[master 2/3] Add execReadlines to executils.
bcl
installerbot-noreply at redhat.com
Thu Jul 30 16:02:59 UTC 2015
From: "Brian C. Lane" <bcl at redhat.com>
Returns output in realtime instead of buffering it.
---
src/pylorax/executils.py | 110 ++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 105 insertions(+), 5 deletions(-)
diff --git a/src/pylorax/executils.py b/src/pylorax/executils.py
index 313cf77..25c9eef 100644
--- a/src/pylorax/executils.py
+++ b/src/pylorax/executils.py
@@ -20,8 +20,8 @@
import os
import subprocess
+from subprocess import TimeoutExpired
import signal
-from time import sleep
import logging
log = logging.getLogger("pylorax")
@@ -76,6 +76,7 @@ def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subp
:param reset_lang: whether to set the locale of the child process to C
:param kwargs: Additional parameters to pass to subprocess.Popen
:return: A Popen object for the running command.
+ :keyword preexec_fn: A function to run before execution starts.
"""
if env_prune is None:
env_prune = []
@@ -136,6 +137,9 @@ def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_ou
:param filter_stderr: whether to exclude the contents of stderr from the returned output
:param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
:param callback: method to call while waiting for process to finish, passed Popen object
+ :param env_add: environment variables to add before execution
+ :param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
+ :param reset_lang: whether to set the locale of the child process to C
:return: The return code of the command and the output
:raises: OSError or CalledProcessError
"""
@@ -151,9 +155,13 @@ def _run_program(argv, root='/', stdin=None, stdout=None, env_prune=None, log_ou
if callback:
while callback(proc) and proc.poll() is None:
- sleep(1)
-
- (output_string, err_string) = proc.communicate()
+ try:
+ (output_string, err_string) = proc.communicate(timeout=1)
+ break
+ except TimeoutExpired:
+ pass
+ else:
+ (output_string, err_string) = proc.communicate()
if output_string:
if binary_output:
output_lines = [output_string]
@@ -206,6 +214,9 @@ def execWithRedirect(command, argv, stdin=None, stdout=None, root='/', env_prune
:param binary_output: whether to treat the output of command as binary data
:param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
:param callback: method to call while waiting for process to finish, passed Popen object
+ :param env_add: environment variables to add before execution
+ :param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
+ :param reset_lang: whether to set the locale of the child process to C
:return: The return code of the command
"""
argv = [command] + list(argv)
@@ -223,7 +234,10 @@ def execWithCapture(command, argv, stdin=None, root='/', log_output=True, filter
:param root: The directory to chroot to before running command.
:param log_output: Whether to log the output of command
:param filter_stderr: Whether stderr should be excluded from the returned output
- :param raise_err: whether to raise a CalledProcessError if the returncode is non-zero
+ :param callback: method to call while waiting for process to finish, passed Popen object
+ :param env_add: environment variables to add before execution
+ :param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
+ :param reset_lang: whether to set the locale of the child process to C
:return: The output of the command
"""
argv = [command] + list(argv)
@@ -231,6 +245,92 @@ def execWithCapture(command, argv, stdin=None, root='/', log_output=True, filter
raise_err=raise_err, callback=callback, env_add=env_add,
reset_handlers=reset_handlers, reset_lang=reset_lang)[1]
+def execReadlines(command, argv, stdin=None, root='/', env_prune=None, filter_stderr=False,
+ callback=lambda x: True, env_add=None, reset_handlers=True, reset_lang=True):
+ """ Execute an external command and return the line output of the command
+ in real-time.
+
+ This method assumes that there is a reasonably low delay between the
+ end of output and the process exiting. If the child process closes
+ stdout and then keeps on truckin' there will be problems.
+
+ NOTE/WARNING: UnicodeDecodeError will be raised if the output of the
+ external command can't be decoded as UTF-8.
+
+ :param command: The command to run
+ :param argv: The argument list
+ :param stdin: The file object to read stdin from.
+ :param stdout: Optional file object to redirect stdout and stderr to.
+ :param root: The directory to chroot to before running command.
+ :param env_prune: environment variable to remove before execution
+ :param filter_stderr: Whether stderr should be excluded from the returned output
+ :param callback: method to call while waiting for process to finish, passed Popen object
+ :param env_add: environment variables to add before execution
+ :param reset_handlers: whether to reset to SIG_DFL any signal handlers set to SIG_IGN
+ :param reset_lang: whether to set the locale of the child process to C
+ :return: Iterator of the lines from the command
+
+ Output from the file is not logged to program.log
+ This returns an iterator with the lines from the command until it has finished
+ """
+
+ class ExecLineReader(object):
+ """Iterator class for returning lines from a process and cleaning
+ up the process when the output is no longer needed.
+ """
+
+ def __init__(self, proc, argv, callback):
+ self._proc = proc
+ self._argv = argv
+ self._callback = callback
+
+ def __iter__(self):
+ return self
+
+ def __del__(self):
+ # See if the process is still running
+ if self._proc.poll() is None:
+ # Stop the process and ignore any problems that might arise
+ try:
+ self._proc.terminate()
+ except OSError:
+ pass
+
+ def __next__(self):
+ # Read the next line, blocking if a line is not yet available
+ line = self._proc.stdout.readline().decode("utf-8")
+ if line == '' or not self._callback(self._proc):
+ # Output finished, wait for the process to end
+ self._proc.communicate()
+
+ # Check for successful exit
+ if self._proc.returncode < 0:
+ raise OSError("process '%s' was killed by signal %s" %
+ (self._argv, -self._proc.returncode))
+ elif self._proc.returncode > 0:
+ raise OSError("process '%s' exited with status %s" %
+ (self._argv, self._proc.returncode))
+ raise StopIteration
+
+ return line.strip()
+
+ argv = [command] + argv
+
+ if filter_stderr:
+ stderr = subprocess.DEVNULL
+ else:
+ stderr = subprocess.STDOUT
+
+ try:
+ proc = startProgram(argv, root=root, stdin=stdin, stdout=subprocess.PIPE, stderr=stderr, bufsize=1,
+ env_prune=env_prune, env_add=env_add, reset_handlers=reset_handlers, reset_lang=reset_lang)
+ except OSError as e:
+ with program_log_lock:
+ program_log.error("Error running %s: %s", argv[0], e.strerror)
+ raise
+
+ return ExecLineReader(proc, argv, callback)
+
def runcmd(cmd, **kwargs):
""" run execWithRedirect with raise_err=True
"""
--
To view this commit on github, visit https://github.com/rhinstaller/lorax/commit/cfe47770422110265137bcc2248bfd74987d2829
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