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Groovy: A powerful multi-faceted language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.groovy.parser.antlr4.internal.atnmanager;
import org.antlr.v4.runtime.atn.ATN;
import org.apache.groovy.util.SystemUtil;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* Manage ATN to avoid memory leak
*/
public abstract class AtnManager {
private static final ReentrantReadWriteLock RRWL = new ReentrantReadWriteLock(true);
private static final ReentrantReadWriteLock.WriteLock WRITE_LOCK = RRWL.writeLock();
public static final ReentrantReadWriteLock.ReadLock READ_LOCK = RRWL.readLock();
private static final String DFA_CACHE_THRESHOLD_OPT = "groovy.antlr4.cache.threshold";
private static final long DFA_CACHE_THRESHOLD;
static {
long t = SystemUtil.getLongSafe(DFA_CACHE_THRESHOLD_OPT, 64L);
if (t <= 0) {
t = Long.MAX_VALUE;
}
DFA_CACHE_THRESHOLD = t;
}
public abstract ATN getATN();
protected abstract boolean shouldClearDfaCache();
protected class AtnWrapper {
private final ATN atn;
private final AtomicLong counter = new AtomicLong(0);
public AtnWrapper(ATN atn) {
this.atn = atn;
}
public ATN checkAndClear() {
if (!shouldClearDfaCache()) {
return atn;
}
if (0 != counter.incrementAndGet() % DFA_CACHE_THRESHOLD) {
return atn;
}
WRITE_LOCK.lock();
try {
atn.clearDFA();
} finally {
WRITE_LOCK.unlock();
}
return atn;
}
}
}