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330 lines
12 KiB
Python
330 lines
12 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 getpass
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import imp
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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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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('econtext.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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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, parentfp
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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 __repr__(self):
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return 'ModuleResponder(%r)' % (self._context,)
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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 get_module(self, data):
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LOG.debug('%r.get_module(%r)', 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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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('%r returned for %r: (%r, .., %r)',
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method, 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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reply = (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 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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#: The path to the remote Python interpreter.
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python_path = sys.executable
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def __init__(self, context):
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super(Stream, self).__init__(context)
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self._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 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.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', 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.receive_side = econtext.core.Side(self, os.dup(sock.fileno()))
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self.transmit_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.receive_side.fd)
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econtext.core.write_all(self.transmit_side.fd, self.get_preamble())
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s = os.read(self.receive_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 Broker(econtext.core.Broker):
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shutdown_timeout = 5.0
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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, broker):
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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:`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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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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def connect(broker, 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(broker, name)
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context.stream = Stream(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 broker.register(context)
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