D2982: wireproto: separate commands tables for version 1 and 2 commands

[indygreg (Gregory Szorc)]

indygreg created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  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.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2982

AFFECTED FILES
  hgext/largefiles/uisetup.py
  mercurial/wireproto.py
  mercurial/wireprotoserver.py
  tests/test-wireproto.py

CHANGE DETAILS

diff --git a/tests/test-wireproto.py b/tests/test-wireproto.py
--- a/tests/test-wireproto.py
+++ b/tests/test-wireproto.py
@@ -13,6 +13,8 @@
 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 @@
     def checkperm(self, perm):
         pass
 
+wireprototypes.TRANSPORTS['dummyproto'] = {
+    'transport': 'dummy',
+    'version': 1,
+}
+
 class clientpeer(wireproto.wirepeer):
     def __init__(self, serverrepo, ui):
         self.serverrepo = serverrepo
diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -335,7 +335,7 @@
     # 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 @@
 
     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 @@
     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 @@
 
         # 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':
diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -502,7 +502,11 @@
 
 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 @@
 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 @@
     """
     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 @@
                                      permission)
 
     def register(func):
-        commands[name] = commandentry(func, args=args, transports=transports,
-                                      permission=permission)
+        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
 
diff --git a/hgext/largefiles/uisetup.py b/hgext/largefiles/uisetup.py
--- a/hgext/largefiles/uisetup.py
+++ b/hgext/largefiles/uisetup.py
@@ -175,6 +175,7 @@
 
     # ... 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)
 



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Cc: mercurial-devel