wireproto: separate commands tables for version 1 and 2 commands

We can't easily reuse existing command handlers for version 2
commands because the response types will be different. e.g. many
commands return nodes encoded as hex. Our new wire protocol is
binary safe, so we'll wish to encode nodes as binary.

We /could/ teach each command handler to look at the protocol
handler and change behavior based on the version in use. However,
this would make logic a bit unwieldy over time and would make
it harder to design a unified protocol handler interface. I think
it's better to create a clean break between version 1 and version 2
of commands on the server.

What I imagine happening is we will have separate @wireprotocommand
functions for each protocol generation. Those functions will parse the
request, dispatch to a common function to process it, then generate
the response in its own, transport-specific manner.

This commit establishes a separate table for tracking version 1
commands from version 2 commands. The HTTP server pieces have been
updated to use this new table.

Most commands are marked as both version 1 and version 2, so there is
little practical impact to this change.

A side-effect of this change is we now rely on transport registration
in wireprototypes.TRANSPORTS and certain properties of the protocol
interface. So a test had to be updated to conform.

Differential Revision: https://phab.mercurial-scm.org/D2982

hgext/largefiles/uisetup.py

@@ -175,6 +175,7 b' def uisetup(ui):'
 
     # ... and wrap some existing ones
     wireproto.commands['heads'].func = proto.heads
+    # TODO also wrap wireproto.commandsv2 once heads is implemented there.
 
     extensions.wrapfunction(webcommands, 'decodepath', overrides.decodepath)
 

mercurial/wireproto.py

@@ -502,7 +502,11 b' def getdispatchrepo(repo, proto, command'
 
 def dispatch(repo, proto, command):
     repo = getdispatchrepo(repo, proto, command)
-    func, spec = commands[command]
+
+    transportversion = wireprototypes.TRANSPORTS[proto.name]['version']
+    commandtable = commandsv2 if transportversion == 2 else commands
+    func, spec = commandtable[command]
+
     args = proto.getargs(spec)
     return func(repo, proto, *args)
 
@@ -679,8 +683,12 b" POLICY_ALL = 'all'"
 POLICY_V1_ONLY = 'v1-only'
 POLICY_V2_ONLY = 'v2-only'
 
+# For version 1 transports.
 commands = commanddict()
 
+# For version 2 transports.
+commandsv2 = commanddict()
+
 def wireprotocommand(name, args='', transportpolicy=POLICY_ALL,
                      permission='push'):
     """Decorator to declare a wire protocol command.
@@ -702,12 +710,15 b" def wireprotocommand(name, args='', tran"
     """
     if transportpolicy == POLICY_ALL:
         transports = set(wireprototypes.TRANSPORTS)
+        transportversions = {1, 2}
     elif transportpolicy == POLICY_V1_ONLY:
         transports = {k for k, v in wireprototypes.TRANSPORTS.items()
                       if v['version'] == 1}
+        transportversions = {1}
     elif transportpolicy == POLICY_V2_ONLY:
         transports = {k for k, v in wireprototypes.TRANSPORTS.items()
                       if v['version'] == 2}
+        transportversions = {2}
     else:
         raise error.ProgrammingError('invalid transport policy value: %s' %
                                      transportpolicy)
@@ -724,8 +735,21 b" def wireprotocommand(name, args='', tran"
                                      permission)
 
     def register(func):
-        commands[name] = commandentry(func, args=args, transports=transports,
+        if 1 in transportversions:
+            if name in commands:
+                raise error.ProgrammingError('%s command already registered '
+                                             'for version 1' % name)
+            commands[name] = commandentry(func, args=args,
+                                          transports=transports,
                                       permission=permission)
+        if 2 in transportversions:
+            if name in commandsv2:
+                raise error.ProgrammingError('%s command already registered '
+                                             'for version 2' % name)
+            commandsv2[name] = commandentry(func, args=args,
+                                            transports=transports,
+                                            permission=permission)
+
         return func
     return register
 

mercurial/wireprotoserver.py

@@ -335,7 +335,7 b' def _handlehttpv2request(rctx, req, res,'
     # extension.
     extracommands = {'multirequest'}
 
-    if command not in wireproto.commands and command not in extracommands:
+    if command not in wireproto.commandsv2 and command not in extracommands:
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('unknown wire protocol command: %s\n') % command)
@@ -346,7 +346,7 b' def _handlehttpv2request(rctx, req, res,'
 
     proto = httpv2protocolhandler(req, ui)
 
-    if (not wireproto.commands.commandavailable(command, proto)
+    if (not wireproto.commandsv2.commandavailable(command, proto)
         and command not in extracommands):
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
@@ -502,7 +502,7 b' def _httpv2runcommand(ui, repo, req, res'
     proto = httpv2protocolhandler(req, ui, args=command['args'])
 
     if reqcommand == b'multirequest':
-        if not wireproto.commands.commandavailable(command['command'], proto):
+        if not wireproto.commandsv2.commandavailable(command['command'], proto):
             # TODO proper error mechanism
             res.status = b'200 OK'
             res.headers[b'Content-Type'] = b'text/plain'
@@ -512,7 +512,7 b' def _httpv2runcommand(ui, repo, req, res'
 
         # TODO don't use assert here, since it may be elided by -O.
         assert authedperm in (b'ro', b'rw')
-        wirecommand = wireproto.commands[command['command']]
+        wirecommand = wireproto.commandsv2[command['command']]
         assert wirecommand.permission in ('push', 'pull')
 
         if authedperm == b'ro' and wirecommand.permission != 'pull':

tests/test-wireproto.py

@@ -13,6 +13,8 b' stringio = util.stringio'
 class proto(object):
     def __init__(self, args):
         self.args = args
+        self.name = 'dummyproto'
+
     def getargs(self, spec):
         args = self.args
         args.setdefault(b'*', {})
@@ -22,6 +24,11 b' class proto(object):'
     def checkperm(self, perm):
         pass
 
+wireprototypes.TRANSPORTS['dummyproto'] = {
+    'transport': 'dummy',
+    'version': 1,
+}
+
 class clientpeer(wireproto.wirepeer):
     def __init__(self, serverrepo, ui):
         self.serverrepo = serverrepo