001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.named.ipc;
020
021import javax.inject.Inject;
022import javax.inject.Named;
023import javax.inject.Singleton;
024
025import java.nio.file.Path;
026import java.nio.file.Paths;
027import java.util.Collection;
028import java.util.stream.Collectors;
029
030import org.eclipse.aether.named.NamedLock;
031import org.eclipse.aether.named.NamedLockKey;
032import org.eclipse.aether.named.support.NamedLockFactorySupport;
033import org.eclipse.aether.named.support.NamedLockSupport;
034import org.eclipse.aether.util.StringDigestUtil;
035
036import static java.util.Objects.requireNonNull;
037
038/**
039 * IPC named locks factory.
040 *
041 * @since 2.0.1
042 */
043@Singleton
044@Named(IpcNamedLockFactory.NAME)
045public class IpcNamedLockFactory extends NamedLockFactorySupport {
046    public static final String NAME = "ipc";
047
048    protected final IpcClient client;
049
050    @Inject
051    public IpcNamedLockFactory() {
052        this(Paths.get(System.getProperty("user.home")).resolve(".ipc-sync"));
053    }
054
055    public IpcNamedLockFactory(Path ipcHome) {
056        requireNonNull(ipcHome);
057        Path repository = ipcHome.resolve("repository");
058        Path logPath = ipcHome.resolve("log");
059        this.client = new IpcClient(repository, logPath, null);
060    }
061
062    @Override
063    protected NamedLock doGetLock(Collection<NamedLockKey> keys) {
064        NamedLockKey key = NamedLockKey.of(
065                digestKeys(keys),
066                keys.stream()
067                        .map(NamedLockKey::resources)
068                        .flatMap(Collection::stream)
069                        .collect(Collectors.toList()));
070        return getLockAndRefTrack(
071                key,
072                () -> new IpcNamedLock(
073                        key, this, client, keys.stream().map(NamedLockKey::name).collect(Collectors.toList())));
074    }
075
076    /**
077     * Computes the digest identifying given (ordered) collection of lock keys. The encoding is unambiguous —
078     * netstring-like, the key count followed by each name length-prefixed — so distinct key collections always
079     * yield distinct digests. Plainly concatenating the names would give boundary-shifted collections (for
080     * example {@code ["foo", "bar"]} vs {@code ["foob", "ar"]} — and lock names embed wire-supplied artifact
081     * coordinates) the same digest and hence the same lock identity, letting two racing processes mutate the
082     * same local repository paths while holding what they believe are different locks.
083     */
084    static String digestKeys(Collection<NamedLockKey> keys) {
085        StringDigestUtil sha1 = StringDigestUtil.sha1();
086        sha1.update(keys.size() + ":");
087        for (NamedLockKey key : keys) {
088            String name = key.name();
089            sha1.update(name.length() + ":");
090            sha1.update(name);
091        }
092        return sha1.digest();
093    }
094
095    @Override
096    protected NamedLockSupport createLock(NamedLockKey key) {
097        throw new IllegalStateException("should not get here");
098    }
099
100    @Override
101    protected void doShutdown() {
102        client.close();
103    }
104}