Mercurial > jhg
view src/org/tmatesoft/hg/internal/RevisionLookup.java @ 643:a8ce405da1f5
v1.2 line of dev: update versions, use patch merge code by default
author | Artem Tikhomirov <tikhomirov.artem@gmail.com> |
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date | Wed, 19 Jun 2013 16:03:11 +0200 (2013-06-19) |
parents | 6526d8adbc0f |
children |
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/* * Copyright (c) 2013 TMate Software Ltd * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * For information on how to redistribute this software under * the terms of a license other than GNU General Public License * contact TMate Software at support@hg4j.com */ package org.tmatesoft.hg.internal; import static org.tmatesoft.hg.repo.HgRepository.BAD_REVISION; import java.util.Arrays; import org.tmatesoft.hg.core.Nodeid; import org.tmatesoft.hg.repo.HgInvalidControlFileException; import org.tmatesoft.hg.repo.HgInvalidRevisionException; import org.tmatesoft.hg.repo.HgRevisionMap; import org.tmatesoft.hg.repo.HgRuntimeException; /** * Lite alternative to {@link HgRevisionMap}, to speed up nodeid to index conversion without consuming too much memory. * E.g. for a 100k revisions, {@link HgRevisionMap} consumes 3 * (N * sizeof(int)) for indexes plus 48 bytes per * Nodeid instance, total (12+48)*N = 6 mb of memory. {RevisionLookup} instead keeps only Nodeid hashes, (N * sizeof(int) = 400 kb), * but is slower in lookup, O(N/2) to find potential match plus disk read operatin (or few, in an unlikely case of hash collisions). * * @author Artem Tikhomirov * @author TMate Software Ltd. */ public class RevisionLookup implements RevlogStream.Inspector { private final RevlogStream content; private int[] nodeidHashes; public RevisionLookup(RevlogStream stream) { assert stream != null; content = stream; } public static RevisionLookup createFor(RevlogStream stream) throws HgRuntimeException { RevisionLookup rv = new RevisionLookup(stream); int revCount = stream.revisionCount(); rv.prepare(revCount); if (revCount > 0) { stream.iterate(0, revCount - 1, false, rv); } return rv; } public void prepare(int count) { nodeidHashes = new int[count]; Arrays.fill(nodeidHashes, BAD_REVISION); } public void next(int index, byte[] nodeid) { nodeidHashes[index] = Nodeid.hashCode(nodeid); } public void next(int index, Nodeid nodeid) { nodeidHashes[index] = nodeid.hashCode(); } public int findIndex(Nodeid nodeid) throws HgInvalidControlFileException, HgInvalidRevisionException { final int hash = nodeid.hashCode(); for (int i = 0; i < nodeidHashes.length; i++) { if (nodeidHashes[i] == hash) { byte[] nodeidAtI = content.nodeid(i); if (nodeid.equalsTo(nodeidAtI)) { return i; } } // else: false match (only 4 head bytes matched, continue loop } return BAD_REVISION; } public void next(int revisionIndex, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, DataAccess data) { next(revisionIndex, nodeid); } }