text: /*
   * Copyright (C) 2010 Julien Chaffraix <jchaffraix@webkit.org>
   * All right 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
   * OWNER 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.
   */
  
  #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_XMLHTTPREQUEST_XML_HTTP_REQUEST_PROGRESS_EVENT_THROTTLE_H_
  #define THIRD_PARTY_BLINK_RENDERER_CORE_XMLHTTPREQUEST_XML_HTTP_REQUEST_PROGRESS_EVENT_THROTTLE_H_
  
  #include "base/memory/scoped_refptr.h"
  #include "third_party/blink/renderer/platform/heap/handle.h"
  #include "third_party/blink/renderer/platform/heap/prefinalizer.h"
  #include "third_party/blink/renderer/platform/timer.h"
  #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
  #include "third_party/blink/renderer/platform/wtf/forward.h"
  
  namespace blink {
  
  class Event;
  class XMLHttpRequest;
  
  // This class implements the XHR2 ProgressEvent dispatching:
  //   "dispatch a progress event named progress about every 50ms or for every
  //   byte received, whichever is least frequent".
  //
  // readystatechange events also go through this class since ProgressEvents and
  // readystatechange events affect each other.
  //
  // In the comments for this class:
  // - "progress" event means an event named "progress"
  // - ProgressEvent means an event using the ProgressEvent interface defined in
  //   the spec.
  class XMLHttpRequestProgressEventThrottle final
      : public GarbageCollected<XMLHttpRequestProgressEventThrottle>,
        public TimerBase {
    // Need to promptly stop this timer when it is deemed finalizable.
    USING_PRE_FINALIZER(XMLHttpRequestProgressEventThrottle, Stop);
  
   public:
    explicit XMLHttpRequestProgressEventThrottle(XMLHttpRequest*);
    ~XMLHttpRequestProgressEventThrottle() override;
  
    enum DeferredEventAction {
      kIgnore,
      kClear,
      kFlush,
    };
  
    // Dispatches a ProgressEvent.
    //
    // Special treatment for events named "progress" is implemented to dispatch
    // them at the required frequency. If this object is suspended, the given
    // ProgressEvent overwrites the existing. I.e. only the latest one gets
    // queued. If the timer is running, this method just updates
    // m_lengthComputable, m_loaded and m_total. They'll be used on next
    // fired() call.
    // For an event named "progress", a readyStateChange will be dispatched
    // as well.
    void DispatchProgressEvent(const AtomicString&,
                               bool length_computable,
                               uint64_t loaded,
                               uint64_t total);
    // Dispatches the given event after operation about the "progress" event
    // depending on the value of the ProgressEventAction argument.
    void DispatchReadyStateChangeEvent(Event*, DeferredEventAction);
  
    void Trace(Visitor*) const;
  
   private:
    // Dispatches a "progress" progress event and usually a readyStateChange
    // event as well.
    void DispatchProgressProgressEvent(Event*);
  
    // The main purpose of this class is to throttle the "progress"
    // ProgressEvent dispatching. This class represents such a deferred
    // "progress" ProgressEvent.
    class DeferredEvent {
      DISALLOW_NEW();
  
     public:
      DeferredEvent();
      void Set(bool length_computable, uint64_t loaded, uint64_t total);
      void Clear();
      bool IsSet() const { return is_set_; }
      Event* Take();
  
     private:
      uint64_t loaded_;
      uint64_t total_;
      bool length_computable_;
  
      bool is_set_;
    };
  
    void Fired() override;
  
    Member<XMLHttpRequest> target_;
  
    // A slot for the deferred "progress" ProgressEvent. When multiple events
    // arrive, only the last one is stored and others are discarded.
    DeferredEvent deferred_;
  
    // True if any "progress" progress event has been dispatched since
    // |m_target|'s readyState changed.
    bool has_dispatched_progress_progress_event_;
  };
  
  }  // namespace blink
  
  #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_XMLHTTPREQUEST_XML_HTTP_REQUEST_PROGRESS_EVENT_THROTTLE_H_
  