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305 lines
11 KiB
Python
305 lines
11 KiB
Python
"""
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This module implements functionality required by master processes, such as
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starting new contexts via SSH. Its size is also restricted, since it must be
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sent to any context that will be used to establish additional child contexts.
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"""
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import commands
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import getpass
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import inspect
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import logging
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import os
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import pkgutil
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import re
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import socket
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import sys
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import textwrap
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import types
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import zlib
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import econtext.core
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LOG = logging.getLogger('econtext')
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IOLOG = logging.getLogger('econtext.io')
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RLOG = logging.getLogger('econtext.ctx')
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DOCSTRING_RE = re.compile(r'""".+?"""', re.M | re.S)
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COMMENT_RE = re.compile(r'^\s*#.*$', re.M)
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def minimize_source(source):
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"""Remove comments and docstrings from Python `source`, preserving line
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numbers and syntax of empty blocks."""
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subber = lambda match: '""' + ('\n' * match.group(0).count('\n'))
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source = DOCSTRING_RE.sub(subber, source)
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source = COMMENT_RE.sub('\n', source)
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return source.replace(' ', '\t')
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def get_child_modules(module, prefix):
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"""Return the canonical names of all submodules of a package `module`."""
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it = pkgutil.iter_modules(module.__path__, prefix)
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return [name for _, name, _ in it]
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def create_child(*args):
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"""Create a child process whose stdin/stdout is connected to a socket,
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returning `(pid, socket_obj)`."""
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parentfp, childfp = socket.socketpair()
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pid = os.fork()
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if not pid:
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os.dup2(childfp.fileno(), 0)
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os.dup2(childfp.fileno(), 1)
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childfp.close()
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parentfp.close()
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os.execvp(args[0], args)
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raise SystemExit
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childfp.close()
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LOG.debug('create_child() child %d fd %d, parent %d, args %r',
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pid, parentfp.fileno(), os.getpid(), args)
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return pid, parentfp
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class Listener(econtext.core.BasicStream):
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def __init__(self, broker, address=None, backlog=30):
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self._broker = broker
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self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self._sock.bind(address or ('0.0.0.0', 0))
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self._sock.listen(backlog)
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econtext.core.set_cloexec(self._sock.fileno())
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self._listen_addr = self._sock.getsockname()
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self.read_side = econtext.core.Side(self, self._sock.fileno())
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broker.update_stream(self)
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def on_receive(self):
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sock, addr = self._sock.accept()
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context = Context(self._broker, name=addr)
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stream = econtext.core.Stream(context)
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stream.accept(sock.fileno(), sock.fileno())
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class LogForwarder(object):
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def __init__(self, context):
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self._context = context
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self._context.add_handle_cb(self.forward_log,
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handle=econtext.core.FORWARD_LOG)
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name = '%s.%s' % (RLOG.name, self._context.name)
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self._log = logging.getLogger(name)
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def forward_log(self, data):
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if data == econtext.core._DEAD:
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return
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name, level, s = data
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self._log.log(level, '%s: %s', name, s)
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class ModuleResponder(object):
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def __init__(self, context):
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self._context = context
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self._context.add_handle_cb(self.get_module,
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handle=econtext.core.GET_MODULE)
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def get_module(self, data):
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if data == econtext.core._DEAD:
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return
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reply_to, fullname = data
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LOG.debug('get_module(%r, %r)', reply_to, fullname)
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try:
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module = __import__(fullname, {}, {}, [''])
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is_pkg = getattr(module, '__path__', None) is not None
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path = inspect.getsourcefile(module)
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try:
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source = inspect.getsource(module)
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except IOError:
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if not is_pkg:
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raise
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source = '\n'
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if is_pkg:
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prefix = module.__name__ + '.'
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present = get_child_modules(module, prefix)
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else:
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present = None
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compressed = zlib.compress(minimize_source(source))
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reply = (is_pkg, present, path, compressed)
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self._context.enqueue(reply_to, reply)
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except Exception:
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LOG.debug('While importing %r', fullname, exc_info=True)
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self._context.enqueue(reply_to, None)
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class LocalStream(econtext.core.Stream):
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"""
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Base for streams capable of starting new slaves.
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"""
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#: The path to the remote Python interpreter.
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python_path = 'python'
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def __init__(self, context):
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super(LocalStream, self).__init__(context)
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self._permitted_classes = set([('econtext.core', 'CallError')])
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def on_shutdown(self):
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"""Request the slave gracefully shut itself down."""
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LOG.debug('%r closing CALL_FUNCTION channel', self)
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self.enqueue(econtext.core.CALL_FUNCTION, econtext.core._DEAD)
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def _find_global(self, module_name, class_name):
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"""Return the class implementing `module_name.class_name` or raise
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`StreamError` if the module is not whitelisted."""
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if (module_name, class_name) not in self._permitted_classes:
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raise econtext.core.StreamError(
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'%r attempted to unpickle %r in module %r',
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self._context, class_name, module_name)
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return getattr(sys.modules[module_name], class_name)
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def allow_class(self, module_name, class_name):
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"""Add `module_name` to the list of permitted modules."""
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self._permitted_modules.add((module_name, class_name))
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# base64'd and passed to 'python -c'. It forks, dups 0->100, creates a
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# pipe, then execs a new interpreter with a custom argv. CONTEXT_NAME is
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# replaced with the context name. Optimized for size.
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def _first_stage():
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import os,sys,zlib
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R,W=os.pipe()
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if os.fork():
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os.dup2(0,100)
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os.dup2(R,0)
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os.close(R)
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os.close(W)
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os.execv(sys.executable,('econtext:'+CONTEXT_NAME,))
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else:
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os.fdopen(W,'wb',0).write(zlib.decompress(sys.stdin.read(input())))
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print 'OK'
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sys.exit(0)
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def get_boot_command(self):
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name = self._context.remote_name
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if name is None:
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name = '%s@%s:%d'
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name %= (getpass.getuser(), socket.gethostname(), os.getpid())
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source = inspect.getsource(self._first_stage)
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source = textwrap.dedent('\n'.join(source.strip().split('\n')[1:]))
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source = source.replace(' ', '\t')
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source = source.replace('CONTEXT_NAME', repr(name))
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encoded = source.encode('base64').replace('\n', '')
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return [self.python_path, '-c',
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'exec "%s".decode("base64")' % (encoded,)]
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def __repr__(self):
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return '%s(%s)' % (self.__class__.__name__, self._context)
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def get_preamble(self):
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source = inspect.getsource(econtext.core)
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source += '\nExternalContext().main%r\n' % ((
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self._context.key,
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LOG.level or logging.getLogger().level or logging.INFO,
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),)
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compressed = zlib.compress(minimize_source(source))
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return str(len(compressed)) + '\n' + compressed
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def connect(self):
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LOG.debug('%r.connect()', self)
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pid, sock = create_child(*self.get_boot_command())
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self.read_side = econtext.core.Side(self, os.dup(sock.fileno()))
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self.write_side = econtext.core.Side(self, os.dup(sock.fileno()))
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sock.close()
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LOG.debug('%r.connect(): child process stdin/stdout=%r',
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self, self.read_side.fd)
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econtext.core.write_all(self.write_side.fd, self.get_preamble())
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s = os.read(self.read_side.fd, 4096)
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if s != 'OK\n':
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raise econtext.core.StreamError('Bootstrap failed; stdout: %r', s)
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class SshStream(LocalStream):
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#: The path to the SSH binary.
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ssh_path = 'ssh'
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def get_boot_command(self):
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bits = [self.ssh_path]
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if self._context.username:
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bits += ['-l', self._context.username]
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bits.append(self._context.hostname)
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base = super(SshStream, self).get_boot_command()
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return bits + map(commands.mkarg, base)
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class Broker(econtext.core.Broker):
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#: Always allow time for slaves to drain.
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graceful_count = 1
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def create_listener(self, address=None, backlog=30):
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"""Listen on `address` for connections from newly spawned contexts."""
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self._listener = Listener(self, address, backlog)
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def get_local(self, name='default', python_path=None):
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"""Get the named context running on the local machine, creating it if
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it does not exist."""
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context = Context(self, name)
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context.stream = LocalStream(context)
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if python_path:
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context.stream.python_path = python_path
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context.stream.connect()
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return self.register(context)
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def get_remote(self, hostname, username=None, name=None, python_path=None):
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"""Get the named remote context, creating it if it does not exist."""
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if name is None:
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name = hostname
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context = Context(self, name, hostname, username)
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context.stream = SshStream(context)
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if python_path:
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context.stream.python_path = python_path
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context.stream.connect()
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return self.register(context)
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class Context(econtext.core.Context):
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def __init__(self, *args, **kwargs):
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super(Context, self).__init__(*args, **kwargs)
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self.responder = ModuleResponder(self)
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self.log_forwarder = LogForwarder(self)
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def on_disconnect(self):
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self.stream = None
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def call_with_deadline(self, deadline, with_context, fn, *args, **kwargs):
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"""Invoke `fn([context,] *args, **kwargs)` in the external context.
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If `with_context` is True, pass its
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:py:class:`econtext.core.ExternalContext` instance as first parameter.
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If `deadline` is not ``None``, expire the call after `deadline`
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seconds. If `deadline` is ``None``, the invocation may block
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indefinitely."""
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LOG.debug('%r.call_with_deadline(%r, %r, %r, *%r, **%r)',
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self, deadline, with_context, fn, args, kwargs)
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if isinstance(fn, types.MethodType) and \
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isinstance(fn.im_self, (type, types.ClassType)):
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klass = fn.im_self.__name__
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else:
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klass = None
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call = (with_context, fn.__module__, klass, fn.__name__, args, kwargs)
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result = self.enqueue_await_reply(econtext.core.CALL_FUNCTION,
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deadline, call)
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if isinstance(result, econtext.core.CallError):
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raise result
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return result
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def call(self, fn, *args, **kwargs):
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"""Invoke `fn(*args, **kwargs)` in the external context."""
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return self.call_with_deadline(None, False, fn, *args, **kwargs)
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