Revert "Merge consecutive segments for downloading."

This reverts commit c8e7ecd3.

RELEASENOTES.md

@@ -140,8 +140,6 @@
     [Cast demo app](https://github.com/google/ExoPlayer/tree/dev-v2/demos/cast).
     [Cast demo app](https://github.com/google/ExoPlayer/tree/dev-v2/demos/cast).
 * TestUtils: Publish the `testutils` module to simplify unit testing with
 * TestUtils: Publish the `testutils` module to simplify unit testing with
   ExoPlayer ([#6267](https://github.com/google/ExoPlayer/issues/6267)).
   ExoPlayer ([#6267](https://github.com/google/ExoPlayer/issues/6267)).
-* Downloads: Merge downloads in `SegmentDownloader` to improve overall download
-  speed ([#5978](https://github.com/google/ExoPlayer/issues/5978)).
 
 
 ### 2.10.7 (2019-11-12) ###
 ### 2.10.7 (2019-11-12) ###
 
 

library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloader.java

@@ -25,13 +25,11 @@ import com.google.android.exoplayer2.upstream.cache.Cache;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
 import com.google.android.exoplayer2.upstream.cache.CacheKeyFactory;
 import com.google.android.exoplayer2.upstream.cache.CacheKeyFactory;
 import com.google.android.exoplayer2.upstream.cache.CacheUtil;
 import com.google.android.exoplayer2.upstream.cache.CacheUtil;
-import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.PriorityTaskManager;
 import com.google.android.exoplayer2.util.PriorityTaskManager;
 import com.google.android.exoplayer2.util.Util;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 
@@ -64,7 +62,6 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
   }
   }
 
 
   private static final int BUFFER_SIZE_BYTES = 128 * 1024;
   private static final int BUFFER_SIZE_BYTES = 128 * 1024;
-  private static final long MAX_MERGED_SEGMENT_START_TIME_DIFF_US = 20 * C.MICROS_PER_SECOND;
 
 
   private final DataSpec manifestDataSpec;
   private final DataSpec manifestDataSpec;
   private final Cache cache;
   private final Cache cache;
@@ -111,8 +108,6 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
         manifest = manifest.copy(streamKeys);
         manifest = manifest.copy(streamKeys);
       }
       }
       List<Segment> segments = getSegments(dataSource, manifest, /* allowIncompleteList= */ false);
       List<Segment> segments = getSegments(dataSource, manifest, /* allowIncompleteList= */ false);
-      Collections.sort(segments);
-      mergeSegments(segments, cacheKeyFactory);
 
 
       // Scan the segments, removing any that are fully downloaded.
       // Scan the segments, removing any that are fully downloaded.
       int totalSegments = segments.size();
       int totalSegments = segments.size();
@@ -139,6 +134,7 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
           contentLength = C.LENGTH_UNSET;
           contentLength = C.LENGTH_UNSET;
         }
         }
       }
       }
+      Collections.sort(segments);
 
 
       // Download the segments.
       // Download the segments.
       @Nullable ProgressNotifier progressNotifier = null;
       @Nullable ProgressNotifier progressNotifier = null;
@@ -236,44 +232,6 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
         /* flags= */ DataSpec.FLAG_ALLOW_GZIP);
         /* flags= */ DataSpec.FLAG_ALLOW_GZIP);
   }
   }
 
 
-  private static void mergeSegments(List<Segment> segments, CacheKeyFactory keyFactory) {
-    HashMap<String, Integer> lastIndexByCacheKey = new HashMap<>();
-    int nextOutIndex = 0;
-    for (int i = 0; i < segments.size(); i++) {
-      Segment segment = segments.get(i);
-      String cacheKey = keyFactory.buildCacheKey(segment.dataSpec);
-      @Nullable Integer lastIndex = lastIndexByCacheKey.get(cacheKey);
-      @Nullable Segment lastSegment = lastIndex == null ? null : segments.get(lastIndex);
-      if (lastSegment == null
-          || segment.startTimeUs > lastSegment.startTimeUs + MAX_MERGED_SEGMENT_START_TIME_DIFF_US
-          || !canMergeSegments(lastSegment.dataSpec, segment.dataSpec)) {
-        lastIndexByCacheKey.put(cacheKey, nextOutIndex);
-        segments.set(nextOutIndex, segment);
-        nextOutIndex++;
-      } else {
-        long mergedLength =
-            segment.dataSpec.length == C.LENGTH_UNSET
-                ? C.LENGTH_UNSET
-                : lastSegment.dataSpec.length + segment.dataSpec.length;
-        DataSpec mergedDataSpec = lastSegment.dataSpec.subrange(/* offset= */ 0, mergedLength);
-        segments.set(
-            Assertions.checkNotNull(lastIndex),
-            new Segment(lastSegment.startTimeUs, mergedDataSpec));
-      }
-    }
-    Util.removeRange(segments, /* fromIndex= */ nextOutIndex, /* toIndex= */ segments.size());
-  }
-
-  private static boolean canMergeSegments(DataSpec dataSpec1, DataSpec dataSpec2) {
-    return dataSpec1.uri.equals(dataSpec2.uri)
-        && dataSpec1.length != C.LENGTH_UNSET
-        && (dataSpec1.absoluteStreamPosition + dataSpec1.length == dataSpec2.absoluteStreamPosition)
-        && Util.areEqual(dataSpec1.key, dataSpec2.key)
-        && dataSpec1.flags == dataSpec2.flags
-        && dataSpec1.httpMethod == dataSpec2.httpMethod
-        && dataSpec1.httpRequestHeaders.equals(dataSpec2.httpRequestHeaders);
-  }
-
   private static final class ProgressNotifier implements CacheUtil.ProgressListener {
   private static final class ProgressNotifier implements CacheUtil.ProgressListener {
 
 
     private final ProgressListener progressListener;
     private final ProgressListener progressListener;