content: /*
   * 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.google.android.exoplayer2.upstream.cache;
  
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.upstream.DataSink;
  import com.google.android.exoplayer2.upstream.DataSpec;
  import com.google.android.exoplayer2.upstream.cache.Cache.CacheException;
  import com.google.android.exoplayer2.util.Assertions;
  import com.google.android.exoplayer2.util.ReusableBufferedOutputStream;
  import com.google.android.exoplayer2.util.Util;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  
  /**
   * Writes data into a cache.
   *
   * <p>If the {@link DataSpec} object used with {@link #open(DataSpec)} method call has the {@code
   * length} field set to {@link C#LENGTH_UNSET} but {@link
   * DataSpec#FLAG_ALLOW_CACHING_UNKNOWN_LENGTH} isn't set then {@link #write(byte[], int, int)} calls
   * are ignored.
   */
  public final class CacheDataSink implements DataSink {
  
    /** Default buffer size in bytes. */
    public static final int DEFAULT_BUFFER_SIZE = 20480;
  
    private final Cache cache;
    private final long maxCacheFileSize;
    private final int bufferSize;
  
    private DataSpec dataSpec;
    private File file;
    private OutputStream outputStream;
    private FileOutputStream underlyingFileOutputStream;
    private long outputStreamBytesWritten;
    private long dataSpecBytesWritten;
    private ReusableBufferedOutputStream bufferedOutputStream;
  
    /**
     * Thrown when IOException is encountered when writing data into sink.
     */
    public static class CacheDataSinkException extends CacheException {
  
      public CacheDataSinkException(IOException cause) {
        super(cause);
      }
  
    }
  
    /**
     * Constructs a CacheDataSink using the {@link #DEFAULT_BUFFER_SIZE}.
     *
     * @param cache The cache into which data should be written.
     * @param maxCacheFileSize The maximum size of a cache file, in bytes. If the sink is opened for
     *    a {@link DataSpec} whose size exceeds this value, then the data will be fragmented into
     *    multiple cache files.
     */
    public CacheDataSink(Cache cache, long maxCacheFileSize) {
      this(cache, maxCacheFileSize, DEFAULT_BUFFER_SIZE);
    }
  
    /**
     * @param cache The cache into which data should be written.
     * @param maxCacheFileSize The maximum size of a cache file, in bytes. If the sink is opened for
     *    a {@link DataSpec} whose size exceeds this value, then the data will be fragmented into
     *    multiple cache files.
     * @param bufferSize The buffer size in bytes for writing to a cache file. A zero or negative
     *    value disables buffering.
     */
    public CacheDataSink(Cache cache, long maxCacheFileSize, int bufferSize) {
      this.cache = Assertions.checkNotNull(cache);
      this.maxCacheFileSize = maxCacheFileSize;
      this.bufferSize = bufferSize;
    }
  
    @Override
    public void open(DataSpec dataSpec) throws CacheDataSinkException {
      if (dataSpec.length == C.LENGTH_UNSET
          && !dataSpec.isFlagSet(DataSpec.FLAG_ALLOW_CACHING_UNKNOWN_LENGTH)) {
        this.dataSpec = null;
        return;
      }
      this.dataSpec = dataSpec;
      dataSpecBytesWritten = 0;
      try {
        openNextOutputStream();
      } catch (IOException e) {
        throw new CacheDataSinkException(e);
      }
    }
  
    @Override
    public void write(byte[] buffer, int offset, int length) throws CacheDataSinkException {
      if (dataSpec == null) {
        return;
      }
      try {
        int bytesWritten = 0;
        while (bytesWritten < length) {
          if (outputStreamBytesWritten == maxCacheFileSize) {
            closeCurrentOutputStream();
            openNextOutputStream();
          }
          int bytesToWrite = (int) Math.min(length - bytesWritten,
              maxCacheFileSize - outputStreamBytesWritten);
          outputStream.write(buffer, offset + bytesWritten, bytesToWrite);
          bytesWritten += bytesToWrite;
          outputStreamBytesWritten += bytesToWrite;
          dataSpecBytesWritten += bytesToWrite;
        }
      } catch (IOException e) {
        throw new CacheDataSinkException(e);
      }
    }
  
    @Override
    public void close() throws CacheDataSinkException {
      if (dataSpec == null) {
        return;
      }
      try {
        closeCurrentOutputStream();
      } catch (IOException e) {
        throw new CacheDataSinkException(e);
      }
    }
  
    private void openNextOutputStream() throws IOException {
      long maxLength = dataSpec.length == C.LENGTH_UNSET ? maxCacheFileSize
          : Math.min(dataSpec.length - dataSpecBytesWritten, maxCacheFileSize);
      file = cache.startFile(dataSpec.key, dataSpec.absoluteStreamPosition + dataSpecBytesWritten,
          maxLength);
      underlyingFileOutputStream = new FileOutputStream(file);
      if (bufferSize > 0) {
        if (bufferedOutputStream == null) {
          bufferedOutputStream = new ReusableBufferedOutputStream(underlyingFileOutputStream,
              bufferSize);
        } else {
          bufferedOutputStream.reset(underlyingFileOutputStream);
        }
        outputStream = bufferedOutputStream;
      } else {
        outputStream = underlyingFileOutputStream;
      }
      outputStreamBytesWritten = 0;
    }
  
    @SuppressWarnings("ThrowFromFinallyBlock")
    private void closeCurrentOutputStream() throws IOException {
      if (outputStream == null) {
        return;
      }
  
      boolean success = false;
      try {
        outputStream.flush();
        underlyingFileOutputStream.getFD().sync();
        success = true;
      } finally {
        Util.closeQuietly(outputStream);
        outputStream = null;
        File fileToCommit = file;
        file = null;
        if (success) {
          cache.commitFile(fileToCommit);
        } else {
          fileToCommit.delete();
        }
      }
    }
  
  }
  