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: 791907 $ $Date: 2009-07-07 12:56:33 -0400 (Tue, 07 Jul 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 allocate hasn't already assigned an object
1080 // in a different thread
1081 if (latch.getPair() == null) {
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
1091 if (latch.getPair() != null) {
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 if (latch.getPair() == null) {
1102 if(maxWait <= 0) {
1103 latch.wait();
1104 } else {
1105 // this code may be executed again after a notify then continue cycle
1106 // so, need to calculate the amount of time to wait
1107 final long elapsed = (System.currentTimeMillis() - starttime);
1108 final long waitTime = maxWait - elapsed;
1109 if (waitTime > 0)
1110 {
1111 latch.wait(waitTime);
1112 }
1113 }
1114 } else {
1115 break;
1116 }
1117 }
1118 } catch(InterruptedException e) {
1119 Thread.currentThread().interrupt();
1120 throw e;
1121 }
1122 if(maxWait > 0 && ((System.currentTimeMillis() - starttime) >= maxWait)) {
1123 synchronized(this) {
1124 // Make sure allocate hasn't already assigned an object
1125 // in a different thread
1126 if (latch.getPair() == null) {
1127 // Remove latch from the allocation queue
1128 _allocationQueue.remove(latch);
1129 } else {
1130 break;
1131 }
1132 }
1133 throw new NoSuchElementException("Timeout waiting for idle object");
1134 } else {
1135 continue; // keep looping
1136 }
1137 default:
1138 throw new IllegalArgumentException("WhenExhaustedAction property " + whenExhaustedAction +
1139 " not recognized.");
1140 }
1141 }
1142 }
1143
1144 boolean newlyCreated = false;
1145 if(null == latch.getPair()) {
1146 try {
1147 Object obj = _factory.makeObject();
1148 latch.setPair(new ObjectTimestampPair(obj));
1149 newlyCreated = true;
1150 } finally {
1151 if (!newlyCreated) {
1152 // object cannot be created
1153 synchronized (this) {
1154 _numInternalProcessing--;
1155 // No need to reset latch - about to throw exception
1156 allocate();
1157 }
1158 }
1159 }
1160 }
1161 // activate & validate the object
1162 try {
1163 _factory.activateObject(latch.getPair().value);
1164 if(_testOnBorrow &&
1165 !_factory.validateObject(latch.getPair().value)) {
1166 throw new Exception("ValidateObject failed");
1167 }
1168 synchronized(this) {
1169 _numInternalProcessing--;
1170 _numActive++;
1171 }
1172 return latch.getPair().value;
1173 }
1174 catch (Throwable e) {
1175 // object cannot be activated or is invalid
1176 try {
1177 _factory.destroyObject(latch.getPair().value);
1178 } catch (Throwable e2) {
1179 // cannot destroy broken object
1180 }
1181 synchronized (this) {
1182 _numInternalProcessing--;
1183 latch.reset();
1184 _allocationQueue.add(0, latch);
1185 allocate();
1186 }
1187 if(newlyCreated) {
1188 throw new NoSuchElementException("Could not create a validated object, cause: " + e.getMessage());
1189 }
1190 else {
1191 continue; // keep looping
1192 }
1193 }
1194 }
1195 }
1196
1197 /**
1198 * Allocate available instances to latches in the allocation queue. Then
1199 * set _mayCreate to true for as many additional latches remaining in queue
1200 * as _maxActive allows.
1201 */
1202 private synchronized void allocate() {
1203 if (isClosed()) return;
1204
1205 // First use any objects in the pool to clear the queue
1206 for (;;) {
1207 if (!_pool.isEmpty() && !_allocationQueue.isEmpty()) {
1208 Latch latch = (Latch) _allocationQueue.removeFirst();
1209 latch.setPair((ObjectTimestampPair) _pool.removeFirst());
1210 _numInternalProcessing++;
1211 synchronized (latch) {
1212 latch.notify();
1213 }
1214 } else {
1215 break;
1216 }
1217 }
1218
1219 // Second utilise any spare capacity to create new objects
1220 for(;;) {
1221 if((!_allocationQueue.isEmpty()) && (_maxActive < 0 || (_numActive + _numInternalProcessing) < _maxActive)) {
1222 Latch latch = (Latch) _allocationQueue.removeFirst();
1223 latch.setMayCreate(true);
1224 _numInternalProcessing++;
1225 synchronized (latch) {
1226 latch.notify();
1227 }
1228 } else {
1229 break;
1230 }
1231 }
1232 }
1233
1234 /**
1235 * <p>Invalidates the given object instance. Decrements the active count
1236 * and destroys the instance.</p>
1237 *
1238 * @param obj instance to invalidate
1239 * @throws Exception if an exception occurs destroying the object
1240 */
1241 public void invalidateObject(Object obj) throws Exception {
1242 try {
1243 if (_factory != null) {
1244 _factory.destroyObject(obj);
1245 }
1246 } finally {
1247 synchronized (this) {
1248 _numActive--;
1249 allocate();
1250 }
1251 }
1252 }
1253
1254 /**
1255 * Clears any objects sitting idle in the pool by removing them from the
1256 * idle instance pool and then invoking the configured
1257 * {@link PoolableObjectFactory#destroyObject(Object)} method on each idle
1258 * instance.
1259 *
1260 * <p> Implementation notes:
1261 * <ul><li>This method does not destroy or effect in any way instances that are
1262 * checked out of the pool when it is invoked.</li>
1263 * <li>Invoking this method does not prevent objects being
1264 * returned to the idle instance pool, even during its execution. It locks
1265 * the pool only during instance removal. Additional instances may be returned
1266 * while removed items are being destroyed.</li></ul></p>
1267 */
1268 public void clear() {
1269 List toDestroy = new ArrayList();
1270
1271 synchronized(this) {
1272 toDestroy.addAll(_pool);
1273 _numInternalProcessing = _numInternalProcessing + _pool._size;
1274 _pool.clear();
1275 }
1276 destroy(toDestroy);
1277 }
1278
1279 /**
1280 * Private method to destroy all the objects in a collection. Assumes
1281 * objects in the collection are instances of ObjectTimestampPair
1282 *
1283 * @param c Collection of objects to destroy
1284 */
1285 private void destroy(Collection c) {
1286 for (Iterator it = c.iterator(); it.hasNext();) {
1287 try {
1288 _factory.destroyObject(((ObjectTimestampPair)(it.next())).value);
1289 } catch(Exception e) {
1290 // ignore error, keep destroying the rest
1291 } finally {
1292 synchronized(this) {
1293 _numInternalProcessing--;
1294 allocate();
1295 }
1296 }
1297 }
1298 }
1299
1300 /**
1301 * Return the number of instances currently borrowed from this pool.
1302 *
1303 * @return the number of instances currently borrowed from this pool
1304 */
1305 public synchronized int getNumActive() {
1306 return _numActive;
1307 }
1308
1309 /**
1310 * Return the number of instances currently idle in this pool.
1311 *
1312 * @return the number of instances currently idle in this pool
1313 */
1314 public synchronized int getNumIdle() {
1315 return _pool.size();
1316 }
1317
1318 /**
1319 * <p>Returns an object instance to the pool.</p>
1320 *
1321 * <p>If {@link #getMaxIdle() maxIdle} is set to a positive value and the number of idle instances
1322 * has reached this value, the returning instance is destroyed.</p>
1323 *
1324 * <p>If {@link #getTestOnReturn() testOnReturn} == true, the returning instance is validated before being returned
1325 * to the idle instance pool. In this case, if validation fails, the instance is destroyed.</p>
1326 *
1327 * <p><strong>Note: </strong> There is no guard to prevent an object
1328 * being returned to the pool multiple times. Clients are expected to
1329 * discard references to returned objects and ensure that an object is not
1330 * returned to the pool multiple times in sequence (i.e., without being
1331 * borrowed again between returns). Violating this contract will result in
1332 * the same object appearing multiple times in the pool and pool counters
1333 * (numActive, numIdle) returning incorrect values.</p>
1334 *
1335 * @param obj instance to return to the pool
1336 */
1337 public void returnObject(Object obj) throws Exception {
1338 try {
1339 addObjectToPool(obj, true);
1340 } catch (Exception e) {
1341 if (_factory != null) {
1342 try {
1343 _factory.destroyObject(obj);
1344 } catch (Exception e2) {
1345 // swallowed
1346 }
1347 // TODO: Correctness here depends on control in addObjectToPool.
1348 // These two methods should be refactored, removing the
1349 // "behavior flag", decrementNumActive, from addObjectToPool.
1350 synchronized(this) {
1351 _numActive--;
1352 allocate();
1353 }
1354 }
1355 }
1356 }
1357
1358 /**
1359 * <p>Adds an object to the pool.</p>
1360 *
1361 * <p>Validates the object if testOnReturn == true and passivates it before returning it to the pool.
1362 * if validation or passivation fails, or maxIdle is set and there is no room in the pool, the instance
1363 * is destroyed.</p>
1364 *
1365 * <p>Calls {@link #allocate()} on successful completion</p>
1366 *
1367 * @param obj instance to add to the pool
1368 * @param decrementNumActive whether or not to decrement the active count
1369 * @throws Exception
1370 */
1371 private void addObjectToPool(Object obj, boolean decrementNumActive) throws Exception {
1372 boolean success = true;
1373 if(_testOnReturn && !(_factory.validateObject(obj))) {
1374 success = false;
1375 } else {
1376 _factory.passivateObject(obj);
1377 }
1378
1379 boolean shouldDestroy = !success;
1380
1381 // Add instance to pool if there is room and it has passed validation
1382 // (if testOnreturn is set)
1383 synchronized (this) {
1384 if (isClosed()) {
1385 shouldDestroy = true;
1386 } else {
1387 if((_maxIdle >= 0) && (_pool.size() >= _maxIdle)) {
1388 shouldDestroy = true;
1389 } else if(success) {
1390 // borrowObject always takes the first element from the queue,
1391 // so for LIFO, push on top, FIFO add to end
1392 if (_lifo) {
1393 _pool.addFirst(new ObjectTimestampPair(obj));
1394 } else {
1395 _pool.addLast(new ObjectTimestampPair(obj));
1396 }
1397 if (decrementNumActive) {
1398 _numActive--;
1399 }
1400 allocate();
1401 }
1402 }
1403 }
1404
1405 // Destroy the instance if necessary
1406 if(shouldDestroy) {
1407 try {
1408 _factory.destroyObject(obj);
1409 } catch(Exception e) {
1410 // ignored
1411 }
1412 // Decrement active count *after* destroy if applicable
1413 if (decrementNumActive) {
1414 synchronized(this) {
1415 _numActive--;
1416 allocate();
1417 }
1418 }
1419 }
1420
1421 }
1422
1423 /**
1424 * Closes the pool. Once the pool is closed, {@link #borrowObject()}
1425 * will fail with IllegalStateException, but {@link #returnObject(Object)} and
1426 * {@link #invalidateObject(Object)} will continue to work. This method does not
1427 * {@link #clear()} the pool. The method is idempotent - that is, it is OK to call it on a closed
1428 * pool.
1429 *
1430 * @throws Exception
1431 */
1432 public void close() throws Exception {
1433 super.close();
1434 synchronized (this) {
1435 clear();
1436 startEvictor(-1L);
1437 }
1438 }
1439
1440 /**
1441 * Sets the {@link PoolableObjectFactory factory} this pool uses
1442 * to create new instances. Trying to change
1443 * the <code>factory</code> while there are borrowed objects will
1444 * throw an {@link IllegalStateException}.
1445 *
1446 * @param factory the {@link PoolableObjectFactory} used to create new instances.
1447 * @throws IllegalStateException when the factory cannot be set at this time
1448 */
1449 public void setFactory(PoolableObjectFactory factory) throws IllegalStateException {
1450 List toDestroy = new ArrayList();
1451 synchronized (this) {
1452 assertOpen();
1453 if(0 < getNumActive()) {
1454 throw new IllegalStateException("Objects are already active");
1455 } else {
1456 toDestroy.addAll(_pool);
1457 _numInternalProcessing = _numInternalProcessing + _pool._size;
1458 _pool.clear();
1459 }
1460 _factory = factory;
1461 }
1462 destroy(toDestroy);
1463 }
1464
1465 /**
1466 * <p>Perform <code>numTests</code> idle object eviction tests, evicting
1467 * examined objects that meet the criteria for eviction. If
1468 * <code>testWhileIdle</code> is true, examined objects are validated
1469 * when visited (and removed if invalid); otherwise only objects that
1470 * have been idle for more than <code>minEvicableIdletimeMillis</code>
1471 * are removed.</p>
1472 *
1473 * <p>Successive activations of this method examine objects in
1474 * in sequence, cycling through objects in oldest-to-youngest order.</p>
1475 *
1476 * @throws Exception if the pool is closed or eviction fails.
1477 */
1478 public void evict() throws Exception {
1479 assertOpen();
1480 synchronized (this) {
1481 if(_pool.isEmpty()) {
1482 return;
1483 }
1484 if (null == _evictionCursor) {
1485 _evictionCursor = (_pool.cursor(_lifo ? _pool.size() : 0));
1486 }
1487 }
1488
1489 for (int i=0,m=getNumTests();i<m;i++) {
1490 final ObjectTimestampPair pair;
1491 synchronized (this) {
1492 if ((_lifo && !_evictionCursor.hasPrevious()) ||
1493 !_lifo && !_evictionCursor.hasNext()) {
1494 _evictionCursor.close();
1495 _evictionCursor = _pool.cursor(_lifo ? _pool.size() : 0);
1496 }
1497
1498 pair = _lifo ?
1499 (ObjectTimestampPair) _evictionCursor.previous() :
1500 (ObjectTimestampPair) _evictionCursor.next();
1501
1502 _evictionCursor.remove();
1503 _numInternalProcessing++;
1504 }
1505
1506 boolean removeObject = false;
1507 final long idleTimeMilis = System.currentTimeMillis() - pair.tstamp;
1508 if ((getMinEvictableIdleTimeMillis() > 0) &&
1509 (idleTimeMilis > getMinEvictableIdleTimeMillis())) {
1510 removeObject = true;
1511 } else if ((getSoftMinEvictableIdleTimeMillis() > 0) &&
1512 (idleTimeMilis > getSoftMinEvictableIdleTimeMillis()) &&
1513 ((getNumIdle() + 1)> getMinIdle())) { // +1 accounts for object we are processing
1514 removeObject = true;
1515 }
1516 if(getTestWhileIdle() && !removeObject) {
1517 boolean active = false;
1518 try {
1519 _factory.activateObject(pair.value);
1520 active = true;
1521 } catch(Exception e) {
1522 removeObject=true;
1523 }
1524 if(active) {
1525 if(!_factory.validateObject(pair.value)) {
1526 removeObject=true;
1527 } else {
1528 try {
1529 _factory.passivateObject(pair.value);
1530 } catch(Exception e) {
1531 removeObject=true;
1532 }
1533 }
1534 }
1535 }
1536
1537 if (removeObject) {
1538 try {
1539 _factory.destroyObject(pair.value);
1540 } catch(Exception e) {
1541 // ignored
1542 }
1543 }
1544 synchronized (this) {
1545 if(!removeObject) {
1546 _evictionCursor.add(pair);
1547 if (_lifo) {
1548 // Skip over the element we just added back
1549 _evictionCursor.previous();
1550 }
1551 }
1552 _numInternalProcessing--;
1553 }
1554 }
1555 }
1556
1557 /**
1558 * Check to see if we are below our minimum number of objects
1559 * if so enough to bring us back to our minimum.
1560 *
1561 * @throws Exception when {@link #addObject()} fails.
1562 */
1563 private void ensureMinIdle() throws Exception {
1564 // this method isn't synchronized so the
1565 // calculateDeficit is done at the beginning
1566 // as a loop limit and a second time inside the loop
1567 // to stop when another thread already returned the
1568 // needed objects
1569 int objectDeficit = calculateDeficit(false);
1570 for ( int j = 0 ; j < objectDeficit && calculateDeficit(true) > 0 ; j++ ) {
1571 try {
1572 addObject();
1573 } finally {
1574 synchronized (this) {
1575 _numInternalProcessing--;
1576 allocate();
1577 }
1578 }
1579 }
1580 }
1581
1582 /**
1583 * This returns the number of objects to create during the pool
1584 * sustain cycle. This will ensure that the minimum number of idle
1585 * instances is maintained without going past the maxActive value.
1586 *
1587 * @param incrementInternal - Should the count of objects currently under
1588 * some form of internal processing be
1589 * incremented?
1590 * @return The number of objects to be created
1591 */
1592 private synchronized int calculateDeficit(boolean incrementInternal) {
1593 int objectDeficit = getMinIdle() - getNumIdle();
1594 if (_maxActive > 0) {
1595 int growLimit = Math.max(0,
1596 getMaxActive() - getNumActive() - getNumIdle() - _numInternalProcessing);
1597 objectDeficit = Math.min(objectDeficit, growLimit);
1598 }
1599 if (incrementInternal && objectDeficit >0) {
1600 _numInternalProcessing++;
1601 }
1602 return objectDeficit;
1603 }
1604
1605 /**
1606 * Create an object, and place it into the pool.
1607 * addObject() is useful for "pre-loading" a pool with idle objects.
1608 */
1609 public void addObject() throws Exception {
1610 assertOpen();
1611 if (_factory == null) {
1612 throw new IllegalStateException("Cannot add objects without a factory.");
1613 }
1614 Object obj = _factory.makeObject();
1615 try {
1616 assertOpen();
1617 addObjectToPool(obj, false);
1618 } catch (IllegalStateException ex) { // Pool closed
1619 try {
1620 _factory.destroyObject(obj);
1621 } catch (Exception ex2) {
1622 // swallow
1623 }
1624 throw ex;
1625 }
1626 }
1627
1628 //--- non-public methods ----------------------------------------
1629
1630 /**
1631 * Start the eviction thread or service, or when
1632 * <i>delay</i> is non-positive, stop it
1633 * if it is already running.
1634 *
1635 * @param delay milliseconds between evictor runs.
1636 */
1637 protected synchronized void startEvictor(long delay) {
1638 if(null != _evictor) {
1639 EvictionTimer.cancel(_evictor);
1640 _evictor = null;
1641 }
1642 if(delay > 0) {
1643 _evictor = new Evictor();
1644 EvictionTimer.schedule(_evictor, delay, delay);
1645 }
1646 }
1647
1648 /**
1649 * Returns pool info including {@link #getNumActive()}, {@link #getNumIdle()}
1650 * and a list of objects idle in the pool with their idle times.
1651 *
1652 * @return string containing debug information
1653 */
1654 synchronized String debugInfo() {
1655 StringBuffer buf = new StringBuffer();
1656 buf.append("Active: ").append(getNumActive()).append("\n");
1657 buf.append("Idle: ").append(getNumIdle()).append("\n");
1658 buf.append("Idle Objects:\n");
1659 Iterator it = _pool.iterator();
1660 long time = System.currentTimeMillis();
1661 while(it.hasNext()) {
1662 ObjectTimestampPair pair = (ObjectTimestampPair)(it.next());
1663 buf.append("\t").append(pair.value).append("\t").append(time - pair.tstamp).append("\n");
1664 }
1665 return buf.toString();
1666 }
1667
1668 /**
1669 * Returns the number of tests to be performed in an Evictor run,
1670 * based on the current value of <code>numTestsPerEvictionRun</code>
1671 * and the number of idle instances in the pool.
1672 *
1673 * @see #setNumTestsPerEvictionRun
1674 * @return the number of tests for the Evictor to run
1675 */
1676 private int getNumTests() {
1677 if(_numTestsPerEvictionRun >= 0) {
1678 return Math.min(_numTestsPerEvictionRun, _pool.size());
1679 } else {
1680 return(int)(Math.ceil(_pool.size()/Math.abs((double)_numTestsPerEvictionRun)));
1681 }
1682 }
1683
1684 //--- inner classes ----------------------------------------------
1685
1686 /**
1687 * The idle object evictor {@link TimerTask}.
1688 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1689 */
1690 private class Evictor extends TimerTask {
1691 /**
1692 * Run pool maintenance. Evict objects qualifying for eviction and then
1693 * invoke {@link GenericObjectPool#ensureMinIdle()}.
1694 */
1695 public void run() {
1696 try {
1697 evict();
1698 } catch(Exception e) {
1699 // ignored
1700 } catch(OutOfMemoryError oome) {
1701 // Log problem but give evictor thread a chance to continue in
1702 // case error is recoverable
1703 oome.printStackTrace(System.err);
1704 }
1705 try {
1706 ensureMinIdle();
1707 } catch(Exception e) {
1708 // ignored
1709 }
1710 }
1711 }
1712
1713 /**
1714 * A simple "struct" encapsulating the
1715 * configuration information for a {@link GenericObjectPool}.
1716 * @see GenericObjectPool#GenericObjectPool(org.apache.commons.pool.PoolableObjectFactory,
1717 * org.apache.commons.pool.impl.GenericObjectPool.Config)
1718 * @see GenericObjectPool#setConfig
1719 */
1720 public static class Config {
1721 /**
1722 * @see GenericObjectPool#setMaxIdle
1723 */
1724 public int maxIdle = GenericObjectPool.DEFAULT_MAX_IDLE;
1725 /**
1726 * @see GenericObjectPool#setMinIdle
1727 */
1728 public int minIdle = GenericObjectPool.DEFAULT_MIN_IDLE;
1729 /**
1730 * @see GenericObjectPool#setMaxActive
1731 */
1732 public int maxActive = GenericObjectPool.DEFAULT_MAX_ACTIVE;
1733 /**
1734 * @see GenericObjectPool#setMaxWait
1735 */
1736 public long maxWait = GenericObjectPool.DEFAULT_MAX_WAIT;
1737 /**
1738 * @see GenericObjectPool#setWhenExhaustedAction
1739 */
1740 public byte whenExhaustedAction = GenericObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
1741 /**
1742 * @see GenericObjectPool#setTestOnBorrow
1743 */
1744 public boolean testOnBorrow = GenericObjectPool.DEFAULT_TEST_ON_BORROW;
1745 /**
1746 * @see GenericObjectPool#setTestOnReturn
1747 */
1748 public boolean testOnReturn = GenericObjectPool.DEFAULT_TEST_ON_RETURN;
1749 /**
1750 * @see GenericObjectPool#setTestWhileIdle
1751 */
1752 public boolean testWhileIdle = GenericObjectPool.DEFAULT_TEST_WHILE_IDLE;
1753 /**
1754 * @see GenericObjectPool#setTimeBetweenEvictionRunsMillis
1755 */
1756 public long timeBetweenEvictionRunsMillis = GenericObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1757 /**
1758 * @see GenericObjectPool#setNumTestsPerEvictionRun
1759 */
1760 public int numTestsPerEvictionRun = GenericObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1761 /**
1762 * @see GenericObjectPool#setMinEvictableIdleTimeMillis
1763 */
1764 public long minEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1765 /**
1766 * @see GenericObjectPool#setSoftMinEvictableIdleTimeMillis
1767 */
1768 public long softMinEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1769 /**
1770 * @see GenericObjectPool#setLifo
1771 */
1772 public boolean lifo = GenericObjectPool.DEFAULT_LIFO;
1773
1774 }
1775
1776 /**
1777 * Latch used to control allocation order of objects to threads to ensure
1778 * fairness. That is, objects are allocated to threads in the order that
1779 * threads request objects.
1780 */
1781 private static final class Latch {
1782
1783 /** object timestamp pair allocated to this latch */
1784 private ObjectTimestampPair _pair;
1785
1786 /** Wheter or not this latch may create an object instance */
1787 private boolean _mayCreate = false;
1788
1789 /**
1790 * Returns ObjectTimestampPair allocated to this latch
1791 * @return ObjectTimestampPair allocated to this latch
1792 */
1793 private synchronized ObjectTimestampPair getPair() {
1794 return _pair;
1795 }
1796
1797 /**
1798 * Sets ObjectTimestampPair on this latch
1799 * @param pair ObjectTimestampPair allocated to this latch
1800 */
1801 private synchronized void setPair(ObjectTimestampPair pair) {
1802 _pair = pair;
1803 }
1804
1805 /**
1806 * Whether or not this latch may create an object instance
1807 * @return true if this latch has an instance creation permit
1808 */
1809 private synchronized boolean mayCreate() {
1810 return _mayCreate;
1811 }
1812
1813 /**
1814 * Sets the mayCreate property
1815 * @param mayCreate new value for mayCreate
1816 */
1817 private synchronized void setMayCreate(boolean mayCreate) {
1818 _mayCreate = mayCreate;
1819 }
1820
1821 /**
1822 * Reset the latch data. Used when an allocation fails and the latch
1823 * needs to be re-added to the queue.
1824 */
1825 private synchronized void reset() {
1826 _pair = null;
1827 _mayCreate = false;
1828 }
1829 }
1830
1831
1832 //--- private attributes ---------------------------------------
1833
1834 /**
1835 * The cap on the number of idle instances in the pool.
1836 * @see #setMaxIdle
1837 * @see #getMaxIdle
1838 */
1839 private int _maxIdle = DEFAULT_MAX_IDLE;
1840
1841 /**
1842 * The cap on the minimum number of idle instances in the pool.
1843 * @see #setMinIdle
1844 * @see #getMinIdle
1845 */
1846 private int _minIdle = DEFAULT_MIN_IDLE;
1847
1848 /**
1849 * The cap on the total number of active instances from the pool.
1850 * @see #setMaxActive
1851 * @see #getMaxActive
1852 */
1853 private int _maxActive = DEFAULT_MAX_ACTIVE;
1854
1855 /**
1856 * The maximum amount of time (in millis) the
1857 * {@link #borrowObject} method should block before throwing
1858 * an exception when the pool is exhausted and the
1859 * {@link #getWhenExhaustedAction "when exhausted" action} is
1860 * {@link #WHEN_EXHAUSTED_BLOCK}.
1861 *
1862 * When less than or equal to 0, the {@link #borrowObject} method
1863 * may block indefinitely.
1864 *
1865 * @see #setMaxWait
1866 * @see #getMaxWait
1867 * @see #WHEN_EXHAUSTED_BLOCK
1868 * @see #setWhenExhaustedAction
1869 * @see #getWhenExhaustedAction
1870 */
1871 private long _maxWait = DEFAULT_MAX_WAIT;
1872
1873 /**
1874 * The action to take when the {@link #borrowObject} method
1875 * is invoked when the pool is exhausted (the maximum number
1876 * of "active" objects has been reached).
1877 *
1878 * @see #WHEN_EXHAUSTED_BLOCK
1879 * @see #WHEN_EXHAUSTED_FAIL
1880 * @see #WHEN_EXHAUSTED_GROW
1881 * @see #DEFAULT_WHEN_EXHAUSTED_ACTION
1882 * @see #setWhenExhaustedAction
1883 * @see #getWhenExhaustedAction
1884 */
1885 private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
1886
1887 /**
1888 * When <tt>true</tt>, objects will be
1889 * {@link PoolableObjectFactory#validateObject validated}
1890 * before being returned by the {@link #borrowObject}
1891 * method. If the object fails to validate,
1892 * it will be dropped from the pool, and we will attempt
1893 * to borrow another.
1894 *
1895 * @see #setTestOnBorrow
1896 * @see #getTestOnBorrow
1897 */
1898 private volatile boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
1899
1900 /**
1901 * When <tt>true</tt>, objects will be
1902 * {@link PoolableObjectFactory#validateObject validated}
1903 * before being returned to the pool within the
1904 * {@link #returnObject}.
1905 *
1906 * @see #getTestOnReturn
1907 * @see #setTestOnReturn
1908 */
1909 private volatile boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
1910
1911 /**
1912 * When <tt>true</tt>, objects will be
1913 * {@link PoolableObjectFactory#validateObject validated}
1914 * by the idle object evictor (if any). If an object
1915 * fails to validate, it will be dropped from the pool.
1916 *
1917 * @see #setTestWhileIdle
1918 * @see #getTestWhileIdle
1919 * @see #getTimeBetweenEvictionRunsMillis
1920 * @see #setTimeBetweenEvictionRunsMillis
1921 */
1922 private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
1923
1924 /**
1925 * The number of milliseconds to sleep between runs of the
1926 * idle object evictor thread.
1927 * When non-positive, no idle object evictor thread will be
1928 * run.
1929 *
1930 * @see #setTimeBetweenEvictionRunsMillis
1931 * @see #getTimeBetweenEvictionRunsMillis
1932 */
1933 private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
1934
1935 /**
1936 * The max number of objects to examine during each run of the
1937 * idle object evictor thread (if any).
1938 * <p>
1939 * When a negative value is supplied, <tt>ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})</tt>
1940 * tests will be run. I.e., when the value is <i>-n</i>, roughly one <i>n</i>th of the
1941 * idle objects will be tested per run.
1942 *
1943 * @see #setNumTestsPerEvictionRun
1944 * @see #getNumTestsPerEvictionRun
1945 * @see #getTimeBetweenEvictionRunsMillis
1946 * @see #setTimeBetweenEvictionRunsMillis
1947 */
1948 private int _numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
1949
1950 /**
1951 * The minimum amount of time an object may sit idle in the pool
1952 * before it is eligible for eviction by the idle object evictor
1953 * (if any).
1954 * When non-positive, no objects will be evicted from the pool
1955 * due to idle time alone.
1956 *
1957 * @see #setMinEvictableIdleTimeMillis
1958 * @see #getMinEvictableIdleTimeMillis
1959 * @see #getTimeBetweenEvictionRunsMillis
1960 * @see #setTimeBetweenEvictionRunsMillis
1961 */
1962 private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1963
1964 /**
1965 * The minimum amount of time an object may sit idle in the pool
1966 * before it is eligible for eviction by the idle object evictor
1967 * (if any), with the extra condition that at least
1968 * "minIdle" amount of object remain in the pool.
1969 * When non-positive, no objects will be evicted from the pool
1970 * due to idle time alone.
1971 *
1972 * @see #setSoftMinEvictableIdleTimeMillis
1973 * @see #getSoftMinEvictableIdleTimeMillis
1974 */
1975 private long _softMinEvictableIdleTimeMillis = DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
1976
1977 /** Whether or not the pool behaves as a LIFO queue (last in first out) */
1978 private boolean _lifo = DEFAULT_LIFO;
1979
1980 /** My pool. */
1981 private CursorableLinkedList _pool = null;
1982
1983 /** Eviction cursor - keeps track of idle object evictor position */
1984 private CursorableLinkedList.Cursor _evictionCursor = null;
1985
1986 /** My {@link PoolableObjectFactory}. */
1987 private PoolableObjectFactory _factory = null;
1988
1989 /**
1990 * The number of objects {@link #borrowObject} borrowed
1991 * from the pool, but not yet returned.
1992 */
1993 private int _numActive = 0;
1994
1995 /**
1996 * My idle object eviction {@link TimerTask}, if any.
1997 */
1998 private Evictor _evictor = null;
1999
2000 /**
2001 * The number of objects subject to some form of internal processing
2002 * (usually creation or destruction) that should be included in the total
2003 * number of objects but are neither active nor idle.
2004 */
2005 private int _numInternalProcessing = 0;
2006
2007 /**
2008 * Used to track the order in which threads call {@link #borrowObject()} so
2009 * that objects can be allocated in the order in which the threads requested
2010 * them.
2011 */
2012 private LinkedList _allocationQueue = new LinkedList();
2013
2014 }