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609 lines
20 KiB
Python
609 lines
20 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 errno
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import getpass
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import imp
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import inspect
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import itertools
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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 select
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import socket
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import sys
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import textwrap
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import time
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import types
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import zlib
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if not hasattr(pkgutil, 'find_loader'):
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# find_loader() was new in >=2.5, but the modern pkgutil.py syntax has
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# been kept intentionally 2.3 compatible so we can reuse it.
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from econtext.compat import pkgutil
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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('ctx')
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DOCSTRING_RE = re.compile(r'""".+?"""', re.M | re.S)
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COMMENT_RE = re.compile(r'^[ ]*#[^\n]*$', re.M)
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IOLOG_RE = re.compile(r'^[ ]*IOLOG.debug\(.+?\)$', re.M)
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PERMITTED_CLASSES = set([
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('econtext.core', 'CallError'),
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('econtext.core', 'Dead'),
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])
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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('', source)
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return source.replace(' ', '\t')
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def get_child_modules(path, fullname):
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"""Return the canonical names of all submodules of a package `module`."""
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it = pkgutil.iter_modules([os.path.dirname(path)])
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return ['%s.%s' % (fullname, 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, os.dup(parentfp.fileno())
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def write_all(fd, s):
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written = 0
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while written < len(s):
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rc = os.write(fd, buffer(s, written))
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if not rc:
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raise IOError('short write')
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written += rc
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return written
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def read_with_deadline(fd, size, deadline):
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timeout = deadline - time.time()
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if timeout > 0:
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rfds, _, _ = select.select([fd], [], [], timeout)
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if rfds:
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return os.read(fd, size)
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raise econtext.core.TimeoutError('read timed out')
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def iter_read(fd, deadline):
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if deadline is not None:
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LOG.debug('Warning: iter_read(.., deadline=...) unimplemented')
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bits = []
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while True:
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s, disconnected = econtext.core.io_op(os.read, fd, 4096)
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if disconnected:
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s = ''
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if not s:
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raise econtext.core.StreamError(
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'EOF on stream; last 100 bytes received: %r' %
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(''.join(bits)[-100:],)
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)
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bits.append(s)
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yield s
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def discard_until(fd, s, deadline):
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for buf in iter_read(fd, deadline):
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if buf.endswith(s):
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return
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class LogForwarder(object):
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def __init__(self, router):
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self._router = router
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self._cache = {}
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router.add_handler(self._on_forward_log, econtext.core.FORWARD_LOG)
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def _on_forward_log(self, msg):
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if msg == econtext.core._DEAD:
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return
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logger = self._cache.get(msg.src_id)
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if logger is None:
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context = self._router.context_by_id(msg.src_id)
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if context is None:
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LOG.error('FORWARD_LOG received from src_id %d', msg.src_id)
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return
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name = '%s.%s' % (RLOG.name, context.name)
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self._cache[msg.src_id] = logger = logging.getLogger(name)
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name, level_s, s = msg.data.split('\x00', 2)
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logger.log(int(level_s), '%s: %s', name, s)
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def __repr__(self):
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return 'LogForwarder(%r)' % (self._router,)
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class ModuleResponder(object):
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def __init__(self, router):
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self._router = router
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router.add_handler(self._on_get_module, econtext.core.GET_MODULE)
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def __repr__(self):
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return 'ModuleResponder(%r)' % (self._router,)
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def _get_module_via_pkgutil(self, fullname):
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"""Attempt to fetch source code via pkgutil. In an ideal world, this
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would be the only required implementation of get_module()."""
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loader = pkgutil.find_loader(fullname)
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LOG.debug('pkgutil.find_loader(%r) -> %r', fullname, loader)
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if not loader:
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return
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try:
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path = loader.get_filename(fullname)
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source = loader.get_source(fullname)
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if path is not None and source is not None:
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return path, source, loader.is_package(fullname)
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except AttributeError:
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return
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def _get_module_via_sys_modules(self, fullname):
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"""Attempt to fetch source code via sys.modules. This is specifically
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to support __main__, but it may catch a few more cases."""
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if fullname not in sys.modules:
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LOG.debug('%r does not appear in sys.modules', fullname)
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return
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is_pkg = hasattr(sys.modules[fullname], '__path__')
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try:
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source = inspect.getsource(sys.modules[fullname])
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except IOError:
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# Work around inspect.getsourcelines() bug.
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if not is_pkg:
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raise
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source = '\n'
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return (sys.modules[fullname].__file__.rstrip('co'),
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source,
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hasattr(sys.modules[fullname], '__path__'))
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def _get_module_via_parent_enumeration(self, fullname):
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"""Attempt to fetch source code by examining the module's (hopefully
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less insane) parent package. Required for ansible.compat.six."""
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pkgname, _, modname = fullname.rpartition('.')
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pkg = sys.modules.get(pkgname)
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if pkg is None or not hasattr(pkg, '__file__'):
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return
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pkg_path = os.path.dirname(pkg.__file__)
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try:
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fp, path, ext = imp.find_module(modname, [pkg_path])
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LOG.error('%r', (fp, path, ext))
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return path, fp.read(), False
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except ImportError, e:
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LOG.debug('imp.find_module(%r, %r) -> %s', modname, [pkg_path], e)
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get_module_methods = [_get_module_via_pkgutil,
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_get_module_via_sys_modules,
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_get_module_via_parent_enumeration]
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def _on_get_module(self, msg):
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LOG.debug('%r.get_module(%r)', self, msg)
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if msg == econtext.core._DEAD:
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return
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fullname = msg.data
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try:
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for method in self.get_module_methods:
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tup = method(self, fullname)
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if tup:
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break
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try:
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path, source, is_pkg = tup
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except TypeError:
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raise ImportError('could not find %r' % (fullname,))
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LOG.debug('%s found %r: (%r, .., %r)',
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method.__name__, fullname, path, is_pkg)
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if is_pkg:
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pkg_present = get_child_modules(path, fullname)
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LOG.debug('get_child_modules(%r, %r) -> %r',
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path, fullname, pkg_present)
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else:
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pkg_present = None
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compressed = zlib.compress(source)
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self._router.route(
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econtext.core.Message.pickled(
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(pkg_present, path, compressed),
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dst_id=msg.src_id,
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handle=msg.reply_to,
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)
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)
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except Exception:
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LOG.debug('While importing %r', fullname, exc_info=True)
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self._router.route(
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econtext.core.Message.pickled(
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None,
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dst_id=msg.src_id,
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handle=msg.reply_to,
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)
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)
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class ModuleForwarder(object):
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"""
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Respond to GET_MODULE requests in a slave by forwarding the request to our
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parent context, or satisfying the request from our local Importer cache.
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"""
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def __init__(self, router, parent_context, importer):
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self.router = router
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self.parent_context = parent_context
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self.importer = importer
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router.add_handler(self._on_get_module, econtext.core.GET_MODULE)
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def __repr__(self):
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return 'ModuleForwarder(%r)' % (self.router,)
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def _on_get_module(self, msg):
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LOG.debug('%r._on_get_module(%r)', self, msg)
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if msg == econtext.core._DEAD:
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return
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fullname = msg.data
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cached = self.importer._cache.get(fullname)
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if cached:
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self.router.route(
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econtext.core.Message.pickled(
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cached,
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dst_id=msg.src_id,
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handle=msg.reply_to,
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)
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)
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else:
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self.parent_context.send(
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econtext.core.Message(
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data=msg.data,
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handle=econtext.core.GET_MODULE,
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reply_to=self.parent_context.add_handler(
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lambda m: self._on_got_source(m, msg),
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persist=False
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)
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)
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)
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def _on_got_source(self, msg, original_msg):
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LOG.debug('%r._on_got_source(%r, %r)', self, msg, original_msg)
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fullname = original_msg.data
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self.importer._cache[fullname] = msg.unpickle()
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self.router.route(
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econtext.core.Message(
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data=msg.data,
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dst_id=original_msg.src_id,
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handle=original_msg.reply_to,
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)
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)
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class Message(econtext.core.Message):
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"""
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Message subclass that controls unpickling.
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"""
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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 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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class Stream(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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message_class = Message
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#: The path to the remote Python interpreter.
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python_path = 'python2.7'
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#: True to cause context to write verbose /tmp/econtext.<pid>.log.
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debug = False
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def construct(self, remote_name=None, python_path=None, debug=False, **kwargs):
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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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super(Stream, self).construct(**kwargs)
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if python_path:
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self.python_path = python_path
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if remote_name is None:
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remote_name = '%s@%s:%d'
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remote_name %= (getpass.getuser(), socket.gethostname(), os.getpid())
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self.remote_name = remote_name
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self.debug = debug
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def on_shutdown(self, broker):
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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.send(
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econtext.core.Message.pickled(
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econtext.core._DEAD,
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src_id=econtext.context_id,
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dst_id=self.remote_id,
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handle=econtext.core.CALL_FUNCTION
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)
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)
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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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R2,W2=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.dup2(R2,101)
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for f in R,R2,W,W2: os.close(f)
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os.environ['ARGV0'] = `[sys.executable]`
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os.execv(sys.executable,['econtext:CONTEXT_NAME'])
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else:
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os.write(1, 'EC0\n')
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C = zlib.decompress(sys.stdin.read(input()))
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os.fdopen(W,'w',0).write(C)
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os.fdopen(W2,'w',0).write('%s\n%s' % (len(C),C))
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os.write(1, 'EC1\n')
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sys.exit(0)
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def get_boot_command(self):
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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', self.remote_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 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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econtext.context_id, # parent_id
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self.remote_id, # context_id
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self.key,
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self.debug,
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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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create_child = staticmethod(create_child)
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def connect(self):
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LOG.debug('%r.connect()', self)
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pid, fd = self.create_child(*self.get_boot_command())
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self.name = 'local.%s' % (pid,)
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self.receive_side = econtext.core.Side(self, fd)
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self.transmit_side = econtext.core.Side(self, os.dup(fd))
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LOG.debug('%r.connect(): child process stdin/stdout=%r',
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self, self.receive_side.fd)
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self._connect_bootstrap()
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def _ec0_received(self):
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LOG.debug('%r._ec0_received()', self)
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write_all(self.transmit_side.fd, self.get_preamble())
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discard_until(self.receive_side.fd, 'EC1\n', time.time() + 10.0)
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def _connect_bootstrap(self):
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discard_until(self.receive_side.fd, 'EC0\n', time.time() + 10.0)
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self._ec0_received()
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|
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class Broker(econtext.core.Broker):
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shutdown_timeout = 5.0
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|
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class Context(econtext.core.Context):
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via = None
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def on_disconnect(self, broker):
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pass
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def _discard_result(self, msg):
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data = msg.unpickle()
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if isinstance(data, Exception):
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try:
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raise data
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except Exception:
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LOG.exception('_discard_result')
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else:
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LOG.debug('_discard_result: %r', data)
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def call_async(self, with_context, fn, *args, **kwargs):
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LOG.debug('%r.call_async(%r, %r, *%r, **%r)',
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self, 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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self.send(
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econtext.core.Message.pickled(
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call,
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handle=econtext.core.CALL_FUNCTION,
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reply_to=self.add_handler(self._discard_result),
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)
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)
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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:`ExternalContext <econtext.core.ExternalContext>` instance as
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the 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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response = self.send_await(
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econtext.core.Message.pickled(
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call,
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handle=econtext.core.CALL_FUNCTION
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),
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deadline
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)
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decoded = response.unpickle()
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if isinstance(decoded, econtext.core.CallError):
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raise decoded
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return decoded
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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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|
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def _proxy_connect(econtext, name, context_id, klass, kwargs):
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|
if not isinstance(econtext.router, Router): # TODO
|
|
econtext.router.__class__ = Router # TODO
|
|
LOG.debug('_proxy_connect(): constructing ModuleForwarder')
|
|
ModuleForwarder(econtext.router, econtext.parent, econtext.importer)
|
|
|
|
context = econtext.router._connect(
|
|
context_id,
|
|
klass,
|
|
name=name,
|
|
**kwargs
|
|
)
|
|
return context.name
|
|
|
|
|
|
class Router(econtext.core.Router):
|
|
context_id_counter = itertools.count(1)
|
|
|
|
debug = False
|
|
|
|
def __init__(self, *args, **kwargs):
|
|
super(Router, self).__init__(*args, **kwargs)
|
|
self.responder = ModuleResponder(self)
|
|
self.log_forwarder = LogForwarder(self)
|
|
|
|
def enable_debug(self):
|
|
"""
|
|
Cause this context and any descendant child contexts to write debug
|
|
logs to /tmp/econtext.<pid>.log.
|
|
"""
|
|
econtext.core.enable_debug_logging()
|
|
self.debug = True
|
|
|
|
def __enter__(self):
|
|
return self
|
|
|
|
def __exit__(self, e_type, e_val, tb):
|
|
self.broker.shutdown()
|
|
self.broker.join()
|
|
|
|
def context_by_id(self, context_id):
|
|
return self._context_by_id.get(context_id)
|
|
|
|
def local(self, **kwargs):
|
|
return self.connect(Stream, **kwargs)
|
|
|
|
def sudo(self, **kwargs):
|
|
import econtext.sudo
|
|
return self.connect(econtext.sudo.Stream, **kwargs)
|
|
|
|
def ssh(self, **kwargs):
|
|
import econtext.ssh
|
|
return self.connect(econtext.ssh.Stream, **kwargs)
|
|
|
|
def _connect(self, context_id, klass, name=None, **kwargs):
|
|
context = Context(self, context_id)
|
|
stream = klass(self, context.context_id, context.key, **kwargs)
|
|
stream.connect()
|
|
context.name = name or stream.name
|
|
self.register(context, stream)
|
|
return context
|
|
|
|
def connect(self, klass, name=None, **kwargs):
|
|
kwargs.setdefault('debug', self.debug)
|
|
|
|
via = kwargs.pop('via', None)
|
|
if via is not None:
|
|
return self.proxy_connect(via, klass, name=name, **kwargs)
|
|
|
|
context_id = self.context_id_counter.next()
|
|
return self._connect(context_id, klass, name=name, **kwargs)
|
|
|
|
def proxy_connect(self, via_context, klass, name=None, **kwargs):
|
|
context_id = self.context_id_counter.next()
|
|
# Must be added prior to _proxy_connect() to avoid a race.
|
|
self.add_route(context_id, via_context.context_id)
|
|
name = via_context.call_with_deadline(None, True,
|
|
_proxy_connect, name, context_id, klass, kwargs
|
|
)
|
|
# name = '%s.%s' % (via_context.name, name)
|
|
context = Context(self, context_id, name=name)
|
|
context.via = via_context
|
|
|
|
child = via_context
|
|
parent = via_context.via
|
|
while parent is not None:
|
|
LOG.debug('Adding route to %r for %r via %r', parent, context, child)
|
|
parent.send(
|
|
econtext.core.Message(
|
|
data='%s\x00%s' % (context_id, child.context_id),
|
|
handle=econtext.core.ADD_ROUTE,
|
|
)
|
|
)
|
|
child = parent
|
|
parent = parent.via
|
|
|
|
self._context_by_id[context.context_id] = context
|
|
return context
|