python: Simplify stdio flushing using print(…, flush=True).

Signed-off-by: Anders Kaseorg <anders@zulip.com>

scripts/lib/zulip_tools.py

@@ -198,9 +198,9 @@ def get_deployment_lock(error_rerun_script: str) -> None:
                 WARNING
                 + "Another deployment in progress; waiting for lock... "
                 + "(If no deployment is running, rmdir {})".format(LOCK_DIR)
-                + ENDC
+                + ENDC,
+                flush=True,
             )
-            sys.stdout.flush()
             time.sleep(3)
 
     if not got_lock:

tools/lib/test_server.py

@@ -78,18 +78,17 @@ def test_server_running(
 
     try:
         # Wait for the server to start up.
-        sys.stdout.write("\nWaiting for test server (may take a while)")
+        print(end="\nWaiting for test server (may take a while)")
         if not dots:
-            sys.stdout.write("\n\n")
+            print("\n", flush=True)
         t = time.time()
         while not server_is_up(server, log_file):
             if dots:
-                sys.stdout.write(".")
-                sys.stdout.flush()
+                print(end=".", flush=True)
             time.sleep(0.4)
             if time.time() - t > MAX_SERVER_WAIT:
                 raise Exception("Timeout waiting for server")
-        sys.stdout.write("\n\n--- SERVER IS UP! ---\n\n")
+        print("\n\n--- SERVER IS UP! ---\n", flush=True)
 
         # DO OUR ACTUAL TESTING HERE!!!
         yield

zerver/management/commands/export.py

@@ -1,5 +1,4 @@
 import os
-import sys
 import tempfile
 from argparse import ArgumentParser
 from typing import Any
@@ -207,8 +206,7 @@ class Command(ZulipBaseCommand):
             do_deactivate_realm(realm, acting_user=None)
 
         def percent_callback(bytes_transferred: Any) -> None:
-            sys.stdout.write(".")
-            sys.stdout.flush()
+            print(end=".", flush=True)
 
         # Allows us to trigger exports separately from command line argument parsing
         export_realm_wrapper(

zerver/migrations/0177_user_message_add_and_index_is_private_flag.py

@@ -1,7 +1,5 @@
 # Generated by Django 1.11.13 on 2018-06-14 13:39
 
-import sys
-
 import bitfield.models
 from django.db import migrations
 from django.db.backends.postgresql.schema import DatabaseSchemaEditor
@@ -19,8 +17,7 @@ def reset_is_private_flag(apps: StateApps, schema_editor: DatabaseSchemaEditor)
 
     i = 0
     total = len(user_profile_ids)
-    print("Setting default values for the new flag...")
-    sys.stdout.flush()
+    print("Setting default values for the new flag...", flush=True)
     for user_id in user_profile_ids:
         while True:
             # Ideally, we'd just do a single database query per user.
@@ -45,8 +42,7 @@ def reset_is_private_flag(apps: StateApps, schema_editor: DatabaseSchemaEditor)
         i += 1
         if i % 50 == 0 or i == total:
             percent = round((i / total) * 100, 2)
-            print(f"Processed {i}/{total} {percent}%")
-            sys.stdout.flush()
+            print(f"Processed {i}/{total} {percent}%", flush=True)
 
 
 class Migration(migrations.Migration):

zerver/migrations/0182_set_initial_value_is_private_flag.py

@@ -1,5 +1,3 @@
-import sys
-
 from django.db import migrations
 from django.db.backends.postgresql.schema import DatabaseSchemaEditor
 from django.db.migrations.state import StateApps
@@ -19,8 +17,7 @@ def set_initial_value_of_is_private_flag(
     total = Message.objects.filter(recipient__type__in=[1, 3]).count()
     processed = 0
 
-    print("\nStart setting initial value for is_private flag...")
-    sys.stdout.flush()
+    print("\nStart setting initial value for is_private flag...", flush=True)
     while True:
         range_end = i + 10000
         # Can't use [Recipient.PERSONAL, Recipient.HUDDLE] in migration files
@@ -41,8 +38,7 @@ def set_initial_value_of_is_private_flag(
             percent = round((processed / total) * 100, 2)
         else:
             percent = 100.00
-        print(f"Processed {processed}/{total} {percent}%")
-        sys.stdout.flush()
+        print(f"Processed {processed}/{total} {percent}%", flush=True)
 
 
 class Migration(migrations.Migration):

zerver/tests/test_events.py

@@ -5,7 +5,6 @@
 # and zerver/lib/data_types.py systems for validating the schemas of
 # events; it also uses the OpenAPI tools to validate our documentation.
 import copy
-import sys
 import time
 from io import StringIO
 from typing import Any, Callable, Dict, List, Optional, Set
@@ -389,10 +388,10 @@ class BaseAction(ZulipTestCase):
                     we apply events after fetching data.  If you
                     do not know how to debug it, you can ask for
                     help on chat.
-                """
+                """,
+                flush=True,
             )
 
-            sys.stdout.flush()
             raise AssertionError("Mismatching states")