"""Base class for implementing servers"""
# Copyright (c) 2009-2012 Denis Bilenko. See LICENSE for details.
import sys
import _socket
import errno
from gevent.greenlet import Greenlet, getfuncname
from gevent.event import Event
from gevent.hub import string_types, integer_types, get_hub
__all__ = ['BaseServer']
class BaseServer(object):
"""An abstract base class that implements some common functionality for the servers in gevent.
*listener* can either be an address that the server should bind on or a :class:`gevent.socket.socket`
instance that is already bound (and put into listening mode in case of TCP socket).
*spawn*, if provided, is called to create a new greenlet to run the handler. By default, :func:`gevent.spawn` is used.
Possible values for *spawn*:
* a :class:`gevent.pool.Pool` instance -- *handle* will be executed
using :meth:`Pool.spawn` method only if the pool is not full.
While it is full, all the connection are dropped;
* :func:`gevent.spawn_raw` -- *handle* will be executed in a raw
greenlet which have a little less overhead then :class:`gevent.Greenlet` instances spawned by default;
* ``None`` -- *handle* will be executed right away, in the :class:`Hub` greenlet.
*handle* cannot use any blocking functions as it means switching to the :class:`Hub`.
* an integer -- a shortcut for ``gevent.pool.Pool(integer)``
"""
# the number of seconds to sleep in case there was an error in accept() call
# for consecutive errors the delay will double until it reaches max_delay
# when accept() finally succeeds the delay will be reset to min_delay again
min_delay = 0.01
max_delay = 1
# Sets the maximum number of consecutive accepts that a process may perform on
# a single wake up. High values give higher priority to high connection rates,
# while lower values give higher priority to already established connections.
# Default is 100. Note, that in case of multiple working processes on the same
# listening value, it should be set to a lower value. (pywsgi.WSGIServer sets it
# to 1 when environ["wsgi.multiprocess"] is true)
max_accept = 100
_spawn = Greenlet.spawn
# the default timeout that we wait for the client connections to close in stop()
stop_timeout = 1
fatal_errors = (errno.EBADF, errno.EINVAL, errno.ENOTSOCK)
def __init__(self, listener, handle=None, spawn='default'):
self._stop_event = Event()
self._stop_event.set()
self._watcher = None
self._timer = None
self.pool = None
try:
self.set_listener(listener)
self.set_spawn(spawn)
self.set_handle(handle)
self.delay = self.min_delay
self.loop = get_hub().loop
if self.max_accept < 1:
raise ValueError('max_accept must be positive int: %r' % (self.max_accept, ))
except:
self.close()
raise
def set_listener(self, listener):
if hasattr(listener, 'accept'):
if hasattr(listener, 'do_handshake'):
raise TypeError('Expected a regular socket, not SSLSocket: %r' % (listener, ))
self.family = listener.family
self.address = listener.getsockname()
self.socket = listener
else:
self.family, self.address = parse_address(listener)
def set_spawn(self, spawn):
if spawn == 'default':
self.pool = None
self._spawn = self._spawn
elif hasattr(spawn, 'spawn'):
self.pool = spawn
self._spawn = spawn.spawn
elif isinstance(spawn, (int, long)):
from gevent.pool import Pool
self.pool = Pool(spawn)
self._spawn = self.pool.spawn
else:
self.pool = None
self._spawn = spawn
if hasattr(self.pool, 'full'):
self.full = self.pool.full
if self.pool is not None:
self.pool._semaphore.rawlink(self._start_accepting_if_started)
def set_handle(self, handle):
if handle is not None:
self.handle = handle
if hasattr(self, 'handle'):
self._handle = self.handle
else:
raise TypeError("'handle' must be provided")
def _start_accepting_if_started(self, _event=None):
if self.started:
self.start_accepting()
def start_accepting(self):
if self._watcher is None:
# just stop watcher without creating a new one?
self._watcher = self.loop.io(self.socket.fileno(), 1)
self._watcher.start(self._do_read)
def stop_accepting(self):
if self._watcher is not None:
self._watcher.stop()
self._watcher = None
if self._timer is not None:
self._timer.stop()
self._timer = None
def do_handle(self, *args):
spawn = self._spawn
if spawn is None:
self._handle(*args)
else:
spawn(self._handle, *args)
def _do_read(self):
for _ in xrange(self.max_accept):
if self.full():
self.stop_accepting()
return
try:
args = self.do_read()
self.delay = self.min_delay
if not args:
return
except:
self.loop.handle_error(self, *sys.exc_info())
ex = sys.exc_info()[1]
if self.is_fatal_error(ex):
self.close()
sys.stderr.write('ERROR: %s failed with %s\n' % (self, str(ex) or repr(ex)))
return
if self.delay >= 0:
self.stop_accepting()
self._timer = self.loop.timer(self.delay)
self._timer.start(self._start_accepting_if_started)
self.delay = min(self.max_delay, self.delay * 2)
break
else:
try:
self.do_handle(*args)
except:
self.loop.handle_error((args[1:], self), *sys.exc_info())
if self.delay >= 0:
self.stop_accepting()
self._timer = self.loop.timer(self.delay)
self._timer.start(self._start_accepting_if_started)
self.delay = min(self.max_delay, self.delay * 2)
break
def full(self):
return False
def __repr__(self):
return '<%s at %s %s>' % (type(self).__name__, hex(id(self)), self._formatinfo())
def __str__(self):
return '<%s %s>' % (type(self).__name__, self._formatinfo())
def _formatinfo(self):
if hasattr(self, 'socket'):
try:
fileno = self.socket.fileno()
except Exception:
ex = sys.exc_info()[1]
fileno = str(ex)
result = 'fileno=%s ' % fileno
else:
result = ''
try:
if isinstance(self.address, tuple) and len(self.address) == 2:
result += 'address=%s:%s' % self.address
else:
result += 'address=%s' % (self.address, )
except Exception:
ex = sys.exc_info()[1]
result += str(ex) or '<error>'
try:
handle = getfuncname(self.__dict__['handle'])
except Exception:
handle = None
if handle is not None:
result += ' handle=' + handle
return result
@property
def server_host(self):
"""IP address that the server is bound to (string)."""
if isinstance(self.address, tuple):
return self.address[0]
@property
def server_port(self):
"""Port that the server is bound to (an integer)."""
if isinstance(self.address, tuple):
return self.address[1]
def init_socket(self):
"""If the user initialized the server with an address rather than socket,
then this function will create a socket, bind it and put it into listening mode.
It is not supposed to be called by the user, it is called by :meth:`start` before starting
the accept loop."""
pass
@property
def started(self):
return not self._stop_event.is_set()
def start(self):
"""Start accepting the connections.
If an address was provided in the constructor, then also create a socket,
bind it and put it into the listening mode.
"""
self.init_socket()
self._stop_event.clear()
try:
self.start_accepting()
except:
self.close()
raise
def close(self):
"""Close the listener socket and stop accepting."""
self._stop_event.set()
try:
self.stop_accepting()
finally:
try:
self.socket.close()
except Exception:
pass
finally:
self.__dict__.pop('socket', None)
self.__dict__.pop('handle', None)
self.__dict__.pop('_handle', None)
self.__dict__.pop('_spawn', None)
self.__dict__.pop('full', None)
if self.pool is not None:
self.pool._semaphore.unlink(self._start_accepting_if_started)
@property
def closed(self):
return not hasattr(self, 'socket')
def stop(self, timeout=None):
"""Stop accepting the connections and close the listening socket.
If the server uses a pool to spawn the requests, then :meth:`stop` also waits
for all the handlers to exit. If there are still handlers executing after *timeout*
has expired (default 1 second), then the currently running handlers in the pool are killed."""
self.close()
if timeout is None:
timeout = self.stop_timeout
if self.pool:
self.pool.join(timeout=timeout)
self.pool.kill(block=True, timeout=1)
def serve_forever(self, stop_timeout=None):
"""Start the server if it hasn't been already started and wait until it's stopped."""
# add test that serve_forever exists on stop()
if not self.started:
self.start()
try:
self._stop_event.wait()
finally:
Greenlet.spawn(self.stop, timeout=stop_timeout).join()
def is_fatal_error(self, ex):
return isinstance(ex, _socket.error) and ex[0] in self.fatal_errors
def _extract_family(host):
if host.startswith('[') and host.endswith(']'):
host = host[1:-1]
return _socket.AF_INET6, host
return _socket.AF_INET, host
def _parse_address(address):
if isinstance(address, tuple):
if ':' in address[0]:
return _socket.AF_INET6, address
return _socket.AF_INET, address
elif isinstance(address, string_types):
if ':' in address:
host, port = address.rsplit(':', 1)
family, host = _extract_family(host)
if host == '*':
host = ''
return family, (host, int(port))
else:
return _socket.AF_INET, ('', int(address))
elif isinstance(address, integer_types):
return _socket.AF_INET, ('', int(address))
else:
raise TypeError('Expected tuple or string, got %s' % type(address))
def parse_address(address):
try:
return _parse_address(address)
except ValueError:
raise ValueError('Failed to parse address %r: %s' % (address, sys.exc_info()[1]))