diff mercurial/localrepo.py @ 37630:e1b32dc4646c

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

--- a/mercurial/localrepo.py	Fri Apr 13 10:23:05 2018 -0700
+++ b/mercurial/localrepo.py	Fri Apr 13 10:51:23 2018 -0700
@@ -11,6 +11,7 @@
 import hashlib
 import os
 import random
+import sys
 import time
 import weakref
 
@@ -167,6 +168,49 @@
             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 @@
 
     # Begin of peer interface.
 
+    def commandexecutor(self):
+        return localcommandexecutor(self)
+
     def iterbatch(self):
         return localiterbatcher(self)