third_party/WebKit/Source/core/workers/WorkerLoaderProxy.h

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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#ifndef WorkerLoaderProxy_h
#define WorkerLoaderProxy_h

#include "core/CoreExport.h"
#include "core/dom/ExecutionContext.h"
#include "wtf/Forward.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/ThreadSafeRefCounted.h"

namespace blink {

// The WorkerLoaderProxy is a proxy to the loader context. Normally, the
// document on the main thread provides loading services for the subordinate
// workers. WorkerLoaderProxy provides 2-way communications to the Document
// context and back to the worker.
//
// Note that in multi-process browsers, the Worker object context and the Document
// context can be distinct.

// The abstract interface providing the methods for actually posting tasks; separated
// from the thread-safe & ref-counted WorkerLoaderProxy object which keeps a protected
// reference to the provider object. This to support non-overlapping lifetimes, the
// provider may be destructed before all references to the WorkerLoaderProxy object
// have been dropped.
//
// A provider implementation must detach itself when finalizing by calling
// WorkerLoaderProxy::detachProvider(). This stops the WorkerLoaderProxy from accessing
// the now-dead object, but it will remain alive while ref-ptrs are still kept to it.
class CORE_EXPORT WorkerLoaderProxyProvider {
public:
    virtual ~WorkerLoaderProxyProvider() { }

    // Posts a task to the thread which runs the loading code (normally, the main thread).
    virtual void postTaskToLoader(PassOwnPtr<ExecutionContextTask>) = 0;

    // Posts callbacks from loading code to the WorkerGlobalScope.
    // Returns true if the task was posted successfully.
    virtual bool postTaskToWorkerGlobalScope(PassOwnPtr<ExecutionContextTask>) = 0;
};

class CORE_EXPORT WorkerLoaderProxy : public ThreadSafeRefCounted<WorkerLoaderProxy>, public WorkerLoaderProxyProvider {
public:
    static PassRefPtr<WorkerLoaderProxy> create(WorkerLoaderProxyProvider* loaderProxyProvider)
    {
        return adoptRef(new WorkerLoaderProxy(loaderProxyProvider));
    }

    ~WorkerLoaderProxy() override;

    void postTaskToLoader(PassOwnPtr<ExecutionContextTask>) override;
    bool postTaskToWorkerGlobalScope(PassOwnPtr<ExecutionContextTask>) override;

    // Notification from the provider that it can no longer be
    // accessed. An implementation of WorkerLoaderProxyProvider is
    // required to call detachProvider() when finalizing.
    void detachProvider(WorkerLoaderProxyProvider*);

private:
    explicit WorkerLoaderProxy(WorkerLoaderProxyProvider*);

    Mutex m_lock;
    WorkerLoaderProxyProvider* m_loaderProxyProvider;
};

} // namespace blink

#endif // WorkerLoaderProxy_h