src/com/android/tv/tuner/exoplayer/buffer/SampleChunk.java - platform/packages/apps/TV - Git at Google

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.tv.tuner.exoplayer.buffer;

 import android.support.annotation.Nullable;
 import android.support.annotation.VisibleForTesting;
 import android.util.Log;

 import com.google.android.exoplayer.SampleHolder;

 import java.io.File;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.channels.FileChannel;

 /**
  * {@link SampleChunk} stores samples into file and makes them available for read.
  * Stored file = { Header, Sample } * N
  * Header = sample size : int, sample flag : int, sample PTS in micro second : long
  */
 public class SampleChunk {
     private static final String TAG = "SampleChunk";
     private static final boolean DEBUG = false;

     private final long mCreatedTimeMs;
     private final long mStartPositionUs;
     private SampleChunk mNextChunk;

     // Header = sample size : int, sample flag : int, sample PTS in micro second : long
     private static final int SAMPLE_HEADER_LENGTH = 16;

     private final File mFile;
     private final ChunkCallback mChunkCallback;
     private final SamplePool mSamplePool;
     private RandomAccessFile mAccessFile;
     private long mWriteOffset;
     private boolean mWriteFinished;
     private boolean mIsReading;
     private boolean mIsWriting;

     /**
      * A callback for chunks being committed to permanent storage.
      */
     public static abstract class ChunkCallback {

         /**
          * Notifies when writing a SampleChunk is completed.
          *
          * @param chunk SampleChunk which is written completely
          */
         public void onChunkWrite(SampleChunk chunk) {

         }

         /**
          * Notifies when a SampleChunk is deleted.
          *
          * @param chunk SampleChunk which is deleted from storage
          */
         public void onChunkDelete(SampleChunk chunk) {
         }
     }

     /**
      * A class for SampleChunk creation.
      */
     public static class SampleChunkCreator {

         /**
          * Returns a newly created SampleChunk to read & write samples.
          *
          * @param samplePool sample allocator
          * @param file filename which will be created newly
          * @param startPositionUs the start position of the earliest sample to be stored
          * @param chunkCallback for total storage usage change notification
          */
         SampleChunk createSampleChunk(SamplePool samplePool, File file,
                 long startPositionUs, ChunkCallback chunkCallback) {
             return new SampleChunk(samplePool, file, startPositionUs, System.currentTimeMillis(),
                     chunkCallback);
         }

         /**
          * Returns a newly created SampleChunk which is backed by an existing file.
          * Created SampleChunk is read-only.
          *
          * @param samplePool sample allocator
          * @param bufferDir the directory where the file to read is located
          * @param filename the filename which will be read afterwards
          * @param startPositionUs the start position of the earliest sample in the file
          * @param chunkCallback for total storage usage change notification
          * @param prev the previous SampleChunk just before the newly created SampleChunk
          * @throws IOException
          */
         SampleChunk loadSampleChunkFromFile(SamplePool samplePool, File bufferDir,
                 String filename, long startPositionUs, ChunkCallback chunkCallback,
                 SampleChunk prev) throws IOException {
             File file = new File(bufferDir, filename);
             SampleChunk chunk =
                     new SampleChunk(samplePool, file, startPositionUs, chunkCallback);
             if (prev != null) {
                 prev.mNextChunk = chunk;
             }
             return chunk;
         }
     }

     /**
      * Handles I/O for SampleChunk.
      * Maintains current SampleChunk and the current offset for next I/O operation.
      */
     static class IoState {
         private SampleChunk mChunk;
         private long mCurrentOffset;

         private boolean equals(SampleChunk chunk, long offset) {
             return chunk == mChunk && mCurrentOffset == offset;
         }

         /**
          * Returns whether read I/O operation is finished.
          */
         boolean isReadFinished() {
             return mChunk == null;
         }

         /**
          * Returns the start position of the current SampleChunk
          */
         long getStartPositionUs() {
             return mChunk == null ? 0 : mChunk.getStartPositionUs();
         }

         private void reset(@Nullable SampleChunk chunk) {
             mChunk = chunk;
             mCurrentOffset = 0;
         }

         private void reset(SampleChunk chunk, long offset) {
             mChunk = chunk;
             mCurrentOffset = offset;
         }

         /**
          * Prepares for read I/O operation from a new SampleChunk.
          *
          * @param chunk the new SampleChunk to read from
          * @throws IOException
          */
         void openRead(SampleChunk chunk, long offset) throws IOException {
             if (mChunk != null) {
                 mChunk.closeRead();
             }
             chunk.openRead();
             reset(chunk, offset);
         }

         /**
          * Prepares for write I/O operation to a new SampleChunk.
          *
          * @param chunk the new SampleChunk to write samples afterwards
          * @throws IOException
          */
         void openWrite(SampleChunk chunk) throws IOException{
             if (mChunk != null) {
                 mChunk.closeWrite(chunk);
             }
             chunk.openWrite();
             reset(chunk);
         }

         /**
          * Reads a sample if it is available.
          *
          * @return Returns a sample if it is available, null otherwise.
          * @throws IOException
          */
         SampleHolder read() throws IOException {
             if (mChunk != null && mChunk.isReadFinished(this)) {
                 SampleChunk next = mChunk.mNextChunk;
                 mChunk.closeRead();
                 if (next != null) {
                     next.openRead();
                 }
                 reset(next);
             }
             if (mChunk != null) {
                 try {
                     return mChunk.read(this);
                 } catch (IllegalStateException e) {
                     // Write is finished and there is no additional buffer to read.
                     Log.w(TAG, "Tried to read sample over EOS.");
                     return null;
                 }
             } else {
                 return null;
             }
         }

         /**
          * Writes a sample.
          *
          * @param sample to write
          * @param nextChunk if this is {@code null} writes at the current SampleChunk,
          *             otherwise close current SampleChunk and writes at this
          * @throws IOException
          */
         void write(SampleHolder sample, SampleChunk nextChunk)
                 throws IOException {
             if (nextChunk != null) {
                 if (mChunk == null || mChunk.mNextChunk != null) {
                     throw new IllegalStateException("Requested write for wrong SampleChunk");
                 }
                 mChunk.closeWrite(nextChunk);
                 mChunk.mChunkCallback.onChunkWrite(mChunk);
                 nextChunk.openWrite();
                 reset(nextChunk);
             }
             mChunk.write(sample, this);
         }

         /**
          * Finishes write I/O operation.
          *
          * @throws IOException
          */
         void closeWrite() throws IOException {
             if (mChunk != null) {
                 mChunk.closeWrite(null);
             }
         }

         /**
          * Returns the current SampleChunk for subsequent I/O operation.
          */
         SampleChunk getChunk() {
             return mChunk;
         }

         /**
          * Returns the current offset of the current SampleChunk for subsequent I/O operation.
          */
         long getOffset() {
             return mCurrentOffset;
         }

         /**
          * Releases SampleChunk. the SampleChunk will not be used anymore.
          *
          * @param chunk to release
          * @param delete {@code true} when the backed file needs to be deleted,
          *        {@code false} otherwise.
          */
         static void release(SampleChunk chunk, boolean delete) {
             chunk.release(delete);
         }
     }

     @VisibleForTesting
     protected SampleChunk(SamplePool samplePool, File file, long startPositionUs,
             long createdTimeMs, ChunkCallback chunkCallback) {
         mStartPositionUs = startPositionUs;
         mCreatedTimeMs = createdTimeMs;
         mSamplePool = samplePool;
         mFile = file;
         mChunkCallback = chunkCallback;
     }

     // Constructor of SampleChunk which is backed by the given existing file.
     private SampleChunk(SamplePool samplePool, File file, long startPositionUs,
             ChunkCallback chunkCallback) throws IOException {
         mStartPositionUs = startPositionUs;
         mCreatedTimeMs = mStartPositionUs / 1000;
         mSamplePool = samplePool;
         mFile = file;
         mChunkCallback = chunkCallback;
         mWriteFinished = true;
     }

     private void openRead() throws IOException {
         if (!mIsReading) {
             if (mAccessFile == null) {
                 mAccessFile = new RandomAccessFile(mFile, "r");
             }
             if (mWriteFinished && mWriteOffset == 0) {
                 // Lazy loading of write offset, in order not to load
                 // all SampleChunk's write offset at start time of recorded playback.
                 mWriteOffset = mAccessFile.length();
             }
             mIsReading = true;
         }
     }

     private void openWrite() throws IOException {
         if (mWriteFinished) {
             throw new IllegalStateException("Opened for write though write is already finished");
         }
         if (!mIsWriting) {
             if (mIsReading) {
                 throw new IllegalStateException("Write is requested for "
                         + "an already opened SampleChunk");
             }
             mAccessFile = new RandomAccessFile(mFile, "rw");
             mIsWriting = true;
         }
     }

     private void CloseAccessFileIfNeeded() throws IOException {
         if (!mIsReading && !mIsWriting) {
             try {
                 if (mAccessFile != null) {
                     mAccessFile.close();
                 }
             } finally {
                 mAccessFile = null;
             }
         }
     }

     private void closeRead() throws IOException{
         if (mIsReading) {
             mIsReading = false;
             CloseAccessFileIfNeeded();
         }
     }

     private void closeWrite(SampleChunk nextChunk)
             throws IOException {
         if (mIsWriting) {
             mNextChunk = nextChunk;
             mIsWriting = false;
             mWriteFinished = true;
             CloseAccessFileIfNeeded();
         }
     }

     private boolean isReadFinished(IoState state) {
         return mWriteFinished && state.equals(this, mWriteOffset);
     }

     private SampleHolder read(IoState state) throws IOException {
         if (mAccessFile == null || state.mChunk != this) {
             throw new IllegalStateException("Requested read for wrong SampleChunk");
         }
         long offset = state.mCurrentOffset;
         if (offset >= mWriteOffset) {
             if (mWriteFinished) {
                 throw new IllegalStateException("Requested read for wrong range");
             } else {
                 if (offset != mWriteOffset) {
                     Log.e(TAG, "This should not happen!");
                 }
                 return null;
             }
         }
         mAccessFile.seek(offset);
         int size = mAccessFile.readInt();
         SampleHolder sample = mSamplePool.acquireSample(size);
         sample.size = size;
         sample.flags = mAccessFile.readInt();
         sample.timeUs = mAccessFile.readLong();
         sample.clearData();
         sample.data.put(mAccessFile.getChannel().map(FileChannel.MapMode.READ_ONLY,
                 offset + SAMPLE_HEADER_LENGTH, sample.size));
         offset += sample.size + SAMPLE_HEADER_LENGTH;
         state.mCurrentOffset = offset;
         return sample;
     }

     @VisibleForTesting
     protected void write(SampleHolder sample, IoState state)
             throws IOException {
         if (mAccessFile == null || mNextChunk != null || !state.equals(this, mWriteOffset)) {
             throw new IllegalStateException("Requested write for wrong SampleChunk");
         }

         mAccessFile.seek(mWriteOffset);
         mAccessFile.writeInt(sample.size);
         mAccessFile.writeInt(sample.flags);
         mAccessFile.writeLong(sample.timeUs);
         sample.data.position(0).limit(sample.size);
         mAccessFile.getChannel().position(mWriteOffset + SAMPLE_HEADER_LENGTH).write(sample.data);
         mWriteOffset += sample.size + SAMPLE_HEADER_LENGTH;
         state.mCurrentOffset = mWriteOffset;
     }

     private void release(boolean delete) {
         mWriteFinished = true;
         mIsReading = mIsWriting = false;
         try {
             if (mAccessFile != null) {
                 mAccessFile.close();
             }
         } catch (IOException e) {
             // Since the SampleChunk will not be reused, ignore exception.
         }
         if (delete) {
             mFile.delete();
             mChunkCallback.onChunkDelete(this);
         }
     }

     /**
      * Returns the start position.
      */
     public long getStartPositionUs() {
         return mStartPositionUs;
     }

     /**
      * Returns the creation time.
      */
     public long getCreatedTimeMs() {
         return mCreatedTimeMs;
     }

     /**
      * Returns the current size.
      */
     public long getSize() {
         return mWriteOffset;
     }
 }
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.tv.tuner.exoplayer.buffer;

	import android.support.annotation.Nullable;
	import android.support.annotation.VisibleForTesting;
	import android.util.Log;

	import com.google.android.exoplayer.SampleHolder;

	import java.io.File;
	import java.io.IOException;
	import java.io.RandomAccessFile;
	import java.nio.channels.FileChannel;

	/**
	* {@link SampleChunk} stores samples into file and makes them available for read.
	* Stored file = { Header, Sample } * N
	* Header = sample size : int, sample flag : int, sample PTS in micro second : long
	*/
	public class SampleChunk {
	private static final String TAG = "SampleChunk";
	private static final boolean DEBUG = false;

	private final long mCreatedTimeMs;
	private final long mStartPositionUs;
	private SampleChunk mNextChunk;

	// Header = sample size : int, sample flag : int, sample PTS in micro second : long
	private static final int SAMPLE_HEADER_LENGTH = 16;

	private final File mFile;
	private final ChunkCallback mChunkCallback;
	private final SamplePool mSamplePool;
	private RandomAccessFile mAccessFile;
	private long mWriteOffset;
	private boolean mWriteFinished;
	private boolean mIsReading;
	private boolean mIsWriting;

	/**
	* A callback for chunks being committed to permanent storage.
	*/
	public static abstract class ChunkCallback {

	/**
	* Notifies when writing a SampleChunk is completed.
	*
	* @param chunk SampleChunk which is written completely
	*/
	public void onChunkWrite(SampleChunk chunk) {

	}

	/**
	* Notifies when a SampleChunk is deleted.
	*
	* @param chunk SampleChunk which is deleted from storage
	*/
	public void onChunkDelete(SampleChunk chunk) {
	}
	}

	/**
	* A class for SampleChunk creation.
	*/
	public static class SampleChunkCreator {

	/**
	* Returns a newly created SampleChunk to read & write samples.
	*
	* @param samplePool sample allocator
	* @param file filename which will be created newly
	* @param startPositionUs the start position of the earliest sample to be stored
	* @param chunkCallback for total storage usage change notification
	*/
	SampleChunk createSampleChunk(SamplePool samplePool, File file,
	long startPositionUs, ChunkCallback chunkCallback) {
	return new SampleChunk(samplePool, file, startPositionUs, System.currentTimeMillis(),
	chunkCallback);
	}

	/**
	* Returns a newly created SampleChunk which is backed by an existing file.
	* Created SampleChunk is read-only.
	*
	* @param samplePool sample allocator
	* @param bufferDir the directory where the file to read is located
	* @param filename the filename which will be read afterwards
	* @param startPositionUs the start position of the earliest sample in the file
	* @param chunkCallback for total storage usage change notification
	* @param prev the previous SampleChunk just before the newly created SampleChunk
	* @throws IOException
	*/
	SampleChunk loadSampleChunkFromFile(SamplePool samplePool, File bufferDir,
	String filename, long startPositionUs, ChunkCallback chunkCallback,
	SampleChunk prev) throws IOException {
	File file = new File(bufferDir, filename);
	SampleChunk chunk =
	new SampleChunk(samplePool, file, startPositionUs, chunkCallback);
	if (prev != null) {
	prev.mNextChunk = chunk;
	}
	return chunk;
	}
	}

	/**
	* Handles I/O for SampleChunk.
	* Maintains current SampleChunk and the current offset for next I/O operation.
	*/
	static class IoState {
	private SampleChunk mChunk;
	private long mCurrentOffset;

	private boolean equals(SampleChunk chunk, long offset) {
	return chunk == mChunk && mCurrentOffset == offset;
	}

	/**
	* Returns whether read I/O operation is finished.
	*/
	boolean isReadFinished() {
	return mChunk == null;
	}

	/**
	* Returns the start position of the current SampleChunk
	*/
	long getStartPositionUs() {
	return mChunk == null ? 0 : mChunk.getStartPositionUs();
	}

	private void reset(@Nullable SampleChunk chunk) {
	mChunk = chunk;
	mCurrentOffset = 0;
	}

	private void reset(SampleChunk chunk, long offset) {
	mChunk = chunk;
	mCurrentOffset = offset;
	}

	/**
	* Prepares for read I/O operation from a new SampleChunk.
	*
	* @param chunk the new SampleChunk to read from
	* @throws IOException
	*/
	void openRead(SampleChunk chunk, long offset) throws IOException {
	if (mChunk != null) {
	mChunk.closeRead();
	}
	chunk.openRead();
	reset(chunk, offset);
	}

	/**
	* Prepares for write I/O operation to a new SampleChunk.
	*
	* @param chunk the new SampleChunk to write samples afterwards
	* @throws IOException
	*/
	void openWrite(SampleChunk chunk) throws IOException{
	if (mChunk != null) {
	mChunk.closeWrite(chunk);
	}
	chunk.openWrite();
	reset(chunk);
	}

	/**
	* Reads a sample if it is available.
	*
	* @return Returns a sample if it is available, null otherwise.
	* @throws IOException
	*/
	SampleHolder read() throws IOException {
	if (mChunk != null && mChunk.isReadFinished(this)) {
	SampleChunk next = mChunk.mNextChunk;
	mChunk.closeRead();
	if (next != null) {
	next.openRead();
	}
	reset(next);
	}
	if (mChunk != null) {
	try {
	return mChunk.read(this);
	} catch (IllegalStateException e) {
	// Write is finished and there is no additional buffer to read.
	Log.w(TAG, "Tried to read sample over EOS.");
	return null;
	}
	} else {
	return null;
	}
	}

	/**
	* Writes a sample.
	*
	* @param sample to write
	* @param nextChunk if this is {@code null} writes at the current SampleChunk,
	* otherwise close current SampleChunk and writes at this
	* @throws IOException
	*/
	void write(SampleHolder sample, SampleChunk nextChunk)
	throws IOException {
	if (nextChunk != null) {
	if (mChunk == null \|\| mChunk.mNextChunk != null) {
	throw new IllegalStateException("Requested write for wrong SampleChunk");
	}
	mChunk.closeWrite(nextChunk);
	mChunk.mChunkCallback.onChunkWrite(mChunk);
	nextChunk.openWrite();
	reset(nextChunk);
	}
	mChunk.write(sample, this);
	}

	/**
	* Finishes write I/O operation.
	*
	* @throws IOException
	*/
	void closeWrite() throws IOException {
	if (mChunk != null) {
	mChunk.closeWrite(null);
	}
	}

	/**
	* Returns the current SampleChunk for subsequent I/O operation.
	*/
	SampleChunk getChunk() {
	return mChunk;
	}

	/**
	* Returns the current offset of the current SampleChunk for subsequent I/O operation.
	*/
	long getOffset() {
	return mCurrentOffset;
	}

	/**
	* Releases SampleChunk. the SampleChunk will not be used anymore.
	*
	* @param chunk to release
	* @param delete {@code true} when the backed file needs to be deleted,
	* {@code false} otherwise.
	*/
	static void release(SampleChunk chunk, boolean delete) {
	chunk.release(delete);
	}
	}

	@VisibleForTesting
	protected SampleChunk(SamplePool samplePool, File file, long startPositionUs,
	long createdTimeMs, ChunkCallback chunkCallback) {
	mStartPositionUs = startPositionUs;
	mCreatedTimeMs = createdTimeMs;
	mSamplePool = samplePool;
	mFile = file;
	mChunkCallback = chunkCallback;
	}

	// Constructor of SampleChunk which is backed by the given existing file.
	private SampleChunk(SamplePool samplePool, File file, long startPositionUs,
	ChunkCallback chunkCallback) throws IOException {
	mStartPositionUs = startPositionUs;
	mCreatedTimeMs = mStartPositionUs / 1000;
	mSamplePool = samplePool;
	mFile = file;
	mChunkCallback = chunkCallback;
	mWriteFinished = true;
	}

	private void openRead() throws IOException {
	if (!mIsReading) {
	if (mAccessFile == null) {
	mAccessFile = new RandomAccessFile(mFile, "r");
	}
	if (mWriteFinished && mWriteOffset == 0) {
	// Lazy loading of write offset, in order not to load
	// all SampleChunk's write offset at start time of recorded playback.
	mWriteOffset = mAccessFile.length();
	}
	mIsReading = true;
	}
	}

	private void openWrite() throws IOException {
	if (mWriteFinished) {
	throw new IllegalStateException("Opened for write though write is already finished");
	}
	if (!mIsWriting) {
	if (mIsReading) {
	throw new IllegalStateException("Write is requested for "
	+ "an already opened SampleChunk");
	}
	mAccessFile = new RandomAccessFile(mFile, "rw");
	mIsWriting = true;
	}
	}

	private void CloseAccessFileIfNeeded() throws IOException {
	if (!mIsReading && !mIsWriting) {
	try {
	if (mAccessFile != null) {
	mAccessFile.close();
	}
	} finally {
	mAccessFile = null;
	}
	}
	}

	private void closeRead() throws IOException{
	if (mIsReading) {
	mIsReading = false;
	CloseAccessFileIfNeeded();
	}
	}

	private void closeWrite(SampleChunk nextChunk)
	throws IOException {
	if (mIsWriting) {
	mNextChunk = nextChunk;
	mIsWriting = false;
	mWriteFinished = true;
	CloseAccessFileIfNeeded();
	}
	}

	private boolean isReadFinished(IoState state) {
	return mWriteFinished && state.equals(this, mWriteOffset);
	}

	private SampleHolder read(IoState state) throws IOException {
	if (mAccessFile == null \|\| state.mChunk != this) {
	throw new IllegalStateException("Requested read for wrong SampleChunk");
	}
	long offset = state.mCurrentOffset;
	if (offset >= mWriteOffset) {
	if (mWriteFinished) {
	throw new IllegalStateException("Requested read for wrong range");
	} else {
	if (offset != mWriteOffset) {
	Log.e(TAG, "This should not happen!");
	}
	return null;
	}
	}
	mAccessFile.seek(offset);
	int size = mAccessFile.readInt();
	SampleHolder sample = mSamplePool.acquireSample(size);
	sample.size = size;
	sample.flags = mAccessFile.readInt();
	sample.timeUs = mAccessFile.readLong();
	sample.clearData();
	sample.data.put(mAccessFile.getChannel().map(FileChannel.MapMode.READ_ONLY,
	offset + SAMPLE_HEADER_LENGTH, sample.size));
	offset += sample.size + SAMPLE_HEADER_LENGTH;
	state.mCurrentOffset = offset;
	return sample;
	}

	@VisibleForTesting
	protected void write(SampleHolder sample, IoState state)
	throws IOException {
	if (mAccessFile == null \|\| mNextChunk != null \|\| !state.equals(this, mWriteOffset)) {
	throw new IllegalStateException("Requested write for wrong SampleChunk");
	}

	mAccessFile.seek(mWriteOffset);
	mAccessFile.writeInt(sample.size);
	mAccessFile.writeInt(sample.flags);
	mAccessFile.writeLong(sample.timeUs);
	sample.data.position(0).limit(sample.size);
	mAccessFile.getChannel().position(mWriteOffset + SAMPLE_HEADER_LENGTH).write(sample.data);
	mWriteOffset += sample.size + SAMPLE_HEADER_LENGTH;
	state.mCurrentOffset = mWriteOffset;
	}

	private void release(boolean delete) {
	mWriteFinished = true;
	mIsReading = mIsWriting = false;
	try {
	if (mAccessFile != null) {
	mAccessFile.close();
	}
	} catch (IOException e) {
	// Since the SampleChunk will not be reused, ignore exception.
	}
	if (delete) {
	mFile.delete();
	mChunkCallback.onChunkDelete(this);
	}
	}

	/**
	* Returns the start position.
	*/
	public long getStartPositionUs() {
	return mStartPositionUs;
	}

	/**
	* Returns the creation time.
	*/
	public long getCreatedTimeMs() {
	return mCreatedTimeMs;
	}

	/**
	* Returns the current size.
	*/
	public long getSize() {
	return mWriteOffset;
	}
	}