386 lines
11 KiB
Python
386 lines
11 KiB
Python
"""Easy to use python subprocess interface."""
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import logging
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import os.path
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import subprocess
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import tempfile
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import time
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from typing import Any, List, Optional, Union
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from easyprocess.about import __version__
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from easyprocess.unicodeutil import split_command, unidecode
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log = logging.getLogger(__name__)
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log.debug("version=%s", __version__)
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class EasyProcessError(Exception):
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def __init__(self, easy_process, msg=""):
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self.easy_process = easy_process
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self.msg = msg
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def __str__(self):
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return self.msg + " " + repr(self.easy_process)
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def _rm_ending_lf(s):
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if s.endswith("\n"):
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s = s[:-1]
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if s.endswith("\r"):
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s = s[:-1]
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return s
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class EasyProcess(object):
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"""
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.. module:: easyprocess
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simple interface for :mod:`subprocess`
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shell is not supported (shell=False)
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.. warning::
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unicode is supported only for string list command (Python2.x)
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(check :mod:`shlex` for more information)
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:param cmd: string ('ls -l') or list of strings (['ls','-l'])
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:param cwd: working directory
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:param use_temp_files: use temp files (True) or pipes (False) for stdout and stderr,
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pipes can cause deadlock in some cases (see unit tests)
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:param env: If *env* is not ``None``, it must be a mapping that defines the environment
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variables for the new process; these are used instead of inheriting the current
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process' environment, which is the default behavior.
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(check :mod:`subprocess` for more information)
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"""
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def __init__(
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self,
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cmd: Union[List[str], str],
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cwd: Optional[str] = None,
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use_temp_files: bool = True,
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env=None,
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):
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self.use_temp_files = use_temp_files
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# for testing
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EASYPROCESS_USE_TEMP_FILES = os.environ.get("EASYPROCESS_USE_TEMP_FILES")
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if EASYPROCESS_USE_TEMP_FILES:
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log.debug("EASYPROCESS_USE_TEMP_FILES=%s", EASYPROCESS_USE_TEMP_FILES)
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# '0'->false, '1'->true
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self.use_temp_files = bool(int(EASYPROCESS_USE_TEMP_FILES))
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self._outputs_processed = False
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self.env = env
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self.popen: Optional[subprocess.Popen] = None
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self.stdout = None
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self.stderr = None
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self._stdout_file: Any = None
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self._stderr_file: Any = None
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self.is_started = False
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self.oserror: Optional[OSError] = None
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self.cmd_param = cmd
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# self._thread: Optional[threading.Thread] = None
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self.timeout_happened = False
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self.cwd = cwd
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self.cmd = split_command(cmd)
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# self.cmd_as_string = " ".join(self.cmd)
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self.enable_stdout_log = True
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self.enable_stderr_log = True
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# log.debug('param: "%s" ', self.cmd_param)
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log.debug("command: %s", self.cmd)
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# log.debug('joined command: %s', self.cmd_as_string)
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if not len(self.cmd):
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raise EasyProcessError(self, "empty command!")
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def __repr__(self):
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msg = '<%s cmd_param=%s cmd=%s oserror=%s return_code=%s stdout="%s" stderr="%s" timeout_happened=%s>' % (
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self.__class__.__name__,
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self.cmd_param,
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self.cmd,
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self.oserror,
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self.return_code,
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self.stdout,
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self.stderr,
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self.timeout_happened,
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)
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return msg
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@property
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def pid(self) -> Optional[int]:
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"""
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PID (:attr:`subprocess.Popen.pid`)
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:rtype: int
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"""
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if self.popen:
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return self.popen.pid
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return None
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@property
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def return_code(self) -> Optional[int]:
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"""
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returncode (:attr:`subprocess.Popen.returncode`)
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:rtype: int
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"""
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if self.popen:
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return self.popen.returncode
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return None
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def call(self, timeout: Optional[float] = None) -> "EasyProcess":
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"""Run command with arguments. Wait for command to complete.
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same as:
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1. :meth:`start`
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2. :meth:`wait`
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3. :meth:`stop`
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:rtype: self
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"""
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try:
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self.start().wait(timeout=timeout)
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finally:
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if self.is_alive():
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self.stop()
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return self
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def start(self) -> "EasyProcess":
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"""start command in background and does not wait for it.
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:rtype: self
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"""
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if self.is_started:
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raise EasyProcessError(self, "process was started twice!")
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stdout: Any = None
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stderr: Any = None
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if self.use_temp_files:
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self._stdout_file = tempfile.TemporaryFile(prefix="stdout_")
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self._stderr_file = tempfile.TemporaryFile(prefix="stderr_")
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stdout = self._stdout_file
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stderr = self._stderr_file
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else:
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stdout = subprocess.PIPE
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stderr = subprocess.PIPE
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# cmd = list(map(uniencode, self.cmd))
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try:
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self.popen = subprocess.Popen(
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self.cmd,
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stdout=stdout,
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stderr=stderr,
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cwd=self.cwd,
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env=self.env,
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)
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except OSError as oserror:
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log.debug("OSError exception: %s", oserror)
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self.oserror = oserror
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raise EasyProcessError(self, "start error")
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self.is_started = True
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log.debug("process was started (pid=%s)", self.pid)
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return self
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def is_alive(self) -> bool:
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"""
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poll process using :meth:`subprocess.Popen.poll`
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It updates stdout/stderr/return_code if process has stopped earlier.
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:rtype: bool
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"""
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if self.popen:
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alive = self.popen.poll() is None
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if not alive:
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# collect stdout/stderr/return_code if proc stopped
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self._wait4process()
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return alive
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else:
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return False
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def wait(self, timeout: Optional[float] = None) -> "EasyProcess":
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"""Wait for command to complete.
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:rtype: self
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"""
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# Timeout (threading) discussion: https://stackoverflow.com/questions/1191374/subprocess-with-timeout
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self._wait4process(timeout)
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# if timeout is not None:
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# if not self._thread:
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# self._thread = threading.Thread(target=self._wait4process)
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# self._thread.daemon = True
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# self._thread.start()
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# if self._thread:
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# self._thread.join(timeout=timeout)
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# self.timeout_happened = self.timeout_happened or self._thread.is_alive()
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# else:
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# # no timeout and no existing thread
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# self._wait4process()
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return self
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def _wait4process(self, timeout=None):
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if self._outputs_processed:
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return
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if not self.popen:
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return
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if self.use_temp_files:
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try:
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self.popen.wait(timeout=timeout)
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except subprocess.TimeoutExpired:
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self.timeout_happened = True
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log.debug("timeout")
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return
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self._stdout_file.seek(0)
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self._stderr_file.seek(0)
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self.stdout = self._stdout_file.read()
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self.stderr = self._stderr_file.read()
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self._stdout_file.close()
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self._stderr_file.close()
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else:
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# This will deadlock when using stdout=PIPE and/or stderr=PIPE
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# and the child process generates enough output to a pipe such
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# that it blocks waiting for the OS pipe buffer to accept more data.
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# Use communicate() to avoid that.
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# self.popen.wait()
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# self.stdout = self.popen.stdout.read()
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# self.stderr = self.popen.stderr.read()
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try:
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(self.stdout, self.stderr) = self.popen.communicate(timeout=timeout)
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except subprocess.TimeoutExpired:
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self.timeout_happened = True
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log.debug("timeout")
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return
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log.debug("process has ended, return code=%s", self.return_code)
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self.stdout = _rm_ending_lf(unidecode(self.stdout))
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self.stderr = _rm_ending_lf(unidecode(self.stderr))
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self._outputs_processed = True
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# def limit_str(s):
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# if len(s) > self.max_bytes_to_log:
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# warn = '[middle of output was removed, max_bytes_to_log=%s]'%(self.max_bytes_to_log)
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# s = s[:self.max_bytes_to_log / 2] + warn + s[-self.max_bytes_to_log / 2:]
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# return s
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if self.enable_stdout_log:
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log.debug("stdout=%s", self.stdout)
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if self.enable_stderr_log:
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log.debug("stderr=%s", self.stderr)
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def stop(self) -> "EasyProcess":
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"""Kill process and wait for command to complete.
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same as:
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1. :meth:`sendstop`
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2. :meth:`wait`
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:rtype: self
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"""
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self.sendstop().wait()
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# if self.is_alive() and kill_after is not None:
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# self.sendstop(kill=True).wait()
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return self
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def sendstop(self) -> "EasyProcess":
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"""
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Kill process (:meth:`subprocess.Popen.terminate`).
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Do not wait for command to complete.
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:rtype: self
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"""
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if not self.is_started:
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raise EasyProcessError(self, "process was not started!")
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log.debug('stopping process (pid=%s cmd="%s")', self.pid, self.cmd)
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if self.popen:
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if self.is_alive():
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log.debug("process is active -> calling kill()")
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self.popen.kill()
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# signame = "SIGKILL" if kill else "SIGTERM"
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# log.debug("process is active -> sending " + signame)
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# try:
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# try:
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# if kill:
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# self.popen.kill()
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# else:
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# self.popen.terminate()
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# except AttributeError:
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# os.kill(self.popen.pid, signal.SIGKILL)
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# except OSError as oserror:
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# log.debug("exception in terminate:%s", oserror)
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else:
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log.debug("process was already stopped")
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else:
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log.debug("process was not started")
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return self
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def sleep(self, sec: float) -> "EasyProcess":
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"""
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sleeping (same as :func:`time.sleep`)
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:rtype: self
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"""
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time.sleep(sec)
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return self
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def wrap(self, func, delay=0):
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"""
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returns a function which:
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1. start process
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2. call func, save result
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3. stop process
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4. returns result
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similar to :keyword:`with` statement
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:rtype:
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"""
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def wrapped():
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self.start()
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if delay:
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self.sleep(delay)
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x = None
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try:
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x = func()
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except OSError as oserror:
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log.debug("OSError exception:%s", oserror)
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self.oserror = oserror
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raise EasyProcessError(self, "wrap error!")
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finally:
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self.stop()
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return x
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return wrapped
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def __enter__(self):
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"""used by the :keyword:`with` statement"""
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self.start()
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return self
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def __exit__(self, *exc_info):
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"""used by the :keyword:`with` statement"""
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self.stop()
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