001package org.eclipse.aether.named.support; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import org.eclipse.aether.named.NamedLockFactory; 023import org.slf4j.Logger; 024import org.slf4j.LoggerFactory; 025 026import java.util.concurrent.ConcurrentHashMap; 027import java.util.concurrent.ConcurrentMap; 028import java.util.concurrent.atomic.AtomicBoolean; 029import java.util.concurrent.atomic.AtomicInteger; 030 031/** 032 * Support class for {@link NamedLockFactory} implementations providing reference counting. 033 */ 034public abstract class NamedLockFactorySupport implements NamedLockFactory 035{ 036 protected final Logger logger = LoggerFactory.getLogger( getClass() ); 037 038 private final ConcurrentMap<String, NamedLockHolder> locks; 039 040 public NamedLockFactorySupport() 041 { 042 this.locks = new ConcurrentHashMap<>(); 043 } 044 045 @Override 046 public NamedLockSupport getLock( final String name ) 047 { 048 return locks.compute( name, ( k, v ) -> 049 { 050 if ( v == null ) 051 { 052 v = new NamedLockHolder( createLock( k ) ); 053 } 054 v.incRef(); 055 return v; 056 } ).namedLock; 057 } 058 059 @Override 060 public void shutdown() 061 { 062 // override if needed 063 } 064 065 public boolean closeLock( final NamedLockSupport lock ) 066 { 067 AtomicBoolean destroyed = new AtomicBoolean( false ); 068 locks.compute( lock.name(), ( k, v ) -> 069 { 070 if ( v != null && v.decRef() == 0 ) 071 { 072 destroyLock( v.namedLock ); 073 destroyed.set( true ); 074 return null; 075 } 076 return v; 077 } ); 078 return destroyed.get(); 079 } 080 081 082 @Override 083 protected void finalize() throws Throwable 084 { 085 try 086 { 087 if ( !locks.isEmpty() ) 088 { 089 // report leak 090 logger.warn( "Lock leak, referenced locks still exist {}", locks ); 091 } 092 } 093 finally 094 { 095 super.finalize(); 096 } 097 } 098 099 protected abstract NamedLockSupport createLock( final String name ); 100 101 protected void destroyLock( final NamedLockSupport lock ) 102 { 103 // override if needed 104 } 105 106 private static final class NamedLockHolder 107 { 108 private final NamedLockSupport namedLock; 109 110 private final AtomicInteger referenceCount; 111 112 private NamedLockHolder( NamedLockSupport namedLock ) 113 { 114 this.namedLock = namedLock; 115 this.referenceCount = new AtomicInteger( 0 ); 116 } 117 118 private int incRef() 119 { 120 return referenceCount.incrementAndGet(); 121 } 122 123 private int decRef() 124 { 125 return referenceCount.decrementAndGet(); 126 } 127 128 @Override 129 public String toString() 130 { 131 return "[refCount=" + referenceCount.get() + ", lock=" + namedLock + "]"; 132 } 133 } 134}