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Merge consecutive segments for downloading.

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This speeds up downloads where segments have the same URL with different
byte ranges. We limit the merged segments to 20 seconds to ensure the download
progress of demuxed streams is roughly in line with the playable media duration.

Issue:#5978
PiperOrigin-RevId: 280410761
This commit is contained in:
tonihei 2019-11-14 14:03:59 +00:00 committed by Oliver Woodman
parent 51711a0c97
commit c8e7ecd367
2 changed files with 45 additions and 1 deletions
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2
RELEASENOTES.md
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@ -137,6 +137,8 @@
[Cast demo app](https://github.com/google/ExoPlayer/tree/dev-v2/demos/cast).
* TestUtils: Publish the `testutils` module to simplify unit testing with
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) ###

44
library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloader.java
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@ -25,11 +25,13 @@ import com.google.android.exoplayer2.upstream.cache.Cache;
import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
import com.google.android.exoplayer2.upstream.cache.CacheKeyFactory;
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.Util;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
@ -62,6 +64,7 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
}
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 Cache cache;
@ -108,6 +111,8 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
manifest = manifest.copy(streamKeys);
}
List<Segment> segments = getSegments(dataSource, manifest, /* allowIncompleteList= */ false);
Collections.sort(segments);
mergeSegments(segments, cacheKeyFactory);
// Scan the segments, removing any that are fully downloaded.
int totalSegments = segments.size();
@ -134,7 +139,6 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
contentLength = C.LENGTH_UNSET;
}
}
Collections.sort(segments);
// Download the segments.
@Nullable ProgressNotifier progressNotifier = null;
@ -232,6 +236,44 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M>> impleme
/* 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 final ProgressListener progressListener;