Since this thing is on the innerwebs I suppose it should have a

[python_utils.git] / exec_utils.py

diff --git a/exec_utils.py b/exec_utils.py
index 282a325a461e289144b5a58b5a88ce4a90098c83..ae406ef41e925ddbd9ba5483ca1312b5686449e3 100644 (file)
--- a/exec_utils.py
+++ b/exec_utils.py
@@ -1,14 +1,18 @@
 #!/usr/bin/env python3
 
+# © Copyright 2021-2022, Scott Gasch
+
+"""Helper methods concerned with executing subprocesses."""
+
 import atexit
 import logging
+import os
 import selectors
 import shlex
 import subprocess
 import sys
 from typing import List, Optional
 
-
 logger = logging.getLogger(__file__)
 
 
@@ -21,36 +25,40 @@ def cmd_showing_output(
 
     """
     line_enders = set([b'\n', b'\r'])
-    p = subprocess.Popen(
+    sel = selectors.DefaultSelector()
+    with subprocess.Popen(
         command,
         shell=True,
         bufsize=0,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         universal_newlines=False,
-    )
-    sel = selectors.DefaultSelector()
-    sel.register(p.stdout, selectors.EVENT_READ)
-    sel.register(p.stderr, selectors.EVENT_READ)
-    stream_ends = 0
-    while stream_ends < 2:
-        for key, _ in sel.select():
-            char = key.fileobj.read(1)
-            if not char:
-                stream_ends += 1
-                continue
-            if key.fileobj is p.stdout:
-                sys.stdout.buffer.write(char)
-                if char in line_enders:
-                    sys.stdout.flush()
-            else:
-                sys.stderr.buffer.write(char)
-                if char in line_enders:
-                    sys.stderr.flush()
-    p.wait()
-    sys.stdout.flush()
-    sys.stderr.flush()
-    return p.returncode
+    ) as p:
+        sel.register(p.stdout, selectors.EVENT_READ)  # type: ignore
+        sel.register(p.stderr, selectors.EVENT_READ)  # type: ignore
+        done = False
+        while not done:
+            for key, _ in sel.select():
+                char = key.fileobj.read(1)  # type: ignore
+                if not char:
+                    sel.unregister(key.fileobj)
+                    if len(sel.get_map()) == 0:
+                        sys.stdout.flush()
+                        sys.stderr.flush()
+                        sel.close()
+                        done = True
+                if key.fileobj is p.stdout:
+                    # sys.stdout.buffer.write(char)
+                    os.write(sys.stdout.fileno(), char)
+                    if char in line_enders:
+                        sys.stdout.flush()
+                else:
+                    # sys.stderr.buffer.write(char)
+                    os.write(sys.stderr.fileno(), char)
+                    if char in line_enders:
+                        sys.stderr.flush()
+        p.wait()
+        return p.returncode
 
 
 def cmd_with_timeout(command: str, timeout_seconds: Optional[float]) -> int:
@@ -133,7 +141,7 @@ def cmd_in_background(command: str, *, silent: bool = False) -> subprocess.Popen
     def kill_subproc() -> None:
         try:
             if subproc.poll() is None:
-                logger.info("At exit handler: killing {}: {}".format(subproc, command))
+                logger.info('At exit handler: killing %s (%s)', subproc, command)
                 subproc.terminate()
                 subproc.wait(timeout=10.0)
         except BaseException as be: