Deglobal #59
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Deglobal #59
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It's still used in HttpErrorHelper, but I'll need to nix that one, too.
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| Context.prototype.protocol = function () { | ||
| return config.presented_url_proto() || this._request.protocol; |
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looks like a leftover reference to the _request property
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Stashing the "current" request and response as globals in
RequestHelperandResponseHelperis not a good idea. It works... as long a single presenter is never serving more than one request at once, in which case you'll very quickly start writing output to the wrong response object. I believe this is the cause of the sporadic "headers already sent" bug that we've been seeing this month (and now that I have some basic log aggregation going, I'm seeing the occasional 500 be served in production).Essentially, this is a consequence of the way that node.js does asynchronous I/O with its event loop. Even though node is single-process and single-threaded, it achieves the throughput it does by interleaving other work while one request's handler is blocked waiting for upstream I/O to complete. This means that, while request A is waiting for a response from the content service, a request B that arrives before that response does will begin to be handled, and trash
ResponseHelper._responsefor request A before request A has a chance to be completed.I rigged up a simple demonstration of this happening by assigning IDs to each response object and firing a bunch of curl requests. Notice how every request tries to complete by writing to response 5, not its actual response object!
In its place, I've replaced the global service state with a
Contextobject that knows the current request and response and can mediate some of the mechanics that were being handled by theRequestHelperandResponseHelpermethods, as well as theHttpErrorHelper.