wireprotoserver: document and improve the httplib workaround This workaround dates all the way back to a42d27bc809d in 2008. The code is esoteric enough to warrant an inline explanation. So I've added one. At the time the code was written, the only wire protocol command that accepted an HTTP request body was "unbundle." In the years since, we've grown the ability to accept command arguments via HTTP POST requests. So, the code has been changed to apply the httplib workaround to all HTTP POST requests. While staring at this code, I realized that the HTTP response body in case of error is always the same. And, it appears to mimic the behavior of a failed call to the "unbundle" command. Since we can hit this code path on theoretically any protocol request (since self.check_perm accepts custom auth checking functions which may raise), I'm having a hard time believing that clients react well to an "unbundle" response payload on any wire protocol command. I wouldn't be surprised if our test coverage for this feature only covers HTTP POST calls to "unbundle." In other words, the experimental support for sending arguments via HTTP POST request bodies may result in badness on the client. Something to investigate another time perhaps... Differential Revision: https://phab.mercurial-scm.org/D2064

wireprotoserver: move error response handling out of hgweb The exception handler for ErrorResponse has more to do with the wire protocol than the generic HTTP server. Move the code so it lives alongside other wire protocol code. Differential Revision: https://phab.mercurial-scm.org/D2021

hgweb: move call to protocol handler outside of try..except The protocol handler doesn't raise ErrorResponse. So it doesn't need to be in this `try..except ErrorResponse` block. Differential Revision: https://phab.mercurial-scm.org/D2020

wireprotoserver: move protocol parsing and dispatch out of hgweb Previously, hgweb_mod had code for detecting if the request was for the wire protocol. It would then (eventually) call wireprotoserver.callhttp() to dispatch the request handling. Detection of wire protocol requests is not trivial. There's currently a big gotcha in the handling of the "cmd" request parameter, for example. Furthermore, in the near future we will have a second HTTP protocol handler. Its mechanism for calling commands will be a bit different. And we don't want the low-level logic for detecting protocol commands to live in hgweb. We establish a new function in wireprotoserver for detecting an HTTP protocol request and for giving the caller an easy-to-use mechanism for dispatching requests to it. Some wire protocol specific functionality still lives in hgweb. This will be addressed in subsequent commits. Differential Revision: https://phab.mercurial-scm.org/D2019

largefiles: register wire protocol commands with modern APIs The wireproto.wireprotocommand decorator is the preferred mechanism for registering wire protocol commands. In addition, wireproto.commands is no longer a 2-tuple and use of that 2-tuple API should be considered deprecated. This commit ports largefiles to use wireproto.wireprotocommand() and ports to the "commandentry" API. As part of this, the definition of the "lheads" wire protocol command is moved to the proper stanza. We stop short of actually using wireprotocommand as a decorator in order to minimize churn. We should ideally move wire protocol commands to the registrar mechanism. But that's for another changeset. Differential Revision: https://phab.mercurial-scm.org/D2018

wireproto: function for testing if wire protocol command is available Currently, we perform simple membership testing for whether a wire command is available. In the future, not all wire protocol commands will be available on all transports. For example, a legacy transport may not support newer commands. In preparation of this, teach the protocol handlers to call into a function to determine if a wire protocol command is available. That function currently does membership testing like before, so behavior should be identical. In the case of the HTTP server, behavior is a bit wonkier. "cmd" is used by both the wire protocol and hgweb. We do want the protocol handler to handle requests for all commands that look like wire protocol commands, even if they aren't available. Otherwise, the fallback to hgweb would only confuse automated clients and make it easier for hgweb to accidentally implement a "cmd" that is identical to wire protocol commands (since they aren't centrally registered). Differential Revision: https://phab.mercurial-scm.org/D1999