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// Copyright (C) 2020 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.patch.diff;
import static com.google.common.collect.ImmutableList.toImmutableList;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Sets;
import com.google.common.collect.Streams;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.Patch.ChangeType;
import com.google.gerrit.server.cache.CacheModule;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.patch.DiffNotAvailableException;
import com.google.gerrit.server.patch.DiffUtil;
import com.google.gerrit.server.patch.gitdiff.GitModifiedFilesCache;
import com.google.gerrit.server.patch.gitdiff.GitModifiedFilesCacheImpl;
import com.google.gerrit.server.patch.gitdiff.GitModifiedFilesCacheKey;
import com.google.gerrit.server.patch.gitdiff.ModifiedFile;
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 java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.stream.Stream;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
/**
* A cache for the list of Git modified files between 2 commits (patchsets) with extra Gerrit logic.
*
* <p>The loader of this cache wraps a {@link GitModifiedFilesCache} to retrieve the git modified
* files.
*
* <p>If the {@link ModifiedFilesCacheKey#aCommit()} is equal to {@link ObjectId#zeroId()}, the diff
* will be evaluated against the empty tree, and the result will be exactly the same as the caller
* can get from {@link GitModifiedFilesCache#get(GitModifiedFilesCacheKey)}
*/
@Singleton
public class ModifiedFilesCacheImpl implements ModifiedFilesCache {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
private static final String MODIFIED_FILES = "modified_files";
private final LoadingCache<ModifiedFilesCacheKey, ImmutableList<ModifiedFile>> cache;
public static Module module() {
return new CacheModule() {
@Override
protected void configure() {
bind(ModifiedFilesCache.class).to(ModifiedFilesCacheImpl.class);
// The documentation has some defaults and recommendations for setting the cache
// attributes:
// https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#cache.
// The cache is using the default disk limit as per section cache.<name>.diskLimit
// in the cache documentation link.
persist(
ModifiedFilesCacheImpl.MODIFIED_FILES,
ModifiedFilesCacheKey.class,
new TypeLiteral<ImmutableList<ModifiedFile>>() {})
.keySerializer(ModifiedFilesCacheKey.Serializer.INSTANCE)
.valueSerializer(GitModifiedFilesCacheImpl.ValueSerializer.INSTANCE)
.maximumWeight(10 << 20)
.weigher(ModifiedFilesWeigher.class)
.version(4)
.loader(ModifiedFilesLoader.class);
}
};
}
@Inject
public ModifiedFilesCacheImpl(
@Named(ModifiedFilesCacheImpl.MODIFIED_FILES)
LoadingCache<ModifiedFilesCacheKey, ImmutableList<ModifiedFile>> cache) {
this.cache = cache;
}
@Override
public ImmutableList<ModifiedFile> get(ModifiedFilesCacheKey key)
throws DiffNotAvailableException {
try {
return cache.get(key);
} catch (Exception e) {
throw new DiffNotAvailableException(e);
}
}
static class ModifiedFilesLoader
extends CacheLoader<ModifiedFilesCacheKey, ImmutableList<ModifiedFile>> {
private final GitModifiedFilesCache gitCache;
private final GitRepositoryManager repoManager;
@Inject
ModifiedFilesLoader(GitModifiedFilesCache gitCache, GitRepositoryManager repoManager) {
this.gitCache = gitCache;
this.repoManager = repoManager;
}
@Override
public ImmutableList<ModifiedFile> load(ModifiedFilesCacheKey key)
throws IOException, DiffNotAvailableException {
try (Repository repo = repoManager.openRepository(key.project());
RevWalk rw = new RevWalk(repo.newObjectReader())) {
return loadModifiedFiles(key, rw);
}
}
private ImmutableList<ModifiedFile> loadModifiedFiles(ModifiedFilesCacheKey key, RevWalk rw)
throws IOException, DiffNotAvailableException {
ObjectId aTree =
key.aCommit().equals(ObjectId.zeroId())
? key.aCommit()
: DiffUtil.getTreeId(rw, key.aCommit());
ObjectId bTree = DiffUtil.getTreeId(rw, key.bCommit());
GitModifiedFilesCacheKey gitKey =
GitModifiedFilesCacheKey.builder()
.project(key.project())
.aTree(aTree)
.bTree(bTree)
.renameScore(key.renameScore())
.build();
List<ModifiedFile> modifiedFiles = mergeRewrittenEntries(gitCache.get(gitKey));
if (key.aCommit().equals(ObjectId.zeroId())) {
return ImmutableList.copyOf(modifiedFiles);
}
RevCommit revCommitA = DiffUtil.getRevCommit(rw, key.aCommit());
RevCommit revCommitB = DiffUtil.getRevCommit(rw, key.bCommit());
if (DiffUtil.areRelated(revCommitA, revCommitB)) {
return ImmutableList.copyOf(modifiedFiles);
}
Set<String> touchedFiles =
getTouchedFilesWithParents(
key, revCommitA.getParent(0).getId(), revCommitB.getParent(0).getId(), rw);
return modifiedFiles.stream()
.filter(f -> isTouched(touchedFiles, f))
.collect(toImmutableList());
}
/**
* Returns the paths of files that were modified between the old and new commits versus their
* parents (i.e. old commit vs. its parent, and new commit vs. its parent).
*
* @param key the {@link ModifiedFilesCacheKey} representing the commits we are diffing
* @param rw a {@link RevWalk} for the repository
* @return The list of modified files between the old/new commits and their parents
*/
private Set<String> getTouchedFilesWithParents(
ModifiedFilesCacheKey key, ObjectId parentOfA, ObjectId parentOfB, RevWalk rw)
throws IOException {
try {
// TODO(ghareeb): as an enhancement: the 3 calls of the underlying git cache can be combined
GitModifiedFilesCacheKey oldVsBaseKey =
GitModifiedFilesCacheKey.create(
key.project(), parentOfA, key.aCommit(), key.renameScore(), rw);
List<ModifiedFile> oldVsBase = gitCache.get(oldVsBaseKey);
GitModifiedFilesCacheKey newVsBaseKey =
GitModifiedFilesCacheKey.create(
key.project(), parentOfB, key.bCommit(), key.renameScore(), rw);
List<ModifiedFile> newVsBase = gitCache.get(newVsBaseKey);
return Sets.union(getOldAndNewPaths(oldVsBase), getOldAndNewPaths(newVsBase));
} catch (DiffNotAvailableException e) {
logger.atWarning().log(
"Failed to retrieve the touched files' commits (%s, %s) and parents (%s, %s): %s",
key.aCommit(), key.bCommit(), parentOfA, parentOfB, e.getMessage());
return ImmutableSet.of();
}
}
private ImmutableSet<String> getOldAndNewPaths(List<ModifiedFile> files) {
return files.stream()
.flatMap(
file -> Stream.concat(Streams.stream(file.oldPath()), Streams.stream(file.newPath())))
.collect(ImmutableSet.toImmutableSet());
}
private static boolean isTouched(Set<String> touchedFilePaths, ModifiedFile modifiedFile) {
String oldFilePath = modifiedFile.oldPath().orElse(null);
String newFilePath = modifiedFile.newPath().orElse(null);
// One of the above file paths could be /dev/null but we need not explicitly check for this
// value as the set of file paths shouldn't contain it.
return touchedFilePaths.contains(oldFilePath) || touchedFilePaths.contains(newFilePath);
}
/**
* Return the {@code modifiedFiles} input list while merging rewritten entries.
*
* <p>Background: In some cases, JGit returns two diff entries (ADDED/DELETED, RENAMED/DELETED,
* etc...) for the same file path. This happens e.g. when a file's mode is changed between
* patchsets, for example converting a symlink file to a regular file. We identify this case and
* return a single modified file with changeType = {@link ChangeType#REWRITE}.
*/
private static List<ModifiedFile> mergeRewrittenEntries(List<ModifiedFile> modifiedFiles) {
List<ModifiedFile> result = new ArrayList<>();
ListMultimap<String, ModifiedFile> byPath = ArrayListMultimap.create();
modifiedFiles.stream()
.forEach(
f -> {
if (f.changeType() == ChangeType.DELETED) {
byPath.get(f.oldPath().get()).add(f);
} else {
byPath.get(f.newPath().get()).add(f);
}
});
for (String path : byPath.keySet()) {
List<ModifiedFile> entries = byPath.get(path);
if (entries.size() == 1) {
result.add(entries.get(0));
} else {
// More than one. Return a single REWRITE entry.
result.add(entries.get(0).toBuilder().changeType(ChangeType.REWRITE).build());
}
}
return result;
}
}
}
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