StructuralChangeTransactionAggregator.java

//
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 * the License. You may obtain a copy of the License at
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 *
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 * for the specific language governing rights and limitations under the
 * License.
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 * The Original Code is part of dcm4che, an implementation of DICOM(TM) in
 * Java(TM), hosted at https://github.com/gunterze/dcm4che.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 2011
 * the Initial Developer. All Rights Reserved.
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 * See @authors listed below
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package org.dcm4chee.archive.sc.impl;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.transaction.RollbackException;
import javax.transaction.Status;
import javax.transaction.Synchronization;
import javax.transaction.SystemException;
import javax.transaction.Transaction;
import javax.transaction.TransactionSynchronizationRegistry;

import org.dcm4chee.archive.sc.StructuralChangeContext;
import org.dcm4chee.archive.sc.StructuralChangeRejectedException;
import org.dcm4chee.util.TransactionSynchronization;

/**
 * Aggregates structural changes that happen within a transaction.
 * 
 * @author Alexander Hoermandinger <alexander.hoermandinger@agfa.com>
 */
@ApplicationScoped
public class StructuralChangeTransactionAggregator {
    private static final String ON_SC_COMMIT_RUNNER_TX_RESOURCE = OnStructuralChangesCommitRunner.class.getName();
    
    @Inject
    private TransactionSynchronization txSnychronization;
    
    @Inject
    private StructuralChangeHookExecutor scChangeHookExecutor;
    
    /**
     * Aggregates the result state of a QC operation to the current QC workflow.
     * @param qcEvent Result state of QC operation
     */
    public void aggregate(StructuralChangeContext changeContext) {
        StructuralChangeContainerImpl changeContainer = initOrGetChangeContainer();
        if (changeContainer != null) {
            changeContainer.addContext(changeContext);
        }
    }
    
    private StructuralChangeContainerImpl initOrGetChangeContainer() {
        try {
            Transaction tx = txSnychronization.getTransactionManager().getTransaction();
            if (tx == null) {
                return null;
            }
            
            TransactionSynchronizationRegistry txSyncRegistry = txSnychronization.getSynchronizationRegistry();

            OnStructuralChangesCommitRunner  onStructuralChangesCommitRunner  = (OnStructuralChangesCommitRunner)txSyncRegistry.getResource(ON_SC_COMMIT_RUNNER_TX_RESOURCE);
            if (onStructuralChangesCommitRunner == null) {
                onStructuralChangesCommitRunner = new OnStructuralChangesCommitRunner();
                tx.registerSynchronization(onStructuralChangesCommitRunner);
                txSyncRegistry.putResource(ON_SC_COMMIT_RUNNER_TX_RESOURCE, onStructuralChangesCommitRunner);
            }
            return onStructuralChangesCommitRunner.getStructuralChangeContainer();
        } catch (SystemException | IllegalStateException e) {
            throw new RuntimeException("Could not register transaction synchronizer for aggregating structural changes within transaction");
        } catch (RollbackException e) {
            return null;
        } 
    }
    
    /*
     * Transaction synchronization hook that executes logic in the before-commit and after-commit
     * phases of a transaction with structural changes
     */
    private class OnStructuralChangesCommitRunner implements Synchronization {
        private StructuralChangeContainerImpl changeContainer = new StructuralChangeContainerImpl();

        private StructuralChangeContainerImpl getStructuralChangeContainer() {
            return changeContainer;
        }
        
        /*
         * Method ONLY CALLED for ACTIVE (not-rolled-back) transactions!
         * 
         * Reason for setting the context classloader: the beforeCompletion() might be called
         * when committing a transaction started / associated with another deployment (EAR). 
         * CDI (Weld) would use the context classloader from the other EAR to resolve scChangeHookExecutor 
         * => fails with exception.
         */
        @Override
        public void beforeCompletion() {
            if (changeContainer != null) {
                ClassLoader origCtxClassLoader = Thread.currentThread().getContextClassLoader();
                try {
                    Thread.currentThread().setContextClassLoader(StructuralChangeTransactionAggregator.class.getClassLoader());
                    if (!scChangeHookExecutor.executeBeforeCommitStructuralChangeHooks(changeContainer)) {
                        // let transaction fail
                        throw new StructuralChangeRejectedException();
                    }
                } finally {
                    Thread.currentThread().setContextClassLoader(origCtxClassLoader);
                }
            }
        }
        
        @Override
        public void afterCompletion(int status) {
            if (changeContainer != null) {
                ClassLoader origCtxClassLoader = Thread.currentThread().getContextClassLoader();
                try {
                    Thread.currentThread().setContextClassLoader(StructuralChangeTransactionAggregator.class.getClassLoader());
                    if(status == Status.STATUS_COMMITTED) {
                        scChangeHookExecutor.asyncExecuteAfterCommitStructuralChangeHooks(changeContainer);
                    }
                } finally {
                    changeContainer = null;
                    Thread.currentThread().setContextClassLoader(origCtxClassLoader);
                }
            }
        }
       
    }

}