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/*
* 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 org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.cache;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.cache.Cache.CacheException;
import java.util.TreeSet;
/** Evicts least recently used cache files first. */
public final class LeastRecentlyUsedCacheEvictor implements CacheEvictor {
private final long maxBytes;
private final TreeSet<CacheSpan> leastRecentlyUsed;
private long currentSize;
public LeastRecentlyUsedCacheEvictor(long maxBytes) {
this.maxBytes = maxBytes;
this.leastRecentlyUsed = new TreeSet<>(LeastRecentlyUsedCacheEvictor::compare);
}
@Override
public boolean requiresCacheSpanTouches() {
return true;
}
@Override
public void onCacheInitialized() {
// Do nothing.
}
@Override
public void onStartFile(Cache cache, String key, long position, long length) {
if (length != C.LENGTH_UNSET) {
evictCache(cache, length);
}
}
@Override
public void onSpanAdded(Cache cache, CacheSpan span) {
leastRecentlyUsed.add(span);
currentSize += span.length;
evictCache(cache, 0);
}
@Override
public void onSpanRemoved(Cache cache, CacheSpan span) {
leastRecentlyUsed.remove(span);
currentSize -= span.length;
}
@Override
public void onSpanTouched(Cache cache, CacheSpan oldSpan, CacheSpan newSpan) {
onSpanRemoved(cache, oldSpan);
onSpanAdded(cache, newSpan);
}
private void evictCache(Cache cache, long requiredSpace) {
while (currentSize + requiredSpace > maxBytes && !leastRecentlyUsed.isEmpty()) {
try {
cache.removeSpan(leastRecentlyUsed.first());
} catch (CacheException e) {
// do nothing.
}
}
}
private static int compare(CacheSpan lhs, CacheSpan rhs) {
long lastTouchTimestampDelta = lhs.lastTouchTimestamp - rhs.lastTouchTimestamp;
if (lastTouchTimestampDelta == 0) {
// Use the standard compareTo method as a tie-break.
return lhs.compareTo(rhs);
}
return lhs.lastTouchTimestamp < rhs.lastTouchTimestamp ? -1 : 1;
}
}
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