зеркало из https://github.com/mozilla/pjs.git
480 строки
19 KiB
C++
480 строки
19 KiB
C++
/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#if !defined(MediaResource_h_)
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#define MediaResource_h_
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#include "mozilla/Mutex.h"
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#include "mozilla/XPCOM.h"
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#include "nsIChannel.h"
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#include "nsIPrincipal.h"
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#include "nsIURI.h"
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#include "nsIStreamListener.h"
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#include "nsIChannelEventSink.h"
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#include "nsIInterfaceRequestor.h"
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#include "nsMediaCache.h"
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// For HTTP seeking, if number of bytes needing to be
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// seeked forward is less than this value then a read is
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// done rather than a byte range request.
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static const PRInt64 SEEK_VS_READ_THRESHOLD = 32*1024;
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static const PRUint32 HTTP_REQUESTED_RANGE_NOT_SATISFIABLE_CODE = 416;
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class nsMediaDecoder;
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namespace mozilla {
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/**
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* This class is useful for estimating rates of data passing through
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* some channel. The idea is that activity on the channel "starts"
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* and "stops" over time. At certain times data passes through the
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* channel (usually while the channel is active; data passing through
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* an inactive channel is ignored). The GetRate() function computes
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* an estimate of the "current rate" of the channel, which is some
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* kind of average of the data passing through over the time the
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* channel is active.
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*
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* All methods take "now" as a parameter so the user of this class can
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* control the timeline used.
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*/
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class MediaChannelStatistics {
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public:
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MediaChannelStatistics() { Reset(); }
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void Reset() {
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mLastStartTime = TimeStamp();
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mAccumulatedTime = TimeDuration(0);
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mAccumulatedBytes = 0;
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mIsStarted = false;
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}
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void Start(TimeStamp aNow) {
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if (mIsStarted)
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return;
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mLastStartTime = aNow;
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mIsStarted = true;
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}
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void Stop(TimeStamp aNow) {
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if (!mIsStarted)
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return;
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mAccumulatedTime += aNow - mLastStartTime;
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mIsStarted = false;
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}
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void AddBytes(PRInt64 aBytes) {
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if (!mIsStarted) {
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// ignore this data, it may be related to seeking or some other
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// operation we don't care about
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return;
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}
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mAccumulatedBytes += aBytes;
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}
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double GetRateAtLastStop(bool* aReliable) {
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double seconds = mAccumulatedTime.ToSeconds();
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*aReliable = seconds >= 1.0;
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if (seconds <= 0.0)
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return 0.0;
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return static_cast<double>(mAccumulatedBytes)/seconds;
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}
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double GetRate(TimeStamp aNow, bool* aReliable) {
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TimeDuration time = mAccumulatedTime;
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if (mIsStarted) {
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time += aNow - mLastStartTime;
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}
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double seconds = time.ToSeconds();
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*aReliable = seconds >= 3.0;
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if (seconds <= 0.0)
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return 0.0;
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return static_cast<double>(mAccumulatedBytes)/seconds;
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}
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private:
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PRInt64 mAccumulatedBytes;
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TimeDuration mAccumulatedTime;
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TimeStamp mLastStartTime;
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bool mIsStarted;
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};
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// Represents a section of contiguous media, with a start and end offset.
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// Used to denote ranges of data which are cached.
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class MediaByteRange {
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public:
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MediaByteRange() : mStart(0), mEnd(0) {}
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MediaByteRange(PRInt64 aStart, PRInt64 aEnd)
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: mStart(aStart), mEnd(aEnd)
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{
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NS_ASSERTION(mStart < mEnd, "Range should end after start!");
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}
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bool IsNull() const {
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return mStart == 0 && mEnd == 0;
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}
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PRInt64 mStart, mEnd;
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};
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/**
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* Provides a thread-safe, seek/read interface to resources
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* loaded from a URI. Uses nsMediaCache to cache data received over
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* Necko's async channel API, thus resolving the mismatch between clients
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* that need efficient random access to the data and protocols that do not
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* support efficient random access, such as HTTP.
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*
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* Instances of this class must be created on the main thread.
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* Most methods must be called on the main thread only. Read, Seek and
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* Tell must only be called on non-main threads. In the case of the Ogg
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* Decoder they are called on the Decode thread for example. You must
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* ensure that no threads are calling these methods once Close is called.
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*
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* Instances of this class are explicitly managed. 'delete' it when done.
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*
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* The generic implementation of this class is ChannelMediaResource, which can
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* handle any URI for which Necko supports AsyncOpen.
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* The 'file:' protocol can be implemented efficiently with direct random
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* access, so the FileMediaResource implementation class bypasses the cache.
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* MediaResource::Create automatically chooses the best implementation class.
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*/
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class MediaResource
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{
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public:
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virtual ~MediaResource()
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{
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MOZ_COUNT_DTOR(MediaResource);
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}
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// The following can be called on the main thread only:
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// Get the URI
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nsIURI* URI() const { return mURI; }
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// Close the resource, stop any listeners, channels, etc.
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// Cancels any currently blocking Read request and forces that request to
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// return an error.
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virtual nsresult Close() = 0;
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// Suspend any downloads that are in progress.
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// If aCloseImmediately is set, resources should be released immediately
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// since we don't expect to resume again any time soon. Otherwise we
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// may resume again soon so resources should be held for a little
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// while.
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virtual void Suspend(bool aCloseImmediately) = 0;
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// Resume any downloads that have been suspended.
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virtual void Resume() = 0;
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// Get the current principal for the channel
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virtual already_AddRefed<nsIPrincipal> GetCurrentPrincipal() = 0;
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// If this returns false, then we shouldn't try to clone this MediaResource
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// because its underlying resources are not suitable for reuse (e.g.
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// because the underlying connection has been lost, or this resource
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// just can't be safely cloned). If this returns true, CloneData could
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// still fail. If this returns false, CloneData should not be called.
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virtual bool CanClone() { return false; }
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// Create a new stream of the same type that refers to the same URI
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// with a new channel. Any cached data associated with the original
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// stream should be accessible in the new stream too.
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virtual MediaResource* CloneData(nsMediaDecoder* aDecoder) = 0;
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// These methods are called off the main thread.
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// The mode is initially MODE_PLAYBACK.
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virtual void SetReadMode(nsMediaCacheStream::ReadMode aMode) = 0;
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// This is the client's estimate of the playback rate assuming
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// the media plays continuously. The cache can't guess this itself
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// because it doesn't know when the decoder was paused, buffering, etc.
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virtual void SetPlaybackRate(PRUint32 aBytesPerSecond) = 0;
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// Read up to aCount bytes from the stream. The buffer must have
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// enough room for at least aCount bytes. Stores the number of
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// actual bytes read in aBytes (0 on end of file).
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// May read less than aCount bytes if the number of
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// available bytes is less than aCount. Always check *aBytes after
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// read, and call again if necessary.
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virtual nsresult Read(char* aBuffer, PRUint32 aCount, PRUint32* aBytes) = 0;
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// Seek to the given bytes offset in the stream. aWhence can be
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// one of:
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// NS_SEEK_SET
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// NS_SEEK_CUR
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// NS_SEEK_END
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//
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// In the Http strategy case the cancel will cause the http
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// channel's listener to close the pipe, forcing an i/o error on any
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// blocked read. This will allow the decode thread to complete the
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// event.
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//
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// In the case of a seek in progress, the byte range request creates
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// a new listener. This is done on the main thread via seek
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// synchronously dispatching an event. This avoids the issue of us
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// closing the listener but an outstanding byte range request
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// creating a new one. They run on the same thread so no explicit
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// synchronisation is required. The byte range request checks for
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// the cancel flag and does not create a new channel or listener if
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// we are cancelling.
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//
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// The default strategy does not do any seeking - the only issue is
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// a blocked read which it handles by causing the listener to close
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// the pipe, as per the http case.
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//
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// The file strategy doesn't block for any great length of time so
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// is fine for a no-op cancel.
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virtual nsresult Seek(PRInt32 aWhence, PRInt64 aOffset) = 0;
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// Report the current offset in bytes from the start of the stream.
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virtual PRInt64 Tell() = 0;
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// Moves any existing channel loads into the background, so that they don't
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// block the load event. Any new loads initiated (for example to seek)
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// will also be in the background.
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void MoveLoadsToBackground();
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// Ensures that the value returned by IsSuspendedByCache below is up to date
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// (i.e. the cache has examined this stream at least once).
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virtual void EnsureCacheUpToDate() {}
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// These can be called on any thread.
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// Cached blocks associated with this stream will not be evicted
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// while the stream is pinned.
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virtual void Pin() = 0;
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virtual void Unpin() = 0;
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// Get the estimated download rate in bytes per second (assuming no
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// pausing of the channel is requested by Gecko).
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// *aIsReliable is set to true if we think the estimate is useful.
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virtual double GetDownloadRate(bool* aIsReliable) = 0;
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// Get the length of the stream in bytes. Returns -1 if not known.
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// This can change over time; after a seek operation, a misbehaving
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// server may give us a resource of a different length to what it had
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// reported previously --- or it may just lie in its Content-Length
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// header and give us more or less data than it reported. We will adjust
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// the result of GetLength to reflect the data that's actually arriving.
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virtual PRInt64 GetLength() = 0;
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// Returns the offset of the first byte of cached data at or after aOffset,
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// or -1 if there is no such cached data.
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virtual PRInt64 GetNextCachedData(PRInt64 aOffset) = 0;
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// Returns the end of the bytes starting at the given offset
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// which are in cache.
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virtual PRInt64 GetCachedDataEnd(PRInt64 aOffset) = 0;
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// Returns true if all the data from aOffset to the end of the stream
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// is in cache. If the end of the stream is not known, we return false.
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virtual bool IsDataCachedToEndOfResource(PRInt64 aOffset) = 0;
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// Returns true if this stream is suspended by the cache because the
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// cache is full. If true then the decoder should try to start consuming
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// data, otherwise we may not be able to make progress.
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// nsMediaDecoder::NotifySuspendedStatusChanged is called when this
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// changes.
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// For resources using the media cache, this returns true only when all
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// streams for the same resource are all suspended.
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// If aActiveResource is non-null, fills it with a pointer to a stream
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// for this resource that is not suspended or ended.
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virtual bool IsSuspendedByCache(MediaResource** aActiveResource) = 0;
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// Returns true if this stream has been suspended.
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virtual bool IsSuspended() = 0;
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// Reads only data which is cached in the media cache. If you try to read
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// any data which overlaps uncached data, or if aCount bytes otherwise can't
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// be read, this function will return failure. This function be called from
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// any thread, and it is the only read operation which is safe to call on
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// the main thread, since it's guaranteed to be non blocking.
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virtual nsresult ReadFromCache(char* aBuffer,
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PRInt64 aOffset,
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PRUint32 aCount) = 0;
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/**
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* Create a resource, reading data from the channel. Call on main thread only.
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* The caller must follow up by calling resource->Open().
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*/
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static MediaResource* Create(nsMediaDecoder* aDecoder, nsIChannel* aChannel);
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/**
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* Open the stream. This creates a stream listener and returns it in
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* aStreamListener; this listener needs to be notified of incoming data.
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*/
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virtual nsresult Open(nsIStreamListener** aStreamListener) = 0;
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/**
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* Fills aRanges with MediaByteRanges representing the data which is cached
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* in the media cache. Stream should be pinned during call and while
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* aRanges is being used.
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*/
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virtual nsresult GetCachedRanges(nsTArray<MediaByteRange>& aRanges) = 0;
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protected:
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MediaResource(nsMediaDecoder* aDecoder, nsIChannel* aChannel, nsIURI* aURI) :
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mDecoder(aDecoder),
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mChannel(aChannel),
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mURI(aURI),
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mLoadInBackground(false)
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{
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MOZ_COUNT_CTOR(MediaResource);
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}
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// Set the request's load flags to aFlags. If the request is part of a
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// load group, the request is removed from the group, the flags are set, and
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// then the request is added back to the load group.
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void ModifyLoadFlags(nsLoadFlags aFlags);
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// This is not an nsCOMPointer to prevent a circular reference
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// between the decoder to the media stream object. The stream never
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// outlives the lifetime of the decoder.
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nsMediaDecoder* mDecoder;
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// Channel used to download the media data. Must be accessed
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// from the main thread only.
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nsCOMPtr<nsIChannel> mChannel;
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// URI in case the stream needs to be re-opened. Access from
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// main thread only.
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nsCOMPtr<nsIURI> mURI;
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// True if MoveLoadsToBackground() has been called, i.e. the load event
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// has been fired, and all channel loads will be in the background.
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bool mLoadInBackground;
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};
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/**
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* This is the MediaResource implementation that wraps Necko channels.
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* Much of its functionality is actually delegated to nsMediaCache via
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* an underlying nsMediaCacheStream.
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*
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* All synchronization is performed by nsMediaCacheStream; all off-main-
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* thread operations are delegated directly to that object.
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*/
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class ChannelMediaResource : public MediaResource
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{
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public:
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ChannelMediaResource(nsMediaDecoder* aDecoder, nsIChannel* aChannel, nsIURI* aURI);
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~ChannelMediaResource();
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// These are called on the main thread by nsMediaCache. These must
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// not block or grab locks, because the media cache is holding its lock.
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// Notify that data is available from the cache. This can happen even
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// if this stream didn't read any data, since another stream might have
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// received data for the same resource.
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void CacheClientNotifyDataReceived();
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// Notify that we reached the end of the stream. This can happen even
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// if this stream didn't read any data, since another stream might have
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// received data for the same resource.
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void CacheClientNotifyDataEnded(nsresult aStatus);
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// Notify that the principal for the cached resource changed.
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void CacheClientNotifyPrincipalChanged();
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// These are called on the main thread by nsMediaCache. These shouldn't block,
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// but they may grab locks --- the media cache is not holding its lock
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// when these are called.
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// Start a new load at the given aOffset. The old load is cancelled
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// and no more data from the old load will be notified via
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// nsMediaCacheStream::NotifyDataReceived/Ended.
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// This can fail.
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nsresult CacheClientSeek(PRInt64 aOffset, bool aResume);
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// Suspend the current load since data is currently not wanted
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nsresult CacheClientSuspend();
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// Resume the current load since data is wanted again
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nsresult CacheClientResume();
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// Main thread
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virtual nsresult Open(nsIStreamListener** aStreamListener);
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virtual nsresult Close();
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virtual void Suspend(bool aCloseImmediately);
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virtual void Resume();
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virtual already_AddRefed<nsIPrincipal> GetCurrentPrincipal();
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// Return true if the stream has been closed.
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bool IsClosed() const { return mCacheStream.IsClosed(); }
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virtual bool CanClone();
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virtual MediaResource* CloneData(nsMediaDecoder* aDecoder);
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virtual nsresult ReadFromCache(char* aBuffer, PRInt64 aOffset, PRUint32 aCount);
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virtual void EnsureCacheUpToDate();
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// Other thread
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virtual void SetReadMode(nsMediaCacheStream::ReadMode aMode);
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virtual void SetPlaybackRate(PRUint32 aBytesPerSecond);
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virtual nsresult Read(char* aBuffer, PRUint32 aCount, PRUint32* aBytes);
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virtual nsresult Seek(PRInt32 aWhence, PRInt64 aOffset);
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virtual PRInt64 Tell();
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// Any thread
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virtual void Pin();
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virtual void Unpin();
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virtual double GetDownloadRate(bool* aIsReliable);
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virtual PRInt64 GetLength();
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virtual PRInt64 GetNextCachedData(PRInt64 aOffset);
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virtual PRInt64 GetCachedDataEnd(PRInt64 aOffset);
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virtual bool IsDataCachedToEndOfResource(PRInt64 aOffset);
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virtual bool IsSuspendedByCache(MediaResource** aActiveResource);
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virtual bool IsSuspended();
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class Listener : public nsIStreamListener,
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public nsIInterfaceRequestor,
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public nsIChannelEventSink
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{
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public:
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Listener(ChannelMediaResource* aResource) : mResource(aResource) {}
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NS_DECL_ISUPPORTS
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NS_DECL_NSIREQUESTOBSERVER
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NS_DECL_NSISTREAMLISTENER
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NS_DECL_NSICHANNELEVENTSINK
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NS_DECL_NSIINTERFACEREQUESTOR
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void Revoke() { mResource = nsnull; }
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private:
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ChannelMediaResource* mResource;
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};
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friend class Listener;
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nsresult GetCachedRanges(nsTArray<MediaByteRange>& aRanges);
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protected:
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// These are called on the main thread by Listener.
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nsresult OnStartRequest(nsIRequest* aRequest);
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nsresult OnStopRequest(nsIRequest* aRequest, nsresult aStatus);
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nsresult OnDataAvailable(nsIRequest* aRequest,
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nsIInputStream* aStream,
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PRUint32 aCount);
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nsresult OnChannelRedirect(nsIChannel* aOld, nsIChannel* aNew, PRUint32 aFlags);
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// Opens the channel, using an HTTP byte range request to start at mOffset
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// if possible. Main thread only.
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nsresult OpenChannel(nsIStreamListener** aStreamListener);
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nsresult RecreateChannel();
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// Add headers to HTTP request. Main thread only.
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void SetupChannelHeaders();
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// Closes the channel. Main thread only.
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void CloseChannel();
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void DoNotifyDataReceived();
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static NS_METHOD CopySegmentToCache(nsIInputStream *aInStream,
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void *aClosure,
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const char *aFromSegment,
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PRUint32 aToOffset,
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PRUint32 aCount,
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PRUint32 *aWriteCount);
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// Suspend the channel only if the channels is currently downloading data.
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// If it isn't we set a flag, mIgnoreResume, so that PossiblyResume knows
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// whether to acutually resume or not.
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void PossiblySuspend();
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// Resume from a suspend if we actually suspended (See PossiblySuspend).
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void PossiblyResume();
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// Main thread access only
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PRInt64 mOffset;
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nsRefPtr<Listener> mListener;
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// A data received event for the decoder that has been dispatched but has
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// not yet been processed.
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nsRevocableEventPtr<nsRunnableMethod<ChannelMediaResource, void, false> > mDataReceivedEvent;
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PRUint32 mSuspendCount;
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// When this flag is set, if we get a network error we should silently
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// reopen the stream.
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bool mReopenOnError;
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// When this flag is set, we should not report the next close of the
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// channel.
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bool mIgnoreClose;
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// Any thread access
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nsMediaCacheStream mCacheStream;
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// This lock protects mChannelStatistics
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Mutex mLock;
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MediaChannelStatistics mChannelStatistics;
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// True if we couldn't suspend the stream and we therefore don't want
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// to resume later. This is usually due to the channel not being in the
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// isPending state at the time of the suspend request.
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bool mIgnoreResume;
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};
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}
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#endif
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