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      1 /*
      2  * Copyright (C) 2010 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef WorkerFileWriterCallbacksBridge_h
     32 #define WorkerFileWriterCallbacksBridge_h
     33 
     34 #if ENABLE(FILE_SYSTEM)
     35 
     36 #include "WebFileError.h"
     37 #include "WebFileWriterClient.h"
     38 #include "WorkerContext.h"
     39 #include <wtf/PassOwnPtr.h>
     40 #include <wtf/PassRefPtr.h>
     41 #include <wtf/ThreadSafeRefCounted.h>
     42 
     43 namespace WebCore {
     44     class AsyncFileWriterClient;
     45     class KURL;
     46     class WorkerLoaderProxy;
     47 }
     48 
     49 namespace WTF {
     50     class String;
     51 }
     52 using WTF::String;
     53 
     54 namespace WebKit {
     55 
     56 class WebFileSystem;
     57 class WebFileWriter;
     58 class WebFileWriterClient;
     59 class WebWorkerBase;
     60 
     61 // This class is used as a mechanism to bridge calls between threads.
     62 // Calls to a WebFileWriter must happen on the main thread, but they come from
     63 // the context thread. The responses through the WebFileWriterClient interface
     64 // start on the main thread, but must be sent via the worker context thread.
     65 //
     66 // A typical flow for write would look like this:
     67 // Bridge::postWriteToMainThread() on WorkerThread
     68 //  --> Bridge::writeOnMainThread() is called on MainThread
     69 //  --> WebFileWriter::write()
     70 //      This makes an IPC; the actual operation is down in the browser.
     71 //  --> Bridge::didWrite is called on MainThread
     72 //  --> Bridge::didWriteOnWorkerThread is called on WorkerThread
     73 //      This calls the original client (m_clientOnWorkerThread).
     74 //
     75 // The bridge object is refcounted, so that it doesn't get deleted while there
     76 // are cross-thread calls in flight. Each CrossThreadTask carries a reference
     77 // to the bridge, which guarantees that the bridge will still be valid when the
     78 // task is executed. In order to shut down the bridge, the WebFileWriterClient
     79 // should call postShutdownToMainThread before dropping its reference to the
     80 // bridge. This ensures that the WebFileWriter will be cleared on the main
     81 // thread and that no further calls to the WebFileWriterClient will be made.
     82 class WorkerFileWriterCallbacksBridge : public ThreadSafeRefCounted<WorkerFileWriterCallbacksBridge>, public WebCore::WorkerContext::Observer, public WebFileWriterClient {
     83 public:
     84     ~WorkerFileWriterCallbacksBridge();
     85 
     86     // WorkerContext::Observer method.
     87     virtual void notifyStop();
     88 
     89     static PassRefPtr<WorkerFileWriterCallbacksBridge> create(const String& path, WebCore::WorkerLoaderProxy* proxy, WebCore::ScriptExecutionContext* workerContext, WebCore::AsyncFileWriterClient* client)
     90     {
     91         return adoptRef(new WorkerFileWriterCallbacksBridge(path, proxy, workerContext, client));
     92     }
     93 
     94     // Methods that create an instance and post an initial request task to the main thread. They must be called on the worker thread.
     95     void postWriteToMainThread(long long position, const WebCore::KURL& data);
     96     void postTruncateToMainThread(long long length);
     97     void postAbortToMainThread();
     98 
     99     // The owning WorkerAsyncFileWriterChromium should call this method before dropping its last reference to the bridge, on the context thread.
    100     // The actual deletion of the WorkerFileWriterCallbacksBridge may happen on either the main or context thread, depending on where the last reference goes away; that's safe as long as this is called first.
    101     void postShutdownToMainThread(PassRefPtr<WorkerFileWriterCallbacksBridge>);
    102 
    103     // Callback methods that are called on the main thread.
    104     // These are the implementation of WebKit::WebFileWriterClient.
    105     void didWrite(long long bytes, bool complete);
    106     void didFail(WebFileError);
    107     void didTruncate();
    108 
    109     // Call this on the context thread to wait for the current operation to complete.
    110     bool waitForOperationToComplete();
    111 
    112 private:
    113     WorkerFileWriterCallbacksBridge(const String& path, WebCore::WorkerLoaderProxy*, WebCore::ScriptExecutionContext*, WebCore::AsyncFileWriterClient*);
    114 
    115     void postInitToMainThread(const String& path);
    116 
    117     // Methods that are to be called on the main thread.
    118     static void writeOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long position, const WebCore::KURL& data);
    119     static void truncateOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long length);
    120     static void abortOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
    121     static void initOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, const String& path);
    122     static void shutdownOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
    123 
    124     // Methods that dispatch to AsyncFileWriterClient on the worker threads.
    125     static void didWriteOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, long long length, bool complete);
    126     static void didFailOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, WebFileError);
    127     static void didTruncateOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>);
    128 
    129     // Called on the main thread to run the supplied task.
    130     static void runTaskOnMainThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
    131     // Called on the worker thread to run the supplied task.
    132     static void runTaskOnWorkerThread(WebCore::ScriptExecutionContext*, PassRefPtr<WorkerFileWriterCallbacksBridge>, PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
    133 
    134     // Called on the worker thread to dispatch to the main thread.
    135     void dispatchTaskToMainThread(PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
    136     // Called on the main thread to dispatch to the worker thread.
    137     void dispatchTaskToWorkerThread(PassOwnPtr<WebCore::ScriptExecutionContext::Task>);
    138 
    139     // Used from the main thread to post tasks to the context thread.
    140     WebCore::WorkerLoaderProxy* m_proxy;
    141 
    142     // Used on the context thread, only to check that we're running on the context thread.
    143     WebCore::ScriptExecutionContext* m_workerContext;
    144 
    145     // Created and destroyed from the main thread.
    146     OwnPtr<WebKit::WebFileWriter> m_writer;
    147 
    148     // Used on the context thread to call back into the client.
    149     WebCore::AsyncFileWriterClient* m_clientOnWorkerThread;
    150 
    151     // Used to indicate that shutdown has started on the main thread, and hence the writer has been deleted.
    152     bool m_writerDeleted;
    153 
    154     // Used by waitForOperationToComplete.
    155     bool m_operationInProgress;
    156 
    157     // Used by postTaskForModeToWorkerContext and runInMode.
    158     String m_mode;
    159 };
    160 
    161 } // namespace WebCore
    162 
    163 #endif
    164 
    165 #endif // WorkerFileWriterCallbacksBridge_h
    166