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 static com.google.android.exoplayer2.util.Assertions.checkNotNull;
  import static com.google.android.exoplayer2.util.Util.castNonNull;
  import static java.lang.Math.min;
  
  import androidx.annotation.Nullable;
  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.Log;
  import com.google.android.exoplayer2.util.Util;
  import com.google.errorprone.annotations.CanIgnoreReturnValue;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
  
  /**
   * Writes data into a cache.
   *
   * <p>If the {@link DataSpec} passed to {@link #open(DataSpec)} has the {@code length} field set to
   * {@link C#LENGTH_UNSET} and {@link DataSpec#FLAG_DONT_CACHE_IF_LENGTH_UNKNOWN} set, then {@link
   * #write(byte[], int, int)} calls are ignored.
   */
  public final class CacheDataSink implements DataSink {
  
    /** {@link DataSink.Factory} for {@link CacheDataSink} instances. */
    public static final class Factory implements DataSink.Factory {
  
      private @MonotonicNonNull Cache cache;
      private long fragmentSize;
      private int bufferSize;
  
      /** Creates an instance. */
      public Factory() {
        fragmentSize = CacheDataSink.DEFAULT_FRAGMENT_SIZE;
        bufferSize = CacheDataSink.DEFAULT_BUFFER_SIZE;
      }
  
      /**
       * Sets the cache to which data will be written.
       *
       * <p>Must be called before the factory is used.
       *
       * @param cache The cache to which data will be written.
       * @return This factory.
       */
      @CanIgnoreReturnValue
      public Factory setCache(Cache cache) {
        this.cache = cache;
        return this;
      }
  
      /**
       * Sets the cache file fragment size. For requests that should be fragmented into multiple cache
       * files, this is the maximum size of a cache file in bytes. If set to {@link C#LENGTH_UNSET}
       * then no fragmentation will occur. Using a small value allows for finer-grained cache eviction
       * policies, at the cost of increased overhead both on the cache implementation and the file
       * system. Values under {@code (2 * 1024 * 1024)} are not recommended.
       *
       * <p>The default value is {@link CacheDataSink#DEFAULT_FRAGMENT_SIZE}.
       *
       * @param fragmentSize The fragment size in bytes, or {@link C#LENGTH_UNSET} to disable
       *     fragmentation.
       * @return This factory.
       */
      @CanIgnoreReturnValue
      public Factory setFragmentSize(long fragmentSize) {
        this.fragmentSize = fragmentSize;
        return this;
      }
  
      /**
       * Sets the size of an in-memory buffer used when writing to a cache file. A zero or negative
       * value disables buffering.
       *
       * <p>The default value is {@link CacheDataSink#DEFAULT_BUFFER_SIZE}.
       *
       * @param bufferSize The buffer size in bytes.
       * @return This factory.
       */
      @CanIgnoreReturnValue
      public Factory setBufferSize(int bufferSize) {
        this.bufferSize = bufferSize;
        return this;
      }
  
      @Override
      public DataSink createDataSink() {
        return new CacheDataSink(checkNotNull(cache), fragmentSize, bufferSize);
      }
    }
  
    /** Thrown when an {@link IOException} is encountered when writing data to the sink. */
    public static final class CacheDataSinkException extends CacheException {
  
      public CacheDataSinkException(IOException cause) {
        super(cause);
      }
    }
  
    /** Default {@code fragmentSize} recommended for caching use cases. */
    public static final long DEFAULT_FRAGMENT_SIZE = 5 * 1024 * 1024;
    /** Default buffer size in bytes. */
    public static final int DEFAULT_BUFFER_SIZE = 20 * 1024;
  
    private static final long MIN_RECOMMENDED_FRAGMENT_SIZE = 2 * 1024 * 1024;
    private static final String TAG = "CacheDataSink";
  
    private final Cache cache;
    private final long fragmentSize;
    private final int bufferSize;
  
    @Nullable private DataSpec dataSpec;
    private long dataSpecFragmentSize;
    @Nullable private File file;
    @Nullable private OutputStream outputStream;
    private long outputStreamBytesWritten;
    private long dataSpecBytesWritten;
    private @MonotonicNonNull ReusableBufferedOutputStream bufferedOutputStream;
  
    /**
     * Constructs an instance using {@link #DEFAULT_BUFFER_SIZE}.
     *
     * @param cache The cache into which data should be written.
     * @param fragmentSize For requests that should be fragmented into multiple cache files, this is
     *     the maximum size of a cache file in bytes. If set to {@link C#LENGTH_UNSET} then no
     *     fragmentation will occur. Using a small value allows for finer-grained cache eviction
     *     policies, at the cost of increased overhead both on the cache implementation and the file
     *     system. Values under {@code (2 * 1024 * 1024)} are not recommended.
     */
    public CacheDataSink(Cache cache, long fragmentSize) {
      this(cache, fragmentSize, DEFAULT_BUFFER_SIZE);
    }
  
    /**
     * @param cache The cache into which data should be written.
     * @param fragmentSize For requests that should be fragmented into multiple cache files, this is
     *     the maximum size of a cache file in bytes. If set to {@link C#LENGTH_UNSET} then no
     *     fragmentation will occur. Using a small value allows for finer-grained cache eviction
     *     policies, at the cost of increased overhead both on the cache implementation and the file
     *     system. Values under {@code (2 * 1024 * 1024)} are not recommended.
     * @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 fragmentSize, int bufferSize) {
      Assertions.checkState(
          fragmentSize > 0 || fragmentSize == C.LENGTH_UNSET,
          "fragmentSize must be positive or C.LENGTH_UNSET.");
      if (fragmentSize != C.LENGTH_UNSET && fragmentSize < MIN_RECOMMENDED_FRAGMENT_SIZE) {
        Log.w(
            TAG,
            "fragmentSize is below the minimum recommended value of "
                + MIN_RECOMMENDED_FRAGMENT_SIZE
                + ". This may cause poor cache performance.");
      }
      this.cache = checkNotNull(cache);
      this.fragmentSize = fragmentSize == C.LENGTH_UNSET ? Long.MAX_VALUE : fragmentSize;
      this.bufferSize = bufferSize;
    }
  
    @Override
    public void open(DataSpec dataSpec) throws CacheDataSinkException {
      checkNotNull(dataSpec.key);
      if (dataSpec.length == C.LENGTH_UNSET
          && dataSpec.isFlagSet(DataSpec.FLAG_DONT_CACHE_IF_LENGTH_UNKNOWN)) {
        this.dataSpec = null;
        return;
      }
      this.dataSpec = dataSpec;
      this.dataSpecFragmentSize =
          dataSpec.isFlagSet(DataSpec.FLAG_ALLOW_CACHE_FRAGMENTATION) ? fragmentSize : Long.MAX_VALUE;
      dataSpecBytesWritten = 0;
      try {
        openNextOutputStream(dataSpec);
      } catch (IOException e) {
        throw new CacheDataSinkException(e);
      }
    }
  
    @Override
    public void write(byte[] buffer, int offset, int length) throws CacheDataSinkException {
      @Nullable DataSpec dataSpec = this.dataSpec;
      if (dataSpec == null) {
        return;
      }
      try {
        int bytesWritten = 0;
        while (bytesWritten < length) {
          if (outputStreamBytesWritten == dataSpecFragmentSize) {
            closeCurrentOutputStream();
            openNextOutputStream(dataSpec);
          }
          int bytesToWrite =
              (int) min(length - bytesWritten, dataSpecFragmentSize - outputStreamBytesWritten);
          castNonNull(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(DataSpec dataSpec) throws IOException {
      long length =
          dataSpec.length == C.LENGTH_UNSET
              ? C.LENGTH_UNSET
              : min(dataSpec.length - dataSpecBytesWritten, dataSpecFragmentSize);
      file =
          cache.startFile(
              castNonNull(dataSpec.key), dataSpec.position + dataSpecBytesWritten, length);
      FileOutputStream 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;
    }
  
    private void closeCurrentOutputStream() throws IOException {
      if (outputStream == null) {
        return;
      }
  
      boolean success = false;
      try {
        outputStream.flush();
        success = true;
      } finally {
        Util.closeQuietly(outputStream);
        outputStream = null;
        File fileToCommit = castNonNull(file);
        file = null;
        if (success) {
          cache.commitFile(fileToCommit, outputStreamBytesWritten);
        } else {
          fileToCommit.delete();
        }
      }
    }
  }
  