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package org.apache.camel.bam.processor; |
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import org.apache.camel.Exchange; |
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import org.apache.camel.Expression; |
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import org.apache.camel.Processor; |
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import org.apache.camel.RuntimeCamelException; |
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import org.apache.commons.logging.Log; |
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import org.apache.commons.logging.LogFactory; |
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import org.springframework.dao.DataIntegrityViolationException; |
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import org.springframework.orm.jpa.JpaSystemException; |
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import org.springframework.transaction.TransactionStatus; |
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import org.springframework.transaction.support.TransactionCallback; |
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import org.springframework.transaction.support.TransactionTemplate; |
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import javax.persistence.EntityExistsException; |
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import java.lang.reflect.ParameterizedType; |
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import java.lang.reflect.Type; |
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public abstract class BamProcessorSupport<T> implements Processor { |
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private static final transient Log LOG = LogFactory.getLog(BamProcessorSupport.class); |
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private Class<T> entityType; |
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private Expression<Exchange> correlationKeyExpression; |
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private TransactionTemplate transactionTemplate; |
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private int maximumRetries = 30; |
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public int getMaximumRetries() { |
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return maximumRetries; |
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} |
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public void setMaximumRetries(int maximumRetries) { |
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this.maximumRetries = maximumRetries; |
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} |
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protected BamProcessorSupport(TransactionTemplate transactionTemplate, Expression<Exchange> correlationKeyExpression) { |
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this.transactionTemplate = transactionTemplate; |
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this.correlationKeyExpression = correlationKeyExpression; |
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Type type = getClass().getGenericSuperclass(); |
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if (type instanceof ParameterizedType) { |
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ParameterizedType parameterizedType = (ParameterizedType) type; |
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Type[] arguments = parameterizedType.getActualTypeArguments(); |
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if (arguments.length > 0) { |
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Type argumentType = arguments[0]; |
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if (argumentType instanceof Class) { |
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this.entityType = (Class<T>) argumentType; |
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} |
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} |
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} |
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if (entityType == null) { |
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throw new IllegalArgumentException("Could not infer the entity type!"); |
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} |
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} |
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protected BamProcessorSupport(TransactionTemplate transactionTemplate, Expression<Exchange> correlationKeyExpression, Class<T> entitytype) { |
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this.transactionTemplate = transactionTemplate; |
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this.entityType = entitytype; |
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this.correlationKeyExpression = correlationKeyExpression; |
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} |
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public void process(final Exchange exchange) { |
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Object entity = null; |
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for (int i = 0; entity == null && i < maximumRetries; i++) { |
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if (i > 0) { |
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LOG.info("Retry attempt due to duplicate row: " + i); |
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} |
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entity = transactionTemplate.execute(new TransactionCallback() { |
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public Object doInTransaction(TransactionStatus status) { |
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try { |
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Object key = getCorrelationKey(exchange); |
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T entity = loadEntity(exchange, key); |
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if (LOG.isDebugEnabled()) { |
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LOG.debug("Correlation key: " + key + " with entity: " + entity); |
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} |
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processEntity(exchange, entity); |
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return entity; |
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} |
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catch (JpaSystemException e) { |
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if (LOG.isDebugEnabled()) { |
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LOG.debug("Likely exception is due to duplicate row in concurrent setting: " + e, e); |
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} |
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LOG.info("Attempt to insert duplicate row due to concurrency issue, so retrying: " + e); |
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return retryDueToDuplicate(status); |
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} |
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catch (DataIntegrityViolationException e) { |
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Throwable throwable = e.getCause(); |
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if (throwable instanceof EntityExistsException) { |
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LOG.info("Attempt to insert duplicate row due to concurrency issue, so retrying: " + throwable); |
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return retryDueToDuplicate(status); |
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} |
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return onError(status, throwable); |
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} |
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catch (Throwable e) { |
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return onError(status, e); |
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} |
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} |
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}); |
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} |
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} |
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public Expression<Exchange> getCorrelationKeyExpression() { |
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return correlationKeyExpression; |
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} |
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public Class<T> getEntityType() { |
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return entityType; |
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} |
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protected abstract void processEntity(Exchange exchange, T entity) throws Exception; |
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protected abstract T loadEntity(Exchange exchange, Object key); |
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protected Object getCorrelationKey(Exchange exchange) throws NoCorrelationKeyException { |
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Object value = correlationKeyExpression.evaluate(exchange); |
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if (value == null) { |
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throw new NoCorrelationKeyException(this, exchange); |
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} |
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return value; |
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} |
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protected Object retryDueToDuplicate(TransactionStatus status) { |
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status.setRollbackOnly(); |
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return null; |
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} |
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protected Object onError(TransactionStatus status, Throwable e) { |
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status.setRollbackOnly(); |
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LOG.error("Caught: " + e, e); |
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throw new RuntimeCamelException(e); |
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} |
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} |