#!/usr/bin/env python # Copyright (c) 2012 The Chromium Authors. All rights reserved. # Use of this source code is governed by a BSD-style license that can be # found in the LICENSE file. """Start and stop Web Page Replay. Of the public module names, the following one is key: ReplayServer: a class to start/stop Web Page Replay. """ import logging import os import re import signal import subprocess import sys import time import urllib _CHROME_SRC_DIR = os.path.abspath(os.path.join( os.path.dirname(__file__), os.pardir, os.pardir, os.pardir)) REPLAY_DIR = os.path.join( _CHROME_SRC_DIR, 'third_party', 'webpagereplay') LOG_PATH = os.path.join( _CHROME_SRC_DIR, 'webpagereplay_logs', 'logs.txt') # Chrome options to make it work with Web Page Replay. def GetChromeFlags(replay_host, http_port, https_port): assert replay_host and http_port and https_port, 'All arguments required' return [ '--host-resolver-rules=MAP * %s,EXCLUDE localhost' % replay_host, '--testing-fixed-http-port=%s' % http_port, '--testing-fixed-https-port=%s' % https_port, '--ignore-certificate-errors', ] # Signal masks on Linux are inherited from parent processes. If anything # invoking us accidentally masks SIGINT (e.g. by putting a process in the # background from a shell script), sending a SIGINT to the child will fail # to terminate it. Running this signal handler before execing should fix that # problem. def ResetInterruptHandler(): signal.signal(signal.SIGINT, signal.SIG_DFL) class ReplayError(Exception): """Catch-all exception for the module.""" pass class ReplayNotFoundError(ReplayError): def __init__(self, label, path): self.args = (label, path) def __str__(self): label, path = self.args return 'Path does not exist for %s: %s' % (label, path) class ReplayNotStartedError(ReplayError): pass class ReplayServer(object): """Start and Stop Web Page Replay. Web Page Replay is a proxy that can record and "replay" web pages with simulated network characteristics -- without having to edit the pages by hand. With WPR, tests can use "real" web content, and catch performance issues that may result from introducing network delays and bandwidth throttling. Example: with ReplayServer(archive_path): self.NavigateToURL(start_url) self.WaitUntil(...) Environment Variables (for development): WPR_ARCHIVE_PATH: path to alternate archive file (e.g. '/tmp/foo.wpr'). WPR_RECORD: if set, puts Web Page Replay in record mode instead of replay. WPR_REPLAY_DIR: path to alternate Web Page Replay source. """ def __init__(self, archive_path, replay_host, http_port, https_port, replay_options=None, replay_dir=None, log_path=None): """Initialize ReplayServer. Args: archive_path: a path to a specific WPR archive (required). replay_host: the hostname to serve traffic. http_port: an integer port on which to serve HTTP traffic. May be zero to let the OS choose an available port. https_port: an integer port on which to serve HTTPS traffic. May be zero to let the OS choose an available port. replay_options: an iterable of options strings to forward to replay.py. replay_dir: directory that has replay.py and related modules. log_path: a path to a log file. """ self.archive_path = os.environ.get('WPR_ARCHIVE_PATH', archive_path) self.replay_options = list(replay_options or ()) self.replay_dir = os.environ.get('WPR_REPLAY_DIR', replay_dir or REPLAY_DIR) self.log_path = log_path or LOG_PATH self.http_port = http_port self.https_port = https_port self._replay_host = replay_host if 'WPR_RECORD' in os.environ and '--record' not in self.replay_options: self.replay_options.append('--record') self.is_record_mode = '--record' in self.replay_options self._AddDefaultReplayOptions() self.replay_py = os.path.join(self.replay_dir, 'replay.py') if self.is_record_mode: self._CheckPath('archive directory', os.path.dirname(self.archive_path)) elif not os.path.exists(self.archive_path): self._CheckPath('archive file', self.archive_path) self._CheckPath('replay script', self.replay_py) self.log_fh = None self.replay_process = None def _AddDefaultReplayOptions(self): """Set WPR command-line options. Can be overridden if needed.""" self.replay_options = [ '--host', str(self._replay_host), '--port', str(self.http_port), '--ssl_port', str(self.https_port), '--use_closest_match', '--no-dns_forwarding', '--log_level', 'warning' ] + self.replay_options def _CheckPath(self, label, path): if not os.path.exists(path): raise ReplayNotFoundError(label, path) def _OpenLogFile(self): log_dir = os.path.dirname(self.log_path) if not os.path.exists(log_dir): os.makedirs(log_dir) return open(self.log_path, 'w') def WaitForStart(self, timeout): """Checks to see if the server is up and running.""" port_re = re.compile( '.*(?PHTTPS?) server started on (?P.*):(?P\d+)') start_time = time.time() elapsed_time = 0 while elapsed_time < timeout: if self.replay_process.poll() is not None: break # The process has exited. # Read the ports from the WPR log. if not self.http_port or not self.https_port: for line in open(self.log_path).readlines(): m = port_re.match(line.strip()) if m: if not self.http_port and m.group('protocol') == 'HTTP': self.http_port = int(m.group('port')) elif not self.https_port and m.group('protocol') == 'HTTPS': self.https_port = int(m.group('port')) # Try to connect to the WPR ports. if self.http_port and self.https_port: try: up_url = '%s://%s:%s/web-page-replay-generate-200' http_up_url = up_url % ('http', self._replay_host, self.http_port) https_up_url = up_url % ('https', self._replay_host, self.https_port) if (200 == urllib.urlopen(http_up_url, None, {}).getcode() and 200 == urllib.urlopen(https_up_url, None, {}).getcode()): return True except IOError: pass poll_interval = min(max(elapsed_time / 10., .1), 5) time.sleep(poll_interval) elapsed_time = time.time() - start_time return False def StartServer(self): """Start Web Page Replay and verify that it started. Raises: ReplayNotStartedError: if Replay start-up fails. """ cmd_line = [sys.executable, self.replay_py] cmd_line.extend(self.replay_options) cmd_line.append(self.archive_path) self.log_fh = self._OpenLogFile() logging.debug('Starting Web-Page-Replay: %s', cmd_line) kwargs = {'stdout': self.log_fh, 'stderr': subprocess.STDOUT} if sys.platform.startswith('linux') or sys.platform == 'darwin': kwargs['preexec_fn'] = ResetInterruptHandler self.replay_process = subprocess.Popen(cmd_line, **kwargs) if not self.WaitForStart(30): log = open(self.log_path).read() raise ReplayNotStartedError( 'Web Page Replay failed to start. Log output:\n%s' % log) def StopServer(self): """Stop Web Page Replay.""" if self.replay_process: logging.debug('Trying to stop Web-Page-Replay gracefully') try: url = 'http://localhost:%s/web-page-replay-command-exit' urllib.urlopen(url % self.http_port, None, {}) except IOError: # IOError is possible because the server might exit without response. pass start_time = time.time() while time.time() - start_time < 10: # Timeout after 10 seconds. if self.replay_process.poll() is not None: break time.sleep(1) else: try: # Use a SIGINT so that it can do graceful cleanup. self.replay_process.send_signal(signal.SIGINT) except: # pylint: disable=W0702 # On Windows, we are left with no other option than terminate(). if 'no-dns_forwarding' not in self.replay_options: logging.warning('DNS configuration might not be restored!') try: self.replay_process.terminate() except: # pylint: disable=W0702 pass self.replay_process.wait() if self.log_fh: self.log_fh.close() def __enter__(self): """Add support for with-statement.""" self.StartServer() return self def __exit__(self, unused_exc_type, unused_exc_val, unused_exc_tb): """Add support for with-statement.""" self.StopServer()