SeleniumBase/seleniumbase/virtual_display/easyprocess.py

"""Easy to use python subprocess interface."""

from seleniumbase.virtual_display.unicodeutil import (split_command,
                                                      unidecode,
                                                      uniencode)
import logging
import os.path
import platform
import signal
import subprocess
import tempfile
import threading
import time

log = logging.getLogger(__name__)
log.setLevel(logging.ERROR)
SECTION_LINK = 'link'
POLL_TIME = 0.1
USE_POLL = 0


class EasyProcessError(Exception):

    def __init__(self, easy_process, msg=''):
        self.easy_process = easy_process
        self.msg = msg

    def __str__(self):
        return self.msg + ' ' + repr(self.easy_process)


template = '''cmd=%s
OSError=%s
Program install error! '''


class EasyProcessCheckInstalledError(Exception):

    """This exception is raised when a process run by check() returns
    a non-zero exit status or OSError is raised.
    """

    def __init__(self, easy_process):
        self.easy_process = easy_process

    def __str__(self):
        msg = template % (self.easy_process.cmd,
                          self.easy_process.oserror,
                          )
        if self.easy_process.url:
            msg += '\nhome page: ' + self.easy_process.url
        if platform.dist()[0].lower() == 'ubuntu':
            if self.easy_process.ubuntu_package:
                msg += '\nYou can install it in terminal:\n'
                msg += ('sudo apt-get install '
                        '%s' % self.easy_process.ubuntu_package)
        return msg


class EasyProcess(object):

    '''
    .. module:: easyprocess

    simple interface for :mod:`subprocess`

    shell is not supported (shell=False)

    .. warning::

      unicode is supported only for string list command (Python2.x)
      (check :mod:`shlex` for more information)

    :param cmd: string ('ls -l') or list of strings (['ls','-l'])
    :param cwd: working directory
    :param use_temp_files: use temp files instead of pipes for
                           stdout and stderr,
                           pipes can cause deadlock in some cases
                           (see unit tests)

    :param env: If *env* is not ``None``, it must be a mapping that defines
                the environment variables for the new process;
                these are used instead of inheriting the current
                process' environment, which is the default behavior.
                (check :mod:`subprocess`  for more information)
    '''

    def __init__(self, cmd, ubuntu_package=None, url=None,
                 cwd=None, use_temp_files=True, env=None):
        self.use_temp_files = use_temp_files
        self._outputs_processed = False
        self.env = env
        self.popen = None
        self.stdout = None
        self.stderr = None
        self._stdout_file = None
        self._stderr_file = None
        self.url = url
        self.ubuntu_package = ubuntu_package
        self.is_started = False
        self.oserror = None
        self.cmd_param = cmd
        self._thread = None
        self._stop_thread = False
        self.timeout_happened = False
        self.cwd = cwd
        cmd = split_command(cmd)
        self.cmd = cmd
        self.cmd_as_string = ' '.join(self.cmd)  # TODO: not perfect
        log.debug('param: "%s" ', self.cmd_param)
        log.debug('command: %s', self.cmd)
        log.debug('joined command: %s', self.cmd_as_string)
        if not len(cmd):
            raise EasyProcessError(self, 'empty command!')

    def __repr__(self):
        msg = ('<%s cmd_param=%s cmd=%s oserror=%s return_code=%s'
               ' stdout="%s" stderr="%s" timeout_happened=%s>' % (
                   self.__class__.__name__,
                   self.cmd_param,
                   self.cmd,
                   self.oserror,
                   self.return_code,
                   self.stdout,
                   self.stderr,
                   self.timeout_happened,
               ))
        return msg

    @property
    def pid(self):
        '''
        PID (:attr:`subprocess.Popen.pid`)

        :rtype: int
        '''
        if self.popen:
            return self.popen.pid

    @property
    def return_code(self):
        '''
        returncode (:attr:`subprocess.Popen.returncode`)

        :rtype: int
        '''
        if self.popen:
            return self.popen.returncode

    def check(self, return_code=0):
        """Run command with arguments. Wait for command to complete. If the
        exit code was as expected and there is no exception then return,
        otherwise raise EasyProcessError.

        :param return_code: int, expected return code
        :rtype: self

        """
        ret = self.call().return_code
        ok = ret == return_code
        if not ok:
            raise EasyProcessError(
                self, 'check error, return code is not {0}!'.format(
                    return_code))
        return self

    def check_installed(self):
        """Used for testing if program is installed.

        Run command with arguments. Wait for command to complete.
        If OSError raised, then raise :class:`EasyProcessCheckInstalledError`
        with information about program installation

        :param return_code: int, expected return code
        :rtype: self

        """
        try:
            self.call()
        except Exception:
            raise EasyProcessCheckInstalledError(self)
        return self

    def call(self, timeout=None):
        """Run command with arguments. Wait for command to complete.

        same as:
         1. :meth:`start`
         2. :meth:`wait`
         3. :meth:`stop`

        :rtype: self

        """
        self.start().wait(timeout=timeout)
        if self.is_alive():
            self.stop()
        return self

    def start(self):
        """start command in background and does not wait for it.

        :rtype: self

        """
        if self.is_started:
            raise EasyProcessError(self, 'process was started twice!')

        if self.use_temp_files:
            self._stdout_file = tempfile.TemporaryFile(prefix='stdout_')
            self._stderr_file = tempfile.TemporaryFile(prefix='stderr_')
            stdout = self._stdout_file
            stderr = self._stderr_file

        else:
            stdout = subprocess.PIPE
            stderr = subprocess.PIPE

        cmd = list(map(uniencode, self.cmd))

        try:
            self.popen = subprocess.Popen(cmd,
                                          stdout=stdout,
                                          stderr=stderr,
                                          cwd=self.cwd,
                                          env=self.env,
                                          )
        except OSError as oserror:
            log.debug('OSError exception: %s', oserror)
            self.oserror = oserror
            raise EasyProcessError(self, 'start error')
        self.is_started = True
        log.debug('process was started (pid=%s)', self.pid)
        return self

    def is_alive(self):
        '''
        poll process using :meth:`subprocess.Popen.poll`

        :rtype: bool
        '''
        if self.popen:
            return self.popen.poll() is None
        else:
            return False

    def wait(self, timeout=None):
        """Wait for command to complete.

        Timeout:
         - discussion:
           http://stackoverflow.com/questions/1191374/subprocess-with-timeout
         - implementation: threading

        :rtype: self

        """

        if timeout is not None:
            if not self._thread:
                self._thread = threading.Thread(target=self._wait4process)
                self._thread.daemon = 1
                self._thread.start()

        if self._thread:
            self._thread.join(timeout=timeout)
            self.timeout_happened = (
                self.timeout_happened or self._thread.isAlive())
        else:
            # no timeout and no existing thread
            self._wait4process()
        return self

    def _wait4process(self):
        if self._outputs_processed:
            return

        def remove_ending_lf(s):
            if s.endswith('\n'):
                return s[:-1]
            else:
                return s

        if self.popen:
            if self.use_temp_files:
                if USE_POLL:
                    while True:
                        if self.popen.poll() is not None:
                            break
                        if self._stop_thread:
                            return
                        time.sleep(POLL_TIME)

                else:
                    # wait() blocks process, timeout not possible
                    self.popen.wait()

                self._outputs_processed = True
                self._stdout_file.seek(0)
                self._stderr_file.seek(0)
                self.stdout = self._stdout_file.read()
                self.stderr = self._stderr_file.read()

                self._stdout_file.close()
                self._stderr_file.close()
            else:
                # This will deadlock when using stdout=PIPE and/or stderr=PIPE
                # and the child process generates enough output to a pipe such
                # that it blocks waiting for the OS pipe buffer
                # to accept more data.
                # Use communicate() to avoid that.
                # self.popen.wait()
                # self.stdout = self.popen.stdout.read()
                # self.stderr = self.popen.stderr.read()

                # communicate() blocks process, timeout not possible
                self._outputs_processed = True
                (self.stdout, self.stderr) = self.popen.communicate()
            log.debug('process has ended')
            self.stdout = remove_ending_lf(unidecode(self.stdout))
            self.stderr = remove_ending_lf(unidecode(self.stderr))
            log.debug('return code=%s', self.return_code)
            log.debug('stdout=%s', self.stdout)
            log.debug('stderr=%s', self.stderr)

    def stop(self):
        """Kill process and wait for command to complete.

        same as:
         1. :meth:`sendstop`
         2. :meth:`wait`

        :rtype: self

        """
        return self.sendstop().wait()

    def sendstop(self):
        '''
        Kill process (:meth:`subprocess.Popen.terminate`).
        Do not wait for command to complete.

        :rtype: self
        '''
        if not self.is_started:
            raise EasyProcessError(self, 'process was not started!')

        log.debug('stopping process (pid=%s cmd="%s")', self.pid, self.cmd)
        if self.popen:
            if self.is_alive():
                log.debug('process is active -> sending SIGTERM')

                try:
                    try:
                        self.popen.terminate()
                    except AttributeError:
                        os.kill(self.popen.pid, signal.SIGKILL)
                except OSError as oserror:
                    log.debug('exception in terminate:%s', oserror)

            else:
                log.debug('process was already stopped')
        else:
            log.debug('process was not started')

        return self

    def sleep(self, sec):
        '''
        sleeping (same as :func:`time.sleep`)

        :rtype: self
        '''
        time.sleep(sec)

        return self

    def wrap(self, func, delay=0):
        '''
        returns a function which:
         1. start process
         2. call func, save result
         3. stop process
         4. returns result

        similar to :keyword:`with` statement

        :rtype:
        '''
        def wrapped():
            self.start()
            if delay:
                self.sleep(delay)
            x = None
            try:
                x = func()
            except OSError as oserror:
                log.debug('OSError exception:%s', oserror)
                self.oserror = oserror
                raise EasyProcessError(self, 'wrap error!')
            finally:
                self.stop()
            return x
        return wrapped

    def __enter__(self):
        '''used by the :keyword:`with` statement'''
        self.start()
        return self

    def __exit__(self, *exc_info):
        '''used by the :keyword:`with` statement'''
        self.stop()


def extract_version(txt):
    """This function tries to extract the version from the help text of any
    program."""
    words = txt.replace(',', ' ').split()
    version = None
    for x in reversed(words):
        if len(x) > 2:
            if x[0].lower() == 'v':
                x = x[1:]
            if '.' in x and x[0].isdigit():
                version = x
                break
    return version


Proc = EasyProcess