001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.pool.impl;
019
020 import java.util.ArrayList;
021 import java.util.Collection;
022 import java.util.Iterator;
023 import java.util.LinkedList;
024 import java.util.List;
025 import java.util.NoSuchElementException;
026 import java.util.TimerTask;
027
028 import org.apache.commons.pool.BaseObjectPool;
029 import org.apache.commons.pool.ObjectPool;
030 import org.apache.commons.pool.PoolableObjectFactory;
031 import org.apache.commons.pool.impl.GenericKeyedObjectPool.ObjectTimestampPair;
032
033 /**
034 * A configurable {@link ObjectPool} implementation.
035 * <p>
036 * When coupled with the appropriate {@link PoolableObjectFactory},
037 * <tt>GenericObjectPool</tt> provides robust pooling functionality for
038 * arbitrary objects.
039 * <p>
040 * A <tt>GenericObjectPool</tt> provides a number of configurable parameters:
041 * <ul>
042 * <li>
043 * {@link #setMaxActive <i>maxActive</i>} controls the maximum number of
044 * objects that can be allocated by the pool (checked out to clients, or
045 * idle awaiting checkout) at a given time. When non-positive, there is no
046 * limit to the number of objects that can be managed by the pool at one time.
047 * When {@link #setMaxActive <i>maxActive</i>} is reached, the pool is said
048 * to be exhausted. The default setting for this parameter is 8.
049 * </li>
050 * <li>
051 * {@link #setMaxIdle <i>maxIdle</i>} controls the maximum number of objects
052 * that can sit idle in the pool at any time. When negative, there is no
053 * limit to the number of objects that may be idle at one time. The default
054 * setting for this parameter is 8.
055 * </li>
056 * <li>
057 * {@link #setWhenExhaustedAction <i>whenExhaustedAction</i>} specifies the
058 * behavior of the {@link #borrowObject} method when the pool is exhausted:
059 * <ul>
060 * <li>
061 * When {@link #setWhenExhaustedAction <i>whenExhaustedAction</i>} is
062 * {@link #WHEN_EXHAUSTED_FAIL}, {@link #borrowObject} will throw
063 * a {@link NoSuchElementException}
064 * </li>
065 * <li>
066 * When {@link #setWhenExhaustedAction <i>whenExhaustedAction</i>} is
067 * {@link #WHEN_EXHAUSTED_GROW}, {@link #borrowObject} will create a new
068 * object and return it (essentially making {@link #setMaxActive <i>maxActive</i>}
069 * meaningless.)
070 * </li>
071 * <li>
072 * When {@link #setWhenExhaustedAction <i>whenExhaustedAction</i>}
073 * is {@link #WHEN_EXHAUSTED_BLOCK}, {@link #borrowObject} will block
074 * (invoke {@link Object#wait()}) until a new or idle object is available.
075 * If a positive {@link #setMaxWait <i>maxWait</i>}
076 * value is supplied, then {@link #borrowObject} will block for at
077 * most that many milliseconds, after which a {@link NoSuchElementException}
078 * will be thrown. If {@link #setMaxWait <i>maxWait</i>} is non-positive,
079 * the {@link #borrowObject} method will block indefinitely.
080 * </li>
081 * </ul>
082 * The default <code>whenExhaustedAction</code> setting is
083 * {@link #WHEN_EXHAUSTED_BLOCK} and the default <code>maxWait</code>
084 * setting is -1. By default, therefore, <code>borrowObject</code> will
085 * block indefinitely until an idle instance becomes available.
086 * </li>
087 * <li>
088 * When {@link #setTestOnBorrow <i>testOnBorrow</i>} is set, the pool will
089 * attempt to validate each object before it is returned from the
090 * {@link #borrowObject} method. (Using the provided factory's
091 * {@link PoolableObjectFactory#validateObject} method.) Objects that fail
092 * to validate will be dropped from the pool, and a different object will
093 * be borrowed. The default setting for this parameter is
094 * <code>false.</code>
095 * </li>
096 * <li>
097 * When {@link #setTestOnReturn <i>testOnReturn</i>} is set, the pool will
098 * attempt to validate each object before it is returned to the pool in the
099 * {@link #returnObject} method. (Using the provided factory's
100 * {@link PoolableObjectFactory#validateObject}
101 * method.) Objects that fail to validate will be dropped from the pool.
102 * The default setting for this parameter is <code>false.</code>
103 * </li>
104 * </ul>
105 * <p>
106 * Optionally, one may configure the pool to examine and possibly evict objects
107 * as they sit idle in the pool and to ensure that a minimum number of idle
108 * objects are available. This is performed by an "idle object eviction"
109 * thread, which runs asynchronously. Caution should be used when configuring
110 * this optional feature. Eviction runs require an exclusive synchronization
111 * lock on the pool, so if they run too frequently and / or incur excessive
112 * latency when creating, destroying or validating object instances,
113 * performance issues may result. The idle object eviction thread may be
114 * configured using the following attributes:
115 * <ul>
116 * <li>
117 * {@link #setTimeBetweenEvictionRunsMillis <i>timeBetweenEvictionRunsMillis</i>}
118 * indicates how long the eviction thread should sleep before "runs" of examining
119 * idle objects. When non-positive, no eviction thread will be launched. The
120 * default setting for this parameter is -1 (i.e., idle object eviction is
121 * disabled by default).
122 * </li>
123 * <li>
124 * {@link #setMinEvictableIdleTimeMillis <i>minEvictableIdleTimeMillis</i>}
125 * specifies the minimum amount of time that an object may sit idle in the pool
126 * before it is eligible for eviction due to idle time. When non-positive, no object
127 * will be dropped from the pool due to idle time alone. This setting has no
128 * effect unless <code>timeBetweenEvictionRunsMillis > 0.</code> The default
129 * setting for this parameter is 30 minutes.
130 * </li>
131 * <li>
132 * {@link #setTestWhileIdle <i>testWhileIdle</i>} indicates whether or not idle
133 * objects should be validated using the factory's
134 * {@link PoolableObjectFactory#validateObject} method. Objects that fail to
135 * validate will be dropped from the pool. This setting has no effect unless
136 * <code>timeBetweenEvictionRunsMillis > 0.</code> The default setting for
137 * this parameter is <code>false.</code>
138 * </li>
139 * <li>
140 * {@link #setSoftMinEvictableIdleTimeMillis <i>softMinEvictableIdleTimeMillis</i>}
141 * specifies the minimum amount of time an object may sit idle in the pool
142 * before it is eligible for eviction by the idle object evictor
143 * (if any), with the extra condition that at least "minIdle" object instances
144 * remain in the pool. When non-positive, no objects will be evicted from the pool
145 * due to idle time alone. This setting has no effect unless
146 * <code>timeBetweenEvictionRunsMillis > 0.</code> and it is superceded by
147 * {@link #setMinEvictableIdleTimeMillis <i>minEvictableIdleTimeMillis</i>}
148 * (that is, if <code>minEvictableIdleTimeMillis</code> is positive, then
149 * <code>softMinEvictableIdleTimeMillis</code> is ignored). The default setting for
150 * this parameter is -1 (disabled).
151 * </li>
152 * <li>
153 * {@link #setNumTestsPerEvictionRun <i>numTestsPerEvictionRun</i>}
154 * determines the number of objects examined in each run of the idle object
155 * evictor. This setting has no effect unless
156 * <code>timeBetweenEvictionRunsMillis > 0.</code> The default setting for
157 * this parameter is 3.
158 * </li>
159 * </ul>
160 * <p>
161 * <p>
162 * The pool can be configured to behave as a LIFO queue with respect to idle
163 * objects - always returning the most recently used object from the pool,
164 * or as a FIFO queue, where borrowObject always returns the oldest object
165 * in the idle object pool.
166 * <ul>
167 * <li>
168 * {@link #setLifo <i>lifo</i>}
169 * determines whether or not the pool returns idle objects in
170 * last-in-first-out order. The default setting for this parameter is
171 * <code>true.</code>
172 * </li>
173 * </ul>
174 * <p>
175 * GenericObjectPool is not usable without a {@link PoolableObjectFactory}. A
176 * non-<code>null</code> factory must be provided either as a constructor argument
177 * or via a call to {@link #setFactory} before the pool is used.
178 * <p>
179 * Implementation note: To prevent possible deadlocks, care has been taken to
180 * ensure that no call to a factory method will occur within a synchronization
181 * block. See POOL-125 and DBCP-44 for more information.
182 *
183 * @see GenericKeyedObjectPool
184 * @author Rodney Waldhoff
185 * @author Dirk Verbeeck
186 * @author Sandy McArthur
187 * @version $Revision: 784441 $ $Date: 2009-06-13 13:42:28 -0400 (Sat, 13 Jun 2009) $
188 * @since Pool 1.0
189 */
190 public class GenericObjectPool extends BaseObjectPool implements ObjectPool {
191
192 //--- public constants -------------------------------------------
193
194 /**
195 * A "when exhausted action" type indicating that when the pool is
196 * exhausted (i.e., the maximum number of active objects has
197 * been reached), the {@link #borrowObject}
198 * method should fail, throwing a {@link NoSuchElementException}.
199 * @see #WHEN_EXHAUSTED_BLOCK
200 * @see #WHEN_EXHAUSTED_GROW
201 * @see #setWhenExhaustedAction
202 */
203 public static final byte WHEN_EXHAUSTED_FAIL = 0;
204
205 /**
206 * A "when exhausted action" type indicating that when the pool
207 * is exhausted (i.e., the maximum number
208 * of active objects has been reached), the {@link #borrowObject}
209 * method should block until a new object is available, or the
210 * {@link #getMaxWait maximum wait time} has been reached.
211 * @see #WHEN_EXHAUSTED_FAIL
212 * @see #WHEN_EXHAUSTED_GROW
213 * @see #setMaxWait
214 * @see #getMaxWait
215 * @see #setWhenExhaustedAction
216 */
217 public static final byte WHEN_EXHAUSTED_BLOCK = 1;
218
219 /**
220 * A "when exhausted action" type indicating that when the pool is
221 * exhausted (i.e., the maximum number
222 * of active objects has been reached), the {@link #borrowObject}
223 * method should simply create a new object anyway.
224 * @see #WHEN_EXHAUSTED_FAIL
225 * @see #WHEN_EXHAUSTED_GROW
226 * @see #setWhenExhaustedAction
227 */
228 public static final byte WHEN_EXHAUSTED_GROW = 2;
229
230 /**
231 * The default cap on the number of "sleeping" instances in the pool.
232 * @see #getMaxIdle
233 * @see #setMaxIdle
234 */
235 public static final int DEFAULT_MAX_IDLE = 8;
236
237 /**
238 * The default minimum number of "sleeping" instances in the pool
239 * before before the evictor thread (if active) spawns new objects.
240 * @see #getMinIdle
241 * @see #setMinIdle
242 */
243 public static final int DEFAULT_MIN_IDLE = 0;
244
245 /**
246 * The default cap on the total number of active instances from the pool.
247 * @see #getMaxActive
248 */
249 public static final int DEFAULT_MAX_ACTIVE = 8;
250
251 /**
252 * The default "when exhausted action" for the pool.
253 * @see #WHEN_EXHAUSTED_BLOCK
254 * @see #WHEN_EXHAUSTED_FAIL
255 * @see #WHEN_EXHAUSTED_GROW
256 * @see #setWhenExhaustedAction
257 */
258 public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION = WHEN_EXHAUSTED_BLOCK;
259
260 /**
261 * The default LIFO status. True means that borrowObject returns the
262 * most recently used ("last in") idle object in the pool (if there are
263 * idle instances available). False means that the pool behaves as a FIFO
264 * queue - objects are taken from the idle object pool in the order that
265 * they are returned to the pool.
266 * @see #setLifo
267 * @since 1.4
268 */
269 public static final boolean DEFAULT_LIFO = true;
270
271 /**
272 * The default maximum amount of time (in milliseconds) the
273 * {@link #borrowObject} method should block before throwing
274 * an exception when the pool is exhausted and the
275 * {@link #getWhenExhaustedAction "when exhausted" action} is
276 * {@link #WHEN_EXHAUSTED_BLOCK}.
277 * @see #getMaxWait
278 * @see #setMaxWait
279 */
280 public static final long DEFAULT_MAX_WAIT = -1L;
281
282 /**
283 * The default "test on borrow" value.
284 * @see #getTestOnBorrow
285 * @see #setTestOnBorrow
286 */
287 public static final boolean DEFAULT_TEST_ON_BORROW = false;
288
289 /**
290 * The default "test on return" value.
291 * @see #getTestOnReturn
292 * @see #setTestOnReturn
293 */
294 public static final boolean DEFAULT_TEST_ON_RETURN = false;
295
296 /**
297 * The default "test while idle" value.
298 * @see #getTestWhileIdle
299 * @see #setTestWhileIdle
300 * @see #getTimeBetweenEvictionRunsMillis
301 * @see #setTimeBetweenEvictionRunsMillis
302 */
303 public static final boolean DEFAULT_TEST_WHILE_IDLE = false;
304
305 /**
306 * The default "time between eviction runs" value.
307 * @see #getTimeBetweenEvictionRunsMillis
308 * @see #setTimeBetweenEvictionRunsMillis
309 */
310 public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS = -1L;
311
312 /**
313 * The default number of objects to examine per run in the
314 * idle object evictor.
315 * @see #getNumTestsPerEvictionRun
316 * @see #setNumTestsPerEvictionRun
317 * @see #getTimeBetweenEvictionRunsMillis
318 * @see #setTimeBetweenEvictionRunsMillis
319 */
320 public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;
321
322 /**
323 * The default value for {@link #getMinEvictableIdleTimeMillis}.
324 * @see #getMinEvictableIdleTimeMillis
325 * @see #setMinEvictableIdleTimeMillis
326 */
327 public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS = 1000L * 60L * 30L;
328
329 /**
330 * The default value for {@link #getSoftMinEvictableIdleTimeMillis}.
331 * @see #getSoftMinEvictableIdleTimeMillis
332 * @see #setSoftMinEvictableIdleTimeMillis
333 */
334 public static final long DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS = -1;
335
336 //--- constructors -----------------------------------------------
337
338 /**
339 * Create a new <tt>GenericObjectPool</tt> with default properties.
340 */
341 public GenericObjectPool() {
342 this(null, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
343 DEFAULT_MIN_IDLE, DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
344 DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
345 }
346
347 /**
348 * Create a new <tt>GenericObjectPool</tt> using the specified factory.
349 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
350 */
351 public GenericObjectPool(PoolableObjectFactory factory) {
352 this(factory, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
353 DEFAULT_MIN_IDLE, DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
354 DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
355 }
356
357 /**
358 * Create a new <tt>GenericObjectPool</tt> using the specified values.
359 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
360 * @param config a non-<tt>null</tt> {@link GenericObjectPool.Config} describing my configuration
361 */
362 public GenericObjectPool(PoolableObjectFactory factory, GenericObjectPool.Config config) {
363 this(factory, config.maxActive, config.whenExhaustedAction, config.maxWait, config.maxIdle, config.minIdle,
364 config.testOnBorrow, config.testOnReturn, config.timeBetweenEvictionRunsMillis,
365 config.numTestsPerEvictionRun, config.minEvictableIdleTimeMillis, config.testWhileIdle,
366 config.softMinEvictableIdleTimeMillis, config.lifo);
367 }
368
369 /**
370 * Create a new <tt>GenericObjectPool</tt> using the specified values.
371 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
372 * @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
373 */
374 public GenericObjectPool(PoolableObjectFactory factory, int maxActive) {
375 this(factory, maxActive, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE, DEFAULT_MIN_IDLE,
376 DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
377 DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
378 }
379
380 /**
381 * Create a new <tt>GenericObjectPool</tt> using the specified values.
382 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
383 * @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
384 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
385 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and
386 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
387 */
388 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait) {
389 this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE, DEFAULT_MIN_IDLE, DEFAULT_TEST_ON_BORROW,
390 DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
391 DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
392 }
393
394 /**
395 * Create a new <tt>GenericObjectPool</tt> using the specified values.
396 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
397 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
398 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
399 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and
400 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
401 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method
402 * (see {@link #getTestOnBorrow})
403 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method
404 * (see {@link #getTestOnReturn})
405 */
406 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
407 boolean testOnBorrow, boolean testOnReturn) {
408 this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE, DEFAULT_MIN_IDLE, testOnBorrow,
409 testOnReturn, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
410 DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
411 }
412
413 /**
414 * Create a new <tt>GenericObjectPool</tt> using the specified values.
415 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
416 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
417 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
418 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
419 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
420 * @param maxIdle the maximum number of idle objects in my pool (see {@link #getMaxIdle})
421 */
422 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle) {
423 this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_MIN_IDLE, DEFAULT_TEST_ON_BORROW,
424 DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
425 DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
426 }
427
428 /**
429 * Create a new <tt>GenericObjectPool</tt> using the specified values.
430 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
431 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
432 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
433 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
434 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
435 * @param maxIdle the maximum number of idle objects in my pool (see {@link #getMaxIdle})
436 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method
437 * (see {@link #getTestOnBorrow})
438 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method
439 * (see {@link #getTestOnReturn})
440 */
441 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
442 int maxIdle, boolean testOnBorrow, boolean testOnReturn) {
443 this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_MIN_IDLE, testOnBorrow, testOnReturn,
444 DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
445 DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
446 }
447
448 /**
449 * Create a new <tt>GenericObjectPool</tt> using the specified values.
450 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
451 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
452 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
453 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
454 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
455 * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
456 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
457 * method (see {@link #setTestOnBorrow})
458 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method
459 * (see {@link #setTestOnReturn})
460 * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects
461 * for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
462 * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread
463 * (if any) (see {@link #setNumTestsPerEvictionRun})
464 * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it
465 * is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
466 * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
467 * (see {@link #setTestWhileIdle})
468 */
469 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
470 int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
471 int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
472 this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_MIN_IDLE, testOnBorrow, testOnReturn,
473 timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle);
474 }
475
476 /**
477 * Create a new <tt>GenericObjectPool</tt> using the specified values.
478 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
479 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
480 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
481 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
482 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
483 * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
484 * @param minIdle the minimum number of idle objects in my pool (see {@link #setMinIdle})
485 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method
486 * (see {@link #setTestOnBorrow})
487 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method
488 * (see {@link #setTestOnReturn})
489 * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects
490 * for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
491 * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread
492 * (if any) (see {@link #setNumTestsPerEvictionRun})
493 * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
494 * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
495 * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
496 * (see {@link #setTestWhileIdle})
497 */
498 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
499 int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
500 int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
501 this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, minIdle, testOnBorrow, testOnReturn,
502 timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
503 DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS);
504 }
505
506 /**
507 * Create a new <tt>GenericObjectPool</tt> using the specified values.
508 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
509 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
510 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
511 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
512 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
513 * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
514 * @param minIdle the minimum number of idle objects in my pool (see {@link #setMinIdle})
515 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
516 * method (see {@link #setTestOnBorrow})
517 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
518 * method (see {@link #setTestOnReturn})
519 * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects
520 * for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
521 * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread
522 * (if any) (see {@link #setNumTestsPerEvictionRun})
523 * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
524 * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
525 * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
526 * (see {@link #setTestWhileIdle})
527 * @param softMinEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is
528 * eligible for eviction with the extra condition that at least "minIdle" amount of object remain in the pool.
529 * (see {@link #setSoftMinEvictableIdleTimeMillis})
530 * @since Pool 1.3
531 */
532 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
533 int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
534 int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle,
535 long softMinEvictableIdleTimeMillis) {
536 this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, minIdle, testOnBorrow, testOnReturn,
537 timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
538 softMinEvictableIdleTimeMillis, DEFAULT_LIFO);
539 }
540
541 /**
542 * Create a new <tt>GenericObjectPool</tt> using the specified values.
543 * @param factory the (possibly <tt>null</tt>)PoolableObjectFactory to use to create, validate and destroy objects
544 * @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
545 * @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
546 * @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
547 * <i>whenExhaustedAction</i> is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
548 * @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
549 * @param minIdle the minimum number of idle objects in my pool (see {@link #setMinIdle})
550 * @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
551 * method (see {@link #setTestOnBorrow})
552 * @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
553 * method (see {@link #setTestOnReturn})
554 * @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
555 * objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
556 * @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
557 * thread (if any) (see {@link #setNumTestsPerEvictionRun})
558 * @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
559 * it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
560 * @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
561 * (see {@link #setTestWhileIdle})
562 * @param softMinEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the
563 * pool before it is eligible for eviction with the extra condition that at least "minIdle" amount of object
564 * remain in the pool. (see {@link #setSoftMinEvictableIdleTimeMillis})
565 * @param lifo whether or not objects are returned in last-in-first-out order from the idle object pool
566 * (see {@link #setLifo})
567 * @since Pool 1.4
568 */
569 public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait,
570 int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
571 int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle,
572 long softMinEvictableIdleTimeMillis, boolean lifo) {
573 _factory = factory;
574 _maxActive = maxActive;
575 _lifo = lifo;
576 switch(whenExhaustedAction) {
577 case WHEN_EXHAUSTED_BLOCK:
578 case WHEN_EXHAUSTED_FAIL:
579 case WHEN_EXHAUSTED_GROW:
580 _whenExhaustedAction = whenExhaustedAction;
581 break;
582 default:
583 throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
584 }
585 _maxWait = maxWait;
586 _maxIdle = maxIdle;
587 _minIdle = minIdle;
588 _testOnBorrow = testOnBorrow;
589 _testOnReturn = testOnReturn;
590 _timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
591 _numTestsPerEvictionRun = numTestsPerEvictionRun;
592 _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
593 _softMinEvictableIdleTimeMillis = softMinEvictableIdleTimeMillis;
594 _testWhileIdle = testWhileIdle;
595
596 _pool = new CursorableLinkedList();
597 startEvictor(_timeBetweenEvictionRunsMillis);
598 }
599
600 //--- public methods ---------------------------------------------
601
602 //--- configuration methods --------------------------------------
603
604 /**
605 * Returns the maximum number of objects that can be allocated by the pool
606 * (checked out to clients, or idle awaiting checkout) at a given time.
607 * When non-positive, there is no limit to the number of objects that can
608 * be managed by the pool at one time.
609 *
610 * @return the cap on the total number of object instances managed by the pool.
611 * @see #setMaxActive
612 */
613 public synchronized int getMaxActive() {
614 return _maxActive;
615 }
616
617 /**
618 * Sets the cap on the number of objects that can be allocated by the pool
619 * (checked out to clients, or idle awaiting checkout) at a given time. Use
620 * a negative value for no limit.
621 *
622 * @param maxActive The cap on the total number of object instances managed by the pool.
623 * Negative values mean that there is no limit to the number of objects allocated
624 * by the pool.
625 * @see #getMaxActive
626 */
627 public synchronized void setMaxActive(int maxActive) {
628 _maxActive = maxActive;
629 allocate();
630 }
631
632 /**
633 * Returns the action to take when the {@link #borrowObject} method
634 * is invoked when the pool is exhausted (the maximum number
635 * of "active" objects has been reached).
636 *
637 * @return one of {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL} or {@link #WHEN_EXHAUSTED_GROW}
638 * @see #setWhenExhaustedAction
639 */
640 public synchronized byte getWhenExhaustedAction() {
641 return _whenExhaustedAction;
642 }
643
644 /**
645 * Sets the action to take when the {@link #borrowObject} method
646 * is invoked when the pool is exhausted (the maximum number
647 * of "active" objects has been reached).
648 *
649 * @param whenExhaustedAction the action code, which must be one of
650 * {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL},
651 * or {@link #WHEN_EXHAUSTED_GROW}
652 * @see #getWhenExhaustedAction
653 */
654 public synchronized void setWhenExhaustedAction(byte whenExhaustedAction) {
655 switch(whenExhaustedAction) {
656 case WHEN_EXHAUSTED_BLOCK:
657 case WHEN_EXHAUSTED_FAIL:
658 case WHEN_EXHAUSTED_GROW:
659 _whenExhaustedAction = whenExhaustedAction;
660 allocate();
661 break;
662 default:
663 throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
664 }
665 }
666
667
668 /**
669 * Returns the maximum amount of time (in milliseconds) the
670 * {@link #borrowObject} method should block before throwing
671 * an exception when the pool is exhausted and the
672 * {@link #setWhenExhaustedAction "when exhausted" action} is
673 * {@link #WHEN_EXHAUSTED_BLOCK}.
674 *
675 * When less than or equal to 0, the {@link #borrowObject} method
676 * may block indefinitely.
677 *
678 * @return maximum number of milliseconds to block when borrowing an object.
679 * @see #setMaxWait
680 * @see #setWhenExhaustedAction
681 * @see #WHEN_EXHAUSTED_BLOCK
682 */
683 public synchronized long getMaxWait() {
684 return _maxWait;
685 }
686
687 /**
688 * Sets the maximum amount of time (in milliseconds) the
689 * {@link #borrowObject} method should block before throwing
690 * an exception when the pool is exhausted and the
691 * {@link #setWhenExhaustedAction "when exhausted" action} is
692 * {@link #WHEN_EXHAUSTED_BLOCK}.
693 *
694 * When less than or equal to 0, the {@link #borrowObject} method
695 * may block indefinitely.
696 *
697 * @param maxWait maximum number of milliseconds to block when borrowing an object.
698 * @see #getMaxWait
699 * @see #setWhenExhaustedAction
700 * @see #WHEN_EXHAUSTED_BLOCK
701 */
702 public synchronized void setMaxWait(long maxWait) {
703 _maxWait = maxWait;
704 allocate();
705 }
706
707 /**
708 * Returns the cap on the number of "idle" instances in the pool.
709 * @return the cap on the number of "idle" instances in the pool.
710 * @see #setMaxIdle
711 */
712 public synchronized int getMaxIdle() {
713 return _maxIdle;
714 }
715
716 /**
717 * Sets the cap on the number of "idle" instances in the pool.
718 * If maxIdle is set too low on heavily loaded systems it is possible you
719 * will see objects being destroyed and almost immediately new objects
720 * being created. This is a result of the active threads momentarily
721 * returning objects faster than they are requesting them them, causing the
722 * number of idle objects to rise above maxIdle. The best value for maxIdle
723 * for heavily loaded system will vary but the default is a good starting
724 * point.
725 * @param maxIdle The cap on the number of "idle" instances in the pool.
726 * Use a negative value to indicate an unlimited number of idle instances.
727 * @see #getMaxIdle
728 */
729 public synchronized void setMaxIdle(int maxIdle) {
730 _maxIdle = maxIdle;
731 allocate();
732 }
733
734 /**
735 * Sets the minimum number of objects allowed in the pool
736 * before the evictor thread (if active) spawns new objects.
737 * Note that no objects are created when
738 * <code>numActive + numIdle >= maxActive.</code>
739 * This setting has no effect if the idle object evictor is disabled
740 * (i.e. if <code>timeBetweenEvictionRunsMillis <= 0</code>).
741 *
742 * @param minIdle The minimum number of objects.
743 * @see #getMinIdle
744 * @see #getTimeBetweenEvictionRunsMillis()
745 */
746 public synchronized void setMinIdle(int minIdle) {
747 _minIdle = minIdle;
748 allocate();
749 }
750
751 /**
752 * Returns the minimum number of objects allowed in the pool
753 * before the evictor thread (if active) spawns new objects.
754 * (Note no objects are created when: numActive + numIdle >= maxActive)
755 *
756 * @return The minimum number of objects.
757 * @see #setMinIdle
758 */
759 public synchronized int getMinIdle() {
760 return _minIdle;
761 }
762
763 /**
764 * When <tt>true</tt>, objects will be
765 * {@link PoolableObjectFactory#validateObject validated}
766 * before being returned by the {@link #borrowObject}
767 * method. If the object fails to validate,
768 * it will be dropped from the pool, and we will attempt
769 * to borrow another.
770 *
771 * @return <code>true</code> if objects are validated before being borrowed.
772 * @see #setTestOnBorrow
773 */
774 public boolean getTestOnBorrow() {
775 return _testOnBorrow;
776 }
777
778 /**
779 * When <tt>true</tt>, objects will be
780 * {@link PoolableObjectFactory#validateObject validated}
781 * before being returned by the {@link #borrowObject}
782 * method. If the object fails to validate,
783 * it will be dropped from the pool, and we will attempt
784 * to borrow another.
785 *
786 * @param testOnBorrow <code>true</code> if objects should be validated before being borrowed.
787 * @see #getTestOnBorrow
788 */
789 public void setTestOnBorrow(boolean testOnBorrow) {
790 _testOnBorrow = testOnBorrow;
791 }
792
793 /**
794 * When <tt>true</tt>, objects will be
795 * {@link PoolableObjectFactory#validateObject validated}
796 * before being returned to the pool within the
797 * {@link #returnObject}.
798 *
799 * @return <code>true</code> when objects will be validated after returned to {@link #returnObject}.
800 * @see #setTestOnReturn
801 */
802 public boolean getTestOnReturn() {
803 return _testOnReturn;
804 }
805
806 /**
807 * When <tt>true</tt>, objects will be
808 * {@link PoolableObjectFactory#validateObject validated}
809 * before being returned to the pool within the
810 * {@link #returnObject}.
811 *
812 * @param testOnReturn <code>true</code> so objects will be validated after returned to {@link #returnObject}.
813 * @see #getTestOnReturn
814 */
815 public void setTestOnReturn(boolean testOnReturn) {
816 _testOnReturn = testOnReturn;
817 }
818
819 /**
820 * Returns the number of milliseconds to sleep between runs of the
821 * idle object evictor thread.
822 * When non-positive, no idle object evictor thread will be
823 * run.
824 *
825 * @return number of milliseconds to sleep between evictor runs.
826 * @see #setTimeBetweenEvictionRunsMillis
827 */
828 public synchronized long getTimeBetweenEvictionRunsMillis() {
829 return _timeBetweenEvictionRunsMillis;
830 }
831
832 /**
833 * Sets the number of milliseconds to sleep between runs of the
834 * idle object evictor thread.
835 * When non-positive, no idle object evictor thread will be
836 * run.
837 *
838 * @param timeBetweenEvictionRunsMillis number of milliseconds to sleep between evictor runs.
839 * @see #getTimeBetweenEvictionRunsMillis
840 */
841 public synchronized void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) {
842 _timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
843 startEvictor(_timeBetweenEvictionRunsMillis);
844 }
845
846 /**
847 * Returns the max number of objects to examine during each run of the
848 * idle object evictor thread (if any).
849 *
850 * @return max number of objects to examine during each evictor run.
851 * @see #setNumTestsPerEvictionRun
852 * @see #setTimeBetweenEvictionRunsMillis
853 */
854 public synchronized int getNumTestsPerEvictionRun() {
855 return _numTestsPerEvictionRun;
856 }
857
858 /**
859 * Sets the max number of objects to examine during each run of the
860 * idle object evictor thread (if any).
861 * <p>
862 * When a negative value is supplied, <tt>ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})</tt>
863 * tests will be run. That is, when the value is <i>-n</i>, roughly one <i>n</i>th of the
864 * idle objects will be tested per run.
865 *
866 * @param numTestsPerEvictionRun max number of objects to examine during each evictor run.
867 * @see #getNumTestsPerEvictionRun
868 * @see #setTimeBetweenEvictionRunsMillis
869 */
870 public synchronized void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) {
871 _numTestsPerEvictionRun = numTestsPerEvictionRun;
872 }
873
874 /**
875 * Returns the minimum amount of time an object may sit idle in the pool
876 * before it is eligible for eviction by the idle object evictor
877 * (if any).
878 *
879 * @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
880 * @see #setMinEvictableIdleTimeMillis
881 * @see #setTimeBetweenEvictionRunsMillis
882 */
883 public synchronized long getMinEvictableIdleTimeMillis() {
884 return _minEvictableIdleTimeMillis;
885 }
886
887 /**
888 * Sets the minimum amount of time an object may sit idle in the pool
889 * before it is eligible for eviction by the idle object evictor
890 * (if any).
891 * When non-positive, no objects will be evicted from the pool
892 * due to idle time alone.
893 * @param minEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
894 * it is eligible for eviction.
895 * @see #getMinEvictableIdleTimeMillis
896 * @see #setTimeBetweenEvictionRunsMillis
897 */
898 public synchronized void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
899 _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
900 }
901
902 /**
903 * Returns the minimum amount of time an object may sit idle in the pool
904 * before it is eligible for eviction by the idle object evictor
905 * (if any), with the extra condition that at least
906 * "minIdle" amount of object remain in the pool.
907 *
908 * @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
909 * @since Pool 1.3
910 * @see #setSoftMinEvictableIdleTimeMillis
911 */
912 public synchronized long getSoftMinEvictableIdleTimeMillis() {
913 return _softMinEvictableIdleTimeMillis;
914 }
915
916 /**
917 * Sets the minimum amount of time an object may sit idle in the pool
918 * before it is eligible for eviction by the idle object evictor
919 * (if any), with the extra condition that at least
920 * "minIdle" object instances remain in the pool.
921 * When non-positive, no objects will be evicted from the pool
922 * due to idle time alone.
923 *
924 * @param softMinEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
925 * it is eligible for eviction.
926 * @since Pool 1.3
927 * @see #getSoftMinEvictableIdleTimeMillis
928 */
929 public synchronized void setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis) {
930 _softMinEvictableIdleTimeMillis = softMinEvictableIdleTimeMillis;
931 }
932
933 /**
934 * When <tt>true</tt>, objects will be
935 * {@link PoolableObjectFactory#validateObject validated}
936 * by the idle object evictor (if any). If an object
937 * fails to validate, it will be dropped from the pool.
938 *
939 * @return <code>true</code> when objects will be validated by the evictor.
940 * @see #setTestWhileIdle
941 * @see #setTimeBetweenEvictionRunsMillis
942 */
943 public synchronized boolean getTestWhileIdle() {
944 return _testWhileIdle;
945 }
946
947 /**
948 * When <tt>true</tt>, objects will be
949 * {@link PoolableObjectFactory#validateObject validated}
950 * by the idle object evictor (if any). If an object
951 * fails to validate, it will be dropped from the pool.
952 *
953 * @param testWhileIdle <code>true</code> so objects will be validated by the evictor.
954 * @see #getTestWhileIdle
955 * @see #setTimeBetweenEvictionRunsMillis
956 */
957 public synchronized void setTestWhileIdle(boolean testWhileIdle) {
958 _testWhileIdle = testWhileIdle;
959 }
960
961 /**
962 * Whether or not the idle object pool acts as a LIFO queue. True means
963 * that borrowObject returns the most recently used ("last in") idle object
964 * in the pool (if there are idle instances available). False means that
965 * the pool behaves as a FIFO queue - objects are taken from the idle object
966 * pool in the order that they are returned to the pool.
967 *
968 * @return <code>true</true> if the pool is configured to act as a LIFO queue
969 * @since 1.4
970 */
971 public synchronized boolean getLifo() {
972 return _lifo;
973 }
974
975 /**
976 * Sets the LIFO property of the pool. True means that borrowObject returns
977 * the most recently used ("last in") idle object in the pool (if there are
978 * idle instances available). False means that the pool behaves as a FIFO
979 * queue - objects are taken from the idle object pool in the order that
980 * they are returned to the pool.
981 *
982 * @param lifo the new value for the LIFO property
983 * @since 1.4
984 */
985 public synchronized void setLifo(boolean lifo) {
986 this._lifo = lifo;
987 }
988
989 /**
990 * Sets my configuration.
991 *
992 * @param conf configuration to use.
993 * @see GenericObjectPool.Config
994 */
995 public synchronized void setConfig(GenericObjectPool.Config conf) {
996 setMaxIdle(conf.maxIdle);
997 setMinIdle(conf.minIdle);
998 setMaxActive(conf.maxActive);
999 setMaxWait(conf.maxWait);
1000 setWhenExhaustedAction(conf.whenExhaustedAction);
1001 setTestOnBorrow(conf.testOnBorrow);
1002 setTestOnReturn(conf.testOnReturn);
1003 setTestWhileIdle(conf.testWhileIdle);
1004 setNumTestsPerEvictionRun(conf.numTestsPerEvictionRun);
1005 setMinEvictableIdleTimeMillis(conf.minEvictableIdleTimeMillis);
1006 setTimeBetweenEvictionRunsMillis(conf.timeBetweenEvictionRunsMillis);
1007 setSoftMinEvictableIdleTimeMillis(conf.softMinEvictableIdleTimeMillis);
1008 setLifo(conf.lifo);
1009 allocate();
1010 }
1011
1012 //-- ObjectPool methods ------------------------------------------
1013
1014 /**
1015 * <p>Borrows an object from the pool.</p>
1016 *
1017 * <p>If there is an idle instance available in the pool, then either the most-recently returned
1018 * (if {@link #getLifo() lifo} == true) or "oldest" (lifo == false) instance sitting idle in the pool
1019 * will be activated and returned. If activation fails, or {@link #getTestOnBorrow() testOnBorrow} is set
1020 * to true and validation fails, the instance is destroyed and the next available instance is examined.
1021 * This continues until either a valid instance is returned or there are no more idle instances available.</p>
1022 *
1023 * <p>If there are no idle instances available in the pool, behavior depends on the {@link #getMaxActive() maxActive}
1024 * and (if applicable) {@link #getWhenExhaustedAction() whenExhaustedAction} and {@link #getMaxWait() maxWait}
1025 * properties. If the number of instances checked out from the pool is less than <code>maxActive,</code> a new
1026 * instance is created, activated and (if applicable) validated and returned to the caller.</p>
1027 *
1028 * <p>If the pool is exhausted (no available idle instances and no capacity to create new ones),
1029 * this method will either block ({@link #WHEN_EXHAUSTED_BLOCK}), throw a <code>NoSuchElementException</code>
1030 * ({@link #WHEN_EXHAUSTED_FAIL}), or grow ({@link #WHEN_EXHAUSTED_GROW} - ignoring maxActive).
1031 * The length of time that this method will block when <code>whenExhaustedAction == WHEN_EXHAUSTED_BLOCK</code>
1032 * is determined by the {@link #getMaxWait() maxWait} property.</p>
1033 *
1034 * <p>When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances
1035 * to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive
1036 * available instances in request arrival order.</p>
1037 *
1038 * @return object instance
1039 * @throws NoSuchElementException if an instance cannot be returned
1040 */
1041 public Object borrowObject() throws Exception {
1042 long starttime = System.currentTimeMillis();
1043 Latch latch = new Latch();
1044 byte whenExhaustedAction;
1045 long maxWait;
1046 synchronized (this) {
1047 // Get local copy of current config. Can't sync when used later as
1048 // it can result in a deadlock. Has the added advantage that config
1049 // is consistent for entire method execution
1050 whenExhaustedAction = _whenExhaustedAction;
1051 maxWait = _maxWait;
1052
1053 // Add this request to the queue
1054 _allocationQueue.add(latch);
1055
1056 // Work the allocation queue, allocating idle instances and
1057 // instance creation permits in request arrival order
1058 allocate();
1059 }
1060
1061 for(;;) {
1062 synchronized (this) {
1063 assertOpen();
1064 }
1065
1066 // If no object was allocated from the pool above
1067 if(latch.getPair() == null) {
1068 // check if we were allowed to create one
1069 if(latch.mayCreate()) {
1070 // allow new object to be created
1071 } else {
1072 // the pool is exhausted
1073 switch(whenExhaustedAction) {
1074 case WHEN_EXHAUSTED_GROW:
1075 // allow new object to be created
1076 synchronized (this) {
1077 // Make sure allocate hasn't already assigned an object
1078 // in a different thread
1079 if (latch.getPair() == null) {
1080 _allocationQueue.remove(latch);
1081 _numInternalProcessing++;
1082 }
1083 }
1084 break;
1085 case WHEN_EXHAUSTED_FAIL:
1086 synchronized (this) {
1087 // Make sure allocate hasn't already assigned an object
1088 // in a different thread
1089 if (latch.getPair() != null) {
1090 break;
1091 }
1092 _allocationQueue.remove(latch);
1093 }
1094 throw new NoSuchElementException("Pool exhausted");
1095 case WHEN_EXHAUSTED_BLOCK:
1096 try {
1097 synchronized (latch) {
1098 if(maxWait <= 0) {
1099 latch.wait();
1100 } else {
1101 // this code may be executed again after a notify then continue cycle
1102 // so, need to calculate the amount of time to wait
1103 final long elapsed = (System.currentTimeMillis() - starttime);
1104 final long waitTime = maxWait - elapsed;
1105 if (waitTime > 0)
1106 {
1107 latch.wait(waitTime);
1108 }
1109 }
1110 }
1111 } catch(InterruptedException e) {
1112 Thread.currentThread().interrupt();
1113 throw e;
1114 }
1115 if(maxWait > 0 && ((System.currentTimeMillis() - starttime) >= maxWait)) {
1116 synchronized(this) {
1117 // Make sure allocate hasn't already assigned an object
1118 // in a different thread
1119 if (latch.getPair() == null) {
1120 // Remove latch from the allocation queue
1121 _allocationQueue.remove(latch);
1122 } else {
1123 break;
1124 }
1125 }
1126 throw new NoSuchElementException("Timeout waiting for idle object");
1127 } else {
1128 continue; // keep looping
1129 }
1130 default:
1131 throw new IllegalArgumentException("WhenExhaustedAction property " + whenExhaustedAction +
1132 " not recognized.");
1133 }
1134 }
1135 }
1136
1137 boolean newlyCreated = false;
1138 if(null == latch.getPair()) {
1139 try {
1140 Object obj = _factory.makeObject();
1141 latch.setPair(new ObjectTimestampPair(obj));
1142 newlyCreated = true;
1143 } finally {
1144 if (!newlyCreated) {
1145 // object cannot be created
1146 synchronized (this) {
1147 _numInternalProcessing--;
1148 // No need to reset latch - about to throw exception
1149 allocate();
1150 }
1151 }
1152 }
1153 }
1154 // activate & validate the object
1155 try {
1156 _factory.activateObject(latch.getPair().value);
1157 if(_testOnBorrow &&
1158 !_factory.validateObject(latch.getPair().value)) {
1159 throw new Exception("ValidateObject failed");
1160 }
1161 synchronized(this) {
1162 _numInternalProcessing--;
1163 _numActive++;
1164 }
1165 return latch.getPair().value;
1166 }
1167 catch (Throwable e) {
1168 // object cannot be activated or is invalid
1169 try {
1170 _factory.destroyObject(latch.getPair().value);
1171 } catch (Throwable e2) {
1172 // cannot destroy broken object
1173 }
1174 synchronized (this) {
1175 _numInternalProcessing--;
1176 latch.reset();
1177 _allocationQueue.add(0, latch);
1178 allocate();
1179 }
1180 if(newlyCreated) {
1181 throw new NoSuchElementException("Could not create a validated object, cause: " + e.getMessage());
1182 }
1183 else {
1184 continue; // keep looping
1185 }
1186 }
1187 }
1188 }
1189
1190 /**
1191 * Allocate available instances to latches in the allocation queue. Then
1192 * set _mayCreate to true for as many additional latches remaining in queue
1193 * as _maxActive allows.
1194 */
1195 private synchronized void allocate() {
1196 if (isClosed()) return;
1197
1198 // First use any objects in the pool to clear the queue
1199 for (;;) {
1200 if (!_pool.isEmpty() && !_allocationQueue.isEmpty()) {
1201 Latch latch = (Latch) _allocationQueue.removeFirst();
1202 latch.setPair((ObjectTimestampPair) _pool.removeFirst());
1203 _numInternalProcessing++;
1204 synchronized (latch) {
1205 latch.notify();
1206 }
1207 } else {
1208 break;
1209 }
1210 }
1211
1212 // Second utilise any spare capacity to create new objects
1213 for(;;) {
1214 if((!_allocationQueue.isEmpty()) && (_maxActive < 0 || (_numActive + _numInternalProcessing) < _maxActive)) {
1215 Latch latch = (Latch) _allocationQueue.removeFirst();
1216 latch.setMayCreate(true);
1217 _numInternalProcessing++;
1218 synchronized (latch) {
1219 latch.notify();
1220 }
1221 } else {
1222 break;
1223 }
1224 }
1225 }
1226
1227 /**
1228 * <p>Invalidates the given object instance. Decrements the active count
1229 * and destroys the instance.</p>
1230 *
1231 * @param obj instance to invalidate
1232 * @throws Exception if an exception occurs destroying the object
1233 */
1234 public void invalidateObject(Object obj) throws Exception {
1235 try {
1236 if (_factory != null) {
1237 _factory.destroyObject(obj);
1238 }
1239 } finally {
1240 synchronized (this) {
1241 _numActive--;
1242 allocate();
1243 }
1244 }
1245 }
1246
1247 /**
1248 * Clears any objects sitting idle in the pool.
1249 */
1250 public void clear() {
1251 List toDestroy = new ArrayList();
1252
1253 synchronized(this) {
1254 toDestroy.addAll(_pool);
1255 _numInternalProcessing = _numInternalProcessing + _pool._size;
1256 _pool.clear();
1257 }
1258 destroy(toDestroy);
1259 }
1260
1261 /**
1262 * Private method to destroy all the objects in a collection. Assumes
1263 * objects in the collection are instances of ObjectTimestampPair
1264 *
1265 * @param c Collection of objects to destroy
1266 */
1267 private void destroy(Collection c) {
1268 for (Iterator it = c.iterator(); it.hasNext();) {
1269 try {
1270 _factory.destroyObject(((ObjectTimestampPair)(it.next())).value);
1271 } catch(Exception e) {
1272 // ignore error, keep destroying the rest
1273 } finally {
1274 synchronized(this) {
1275 _numInternalProcessing--;
1276 allocate();
1277 }
1278 }
1279 }
1280 }
1281
1282 /**
1283 * Return the number of instances currently borrowed from this pool.
1284 *
1285 * @return the number of instances currently borrowed from this pool
1286 */
1287 public synchronized int getNumActive() {
1288 return _numActive;
1289 }
1290
1291 /**
1292 * Return the number of instances currently idle in this pool.
1293 *
1294 * @return the number of instances currently idle in this pool
1295 */
1296 public synchronized int getNumIdle() {
1297 return _pool.size();
1298 }
1299
1300 /**
1301 * <p>Returns an object instance to the pool.</p>
1302 *
1303 * <p>If {@link #getMaxIdle() maxIdle} is set to a positive value and the number of idle instances
1304 * has reached this value, the returning instance is destroyed.</p>
1305 *
1306 * <p>If {@link #getTestOnReturn() testOnReturn} == true, the returning instance is validated before being returned
1307 * to the idle instance pool. In this case, if validation fails, the instance is destroyed.</p>
1308 *
1309 * <p><strong>Note: </strong> There is no guard to prevent an object
1310 * being returned to the pool multiple times. Clients are expected to
1311 * discard references to returned objects and ensure that an object is not
1312 * returned to the pool multiple times in sequence (i.e., without being
1313 * borrowed again between returns). Violating this contract will result in
1314 * the same object appearing multiple times in the pool and pool counters
1315 * (numActive, numIdle) returning incorrect values.</p>
1316 *
1317 * @param obj instance to return to the pool
1318 */
1319 public void returnObject(Object obj) throws Exception {
1320 try {
1321 addObjectToPool(obj, true);
1322 } catch (Exception e) {
1323 if (_factory != null) {
1324 try {
1325 _factory.destroyObject(obj);
1326 } catch (Exception e2) {
1327 // swallowed
1328 }
1329 // TODO: Correctness here depends on control in addObjectToPool.
1330 // These two methods should be refactored, removing the
1331 // "behavior flag", decrementNumActive, from addObjectToPool.
1332 synchronized(this) {
1333 _numActive--;
1334 allocate();
1335 }
1336 }
1337 }
1338 }
1339
1340 /**
1341 * <p>Adds an object to the pool.</p>
1342 *
1343 * <p>Validates the object if testOnReturn == true and passivates it before returning it to the pool.
1344 * if validation or passivation fails, or maxIdle is set and there is no room in the pool, the instance
1345 * is destroyed.</p>
1346 *
1347 * <p>Calls {@link #allocate()} on successful completion</p>
1348 *
1349 * @param obj instance to add to the pool
1350 * @param decrementNumActive whether or not to decrement the active count
1351 * @throws Exception
1352 */
1353 private void addObjectToPool(Object obj, boolean decrementNumActive) throws Exception {
1354 boolean success = true;
1355 if(_testOnReturn && !(_factory.validateObject(obj))) {
1356 success = false;
1357 } else {
1358 _factory.passivateObject(obj);
1359 }
1360
1361 boolean shouldDestroy = !success;
1362
1363 // Add instance to pool if there is room and it has passed validation
1364 // (if testOnreturn is set)
1365 synchronized (this) {
1366 if (isClosed()) {
1367 shouldDestroy = true;
1368 } else {
1369 if((_maxIdle >= 0) && (_pool.size() >= _maxIdle)) {
1370 shouldDestroy = true;
1371 } else if(success) {
1372 // borrowObject always takes the first element from the queue,
1373 // so for LIFO, push on top, FIFO add to end
1374 if (_lifo) {
1375 _pool.addFirst(new ObjectTimestampPair(obj));
1376 } else {
1377 _pool.addLast(new ObjectTimestampPair(obj));
1378 }
1379 if (decrementNumActive) {
1380 _numActive--;
1381 }
1382 allocate();
1383 }
1384 }
1385 }
1386
1387 // Destroy the instance if necessary
1388 if(shouldDestroy) {
1389 try {
1390 _factory.destroyObject(obj);
1391 } catch(Exception e) {
1392 // ignored
1393 }
1394 // Decrement active count *after* destroy if applicable
1395 if (decrementNumActive) {
1396 synchronized(this) {
1397 _numActive--;
1398 allocate();
1399 }
1400 }
1401 }
1402
1403 }
1404
1405 /**
1406 * Closes the pool. Once the pool is closed, {@link #borrowObject()}
1407 * will fail with IllegalStateException, but {@link #returnObject(Object)} and
1408 * {@link #invalidateObject(Object)} will continue to work. This method does not
1409 * {@link #clear()} the pool. The method is idempotent - that is, it is OK to call it on a closed
1410 * pool.
1411 *
1412 * @throws Exception
1413 */
1414 public void close() throws Exception {
1415 super.close();
1416 synchronized (this) {
1417 clear();
1418 startEvictor(-1L);
1419 }
1420 }
1421
1422 /**
1423 * Sets the {@link PoolableObjectFactory factory} this pool uses
1424 * to create new instances. Trying to change
1425 * the <code>factory</code> while there are borrowed objects will
1426 * throw an {@link IllegalStateException}.
1427 *
1428 * @param factory the {@link PoolableObjectFactory} used to create new instances.
1429 * @throws IllegalStateException when the factory cannot be set at this time
1430 */
1431 public void setFactory(PoolableObjectFactory factory) throws IllegalStateException {
1432 List toDestroy = new ArrayList();
1433 synchronized (this) {
1434 assertOpen();
1435 if(0 < getNumActive()) {
1436 throw new IllegalStateException("Objects are already active");
1437 } else {
1438 toDestroy.addAll(_pool);
1439 _numInternalProcessing = _numInternalProcessing + _pool._size;
1440 _pool.clear();
1441 }
1442 _factory = factory;
1443 }
1444 destroy(toDestroy);
1445 }
1446
1447 /**
1448 * <p>Perform <code>numTests</code> idle object eviction tests, evicting
1449 * examined objects that meet the criteria for eviction. If
1450 * <code>testWhileIdle</code> is true, examined objects are validated
1451 * when visited (and removed if invalid); otherwise only objects that
1452 * have been idle for more than <code>minEvicableIdletimeMillis</code>
1453 * are removed.</p>
1454 *
1455 * <p>Successive activations of this method examine objects in
1456 * in sequence, cycling through objects in oldest-to-youngest order.</p>
1457 *
1458 * @throws Exception if the pool is closed or eviction fails.
1459 */
1460 public void evict() throws Exception {
1461 assertOpen();
1462 synchronized (this) {
1463 if(_pool.isEmpty()) {
1464 return;
1465 }
1466 if (null == _evictionCursor) {
1467 _evictionCursor = (_pool.cursor(_lifo ? _pool.size() : 0));
1468 }
1469 }
1470
1471 for (int i=0,m=getNumTests();i<m;i++) {
1472 final ObjectTimestampPair pair;
1473 synchronized (this) {
1474 if ((_lifo && !_evictionCursor.hasPrevious()) ||
1475 !_lifo && !_evictionCursor.hasNext()) {
1476 _evictionCursor.close();
1477 _evictionCursor = _pool.cursor(_lifo ? _pool.size() : 0);
1478 }
1479
1480 pair = _lifo ?
1481 (ObjectTimestampPair) _evictionCursor.previous() :
1482 (ObjectTimestampPair) _evictionCursor.next();
1483
1484 _evictionCursor.remove();
1485 _numInternalProcessing++;
1486 }
1487
1488 boolean removeObject = false;
1489 final long idleTimeMilis = System.currentTimeMillis() - pair.tstamp;
1490 if ((getMinEvictableIdleTimeMillis() > 0) &&
1491 (idleTimeMilis > getMinEvictableIdleTimeMillis())) {
1492 removeObject = true;
1493 } else if ((getSoftMinEvictableIdleTimeMillis() > 0) &&
1494 (idleTimeMilis > getSoftMinEvictableIdleTimeMillis()) &&
1495 ((getNumIdle() + 1)> getMinIdle())) { // +1 accounts for object we are processing
1496 removeObject = true;
1497 }
1498 if(getTestWhileIdle() && !removeObject) {
1499 boolean active = false;
1500 try {
1501 _factory.activateObject(pair.value);
1502 active = true;
1503 } catch(Exception e) {
1504 removeObject=true;
1505 }
1506 if(active) {
1507 if(!_factory.validateObject(pair.value)) {
1508 removeObject=true;
1509 } else {
1510 try {
1511 _factory.passivateObject(pair.value);
1512 } catch(Exception e) {
1513 removeObject=true;
1514 }
1515 }
1516 }
1517 }
1518
1519 if (removeObject) {
1520 try {
1521 _factory.destroyObject(pair.value);
1522 } catch(Exception e) {
1523 // ignored
1524 }
1525 }
1526 synchronized (this) {
1527 if(!removeObject) {
1528 _evictionCursor.add(pair);
1529 if (_lifo) {
1530 // Skip over the element we just added back
1531 _evictionCursor.previous();
1532 }
1533 }
1534 _numInternalProcessing--;
1535 }
1536 }
1537 }
1538
1539 /**
1540 * Check to see if we are below our minimum number of objects
1541 * if so enough to bring us back to our minimum.
1542 *
1543 * @throws Exception when {@link #addObject()} fails.
1544 */
1545 private void ensureMinIdle() throws Exception {
1546 // this method isn't synchronized so the
1547 // calculateDeficit is done at the beginning
1548 // as a loop limit and a second time inside the loop
1549 // to stop when another thread already returned the
1550 // needed objects
1551 int objectDeficit = calculateDeficit(false);
1552 for ( int j = 0 ; j < objectDeficit && calculateDeficit(true) > 0 ; j++ ) {
1553 try {
1554 addObject();
1555 } finally {
1556 synchronized (this) {
1557 _numInternalProcessing--;
1558 allocate();
1559 }
1560 }
1561 }
1562 }
1563
1564 /**
1565 * This returns the number of objects to create during the pool
1566 * sustain cycle. This will ensure that the minimum number of idle
1567 * instances is maintained without going past the maxActive value.
1568 *
1569 * @param incrementInternal - Should the count of objects currently under
1570 * some form of internal processing be
1571 * incremented?
1572 * @return The number of objects to be created
1573 */
1574 private synchronized int calculateDeficit(boolean incrementInternal) {
1575 int objectDeficit = getMinIdle() - getNumIdle();
1576 if (_maxActive > 0) {
1577 int growLimit = Math.max(0,
1578 getMaxActive() - getNumActive() - getNumIdle() - _numInternalProcessing);
1579 objectDeficit = Math.min(objectDeficit, growLimit);
1580 }
1581 if (incrementInternal && objectDeficit >0) {
1582 _numInternalProcessing++;
1583 }
1584 return objectDeficit;
1585 }
1586
1587 /**
1588 * Create an object, and place it into the pool.
1589 * addObject() is useful for "pre-loading" a pool with idle objects.
1590 */
1591 public void addObject() throws Exception {
1592 assertOpen();
1593 if (_factory == null) {
1594 throw new IllegalStateException("Cannot add objects without a factory.");
1595 }
1596 Object obj = _factory.makeObject();
1597 try {
1598 assertOpen();
1599 addObjectToPool(obj, false);
1600 } catch (IllegalStateException ex) { // Pool closed
1601 try {
1602 _factory.destroyObject(obj);
1603 } catch (Exception ex2) {
1604 // swallow
1605 }
1606 throw ex;
1607 }
1608 }
1609
1610 //--- non-public methods ----------------------------------------
1611
1612 /**
1613 * Start the eviction thread or service, or when
1614 * <i>delay</i> is non-positive, stop it
1615 * if it is already running.
1616 *
1617 * @param delay milliseconds between evictor runs.
1618 */
1619 protected synchronized void startEvictor(long delay) {
1620 if(null != _evictor) {
1621 EvictionTimer.cancel(_evictor);
1622 _evictor = null;
1623 }
1624 if(delay > 0) {
1625 _evictor = new Evictor();
1626 EvictionTimer.schedule(_evictor, delay, delay);
1627 }
1628 }
1629
1630 synchronized String debugInfo() {
1631 StringBuffer buf = new StringBuffer();
1632 buf.append("Active: ").append(getNumActive()).append("\n");
1633 buf.append("Idle: ").append(getNumIdle()).append("\n");
1634 buf.append("Idle Objects:\n");
1635 Iterator it = _pool.iterator();
1636 long time = System.currentTimeMillis();
1637 while(it.hasNext()) {
1638 ObjectTimestampPair pair = (ObjectTimestampPair)(it.next());
1639 buf.append("\t").append(pair.value).append("\t").append(time - pair.tstamp).append("\n");
1640 }
1641 return buf.toString();
1642 }
1643
1644 private int getNumTests() {
1645 if(_numTestsPerEvictionRun >= 0) {
1646 return Math.min(_numTestsPerEvictionRun, _pool.size());
1647 } else {
1648 return(int)(Math.ceil(_pool.size()/Math.abs((double)_numTestsPerEvictionRun)));
1649 }
1650 }
1651
1652 //--- inner classes ----------------------------------------------
1653
1654 /**
1655 * The idle object evictor {@link TimerTask}.
1656 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1657 */
1658 private class Evictor extends TimerTask {
1659 public void run() {
1660 try {
1661 evict();
1662 } catch(Exception e) {
1663 // ignored
1664 } catch(OutOfMemoryError oome) {
1665 // Log problem but give evictor thread a chance to continue in
1666 // case error is recoverable
1667 oome.printStackTrace(System.err);
1668 }
1669 try {
1670 ensureMinIdle();
1671 } catch(Exception e) {
1672 // ignored
1673 }
1674 }
1675 }
1676
1677 /**
1678 * A simple "struct" encapsulating the
1679 * configuration information for a {@link GenericObjectPool}.
1680 * @see GenericObjectPool#GenericObjectPool(org.apache.commons.pool.PoolableObjectFactory,
1681 * org.apache.commons.pool.impl.GenericObjectPool.Config)
1682 * @see GenericObjectPool#setConfig
1683 */
1684 public static class Config {
1685 /**
1686 * @see GenericObjectPool#setMaxIdle
1687 */
1688 public int maxIdle = GenericObjectPool.DEFAULT_MAX_IDLE;
1689 /**
1690 * @see GenericObjectPool#setMinIdle
1691 */
1692 public int minIdle = GenericObjectPool.DEFAULT_MIN_IDLE;
1693 /**
1694 * @see GenericObjectPool#setMaxActive
1695 */
1696 public int maxActive = GenericObjectPool.DEFAULT_MAX_ACTIVE;
1697 /**
1698 * @see GenericObjectPool#setMaxWait
1699 */
1700 public long maxWait = GenericObjectPool.DEFAULT_MAX_WAIT;
1701 /**
1702 * @see GenericObjectPool#setWhenExhaustedAction
1703 */
1704 public byte whenExhaustedAction = GenericObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
1705 /**
1706 * @see GenericObjectPool#setTestOnBorrow
1707 */
1708 public boolean testOnBorrow = GenericObjectPool.DEFAULT_TEST_ON_BORROW;
1709 /**
1710 * @see GenericObjectPool#setTestOnReturn
1711 */
1712 public boolean testOnReturn = GenericObjectPool.DEFAULT_TEST_ON_RETURN;
1713 /**
1714 * @see GenericObjectPool#setTestWhileIdle
1715 */
1716 public boolean testWhileIdle = GenericObjectPool.DEFAULT_TEST_WHILE_IDLE;
1717 /**
1718 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1719 */
1720 public long timeBetweenEvictionRunsMillis = GenericObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1721 /**
1722 * @see GenericObjectPool#setNumTestsPerEvictionRun
1723 */
1724 public int numTestsPerEvictionRun = GenericObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1725 /**
1726 * @see GenericObjectPool#setMinEvictableIdleTimeMillis
1727 */
1728 public long minEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1729 /**
1730 * @see GenericObjectPool#setSoftMinEvictableIdleTimeMillis
1731 */
1732 public long softMinEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1733 /**
1734 * @see GenericObjectPool#setLifo
1735 */
1736 public boolean lifo = GenericObjectPool.DEFAULT_LIFO;
1737
1738 }
1739
1740 /**
1741 * Latch used to control allocation order of objects to threads to ensure
1742 * fairness. That is, objects are allocated to threads in the order that
1743 * threads request objects.
1744 */
1745 private static final class Latch {
1746
1747 /** object timestamp pair allocated to this latch */
1748 private ObjectTimestampPair _pair;
1749
1750 /** Wheter or not this latch may create an object instance */
1751 private boolean _mayCreate = false;
1752
1753 /**
1754 * Returns ObjectTimestampPair allocated to this latch
1755 * @return ObjectTimestampPair allocated to this latch
1756 */
1757 private synchronized ObjectTimestampPair getPair() {
1758 return _pair;
1759 }
1760
1761 /**
1762 * Sets ObjectTimestampPair on this latch
1763 * @param pair ObjectTimestampPair allocated to this latch
1764 */
1765 private synchronized void setPair(ObjectTimestampPair pair) {
1766 _pair = pair;
1767 }
1768
1769 /**
1770 * Whether or not this latch may create an object instance
1771 * @return true if this latch has an instance creation permit
1772 */
1773 private synchronized boolean mayCreate() {
1774 return _mayCreate;
1775 }
1776
1777 /**
1778 * Sets the mayCreate property
1779 * @param mayCreate new value for mayCreate
1780 */
1781 private synchronized void setMayCreate(boolean mayCreate) {
1782 _mayCreate = mayCreate;
1783 }
1784
1785 /**
1786 * Reset the latch data. Used when an allocation fails and the latch
1787 * needs to be re-added to the queue.
1788 */
1789 private synchronized void reset() {
1790 _pair = null;
1791 _mayCreate = false;
1792 }
1793 }
1794
1795
1796 //--- private attributes ---------------------------------------
1797
1798 /**
1799 * The cap on the number of idle instances in the pool.
1800 * @see #setMaxIdle
1801 * @see #getMaxIdle
1802 */
1803 private int _maxIdle = DEFAULT_MAX_IDLE;
1804
1805 /**
1806 * The cap on the minimum number of idle instances in the pool.
1807 * @see #setMinIdle
1808 * @see #getMinIdle
1809 */
1810 private int _minIdle = DEFAULT_MIN_IDLE;
1811
1812 /**
1813 * The cap on the total number of active instances from the pool.
1814 * @see #setMaxActive
1815 * @see #getMaxActive
1816 */
1817 private int _maxActive = DEFAULT_MAX_ACTIVE;
1818
1819 /**
1820 * The maximum amount of time (in millis) the
1821 * {@link #borrowObject} method should block before throwing
1822 * an exception when the pool is exhausted and the
1823 * {@link #getWhenExhaustedAction "when exhausted" action} is
1824 * {@link #WHEN_EXHAUSTED_BLOCK}.
1825 *
1826 * When less than or equal to 0, the {@link #borrowObject} method
1827 * may block indefinitely.
1828 *
1829 * @see #setMaxWait
1830 * @see #getMaxWait
1831 * @see #WHEN_EXHAUSTED_BLOCK
1832 * @see #setWhenExhaustedAction
1833 * @see #getWhenExhaustedAction
1834 */
1835 private long _maxWait = DEFAULT_MAX_WAIT;
1836
1837 /**
1838 * The action to take when the {@link #borrowObject} method
1839 * is invoked when the pool is exhausted (the maximum number
1840 * of "active" objects has been reached).
1841 *
1842 * @see #WHEN_EXHAUSTED_BLOCK
1843 * @see #WHEN_EXHAUSTED_FAIL
1844 * @see #WHEN_EXHAUSTED_GROW
1845 * @see #DEFAULT_WHEN_EXHAUSTED_ACTION
1846 * @see #setWhenExhaustedAction
1847 * @see #getWhenExhaustedAction
1848 */
1849 private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
1850
1851 /**
1852 * When <tt>true</tt>, objects will be
1853 * {@link PoolableObjectFactory#validateObject validated}
1854 * before being returned by the {@link #borrowObject}
1855 * method. If the object fails to validate,
1856 * it will be dropped from the pool, and we will attempt
1857 * to borrow another.
1858 *
1859 * @see #setTestOnBorrow
1860 * @see #getTestOnBorrow
1861 */
1862 private volatile boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
1863
1864 /**
1865 * When <tt>true</tt>, objects will be
1866 * {@link PoolableObjectFactory#validateObject validated}
1867 * before being returned to the pool within the
1868 * {@link #returnObject}.
1869 *
1870 * @see #getTestOnReturn
1871 * @see #setTestOnReturn
1872 */
1873 private volatile boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
1874
1875 /**
1876 * When <tt>true</tt>, objects will be
1877 * {@link PoolableObjectFactory#validateObject validated}
1878 * by the idle object evictor (if any). If an object
1879 * fails to validate, it will be dropped from the pool.
1880 *
1881 * @see #setTestWhileIdle
1882 * @see #getTestWhileIdle
1883 * @see #getTimeBetweenEvictionRunsMillis
1884 * @see #setTimeBetweenEvictionRunsMillis
1885 */
1886 private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
1887
1888 /**
1889 * The number of milliseconds to sleep between runs of the
1890 * idle object evictor thread.
1891 * When non-positive, no idle object evictor thread will be
1892 * run.
1893 *
1894 * @see #setTimeBetweenEvictionRunsMillis
1895 * @see #getTimeBetweenEvictionRunsMillis
1896 */
1897 private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1898
1899 /**
1900 * The max number of objects to examine during each run of the
1901 * idle object evictor thread (if any).
1902 * <p>
1903 * When a negative value is supplied, <tt>ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})</tt>
1904 * tests will be run. I.e., when the value is <i>-n</i>, roughly one <i>n</i>th of the
1905 * idle objects will be tested per run.
1906 *
1907 * @see #setNumTestsPerEvictionRun
1908 * @see #getNumTestsPerEvictionRun
1909 * @see #getTimeBetweenEvictionRunsMillis
1910 * @see #setTimeBetweenEvictionRunsMillis
1911 */
1912 private int _numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1913
1914 /**
1915 * The minimum amount of time an object may sit idle in the pool
1916 * before it is eligible for eviction by the idle object evictor
1917 * (if any).
1918 * When non-positive, no objects will be evicted from the pool
1919 * due to idle time alone.
1920 *
1921 * @see #setMinEvictableIdleTimeMillis
1922 * @see #getMinEvictableIdleTimeMillis
1923 * @see #getTimeBetweenEvictionRunsMillis
1924 * @see #setTimeBetweenEvictionRunsMillis
1925 */
1926 private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1927
1928 /**
1929 * The minimum amount of time an object may sit idle in the pool
1930 * before it is eligible for eviction by the idle object evictor
1931 * (if any), with the extra condition that at least
1932 * "minIdle" amount of object remain in the pool.
1933 * When non-positive, no objects will be evicted from the pool
1934 * due to idle time alone.
1935 *
1936 * @see #setSoftMinEvictableIdleTimeMillis
1937 * @see #getSoftMinEvictableIdleTimeMillis
1938 */
1939 private long _softMinEvictableIdleTimeMillis = DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1940
1941 /** Whether or not the pool behaves as a LIFO queue (last in first out) */
1942 private boolean _lifo = DEFAULT_LIFO;
1943
1944 /** My pool. */
1945 private CursorableLinkedList _pool = null;
1946
1947 /** Eviction cursor - keeps track of idle object evictor position */
1948 private CursorableLinkedList.Cursor _evictionCursor = null;
1949
1950 /** My {@link PoolableObjectFactory}. */
1951 private PoolableObjectFactory _factory = null;
1952
1953 /**
1954 * The number of objects {@link #borrowObject} borrowed
1955 * from the pool, but not yet returned.
1956 */
1957 private int _numActive = 0;
1958
1959 /**
1960 * My idle object eviction {@link TimerTask}, if any.
1961 */
1962 private Evictor _evictor = null;
1963
1964 /**
1965 * The number of objects subject to some form of internal processing
1966 * (usually creation or destruction) that should be included in the total
1967 * number of objects but are neither active nor idle.
1968 */
1969 private int _numInternalProcessing = 0;
1970
1971 /**
1972 * Used to track the order in which threads call {@link #borrowObject()} so
1973 * that objects can be allocated in the order in which the threads requested
1974 * them.
1975 */
1976 private LinkedList _allocationQueue = new LinkedList();
1977
1978 }