From f3c6d91e69d88b86c13e5d1c6ba979e45bdd4354 Mon Sep 17 00:00:00 2001
From: Tim Abbott <tabbott@zulipchat.com>
Date: Sun, 16 Dec 2018 20:49:33 -0800
Subject: [PATCH] mypy: Switch default to daemon mode.

There isn't any real advantage to running the non-daemon mode at this
point.
---
 docs/contributing/mypy.md | 18 +++++++-----------
 tools/ci/backend          |  4 +++-
 tools/run-mypy            | 10 +++++-----
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/docs/contributing/mypy.md b/docs/contributing/mypy.md
index 849e0b8180..b7afd4b53c 100644
--- a/docs/contributing/mypy.md
+++ b/docs/contributing/mypy.md
@@ -114,19 +114,15 @@ To run mypy on Zulip's python code, you can run the command:
 
     tools/run-mypy
 
-You can also run mypy as a long-running daemon (server) process and send
-type-checking requests to the server via the command:
+This will take a while to start running, since it runs mypy as a
+long-running daemon (server) process and send type-checking requests
+to the server; this makes checking mypy about 100x faster.  But if
+you're debugging or for whatever reason don't want the daemon, you can
+use:
 
-    tools/run-mypy -d
+    tools/run-mypy --no-daemon
 
-While the mypy daemon is experimental and currently supports macOS and Linux
-only, **we strongly recommend using the daemon** if it is an option. Program
-state from previous runs will be cached in memory and will not have to be
-read from the file system on each run. For a  large codebase like Zulip's
-and a  workflow involving running mypy repeatedly after small edits, using
-the daemon can be *10 or more times faster*.
-
-Mypy will output errors in the same style as a compiler would.  For
+Mypy outputs errors in the same style as a compiler would.  For
 example, if your code has a type error like this:
 
 ```
diff --git a/tools/ci/backend b/tools/ci/backend
index 35e24295be..2b2de42ba5 100755
--- a/tools/ci/backend
+++ b/tools/ci/backend
@@ -13,7 +13,9 @@ set -x
 # We run mypy after the backend tests so we get output from the
 # backend tests, which tend to uncover more serious problems, first.
 ./tools/run-mypy --version
-./tools/run-mypy
+# We run mypy without daemon mode, since that's faster given that
+# we're only going to run it once.
+./tools/run-mypy --no-daemon
 
 ./tools/test-migrations
 ./tools/setup/optimize-svg
diff --git a/tools/run-mypy b/tools/run-mypy
index 7a0d3150a8..c90789719c 100755
--- a/tools/run-mypy
+++ b/tools/run-mypy
@@ -28,7 +28,7 @@ parser.add_argument('--quick', action='store_true',
                     help="pass --quick to mypy")
 parser.add_argument('-m', '--modified', action='store_true',
                     help="check only modified files")
-parser.add_argument('-d', '--daemon', action='store_true',
+parser.add_argument('--no-daemon', action='store_true',
                     help="Start and run the mypy fine-grained incremental daemon")
 parser.add_argument('--scripts-only', action='store_true',
                     help="only check extensionless python scripts")
@@ -45,7 +45,7 @@ if not args.force:
         print('If you really know what you are doing, use --force to run anyway.')
         sys.exit(1)
 
-command_name = "mypy" if not args.daemon else "dmypy"
+command_name = "mypy" if (args.no_daemon or args.version) else "dmypy"
 
 # Use zulip-py3-venv's mypy if it's available.
 VENV_DIR = "/srv/zulip-py3-venv"
@@ -80,10 +80,10 @@ if args.quick:
     extra_args.append("--quick")
 
 mypy_args = extra_args + python_files + pyi_files
-if args.daemon:
-    rc = subprocess.call([mypy_command, 'run', '--'] + mypy_args)
-else:
+if args.no_daemon:
     rc = subprocess.call([mypy_command] + mypy_args)
+else:
+    rc = subprocess.call([mypy_command, 'run', '--'] + mypy_args)
 
 if rc != 0:
     print("")