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/*
* 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.tomcat.dbcp.dbcp2;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import org.apache.tomcat.dbcp.pool2.TrackedUse;
/**
* Tracks db connection usage for recovering and reporting
* abandoned db connections.
*
* The JDBC Connection, Statement, and ResultSet classes
* extend this class.
*
* @author Glenn L. Nielsen
* @since 2.0
*/
public class AbandonedTrace implements TrackedUse {
/** A list of objects created by children of this object */
private final List<WeakReference<AbandonedTrace>> traceList = new ArrayList<>();
/** Last time this connection was used */
private volatile long lastUsed = 0;
/**
* Create a new AbandonedTrace without config and
* without doing abandoned tracing.
*/
public AbandonedTrace() {
init(null);
}
/**
* Construct a new AbandonedTrace with a parent object.
*
* @param parent AbandonedTrace parent object
*/
public AbandonedTrace(AbandonedTrace parent) {
init(parent);
}
/**
* Initialize abandoned tracing for this object.
*
* @param parent AbandonedTrace parent object
*/
private void init(AbandonedTrace parent) {
if (parent != null) {
parent.addTrace(this);
}
}
/**
* Get the last time this object was used in ms.
*
* @return long time in ms
*/
@Override
public long getLastUsed() {
return lastUsed;
}
/**
* Set the time this object was last used to the
* current time in ms.
*/
protected void setLastUsed() {
lastUsed = System.currentTimeMillis();
}
/**
* Set the time in ms this object was last used.
*
* @param time time in ms
*/
protected void setLastUsed(long time) {
lastUsed = time;
}
/**
* Add an object to the list of objects being
* traced.
*
* @param trace AbandonedTrace object to add
*/
protected void addTrace(AbandonedTrace trace) {
synchronized (this.traceList) {
this.traceList.add(new WeakReference<>(trace));
}
setLastUsed();
}
/**
* Clear the list of objects being traced by this
* object.
*/
protected void clearTrace() {
synchronized(this.traceList) {
this.traceList.clear();
}
}
/**
* Get a list of objects being traced by this object.
*
* @return List of objects
*/
protected List<AbandonedTrace> getTrace() {
int size = traceList.size();
if (size == 0) {
return Collections.emptyList();
}
ArrayList<AbandonedTrace> result = new ArrayList<>(size);
synchronized (this.traceList) {
Iterator<WeakReference<AbandonedTrace>> iter = traceList.iterator();
while (iter.hasNext()) {
WeakReference<AbandonedTrace> ref = iter.next();
if (ref.get() == null) {
// Clean-up since we are here anyway
iter.remove();
} else {
result.add(ref.get());
}
}
}
return result;
}
/**
* Remove a child object this object is tracing.
*
* @param trace AbandonedTrace object to remove
*/
protected void removeTrace(AbandonedTrace trace) {
synchronized(this.traceList) {
Iterator<WeakReference<AbandonedTrace>> iter = traceList.iterator();
while (iter.hasNext()) {
WeakReference<AbandonedTrace> ref = iter.next();
if (trace.equals(ref.get())) {
iter.remove();
break;
} else if (ref.get() == null) {
// Clean-up since we are here anyway
iter.remove();
}
}
}
}
}
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