// Copyright (C) 2011 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.package com.google.gerrit.server.git;
package com.google.gerrit.server.git;
import com.google.common.cache.Cache;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.server.cache.CacheModule;
import com.google.inject.Inject;
import com.google.inject.Module;
import com.google.inject.Singleton;
import com.google.inject.name.Named;
import org.eclipse.jgit.lib.ObjectId;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
@Singleton
public class TagCache {
private static final String CACHE_NAME = "git_tags";
public static Module module() {
return new CacheModule() {
@Override
protected void configure() {
persist(CACHE_NAME, String.class, EntryVal.class);
bind(TagCache.class);
}
};
}
private final Cache<String, EntryVal> cache;
private final Object createLock = new Object();
@Inject
TagCache(@Named(CACHE_NAME) Cache<String, EntryVal> cache) {
this.cache = cache;
}
/**
* Advise the cache that a reference fast-forwarded.
* <p>
* This operation is not necessary, the cache will automatically detect changes
* made to references and update itself on demand. However, this method may
* allow the cache to update more quickly and reuse the caller's computation of
* the fast-forward status of a branch.
*
* @param name project the branch is contained in.
* @param refName the branch name.
* @param oldValue the old value, before the fast-forward. The cache
* will only update itself if it is still using this old value.
* @param newValue the current value, after the fast-forward.
*/
public void updateFastForward(Project.NameKey name, String refName,
ObjectId oldValue, ObjectId newValue) {
// Be really paranoid and null check everything. This method should
// never fail with an exception. Some of these references can be null
// (e.g. not all projects are cached, or the cache is not current).
//
EntryVal val = cache.getIfPresent(name.get());
if (val != null) {
TagSetHolder holder = val.holder;
if (holder != null) {
TagSet tags = holder.getTagSet();
if (tags != null) {
if (tags.updateFastForward(refName, oldValue, newValue)) {
cache.put(name.get(), val);
}
}
}
}
}
TagSetHolder get(Project.NameKey name) {
EntryVal val = cache.getIfPresent(name.get());
if (val == null) {
synchronized (createLock) {
val = cache.getIfPresent(name.get());
if (val == null) {
val = new EntryVal();
val.holder = new TagSetHolder(name);
cache.put(name.get(), val);
}
}
}
return val.holder;
}
void put(Project.NameKey name, TagSetHolder tags) {
EntryVal val = new EntryVal();
val.holder = tags;
cache.put(name.get(), val);
}
static class EntryVal implements Serializable {
static final long serialVersionUID = 1L;
transient TagSetHolder holder;
private void readObject(ObjectInputStream in) throws IOException,
ClassNotFoundException {
holder = new TagSetHolder(new Project.NameKey(in.readUTF()));
if (in.readBoolean()) {
TagSet tags = new TagSet(holder.getProjectName());
tags.readObject(in);
holder.setTagSet(tags);
}
}
private void writeObject(ObjectOutputStream out) throws IOException {
TagSet tags = holder.getTagSet();
out.writeUTF(holder.getProjectName().get());
out.writeBoolean(tags != null);
if (tags != null) {
tags.writeObject(out);
}
}
}
}