Merge ~cjwatson/turnip:hookrpc-handle-timeout into turnip:master

[Colin Watson]

Handle timeout errors in hookrpc calls

LP: #1838675

[Jonathan Hartley (tartley)]

Hi Colin! Diffs look good to me, based on a naive scan.

Again though, I don't know turnip or twisted, so on reflection I'll let someone else approve. :-)

[William Grant (wgrant)]

review: Approve (code)

diff --git a/turnip/pack/hookrpc.py b/turnip/pack/hookrpc.py
index 5a73fff..dac851a 100644
--- a/turnip/pack/hookrpc.py
+++ b/turnip/pack/hookrpc.py
@@ -79,8 +79,12 @@ class RPCServerProtocol(JSONNetstringProtocol):
         if op not in self.methods:
             self.sendValue({"error": "Unknown op: %s" % op})
             return
-        res = yield self.methods[op](self, val)
-        self.sendValue({"result": res})
+        try:
+            res = yield self.methods[op](self, val)
+        except defer.TimeoutError:
+            self.sendValue({"error": "%s timed out" % op})
+        else:
+            self.sendValue({"result": res})
 
     def invalidValueReceived(self, string):
         self.sendValue({"error": "Command must be a JSON object"})
diff --git a/turnip/pack/tests/test_hookrpc.py b/turnip/pack/tests/test_hookrpc.py
index 5aec94b..2a56054 100644
--- a/turnip/pack/tests/test_hookrpc.py
+++ b/turnip/pack/tests/test_hookrpc.py
@@ -105,6 +105,10 @@ def sync_rpc_method(proto, args):
     return list(args.items())
 
 
+def timeout_rpc_method(proto, args):
+    raise defer.TimeoutError()
+
+
 class TestRPCServerProtocol(TestCase):
     """Test the socket server that handles git hook callbacks."""
 
@@ -113,6 +117,7 @@ class TestRPCServerProtocol(TestCase):
         self.proto = hookrpc.RPCServerProtocol({
             'sync': sync_rpc_method,
             'async': async_rpc_method,
+            'timeout': timeout_rpc_method,
             })
         self.transport = proto_helpers.StringTransportWithDisconnection()
         self.transport.protocol = self.proto
@@ -150,6 +155,11 @@ class TestRPCServerProtocol(TestCase):
             b'42:{"error": "Command must be a JSON object"},',
             self.transport.value())
 
+    def test_timeout(self):
+        self.proto.dataReceived(b'31:{"op": "timeout", "bar": "baz"},')
+        self.assertEqual(
+            b'30:{"error": "timeout timed out"},', self.transport.value())
+
 
 class TestHookRPCHandler(TestCase):
     """Test the hook RPC handler."""