#!/usr/bin/env python
# DefaultClusterDriver.py
#
#   Copyright (C) 2006 CCLRC, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is 
#   included in the root directory of this package.
#
# 19th June 2006
# 
# A general ClusterDriver which should be inherited from for specific
# cluster driver implementations. This provides facility for recording
# jobs finishing, writing scripts etc, but not the queue-specific
# submission, which should be handled by classes derived from this.
# 

import os
import time

from DefaultDriver import DefaultDriver
from DriverHelper import script_writer
from DriverHelper import executable_exists

class DefaultClusterDriver(DefaultDriver):
    '''A general class for Driving programs on clusters. This should not
    be used directly!'''

    def __init__(self):

        if os.name != 'posix':
            raise RuntimeError, 'os "%s" not supported' % os.name
        
        DefaultDriver.__init__(self)

        self._script_command_line = []
        self._script_standard_input = []

        self._script_name = self._name

        self._script_status = 0

        # this is opened by the close() method and read by output
        # from self._script_name.xout
        
        self._output_file = None

        return

    def set_name(self, name):
        '''Set the name to something sensible.'''
        self._script_name = name
        
        return

    def start(self):
        '''This is pretty meaningless in terms of running things through
        scripts...'''
        
        for c in self._command_line:
            self._script_command_line.append(c)

    def submit(self):
        '''Submit to the queue - this MUST be overloaded.'''
        raise RuntimeError, 'do not use this class directly'

    def cleanup(self):
        '''Cleanup after the job is finished.'''
        raise RuntimeError, 'do not use this class directly'

    def check(self):
        '''NULL overloading of the default check method.'''
        return True

    def _check_executable_old(self, executable):
        '''Overload the check method to always be True. This handles the
        strange setups you find on clusters.'''
        
        return True

    def _check_executable(self, executable):
        '''Pass this on to executable_exists.'''

        return executable_exists(executable)

    def _input(self, record):
        self._script_standard_input.append(record)

        return

    def _output(self):
        return self._output_file.readline()

    def _status(self):
        return self._script_status

    def close(self):
        '''This is where most of the work will be done - in here is
        where the script itself gets written and run, and the output
        file channel opened when the process has finished...'''

        # ensure that there is no .xstatus file here

        script_writer(self._working_directory,
                      self._script_name,
                      self._executable,
                      self._script_command_line,
                      self._working_environment,
                      self._script_standard_input,
                      mkdirs = self._scratch_directories)

        # call the queue submission - this will be overloaded
        self.submit()

        # now have a while loop watching for the .xstatus file
        # using os.path.exists()
        
        xstatus_file = os.path.join(self._working_directory,
                                    '%s.xstatus' % self._script_name)

        while True:
            if os.path.exists(xstatus_file):
                time.sleep(1)
                break
            time.sleep(5)

        try:
            self._script_status = int(open(xstatus_file, 'r').read())
        except:
            self._script_status = 0

        # set this up for reading the "standard output" of the job.
        self._output_file = open(os.path.join(self._working_directory,
                                              '%s.xout' % self._script_name),
                                 'r')

        self.cleanup()

        return

    def kill(self):
        '''This is meaningless...'''

        pass

    
