Move CrossThreadHolder to CrossThreadHolder.h

Source/modules/fetch/FetchBlobDataConsumerHandle.cpp

Index: Source/modules/fetch/FetchBlobDataConsumerHandle.cpp
diff --git a/Source/modules/fetch/FetchBlobDataConsumerHandle.cpp b/Source/modules/fetch/FetchBlobDataConsumerHandle.cpp
index 9005fb551944f0fc283f8c371eaa5be99f5a03fb..f3b9f284df1afb5630f6e48629af5443f1e0d196 100644
--- a/Source/modules/fetch/FetchBlobDataConsumerHandle.cpp
+++ b/Source/modules/fetch/FetchBlobDataConsumerHandle.cpp
@@ -5,21 +5,15 @@
 #include "config.h"
 #include "modules/fetch/FetchBlobDataConsumerHandle.h"
 
-#include "core/dom/ActiveDOMObject.h"
-#include "core/dom/CrossThreadTask.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/fetch/FetchInitiatorTypeNames.h"
 #include "core/loader/ThreadableLoaderClient.h"
 #include "modules/fetch/CompositeDataConsumerHandle.h"
+#include "modules/fetch/CrossThreadHolder.h"
 #include "modules/fetch/DataConsumerHandleUtil.h"
-#include "platform/Task.h"
 #include "platform/blob/BlobRegistry.h"
 #include "platform/blob/BlobURL.h"
 #include "platform/network/ResourceRequest.h"
-#include "public/platform/Platform.h"
-#include "public/platform/WebTraceLocation.h"
-#include "wtf/Locker.h"
-#include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
 
@@ -27,160 +21,6 @@ using Result = FetchBlobDataConsumerHandle::Result;
 
 namespace {
 
-// CrossThreadHolder<T> provides cross-thread access to |obj| of class T
-// bound to the thread of |executionContext| where |obj| is created.
-// - CrossThreadHolder<T> can be passed across threads.
-// - |obj|'s methods are called on the thread of |executionContext|
-//   via CrossThreadHolder<T>::postTask().
-// - |obj| is destructed on the thread of |executionContext|
-//   when |executionContext| is stopped or
-//   CrossThreadHolder is destructed (earlier of them).
-//   Note: |obj|'s destruction can be slightly after CrossThreadHolder.
-template<typename T>
-class CrossThreadHolder {
-public:
-    // Must be called on the thread where |obj| is created
-    // (== the thread of |executionContext|).
-    // The current thread must be attached to Oilpan.
-    static PassOwnPtr<CrossThreadHolder<T>> create(ExecutionContext* executionContext, PassOwnPtr<T> obj)
-    {
-        ASSERT(executionContext->isContextThread());
-        return adoptPtr(new CrossThreadHolder(executionContext, obj));
-    }
-
-    // Can be called from any thread.
-    // Executes |task| with |obj| and |executionContext| on the thread of
-    // |executionContext|.
-    // NOTE: |task| might be silently ignored (i.e. not executed) and
-    // destructed (possibly on the calling thread or on the thread of
-    // |executionContext|) when |executionContext| is stopped or
-    // CrossThreadHolder is destructed.
-    void postTask(PassOwnPtr<WTF::Function<void(T*, ExecutionContext*)>> task)
-    {
-        MutexLocker locker(m_mutex->mutex());
-        if (!m_bridge) {
-            // The bridge has already disappeared.
-            return;
-        }
-        m_bridge->executionContext()->postTask(FROM_HERE, createCrossThreadTask(&Bridge::runTask, m_bridge.get(), task));
-    }
-
-    ~CrossThreadHolder()
-    {
-        MutexLocker locker(m_mutex->mutex());
-        clearInternal();
-    }
-
-private:
-    // Object graph:
-    //                 +------+                          +-----------------+
-    //     T <-OwnPtr- |Bridge| ---------RawPtr--------> |CrossThreadHolder|
-    //                 |      | <-CrossThreadPersistent- |                 |
-    //                 +------+                          +-----------------+
-    //                    |                                    |
-    //                    +--RefPtr--> MutexWrapper <--RefPtr--+
-    // The CrossThreadPersistent/RawPtr between CrossThreadHolder and Bridge
-    // are protected by MutexWrapper
-    // and cleared when CrossThreadHolder::clearInternal() is called, i.e.:
-    // [1] when |executionContext| is stopped, or
-    // [2] when CrossThreadHolder is destructed.
-    // Then Bridge is shortly garbage collected and T is destructed.
-
-    class MutexWrapper : public ThreadSafeRefCounted<MutexWrapper> {
-    public:
-        static PassRefPtr<MutexWrapper> create() { return adoptRef(new MutexWrapper()); }
-        Mutex& mutex() { return m_mutex; }
-    private:
-        MutexWrapper() = default;
-        Mutex m_mutex;
-    };
-
-    // All methods except for clearInternal()
-    // must be called on |executionContext|'s thread.
-    class Bridge
-        : public GarbageCollectedFinalized<Bridge>
-        , public ActiveDOMObject {
-        WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(Bridge);
-    public:
-        Bridge(ExecutionContext* executionContext, PassOwnPtr<T> obj, PassRefPtr<MutexWrapper> mutex, CrossThreadHolder* holder)
-            : ActiveDOMObject(executionContext)
-            , m_obj(obj)
-            , m_mutex(mutex)
-            , m_holder(holder)
-        {
-            suspendIfNeeded();
-        }
-
-        DEFINE_INLINE_TRACE()
-        {
-            ActiveDOMObject::trace(visitor);
-        }
-
-        T* getObject() const { return m_obj.get(); }
-
-        // Must be protected by |m_mutex|.
-        // Is called from CrossThreadHolder::clearInternal() and
-        // can be called on any thread.
-        void clearInternal()
-        {
-            // We don't clear |m_obj| here to destruct |m_obj| on the thread
-            // of |executionContext|.
-            m_holder = nullptr;
-        }
-
-        void runTask(PassOwnPtr<WTF::Function<void(T*, ExecutionContext*)>> task)
-        {
-            ASSERT(executionContext()->isContextThread());
-            if (m_obj)
-                (*task)(m_obj.get(), executionContext());
-        }
-
-    private:
-        // ActiveDOMObject
-        void stop() override
-        {
-            ASSERT(executionContext()->isContextThread());
-            {
-                MutexLocker locker(m_mutex->mutex());
-                if (m_holder)
-                    m_holder->clearInternal();
-                ASSERT(!m_holder);
-            }
-
-            // We have to destruct |*m_obj| here because destructing |*m_obj|
-            // in ~Bridge() might be too late when |executionContext| is
-            // stopped.
-            m_obj.clear();
-        }
-
-
-        OwnPtr<T> m_obj;
-        // All accesses to |m_holder| must be protected by |m_mutex|.
-        RefPtr<MutexWrapper> m_mutex;
-        CrossThreadHolder* m_holder;
-    };
-
-    // Must be protected by |m_mutex|.
-    void clearInternal()
-    {
-        if (m_bridge)
-            m_bridge->clearInternal();
-        m_bridge.clear();
-    }
-
-    CrossThreadHolder(ExecutionContext* executionContext, PassOwnPtr<T> obj)
-        : m_mutex(MutexWrapper::create())
-        , m_bridge(new Bridge(executionContext, obj, m_mutex, this))
-    {
-    }
-
-    RefPtr<MutexWrapper> m_mutex;
-    // |m_bridge| is protected by |m_mutex|.
-    // |m_bridge| is cleared before the thread that allocated |*m_bridge|
-    // is stopped.
-    CrossThreadPersistent<Bridge> m_bridge;
-};
-
 // Object graph:
 //                                           +-------------+
 //                                           |ReaderContext|