#!/usr/bin/env python
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"""Base class with common routines between the Apache, Lighttpd, and websocket servers."""

import errno
import logging
import socket
import sys
import tempfile
import time


_log = logging.getLogger(__name__)


class ServerError(Exception):
    pass


class HttpServerBase(object):
    """A skeleton class for starting and stopping servers used by the layout tests."""

    def __init__(self, port_obj):
        self._executive = port_obj._executive
        self._filesystem = port_obj._filesystem
        self._name = '<virtual>'
        self._mappings = {}
        self._pid = None
        self._pid_file = None
        self._port_obj = port_obj

        # We need a non-checkout-dependent place to put lock files, etc. We
        # don't use the Python default on the Mac because it defaults to a
        # randomly-generated directory under /var/folders and no one would ever
        # look there.
        tmpdir = tempfile.gettempdir()
        if sys.platform == 'darwin':
            tmpdir = '/tmp'

        self._runtime_path = self._filesystem.join(tmpdir, "WebKit")
        port_obj.maybe_make_directory(self._runtime_path)

    def start(self):
        """Starts the server. It is an error to start an already started server.

        This method also stops any stale servers started by a previous instance."""
        assert not self._pid, '%s server is already running' % self._name

        # Stop any stale servers left over from previous instances.
        if self._filesystem.exists(self._pid_file):
            self._pid = int(self._filesystem.read_text_file(self._pid_file))
            self._stop_running_server()
            self._pid = None

        self._remove_stale_logs()
        self._prepare_config()
        self._check_that_all_ports_are_available()

        self._pid = self._spawn_process()

        if self._wait_for_action(self._is_server_running_on_all_ports):
            _log.debug("%s successfully started (pid = %d)" % (self._name, self._pid))
        else:
            self._stop_running_server()
            raise ServerError('Failed to start %s server' % self._name)

    def stop(self):
        """Stops the server. Stopping a server that isn't started is harmless."""
        actual_pid = None
        if self._filesystem.exists(self._pid_file):
            actual_pid = int(self._filesystem.read_text_file(self._pid_file))
            if not self._pid:
                self._pid = actual_pid

        if not self._pid:
            return

        if not actual_pid:
            _log.warning('Failed to stop %s: pid file is missing' % self._name)
            return
        if self._pid != actual_pid:
            _log.warning('Failed to stop %s: pid file contains %d, not %d' %
                         (self._name, actual_pid, self._pid))
            # Try to kill the existing pid, anyway, in case it got orphaned.
            self._executive.kill_process(self._pid)
            self._pid = None
            return

        _log.debug("Attempting to shut down %s server at pid %d" % (self._name, self._pid))
        self._stop_running_server()
        _log.debug("%s server at pid %d stopped" % (self._name, self._pid))
        self._pid = None

    def _prepare_config(self):
        """This routine can be overridden by subclasses to do any sort
        of initialization required prior to starting the server that may fail."""
        pass

    def _remove_stale_logs(self):
        """This routine can be overridden by subclasses to try and remove logs
        left over from a prior run. This routine should log warnings if the
        files cannot be deleted, but should not fail unless failure to
        delete the logs will actually cause start() to fail."""
        pass

    def _spawn_process(self):
        """This routine must be implemented by subclasses to actually start the server.

        This routine returns the pid of the started process, and also ensures that that
        pid has been written to self._pid_file."""
        raise NotImplementedError()

    def _stop_running_server(self):
        """This routine must be implemented by subclasses to actually stop the running server listed in self._pid_file."""
        raise NotImplementedError()

    # Utility routines.

    def _remove_log_files(self, folder, starts_with):
        files = self._filesystem.listdir(folder)
        for file in files:
            if file.startswith(starts_with):
                full_path = self._filesystem.join(folder, file)
                self._filesystem.remove(full_path)

    def _wait_for_action(self, action, wait_secs=20.0, sleep_secs=1.0):
        """Repeat the action for wait_sec or until it succeeds, sleeping for sleep_secs
        in between each attempt. Returns whether it succeeded."""
        start_time = time.time()
        while time.time() - start_time < wait_secs:
            if action():
                return True
            _log.debug("Waiting for action: %s" % action)
            time.sleep(sleep_secs)

        return False

    def _is_server_running_on_all_ports(self):
        """Returns whether the server is running on all the desired ports."""
        if not self._executive.check_running_pid(self._pid):
            _log.debug("Server isn't running at all")
            raise ServerError("Server exited")

        for mapping in self._mappings:
            s = socket.socket()
            port = mapping['port']
            try:
                s.connect(('localhost', port))
                _log.debug("Server running on %d" % port)
            except socket.error, e:
                # this branch is needed on Mac 10.5 / python 2.5
                if e.args[0] not in (errno.ECONNREFUSED, errno.ECONNRESET):
                    raise
                _log.debug("Server NOT running on %d: %s" % (port, e))
                return False
            except IOError, e:
                if e.errno not in (errno.ECONNREFUSED, errno.ECONNRESET):
                    raise
                _log.debug("Server NOT running on %d: %s" % (port, e))
                return False
            finally:
                s.close()
        return True

    def _check_that_all_ports_are_available(self):
        for mapping in self._mappings:
            s = socket.socket()
            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            port = mapping['port']
            try:
                s.bind(('localhost', port))
            except IOError, e:
                if e.errno in (errno.EALREADY, errno.EADDRINUSE):
                    raise ServerError('Port %d is already in use.' % port)
                elif sys.platform == 'win32' and e.errno in (errno.WSAEACCES,):
                    raise ServerError('Port %d is already in use.' % port)
                else:
                    raise
            finally:
                s.close()
