWorkAvailable(locker);
+}
+
+void ParallelHelperClient::finish()
+{
+    LockHolder locker(*m_pool->m_lock);
+    finish(locker);
+}
+
+void ParallelHelperClient::doSomeHelping()
+{
+    RefPtr<SharedTask<void ()>> task;
+    {
+        LockHolder locker(*m_pool->m_lock);
+        task = claimTask(locker);
+        if (!task)
+            return;
+    }
+
+    runTask(task);
+}
+
+void ParallelHelperClient::runTaskInParallel(RefPtr<SharedTask<void ()>> task)
+{
+    setTask(task);
+    doSomeHelping();
+    finish();
+}
+
+void ParallelHelperClient::finish(const AbstractLocker&)
+{
+    m_task = nullptr;
+    while (m_numActive)
+        m_pool->m_workCompleteCondition.wait(*m_pool->m_lock);
+}
+
+RefPtr<SharedTask<void ()>> ParallelHelperClient::claimTask(const AbstractLocker&)
+{
+    if (!m_task)
+        return nullptr;
+    
+    m_numActive++;
+    return m_task;
+}
+
+void ParallelHelperClient::runTask(RefPtr<SharedTask<void ()>> task)
+{
+    RELEASE_ASSERT(m_numActive);
+    RELEASE_ASSERT(task);
+
+    task->run();
+
+    {
+        LockHolder locker(*m_pool->m_lock);
+        RELEASE_ASSERT(m_numActive);
+        // No new task could have been installed, since we were still active.
+        RELEASE_ASSERT(!m_task || m_task == task);
+        m_task = nullptr;
+        m_numActive--;
+        if (!m_numActive)
+            m_pool->m_workCompleteCondition.notifyAll();
+    }
+}
+
+ParallelHelperPool::ParallelHelperPool()
+    : m_lock(Box<Lock>::create())
+    , m_workAvailableCondition(AutomaticThreadCondition::create())
+{
+}
+
+ParallelHelperPool::~ParallelHelperPool()
+{
+    RELEASE_ASSERT(m_clients.isEmpty());
+    
+    {
+        LockHolder locker(*m_lock);
+        m_isDying = true;
+        m_workAvailableCondition->notifyAll(locker);
+    }
+
+    for (RefPtr<AutomaticThread>& thread : m_threads)
+        thread->join();
+}
+
+void ParallelHelperPool::ensureThreads(unsigned numThreads)
+{
+    LockHolder locker(*m_lock);
+    if (numThreads < m_numThreads)
+        return;
+    m_numThreads = numThreads;
+    if (getClientWithTask(locker))
+        didMakeWorkAvailable(locker);
+}
+
+void ParallelHelperPool::doSomeHelping()
+{
+    ParallelHelperClient* client;
+    RefPtr<SharedTask<void ()>> task;
+    {
+        LockHolder locker(*m_lock);
+        client = getClientWithTask(locker);
+        if (!client)
+            return;
+        task = client->claimTask(locker);
+    }
+
+    client->runTask(task);
+}
+
+class ParallelHelperPool::Thread : public AutomaticThread {
+public:
+    Thread(const AbstractLocker& locker, ParallelHelperPool& pool)
+        : AutomaticThread(locker, pool.m_lock, pool.m_workAvailableCondition)
+        , m_pool(pool)
+    {
+    }
+    
+protected:
+    PollResult poll(const AbstractLocker& locker) override
+    {
+        if (m_pool.m_isDying)
+            return PollResult::Stop;
+        m_client = m_pool.getClientWithTask(locker);
+        if (m_client) {
+            m_task = m_client->claimTask(locker);
+            return PollResult::Work;
+        }
+        return PollResult::Wait;
+    }
+    
+    WorkResult work() override
+    {
+        m_client->runTask(m_task);
+        m_client = nullptr;
+        m_task = nullptr;
+        return WorkResult::Continue;
+    }
+    
+private:
+    ParallelHelperPool& m_pool;
+    ParallelHelperClient* m_client { nullptr };
+    RefPtr<SharedTask<void ()>> m_task;
+};
+
+void ParallelHelperPool::didMakeWorkAvailable(const AbstractLocker& locker)
+{
+    while (m_numThreads > m_threads.size())
+        m_threads.append(adoptRef(new Thread(locker, *this)));
+    m_workAvailableCondition->notifyAll(locker);
+}
+
+bool ParallelHelperPool::hasClientWithTask(const AbstractLocker& locker)
+{
+    return !!getClientWithTask(locker);
+}
+
+ParallelHelperClient* ParallelHelperPool::getClientWithTask(const AbstractLocker&)
+{
+    // We load-balance by being random.
+    unsigned startIndex = m_random.getUint32(m_clients.size());
+    for (unsigned index = startIndex; index < m_clients.size(); ++index) {
+        ParallelHelperClient* client = m_clients[index];
+        if (client->m_task)
+            return client;
+    }
+    for (unsigned index = 0; index < startIndex; ++index) {
+        ParallelHelperClient* client = m_clients[index];
+        if (client->m_task)
+            return client;
+    }
+
+    return nullptr;
+}
+
+} // namespace WTF
+