hgweb: support using new response object for web commands We have a "requestcontext" type for holding state for the current request. Why we pass in the wsgirequest and templater instance to @webcommand functions, I don't know. I like the idea of standardizing on using "requestcontext" for passing all state to @webcommand functions because that scales well without API changes every time you want to pass a new piece of data. So, we add our new request and response instances to "requestcontext" so @webcommand functions can access them. We also teach our command dispatcher to recognize a new calling convention. Instead of returning content from the @webcommand function, we return our response object. This signals that this response object is to be used for sending output. The keyword extension was wrapping various @webcommand and assuming the output was iterable, so we had to teach it about the new calling convention. To prove everything works, we convert the "filelog" @webcommand to use the new convention. The new calling convention is a bit wonky. I intend to improve this once all commands are ported to use the new response object. Differential Revision: https://phab.mercurial-scm.org/D2786

hgweb: inline caching() and port to modern mechanisms We only had one consumer of this simple function. While it could be a generic function, let's not over abstract the code. As part of inlining, we port it off wsgirequest, fix some Python 3 issues, and set a response header on our new response object so it is ready once we start using it to send responses. Differential Revision: https://phab.mercurial-scm.org/D2785

hgweb: expose repo name on parsedrequest I'm not a fan of doing this because I want to find a better solution to the REPO_NAME hack. But this change gets us a few steps closer to eliminating use of wsgirequest. We can worry about fixing REPO_NAME once wsgirequest is gone. Differential Revision: https://phab.mercurial-scm.org/D2784

hgweb: expose URL scheme and REMOTE_* attributes These are consulted by the HTTP wire protocol handler by reading from the env dict. Let's expose them as attributes instead. With the wire protocol handler updates to use the new attributes, we no longer have any consumers of the legacy wsgirequest type in the wire protocol code (outside of a proxied call to the permissions checker). So, we remove most references to it. Differential Revision: https://phab.mercurial-scm.org/D2783

hgweb: remove wsgirequest.form (API) Now that everything is ported to consume from parsedrequest.qsparams, we no longer have a need for wsgirequest.form. Let's remove all references to it. .. api:: The WSGI request object no longer exposes a ``form`` attribute containing parsed query string data. Use the ``qsparams`` attribute instead. Differential Revision: https://phab.mercurial-scm.org/D2782

hgweb: perform all parameter lookup via qsparams I think I managed to update all call sites using wsgirequest.form to use parsedrequest.qsparams. Since behavior of qsparams is to retrieve last value, behavior will change if a parameter was specified multiple times. But I think this is acceptable. I'm not a fan of the `req.req.qsparams` pattern. And some of the modified code could be written better. But I was aiming for a straight port with this change. Cleanup can come later. Differential Revision: https://phab.mercurial-scm.org/D2781

hgweb: set variables in qsparams We currently mutate wsgireq.form in a few places. Since it is independent from req.qsparams, we will need to make changes on req.qsparams as well before consumers can use qsparams. So let's do that. Eventually, we'll delete wsgireq.form and all references to it. Differential Revision: https://phab.mercurial-scm.org/D2780

hgweb: use our new request object for "style" parameter The "style" parameter is kind of wonky because it is explicitly set and has lookups in random locations. Let's port it to qsparams first because it isn't straightforward. There is subtle change in behavior. But I don't think it is worth calling out in a BC. Our multidict's __getitem__ returns the last set value for a key, not the first. So if the query string set a variable multiple times, before we would get the first value and now we would get the last value. It makes no sense to specify these things multiple times. And I think last write wins is more sensible than first write wins. Differential Revision: https://phab.mercurial-scm.org/D2779

hgweb: use a multidict for holding query string parameters My intention with refactoring the WSGI code was to make it easier to read. I initially wanted to vendor and use WebOb, because it seems to be a pretty reasonable abstraction layer for WSGI. However, it isn't using relative imports and I didn't want to deal with the hassle of patching it. But that doesn't mean we can't use good ideas from WebOb. WebOb has a "multidict" data structure for holding parsed query string and POST form data. It quacks like a dict but allows you to store multiple values for each key. It offers mechanisms to return just one value, all values, or return 1 value asserting that only 1 value is set. I quite like its API. This commit implements a read-only "multidict" in the spirit of WebOb's multidict. We replace the query string attributes of our parsed request with an instance of it. Differential Revision: https://phab.mercurial-scm.org/D2776

hgweb: create dedicated type for WSGI responses We have refactored the request side of WSGI processing into a dedicated type. Now let's do the same thing for the response side. We invent a ``wsgiresponse`` type. It takes an instance of a request (for consulation) and the WSGI application's "start_response" handler. The type basically allows setting the HTTP status line, response headers, and the response body. The WSGI application calls sendresponse() to start sending output. Output is emitted as a generator to be fed through the WSGI application. According to PEP 3333, this is the preferred way for output to be transmitted. (Our legacy ``wsgirequest`` exposed a write() to send data. We do not wish to support this API because it isn't recommended by PEP 3333.) The wire protocol code has been ported to use the new API. Differential Revision: https://phab.mercurial-scm.org/D2775