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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.dfs;
-
- import static org.eclipse.jgit.lib.Ref.Storage.NEW;
-
- import java.io.IOException;
- import java.util.Collections;
- import java.util.List;
- import java.util.Map;
- import java.util.concurrent.atomic.AtomicReference;
-
- import org.eclipse.jgit.errors.MissingObjectException;
- import org.eclipse.jgit.lib.ObjectIdRef;
- import org.eclipse.jgit.lib.Ref;
- import org.eclipse.jgit.lib.RefDatabase;
- import org.eclipse.jgit.lib.RefRename;
- import org.eclipse.jgit.lib.SymbolicRef;
- import org.eclipse.jgit.revwalk.RevObject;
- import org.eclipse.jgit.revwalk.RevTag;
- import org.eclipse.jgit.revwalk.RevWalk;
- import org.eclipse.jgit.util.RefList;
- import org.eclipse.jgit.util.RefMap;
-
- /** */
- public abstract class DfsRefDatabase extends RefDatabase {
- private final DfsRepository repository;
-
- private final AtomicReference<RefCache> cache;
-
- /**
- * Initialize the reference database for a repository.
- *
- * @param repository
- * the repository this database instance manages references for.
- */
- protected DfsRefDatabase(DfsRepository repository) {
- this.repository = repository;
- this.cache = new AtomicReference<RefCache>();
- }
-
- /** @return the repository the database holds the references of. */
- protected DfsRepository getRepository() {
- return repository;
- }
-
- boolean exists() throws IOException {
- return 0 < read().size();
- }
-
- @Override
- public Ref getRef(String needle) throws IOException {
- RefCache curr = read();
- for (String prefix : SEARCH_PATH) {
- Ref ref = curr.ids.get(prefix + needle);
- if (ref != null) {
- ref = resolve(ref, 0, curr.ids);
- return ref;
- }
- }
- return null;
- }
-
- private Ref getOneRef(String refName) throws IOException {
- RefCache curr = read();
- Ref ref = curr.ids.get(refName);
- if (ref != null)
- return resolve(ref, 0, curr.ids);
- return ref;
- }
-
- @Override
- public List<Ref> getAdditionalRefs() {
- return Collections.emptyList();
- }
-
- @Override
- public Map<String, Ref> getRefs(String prefix) throws IOException {
- RefCache curr = read();
- RefList<Ref> packed = RefList.emptyList();
- RefList<Ref> loose = curr.ids;
- RefList.Builder<Ref> sym = new RefList.Builder<Ref>(curr.sym.size());
-
- for (int idx = 0; idx < curr.sym.size(); idx++) {
- Ref ref = curr.sym.get(idx);
- String name = ref.getName();
- ref = resolve(ref, 0, loose);
- if (ref != null && ref.getObjectId() != null) {
- sym.add(ref);
- } else {
- // A broken symbolic reference, we have to drop it from the
- // collections the client is about to receive. Should be a
- // rare occurrence so pay a copy penalty.
- int toRemove = loose.find(name);
- if (0 <= toRemove)
- loose = loose.remove(toRemove);
- }
- }
-
- return new RefMap(prefix, packed, loose, sym.toRefList());
- }
-
- private Ref resolve(Ref ref, int depth, RefList<Ref> loose)
- throws IOException {
- if (!ref.isSymbolic())
- return ref;
-
- Ref dst = ref.getTarget();
-
- if (MAX_SYMBOLIC_REF_DEPTH <= depth)
- return null; // claim it doesn't exist
-
- dst = loose.get(dst.getName());
- if (dst == null)
- return ref;
-
- dst = resolve(dst, depth + 1, loose);
- if (dst == null)
- return null;
- return new SymbolicRef(ref.getName(), dst);
- }
-
- @Override
- public Ref peel(Ref ref) throws IOException {
- final Ref oldLeaf = ref.getLeaf();
- if (oldLeaf.isPeeled() || oldLeaf.getObjectId() == null)
- return ref;
-
- Ref newLeaf = doPeel(oldLeaf);
-
- RefCache cur = read();
- int idx = cur.ids.find(oldLeaf.getName());
- if (0 <= idx && cur.ids.get(idx) == oldLeaf) {
- RefList<Ref> newList = cur.ids.set(idx, newLeaf);
- cache.compareAndSet(cur, new RefCache(newList, cur));
- cachePeeledState(oldLeaf, newLeaf);
- }
-
- return recreate(ref, newLeaf);
- }
-
- private Ref doPeel(final Ref leaf) throws MissingObjectException,
- IOException {
- RevWalk rw = new RevWalk(repository);
- try {
- RevObject obj = rw.parseAny(leaf.getObjectId());
- if (obj instanceof RevTag) {
- return new ObjectIdRef.PeeledTag(
- leaf.getStorage(),
- leaf.getName(),
- leaf.getObjectId(),
- rw.peel(obj).copy());
- } else {
- return new ObjectIdRef.PeeledNonTag(
- leaf.getStorage(),
- leaf.getName(),
- leaf.getObjectId());
- }
- } finally {
- rw.release();
- }
- }
-
- private static Ref recreate(Ref old, Ref leaf) {
- if (old.isSymbolic()) {
- Ref dst = recreate(old.getTarget(), leaf);
- return new SymbolicRef(old.getName(), dst);
- }
- return leaf;
- }
-
- @Override
- public DfsRefUpdate newUpdate(String refName, boolean detach)
- throws IOException {
- boolean detachingSymbolicRef = false;
- Ref ref = getOneRef(refName);
- if (ref == null)
- ref = new ObjectIdRef.Unpeeled(NEW, refName, null);
- else
- detachingSymbolicRef = detach && ref.isSymbolic();
-
- if (detachingSymbolicRef) {
- ref = new ObjectIdRef.Unpeeled(NEW, refName, ref.getObjectId());
- }
-
- DfsRefUpdate update = new DfsRefUpdate(this, ref);
- if (detachingSymbolicRef)
- update.setDetachingSymbolicRef();
- return update;
- }
-
- @Override
- public RefRename newRename(String fromName, String toName)
- throws IOException {
- DfsRefUpdate src = newUpdate(fromName, true);
- DfsRefUpdate dst = newUpdate(toName, true);
- return new DfsRefRename(src, dst);
- }
-
- @Override
- public boolean isNameConflicting(String refName) throws IOException {
- RefList<Ref> all = read().ids;
-
- // Cannot be nested within an existing reference.
- int lastSlash = refName.lastIndexOf('/');
- while (0 < lastSlash) {
- String needle = refName.substring(0, lastSlash);
- if (all.contains(needle))
- return true;
- lastSlash = refName.lastIndexOf('/', lastSlash - 1);
- }
-
- // Cannot be the container of an existing reference.
- String prefix = refName + '/';
- int idx = -(all.find(prefix) + 1);
- if (idx < all.size() && all.get(idx).getName().startsWith(prefix))
- return true;
- return false;
- }
-
- @Override
- public void create() {
- // Nothing to do.
- }
-
- @Override
- public void close() {
- clearCache();
- }
-
- void clearCache() {
- cache.set(null);
- }
-
- void stored(Ref ref) {
- RefCache oldCache, newCache;
- do {
- oldCache = cache.get();
- if (oldCache == null)
- return;
- newCache = oldCache.put(ref);
- } while (!cache.compareAndSet(oldCache, newCache));
- }
-
- void removed(String refName) {
- RefCache oldCache, newCache;
- do {
- oldCache = cache.get();
- if (oldCache == null)
- return;
- newCache = oldCache.remove(refName);
- } while (!cache.compareAndSet(oldCache, newCache));
- }
-
- private RefCache read() throws IOException {
- RefCache c = cache.get();
- if (c == null) {
- c = scanAllRefs();
- cache.set(c);
- }
- return c;
- }
-
- /**
- * Read all known references in the repository.
- *
- * @return all current references of the repository.
- * @throws IOException
- * references cannot be accessed.
- */
- protected abstract RefCache scanAllRefs() throws IOException;
-
- /**
- * Compare a reference, and put if it matches.
- *
- * @param oldRef
- * old value to compare to. If the reference is expected to not
- * exist the old value has a storage of
- * {@link org.eclipse.jgit.lib.Ref.Storage#NEW} and an ObjectId
- * value of {@code null}.
- * @param newRef
- * new reference to store.
- * @return true if the put was successful; false otherwise.
- * @throws IOException
- * the reference cannot be put due to a system error.
- */
- protected abstract boolean compareAndPut(Ref oldRef, Ref newRef)
- throws IOException;
-
- /**
- * Compare a reference, and delete if it matches.
- *
- * @param oldRef
- * the old reference information that was previously read.
- * @return true if the remove was successful; false otherwise.
- * @throws IOException
- * the reference could not be removed due to a system error.
- */
- protected abstract boolean compareAndRemove(Ref oldRef) throws IOException;
-
- /**
- * Update the cached peeled state of a reference
- * <p>
- * The ref database invokes this method after it peels a reference that had
- * not been peeled before. This allows the storage to cache the peel state
- * of the reference, and if it is actually peelable, the target that it
- * peels to, so that on-the-fly peeling doesn't have to happen on the next
- * reference read.
- *
- * @param oldLeaf
- * the old reference.
- * @param newLeaf
- * the new reference, with peel information.
- */
- protected void cachePeeledState(Ref oldLeaf, Ref newLeaf) {
- try {
- compareAndPut(oldLeaf, newLeaf);
- } catch (IOException e) {
- // Ignore an exception during caching.
- }
- }
-
- /** Collection of references managed by this database. */
- public static class RefCache {
- final RefList<Ref> ids;
-
- final RefList<Ref> sym;
-
- /**
- * Initialize a new reference cache.
- * <p>
- * The two reference lists supplied must be sorted in correct order
- * (string compare order) by name.
- *
- * @param ids
- * references that carry an ObjectId, and all of {@code sym}.
- * @param sym
- * references that are symbolic references to others.
- */
- public RefCache(RefList<Ref> ids, RefList<Ref> sym) {
- this.ids = ids;
- this.sym = sym;
- }
-
- RefCache(RefList<Ref> ids, RefCache old) {
- this(ids, old.sym);
- }
-
- /** @return number of references in this cache. */
- public int size() {
- return ids.size();
- }
-
- /**
- * Find a reference by name.
- *
- * @param name
- * full name of the reference.
- * @return the reference, if it exists, otherwise null.
- */
- public Ref get(String name) {
- return ids.get(name);
- }
-
- /**
- * Obtain a modified copy of the cache with a ref stored.
- * <p>
- * This cache instance is not modified by this method.
- *
- * @param ref
- * reference to add or replace.
- * @return a copy of this cache, with the reference added or replaced.
- */
- public RefCache put(Ref ref) {
- RefList<Ref> newIds = this.ids.put(ref);
- RefList<Ref> newSym = this.sym;
- if (ref.isSymbolic()) {
- newSym = newSym.put(ref);
- } else {
- int p = newSym.find(ref.getName());
- if (0 <= p)
- newSym = newSym.remove(p);
- }
- return new RefCache(newIds, newSym);
- }
-
- /**
- * Obtain a modified copy of the cache with the ref removed.
- * <p>
- * This cache instance is not modified by this method.
- *
- * @param refName
- * reference to remove, if it exists.
- * @return a copy of this cache, with the reference removed.
- */
- public RefCache remove(String refName) {
- RefList<Ref> newIds = this.ids;
- int p = newIds.find(refName);
- if (0 <= p)
- newIds = newIds.remove(p);
-
- RefList<Ref> newSym = this.sym;
- p = newSym.find(refName);
- if (0 <= p)
- newSym = newSym.remove(p);
- return new RefCache(newIds, newSym);
- }
- }
- }
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