Add grpc helpers to python

README.md

@@ -100,9 +100,12 @@ Caveats
  - client: disable secure connection on dialing with `grpc.WithInsecure()`
  - client: set [max gRPC message size](https://github.com/grpc/grpc/issues/7927):
     - go: use `pb.DialContext` instead.
+    - python: use `lookout.sdk.grpc.create_channel` instead.
  - client: turn off [gRPC fail-fast](https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md) mode
    If your analyzer greedy creates a connection to DataServer before one was actually started, you might want to disable fail-fast mode. This way the RPCs are queued until the chanel ready. Here is an [example](https://github.com/src-d/lookout-gometalint-analyzer/blob/7b4b37fb3109299516fbb43017934d131784f49f/cmd/gometalint-analyzer/main.go#L66).
-  - go client/server: use `pb.ToGoGrpcAddress` and `pb.Listen` to support [RFC 3986 URI scheme](https://github.com/grpc/grpc-go/issues/1911)
+  - client/server RFC 3986 URI scheme support:
+    - go: use `pb.ToGoGrpcAddress` and `pb.Listen`
+    - python: use `lookout.sdk.grpc.to_grpc_address`
 
 Release Process
 =================

language-analyzer.py

@@ -1,35 +1,34 @@
 #!/usr/bin/env python3
 
-# Example Analyser gRPC service implementation.
-# Posts file-level comments for every file with language detected.
+"""
+ Example Analyzer gRPC service implementation.
+ Posts file-level comments for every file with language detected.
+"""
 
 from concurrent.futures import ThreadPoolExecutor
 
 import time
 import grpc
 
-from lookout.sdk import service_analyzer_pb2_grpc
+from lookout.sdk import AnalyzerServicer, add_analyzer_to_server
 from lookout.sdk import service_analyzer_pb2
 from lookout.sdk import service_data_pb2_grpc
 from lookout.sdk import service_data_pb2
+from lookout.sdk.grpc import to_grpc_address, create_channel
 
 from bblfsh import filter as filter_uast
 
 port_to_listen = 2021
-data_srv_addr = "localhost:10301"
+data_srv_addr = to_grpc_address("ipv4://localhost:10301")
 version = "alpha"
-grpc_max_msg_size = 100 * 1024 * 1024  # 100mb
 
 
-class Analyzer(service_analyzer_pb2_grpc.AnalyzerServicer):
+class Analyzer(AnalyzerServicer):
     def NotifyReviewEvent(self, request, context):
         print("got review request {}".format(request))
 
         # client connection to DataServe
-        channel = grpc.insecure_channel(data_srv_addr, options=[
-                ("grpc.max_send_message_length", grpc_max_msg_size),
-                ("grpc.max_receive_message_length", grpc_max_msg_size),
-            ])
+        channel = create_channel(data_srv_addr)
         stub = service_data_pb2_grpc.DataStub(channel)
         changes = stub.GetChanges(
             service_data_pb2.ChangesRequest(
@@ -41,7 +40,11 @@ def NotifyReviewEvent(self, request, context):
 
         comments = []
         for change in changes:
-            print("analyzing '{}' in {}".format(change.head.path, change.head.language))
+            if not change.HasField("head"):
+                continue
+
+            print("analyzing '{}' in {}".format(
+                change.head.path, change.head.language))
             fns = list(filter_uast(change.head.uast, "//*[@roleFunction]"))
             comments.append(
                 service_analyzer_pb2.Comment(
@@ -56,11 +59,11 @@ def NotifyPushEvent(self, request, context):
 
 def serve():
     server = grpc.server(thread_pool=ThreadPoolExecutor(max_workers=10))
-    service_analyzer_pb2_grpc.add_AnalyzerServicer_to_server(Analyzer(), server)
+    add_analyzer_to_server(Analyzer(), server)
     server.add_insecure_port("0.0.0.0:{}".format(port_to_listen))
     server.start()
 
-    one_day_sec = 60*60*24
+    one_day_sec = 60 * 60 * 24
     try:
         while True:
             time.sleep(one_day_sec)

python/lookout/__init__.py

@@ -1,3 +1,4 @@
+"""Python SDK for lookout analyzers."""
 # DO NOT CHANGE OR ADD ANYTHING HERE
 import pkg_resources
 pkg_resources.declare_namespace(__name__)

python/lookout/sdk/__init__.py

@@ -0,0 +1,3 @@
+# re-export using pythonic names
+from lookout.sdk.service_analyzer_pb2_grpc import \
+    AnalyzerServicer, add_AnalyzerServicer_to_server as add_analyzer_to_server

python/lookout/sdk/grpc.py

@@ -0,0 +1,28 @@
+from urllib.parse import urlparse
+
+import grpc
+
+grpc_max_msg_size = 100 * 1024 * 1024  # 100MB
+
+
+def create_channel(target, options=None):
+    options = (options or []) + [
+        ("grpc.max_send_message_length", grpc_max_msg_size),
+        ("grpc.max_receive_message_length", grpc_max_msg_size),
+    ]
+    return grpc.insecure_channel(target, options)
+
+
+def to_grpc_address(target):
+    """
+    converts a standard gRPC target name to a one that is supported by grpcio.
+    """
+
+    u = urlparse(target)
+    if u.scheme == "dns":
+        raise ValueError("dns:// not supported")
+
+    if u.scheme == "unix":
+        return "unix:"+u.path
+
+    return u.netloc