299 lines
9.4 KiB
Java
299 lines
9.4 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.tomcat.dbcp.pool2.impl;
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import java.io.PrintWriter;
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import java.util.Deque;
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import org.apache.tomcat.dbcp.pool2.PooledObject;
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import org.apache.tomcat.dbcp.pool2.PooledObjectState;
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import org.apache.tomcat.dbcp.pool2.TrackedUse;
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/**
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* This wrapper is used to track the additional information, such as state, for
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* the pooled objects.
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* <p>
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* This class is intended to be thread-safe.
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* </p>
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*
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* @param <T> the type of object in the pool
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*
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* @since 2.0
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*/
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public class DefaultPooledObject<T> implements PooledObject<T> {
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private final T object;
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private PooledObjectState state = PooledObjectState.IDLE; // @GuardedBy("this") to ensure transitions are valid
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private final long createTime = System.currentTimeMillis();
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private volatile long lastBorrowTime = createTime;
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private volatile long lastUseTime = createTime;
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private volatile long lastReturnTime = createTime;
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private volatile boolean logAbandoned = false;
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private volatile CallStack borrowedBy = NoOpCallStack.INSTANCE;
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private volatile CallStack usedBy = NoOpCallStack.INSTANCE;
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private volatile long borrowedCount = 0;
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/**
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* Creates a new instance that wraps the provided object so that the pool can
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* track the state of the pooled object.
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*
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* @param object The object to wrap
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*/
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public DefaultPooledObject(final T object) {
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this.object = object;
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}
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@Override
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public T getObject() {
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return object;
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}
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@Override
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public long getCreateTime() {
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return createTime;
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}
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@Override
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public long getActiveTimeMillis() {
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// Take copies to avoid threading issues
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final long rTime = lastReturnTime;
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final long bTime = lastBorrowTime;
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if (rTime > bTime) {
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return rTime - bTime;
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}
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return System.currentTimeMillis() - bTime;
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}
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@Override
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public long getIdleTimeMillis() {
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final long elapsed = System.currentTimeMillis() - lastReturnTime;
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// elapsed may be negative if:
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// - another thread updates lastReturnTime during the calculation window
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// - System.currentTimeMillis() is not monotonic (e.g. system time is set back)
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return elapsed >= 0 ? elapsed : 0;
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}
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@Override
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public long getLastBorrowTime() {
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return lastBorrowTime;
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}
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@Override
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public long getLastReturnTime() {
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return lastReturnTime;
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}
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/**
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* Gets the number of times this object has been borrowed.
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* @return The number of times this object has been borrowed.
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* @since 2.1
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*/
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@Override
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public long getBorrowedCount() {
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return borrowedCount;
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}
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/**
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* Returns an estimate of the last time this object was used. If the class
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* of the pooled object implements {@link TrackedUse}, what is returned is
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* the maximum of {@link TrackedUse#getLastUsed()} and
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* {@link #getLastBorrowTime()}; otherwise this method gives the same
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* value as {@link #getLastBorrowTime()}.
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*
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* @return the last time this object was used
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*/
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@Override
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public long getLastUsedTime() {
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if (object instanceof TrackedUse) {
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return Math.max(((TrackedUse) object).getLastUsed(), lastUseTime);
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}
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return lastUseTime;
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}
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@Override
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public int compareTo(final PooledObject<T> other) {
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final long lastActiveDiff = this.getLastReturnTime() - other.getLastReturnTime();
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if (lastActiveDiff == 0) {
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// Make sure the natural ordering is broadly consistent with equals
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// although this will break down if distinct objects have the same
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// identity hash code.
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// see java.lang.Comparable Javadocs
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return System.identityHashCode(this) - System.identityHashCode(other);
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}
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// handle int overflow
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return (int)Math.min(Math.max(lastActiveDiff, Integer.MIN_VALUE), Integer.MAX_VALUE);
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}
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@Override
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public String toString() {
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final StringBuilder result = new StringBuilder();
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result.append("Object: ");
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result.append(object.toString());
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result.append(", State: ");
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synchronized (this) {
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result.append(state.toString());
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}
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return result.toString();
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// TODO add other attributes
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}
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@Override
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public synchronized boolean startEvictionTest() {
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if (state == PooledObjectState.IDLE) {
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state = PooledObjectState.EVICTION;
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return true;
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}
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return false;
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}
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@Override
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public synchronized boolean endEvictionTest(
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final Deque<PooledObject<T>> idleQueue) {
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if (state == PooledObjectState.EVICTION) {
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state = PooledObjectState.IDLE;
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return true;
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} else if (state == PooledObjectState.EVICTION_RETURN_TO_HEAD) {
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state = PooledObjectState.IDLE;
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if (!idleQueue.offerFirst(this)) {
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// TODO - Should never happen
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}
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}
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return false;
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}
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/**
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* Allocates the object.
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*
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* @return {@code true} if the original state was {@link PooledObjectState#IDLE IDLE}
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*/
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@Override
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public synchronized boolean allocate() {
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if (state == PooledObjectState.IDLE) {
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state = PooledObjectState.ALLOCATED;
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lastBorrowTime = System.currentTimeMillis();
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lastUseTime = lastBorrowTime;
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borrowedCount++;
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if (logAbandoned) {
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borrowedBy.fillInStackTrace();
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}
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return true;
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} else if (state == PooledObjectState.EVICTION) {
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// TODO Allocate anyway and ignore eviction test
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state = PooledObjectState.EVICTION_RETURN_TO_HEAD;
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return false;
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}
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// TODO if validating and testOnBorrow == true then pre-allocate for
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// performance
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return false;
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}
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/**
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* Deallocates the object and sets it {@link PooledObjectState#IDLE IDLE}
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* if it is currently {@link PooledObjectState#ALLOCATED ALLOCATED}.
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*
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* @return {@code true} if the state was {@link PooledObjectState#ALLOCATED ALLOCATED}
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*/
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@Override
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public synchronized boolean deallocate() {
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if (state == PooledObjectState.ALLOCATED ||
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state == PooledObjectState.RETURNING) {
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state = PooledObjectState.IDLE;
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lastReturnTime = System.currentTimeMillis();
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borrowedBy.clear();
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return true;
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}
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return false;
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}
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/**
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* Sets the state to {@link PooledObjectState#INVALID INVALID}
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*/
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@Override
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public synchronized void invalidate() {
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state = PooledObjectState.INVALID;
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}
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@Override
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public void use() {
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lastUseTime = System.currentTimeMillis();
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usedBy.fillInStackTrace();
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}
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@Override
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public void printStackTrace(final PrintWriter writer) {
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boolean written = borrowedBy.printStackTrace(writer);
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written |= usedBy.printStackTrace(writer);
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if (written) {
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writer.flush();
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}
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}
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/**
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* Returns the state of this object.
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* @return state
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*/
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@Override
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public synchronized PooledObjectState getState() {
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return state;
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}
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/**
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* Marks the pooled object as abandoned.
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*/
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@Override
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public synchronized void markAbandoned() {
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state = PooledObjectState.ABANDONED;
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}
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/**
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* Marks the object as returning to the pool.
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*/
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@Override
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public synchronized void markReturning() {
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state = PooledObjectState.RETURNING;
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}
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@Override
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public void setLogAbandoned(final boolean logAbandoned) {
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this.logAbandoned = logAbandoned;
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}
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/**
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* Configures the stack trace generation strategy based on whether or not fully
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* detailed stack traces are required. When set to false, abandoned logs may
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* only include caller class information rather than method names, line numbers,
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* and other normal metadata available in a full stack trace.
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*
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* @param requireFullStackTrace the new configuration setting for abandoned object
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* logging
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* @since 2.5
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*/
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@Override
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public void setRequireFullStackTrace(final boolean requireFullStackTrace) {
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borrowedBy = CallStackUtils.newCallStack("'Pooled object created' " +
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"yyyy-MM-dd HH:mm:ss Z 'by the following code has not been returned to the pool:'",
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true, requireFullStackTrace);
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usedBy = CallStackUtils.newCallStack("The last code to use this object was:",
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false, requireFullStackTrace);
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}
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}
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