com.google.gerrit.server.git.ScanningChangeCacheImpl.java Source code

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Here is the source code for com.google.gerrit.server.git.ScanningChangeCacheImpl.java

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// Copyright (C) 2015 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;

import static com.google.gerrit.server.git.SearchingChangeCacheImpl.ID_CACHE;

import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Iterables;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.cache.CacheModule;
import com.google.gerrit.server.util.ManualRequestContext;
import com.google.gerrit.server.util.OneOffRequestContext;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Module;
import com.google.inject.Singleton;
import com.google.inject.TypeLiteral;
import com.google.inject.name.Named;

import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutionException;

@Singleton
public class ScanningChangeCacheImpl implements ChangeCache {
    private static final Logger log = LoggerFactory.getLogger(ScanningChangeCacheImpl.class);

    public static Module module() {
        return new CacheModule() {
            @Override
            protected void configure() {
                bind(ChangeCache.class).to(ScanningChangeCacheImpl.class);
                cache(ID_CACHE, Project.NameKey.class, new TypeLiteral<List<Change>>() {
                }).maximumWeight(0).loader(Loader.class);
            }
        };
    }

    private final LoadingCache<Project.NameKey, List<Change>> cache;

    @Inject
    ScanningChangeCacheImpl(@Named(ID_CACHE) LoadingCache<Project.NameKey, List<Change>> cache) {
        this.cache = cache;
    }

    @Override
    public List<Change> get(Project.NameKey name) {
        try {
            return cache.get(name);
        } catch (ExecutionException e) {
            log.warn("Cannot fetch changes for " + name, e);
            return Collections.emptyList();
        }
    }

    static class Loader extends CacheLoader<Project.NameKey, List<Change>> {
        private final GitRepositoryManager repoManager;
        private final OneOffRequestContext requestContext;

        @Inject
        Loader(GitRepositoryManager repoManager, OneOffRequestContext requestContext) {
            this.repoManager = repoManager;
            this.requestContext = requestContext;
        }

        @Override
        public List<Change> load(Project.NameKey key) throws Exception {
            try (Repository repo = repoManager.openRepository(key);
                    ManualRequestContext ctx = requestContext.open()) {
                return scan(repo, ctx.getReviewDbProvider().get());
            }
        }

    }

    public static List<Change> scan(Repository repo, ReviewDb db) throws OrmException, IOException {
        Map<String, Ref> refs = repo.getRefDatabase().getRefs(RefNames.REFS_CHANGES);
        Set<Change.Id> ids = new LinkedHashSet<>();
        for (Ref r : refs.values()) {
            Change.Id id = Change.Id.fromRef(r.getName());
            if (id != null) {
                ids.add(id);
            }
        }
        List<Change> changes = new ArrayList<>(ids.size());
        // A batch size of N may overload get(Iterable), so use something smaller,
        // but still >1.
        for (List<Change.Id> batch : Iterables.partition(ids, 30)) {
            Iterables.addAll(changes, db.changes().get(batch));
        }
        return changes;
    }
}