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/*
* SynchronizationManager.java
*
* Created on May 30, 2002, 8:43 AM
*/
package com.sun.jdo.api.persistence.support;
import java.util.ArrayList;
import java.util.List;
import java.util.Hashtable;
import javax.transaction.Synchronization;
/** This class allows for multiple instances to be called at transaction
* completion, which JDO does not currently provide. JDO only provides
* for a single instance to be registered. This service exploits
* the JDO capability by registering an instance of SynchronizationManager
* with JDO and then calling each instance registered with itself.
*
* @author Craig Russell
* @version 1.0
*/
public class SynchronizationManager implements Synchronization {
/** Creates new SynchronizationManager instance specifying the initial
* capacity of the list of Synchronization instances.
* @param initialCapacity the initial capacity of the List of Synchronization instances
*/
public SynchronizationManager(int initialCapacity) {
synchronizations = new ArrayList(initialCapacity);
}
/** Creates new SynchronizationManager instance with a default
* capacity of the List of Synchronization instances.
*/
public SynchronizationManager() {
this(defaultCapacity);
}
/** Register a new Synchronization with the current transaction.
* @param instance the instance to be registered
* @param pm the persistence manager which manages this transaction
*/
public static void registerSynchronization(Synchronization instance, PersistenceManager pm) {
SynchronizationManager synchronizationManager = getSynchronizationManager(pm);
synchronizationManager.registerSynchronization(instance);
}
/** Specify the default capacity of the list of Synchronizations.
* @param capacity the default capacity of the List of Synchronizations
*/
public static void setDefaultCapacity(int capacity) {
defaultCapacity = capacity;
}
/** The default capacity of the List of Synchronizations.
*/
protected static int defaultCapacity = 100;
/** The list of instances to synchronize. Duplicate registrations will
* result in the instance being called multiple times. Since we cannot
* depend on the caller implementing hashCode and equals, we cannot use
* a Set implementaion.
*/
protected final List synchronizations;
/** Creates new SynchronizationManager instance and registers it with
* the persistence manager.
* @param pm the persistence manager managing this transaction
*/
protected SynchronizationManager(PersistenceManager pm) {
this();
Transaction tx = pm.currentTransaction();
tx.setSynchronization((Synchronization)this);
}
/** Get the synchronization manager already registered with this persistence manager.
* If the synchronization instance is not of the proper class, then replace it with
* a new instance of the synchronization manager, and register the previous synchronization
* with the newly created synchronization manager.
* @param pm the persistence manager
* @return the synchronization manager
*/
protected static SynchronizationManager getSynchronizationManager(PersistenceManager pm) {
Transaction tx = pm.currentTransaction();
Synchronization oldsync = tx.getSynchronization();
if (oldsync instanceof SynchronizationManager) {
// This is the one we want.
return (SynchronizationManager) oldsync;
} else {
// We need a new one. The constructor automatically registers it
// with the persistence manager.
SynchronizationManager newsync = new SynchronizationManager(pm);
if (oldsync != null) {
// There is an existing Synchronization to register with the new one
newsync.registerSynchronization(oldsync);
}
return newsync;
}
}
/** This method will be called during transaction completion. Resource
* access is allowed.
* This method in turn calls each registered instance beforeCompletion
* method.
*/
public void beforeCompletion() {
int size = synchronizations.size();
for (int i = 0; i < size; ++i) {
Synchronization instance = (Synchronization) synchronizations.get(i);
instance.beforeCompletion();
}
}
/** This method will be called during transaction completion. No resource
* access is allowed.
* This method in turn calls each registered instance afterCompletion
* method. After this method completes,
* instances must register again in the new transaction, but
* the synchronization manager remains bound to the persistence manager
* transaction instance.
* @param status the completion status of the transaction
*/
public void afterCompletion(int status) {
int size = synchronizations.size();
StringBuffer sb = null;
for (int i = 0; i < size; ++i) {
Synchronization instance = (Synchronization) synchronizations.get(i);
try {
instance.afterCompletion(status);
} catch (Exception e) {
if (sb == null) {
sb = new StringBuffer();
}
sb.append(e.getMessage()).append('\n'); // NOI18N
}
}
synchronizations.clear();
if (sb != null) {
throw new JDOUserException(sb.toString());
}
}
/** Register an instance with this synchronization manager.
* Note that this is not thread-safe. If multiple threads call this method
* at the same time, the synchronizations List might become corrupt.
* The correct way to fix this is to ask the PersistenceManager for the
* Multithreaded flag and perform a synchronized add if the flag is true.
* We currently do not have the Multithreaded flag implemented.
* @param instance the instance to be registered
*/
protected void registerSynchronization(Synchronization instance) {
synchronizations.add(instance);
}
}
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