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.support;
020
021import java.util.ArrayDeque;
022import java.util.Collections;
023import java.util.Deque;
024import java.util.Map;
025import java.util.concurrent.ConcurrentHashMap;
026import java.util.concurrent.TimeUnit;
027
028import org.eclipse.aether.named.NamedLock;
029import org.slf4j.Logger;
030import org.slf4j.LoggerFactory;
031
032/**
033 * Support class for {@link NamedLock} implementations providing reference counting.
034 */
035public abstract class NamedLockSupport implements NamedLock {
036    protected final Logger logger = LoggerFactory.getLogger(getClass());
037
038    private final String name;
039
040    private final NamedLockFactorySupport factory;
041
042    private final ConcurrentHashMap<Thread, Deque<String>> diagnosticState; // non-null only if diag enabled
043
044    public NamedLockSupport(final String name, final NamedLockFactorySupport factory) {
045        this.name = name;
046        this.factory = factory;
047        this.diagnosticState = factory.isDiagnosticEnabled() ? new ConcurrentHashMap<>() : null;
048    }
049
050    @Override
051    public String name() {
052        return name;
053    }
054
055    @Override
056    public boolean lockShared(long time, TimeUnit unit) throws InterruptedException {
057        if (diagnosticState != null) {
058            diagnosticState
059                    .computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>())
060                    .push("shared");
061        }
062        return doLockShared(time, unit);
063    }
064
065    protected abstract boolean doLockShared(long time, TimeUnit unit) throws InterruptedException;
066
067    @Override
068    public boolean lockExclusively(long time, TimeUnit unit) throws InterruptedException {
069        if (diagnosticState != null) {
070            diagnosticState
071                    .computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>())
072                    .push("exclusive");
073        }
074        return doLockExclusively(time, unit);
075    }
076
077    protected abstract boolean doLockExclusively(long time, TimeUnit unit) throws InterruptedException;
078
079    @Override
080    public void unlock() {
081        doUnlock();
082        if (diagnosticState != null) {
083            diagnosticState
084                    .computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>())
085                    .pop();
086        }
087    }
088
089    protected abstract void doUnlock();
090
091    @Override
092    public void close() {
093        doClose();
094    }
095
096    protected void doClose() {
097        factory.closeLock(name);
098    }
099
100    /**
101     * Returns the diagnostic state (if collected) or empty map, never {@code null}.
102     *
103     * @since 1.9.11
104     */
105    public Map<Thread, Deque<String>> diagnosticState() {
106        if (diagnosticState != null) {
107            return diagnosticState;
108        } else {
109            return Collections.emptyMap();
110        }
111    }
112
113    @Override
114    public String toString() {
115        return getClass().getSimpleName() + "{" + "name='" + name + '\'' + '}';
116    }
117}