X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=exec_utils.py;h=df273352bb793d59f19717c9cb6806134dd5a628;hb=31c81f6539969a5eba864d3305f9fb7bf716a367;hp=b52f52f0dc785033fc437a638c734d79cf8d5aa8;hpb=b29be4f1750fd20bd2eada88e751dfae85817882;p=python_utils.git

diff --git a/exec_utils.py b/exec_utils.py
index b52f52f..df27335 100644
--- a/exec_utils.py
+++ b/exec_utils.py
@@ -2,31 +2,66 @@
 
 import atexit
 import logging
+import os
+import selectors
 import shlex
 import subprocess
+import sys
 from typing import List, Optional
 
-
 logger = logging.getLogger(__file__)
 
 
-def cmd_showing_output(command: str) -> None:
-    p = subprocess.Popen(
+def cmd_showing_output(
+    command: str,
+) -> int:
+    """Kick off a child process.  Capture and print all output that it
+    produces on stdout and stderr.  Wait for the subprocess to exit
+    and return the exit value as the return code of this function.
+
+    """
+    line_enders = set([b'\n', b'\r'])
+    sel = selectors.DefaultSelector()
+    with subprocess.Popen(
         command,
         shell=True,
         bufsize=0,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
-    )
-    for line in iter(p.stdout.readline, b''):
-        print(line.decode('utf-8'), end='')
-    p.stdout.close()
-    p.wait()
+        universal_newlines=False,
+    ) 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:
-    """
-    Run a command but do not let it run for more than timeout seconds.
+    """Run a command but do not let it run for more than timeout seconds.
+    Doesn't capture or rebroadcast command output.  Function returns
+    the exit value of the command or raises a TimeoutExpired exception
+    if the deadline is exceeded.
 
     >>> cmd_with_timeout('/bin/echo foo', 10.0)
     0
@@ -37,14 +72,13 @@ def cmd_with_timeout(command: str, timeout_seconds: Optional[float]) -> int:
     subprocess.TimeoutExpired: Command '['/bin/bash', '-c', '/bin/sleep 2']' timed out after 0.1 seconds
 
     """
-    return subprocess.check_call(
-        ["/bin/bash", "-c", command], timeout=timeout_seconds
-    )
+    return subprocess.check_call(["/bin/bash", "-c", command], timeout=timeout_seconds)
 
 
 def cmd(command: str, timeout_seconds: Optional[float] = None) -> str:
-    """Run a command with everything encased in a string and return
-    the output text as a string.  Raises subprocess.CalledProcessError.
+    """Run a command and capture its output to stdout (only) in a string.
+    Return that string as this function's output.  Raises
+    subprocess.CalledProcessError or TimeoutExpired on error.
 
     >>> cmd('/bin/echo foo')[:-1]
     'foo'
@@ -56,12 +90,16 @@ def cmd(command: str, timeout_seconds: Optional[float] = None) -> str:
 
     """
     ret = subprocess.run(
-        command, shell=True, capture_output=True, check=True, timeout=timeout_seconds,
+        command,
+        shell=True,
+        capture_output=True,
+        check=True,
+        timeout=timeout_seconds,
     ).stdout
     return ret.decode("utf-8")
 
 
-def run_silently(command: str) -> None:
+def run_silently(command: str, timeout_seconds: Optional[float] = None) -> None:
     """Run a command silently but raise subprocess.CalledProcessError if
     it fails.
 
@@ -74,31 +112,37 @@ def run_silently(command: str) -> None:
 
     """
     subprocess.run(
-        command, shell=True, stderr=subprocess.DEVNULL,
-        stdout=subprocess.DEVNULL, capture_output=False, check=True
+        command,
+        shell=True,
+        stderr=subprocess.DEVNULL,
+        stdout=subprocess.DEVNULL,
+        capture_output=False,
+        check=True,
+        timeout=timeout_seconds,
     )
 
 
-def cmd_in_background(
-        command: str, *, silent: bool = False
-) -> subprocess.Popen:
+def cmd_in_background(command: str, *, silent: bool = False) -> subprocess.Popen:
     args = shlex.split(command)
     if silent:
-        subproc = subprocess.Popen(args,
-                                   stdin=subprocess.DEVNULL,
-                                   stdout=subprocess.DEVNULL,
-                                   stderr=subprocess.DEVNULL)
+        subproc = subprocess.Popen(
+            args,
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
     else:
         subproc = subprocess.Popen(args, stdin=subprocess.DEVNULL)
 
     def kill_subproc() -> None:
         try:
             if subproc.poll() is None:
-                logger.info("At exit handler: killing {}: {}".format(subproc, command))
+                logger.info(f'At exit handler: killing {subproc} ({command})')
                 subproc.terminate()
                 subproc.wait(timeout=10.0)
         except BaseException as be:
             logger.exception(be)
+
     atexit.register(kill_subproc)
     return subproc
 
@@ -113,4 +157,5 @@ def cmd_list(command: List[str]) -> str:
 
 if __name__ == '__main__':
     import doctest
+
     doctest.testmod()