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Java Source Code / Java Documentation » J2EE » spring framework 2.0.6 » org.springframework.transaction.support 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 2002-2007 the original author or authors.
003:         *
004:         * Licensed under the Apache License, Version 2.0 (the "License");
005:         * you may not use this file except in compliance with the License.
006:         * You may obtain a copy of the License at
007:         *
008:         *      http://www.apache.org/licenses/LICENSE-2.0
009:         *
010:         * Unless required by applicable law or agreed to in writing, software
011:         * distributed under the License is distributed on an "AS IS" BASIS,
012:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013:         * See the License for the specific language governing permissions and
014:         * limitations under the License.
015:         */
016:
017:        package org.springframework.transaction.support;
018:
019:        import java.util.ArrayList;
020:        import java.util.Collections;
021:        import java.util.Comparator;
022:        import java.util.HashMap;
023:        import java.util.LinkedList;
024:        import java.util.List;
025:        import java.util.Map;
026:
027:        import org.apache.commons.logging.Log;
028:        import org.apache.commons.logging.LogFactory;
029:
030:        import org.springframework.core.OrderComparator;
031:        import org.springframework.util.Assert;
032:
033:        /**
034:         * Central helper that manages resources and transaction synchronizations per thread.
035:         * To be used by resource management code but not by typical application code.
036:         *
037:         * <p>Supports one resource per key without overwriting, that is, a resource needs
038:         * to be removed before a new one can be set for the same key.
039:         * Supports a list of transaction synchronizations if synchronization is active.
040:         *
041:         * <p>Resource management code should check for thread-bound resources, e.g. JDBC
042:         * Connections or Hibernate Sessions, via <code>getResource</code>. Such code is
043:         * normally not supposed to bind resources to threads, as this is the responsibility
044:         * of transaction managers. A further option is to lazily bind on first use if
045:         * transaction synchronization is active, for performing transactions that span
046:         * an arbitrary number of resources.
047:         *
048:         * <p>Transaction synchronization must be activated and deactivated by a transaction
049:         * manager via {@link #initSynchronization()} and {@link #clearSynchronization()}.
050:         * This is automatically supported by {@link AbstractPlatformTransactionManager},
051:         * and thus by all standard Spring transaction managers, such as
052:         * {@link org.springframework.transaction.jta.JtaTransactionManager} and
053:         * {@link org.springframework.jdbc.datasource.DataSourceTransactionManager}.
054:         *
055:         * <p>Resource management code should only register synchronizations when this
056:         * manager is active, which can be checked via {@link #isSynchronizationActive};
057:         * it should perform immediate resource cleanup else. If transaction synchronization
058:         * isn't active, there is either no current transaction, or the transaction manager
059:         * doesn't support transaction synchronization.
060:         *
061:         * <p>Synchronization is for example used to always return the same resources
062:         * within a JTA transaction, e.g. a JDBC Connection or a Hibernate Session for
063:         * any given DataSource or SessionFactory, respectively.
064:         *
065:         * @author Juergen Hoeller
066:         * @since 02.06.2003
067:         * @see #isSynchronizationActive
068:         * @see #registerSynchronization
069:         * @see TransactionSynchronization
070:         * @see AbstractPlatformTransactionManager#setTransactionSynchronization
071:         * @see org.springframework.transaction.jta.JtaTransactionManager
072:         * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
073:         * @see org.springframework.jdbc.datasource.DataSourceUtils#getConnection
074:         */
075:        public abstract class TransactionSynchronizationManager {
076:
077:            private static final Log logger = LogFactory
078:                    .getLog(TransactionSynchronizationManager.class);
079:
080:            private static final ThreadLocal resources = new ThreadLocal();
081:
082:            private static final ThreadLocal synchronizations = new ThreadLocal();
083:
084:            private static final Comparator synchronizationComparator = new OrderComparator();
085:
086:            private static final ThreadLocal currentTransactionName = new ThreadLocal();
087:
088:            private static final ThreadLocal currentTransactionReadOnly = new ThreadLocal();
089:
090:            private static final ThreadLocal currentTransactionIsolationLevel = new ThreadLocal();
091:
092:            private static final ThreadLocal actualTransactionActive = new ThreadLocal();
093:
094:            //-------------------------------------------------------------------------
095:            // Management of transaction-associated resource handles
096:            //-------------------------------------------------------------------------
097:
098:            /**
099:             * Return all resources that are bound to the current thread.
100:             * <p>Mainly for debugging purposes. Resource managers should always invoke
101:             * <code>hasResource</code> for a specific resource key that they are interested in.
102:             * @return a Map with resource keys (usually the resource factory) and resource
103:             * values (usually the active resource object), or an empty Map if there are
104:             * currently no resources bound
105:             * @see #hasResource
106:             */
107:            public static Map getResourceMap() {
108:                Map map = (Map) resources.get();
109:                return (map != null ? Collections.unmodifiableMap(map)
110:                        : Collections.EMPTY_MAP);
111:            }
112:
113:            /**
114:             * Check if there is a resource for the given key bound to the current thread.
115:             * @param key the key to check (usually the resource factory)
116:             * @return if there is a value bound to the current thread
117:             * @see ResourceTransactionManager#getResourceFactory() 
118:             */
119:            public static boolean hasResource(Object key) {
120:                Assert.notNull(key, "Key must not be null");
121:                Map map = (Map) resources.get();
122:                return (map != null && map.containsKey(key));
123:            }
124:
125:            /**
126:             * Retrieve a resource for the given key that is bound to the current thread.
127:             * @param key the key to check (usually the resource factory)
128:             * @return a value bound to the current thread (usually the active
129:             * resource object), or <code>null</code> if none
130:             * @see ResourceTransactionManager#getResourceFactory()
131:             */
132:            public static Object getResource(Object key) {
133:                Assert.notNull(key, "Key must not be null");
134:                Map map = (Map) resources.get();
135:                if (map == null) {
136:                    return null;
137:                }
138:                Object value = map.get(key);
139:                if (value != null && logger.isDebugEnabled()) {
140:                    logger.debug("Retrieved value [" + value + "] for key ["
141:                            + key + "] bound to thread ["
142:                            + Thread.currentThread().getName() + "]");
143:                }
144:                return value;
145:            }
146:
147:            /**
148:             * Bind the given resource for the given key to the current thread.
149:             * @param key the key to bind the value to (usually the resource factory)
150:             * @param value the value to bind (usually the active resource object)
151:             * @throws IllegalStateException if there is already a value bound to the thread
152:             * @see ResourceTransactionManager#getResourceFactory()
153:             */
154:            public static void bindResource(Object key, Object value)
155:                    throws IllegalStateException {
156:                Assert.notNull(key, "Key must not be null");
157:                Assert.notNull(value, "Value must not be null");
158:                Map map = (Map) resources.get();
159:                // set ThreadLocal Map if none found
160:                if (map == null) {
161:                    map = new HashMap();
162:                    resources.set(map);
163:                }
164:                if (map.containsKey(key)) {
165:                    throw new IllegalStateException("Already value ["
166:                            + map.get(key) + "] for key [" + key
167:                            + "] bound to thread ["
168:                            + Thread.currentThread().getName() + "]");
169:                }
170:                map.put(key, value);
171:                if (logger.isDebugEnabled()) {
172:                    logger.debug("Bound value [" + value + "] for key [" + key
173:                            + "] to thread ["
174:                            + Thread.currentThread().getName() + "]");
175:                }
176:            }
177:
178:            /**
179:             * Unbind a resource for the given key from the current thread.
180:             * @param key the key to unbind (usually the resource factory)
181:             * @return the previously bound value (usually the active resource object)
182:             * @throws IllegalStateException if there is no value bound to the thread
183:             * @see ResourceTransactionManager#getResourceFactory()
184:             */
185:            public static Object unbindResource(Object key)
186:                    throws IllegalStateException {
187:                Assert.notNull(key, "Key must not be null");
188:                Map map = (Map) resources.get();
189:                if (map == null || !map.containsKey(key)) {
190:                    throw new IllegalStateException("No value for key [" + key
191:                            + "] bound to thread ["
192:                            + Thread.currentThread().getName() + "]");
193:                }
194:                Object value = map.remove(key);
195:                // remove entire ThreadLocal if empty
196:                if (map.isEmpty()) {
197:                    resources.set(null);
198:                }
199:                if (logger.isDebugEnabled()) {
200:                    logger.debug("Removed value [" + value + "] for key ["
201:                            + key + "] from thread ["
202:                            + Thread.currentThread().getName() + "]");
203:                }
204:                return value;
205:            }
206:
207:            //-------------------------------------------------------------------------
208:            // Management of transaction synchronizations
209:            //-------------------------------------------------------------------------
210:
211:            /**
212:             * Return if transaction synchronization is active for the current thread.
213:             * Can be called before register to avoid unnecessary instance creation.
214:             * @see #registerSynchronization
215:             */
216:            public static boolean isSynchronizationActive() {
217:                return (synchronizations.get() != null);
218:            }
219:
220:            /**
221:             * Activate transaction synchronization for the current thread.
222:             * Called by a transaction manager on transaction begin.
223:             * @throws IllegalStateException if synchronization is already active
224:             */
225:            public static void initSynchronization()
226:                    throws IllegalStateException {
227:                if (isSynchronizationActive()) {
228:                    throw new IllegalStateException(
229:                            "Cannot activate transaction synchronization - already active");
230:                }
231:                logger.debug("Initializing transaction synchronization");
232:                synchronizations.set(new LinkedList());
233:            }
234:
235:            /**
236:             * Register a new transaction synchronization for the current thread.
237:             * Typically called by resource management code.
238:             * <p>Note that synchronizations can implement the
239:             * {@link org.springframework.core.Ordered} interface.
240:             * They will be executed in an order according to their order value (if any).
241:             * @param synchronization the synchronization object to register
242:             * @throws IllegalStateException if transaction synchronization is not active
243:             * @see org.springframework.core.Ordered
244:             */
245:            public static void registerSynchronization(
246:                    TransactionSynchronization synchronization)
247:                    throws IllegalStateException {
248:
249:                Assert.notNull(synchronization,
250:                        "TransactionSynchronization must not be null");
251:                if (!isSynchronizationActive()) {
252:                    throw new IllegalStateException(
253:                            "Transaction synchronization is not active");
254:                }
255:                List synchs = (List) synchronizations.get();
256:                synchs.add(synchronization);
257:            }
258:
259:            /**
260:             * Return an unmodifiable snapshot list of all registered synchronizations
261:             * for the current thread.
262:             * @return unmodifiable List of TransactionSynchronization instances
263:             * @throws IllegalStateException if synchronization is not active
264:             * @see TransactionSynchronization
265:             */
266:            public static List getSynchronizations()
267:                    throws IllegalStateException {
268:                if (!isSynchronizationActive()) {
269:                    throw new IllegalStateException(
270:                            "Transaction synchronization is not active");
271:                }
272:                List synchs = (List) synchronizations.get();
273:                // Sort lazily here, not in registerSynchronization.
274:                Collections.sort(synchs, synchronizationComparator);
275:                // Return unmodifiable snapshot, to avoid ConcurrentModificationExceptions
276:                // while iterating and invoking synchronization callbacks that in turn
277:                // might register further synchronizations.
278:                return Collections.unmodifiableList(new ArrayList(synchs));
279:            }
280:
281:            /**
282:             * Deactivate transaction synchronization for the current thread.
283:             * Called by the transaction manager on transaction cleanup.
284:             * @throws IllegalStateException if synchronization is not active
285:             */
286:            public static void clearSynchronization()
287:                    throws IllegalStateException {
288:                if (!isSynchronizationActive()) {
289:                    throw new IllegalStateException(
290:                            "Cannot deactivate transaction synchronization - not active");
291:                }
292:                logger.debug("Clearing transaction synchronization");
293:                synchronizations.set(null);
294:            }
295:
296:            //-------------------------------------------------------------------------
297:            // Exposure of transaction characteristics
298:            //-------------------------------------------------------------------------
299:
300:            /**
301:             * Expose the name of the current transaction, if any.
302:             * Called by the transaction manager on transaction begin and on cleanup.
303:             * @param name the name of the transaction, or <code>null</code> to reset it
304:             * @see org.springframework.transaction.TransactionDefinition#getName()
305:             */
306:            public static void setCurrentTransactionName(String name) {
307:                currentTransactionName.set(name);
308:            }
309:
310:            /**
311:             * Return the name of the current transaction, or <code>null</code> if none set.
312:             * To be called by resource management code for optimizations per use case,
313:             * for example to optimize fetch strategies for specific named transactions.
314:             * @see org.springframework.transaction.TransactionDefinition#getName()
315:             */
316:            public static String getCurrentTransactionName() {
317:                return (String) currentTransactionName.get();
318:            }
319:
320:            /**
321:             * Expose a read-only flag for the current transaction.
322:             * Called by the transaction manager on transaction begin and on cleanup.
323:             * @param readOnly <code>true</code> to mark the current transaction
324:             * as read-only; <code>false</code> to reset such a read-only marker
325:             * @see org.springframework.transaction.TransactionDefinition#isReadOnly()
326:             */
327:            public static void setCurrentTransactionReadOnly(boolean readOnly) {
328:                currentTransactionReadOnly.set(readOnly ? Boolean.TRUE : null);
329:            }
330:
331:            /**
332:             * Return whether the current transaction is marked as read-only.
333:             * To be called by resource management code when preparing a newly
334:             * created resource (for example, a Hibernate Session).
335:             * <p>Note that transaction synchronizations receive the read-only flag
336:             * as argument for the <code>beforeCommit</code> callback, to be able
337:             * to suppress change detection on commit. The present method is meant
338:             * to be used for earlier read-only checks, for example to set the
339:             * flush mode of a Hibernate Session to "FlushMode.NEVER" upfront.
340:             * @see org.springframework.transaction.TransactionDefinition#isReadOnly()
341:             * @see TransactionSynchronization#beforeCommit(boolean)
342:             * @see org.hibernate.Session#flush
343:             * @see org.hibernate.Session#setFlushMode
344:             * @see org.hibernate.FlushMode#NEVER
345:             */
346:            public static boolean isCurrentTransactionReadOnly() {
347:                return (currentTransactionReadOnly.get() != null);
348:            }
349:
350:            /**
351:             * Expose an isolation level for the current transaction.
352:             * Called by the transaction manager on transaction begin and on cleanup.
353:             * @param isolationLevel the isolation level to expose, according to the
354:             * JDBC Connection constants (equivalent to the corresponding Spring
355:             * TransactionDefinition constants), or <code>null</code> to reset it
356:             * @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED
357:             * @see java.sql.Connection#TRANSACTION_READ_COMMITTED
358:             * @see java.sql.Connection#TRANSACTION_REPEATABLE_READ
359:             * @see java.sql.Connection#TRANSACTION_SERIALIZABLE
360:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_UNCOMMITTED
361:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_COMMITTED
362:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_REPEATABLE_READ
363:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_SERIALIZABLE
364:             * @see org.springframework.transaction.TransactionDefinition#getIsolationLevel()
365:             */
366:            public static void setCurrentTransactionIsolationLevel(
367:                    Integer isolationLevel) {
368:                currentTransactionIsolationLevel.set(isolationLevel);
369:            }
370:
371:            /**
372:             * Return the isolation level for the current transaction, if any.
373:             * To be called by resource management code when preparing a newly
374:             * created resource (for example, a JDBC Connection).
375:             * @return the currently exposed isolation level, according to the
376:             * JDBC Connection constants (equivalent to the corresponding Spring
377:             * TransactionDefinition constants), or <code>null</code> if none
378:             * @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED
379:             * @see java.sql.Connection#TRANSACTION_READ_COMMITTED
380:             * @see java.sql.Connection#TRANSACTION_REPEATABLE_READ
381:             * @see java.sql.Connection#TRANSACTION_SERIALIZABLE
382:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_UNCOMMITTED
383:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_COMMITTED
384:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_REPEATABLE_READ
385:             * @see org.springframework.transaction.TransactionDefinition#ISOLATION_SERIALIZABLE
386:             * @see org.springframework.transaction.TransactionDefinition#getIsolationLevel()
387:             */
388:            public static Integer getCurrentTransactionIsolationLevel() {
389:                return (Integer) currentTransactionIsolationLevel.get();
390:            }
391:
392:            /**
393:             * Expose whether there currently is an actual transaction active.
394:             * Called by the transaction manager on transaction begin and on cleanup.
395:             * @param active <code>true</code> to mark the current thread as being associated
396:             * with an actual transaction; <code>false</code> to reset that marker
397:             */
398:            public static void setActualTransactionActive(boolean active) {
399:                actualTransactionActive.set(active ? Boolean.TRUE : null);
400:            }
401:
402:            /**
403:             * Return whether there currently is an actual transaction active.
404:             * This indicates whether the current thread is associated with an actual
405:             * transaction rather than just with active transaction synchronization.
406:             * <p>To be called by resource management code that wants to discriminate
407:             * between active transaction synchronization (with or without backing
408:             * resource transaction; also on PROPAGATION_SUPPORTS) and an actual
409:             * transaction being active (with backing resource transaction;
410:             * on PROPAGATION_REQUIRES, PROPAGATION_REQUIRES_NEW, etc).
411:             * @see #isSynchronizationActive()
412:             */
413:            public static boolean isActualTransactionActive() {
414:                return (actualTransactionActive.get() != null);
415:            }
416:
417:            /**
418:             * Clear the entire transaction synchronization state for the current thread:
419:             * registered synchronizations as well as the various transaction characteristics.
420:             * @see #clearSynchronization()
421:             * @see #setCurrentTransactionName
422:             * @see #setCurrentTransactionReadOnly
423:             * @see #setCurrentTransactionIsolationLevel
424:             * @see #setActualTransactionActive
425:             */
426:            public static void clear() {
427:                clearSynchronization();
428:                setCurrentTransactionName(null);
429:                setCurrentTransactionReadOnly(false);
430:                setCurrentTransactionIsolationLevel(null);
431:                setActualTransactionActive(false);
432:            }
433:
434:        }
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