<cfscript>

	param name="url.pollID" type="string";

	// Lists in Redis provide both blocking and non-blocking operations. In this case,
	// we're going to use BLPOP (Blocking Left-Pop) to block-and-hang the parent page
	// request for several seconds (3) while waiting for the given list to be populated.
	// If no list-item can be popped in the given timeout, the result will be null.
	results = application.redisGateway.withRedis(
		( redis ) => {

			var blockTimeout = 3; // Time to block in seconds.
			var lists = [ "poll:#url.pollID#" ];

			var popResult = redis.blpop( blockTimeout, lists );

			// The result of the BLPOP operation is 2-tuple where the first index is the
			// name of the key (since we can block on multiple keys at the same time);
			// and, the second index is the value of the list item that we popped.
			if ( ! isNull( popResult ) ) {

				return( popResult[ 2 ] );

			}

		}
	);

	// If there was no result, the job is still processing. For the sake of simplicity,
	// let's just return a 404 Not Found in this case.
	if ( isNull( results ) ) {

		header
			statuscode = 404
			statustext = "Not Found"
		;
		exit;

	}

	content
		type = "application/x-json"
		variable = charsetDecode( serializeJson( results ), "utf-8" )
	;

</cfscript>