Source code for selenium.webdriver.common.service

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import errno
import logging
import os
import subprocess
import typing
from abc import ABC
from abc import abstractmethod
from io import IOBase
from platform import system
from subprocess import PIPE
from time import sleep
from urllib import request
from urllib.error import URLError

from selenium.common.exceptions import WebDriverException
from selenium.types import SubprocessStdAlias
from selenium.webdriver.common import utils

logger = logging.getLogger(__name__)

[docs]class Service(ABC): """The abstract base class for all service objects. Services typically launch a child program in a new process as an interim process to communicate with a browser. :param executable: install path of the executable. :param port: Port for the service to run on, defaults to 0 where the operating system will decide. :param log_output: (Optional) int representation of STDOUT/DEVNULL, any IO instance or String path to file. :param env: (Optional) Mapping of environment variables for the new process, defaults to `os.environ`. """ def __init__( self, executable_path: str = None, port: int = 0, log_output: SubprocessStdAlias = None, env: typing.Optional[typing.Mapping[typing.Any, typing.Any]] = None, **kwargs, ) -> None: if isinstance(log_output, str): self.log_output = open(log_output, "a+", encoding="utf-8") elif log_output == subprocess.STDOUT: self.log_output = None elif log_output is None or log_output == subprocess.DEVNULL: self.log_output = subprocess.DEVNULL else: self.log_output = log_output self._path = executable_path self.port = port or utils.free_port() # Default value for every python subprocess: subprocess.Popen(..., creationflags=0) self.popen_kw = kwargs.pop("popen_kw", {}) self.creation_flags = self.popen_kw.pop("creation_flags", 0) self.env = env or os.environ @property def service_url(self) -> str: """Gets the url of the Service.""" return f"http://{utils.join_host_port('localhost', self.port)}"
[docs] @abstractmethod def command_line_args(self) -> typing.List[str]: """A List of program arguments (excluding the executable).""" raise NotImplementedError("This method needs to be implemented in a sub class")
@property def path(self) -> str: return self._path @path.setter def path(self, value: str) -> None: self._path = str(value)
[docs] def start(self) -> None: """Starts the Service. :Exceptions: - WebDriverException : Raised either when it can't start the service or when it can't connect to the service """ self._start_process(self._path) count = 0 while True: self.assert_process_still_running() if self.is_connectable(): break # sleep increasing: 0.01, 0.06, 0.11, 0.16, 0.21, 0.26, 0.31, 0.36, 0.41, 0.46, 0.5 sleep(min(0.01 + 0.05 * count, 0.5)) count += 1 if count == 70: raise WebDriverException(f"Can not connect to the Service {self._path}")
[docs] def assert_process_still_running(self) -> None: """Check if the underlying process is still running.""" return_code = self.process.poll() if return_code: raise WebDriverException(f"Service {self._path} unexpectedly exited. Status code was: {return_code}")
[docs] def is_connectable(self) -> bool: """Establishes a socket connection to determine if the service running on the port is accessible.""" return utils.is_connectable(self.port)
[docs] def send_remote_shutdown_command(self) -> None: """Dispatch an HTTP request to the shutdown endpoint for the service in an attempt to stop it.""" try: request.urlopen(f"{self.service_url}/shutdown") except URLError: return for _ in range(30): if not self.is_connectable(): break sleep(1)
[docs] def stop(self) -> None: """Stops the service.""" if self.log_output not in {PIPE, subprocess.DEVNULL}: if isinstance(self.log_output, IOBase): self.log_output.close() elif isinstance(self.log_output, int): os.close(self.log_output) if self.process is not None: try: self.send_remote_shutdown_command() except TypeError: pass self._terminate_process()
def _terminate_process(self) -> None: """Terminate the child process. On POSIX this attempts a graceful SIGTERM followed by a SIGKILL, on a Windows OS kill is an alias to terminate. Terminating does not raise itself if something has gone wrong but (currently) silently ignores errors here. """ try: stdin, stdout, stderr = ( self.process.stdin, self.process.stdout, self.process.stderr, ) for stream in stdin, stdout, stderr: try: stream.close() # type: ignore except AttributeError: pass self.process.terminate() try: self.process.wait(60) except subprocess.TimeoutExpired: logger.error( "Service process refused to terminate gracefully with SIGTERM, escalating to SIGKILL.", exc_info=True, ) self.process.kill() except OSError: logger.error("Error terminating service process.", exc_info=True) def __del__(self) -> None: # `subprocess.Popen` doesn't send signal on `__del__`; # so we attempt to close the launched process when `__del__` # is triggered. # do not use globals here; interpreter shutdown may have already cleaned them up # and they would be `None`. This goes for anything this method is referencing internally. try: self.stop() except Exception: pass def _start_process(self, path: str) -> None: """Creates a subprocess by executing the command provided. :param cmd: full command to execute """ cmd = [path] cmd.extend(self.command_line_args()) close_file_descriptors = self.popen_kw.pop("close_fds", system() != "Windows") try: start_info = None if system() == "Windows": start_info = subprocess.STARTUPINFO() start_info.dwFlags = subprocess.CREATE_NEW_CONSOLE | subprocess.STARTF_USESHOWWINDOW start_info.wShowWindow = subprocess.SW_HIDE self.process = subprocess.Popen( cmd, env=self.env, close_fds=close_file_descriptors, stdout=self.log_output, stderr=self.log_output, stdin=PIPE, creationflags=self.creation_flags, startupinfo=start_info, **self.popen_kw, ) logger.debug( "Started executable: `%s` in a child process with pid: %s using %s to output %s", self._path,, self.creation_flags, self.log_output, ) except TypeError: raise except OSError as err: if err.errno == errno.EACCES: raise WebDriverException( f"'{os.path.basename(self._path)}' executable may have wrong permissions." ) from err raise