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* changes: Unpack and cache large deltas as loose objects Remember loose objects and fast-track their lookup Correctly name DeltaBaseCachestable-0.9
Matthias Sohn
14 years ago
committed by
Code Review
10 changed files with 402 additions and 192 deletions
@ -0,0 +1,195 @@
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/* |
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* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.storage.file; |
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import java.lang.ref.SoftReference; |
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class DeltaBaseCache { |
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private static final int CACHE_SZ = 1024; |
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private static final SoftReference<Entry> DEAD; |
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private static int hash(final long position) { |
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return (((int) position) << 22) >>> 22; |
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} |
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private static int maxByteCount; |
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private static final Slot[] cache; |
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private static Slot lruHead; |
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private static Slot lruTail; |
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private static int openByteCount; |
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static { |
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DEAD = new SoftReference<Entry>(null); |
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maxByteCount = new WindowCacheConfig().getDeltaBaseCacheLimit(); |
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cache = new Slot[CACHE_SZ]; |
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for (int i = 0; i < CACHE_SZ; i++) |
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cache[i] = new Slot(); |
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} |
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static synchronized void reconfigure(final WindowCacheConfig cfg) { |
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final int dbLimit = cfg.getDeltaBaseCacheLimit(); |
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if (maxByteCount != dbLimit) { |
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maxByteCount = dbLimit; |
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releaseMemory(); |
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} |
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} |
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static synchronized Entry get(final PackFile pack, final long position) { |
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final Slot e = cache[hash(position)]; |
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if (e.provider == pack && e.position == position) { |
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final Entry buf = e.data.get(); |
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if (buf != null) { |
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moveToHead(e); |
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return buf; |
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} |
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} |
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return null; |
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} |
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static synchronized void store(final PackFile pack, final long position, |
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final byte[] data, final int objectType) { |
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if (data.length > maxByteCount) |
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return; // Too large to cache.
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final Slot e = cache[hash(position)]; |
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clearEntry(e); |
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openByteCount += data.length; |
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releaseMemory(); |
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e.provider = pack; |
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e.position = position; |
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e.sz = data.length; |
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e.data = new SoftReference<Entry>(new Entry(data, objectType)); |
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moveToHead(e); |
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} |
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private static void releaseMemory() { |
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while (openByteCount > maxByteCount && lruTail != null) { |
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final Slot currOldest = lruTail; |
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final Slot nextOldest = currOldest.lruPrev; |
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clearEntry(currOldest); |
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currOldest.lruPrev = null; |
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currOldest.lruNext = null; |
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if (nextOldest == null) |
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lruHead = null; |
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else |
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nextOldest.lruNext = null; |
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lruTail = nextOldest; |
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} |
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} |
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static synchronized void purge(final PackFile file) { |
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for (final Slot e : cache) { |
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if (e.provider == file) { |
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clearEntry(e); |
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unlink(e); |
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} |
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} |
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} |
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private static void moveToHead(final Slot e) { |
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unlink(e); |
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e.lruPrev = null; |
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e.lruNext = lruHead; |
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if (lruHead != null) |
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lruHead.lruPrev = e; |
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else |
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lruTail = e; |
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lruHead = e; |
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} |
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private static void unlink(final Slot e) { |
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final Slot prev = e.lruPrev; |
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final Slot next = e.lruNext; |
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if (prev != null) |
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prev.lruNext = next; |
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if (next != null) |
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next.lruPrev = prev; |
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} |
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private static void clearEntry(final Slot e) { |
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openByteCount -= e.sz; |
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e.provider = null; |
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e.data = DEAD; |
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e.sz = 0; |
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} |
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private DeltaBaseCache() { |
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throw new UnsupportedOperationException(); |
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} |
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static class Entry { |
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final byte[] data; |
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final int type; |
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Entry(final byte[] aData, final int aType) { |
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data = aData; |
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type = aType; |
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} |
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} |
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private static class Slot { |
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Slot lruPrev; |
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Slot lruNext; |
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PackFile provider; |
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long position; |
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int sz; |
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SoftReference<Entry> data = DEAD; |
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} |
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} |
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