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- /*
- * Copyright (C) 2011, Google Inc.
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.storage.dht;
-
- import java.io.IOException;
- import java.util.HashMap;
-
- import org.eclipse.jgit.lib.AnyObjectId;
- import org.eclipse.jgit.lib.ObjectLoader;
- import org.eclipse.jgit.storage.dht.DhtReader.ChunkAndOffset;
- import org.eclipse.jgit.storage.dht.RefDataUtil.IdWithChunk;
-
- final class RecentChunks {
- private final DhtReader reader;
-
- private final DhtReader.Statistics stats;
-
- private final HashMap<ChunkKey, Node> byKey;
-
- private int maxBytes;
-
- private int curBytes;
-
- private Node lruHead;
-
- private Node lruTail;
-
- RecentChunks(DhtReader reader) {
- this.reader = reader;
- this.stats = reader.getStatistics();
- this.byKey = new HashMap<ChunkKey, Node>();
- this.maxBytes = reader.getOptions().getChunkLimit();
- }
-
- void setMaxBytes(int newMax) {
- maxBytes = Math.max(0, newMax);
- if (0 < maxBytes)
- prune();
- else
- clear();
- }
-
- PackChunk get(ChunkKey key) {
- Node n = byKey.get(key);
- if (n != null) {
- hit(n);
- stats.recentChunks_Hits++;
- return n.chunk;
- }
- stats.recentChunks_Miss++;
- return null;
- }
-
- void put(PackChunk chunk) {
- Node n = byKey.get(chunk.getChunkKey());
- if (n != null && n.chunk == chunk) {
- hit(n);
- return;
- }
-
- curBytes += chunk.getTotalSize();
- prune();
-
- n = new Node();
- n.chunk = chunk;
- byKey.put(chunk.getChunkKey(), n);
- first(n);
- }
-
- private void prune() {
- while (maxBytes < curBytes) {
- Node n = lruTail;
- if (n == null)
- break;
-
- PackChunk c = n.chunk;
- curBytes -= c.getTotalSize();
- byKey.remove(c.getChunkKey());
- remove(n);
- }
- }
-
- ObjectLoader open(RepositoryKey repo, AnyObjectId objId, int typeHint)
- throws IOException {
- if (objId instanceof IdWithChunk) {
- PackChunk chunk = get(((IdWithChunk) objId).getChunkKey());
- if (chunk != null) {
- int pos = chunk.findOffset(repo, objId);
- if (0 <= pos)
- return PackChunk.read(chunk, pos, reader, typeHint);
- }
-
- // IdWithChunk is only a hint, and can be wrong. Locally
- // searching is faster than looking in the Database.
- }
-
- for (Node n = lruHead; n != null; n = n.next) {
- int pos = n.chunk.findOffset(repo, objId);
- if (0 <= pos) {
- hit(n);
- stats.recentChunks_Hits++;
- return PackChunk.read(n.chunk, pos, reader, typeHint);
- }
- }
-
- return null;
- }
-
- ChunkAndOffset find(RepositoryKey repo, AnyObjectId objId) {
- if (objId instanceof IdWithChunk) {
- PackChunk chunk = get(((IdWithChunk) objId).getChunkKey());
- if (chunk != null) {
- int pos = chunk.findOffset(repo, objId);
- if (0 <= pos)
- return new ChunkAndOffset(chunk, pos);
- }
-
- // IdWithChunk is only a hint, and can be wrong. Locally
- // searching is faster than looking in the Database.
- }
-
- for (Node n = lruHead; n != null; n = n.next) {
- int pos = n.chunk.findOffset(repo, objId);
- if (0 <= pos) {
- hit(n);
- stats.recentChunks_Hits++;
- return new ChunkAndOffset(n.chunk, pos);
- }
- }
-
- return null;
- }
-
- boolean has(RepositoryKey repo, AnyObjectId objId) {
- for (Node n = lruHead; n != null; n = n.next) {
- int pos = n.chunk.findOffset(repo, objId);
- if (0 <= pos) {
- hit(n);
- stats.recentChunks_Hits++;
- return true;
- }
- }
- return false;
- }
-
- void clear() {
- curBytes = 0;
- lruHead = null;
- lruTail = null;
- byKey.clear();
- }
-
- private void hit(Node n) {
- if (lruHead != n) {
- remove(n);
- first(n);
- }
- }
-
- private void remove(Node node) {
- Node p = node.prev;
- Node n = node.next;
-
- if (p != null)
- p.next = n;
- if (n != null)
- n.prev = p;
-
- if (lruHead == node)
- lruHead = n;
- if (lruTail == node)
- lruTail = p;
- }
-
- private void first(Node node) {
- Node h = lruHead;
-
- node.prev = null;
- node.next = h;
-
- if (h != null)
- h.prev = node;
- else
- lruTail = node;
-
- lruHead = node;
- }
-
- private static class Node {
- PackChunk chunk;
-
- Node prev;
-
- Node next;
- }
- }
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