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- /*
- * Copyright (C) 2008, Google Inc.
- * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
- * 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.dircache;
-
- import java.io.IOException;
-
- /**
- * Generic update/editing support for {@link DirCache}.
- * <p>
- * The different update strategies extend this class to provide their own unique
- * services to applications.
- */
- abstract class BaseDirCacheEditor {
- /** The cache instance this editor updates during {@link #finish()}. */
- protected DirCache cache;
-
- /**
- * Entry table this builder will eventually replace into {@link #cache}.
- * <p>
- * Use {@link #fastAdd(DirCacheEntry)} or {@link #fastKeep(int, int)} to
- * make additions to this table. The table is automatically expanded if it
- * is too small for a new addition.
- * <p>
- * Typically the entries in here are sorted by their path names, just like
- * they are in the DirCache instance.
- */
- protected DirCacheEntry[] entries;
-
- /** Total number of valid entries in {@link #entries}. */
- protected int entryCnt;
-
- /**
- * Construct a new editor.
- *
- * @param dc
- * the cache this editor will eventually update.
- * @param ecnt
- * estimated number of entries the editor will have upon
- * completion. This sizes the initial entry table.
- */
- protected BaseDirCacheEditor(final DirCache dc, final int ecnt) {
- cache = dc;
- entries = new DirCacheEntry[ecnt];
- }
-
- /**
- * @return the cache we will update on {@link #finish()}.
- */
- public DirCache getDirCache() {
- return cache;
- }
-
- /**
- * Append one entry into the resulting entry list.
- * <p>
- * The entry is placed at the end of the entry list. The caller is
- * responsible for making sure the final table is correctly sorted.
- * <p>
- * The {@link #entries} table is automatically expanded if there is
- * insufficient space for the new addition.
- *
- * @param newEntry
- * the new entry to add.
- */
- protected void fastAdd(final DirCacheEntry newEntry) {
- if (entries.length == entryCnt) {
- final DirCacheEntry[] n = new DirCacheEntry[(entryCnt + 16) * 3 / 2];
- System.arraycopy(entries, 0, n, 0, entryCnt);
- entries = n;
- }
- entries[entryCnt++] = newEntry;
- }
-
- /**
- * Add a range of existing entries from the destination cache.
- * <p>
- * The entries are placed at the end of the entry list, preserving their
- * current order. The caller is responsible for making sure the final table
- * is correctly sorted.
- * <p>
- * This method copies from the destination cache, which has not yet been
- * updated with this editor's new table. So all offsets into the destination
- * cache are not affected by any updates that may be currently taking place
- * in this editor.
- * <p>
- * The {@link #entries} table is automatically expanded if there is
- * insufficient space for the new additions.
- *
- * @param pos
- * first entry to copy from the destination cache.
- * @param cnt
- * number of entries to copy.
- */
- protected void fastKeep(final int pos, int cnt) {
- if (entryCnt + cnt > entries.length) {
- final int m1 = (entryCnt + 16) * 3 / 2;
- final int m2 = entryCnt + cnt;
- final DirCacheEntry[] n = new DirCacheEntry[Math.max(m1, m2)];
- System.arraycopy(entries, 0, n, 0, entryCnt);
- entries = n;
- }
-
- cache.toArray(pos, entries, entryCnt, cnt);
- entryCnt += cnt;
- }
-
- /**
- * Finish this builder and update the destination {@link DirCache}.
- * <p>
- * When this method completes this builder instance is no longer usable by
- * the calling application. A new builder must be created to make additional
- * changes to the index entries.
- * <p>
- * After completion the DirCache returned by {@link #getDirCache()} will
- * contain all modifications.
- * <p>
- * <i>Note to implementors:</i> Make sure {@link #entries} is fully sorted
- * then invoke {@link #replace()} to update the DirCache with the new table.
- */
- public abstract void finish();
-
- /**
- * Update the DirCache with the contents of {@link #entries}.
- * <p>
- * This method should be invoked only during an implementation of
- * {@link #finish()}, and only after {@link #entries} is sorted.
- */
- protected void replace() {
- if (entryCnt < entries.length / 2) {
- final DirCacheEntry[] n = new DirCacheEntry[entryCnt];
- System.arraycopy(entries, 0, n, 0, entryCnt);
- entries = n;
- }
- cache.replace(entries, entryCnt);
- }
-
- /**
- * Finish, write, commit this change, and release the index lock.
- * <p>
- * If this method fails (returns false) the lock is still released.
- * <p>
- * This is a utility method for applications as the finish-write-commit
- * pattern is very common after using a builder to update entries.
- *
- * @return true if the commit was successful and the file contains the new
- * data; false if the commit failed and the file remains with the
- * old data.
- * @throws IllegalStateException
- * the lock is not held.
- * @throws IOException
- * the output file could not be created. The caller no longer
- * holds the lock.
- */
- public boolean commit() throws IOException {
- finish();
- cache.write();
- return cache.commit();
- }
- }
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