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: 812938 $ $Date: 2009-09-09 09:09:26 -0400 (Wed, 09 Sep 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. When the value is positive, the number of tests
865 * actually performed in each run will be the minimum of this value and the number of instances
866 * idle in the pool.
867 *
868 * @param numTestsPerEvictionRun max number of objects to examine during each evictor run.
869 * @see #getNumTestsPerEvictionRun
870 * @see #setTimeBetweenEvictionRunsMillis
871 */
872 public synchronized void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) {
873 _numTestsPerEvictionRun = numTestsPerEvictionRun;
874 }
875
876 /**
877 * Returns the minimum amount of time an object may sit idle in the pool
878 * before it is eligible for eviction by the idle object evictor
879 * (if any).
880 *
881 * @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
882 * @see #setMinEvictableIdleTimeMillis
883 * @see #setTimeBetweenEvictionRunsMillis
884 */
885 public synchronized long getMinEvictableIdleTimeMillis() {
886 return _minEvictableIdleTimeMillis;
887 }
888
889 /**
890 * Sets the minimum amount of time an object may sit idle in the pool
891 * before it is eligible for eviction by the idle object evictor
892 * (if any).
893 * When non-positive, no objects will be evicted from the pool
894 * due to idle time alone.
895 * @param minEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
896 * it is eligible for eviction.
897 * @see #getMinEvictableIdleTimeMillis
898 * @see #setTimeBetweenEvictionRunsMillis
899 */
900 public synchronized void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
901 _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
902 }
903
904 /**
905 * Returns the minimum amount of time an object may sit idle in the pool
906 * before it is eligible for eviction by the idle object evictor
907 * (if any), with the extra condition that at least
908 * "minIdle" amount of object remain in the pool.
909 *
910 * @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
911 * @since Pool 1.3
912 * @see #setSoftMinEvictableIdleTimeMillis
913 */
914 public synchronized long getSoftMinEvictableIdleTimeMillis() {
915 return _softMinEvictableIdleTimeMillis;
916 }
917
918 /**
919 * Sets the minimum amount of time an object may sit idle in the pool
920 * before it is eligible for eviction by the idle object evictor
921 * (if any), with the extra condition that at least
922 * "minIdle" object instances remain in the pool.
923 * When non-positive, no objects will be evicted from the pool
924 * due to idle time alone.
925 *
926 * @param softMinEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
927 * it is eligible for eviction.
928 * @since Pool 1.3
929 * @see #getSoftMinEvictableIdleTimeMillis
930 */
931 public synchronized void setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis) {
932 _softMinEvictableIdleTimeMillis = softMinEvictableIdleTimeMillis;
933 }
934
935 /**
936 * When <tt>true</tt>, objects will be
937 * {@link PoolableObjectFactory#validateObject validated}
938 * by the idle object evictor (if any). If an object
939 * fails to validate, it will be dropped from the pool.
940 *
941 * @return <code>true</code> when objects will be validated by the evictor.
942 * @see #setTestWhileIdle
943 * @see #setTimeBetweenEvictionRunsMillis
944 */
945 public synchronized boolean getTestWhileIdle() {
946 return _testWhileIdle;
947 }
948
949 /**
950 * When <tt>true</tt>, objects will be
951 * {@link PoolableObjectFactory#validateObject validated}
952 * by the idle object evictor (if any). If an object
953 * fails to validate, it will be dropped from the pool.
954 *
955 * @param testWhileIdle <code>true</code> so objects will be validated by the evictor.
956 * @see #getTestWhileIdle
957 * @see #setTimeBetweenEvictionRunsMillis
958 */
959 public synchronized void setTestWhileIdle(boolean testWhileIdle) {
960 _testWhileIdle = testWhileIdle;
961 }
962
963 /**
964 * Whether or not the idle object pool acts as a LIFO queue. True means
965 * that borrowObject returns the most recently used ("last in") idle object
966 * in the pool (if there are idle instances available). False means that
967 * the pool behaves as a FIFO queue - objects are taken from the idle object
968 * pool in the order that they are returned to the pool.
969 *
970 * @return <code>true</true> if the pool is configured to act as a LIFO queue
971 * @since 1.4
972 */
973 public synchronized boolean getLifo() {
974 return _lifo;
975 }
976
977 /**
978 * Sets the LIFO property of the pool. True means that borrowObject returns
979 * the most recently used ("last in") idle object in the pool (if there are
980 * idle instances available). False means that the pool behaves as a FIFO
981 * queue - objects are taken from the idle object pool in the order that
982 * they are returned to the pool.
983 *
984 * @param lifo the new value for the LIFO property
985 * @since 1.4
986 */
987 public synchronized void setLifo(boolean lifo) {
988 this._lifo = lifo;
989 }
990
991 /**
992 * Sets my configuration.
993 *
994 * @param conf configuration to use.
995 * @see GenericObjectPool.Config
996 */
997 public synchronized void setConfig(GenericObjectPool.Config conf) {
998 setMaxIdle(conf.maxIdle);
999 setMinIdle(conf.minIdle);
1000 setMaxActive(conf.maxActive);
1001 setMaxWait(conf.maxWait);
1002 setWhenExhaustedAction(conf.whenExhaustedAction);
1003 setTestOnBorrow(conf.testOnBorrow);
1004 setTestOnReturn(conf.testOnReturn);
1005 setTestWhileIdle(conf.testWhileIdle);
1006 setNumTestsPerEvictionRun(conf.numTestsPerEvictionRun);
1007 setMinEvictableIdleTimeMillis(conf.minEvictableIdleTimeMillis);
1008 setTimeBetweenEvictionRunsMillis(conf.timeBetweenEvictionRunsMillis);
1009 setSoftMinEvictableIdleTimeMillis(conf.softMinEvictableIdleTimeMillis);
1010 setLifo(conf.lifo);
1011 allocate();
1012 }
1013
1014 //-- ObjectPool methods ------------------------------------------
1015
1016 /**
1017 * <p>Borrows an object from the pool.</p>
1018 *
1019 * <p>If there is an idle instance available in the pool, then either the most-recently returned
1020 * (if {@link #getLifo() lifo} == true) or "oldest" (lifo == false) instance sitting idle in the pool
1021 * will be activated and returned. If activation fails, or {@link #getTestOnBorrow() testOnBorrow} is set
1022 * to true and validation fails, the instance is destroyed and the next available instance is examined.
1023 * This continues until either a valid instance is returned or there are no more idle instances available.</p>
1024 *
1025 * <p>If there are no idle instances available in the pool, behavior depends on the {@link #getMaxActive() maxActive}
1026 * and (if applicable) {@link #getWhenExhaustedAction() whenExhaustedAction} and {@link #getMaxWait() maxWait}
1027 * properties. If the number of instances checked out from the pool is less than <code>maxActive,</code> a new
1028 * instance is created, activated and (if applicable) validated and returned to the caller.</p>
1029 *
1030 * <p>If the pool is exhausted (no available idle instances and no capacity to create new ones),
1031 * this method will either block ({@link #WHEN_EXHAUSTED_BLOCK}), throw a <code>NoSuchElementException</code>
1032 * ({@link #WHEN_EXHAUSTED_FAIL}), or grow ({@link #WHEN_EXHAUSTED_GROW} - ignoring maxActive).
1033 * The length of time that this method will block when <code>whenExhaustedAction == WHEN_EXHAUSTED_BLOCK</code>
1034 * is determined by the {@link #getMaxWait() maxWait} property.</p>
1035 *
1036 * <p>When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances
1037 * to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive
1038 * available instances in request arrival order.</p>
1039 *
1040 * @return object instance
1041 * @throws NoSuchElementException if an instance cannot be returned
1042 */
1043 public Object borrowObject() throws Exception {
1044 long starttime = System.currentTimeMillis();
1045 Latch latch = new Latch();
1046 byte whenExhaustedAction;
1047 long maxWait;
1048 synchronized (this) {
1049 // Get local copy of current config. Can't sync when used later as
1050 // it can result in a deadlock. Has the added advantage that config
1051 // is consistent for entire method execution
1052 whenExhaustedAction = _whenExhaustedAction;
1053 maxWait = _maxWait;
1054
1055 // Add this request to the queue
1056 _allocationQueue.add(latch);
1057
1058 // Work the allocation queue, allocating idle instances and
1059 // instance creation permits in request arrival order
1060 allocate();
1061 }
1062
1063 for(;;) {
1064 synchronized (this) {
1065 assertOpen();
1066 }
1067
1068 // If no object was allocated from the pool above
1069 if(latch.getPair() == null) {
1070 // check if we were allowed to create one
1071 if(latch.mayCreate()) {
1072 // allow new object to be created
1073 } else {
1074 // the pool is exhausted
1075 switch(whenExhaustedAction) {
1076 case WHEN_EXHAUSTED_GROW:
1077 // allow new object to be created
1078 synchronized (this) {
1079 // Make sure another thread didn't allocate us an object
1080 // or permit a new object to be created
1081 if (latch.getPair() == null && !latch.mayCreate()) {
1082 _allocationQueue.remove(latch);
1083 _numInternalProcessing++;
1084 }
1085 }
1086 break;
1087 case WHEN_EXHAUSTED_FAIL:
1088 synchronized (this) {
1089 // Make sure allocate hasn't already assigned an object
1090 // in a different thread or permitted a new object to be created
1091 if (latch.getPair() != null || latch.mayCreate()) {
1092 break;
1093 }
1094 _allocationQueue.remove(latch);
1095 }
1096 throw new NoSuchElementException("Pool exhausted");
1097 case WHEN_EXHAUSTED_BLOCK:
1098 try {
1099 synchronized (latch) {
1100 // Before we wait, make sure another thread didn't allocate us an object
1101 // or permit a new object to be created
1102 if (latch.getPair() == null && !latch.mayCreate()) {
1103 if(maxWait <= 0) {
1104 latch.wait();
1105 } else {
1106 // this code may be executed again after a notify then continue cycle
1107 // so, need to calculate the amount of time to wait
1108 final long elapsed = (System.currentTimeMillis() - starttime);
1109 final long waitTime = maxWait - elapsed;
1110 if (waitTime > 0)
1111 {
1112 latch.wait(waitTime);
1113 }
1114 }
1115 } else {
1116 break;
1117 }
1118 }
1119 } catch(InterruptedException e) {
1120 Thread.currentThread().interrupt();
1121 throw e;
1122 }
1123 if(maxWait > 0 && ((System.currentTimeMillis() - starttime) >= maxWait)) {
1124 synchronized(this) {
1125 // Make sure allocate hasn't already assigned an object
1126 // in a different thread or permitted a new object to be created
1127 if (latch.getPair() == null && !latch.mayCreate()) {
1128 // Remove latch from the allocation queue
1129 _allocationQueue.remove(latch);
1130 } else {
1131 break;
1132 }
1133 }
1134 throw new NoSuchElementException("Timeout waiting for idle object");
1135 } else {
1136 continue; // keep looping
1137 }
1138 default:
1139 throw new IllegalArgumentException("WhenExhaustedAction property " + whenExhaustedAction +
1140 " not recognized.");
1141 }
1142 }
1143 }
1144
1145 boolean newlyCreated = false;
1146 if(null == latch.getPair()) {
1147 try {
1148 Object obj = _factory.makeObject();
1149 latch.setPair(new ObjectTimestampPair(obj));
1150 newlyCreated = true;
1151 } finally {
1152 if (!newlyCreated) {
1153 // object cannot be created
1154 synchronized (this) {
1155 _numInternalProcessing--;
1156 // No need to reset latch - about to throw exception
1157 allocate();
1158 }
1159 }
1160 }
1161 }
1162 // activate & validate the object
1163 try {
1164 _factory.activateObject(latch.getPair().value);
1165 if(_testOnBorrow &&
1166 !_factory.validateObject(latch.getPair().value)) {
1167 throw new Exception("ValidateObject failed");
1168 }
1169 synchronized(this) {
1170 _numInternalProcessing--;
1171 _numActive++;
1172 }
1173 return latch.getPair().value;
1174 }
1175 catch (Throwable e) {
1176 // object cannot be activated or is invalid
1177 try {
1178 _factory.destroyObject(latch.getPair().value);
1179 } catch (Throwable e2) {
1180 // cannot destroy broken object
1181 }
1182 synchronized (this) {
1183 _numInternalProcessing--;
1184 latch.reset();
1185 _allocationQueue.add(0, latch);
1186 allocate();
1187 }
1188 if(newlyCreated) {
1189 throw new NoSuchElementException("Could not create a validated object, cause: " + e.getMessage());
1190 }
1191 else {
1192 continue; // keep looping
1193 }
1194 }
1195 }
1196 }
1197
1198 /**
1199 * Allocate available instances to latches in the allocation queue. Then
1200 * set _mayCreate to true for as many additional latches remaining in queue
1201 * as _maxActive allows.
1202 */
1203 private synchronized void allocate() {
1204 if (isClosed()) return;
1205
1206 // First use any objects in the pool to clear the queue
1207 for (;;) {
1208 if (!_pool.isEmpty() && !_allocationQueue.isEmpty()) {
1209 Latch latch = (Latch) _allocationQueue.removeFirst();
1210 latch.setPair((ObjectTimestampPair) _pool.removeFirst());
1211 _numInternalProcessing++;
1212 synchronized (latch) {
1213 latch.notify();
1214 }
1215 } else {
1216 break;
1217 }
1218 }
1219
1220 // Second utilise any spare capacity to create new objects
1221 for(;;) {
1222 if((!_allocationQueue.isEmpty()) && (_maxActive < 0 || (_numActive + _numInternalProcessing) < _maxActive)) {
1223 Latch latch = (Latch) _allocationQueue.removeFirst();
1224 latch.setMayCreate(true);
1225 _numInternalProcessing++;
1226 synchronized (latch) {
1227 latch.notify();
1228 }
1229 } else {
1230 break;
1231 }
1232 }
1233 }
1234
1235 /**
1236 * <p>Invalidates the given object instance. Decrements the active count
1237 * and destroys the instance.</p>
1238 *
1239 * @param obj instance to invalidate
1240 * @throws Exception if an exception occurs destroying the object
1241 */
1242 public void invalidateObject(Object obj) throws Exception {
1243 try {
1244 if (_factory != null) {
1245 _factory.destroyObject(obj);
1246 }
1247 } finally {
1248 synchronized (this) {
1249 _numActive--;
1250 allocate();
1251 }
1252 }
1253 }
1254
1255 /**
1256 * Clears any objects sitting idle in the pool by removing them from the
1257 * idle instance pool and then invoking the configured
1258 * {@link PoolableObjectFactory#destroyObject(Object)} method on each idle
1259 * instance.
1260 *
1261 * <p> Implementation notes:
1262 * <ul><li>This method does not destroy or effect in any way instances that are
1263 * checked out of the pool when it is invoked.</li>
1264 * <li>Invoking this method does not prevent objects being
1265 * returned to the idle instance pool, even during its execution. It locks
1266 * the pool only during instance removal. Additional instances may be returned
1267 * while removed items are being destroyed.</li></ul></p>
1268 */
1269 public void clear() {
1270 List toDestroy = new ArrayList();
1271
1272 synchronized(this) {
1273 toDestroy.addAll(_pool);
1274 _numInternalProcessing = _numInternalProcessing + _pool._size;
1275 _pool.clear();
1276 }
1277 destroy(toDestroy);
1278 }
1279
1280 /**
1281 * Private method to destroy all the objects in a collection. Assumes
1282 * objects in the collection are instances of ObjectTimestampPair
1283 *
1284 * @param c Collection of objects to destroy
1285 */
1286 private void destroy(Collection c) {
1287 for (Iterator it = c.iterator(); it.hasNext();) {
1288 try {
1289 _factory.destroyObject(((ObjectTimestampPair)(it.next())).value);
1290 } catch(Exception e) {
1291 // ignore error, keep destroying the rest
1292 } finally {
1293 synchronized(this) {
1294 _numInternalProcessing--;
1295 allocate();
1296 }
1297 }
1298 }
1299 }
1300
1301 /**
1302 * Return the number of instances currently borrowed from this pool.
1303 *
1304 * @return the number of instances currently borrowed from this pool
1305 */
1306 public synchronized int getNumActive() {
1307 return _numActive;
1308 }
1309
1310 /**
1311 * Return the number of instances currently idle in this pool.
1312 *
1313 * @return the number of instances currently idle in this pool
1314 */
1315 public synchronized int getNumIdle() {
1316 return _pool.size();
1317 }
1318
1319 /**
1320 * <p>Returns an object instance to the pool.</p>
1321 *
1322 * <p>If {@link #getMaxIdle() maxIdle} is set to a positive value and the number of idle instances
1323 * has reached this value, the returning instance is destroyed.</p>
1324 *
1325 * <p>If {@link #getTestOnReturn() testOnReturn} == true, the returning instance is validated before being returned
1326 * to the idle instance pool. In this case, if validation fails, the instance is destroyed.</p>
1327 *
1328 * <p><strong>Note: </strong> There is no guard to prevent an object
1329 * being returned to the pool multiple times. Clients are expected to
1330 * discard references to returned objects and ensure that an object is not
1331 * returned to the pool multiple times in sequence (i.e., without being
1332 * borrowed again between returns). Violating this contract will result in
1333 * the same object appearing multiple times in the pool and pool counters
1334 * (numActive, numIdle) returning incorrect values.</p>
1335 *
1336 * @param obj instance to return to the pool
1337 */
1338 public void returnObject(Object obj) throws Exception {
1339 try {
1340 addObjectToPool(obj, true);
1341 } catch (Exception e) {
1342 if (_factory != null) {
1343 try {
1344 _factory.destroyObject(obj);
1345 } catch (Exception e2) {
1346 // swallowed
1347 }
1348 // TODO: Correctness here depends on control in addObjectToPool.
1349 // These two methods should be refactored, removing the
1350 // "behavior flag", decrementNumActive, from addObjectToPool.
1351 synchronized(this) {
1352 _numActive--;
1353 allocate();
1354 }
1355 }
1356 }
1357 }
1358
1359 /**
1360 * <p>Adds an object to the pool.</p>
1361 *
1362 * <p>Validates the object if testOnReturn == true and passivates it before returning it to the pool.
1363 * if validation or passivation fails, or maxIdle is set and there is no room in the pool, the instance
1364 * is destroyed.</p>
1365 *
1366 * <p>Calls {@link #allocate()} on successful completion</p>
1367 *
1368 * @param obj instance to add to the pool
1369 * @param decrementNumActive whether or not to decrement the active count
1370 * @throws Exception
1371 */
1372 private void addObjectToPool(Object obj, boolean decrementNumActive) throws Exception {
1373 boolean success = true;
1374 if(_testOnReturn && !(_factory.validateObject(obj))) {
1375 success = false;
1376 } else {
1377 _factory.passivateObject(obj);
1378 }
1379
1380 boolean shouldDestroy = !success;
1381
1382 // Add instance to pool if there is room and it has passed validation
1383 // (if testOnreturn is set)
1384 synchronized (this) {
1385 if (isClosed()) {
1386 shouldDestroy = true;
1387 } else {
1388 if((_maxIdle >= 0) && (_pool.size() >= _maxIdle)) {
1389 shouldDestroy = true;
1390 } else if(success) {
1391 // borrowObject always takes the first element from the queue,
1392 // so for LIFO, push on top, FIFO add to end
1393 if (_lifo) {
1394 _pool.addFirst(new ObjectTimestampPair(obj));
1395 } else {
1396 _pool.addLast(new ObjectTimestampPair(obj));
1397 }
1398 if (decrementNumActive) {
1399 _numActive--;
1400 }
1401 allocate();
1402 }
1403 }
1404 }
1405
1406 // Destroy the instance if necessary
1407 if(shouldDestroy) {
1408 try {
1409 _factory.destroyObject(obj);
1410 } catch(Exception e) {
1411 // ignored
1412 }
1413 // Decrement active count *after* destroy if applicable
1414 if (decrementNumActive) {
1415 synchronized(this) {
1416 _numActive--;
1417 allocate();
1418 }
1419 }
1420 }
1421
1422 }
1423
1424 /**
1425 * Closes the pool. Once the pool is closed, {@link #borrowObject()}
1426 * will fail with IllegalStateException, but {@link #returnObject(Object)} and
1427 * {@link #invalidateObject(Object)} will continue to work. This method does not
1428 * {@link #clear()} the pool. The method is idempotent - that is, it is OK to call it on a closed
1429 * pool.
1430 *
1431 * @throws Exception
1432 */
1433 public void close() throws Exception {
1434 super.close();
1435 synchronized (this) {
1436 clear();
1437 startEvictor(-1L);
1438 }
1439 }
1440
1441 /**
1442 * Sets the {@link PoolableObjectFactory factory} this pool uses
1443 * to create new instances. Trying to change
1444 * the <code>factory</code> while there are borrowed objects will
1445 * throw an {@link IllegalStateException}.
1446 *
1447 * @param factory the {@link PoolableObjectFactory} used to create new instances.
1448 * @throws IllegalStateException when the factory cannot be set at this time
1449 */
1450 public void setFactory(PoolableObjectFactory factory) throws IllegalStateException {
1451 List toDestroy = new ArrayList();
1452 synchronized (this) {
1453 assertOpen();
1454 if(0 < getNumActive()) {
1455 throw new IllegalStateException("Objects are already active");
1456 } else {
1457 toDestroy.addAll(_pool);
1458 _numInternalProcessing = _numInternalProcessing + _pool._size;
1459 _pool.clear();
1460 }
1461 _factory = factory;
1462 }
1463 destroy(toDestroy);
1464 }
1465
1466 /**
1467 * <p>Perform <code>numTests</code> idle object eviction tests, evicting
1468 * examined objects that meet the criteria for eviction. If
1469 * <code>testWhileIdle</code> is true, examined objects are validated
1470 * when visited (and removed if invalid); otherwise only objects that
1471 * have been idle for more than <code>minEvicableIdletimeMillis</code>
1472 * are removed.</p>
1473 *
1474 * <p>Successive activations of this method examine objects in
1475 * in sequence, cycling through objects in oldest-to-youngest order.</p>
1476 *
1477 * @throws Exception if the pool is closed or eviction fails.
1478 */
1479 public void evict() throws Exception {
1480 assertOpen();
1481 synchronized (this) {
1482 if(_pool.isEmpty()) {
1483 return;
1484 }
1485 if (null == _evictionCursor) {
1486 _evictionCursor = (_pool.cursor(_lifo ? _pool.size() : 0));
1487 }
1488 }
1489
1490 for (int i=0,m=getNumTests();i<m;i++) {
1491 final ObjectTimestampPair pair;
1492 synchronized (this) {
1493 if ((_lifo && !_evictionCursor.hasPrevious()) ||
1494 !_lifo && !_evictionCursor.hasNext()) {
1495 _evictionCursor.close();
1496 _evictionCursor = _pool.cursor(_lifo ? _pool.size() : 0);
1497 }
1498
1499 pair = _lifo ?
1500 (ObjectTimestampPair) _evictionCursor.previous() :
1501 (ObjectTimestampPair) _evictionCursor.next();
1502
1503 _evictionCursor.remove();
1504 _numInternalProcessing++;
1505 }
1506
1507 boolean removeObject = false;
1508 final long idleTimeMilis = System.currentTimeMillis() - pair.tstamp;
1509 if ((getMinEvictableIdleTimeMillis() > 0) &&
1510 (idleTimeMilis > getMinEvictableIdleTimeMillis())) {
1511 removeObject = true;
1512 } else if ((getSoftMinEvictableIdleTimeMillis() > 0) &&
1513 (idleTimeMilis > getSoftMinEvictableIdleTimeMillis()) &&
1514 ((getNumIdle() + 1)> getMinIdle())) { // +1 accounts for object we are processing
1515 removeObject = true;
1516 }
1517 if(getTestWhileIdle() && !removeObject) {
1518 boolean active = false;
1519 try {
1520 _factory.activateObject(pair.value);
1521 active = true;
1522 } catch(Exception e) {
1523 removeObject=true;
1524 }
1525 if(active) {
1526 if(!_factory.validateObject(pair.value)) {
1527 removeObject=true;
1528 } else {
1529 try {
1530 _factory.passivateObject(pair.value);
1531 } catch(Exception e) {
1532 removeObject=true;
1533 }
1534 }
1535 }
1536 }
1537
1538 if (removeObject) {
1539 try {
1540 _factory.destroyObject(pair.value);
1541 } catch(Exception e) {
1542 // ignored
1543 }
1544 }
1545 synchronized (this) {
1546 if(!removeObject) {
1547 _evictionCursor.add(pair);
1548 if (_lifo) {
1549 // Skip over the element we just added back
1550 _evictionCursor.previous();
1551 }
1552 }
1553 _numInternalProcessing--;
1554 }
1555 }
1556 }
1557
1558 /**
1559 * Check to see if we are below our minimum number of objects
1560 * if so enough to bring us back to our minimum.
1561 *
1562 * @throws Exception when {@link #addObject()} fails.
1563 */
1564 private void ensureMinIdle() throws Exception {
1565 // this method isn't synchronized so the
1566 // calculateDeficit is done at the beginning
1567 // as a loop limit and a second time inside the loop
1568 // to stop when another thread already returned the
1569 // needed objects
1570 int objectDeficit = calculateDeficit(false);
1571 for ( int j = 0 ; j < objectDeficit && calculateDeficit(true) > 0 ; j++ ) {
1572 try {
1573 addObject();
1574 } finally {
1575 synchronized (this) {
1576 _numInternalProcessing--;
1577 allocate();
1578 }
1579 }
1580 }
1581 }
1582
1583 /**
1584 * This returns the number of objects to create during the pool
1585 * sustain cycle. This will ensure that the minimum number of idle
1586 * instances is maintained without going past the maxActive value.
1587 *
1588 * @param incrementInternal - Should the count of objects currently under
1589 * some form of internal processing be
1590 * incremented?
1591 * @return The number of objects to be created
1592 */
1593 private synchronized int calculateDeficit(boolean incrementInternal) {
1594 int objectDeficit = getMinIdle() - getNumIdle();
1595 if (_maxActive > 0) {
1596 int growLimit = Math.max(0,
1597 getMaxActive() - getNumActive() - getNumIdle() - _numInternalProcessing);
1598 objectDeficit = Math.min(objectDeficit, growLimit);
1599 }
1600 if (incrementInternal && objectDeficit >0) {
1601 _numInternalProcessing++;
1602 }
1603 return objectDeficit;
1604 }
1605
1606 /**
1607 * Create an object, and place it into the pool.
1608 * addObject() is useful for "pre-loading" a pool with idle objects.
1609 */
1610 public void addObject() throws Exception {
1611 assertOpen();
1612 if (_factory == null) {
1613 throw new IllegalStateException("Cannot add objects without a factory.");
1614 }
1615 Object obj = _factory.makeObject();
1616 try {
1617 assertOpen();
1618 addObjectToPool(obj, false);
1619 } catch (IllegalStateException ex) { // Pool closed
1620 try {
1621 _factory.destroyObject(obj);
1622 } catch (Exception ex2) {
1623 // swallow
1624 }
1625 throw ex;
1626 }
1627 }
1628
1629 //--- non-public methods ----------------------------------------
1630
1631 /**
1632 * Start the eviction thread or service, or when
1633 * <i>delay</i> is non-positive, stop it
1634 * if it is already running.
1635 *
1636 * @param delay milliseconds between evictor runs.
1637 */
1638 protected synchronized void startEvictor(long delay) {
1639 if(null != _evictor) {
1640 EvictionTimer.cancel(_evictor);
1641 _evictor = null;
1642 }
1643 if(delay > 0) {
1644 _evictor = new Evictor();
1645 EvictionTimer.schedule(_evictor, delay, delay);
1646 }
1647 }
1648
1649 /**
1650 * Returns pool info including {@link #getNumActive()}, {@link #getNumIdle()}
1651 * and a list of objects idle in the pool with their idle times.
1652 *
1653 * @return string containing debug information
1654 */
1655 synchronized String debugInfo() {
1656 StringBuffer buf = new StringBuffer();
1657 buf.append("Active: ").append(getNumActive()).append("\n");
1658 buf.append("Idle: ").append(getNumIdle()).append("\n");
1659 buf.append("Idle Objects:\n");
1660 Iterator it = _pool.iterator();
1661 long time = System.currentTimeMillis();
1662 while(it.hasNext()) {
1663 ObjectTimestampPair pair = (ObjectTimestampPair)(it.next());
1664 buf.append("\t").append(pair.value).append("\t").append(time - pair.tstamp).append("\n");
1665 }
1666 return buf.toString();
1667 }
1668
1669 /**
1670 * Returns the number of tests to be performed in an Evictor run,
1671 * based on the current value of <code>numTestsPerEvictionRun</code>
1672 * and the number of idle instances in the pool.
1673 *
1674 * @see #setNumTestsPerEvictionRun
1675 * @return the number of tests for the Evictor to run
1676 */
1677 private int getNumTests() {
1678 if(_numTestsPerEvictionRun >= 0) {
1679 return Math.min(_numTestsPerEvictionRun, _pool.size());
1680 } else {
1681 return(int)(Math.ceil(_pool.size()/Math.abs((double)_numTestsPerEvictionRun)));
1682 }
1683 }
1684
1685 //--- inner classes ----------------------------------------------
1686
1687 /**
1688 * The idle object evictor {@link TimerTask}.
1689 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1690 */
1691 private class Evictor extends TimerTask {
1692 /**
1693 * Run pool maintenance. Evict objects qualifying for eviction and then
1694 * invoke {@link GenericObjectPool#ensureMinIdle()}.
1695 */
1696 public void run() {
1697 try {
1698 evict();
1699 } catch(Exception e) {
1700 // ignored
1701 } catch(OutOfMemoryError oome) {
1702 // Log problem but give evictor thread a chance to continue in
1703 // case error is recoverable
1704 oome.printStackTrace(System.err);
1705 }
1706 try {
1707 ensureMinIdle();
1708 } catch(Exception e) {
1709 // ignored
1710 }
1711 }
1712 }
1713
1714 /**
1715 * A simple "struct" encapsulating the
1716 * configuration information for a {@link GenericObjectPool}.
1717 * @see GenericObjectPool#GenericObjectPool(org.apache.commons.pool.PoolableObjectFactory,
1718 * org.apache.commons.pool.impl.GenericObjectPool.Config)
1719 * @see GenericObjectPool#setConfig
1720 */
1721 public static class Config {
1722 /**
1723 * @see GenericObjectPool#setMaxIdle
1724 */
1725 public int maxIdle = GenericObjectPool.DEFAULT_MAX_IDLE;
1726 /**
1727 * @see GenericObjectPool#setMinIdle
1728 */
1729 public int minIdle = GenericObjectPool.DEFAULT_MIN_IDLE;
1730 /**
1731 * @see GenericObjectPool#setMaxActive
1732 */
1733 public int maxActive = GenericObjectPool.DEFAULT_MAX_ACTIVE;
1734 /**
1735 * @see GenericObjectPool#setMaxWait
1736 */
1737 public long maxWait = GenericObjectPool.DEFAULT_MAX_WAIT;
1738 /**
1739 * @see GenericObjectPool#setWhenExhaustedAction
1740 */
1741 public byte whenExhaustedAction = GenericObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
1742 /**
1743 * @see GenericObjectPool#setTestOnBorrow
1744 */
1745 public boolean testOnBorrow = GenericObjectPool.DEFAULT_TEST_ON_BORROW;
1746 /**
1747 * @see GenericObjectPool#setTestOnReturn
1748 */
1749 public boolean testOnReturn = GenericObjectPool.DEFAULT_TEST_ON_RETURN;
1750 /**
1751 * @see GenericObjectPool#setTestWhileIdle
1752 */
1753 public boolean testWhileIdle = GenericObjectPool.DEFAULT_TEST_WHILE_IDLE;
1754 /**
1755 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1756 */
1757 public long timeBetweenEvictionRunsMillis = GenericObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1758 /**
1759 * @see GenericObjectPool#setNumTestsPerEvictionRun
1760 */
1761 public int numTestsPerEvictionRun = GenericObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1762 /**
1763 * @see GenericObjectPool#setMinEvictableIdleTimeMillis
1764 */
1765 public long minEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1766 /**
1767 * @see GenericObjectPool#setSoftMinEvictableIdleTimeMillis
1768 */
1769 public long softMinEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1770 /**
1771 * @see GenericObjectPool#setLifo
1772 */
1773 public boolean lifo = GenericObjectPool.DEFAULT_LIFO;
1774
1775 }
1776
1777 /**
1778 * Latch used to control allocation order of objects to threads to ensure
1779 * fairness. That is, objects are allocated to threads in the order that
1780 * threads request objects.
1781 */
1782 private static final class Latch {
1783
1784 /** object timestamp pair allocated to this latch */
1785 private ObjectTimestampPair _pair;
1786
1787 /** Wheter or not this latch may create an object instance */
1788 private boolean _mayCreate = false;
1789
1790 /**
1791 * Returns ObjectTimestampPair allocated to this latch
1792 * @return ObjectTimestampPair allocated to this latch
1793 */
1794 private synchronized ObjectTimestampPair getPair() {
1795 return _pair;
1796 }
1797
1798 /**
1799 * Sets ObjectTimestampPair on this latch
1800 * @param pair ObjectTimestampPair allocated to this latch
1801 */
1802 private synchronized void setPair(ObjectTimestampPair pair) {
1803 _pair = pair;
1804 }
1805
1806 /**
1807 * Whether or not this latch may create an object instance
1808 * @return true if this latch has an instance creation permit
1809 */
1810 private synchronized boolean mayCreate() {
1811 return _mayCreate;
1812 }
1813
1814 /**
1815 * Sets the mayCreate property
1816 * @param mayCreate new value for mayCreate
1817 */
1818 private synchronized void setMayCreate(boolean mayCreate) {
1819 _mayCreate = mayCreate;
1820 }
1821
1822 /**
1823 * Reset the latch data. Used when an allocation fails and the latch
1824 * needs to be re-added to the queue.
1825 */
1826 private synchronized void reset() {
1827 _pair = null;
1828 _mayCreate = false;
1829 }
1830 }
1831
1832
1833 //--- private attributes ---------------------------------------
1834
1835 /**
1836 * The cap on the number of idle instances in the pool.
1837 * @see #setMaxIdle
1838 * @see #getMaxIdle
1839 */
1840 private int _maxIdle = DEFAULT_MAX_IDLE;
1841
1842 /**
1843 * The cap on the minimum number of idle instances in the pool.
1844 * @see #setMinIdle
1845 * @see #getMinIdle
1846 */
1847 private int _minIdle = DEFAULT_MIN_IDLE;
1848
1849 /**
1850 * The cap on the total number of active instances from the pool.
1851 * @see #setMaxActive
1852 * @see #getMaxActive
1853 */
1854 private int _maxActive = DEFAULT_MAX_ACTIVE;
1855
1856 /**
1857 * The maximum amount of time (in millis) the
1858 * {@link #borrowObject} method should block before throwing
1859 * an exception when the pool is exhausted and the
1860 * {@link #getWhenExhaustedAction "when exhausted" action} is
1861 * {@link #WHEN_EXHAUSTED_BLOCK}.
1862 *
1863 * When less than or equal to 0, the {@link #borrowObject} method
1864 * may block indefinitely.
1865 *
1866 * @see #setMaxWait
1867 * @see #getMaxWait
1868 * @see #WHEN_EXHAUSTED_BLOCK
1869 * @see #setWhenExhaustedAction
1870 * @see #getWhenExhaustedAction
1871 */
1872 private long _maxWait = DEFAULT_MAX_WAIT;
1873
1874 /**
1875 * The action to take when the {@link #borrowObject} method
1876 * is invoked when the pool is exhausted (the maximum number
1877 * of "active" objects has been reached).
1878 *
1879 * @see #WHEN_EXHAUSTED_BLOCK
1880 * @see #WHEN_EXHAUSTED_FAIL
1881 * @see #WHEN_EXHAUSTED_GROW
1882 * @see #DEFAULT_WHEN_EXHAUSTED_ACTION
1883 * @see #setWhenExhaustedAction
1884 * @see #getWhenExhaustedAction
1885 */
1886 private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
1887
1888 /**
1889 * When <tt>true</tt>, objects will be
1890 * {@link PoolableObjectFactory#validateObject validated}
1891 * before being returned by the {@link #borrowObject}
1892 * method. If the object fails to validate,
1893 * it will be dropped from the pool, and we will attempt
1894 * to borrow another.
1895 *
1896 * @see #setTestOnBorrow
1897 * @see #getTestOnBorrow
1898 */
1899 private volatile boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
1900
1901 /**
1902 * When <tt>true</tt>, objects will be
1903 * {@link PoolableObjectFactory#validateObject validated}
1904 * before being returned to the pool within the
1905 * {@link #returnObject}.
1906 *
1907 * @see #getTestOnReturn
1908 * @see #setTestOnReturn
1909 */
1910 private volatile boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
1911
1912 /**
1913 * When <tt>true</tt>, objects will be
1914 * {@link PoolableObjectFactory#validateObject validated}
1915 * by the idle object evictor (if any). If an object
1916 * fails to validate, it will be dropped from the pool.
1917 *
1918 * @see #setTestWhileIdle
1919 * @see #getTestWhileIdle
1920 * @see #getTimeBetweenEvictionRunsMillis
1921 * @see #setTimeBetweenEvictionRunsMillis
1922 */
1923 private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
1924
1925 /**
1926 * The number of milliseconds to sleep between runs of the
1927 * idle object evictor thread.
1928 * When non-positive, no idle object evictor thread will be
1929 * run.
1930 *
1931 * @see #setTimeBetweenEvictionRunsMillis
1932 * @see #getTimeBetweenEvictionRunsMillis
1933 */
1934 private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1935
1936 /**
1937 * The max number of objects to examine during each run of the
1938 * idle object evictor thread (if any).
1939 * <p>
1940 * When a negative value is supplied, <tt>ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})</tt>
1941 * tests will be run. I.e., when the value is <i>-n</i>, roughly one <i>n</i>th of the
1942 * idle objects will be tested per run.
1943 *
1944 * @see #setNumTestsPerEvictionRun
1945 * @see #getNumTestsPerEvictionRun
1946 * @see #getTimeBetweenEvictionRunsMillis
1947 * @see #setTimeBetweenEvictionRunsMillis
1948 */
1949 private int _numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1950
1951 /**
1952 * The minimum amount of time an object may sit idle in the pool
1953 * before it is eligible for eviction by the idle object evictor
1954 * (if any).
1955 * When non-positive, no objects will be evicted from the pool
1956 * due to idle time alone.
1957 *
1958 * @see #setMinEvictableIdleTimeMillis
1959 * @see #getMinEvictableIdleTimeMillis
1960 * @see #getTimeBetweenEvictionRunsMillis
1961 * @see #setTimeBetweenEvictionRunsMillis
1962 */
1963 private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1964
1965 /**
1966 * The minimum amount of time an object may sit idle in the pool
1967 * before it is eligible for eviction by the idle object evictor
1968 * (if any), with the extra condition that at least
1969 * "minIdle" amount of object remain in the pool.
1970 * When non-positive, no objects will be evicted from the pool
1971 * due to idle time alone.
1972 *
1973 * @see #setSoftMinEvictableIdleTimeMillis
1974 * @see #getSoftMinEvictableIdleTimeMillis
1975 */
1976 private long _softMinEvictableIdleTimeMillis = DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1977
1978 /** Whether or not the pool behaves as a LIFO queue (last in first out) */
1979 private boolean _lifo = DEFAULT_LIFO;
1980
1981 /** My pool. */
1982 private CursorableLinkedList _pool = null;
1983
1984 /** Eviction cursor - keeps track of idle object evictor position */
1985 private CursorableLinkedList.Cursor _evictionCursor = null;
1986
1987 /** My {@link PoolableObjectFactory}. */
1988 private PoolableObjectFactory _factory = null;
1989
1990 /**
1991 * The number of objects {@link #borrowObject} borrowed
1992 * from the pool, but not yet returned.
1993 */
1994 private int _numActive = 0;
1995
1996 /**
1997 * My idle object eviction {@link TimerTask}, if any.
1998 */
1999 private Evictor _evictor = null;
2000
2001 /**
2002 * The number of objects subject to some form of internal processing
2003 * (usually creation or destruction) that should be included in the total
2004 * number of objects but are neither active nor idle.
2005 */
2006 private int _numInternalProcessing = 0;
2007
2008 /**
2009 * Used to track the order in which threads call {@link #borrowObject()} so
2010 * that objects can be allocated in the order in which the threads requested
2011 * them.
2012 */
2013 private LinkedList _allocationQueue = new LinkedList();
2014
2015 }