wireprotov2: decode responses to their expected types

Callers of established wire protocol commands expect the
response from that command to be decoded into a data structure.
It's not very useful if callers get back a stream of bytes and
don't know how they should be interpreted - especially since that
stream of bytes varies by wire protocol and even the transport
within that protocol version.

This commit establishes decoding functions for various command
responses so callers of those commands get the response type
they expect.

In theory, this should make the version 2 HTTP peer usable for
various operations. But I haven't tested to confirm.

Differential Revision: https://phab.mercurial-scm.org/D3381

mercurial/wireprotov2peer.py

@@ -12,6 +12,7 b' from .thirdparty import ('
     cbor,
 )
 from . import (
+    encoding,
     error,
     util,
     wireprotoframing,
@@ -127,7 +128,13 b' class clienthandler(object):'
                 response.cbor = True
 
             if meta['eos']:
-                self._futures[frame.requestid].set_result(response)
+                # If the command has a decoder, resolve the future to the
+                # decoded value. Otherwise resolve to the rich response object.
+                decoder = COMMAND_DECODERS.get(response.command)
+
+                result = decoder(response) if decoder else response
+
+                self._futures[frame.requestid].set_result(result)
 
                 del self._requests[frame.requestid]
                 del self._futures[frame.requestid]
@@ -135,3 +142,38 b' class clienthandler(object):'
         else:
             raise error.ProgrammingError(
                 'unhandled action from clientreactor: %s' % action)
+
+def decodebranchmap(resp):
+    # Response should be a single CBOR map of branch name to array of nodes.
+    bm = next(resp.cborobjects())
+
+    return {encoding.tolocal(k): v for k, v in bm.items()}
+
+def decodeheads(resp):
+    # Array of node bytestrings.
+    return next(resp.cborobjects())
+
+def decodeknown(resp):
+    # Bytestring where each byte is a 0 or 1.
+    raw = next(resp.cborobjects())
+
+    return [True if c == '1' else False for c in raw]
+
+def decodelistkeys(resp):
+    # Map with bytestring keys and values.
+    return next(resp.cborobjects())
+
+def decodelookup(resp):
+    return next(resp.cborobjects())
+
+def decodepushkey(resp):
+    return next(resp.cborobjects())
+
+COMMAND_DECODERS = {
+    'branchmap': decodebranchmap,
+    'heads': decodeheads,
+    'known': decodeknown,
+    'listkeys': decodelistkeys,
+    'lookup': decodelookup,
+    'pushkey': decodepushkey,
+}

tests/test-wireproto-command-branchmap.t

@@ -67,6 +67,6 b' No arguments returns something reasonabl'
   received frame(size=112; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [{b'branch1': [b'\xb5\xfa\xac\xdf\xd2c7h\xcb1R3l\xc0\x953\x81&f\x88'], b'branch2': [b'"Aa\xc7X\x9a\xa4\x8f\xa8:H\xfe\xff^\x95\xb5j\xe3\'\xfc'], b'default': [b'&\x80Z\xba\x1e`\n\x82\xe96a\x14\x9f#\x13\x86j"\x1a{', b'\xbe\x0e\xf7<\x17\xad\xe3\xfc\x89\xdcAp\x1e\xb9\xfc:\x91\xb5\x82\x82']}]
+  response: {b'branch1': [b'\xb5\xfa\xac\xdf\xd2c7h\xcb1R3l\xc0\x953\x81&f\x88'], b'branch2': [b'"Aa\xc7X\x9a\xa4\x8f\xa8:H\xfe\xff^\x95\xb5j\xe3\'\xfc'], b'default': [b'&\x80Z\xba\x1e`\n\x82\xe96a\x14\x9f#\x13\x86j"\x1a{', b'\xbe\x0e\xf7<\x17\xad\xe3\xfc\x89\xdcAp\x1e\xb9\xfc:\x91\xb5\x82\x82']}
 
   $ cat error.log

tests/test-wireproto-command-heads.t

@@ -58,7 +58,7 b' All non-secret heads returned by default'
   received frame(size=64; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [[b'\x1dok\x91\xd4J\xab\xa6\xd5\xe5\x80\xbc0\xa9\x94\x850\xdb\xe0\x0b', b'\xaeI.6\xb0\xc83\x9f\xfa\xf3(\xd0\x0b\x85\xb4R]\xe1\x16^', b')Dm-\xc5A\x9c_\x97Dz\x8b\xc0b\xe4\xcc2\x8b\xf2A']]
+  response: [b'\x1dok\x91\xd4J\xab\xa6\xd5\xe5\x80\xbc0\xa9\x94\x850\xdb\xe0\x0b', b'\xaeI.6\xb0\xc83\x9f\xfa\xf3(\xd0\x0b\x85\xb4R]\xe1\x16^', b')Dm-\xc5A\x9c_\x97Dz\x8b\xc0b\xe4\xcc2\x8b\xf2A']
 
 Requesting just the public heads works
 
@@ -91,6 +91,6 b' Requesting just the public heads works'
   received frame(size=22; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [[b'x\xd2\xdc\xa46\xb2\xf5\xb1\x88\xac&~)\xb8\x1e\x07&m8\xfc']]
+  response: [b'x\xd2\xdc\xa46\xb2\xf5\xb1\x88\xac&~)\xb8\x1e\x07&m8\xfc']
 
   $ cat error.log

tests/test-wireproto-command-known.t

@@ -50,7 +50,7 b' No arguments returns something reasonabl'
   received frame(size=1; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [b'']
+  response: []
 
 Single known node works
 
@@ -83,7 +83,7 b' Single known node works'
   received frame(size=2; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [b'1']
+  response: [True]
 
 Multiple nodes works
 
@@ -116,6 +116,6 b' Multiple nodes works'
   received frame(size=4; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [b'101']
+  response: [True, False, True]
 
   $ cat error.log

tests/test-wireproto-command-listkeys.t

@@ -54,7 +54,7 b' Request for namespaces works'
   received frame(size=32; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [{b'bookmarks': b'', b'namespaces': b'', b'phases': b''}]
+  response: {b'bookmarks': b'', b'namespaces': b'', b'phases': b''}
 
 Request for phases works
 
@@ -87,7 +87,7 b' Request for phases works'
   received frame(size=61; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [{b'be0ef73c17ade3fc89dc41701eb9fc3a91b58282': b'1', b'publishing': b'True'}]
+  response: {b'be0ef73c17ade3fc89dc41701eb9fc3a91b58282': b'1', b'publishing': b'True'}
 
 Request for bookmarks works
 
@@ -120,6 +120,6 b' Request for bookmarks works'
   received frame(size=45; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [{b'@': b'26805aba1e600a82e93661149f2313866a221a7b'}]
+  response: {b'@': b'26805aba1e600a82e93661149f2313866a221a7b'}
 
   $ cat error.log

tests/test-wireproto-command-lookup.t

@@ -50,6 +50,6 b' lookup for known node works'
   received frame(size=*; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor) (glob)
   s>     0\r\n
   s>     \r\n
-  response: [b'Bk\xad\xa5\xc6u\x98\xcae\x03mW\xd9\xe4\xb6K\x0c\x1c\xe7\xa0']
+  response: b'Bk\xad\xa5\xc6u\x98\xcae\x03mW\xd9\xe4\xb6K\x0c\x1c\xe7\xa0'
 
   $ cat error.log

tests/test-wireproto-command-pushkey.t

@@ -53,7 +53,7 b' pushkey for a bookmark works'
   received frame(size=*; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor) (glob)
   s>     0\r\n
   s>     \r\n
-  response: [True]
+  response: True
 
   $ sendhttpv2peer << EOF
   > command listkeys
@@ -84,6 +84,6 b' pushkey for a bookmark works'
   received frame(size=45; request=1; stream=2; streamflags=stream-begin; type=bytes-response; flags=eos|cbor)
   s>     0\r\n
   s>     \r\n
-  response: [{b'@': b'426bada5c67598ca65036d57d9e4b64b0c1ce7a0'}]
+  response: {b'@': b'426bada5c67598ca65036d57d9e4b64b0c1ce7a0'}
 
   $ cat error.log