Do events within a transaction run synchronously?

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cseickel

Hello,

TLDR: Within a specific transaction, is it possible that multiple events will run concurrently, or are all events garanteed to run synchronously?

The longer version:

We are writing a behavior that will send node details to AWS Event Bridge on every edit for integration with another system. In order to handle the fact that multiple nodes may be edited within a transaction and each node may be altered several times due to folder rules and other behaviors, we are binding to EVERY_EVENT and keeping a collection of the edited nodes which is bound to the transaction with AlfrescoTransactionSupport.bindResource().

This was the example we are working off of:

https://angelborroy.wordpress.com/2015/05/22/alfresco-implementing-delete-behavior/

I originally assumed that Angel knows what he's talking about so it must be safe to use a plain old ArrayList and not worring about locking or race conditions, but I'd like to be 100% positive because it is hard to find these kind of errors in testing.

Thanks,

Chris

sufo

I am not sure if you are going the right way. Angel's example creates new transactions and does processing there, so it is asynchronous and can run in parallel. That code is executed after original modification was commited (starting from line 52 - afterCommit means what it says).

While under heavy load, we ran into issues and had to modify asynchronous processing little bit with counter (I am adding only a part of the code):

                if (transactionCounter == null) {
                    transactionCounter = 0;
                }
                // Bind listener to current transaction
                AlfrescoTransactionSupport.bindListener(new DocumentTransactionListener(transactionCounter));
                LOGGER.trace("Listener is binded to current nodeRef processing transaction. (transactionCounter = " + transactionCounter + ")");
                // Put resources to be used in transaction listener
                TransactionSupportUtil.bindResource(KEY_RELATED_NODE + transactionCounter.toString(), nodeRef);
                TransactionSupportUtil.bindResource(KEY_PROPS_BEFORE + transactionCounter.toString(), before);
                TransactionSupportUtil.bindResource(KEY_PROPS_AFTER + transactionCounter.toString(), after);
                TransactionSupportUtil.bindResource(KEY_DOCUMENT + transactionCounter.toString(), notInScanning);

                transactionCounter++;
                return null;
            }
        };
        AuthenticationUtil.runAs(raw, AuthenticationUtil.getAdminUserName());

    }

    // Listening "afterCommit" transaction event
    private class DocumentTransactionListener extends TransactionListenerAdapter implements TransactionListener {

        private final Integer id;

        public DocumentTransactionListener(final Integer id) {
            super();
            this.id = id;
        }

        @Override
        public void afterCommit() {
            final NodeRef nodeRef = TransactionSupportUtil.getResource(KEY_RELATED_NODE + id.toString());
            final Map<QName, Serializable> before = TransactionSupportUtil.getResource(KEY_PROPS_BEFORE + id.toString());
            final Map<QName, Serializable> after = TransactionSupportUtil.getResource(KEY_PROPS_AFTER + id.toString());
            final Boolean notInScanning = TransactionSupportUtil.getResource(KEY_DOCUMENT + id.toString());
            LOGGER.trace("DocumentTransactionListener afterCommit... NodeRef: " + nodeRef);