wireproto: implement command executor interface for version 1 peers

Now that we've defined our new interface for issuing commands,
let's implement it.

We add the interface to the base peer interface. This means all
peer types must implement it.

The only peer types that we have are the local peer in localrepo
and a shared wire peer for version 1 of the wire protocol.

The local peer implementation is pretty straightforward. We
don't do anything fancy and just return a resolved future with
the result of a method call. This is similar to what
localiterbatcher does.

The wire protocol version 1 implementation is a bit more complicated
and is a more robust implementation.

The wire executor queues commands by default. And because the new
executor interface always allows multiple commands but not all version
1 commands are @batchable, it has to check that the requested commands
are batchable if multiple commands are being requested.

The wire executor currently only supports executing a single command.
This is for simplicity reasons. Support for multiple commands will
be added in a separate commit.

To prove the new interface works, a call to the "known" command
during discovery has been updated to use the new API.

It's worth noting that both implementations require a method having
the command name to exist on the peer. There is at least one caller
in core that don't have a method calls peer._call() directly. We
may need to shore up the requirements later...

Differential Revision: https://phab.mercurial-scm.org/D3268

mercurial/localrepo.py

@@ -11,6 +11,7 b' import errno'
 import hashlib
 import os
 import random
+import sys
 import time
 import weakref
 
@@ -167,6 +168,49 b' class localiterbatcher(wireprotov1peer.i'
             resref.set(getattr(self.local, name)(*args, **opts))
             yield resref.value
 
[e-mail](repository.ipeercommandexecutor)
+class localcommandexecutor(object):
+    def __init__(self, peer):
+        self._peer = peer
+        self._sent = False
+        self._closed = False
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exctype, excvalue, exctb):
+        self.close()
+
+    def callcommand(self, command, args):
+        if self._sent:
+            raise error.ProgrammingError('callcommand() cannot be used after '
+                                         'sendcommands()')
+
+        if self._closed:
+            raise error.ProgrammingError('callcommand() cannot be used after '
+                                         'close()')
+
+        # We don't need to support anything fancy. Just call the named
+        # method on the peer and return a resolved future.
+        fn = getattr(self._peer, pycompat.sysstr(command))
+
+        f = pycompat.futures.Future()
+
+        try:
+            result = fn(**args)
+        except Exception:
+            f.set_exception_info(*sys.exc_info()[1:])
+        else:
+            f.set_result(result)
+
+        return f
+
+    def sendcommands(self):
+        self._sent = True
+
+    def close(self):
+        self._closed = True
+
 class localpeer(repository.peer):
     '''peer for a local repo; reflects only the most recent API'''
 
@@ -286,6 +330,9 b' class localpeer(repository.peer):'
 
     # Begin of peer interface.
 
+    def commandexecutor(self):
+        return localcommandexecutor(self)
+
     def iterbatch(self):
         return localiterbatcher(self)
 

mercurial/repository.py

@@ -278,7 +278,8 b' class ipeerrequests(zi.Interface):'
         being issued.
         """
 
-class ipeerbase(ipeerconnection, ipeercapabilities, ipeercommands):
+class ipeerbase(ipeerconnection, ipeercapabilities, ipeercommands,
+                ipeerrequests):
     """Unified interface for peer repositories.
 
     All peer instances must conform to this interface.

mercurial/setdiscovery.py

@@ -228,7 +228,12 b' def findcommonheads(ui, local, remote,'
                  % (roundtrips, len(undecided), len(sample)))
         # indices between sample and externalized version must match
         sample = list(sample)
-        yesno = remote.known(dag.externalizeall(sample))
+
+        with remote.commandexecutor() as e:
+            yesno = e.callcommand('known', {
+                'nodes': dag.externalizeall(sample),
+            }).result()
+
         full = True
 
         if sample:

mercurial/wireprotov1peer.py

@@ -8,12 +8,15 b''
 from __future__ import absolute_import
 
 import hashlib
+import sys
 
 from .i18n import _
 from .node import (
     bin,
 )
-
+from .thirdparty.zope import (
+    interface as zi,
+)
 from . import (
     bundle2,
     changegroup as changegroupmod,
@@ -177,6 +180,93 b' def encodebatchcmds(req):'
 
     return ';'.join(cmds)
 
[e-mail](repository.ipeercommandexecutor)
+class peerexecutor(object):
+    def __init__(self, peer):
+        self._peer = peer
+        self._sent = False
+        self._closed = False
+        self._calls = []
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exctype, excvalee, exctb):
+        self.close()
+
+    def callcommand(self, command, args):
+        if self._sent:
+            raise error.ProgrammingError('callcommand() cannot be used '
+                                         'after commands are sent')
+
+        if self._closed:
+            raise error.ProgrammingError('callcommand() cannot be used '
+                                         'after close()')
+
+        # Commands are dispatched through methods on the peer.
+        fn = getattr(self._peer, pycompat.sysstr(command), None)
+
+        if not fn:
+            raise error.ProgrammingError(
+                'cannot call command %s: method of same name not available '
+                'on peer' % command)
+
+        # Commands are either batchable or they aren't. If a command
+        # isn't batchable, we send it immediately because the executor
+        # can no longer accept new commands after a non-batchable command.
+        # If a command is batchable, we queue it for later.
+
+        if getattr(fn, 'batchable', False):
+            pass
+        else:
+            if self._calls:
+                raise error.ProgrammingError(
+                    '%s is not batchable and cannot be called on a command '
+                    'executor along with other commands' % command)
+
+        # We don't support batching yet. So resolve it immediately.
+        f = pycompat.futures.Future()
+        self._calls.append((command, args, fn, f))
+        self.sendcommands()
+        return f
+
+    def sendcommands(self):
+        if self._sent:
+            return
+
+        if not self._calls:
+            return
+
+        self._sent = True
+
+        calls = self._calls
+        # Mainly to destroy references to futures.
+        self._calls = None
+
+        if len(calls) == 1:
+            command, args, fn, f = calls[0]
+
+            # Future was cancelled. Ignore it.
+            if not f.set_running_or_notify_cancel():
+                return
+
+            try:
+                result = fn(**pycompat.strkwargs(args))
+            except Exception:
+                f.set_exception_info(*sys.exc_info()[1:])
+            else:
+                f.set_result(result)
+
+            return
+
+        raise error.ProgrammingError('support for multiple commands not '
+                                     'yet implemented')
+
+    def close(self):
+        self.sendcommands()
+
+        self._closed = True
+
 class wirepeer(repository.legacypeer):
     """Client-side interface for communicating with a peer repository.
 
@@ -185,6 +275,9 b' class wirepeer(repository.legacypeer):'
     See also httppeer.py and sshpeer.py for protocol-specific
     implementations of this interface.
     """
+    def commandexecutor(self):
+        return peerexecutor(self)
+
     # Begin of ipeercommands interface.
 
     def iterbatch(self):

tests/test-check-interfaces.py

@@ -23,6 +23,7 b' from mercurial import ('
     vfs as vfsmod,
     wireprotoserver,
     wireprototypes,
+    wireprotov1peer,
     wireprotov2server,
 )
 
@@ -102,6 +103,14 b' def main():'
                          localrepo.localpeer)
     checkzobject(localrepo.localpeer(dummyrepo()))
 
+    ziverify.verifyClass(repository.ipeercommandexecutor,
+                         localrepo.localcommandexecutor)
+    checkzobject(localrepo.localcommandexecutor(None))
+
+    ziverify.verifyClass(repository.ipeercommandexecutor,
+                         wireprotov1peer.peerexecutor)
+    checkzobject(wireprotov1peer.peerexecutor(None))
+
     ziverify.verifyClass(repository.ipeerbaselegacycommands,
                          sshpeer.sshv1peer)
     checkzobject(sshpeer.sshv1peer(ui, 'ssh://localhost/foo', None, dummypipe(),