Implement MrHorse.parallel, switch Async to Items

[devinivy]

Here's MrHorse.parallel, currently sans documentation. See tests for usage for now. Happy to answer any questions about this! Builds on top of work done in #15. Related discussion: #11.

Short example config from tests,

server.route({
    method : 'GET',
    path   : '/parallel-ok',
    handler: function (request, reply) {

        reply({
            handler: 'handler'
        });
    },
    config : {
        plugins: {
            policies: [ MrHorse.parallel('postHandler', 'postHandlerAnother') ]
        }
    }
});

[devinivy]

Ah, didn't take into account shrinkwrapping. CI should be happy as of the shrinkwrap update in devinivy@a3158e3. Also memoized the function that determines an apply point from a list of policy names.

[devinivy]

Added syntactic sugar. Example in the first comment of this PR can be rewritten alternately as,

server.route({
    method : 'GET',
    path   : '/parallel-ok',
    handler: function (request, reply) {

        reply({
            handler: 'handler'
        });
    },
    config : {
        plugins: {
            policies: [
                [ 'postHandler', 'postHandlerAnother' ]
            ]
        }
    }
});

[devinivy]

Added some docs.

[mark-bradshaw]

Thanks Devin. I don't have availability tonight to look over and comment.
I'll take a look tomorrow.

On Tue, Jul 7, 2015 at 2:12 PM devin ivy notifications@github.com wrote:

Added some docs.

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#17 (comment).

[mark-bradshaw]

What about changing "by default the first listed policy with such an error will be given precedence." to "the error response from the left most policy will be returned to the browser."

[mark-bradshaw]

Also, we need to be clear that parallel only accepts strings, not functions, since the last param can be a callback. Right?

[mark-bradshaw]

So I plowed through the PR. Basically, it looks good. I had some comments and questions as I went. I think it might be worth taking another look once the dust settles and see if some refactoring might make things simpler, and I definitely agree that we need to be caching the list of policies to run instead of recalculating on each request. Another thing I'd like to see (another PR) is to split out some of the helper functions into a separate file to cut down on line count.

If you could go through the comments and either answer questions or adjust what seems to make sense I'd appreciate it.

[devinivy]

Thanks for taking such a detailed look! Let's get this right, so that we can feel good about the next release. I'll try to resolve these line notes tomorrow.

[devinivy]

I made the suggested changes, and tried to clarify some wording. I also added an example to the docs of using currying with function-policies, since I think that may be a desirable use-case.

[mark-bradshaw]

Looks good. Merging.