[CAMEL-17075] DatasonnetBuilder (and SimpleBuilder) does initialization in evaluate() which can cause issues under load

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.11.2
• Fix Version/s: 3.13.0
• Component/s: camel-core
• Estimated Complexity: Unknown
• Assignee: Claus Ibsen
• Reporter: Henrik Karlsson
• Created: 13/Oct/21 11:43
• Updated: 14/Oct/21 08:07
• Resolved: 14/Oct/21 08:06

Description

When running a simple HelloWorld app that uses datasonnet to produce the response with a high amount of requests we got a lot of exception:
java.lang.IllegalStateException: Datasonnet expression not initialized

Looking into DatasonnetBuilder I see that some initialisation is made inside evaluate():

    @Override
    public <T> T evaluate(Exchange exchange, Class<T> type) {
        if (expression == null) {
            if (datasonnet == null) {
                init(exchange.getContext());
            }
            if (resultType != null) {
                Object[] properties = new Object[3];
                properties[0] = resultType;
                properties[1] = bodyMediaType;
                properties[2] = outputMediaType;
                expression = datasonnet.createExpression(text, properties);
            } else {
                expression = datasonnet.createExpression(text);
            }
            expression.init(exchange.getContext());
        }
        return expression.evaluate(exchange, type);
    }

As expression is set before expression.init() is called another thread could bypass the initialisation of expression and call expression.evalutate() before expression.init() has finished. Moving this initialisation to the init method of DatasonnetBuilder would solve this problem. 
The same problem goes for SimpleBuilder which was used as a template for implementation DatasonnetBuilder.

Issue Links

• relates to: CAMEL-17079 camel-core - Avoid using SimpleBuilder to make simple expressions similar to others
• links to: GitHub Pull Request #6267