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mitogen/econtext.py

834 lines
25 KiB
Python

#!/usr/bin/env python2.5
'''
Python External Execution Contexts.
'''
import atexit
import cPickle
import cStringIO
import commands
import getpass
import hmac
import imp
import inspect
import os
import random
import select
import sha
import signal
import socket
import struct
import sys
import syslog
import textwrap
import threading
import traceback
import types
import zlib
#
# Module-level data.
#
GET_MODULE = 0L
CALL_FUNCTION = 1L
DEBUG = True
import sys
sys.stderr = open('milf1', 'w', 1)
#
# Exceptions.
#
class ContextError(Exception):
'Raised when a problem occurs with a context.'
def __init__(self, fmt, *args):
Exception.__init__(self, fmt % args)
class ChannelError(ContextError):
'Raised when a channel dies or has been closed.'
class StreamError(ContextError):
'Raised when a stream cannot be established.'
class CorruptMessageError(StreamError):
'Raised when a corrupt message is received on a stream.'
class TimeoutError(StreamError):
'Raised when a timeout occurs on a stream.'
#
# Helpers.
#
def Log(fmt, *args):
if DEBUG:
sys.stderr.write('%d (%d): %s\n' % (os.getpid(), os.getppid(),
(fmt % args).replace('econtext.', '')))
def write_all(fd, s):
written = 0
while written < len(s):
rc = os.write(fd, buffer(s, written))
if not rc:
raise IOError('short write')
written += rc
return written
def CreateChild(*args):
'''
Create a child process whose stdin/stdout is connected to a socket.
Args:
*args: executable name and process arguments.
Returns:
pid, sock
'''
parentfp, childfp = socket.socketpair()
pid = os.fork()
if not pid:
os.dup2(childfp.fileno(), 0)
os.dup2(childfp.fileno(), 1)
sys.stderr = open('milf2', 'w', 1)
childfp.close()
parentfp.close()
os.execvp(args[0], args)
raise SystemExit
childfp.close()
Log('CreateChild() child %d fd %d, parent %d, args %r',
pid, parentfp.fileno(), os.getpid(), args)
return pid, parentfp
class PartialFunction(object):
'''
Partial function implementation.
'''
def __init__(self, fn, *partial_args):
self.fn = fn
self.partial_args = partial_args
def __call__(self, *args, **kwargs):
return self.fn(*(self.partial_args+args), **kwargs)
def __repr__(self):
return 'PartialFunction(%r, *%r)' % (self.fn, self.partial_args)
class Channel(object):
def __init__(self, stream, handle):
self._stream = stream
self._handle = handle
self._wake_event = threading.Event()
self._queue_lock = threading.Lock()
self._queue = []
self._stream.AddHandleCB(self._InternalReceive, handle)
def _InternalReceive(self, killed, data):
'''
Callback from the stream object; appends a tuple of
(killed-or-closed, data) to the internal queue and wakes the internal
event.
Args:
# Has the Stream object lost its connection?
killed: bool
data: (
# Has the remote Channel had Close() called?
bool,
# The object passed to the remote Send()
object
)
'''
Log('%r._InternalReceive(%r, %r)', self, killed, data)
self._queue_lock.acquire()
try:
self._queue.append((killed or data[0], killed or data[1]))
self._wake_event.set()
finally:
self._queue_lock.release()
def Close(self):
'''
Indicate this channel is closed to the remote side.
'''
Log('%r.Close()', self)
self._stream.Enqueue(handle, (True, None))
def Send(self, data):
'''
Send the given object to the remote side.
'''
Log('%r.Send(%r)', self, data)
self._stream.Enqueue(handle, (False, data))
def Receive(self, timeout=None):
'''
Receive the next object to arrive on this channel, or return if the
optional timeout is reached.
Args:
timeout: float
Returns:
object
'''
Log('%r.Receive(%r)', self, timeout)
if not self._queue:
self._wake_event.wait(timeout)
if not self._wake_event.isSet():
return
self._queue_lock.acquire()
try:
self._wake_event.clear()
Log('%r.Receive() queue is %r', self, self._queue)
closed, data = self._queue.pop(0)
Log('%r.Receive() got closed=%r, data=%r', self, closed, data)
if closed:
raise ChannelError('Channel is closed.')
return data
finally:
self._queue_lock.release()
def __iter__(self):
'''
Return an iterator that yields objects arriving on this channel, until
the channel dies or is closed.
'''
while True:
try:
yield self.Receive()
except ChannelError:
return
def __repr__(self):
return 'econtext.Channel(%r, %r)' % (self._stream, self._handle)
class SlaveModuleImporter(object):
'''
Import protocol implementation that fetches modules from the parent
process.
'''
def __init__(self, context):
'''
Initialise a new instance.
Args:
context: Context instance this importer will communicate via.
'''
self._context = context
def find_module(self, fullname, path=None):
if not imp.find_module(fullname):
return self
def load_module(self, fullname):
kind, data = self._context.EnqueueAwaitReply(GET_MODULE, fullname)
def GetModule(cls, killed, fullname):
Log('%r.GetModule(%r, %r)', cls, killed, fullname)
if killed:
return
if fullname in sys.modules:
pass
GetModule = classmethod(GetModule)
#
# Stream implementations.
#
class Stream(object):
def __init__(self, context):
'''
Initialize a new Stream instance.
Args:
context: econtext.Context
'''
self._context = context
self._input_buf = self._output_buf = ''
self._input_buf_lock = threading.Lock()
self._output_buf_lock = threading.Lock()
self._rhmac = hmac.new(context.key, digestmod=sha.new)
self._whmac = self._rhmac.copy()
self._last_handle = 0
self._handle_map = {}
self._handle_lock = threading.Lock()
self._func_refs = {}
self._func_ref_lock = threading.Lock()
self._pickler_file = cStringIO.StringIO()
self._pickler = cPickle.Pickler(self._pickler_file)
self._pickler.persistent_id = self._CheckFunctionPerID
self._unpickler_file = cStringIO.StringIO()
self._unpickler = cPickle.Unpickler(self._unpickler_file)
self._unpickler.persistent_load = self._LoadFunctionFromPerID
def Pickle(self, obj):
'''
Serialize the given object using the pickler.
Args:
obj: object
Returns:
str
'''
self._pickler.dump(obj)
data = self._pickler_file.getvalue()
self._pickler_file.seek(0)
self._pickler_file.truncate(0)
return data
def Unpickle(self, data):
'''
Unserialize the given string using the unpickler.
Args:
data: str
Returns:
object
'''
Log('%r.Unpickle(%r)', self, data)
self._unpickler_file.write(data)
self._unpickler_file.seek(0)
data = self._unpickler.load()
self._unpickler_file.seek(0)
self._unpickler_file.truncate(0)
return data
def _CheckFunctionPerID(self, obj):
'''
Return None or a persistent ID for an object.
Please see the cPickle documentation.
Args:
obj: object
Returns:
str
'''
if isinstance(obj, (types.FunctionType, types.MethodType)):
pid = 'FUNC:' + repr(obj)
self._func_refs[per_id] = obj
return pid
def _LoadFunctionFromPerID(self, pid):
'''
Load an object from a persistent ID.
Please see the cPickle documentation.
Args:
pid: str
Returns:
object
'''
if not pid.startswith('FUNC:'):
raise CorruptMessageError('unrecognized persistent ID received: %r', pid)
return PartialFunction(self._CallPersistentWhatsit, pid)
def AllocHandle(self):
'''
Allocate a unique handle for this stream.
Returns:
long
'''
self._handle_lock.acquire()
try:
self._last_handle += 1L
finally:
self._handle_lock.release()
return self._last_handle
def AddHandleCB(self, fn, handle, persist=True):
'''
Invoke a function for all messages with the given handle.
Args:
fn: callable
handle: long
persist: False to only receive a single message.
'''
Log('%r.AddHandleCB(%r, %r, persist=%r)', self, fn, handle, persist)
self._handle_lock.acquire()
try:
self._handle_map[handle] = persist, fn
finally:
self._handle_lock.release()
def Receive(self):
'''
Handle the next complete message on the stream. Raise
CorruptMessageError or IOError on failure.
'''
Log('%r.Receive()', self)
self._input_buf += os.read(self._fd, 4096)
if len(self._input_buf) < 24:
return
msg_mac = self._input_buf[:20]
msg_len = struct.unpack('>L', self._input_buf[20:24])[0]
if len(self._input_buf) < msg_len-24:
return
self._rhmac.update(self._input_buf[20:msg_len+24])
expected_mac = self._rhmac.digest()
if msg_mac != expected_mac:
raise CorruptMessageError('%r got invalid MAC: expected %r, got %r',
self, msg_mac.encode('hex'),
expected_mac.encode('hex'))
try:
handle, data = self.Unpickle(self._input_buf[24:msg_len+24])
self._input_buf = self._input_buf[msg_len+4:]
handle = long(handle)
Log('%r.Receive(): decoded handle=%r; data=%r', self, handle, data)
persist, fn = self._handle_map[handle]
if not persist:
del self._handle_map[handle]
except KeyError, ex:
raise CorruptMessageError('%r got invalid handle: %r', self, handle)
except (TypeError, ValueError), ex:
raise CorruptMessageError('%r got invalid message: %s', self, ex)
fn(False, data)
def Transmit(self):
'''
Transmit buffered messages.
Returns:
bool: more data left in bufer?
Raises:
IOError
'''
Log('%r.Transmit()', self)
written = os.write(self._fd, self._output_buf[:4096])
self._output_buf = self._output_buf[written:]
return bool(self._output_buf)
def Enqueue(self, handle, obj):
'''
Serialize an object, send it to the given handle, and tell our context's
broker we have output.
Args:
handle: long
obj: object
'''
Log('%r.Enqueue(%r, %r)', self, handle, obj)
self._output_buf_lock.acquire()
try:
encoded = self.Pickle((handle, obj))
msg = struct.pack('>L', len(encoded)) + encoded
self._whmac.update(msg)
self._output_buf += self._whmac.digest() + msg
finally:
self._output_buf_lock.release()
self._context.broker.Register(self._context)
def Disconnect(self):
'''
Close our associated file descriptor and tell any registered callbacks
that the connection has been destroyed.
'''
Log('%r.Disconnect()', self)
try:
os.close(self._fd)
except OSError, e:
Log('%r.Disconnect(): did not close fd %s: %s', self, self._fd, e)
for handle, (persist, fn) in self._handle_map.iteritems():
Log('%r.Disconnect(): killing stale callback handle=%r; fn=%r',
self, handle, fn)
fn(True, None)
@classmethod
def Accept(cls, context, sock):
'''
'''
stream = cls(context)
stream.sock = sock
stream._fd = sock.fileno()
context.SetStream(stream)
context.broker.Register(context)
def Connect(self):
'''
Connect to a Broker at the address specified in our associated Context.
'''
Log('%r.Connect()', self)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._fd = sock.fileno()
sock.connect(self._context.parent_addr)
self.Enqueue(0, self._context.name)
def fileno(self):
return self._fd
def __repr__(self):
return 'econtext.%s(<context=%r>)' %\
(self.__class__.__name__, self._context)
class LocalStream(Stream):
'''
Base for streams capable of starting new slaves.
'''
python_path = property(
lambda self: getattr(self, '_python_path', sys.executable),
lambda self, path: setattr(self, '_python_path', path),
doc='The path to the remote Python interpreter.')
def __init__(self, context):
super(LocalStream, self).__init__(context)
self._permitted_modules = {}
self._unpickler.find_global = self._FindGlobal
self.AddHandleCB(SlaveModuleImporter.GetModule, handle=GET_MODULE)
def _FindGlobal(self, module_name, class_name):
'''
See the cPickle documentation: given a module and class name, determine
whether class referred to is safe for unpickling.
Args:
module_name: str
class_name: str
Returns:
classobj or type
'''
if module_name not in self._permitted_modules:
raise StreamError('context %r attempted to unpickle %r in module %r',
self._context, class_name, module_name)
return getattr(sys.modules[module_name], class_name)
def AllowModule(self, module_name):
'''
Add the given module to the list of permitted modules.
Args:
module_name: str
'''
self._permitted_modules.add(module_name)
# Hexed and passed to 'python -c'. It forks, dups 0->100, creates a pipe,
# then execs a new interpreter with a custom argv. CONTEXT_NAME is replaced
# with the context name. Optimized for source size.
def _FirstStage():
import os,sys,zlib
R,W=os.pipe()
if os.fork():
os.dup2(0,100)
os.dup2(R,0)
os.close(R)
os.close(W)
os.execv(sys.executable,(CONTEXT_NAME,))
else:
os.fdopen(W,'wb',0).write(zlib.decompress(sys.stdin.read(input())))
print 'OK'
sys.exit(0)
def GetBootCommand(self):
source = inspect.getsource(self._FirstStage)
source = textwrap.dedent('\n'.join(source.strip().split('\n')[1:]))
source = source.replace(' ', '\t')
source = source.replace('CONTEXT_NAME', repr(self._context.name))
return [self.python_path, '-c',
'exec "%s".decode("hex")' % (source.encode('hex'),)]
def __repr__(self):
return '%s(%s)' % (self.__class__.__name__, self._context)
def Connect(self):
Log('%r.Connect()', self)
pid, sock = CreateChild(*self.GetBootCommand())
self._fd = os.dup(sock.fileno())
sock.close()
Log('%r.Connect(): child process stdin/stdout=%r', self, self._fd)
source = inspect.getsource(sys.modules[__name__])
source += '\nExternalContextMain(%r, %r, %r)\n' %\
(self._context.name, self._context.broker._listen_addr,
self._context.key)
compressed = zlib.compress(source)
preamble = str(len(compressed)) + '\n' + compressed
write_all(self._fd, preamble)
assert os.read(self._fd, 3) == 'OK\n'
class SSHStream(LocalStream):
ssh_path = property(
lambda self: getattr(self, '_ssh_path', 'ssh'),
lambda self, path: setattr(self, '_ssh_path', path),
doc='The path to the SSH binary.')
def GetBootCommand(self):
bits = [self.ssh_path]
if self._context.username:
bits += ['-l', self._context.username]
bits.append(self._context.hostname)
return bits + map(commands.mkarg, super(SSHStream, self).GetBootCommand())
class Context(object):
'''
Represents a remote context regardless of connection method.
'''
def __init__(self, broker, name=None, hostname=None, username=None, key=None,
parent_addr=None):
self.broker = broker
self.name = name
self.hostname = hostname
self.username = username
self.parent_addr = parent_addr
self.key = key or ('%016x' % random.getrandbits(128))
def GetStream(self):
return self._stream
def SetStream(self, stream):
self._stream = stream
return stream
def EnqueueAwaitReply(self, handle, deadline, data):
'''
Send a message to the given handle and wait for a response with an
optional timeout. The message contains (reply_handle, data), where
reply_handle is the handle on which this function expects its reply.
'''
Log('%r.EnqueueAwaitReply(%r, %r, %r)', self, handle, deadline, data)
reply_handle = self._stream.AllocHandle()
reply_event = threading.Event()
container = []
def _Receive(killed, data):
Log('%r._Receive(%r, %r)', self, killed, data)
container.extend([killed, data])
reply_event.set()
self._stream.AddHandleCB(_Receive, reply_handle, persist=False)
self._stream.Enqueue(CALL_FUNCTION, (False, (reply_handle,) + data))
reply_event.wait(deadline)
if not reply_event.isSet():
self.Disconnect()
raise TimeoutError('deadline exceeded.')
killed, data = container
if killed:
raise StreamError('lost connection during call.')
Log('%r._EnqueueAwaitReply(): got reply: %r', self, data)
return data
def CallWithDeadline(self, fn, deadline, *args, **kwargs):
Log('%r.CallWithDeadline(%r, %r, *%r, **%r)', self, fn, deadline, args,
kwargs)
use_channel = bool(kwargs.pop('use_channel', False))
if isinstance(fn, types.MethodType) and \
isinstance(fn.im_self, (type, types.ClassType)):
fn_class = fn.im_self.__name__
else:
fn_class = None
call = (use_channel, fn.__module__, fn_class, fn.__name__, args, kwargs)
success, result = self.EnqueueAwaitReply(CALL_FUNCTION, deadline, call)
if success:
return result
else:
exc_obj, traceback = result
exc_obj.real_traceback = traceback
raise exc_obj
def Call(self, fn, *args, **kwargs):
return self.CallWithDeadline(fn, None, *args, **kwargs)
def __repr__(self):
bits = map(repr, filter(None, [self.name, self.hostname, self.username]))
return 'Context(%s)' % ', '.join(bits)
class Broker(object):
'''
Context broker: this is responsible for keeping track of contexts, any
stream that is associated with them, and for I/O multiplexing.
'''
def __init__(self):
self._dead = False
self._poller = select.poll()
self._poller_fd_map = {}
self._poller_lock = threading.Lock()
self._contexts = {}
self._wake_rfd, self._wake_wfd = os.pipe()
self._listen_sock = None
self._poller.register(self._wake_rfd)
self._thread = threading.Thread(target=self.Loop, name='Broker')
self._thread.setDaemon(True)
self._thread.start()
def CreateListener(self, address=None, backlog=30):
'''
Create a socket to accept connections from newly spawned contexts.
Args:
address: The IPv4 address tuple to listen on.
backlog: Number of connections to accept while broker thread is busy.
'''
self._listen_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._listen_sock.bind(address or ('0.0.0.0', 0))
self._listen_sock.listen(backlog)
self._listen_addr = self._listen_sock.getsockname()
self._poller.register(self._listen_sock)
def Register(self, context):
'''
Put a context under control of this broker.
'''
Log('%r.Register(%r) -> fd=%r', self, context, context.GetStream().fileno())
self._poller_lock.acquire()
os.write(self._wake_wfd, ' ')
try:
self._contexts[context.name] = context
self._poller.register(context.GetStream())
self._poller_fd_map[context.GetStream().fileno()] = context.GetStream()
finally:
self._poller_lock.release()
return context
def GetLocal(self, name):
'''
Return the named local context, or create it if it doesn't exist.
Args:
name: 'my-local-context'
Returns:
econtext.Context
'''
context = Context(self, name)
context.SetStream(LocalStream(context)).Connect()
return self.Register(context)
def GetRemote(self, hostname, username, name=None):
'''
Return the named remote context, or create it if it doesn't exist.
'''
if name is None:
name = 'econtext[%s@%s:%d]' %\
(username, os.getenv('HOSTNAME'), os.getpid())
context = Context(self, name, hostname, username)
context.SetStream(SSHStream(context)).Connect()
return self.Register(context)
def Loop(self):
'''
Handle stream events until Finalize() is called.
'''
while not self._dead:
Log('%r.Loop()', self)
self._poller_lock.acquire()
self._poller_lock.release()
for fd, event in self._poller.poll():
if fd == self._wake_rfd:
Log('%r: got event on wake_rfd=%d.', self, self._wake_rfd)
os.read(self._wake_rfd, 1)
continue
elif self._listen_sock and fd == self._listen_sock.fileno():
context = Context(self)
sock, addr = self._listen_sock.accept()
Stream.Accept(context, sock)
continue
obj = self._poller_fd_map[fd]
if event & select.POLLHUP:
Log('%r: POLLHUP for %d, %r', self, fd, obj)
obj.Disconnect()
elif event & select.POLLIN:
Log('%r: POLLIN for %d, %r', self, fd, obj)
obj.Receive()
elif event & select.POLLOUT:
Log('%r: POLLOUT for %d, %r', self, fd, obj)
if not obj.Transmit(): # If no output buffered, unset POLLOUT.
self._poller.unregister(obj)
self._poller.register(obj, select.POLLIN)
elif event & select.POLLNVAL:
Log('%r: POLLNVAL for %d, %r', self, fd, obj)
obj.Disconnect()
self._poller.unregister(obj)
def Finalize(self):
'''
Tell all active streams to disconnect.
'''
self._dead = True
self._poller_lock.acquire()
try:
for name, context in self._contexts.iteritems():
context.GetStream().Disconnect()
finally:
self._poller_lock.release()
def __repr__(self):
return 'econtext.Broker(<contexts=%s>)' % (self._contexts.keys(),)
def ExternalContextMain(context_name, parent_addr, key):
syslog.openlog('%s:%s' % (getpass.getuser(), context_name), syslog.LOG_PID)
syslog.syslog('initializing (parent=%s)' % (os.getenv('SSH_CLIENT'),))
Log('ExternalContextMain(%r, %r, %r)', context_name, parent_addr, key)
os.wait() # Reap the first stage.
os.dup2(100, 0)
os.close(100)
broker = Broker()
context = Context(broker, 'parent', parent_addr=parent_addr, key=key)
stream = context.SetStream(Stream(context))
stream.Connect()
broker.Register(context)
for call_info in Channel(stream, CALL_FUNCTION):
Log('ExternalContextMain(): CALL_FUNCTION %r', call_info)
reply_handle, mod_name, func_name, args, kwargs = call_info
fn = getattr(__import__(mod_name), func_name)
try:
stream.Enqueue(reply_handle, (True, fn(*args, **kwargs)))
except Exception, e:
stream.Enqueue(reply_handle, (False, (e, traceback.extract_stack())))