parallel/__init__.py

# This file was automatically generated by SWIG (http://www.swig.org).
# Version 3.0.10
#
# Do not make changes to this file unless you know what you are doing--modify
# the SWIG interface file instead.

# This wrapper is part of IMP,
# Copyright 2007-2018 IMP Inventors. All rights reserved.

from __future__ import print_function, division, absolute_import




from sys import version_info as _swig_python_version_info
if _swig_python_version_info >= (2, 7, 0):
    def swig_import_helper():
        import importlib
        pkg = __name__.rpartition('.')[0]
        mname = '.'.join((pkg, '_IMP_parallel')).lstrip('.')
        try:
            return importlib.import_module(mname)
        except ImportError:
            return importlib.import_module('_IMP_parallel')
    _IMP_parallel = swig_import_helper()
    del swig_import_helper
elif _swig_python_version_info >= (2, 6, 0):
    def swig_import_helper():
        from os.path import dirname
        import imp
        fp = None
        try:
            fp, pathname, description = imp.find_module('_IMP_parallel', [dirname(__file__)])
        except ImportError:
            import _IMP_parallel
            return _IMP_parallel
        if fp is not None:
            try:
                _mod = imp.load_module('_IMP_parallel', fp, pathname, description)
            finally:
                fp.close()
            return _mod
    _IMP_parallel = swig_import_helper()
    del swig_import_helper
else:
    import _IMP_parallel
del _swig_python_version_info
try:
    _swig_property = property
except NameError:
    pass  # Python < 2.2 doesn't have 'property'.

try:
    import builtins as __builtin__
except ImportError:
    import __builtin__

def _swig_setattr_nondynamic(self, class_type, name, value, static=1):
    if (name == "thisown"):
        return self.this.own(value)
    if (name == "this"):
        if type(value).__name__ == 'SwigPyObject':
            self.__dict__[name] = value
            return
    method = class_type.__swig_setmethods__.get(name, None)
    if method:
        return method(self, value)
    if (not static):
        object.__setattr__(self, name, value)
    else:
        raise AttributeError("You cannot add attributes to %s" % self)


def _swig_setattr(self, class_type, name, value):
    return _swig_setattr_nondynamic(self, class_type, name, value, 0)


def _swig_getattr(self, class_type, name):
    if (name == "thisown"):
        return self.this.own()
    method = class_type.__swig_getmethods__.get(name, None)
    if method:
        return method(self)
    raise AttributeError("'%s' object has no attribute '%s'" % (class_type.__name__, name))


def _swig_repr(self):
    try:
        strthis = "proxy of " + self.this.__repr__()
    except __builtin__.Exception:
        strthis = ""
    return "<%s.%s; %s >" % (self.__class__.__module__, self.__class__.__name__, strthis,)


def _swig_setattr_nondynamic_method(set):
    def set_attr(self, name, value):
        if (name == "thisown"):
            return self.this.own(value)
        if hasattr(self, name) or (name == "this"):
            set(self, name, value)
        else:
            raise AttributeError("You cannot add attributes to %s" % self)
    return set_attr


try:
    import weakref
    weakref_proxy = weakref.proxy
except __builtin__.Exception:
    weakref_proxy = lambda x: x


class IMP_PARALLEL_SwigPyIterator(object):
    """Proxy of C++ swig::IMP_PARALLEL_SwigPyIterator class."""

    thisown = _swig_property(lambda x: x.this.own(), lambda x, v: x.this.own(v), doc='The membership flag')

    def __init__(self, *args, **kwargs):
        raise AttributeError("No constructor defined - class is abstract")
    __repr__ = _swig_repr
    __swig_destroy__ = _IMP_parallel.delete_IMP_PARALLEL_SwigPyIterator
    __del__ = lambda self: None

    def value(self):
        """value(IMP_PARALLEL_SwigPyIterator self) -> PyObject *"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_value(self)


    def incr(self, n=1):
        """
        incr(IMP_PARALLEL_SwigPyIterator self, size_t n=1) -> IMP_PARALLEL_SwigPyIterator
        incr(IMP_PARALLEL_SwigPyIterator self) -> IMP_PARALLEL_SwigPyIterator
        """
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_incr(self, n)


    def decr(self, n=1):
        """
        decr(IMP_PARALLEL_SwigPyIterator self, size_t n=1) -> IMP_PARALLEL_SwigPyIterator
        decr(IMP_PARALLEL_SwigPyIterator self) -> IMP_PARALLEL_SwigPyIterator
        """
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_decr(self, n)


    def distance(self, x):
        """distance(IMP_PARALLEL_SwigPyIterator self, IMP_PARALLEL_SwigPyIterator x) -> ptrdiff_t"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_distance(self, x)


    def equal(self, x):
        """equal(IMP_PARALLEL_SwigPyIterator self, IMP_PARALLEL_SwigPyIterator x) -> bool"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_equal(self, x)


    def copy(self):
        """copy(IMP_PARALLEL_SwigPyIterator self) -> IMP_PARALLEL_SwigPyIterator"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_copy(self)


    def next(self):
        """next(IMP_PARALLEL_SwigPyIterator self) -> PyObject *"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_next(self)


    def __next__(self):
        """__next__(IMP_PARALLEL_SwigPyIterator self) -> PyObject *"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___next__(self)


    def previous(self):
        """previous(IMP_PARALLEL_SwigPyIterator self) -> PyObject *"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_previous(self)


    def advance(self, n):
        """advance(IMP_PARALLEL_SwigPyIterator self, ptrdiff_t n) -> IMP_PARALLEL_SwigPyIterator"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator_advance(self, n)


    def __eq__(self, x):
        """__eq__(IMP_PARALLEL_SwigPyIterator self, IMP_PARALLEL_SwigPyIterator x) -> bool"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___eq__(self, x)


    def __ne__(self, x):
        """__ne__(IMP_PARALLEL_SwigPyIterator self, IMP_PARALLEL_SwigPyIterator x) -> bool"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___ne__(self, x)


    def __iadd__(self, n):
        """__iadd__(IMP_PARALLEL_SwigPyIterator self, ptrdiff_t n) -> IMP_PARALLEL_SwigPyIterator"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___iadd__(self, n)


    def __isub__(self, n):
        """__isub__(IMP_PARALLEL_SwigPyIterator self, ptrdiff_t n) -> IMP_PARALLEL_SwigPyIterator"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___isub__(self, n)


    def __add__(self, n):
        """__add__(IMP_PARALLEL_SwigPyIterator self, ptrdiff_t n) -> IMP_PARALLEL_SwigPyIterator"""
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___add__(self, n)


    def __sub__(self, *args):
        """
        __sub__(IMP_PARALLEL_SwigPyIterator self, ptrdiff_t n) -> IMP_PARALLEL_SwigPyIterator
        __sub__(IMP_PARALLEL_SwigPyIterator self, IMP_PARALLEL_SwigPyIterator x) -> ptrdiff_t
        """
        return _IMP_parallel.IMP_PARALLEL_SwigPyIterator___sub__(self, *args)

    def __iter__(self):
        return self
IMP_PARALLEL_SwigPyIterator_swigregister = _IMP_parallel.IMP_PARALLEL_SwigPyIterator_swigregister
IMP_PARALLEL_SwigPyIterator_swigregister(IMP_PARALLEL_SwigPyIterator)


_value_types=[]
_object_types=[]
_raii_types=[]
_plural_types=[]

IMP_DEBUG = _IMP_parallel.IMP_DEBUG
IMP_RELEASE = _IMP_parallel.IMP_RELEASE
IMP_SILENT = _IMP_parallel.IMP_SILENT
IMP_PROGRESS = _IMP_parallel.IMP_PROGRESS
IMP_TERSE = _IMP_parallel.IMP_TERSE
IMP_VERBOSE = _IMP_parallel.IMP_VERBOSE
IMP_MEMORY = _IMP_parallel.IMP_MEMORY
IMP_NONE = _IMP_parallel.IMP_NONE
IMP_USAGE = _IMP_parallel.IMP_USAGE
IMP_INTERNAL = _IMP_parallel.IMP_INTERNAL
IMP_KERNEL_HAS_LOG4CXX = _IMP_parallel.IMP_KERNEL_HAS_LOG4CXX
IMP_COMPILER_HAS_AUTO = _IMP_parallel.IMP_COMPILER_HAS_AUTO
IMP_COMPILER_HAS_DEBUG_VECTOR = _IMP_parallel.IMP_COMPILER_HAS_DEBUG_VECTOR
IMP_COMPILER_HAS_UNIQUE_PTR = _IMP_parallel.IMP_COMPILER_HAS_UNIQUE_PTR
IMP_KERNEL_HAS_BOOST_RANDOM = _IMP_parallel.IMP_KERNEL_HAS_BOOST_RANDOM
IMP_KERNEL_HAS_GPERFTOOLS = _IMP_parallel.IMP_KERNEL_HAS_GPERFTOOLS
IMP_KERNEL_HAS_TCMALLOC_HEAPCHECKER = _IMP_parallel.IMP_KERNEL_HAS_TCMALLOC_HEAPCHECKER
IMP_KERNEL_HAS_TCMALLOC_HEAPPROFILER = _IMP_parallel.IMP_KERNEL_HAS_TCMALLOC_HEAPPROFILER
IMPKERNEL_SHOW_WARNINGS = _IMP_parallel.IMPKERNEL_SHOW_WARNINGS

import sys
class _DirectorObjects(object):
    """@internal Simple class to keep references to director objects
       to prevent premature deletion."""
    def __init__(self):
        self._objects = []
    def register(self, obj):
        """Take a reference to a director object; will only work for
           refcounted C++ classes"""
        if hasattr(obj, 'get_ref_count'):
            self._objects.append(obj)
    def cleanup(self):
        """Only drop our reference and allow cleanup by Python if no other
           Python references exist (we hold 3 references: one in self._objects,
           one in x, and one in the argument list for getrefcount) *and* no
           other C++ references exist (the Python object always holds one)"""
        objs = [x for x in self._objects if sys.getrefcount(x) > 3 \
                                         or x.get_ref_count() > 1]
# Do in two steps so the references are kept until the end of the
# function (deleting references may trigger a fresh call to this method)
        self._objects = objs
    def get_object_count(self):
        """Get number of director objects (useful for testing only)"""
        return len(self._objects)
_director_objects = _DirectorObjects()

class _ostream(object):
    """Proxy of C++ std::ostream class."""

    thisown = _swig_property(lambda x: x.this.own(), lambda x, v: x.this.own(v), doc='The membership flag')

    def __init__(self, *args, **kwargs):
        raise AttributeError("No constructor defined")
    __repr__ = _swig_repr

    def write(self, osa_buf):
        """write(_ostream self, char const * osa_buf)"""
        return _IMP_parallel._ostream_write(self, osa_buf)

_ostream_swigregister = _IMP_parallel._ostream_swigregister
_ostream_swigregister(_ostream)

IMP_COMPILER_HAS_OVERRIDE = _IMP_parallel.IMP_COMPILER_HAS_OVERRIDE
IMP_COMPILER_HAS_FINAL = _IMP_parallel.IMP_COMPILER_HAS_FINAL
IMP_HAS_NOEXCEPT = _IMP_parallel.IMP_HAS_NOEXCEPT
IMP_C_OPEN_BINARY = _IMP_parallel.IMP_C_OPEN_BINARY
import IMP
IMP_PARALLEL_HAS_BOOST_FILESYSTEM = _IMP_parallel.IMP_PARALLEL_HAS_BOOST_FILESYSTEM
IMP_PARALLEL_HAS_BOOST_PROGRAMOPTIONS = _IMP_parallel.IMP_PARALLEL_HAS_BOOST_PROGRAMOPTIONS
IMP_PARALLEL_HAS_BOOST_RANDOM = _IMP_parallel.IMP_PARALLEL_HAS_BOOST_RANDOM
IMP_PARALLEL_HAS_BOOST_SYSTEM = _IMP_parallel.IMP_PARALLEL_HAS_BOOST_SYSTEM
IMPPARALLEL_SHOW_WARNINGS = _IMP_parallel.IMPPARALLEL_SHOW_WARNINGS


import socket
import time
import sys
import os
import re
import random
import socket
import xdrlib
try:
    import cPickle as pickle
except ImportError:
    import pickle
from IMP.parallel import slavestate
from IMP.parallel.subproc import _run_background, _Popen4
from IMP.parallel.util import _ListenSocket, _ErrorWrapper
from IMP.parallel.util import _TaskWrapper, _HeartBeat, _ContextWrapper
from IMP.parallel.util import _SetPathAction

# Save sys.path at import time, so that slaves can import using the same
# path that works for the master imports
_import_time_path = sys.path[:]

class Error(Exception):
    """Base class for all errors specific to the parallel module"""
    pass


class _NoMoreTasksError(Error):
    pass


class NoMoreSlavesError(Error):
    """Error raised if all slaves failed, so tasks cannot be run"""
    pass


class NetworkError(Error):
    """Error raised if a problem occurs with the network"""
    pass


class RemoteError(Error):
    """Error raised if a slave has an unhandled exception"""
    def __init__(self, exc, traceback, slave):
        self.exc = exc
        self.traceback = traceback
        self.slave = slave

    def __str__(self):
        errstr = str(self.exc.__class__).replace("exceptions.", "")
        return "%s: %s from %s\nRemote traceback:\n%s" \
               % (errstr, str(self.exc), str(self.slave), self.traceback)

class _Communicator(object):
    """Simple support for sending Python pickled objects over the network"""

    def __init__(self):
        self._socket = None
        self._ibuffer = b''

    def _send(self, obj):
        p = xdrlib.Packer()
        try:
            p.pack_string(pickle.dumps(obj, -1))
# Python < 2.5 can fail trying to send Inf or NaN floats in binary
# mode, so fall back to the old protocol in this case:
        except SystemError:
            p.pack_string(pickle.dumps(obj, 0))
        self._socket.sendall(p.get_buffer())

    def get_data_pending(self):
        return len(self._ibuffer) > 0

    def _recv(self):
        while True:
            try:
                obj, self._ibuffer = self._unpickle(self._ibuffer)
                if isinstance(obj, _ErrorWrapper):
                    raise RemoteError(obj.obj, obj.traceback, self)
                else:
                    return obj
            except (IndexError, EOFError):
                try:
                    data = self._socket.recv(4096)
                except socket.error as detail:
                    raise NetworkError("Connection lost to %s: %s" \
                                       % (str(self), str(detail)))
                if len(data) > 0:
                    self._ibuffer += data
                else:
                    raise NetworkError("%s closed connection" % str(self))

    def _unpickle(self, ibuffer):
        p = xdrlib.Unpacker(ibuffer)
        obj = p.unpack_string()
        return (pickle.loads(obj), ibuffer[p.get_position():])


class Slave(_Communicator):
    """Representation of a single slave.
       Each slave uses a single thread of execution (i.e. a single CPU core)
       to run tasks sequentially.
       Slave is an abstract class; instead of using this class directly, use
       a subclass such as LocalSlave or SGEQsubSlaveArray."""

    def __init__(self):
        _Communicator.__init__(self)
        self._state = slavestate.init
        self._context = None
        self._task = None
        self.update_contact_time()

    def _start(self, command, unique_id, output):
        """Start the slave running on the remote host; override in subclasses"""
        self._state = slavestate.started

    def _accept_connection(self, sock):
        self._socket = sock
        self._state = slavestate.connected
        self.update_contact_time()

    def _set_python_search_path(self, path):
        self._send(_SetPathAction(path))

    def update_contact_time(self):
        self.last_contact_time = time.time()

    def get_contact_timed_out(self, timeout):
        return (time.time() - self.last_contact_time) > timeout

    def _start_task(self, task, context):
        if not self._ready_for_task(context) and not self._ready_for_task(None):
            raise TypeError("%s not ready for task" % str(self))
        if self._context != context:
            self._context = context
            self._send(_ContextWrapper(context._startup))
        self._state = slavestate.running_task
        self._task = task
        self._send(_TaskWrapper(task))

    def _get_finished_task(self):
        while True:
            r = self._recv()
            self.update_contact_time()
            if isinstance(r, _HeartBeat):
                if not self.get_data_pending():
                    return None
            else:
                break
        task = self._task
        task._results = r
        self._task = None
        self._state = slavestate.connected
        return task

    def _kill(self):
        task = self._task
        self._task = None
        self._context = None
        self._state = slavestate.dead
        return task

    def _ready_to_start(self):
        return self._state == slavestate.init

    def _ready_for_task(self, context):
        return self._state == slavestate.connected \
               and self._context == context

    def _running_task(self, context):
        return self._state == slavestate.running_task \
               and self._context == context


class SlaveArray(object):
    """Representation of an array of slaves.
       This is similar to Slave, except that it represents a collection of
       slaves that are controlled together, such as a batch submission system
       array job on a compute cluster.
       Slave is an abstract class; instead of using this class directly, use
       a subclass such as SGEQsubSlaveArray."""

    def _get_slaves(self):
        """Return a list of Slave objects contained within this array"""
        pass

    def _start(self):
        """Do any necessary startup after all contained Slaves have started"""
        pass


class LocalSlave(Slave):
    """A slave running on the same machine as the master."""

    def _start(self, command, unique_id, output):
        Slave._start(self, command, unique_id, output)
        cmdline = "%s %s" % (command, unique_id)
        _run_background(cmdline, output)

    def __repr__(self):
        return "<LocalSlave>"


class _SGEQsubSlave(Slave):
    def __init__(self, array):
        Slave.__init__(self)
        self._jobid = None
        self._array = array

    def _start(self, command, unique_id, output):
        Slave._start(self, command, unique_id, output)
        self._array._slave_started(unique_id, output, self)

    def __repr__(self):
        jobid = self._jobid
        if jobid is None:
            jobid = '(unknown)'
        return "<SGE qsub slave, ID %s>" % jobid


class SGEQsubSlaveArray(SlaveArray):
    """An array of slaves on a Sun Grid Engine system, started with 'qsub'.
       To use this class, the master process must be running on a machine that
       can submit Sun Grid Engine (SGE) jobs using the 'qsub' command (this
       is termed a 'submit host' by SGE). The class starts an SGE job array
       (every slave has the same SGE job ID, but a different task ID).
    """


    standard_options = '-j y -cwd -r n -o sge-errors'

    def __init__(self, numslave, options):
        """Constructor.
           @param numslave The number of slaves, which corresponds to the
                           number of tasks in the SGE job.
           @param options  A string of SGE options that are passed on the 'qsub'
                           command line. This is added to standard_options.
        """
        self._numslave = numslave
        self._options = options
        self._starting_slaves = []
        self._jobid = None

    def _get_slaves(self):
        """Return a list of Slave objects contained within this array"""
        return [_SGEQsubSlave(self) for x in range(self._numslave)]

    def _slave_started(self, command, output, slave):
        self._starting_slaves.append((command, output, slave))

    def _start(self, command):
        qsub = "qsub -S /bin/sh %s %s -t 1-%d" % \
               (self._options, self.standard_options,
                len(self._starting_slaves))
        print(qsub)
        a = _Popen4(qsub)
        (inp, out) = (a.stdin, a.stdout)
        slave_uid = " ".join([repr(s[0]) for s in self._starting_slaves])
        slave_out = " ".join([repr(s[1]) for s in self._starting_slaves])
        inp.write("#!/bin/sh\n")
        inp.write("uid=( '' %s )\n" % slave_uid)
        inp.write("out=( '' %s )\n" % slave_out)
        inp.write("myuid=${uid[$SGE_TASK_ID]}\n")
        inp.write("myout=${out[$SGE_TASK_ID]}\n")
        inp.write("%s $myuid > $myout 2>&1\n" % command)
        inp.close()
        outlines = out.readlines()
        out.close()
        for line in outlines:
            print(line.rstrip('\r\n'))
        a.require_clean_exit()
        self._set_jobid(outlines)
        self._starting_slaves = []

    def _set_jobid(self, outlines):
        """Try to figure out the job ID from the SGE qsub output"""
        if len(outlines) > 0:
            m = re.compile(r"\d+").search(outlines[0])
            if m:
                self._jobid = int(m.group())
                for (num, slave) in enumerate(self._starting_slaves):
                    slave[2]._jobid = "%d.%d" % (self._jobid, num+1)


class _SGEPESlave(Slave):
    def __init__(self, host):
        Slave.__init__(self)
        self._host = host

    def _start(self, command, unique_id, output):
        Slave._start(self, command, unique_id, output)
        cmdline = "qrsh -inherit -V %s %s %s" % (self._host, command, unique_id)
        _run_background(cmdline, output)

    def __repr__(self):
        return "<SGE PE slave on %s>" % self._host


class SGEPESlaveArray(SlaveArray):
    """An array of slaves in a Sun Grid Engine system parallel environment.
       In order to use this class, the master must be run via Sun Grid Engine's
       'qsub' command and submitted to a parallel environment using the qsub
       -pe option. This class will start slaves on every node in the parallel
       environment (including the node running the master). Each slave is
       started using the 'qrsh' command with the '-inherit' option."""

    def _get_slaves(self):
        slaves = []

        pe = os.environ['PE_HOSTFILE']
        fh = open(pe, "r")
        while True:
            line = fh.readline()
            if line == '':
                break
            (node, num, queue) = line.split(None, 2)
            for i in range(int(num)):
                slaves.append(_SGEPESlave(node))
# Replace first slave with a local slave, as this is ourself, and SGE
# won't let us start this process with qrsh (as we are already
# occupying the slot)
        if len(slaves) > 0:
            slaves[0] = LocalSlave()
        return slaves


class Context(object):
    """A collection of tasks that run in the same environment.
       Context objects are typically created by calling Manager::get_context().
    """
    def __init__(self, manager, startup=None):
        """Constructor."""
        self._manager = manager
        self._startup = startup
        self._tasks = []

    def add_task(self, task):
        """Add a task to this context.
           Tasks are any Python callable object that can be pickled (e.g. a
           function or a class that implements the \_\_call\_\_ method). When
           the task is run on the slave its arguments are the return value
           from this context's startup function."""
        self._tasks.append(task)

    def get_results_unordered(self):
        """Run all of the tasks on available slaves, and return results.
           If there are more tasks than slaves, subsequent tasks are
           started only once a running task completes: each slave only runs
           a single task at a time. As each task completes, the return value(s)
           from the task callable are returned from this method, as a
           Python generator. Note that the results are returned in the order
           that tasks complete, which may not be the same as the order they
           were submitted in.

           @exception NoMoreSlavesError there are no slaves available
                      to run the tasks (or they all failed during execution).
           @exception RemoteError a slave encountered an unhandled exception.
           @exception NetworkError the master lost (or was unable to
                      establish) communication with any slave.
        """
        return self._manager._get_results_unordered(self)


class Manager(object):
    """Manages slaves and contexts.
    """

    connect_timeout = 7200

# Note: must be higher than that in slave_handler._HeartBeatThread
    heartbeat_timeout = 7200

    def __init__(self, python=None, host=None, output='slave%d.output'):
        """Constructor.
           @param python If not None, the command to run to start a Python
                         interpreter that can import the IMP module. Otherwise,
                         the same interpreter that the master is currently using
                         is used. This is passed to the shell, so a full command
                         line (including multiple words separated by spaces) can
                         be used if necessary.
           @param host   The hostname that slaves use to connect back to the
                         master. If not specified, the master machine's primary
                         IP address is used. On multi-homed machines, such as
                         compute cluster headnodes, this may need to be changed
                         to allow all slaves to reach the master (typically the
                         name of the machine's internal network address is
                         needed). If only running local slaves, 'localhost' can
                         be used to prohibit connections across the network.
           @param output A format string used to name slave output files. It is
                         given the numeric slave id, so for example the default
                         value 'slave\%d.output' will yield output files called
                         slave0.output, slave1.output, etc.
        """
        if python is None:
            self._python = sys.executable
        else:
            self._python = python
        self._host = host
        self._output = output
        self._all_slaves = []
        self._starting_slaves = {}
        self._slave_arrays = []
        if host:
            self._host = host
        else:
# Get primary IP address of this machine
            self._host = socket.gethostbyname_ex(socket.gethostname())[-1][0]
        self._listen_sock = _ListenSocket(self._host, self.connect_timeout)

    def add_slave(self, slave):
        """Add a Slave object."""
        if hasattr(slave, '_get_slaves'):
            self._slave_arrays.append(slave)
        else:
            self._all_slaves.append(slave)

    def get_context(self, startup=None):
        """Create and return a new Context in which tasks can be run.
           @param startup If not None, a callable (Python function or class
                          that implements the \_\_call\_\_ method) that sets up
                          the slave to run tasks. This method is only called
                          once per slave. The return values from this method
                          are passed to the task object when it runs on
                          the slave.
           @return A new Context object.
        """
        return Context(self, startup)

    def _get_results_unordered(self, context):
        """Run all of a context's tasks, and yield results"""
        self._send_tasks_to_slaves(context)
        try:
            while True:
                for task in self._get_finished_tasks(context):
                    tasks_queued = len(context._tasks)
                    yield task._results
# If the user added more tasks while processing these
# results, make sure they get sent off to the slaves 
                    if len(context._tasks) > tasks_queued:
                        self._send_tasks_to_slaves(context)
        except _NoMoreTasksError:
            return

    def _start_all_slaves(self):
        for array in self._slave_arrays:
            self._all_slaves.extend(array._get_slaves())

        command = ("%s -c \"import IMP.parallel.slave_handler as s; s.main()\" "
                   "%s %d") % (self._python, self._host, self._listen_sock.port)

        for (num, slave) in enumerate(self._all_slaves):
            if slave._ready_to_start():
                unique_id = self._get_unique_id(num)
                self._starting_slaves[unique_id] = slave
                slave._start(command, unique_id, self._output % num)

        for array in self._slave_arrays:
            array._start(command)
        self._slave_arrays = []

    def _get_unique_id(self, num):
        id = "%d:" % num
        for i in range(0, 8):
            id += chr(random.randint(0, 25) + ord('A'))
        return id

    def _send_tasks_to_slaves(self, context):
        self._start_all_slaves()
# Prefer slaves that already have the task context
        available_slaves = [a for a in self._all_slaves
                            if a._ready_for_task(context)] + \
                           [a for a in self._all_slaves
                            if a._ready_for_task(None)]
        for slave in available_slaves:
            if len(context._tasks) == 0:
                break
            else:
                self._send_task_to_slave(slave, context)

    def _send_task_to_slave(self, slave, context):
        if len(context._tasks) == 0:
            return
        t = context._tasks[0]
        try:
            slave._start_task(t, context)
            context._tasks.pop(0)
        except socket.error as detail:
            slave._kill()

    def _get_finished_tasks(self, context):
        while True:
            events = self._get_network_events(context)
            if len(events) == 0:
                self._kill_all_running_slaves(context)
            for event in events:
                task = self._process_event(event, context)
                if task:
                    yield task

    def _process_event(self, event, context):
        if event == self._listen_sock:
# New slave just connected
            (conn, addr) = self._listen_sock.accept()
            new_slave = self._accept_slave(conn, context)
        elif event._running_task(context):
            try:
                task = event._get_finished_task()
                if task:
                    self._send_task_to_slave(event, context)
                    return task
                else: # the slave sent back a heartbeat
                    self._kill_timed_out_slaves(context)
            except NetworkError as detail:
                task = event._kill()
                print("Slave %s failed (%s): rescheduling task %s" \
                      % (str(event), str(detail), str(task)))
                context._tasks.append(task)
                self._send_tasks_to_slaves(context)
        else:
            pass # Slave not running a task

    def _kill_timed_out_slaves(self, context):
        timed_out = [a for a in self._all_slaves if a._running_task(context) \
                     and a.get_contact_timed_out(self.heartbeat_timeout)]
        for slave in timed_out:
            task = slave._kill()
            print("Did not hear from slave %s in %d seconds; rescheduling "
                  "task %s" % (str(slave), self.heartbeat_timeout, str(task)))
            context._tasks.append(task)
        if len(timed_out) > 0:
            self._send_tasks_to_slaves(context)

    def _kill_all_running_slaves(self, context):
        running = [a for a in self._all_slaves if a._running_task(context)]
        for slave in running:
            task = slave._kill()
            context._tasks.append(task)
        raise NetworkError("Did not hear from any running slave in "
                           "%d seconds" % self.heartbeat_timeout)

    def _accept_slave(self, sock, context):
        sock.setblocking(True)
        identifier = sock.recv(1024)
        if identifier:
            identifier = identifier.decode('ascii')
        if identifier and identifier in self._starting_slaves:
            slave = self._starting_slaves.pop(identifier)
            slave._accept_connection(sock)
            print("Identified slave %s " % str(slave))
            self._init_slave(slave)
            self._send_task_to_slave(slave, context)
            return slave
        else:
            print("Ignoring request from unknown slave")

    def _init_slave(self, slave):
        if _import_time_path[0] != '':
            slave._set_python_search_path(_import_time_path[0])
        if sys.path[0] != '' and sys.path[0] != _import_time_path[0]:
            slave._set_python_search_path(sys.path[0])

    def _get_network_events(self, context):
        running = [a for a in self._all_slaves if a._running_task(context)]
        if len(running) == 0:
            if len(context._tasks) == 0:
                raise _NoMoreTasksError()
            elif len(self._starting_slaves) == 0:
                raise NoMoreSlavesError("Ran out of slaves to run tasks")
# Otherwise, wait for starting slaves to connect back and get tasks

        return util._poll_events(self._listen_sock, running,
                                 self.heartbeat_timeout)



def get_module_version():
    """get_module_version() -> std::string const"""
    return _IMP_parallel.get_module_version()

def get_example_path(fname):
    """get_example_path(std::string fname) -> std::string"""
    return _IMP_parallel.get_example_path(fname)

def get_data_path(fname):
    """get_data_path(std::string fname) -> std::string"""
    return _IMP_parallel.get_data_path(fname)

from . import _version_check
_version_check.check_version(get_module_version())
__version__ = get_module_version()