com.google.gerrit.server.account.externalids.ExternalIdCacheImpl Maven / Gradle / Ivy
// Copyright (C) 2016 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.account.externalids;
import static com.google.common.collect.ImmutableSetMultimap.toImmutableSetMultimap;
import static java.util.stream.Collectors.toSet;
import com.google.auto.value.AutoValue;
import com.google.common.base.Strings;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.Iterables;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.MultimapBuilder;
import com.google.gerrit.reviewdb.client.Account;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.Collection;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Consumer;
import org.eclipse.jgit.lib.ObjectId;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/** Caches external IDs of all accounts. The external IDs are always loaded from NoteDb. */
@Singleton
class ExternalIdCacheImpl implements ExternalIdCache {
private static final Logger log = LoggerFactory.getLogger(ExternalIdCacheImpl.class);
private final LoadingCache extIdsByAccount;
private final ExternalIdReader externalIdReader;
private final Lock lock;
@Inject
ExternalIdCacheImpl(ExternalIdReader externalIdReader) {
this.extIdsByAccount =
CacheBuilder.newBuilder()
// The cached data is potentially pretty large and we are always only interested
// in the latest value, hence the maximum cache size is set to 1.
// This can lead to extra cache loads in case of the following race:
// 1. thread 1 reads the notes ref at revision A
// 2. thread 2 updates the notes ref to revision B and stores the derived value
// for B in the cache
// 3. thread 1 attempts to read the data for revision A from the cache, and misses
// 4. later threads attempt to read at B
// In this race unneeded reloads are done in step 3 (reload from revision A) and
// step 4 (reload from revision B, because the value for revision B was lost when the
// reload from revision A was done, since the cache can hold only one entry).
// These reloads could be avoided by increasing the cache size to 2. However the race
// window between reading the ref and looking it up in the cache is small so that
// it's rare that this race happens. Therefore it's not worth to double the memory
// usage of this cache, just to avoid this.
.maximumSize(1)
.build(new Loader(externalIdReader));
this.externalIdReader = externalIdReader;
this.lock = new ReentrantLock(true /* fair */);
}
@Override
public void onCreate(ObjectId oldNotesRev, ObjectId newNotesRev, Collection extIds)
throws IOException {
updateCache(
oldNotesRev,
newNotesRev,
m -> {
for (ExternalId extId : extIds) {
extId.checkThatBlobIdIsSet();
m.put(extId.accountId(), extId);
}
});
}
@Override
public void onRemove(ObjectId oldNotesRev, ObjectId newNotesRev, Collection extIds)
throws IOException {
updateCache(
oldNotesRev,
newNotesRev,
m -> {
for (ExternalId extId : extIds) {
m.remove(extId.accountId(), extId);
}
});
}
@Override
public void onUpdate(
ObjectId oldNotesRev, ObjectId newNotesRev, Collection updatedExtIds)
throws IOException {
updateCache(
oldNotesRev,
newNotesRev,
m -> {
removeKeys(m.values(), updatedExtIds.stream().map(e -> e.key()).collect(toSet()));
for (ExternalId updatedExtId : updatedExtIds) {
updatedExtId.checkThatBlobIdIsSet();
m.put(updatedExtId.accountId(), updatedExtId);
}
});
}
@Override
public void onReplace(
ObjectId oldNotesRev,
ObjectId newNotesRev,
Account.Id accountId,
Collection toRemove,
Collection toAdd)
throws IOException {
ExternalIdsUpdate.checkSameAccount(Iterables.concat(toRemove, toAdd), accountId);
updateCache(
oldNotesRev,
newNotesRev,
m -> {
for (ExternalId extId : toRemove) {
m.remove(extId.accountId(), extId);
}
for (ExternalId extId : toAdd) {
extId.checkThatBlobIdIsSet();
m.put(extId.accountId(), extId);
}
});
}
@Override
public void onReplace(
ObjectId oldNotesRev,
ObjectId newNotesRev,
Collection toRemove,
Collection toAdd)
throws IOException {
updateCache(
oldNotesRev,
newNotesRev,
m -> {
for (ExternalId extId : toRemove) {
m.remove(extId.accountId(), extId);
}
for (ExternalId extId : toAdd) {
extId.checkThatBlobIdIsSet();
m.put(extId.accountId(), extId);
}
});
}
@Override
public ImmutableSet byAccount(Account.Id accountId) throws IOException {
return get().byAccount().get(accountId);
}
@Override
public ImmutableSetMultimap allByAccount() throws IOException {
return get().byAccount();
}
@Override
public ImmutableSetMultimap byEmails(String... emails) throws IOException {
AllExternalIds allExternalIds = get();
ImmutableSetMultimap.Builder byEmails = ImmutableSetMultimap.builder();
for (String email : emails) {
byEmails.putAll(email, allExternalIds.byEmail().get(email));
}
return byEmails.build();
}
@Override
public ImmutableSetMultimap allByEmail() throws IOException {
return get().byEmail();
}
private AllExternalIds get() throws IOException {
try {
return extIdsByAccount.get(externalIdReader.readRevision());
} catch (ExecutionException e) {
throw new IOException("Cannot load external ids", e);
}
}
private void updateCache(
ObjectId oldNotesRev,
ObjectId newNotesRev,
Consumer> update) {
lock.lock();
try {
ListMultimap m;
if (!ObjectId.zeroId().equals(oldNotesRev)) {
m =
MultimapBuilder.hashKeys()
.arrayListValues()
.build(extIdsByAccount.get(oldNotesRev).byAccount());
} else {
m = MultimapBuilder.hashKeys().arrayListValues().build();
}
update.accept(m);
extIdsByAccount.put(newNotesRev, AllExternalIds.create(m));
} catch (ExecutionException e) {
log.warn("Cannot update external IDs", e);
} finally {
lock.unlock();
}
}
private static void removeKeys(Collection ids, Collection toRemove) {
Collections2.transform(ids, e -> e.key()).removeAll(toRemove);
}
private static class Loader extends CacheLoader {
private final ExternalIdReader externalIdReader;
Loader(ExternalIdReader externalIdReader) {
this.externalIdReader = externalIdReader;
}
@Override
public AllExternalIds load(ObjectId notesRev) throws Exception {
Multimap extIdsByAccount =
MultimapBuilder.hashKeys().arrayListValues().build();
for (ExternalId extId : externalIdReader.all(notesRev)) {
extId.checkThatBlobIdIsSet();
extIdsByAccount.put(extId.accountId(), extId);
}
return AllExternalIds.create(extIdsByAccount);
}
}
@AutoValue
abstract static class AllExternalIds {
static AllExternalIds create(Multimap byAccount) {
ImmutableSetMultimap byEmail =
byAccount
.values()
.stream()
.filter(e -> !Strings.isNullOrEmpty(e.email()))
.collect(toImmutableSetMultimap(ExternalId::email, e -> e));
return new AutoValue_ExternalIdCacheImpl_AllExternalIds(
ImmutableSetMultimap.copyOf(byAccount), byEmail);
}
public abstract ImmutableSetMultimap byAccount();
public abstract ImmutableSetMultimap byEmail();
}
}
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