httppeer: implement command executor for version 2 peer Now that we have a new API for issuing commands which is compatible with wire protocol version 2, we can start using it with wire protocol version 2. This commit replaces our hacky implementation of _call() with something a bit more robust based on the new command executor interface. We now have proper support for issuing multiple commands per HTTP request. Each HTTP request maintains its own client reactor. The implementation is similar to the one in the legacy wire protocol. We use a ThreadPoolExecutor for spinning up a thread to read the HTTP response in the background. This allows responses to resolve in any order. While not implemented on the server yet, a client could use concurrent.futures.as_completed() with a collection of futures and handle responses as they arrive from the server. The return value from issued commands is still a simple list of raw or decoded CBOR data. This is still super hacky. We will want a rich data type for representing command responses. But at least this commit gets us one step closer to a proper peer implementation. Differential Revision: https://phab.mercurial-scm.org/D3297

repository: remove ipeercommands from ipeerbase AFAICT all callers in core have moved to the commandexecutor interface for invoking wire protocol commands. Or at least they aren't using the named methods on ipeercommands to invoke them. This means we can drop ipeercommands from the ipeerbase interface. As far as interface based programming goes, it is now illegal to call an ipeercommands method for issuing wire protocol commands. However, the methods are still there, so they will still work. At some point we will want to break that API... Differential Revision: https://phab.mercurial-scm.org/D3318

wireproto: properly call clonebundles command We should not be using _call() to make wire protocol calls because it isn't part of the peer API. But clonebundles wasn't part of the supported commands in the peer API! So this commit defines that command in the commands interface, implements it, and teaches the one caller in core to call it using the command executor interface. Differential Revision: https://phab.mercurial-scm.org/D3317

exchange: use command executor for getbundle The code consuming the bundle has been moved to inside the context manager, as that is supposed to be part of the API. (Although it doesn't matter for version 1 peers.) Differential Revision: https://phab.mercurial-scm.org/D3316

exchange: use command executor for pushkey Differential Revision: https://phab.mercurial-scm.org/D3315

wireproto: use command executor for unbundle This also required unifying the name of the argument because the new API always passes arguments by keyword. I decided to change implementations to "bundle" instead of the interface to "cg" because "bundle" is more appropriate in a modern world. Differential Revision: https://phab.mercurial-scm.org/D3314

debugcommands: perform handshake when obtaining httpv2 peer If we obtain an httpv2peer directly, the instance doesn't have an API descriptor and therefore doesn't know about the remote's commands, feature support, etc. This doesn't matter now. But when we implement the peer so it consults the API descriptor as part of sending commands, it will. So we change the logic for obtaining an http version 2 peer to go through makepeer() so the peer will perform the handshake and pass the API descriptor to the httpv2peer instance. Tests changed because we now perform a ?cmd=capabilities when obtaining version 2 peers. The Content-Length header is globbed because compression info will lack zstandard for pure builds. Differential Revision: https://phab.mercurial-scm.org/D3296

wireproto: rename HTTPV2 so it less like HTTP/2 Per review suggestion on D3230 from Augie. Differential Revision: https://phab.mercurial-scm.org/D3295

bundlerepo: use command executor for wire protocol commands Differential Revision: https://phab.mercurial-scm.org/D3294

bundlerepo: rename "other" to "peer" Differential Revision: https://phab.mercurial-scm.org/D3293