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.source;
  
  import com.google.android.exoplayer2.C;
  
  // TODO: Clarify the requirements for implementing this interface [Internal ref: b/36250203].
  /**
   * A loader that can proceed in approximate synchronization with other loaders.
   */
  public interface SequenceableLoader {
  
    /**
     * A callback to be notified of {@link SequenceableLoader} events.
     */
    interface Callback<T extends SequenceableLoader> {
  
      /**
       * Called by the loader to indicate that it wishes for its {@link #continueLoading(long)} method
       * to be called when it can continue to load data. Called on the playback thread.
       */
      void onContinueLoadingRequested(T source);
  
    }
  
    /**
     * Returns an estimate of the position up to which data is buffered.
     *
     * @return An estimate of the absolute position in microseconds up to which data is buffered, or
     *     {@link C#TIME_END_OF_SOURCE} if the data is fully buffered.
     */
    long getBufferedPositionUs();
  
    /**
     * Returns the next load time, or {@link C#TIME_END_OF_SOURCE} if loading has finished.
     */
    long getNextLoadPositionUs();
  
    /**
     * Attempts to continue loading.
     *
     * @param positionUs The current playback position in microseconds. If playback of the period to
     *     which this loader belongs has not yet started, the value will be the starting position
     *     in the period minus the duration of any media in previous periods still to be played.
     * @return True if progress was made, meaning that {@link #getNextLoadPositionUs()} will return
     *     a different value than prior to the call. False otherwise.
     */
    boolean continueLoading(long positionUs);
  
    /**
     * Re-evaluates the buffer given the playback position.
     *
     * <p>Re-evaluation may discard buffered media so that it can be re-buffered in a different
     * quality.
     *
     * @param positionUs The current playback position in microseconds. If playback of this period has
     *     not yet started, the value will be the starting position in this period minus the duration
     *     of any media in previous periods still to be played.
     */
    void reevaluateBuffer(long positionUs);
  }
  