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/*
* Copyright (C) 2010, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.internal.storage.pack;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import org.eclipse.jgit.storage.pack.PackConfig;
class DeltaCache {
private final long size;
private final int entryLimit;
private final ReferenceQueue<byte[]> queue;
private long used;
DeltaCache(PackConfig pc) {
size = pc.getDeltaCacheSize();
entryLimit = pc.getDeltaCacheLimit();
queue = new ReferenceQueue<>();
}
boolean canCache(int length, ObjectToPack src, ObjectToPack res) {
// If the cache would overflow, don't store.
//
if (0 < size && size < used + length) {
checkForGarbageCollectedObjects();
if (0 < size && size < used + length)
return false;
}
if (length < entryLimit) {
used += length;
return true;
}
// If the combined source files are multiple megabytes but the delta
// is on the order of a kilobyte or two, this was likely costly to
// construct. Cache it anyway, even though its over the limit.
//
if (length >> 10 < (src.getWeight() >> 20) + (res.getWeight() >> 21)) {
used += length;
return true;
}
return false;
}
void credit(int reservedSize) {
used -= reservedSize;
}
Ref cache(byte[] data, int actLen, int reservedSize) {
// The caller may have had to allocate more space than is
// required. If we are about to waste anything, shrink it.
//
data = resize(data, actLen);
// When we reserved space for this item we did it for the
// inflated size of the delta, but we were just given the
// compressed version. Adjust the cache cost to match.
//
if (reservedSize != data.length) {
used -= reservedSize;
used += data.length;
}
return new Ref(data, queue);
}
byte[] resize(byte[] data, int actLen) {
if (data.length != actLen) {
byte[] nbuf = new byte[actLen];
System.arraycopy(data, 0, nbuf, 0, actLen);
data = nbuf;
}
return data;
}
private void checkForGarbageCollectedObjects() {
Ref r;
while ((r = (Ref) queue.poll()) != null)
used -= r.cost;
}
static class Ref extends SoftReference<byte[]> {
final int cost;
Ref(byte[] array, ReferenceQueue<byte[]> queue) {
super(array, queue);
cost = array.length;
}
}
}
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