Package SimPy :: Module Simulation

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# Module Simulation

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    Simulation 2.0 Implements SimPy Processes, Resources, Buffers, and the backbone simulation
    scheduling by coroutine calls. Provides data collection through classes
    Monitor and Tally.
    Based on generators (Python 2.3 and later; not 3.0)

    LICENSE:
    Copyright (C) 2002, 2005, 2006, 2007, 2008  Klaus G. Muller, Tony Vignaux
    mailto: kgmuller@xs4all.nl and Tony.Vignaux@vuw.ac.nz

        This library is free software; you can redistribute it and / or
        modify it under the terms of the GNU Lesser General Public
        License as published by the Free Software Foundation; either
        version 2.1 of the License, or (at your option) any later version.

        This library is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        Lesser General Public License for more details.

        You should have received a copy of the GNU Lesser General Public
        License along with this library; if not, write to the Free Software
        Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111 - 1307  USA
    END OF LICENSE

    **Change history:**

        Started out as SiPy 0.9

        5 / 9/2002: SiPy 0.9.1

            - Addition of '_cancel' method in class Process and supporting '_unpost' method in
              class _Evlist.

            - Removal of redundant 'Action' method in class Process.

        12 / 9/2002:

            - Addition of resource class

            - Addition of '_request' and '_release' coroutine calls

        15 / 9/2002: moved into SimPy package

        16 / 9/2002:
            - Resource attributes fully implemented (resources can now have more
              than 1 shareable resource units)

        17 / 9/2002:

            - corrected removal from waitQ (Vignaux)

        17 / 9/2002:

            - added test for queue discipline in 'test_demo()'. Must be FIFO

        26 / 9/02: Version 0.2.0

            - cleaned up code; more consistent naming

            - prefixed all Simulation - private variable names with '_'.

            - prefixed all class - private variable names with '__'.

            - made normal exit quiet (but return message from scheduler()

        28 / 9/02:

            - included stopSimulation()

        15 / 10 / 02: Simulation version 0.3

            - Version printout now only if __TESTING

            - '_stop' initialized to True by module load, and set to False in
          initialize()

            - Introduced 'simulate(until = 0)' instead of 'scheduler(till = 0)'.
          Left 'scheduler()' in for backward compatibility, but marked
          as deprecated.

            - Added attribute 'name' to class Process; default == 'a_process'

            - Changed Resource constructor to
          'def __init__(self, capacity = 1, name = 'a_resource', unitName = 'units''.

        13 / 11 / 02: Simulation version 0.6

            - Major changes to class Resource:

                - Added two queue types for resources, FIFO (default) and PriorityQ

                - Changed constructor to allow selection of queue type.

                - Introduced preemption of resources (to be used with PriorityQ
                  queue type)

                - Changed constructor of class Resource to allow selection of preemption

                - Changes to class Process to support preemption of service

                - Cleaned up 'simulate' by replacing series of if - statements by dispatch table.

        19 / 11 / 02: Simulation version 0.6.1
            - Changed priority schemes so that higher values of Process
              attribute 'priority' represent higher priority.

        20 / 11 / 02: Simulation version 0.7
            - Major change of priority approach:

                - Priority set by 'yield request, self, res, priority'

                - Priority of a Process instance associated with a specific
                  resource

        25 / 11 / 02: Simulation version 0.7.1

            - Code cleanup and optimization

            - Made process attributes remainService and preempted private
             (_remainService and _preempted)

        11 / 12 / 2002: First process interrupt implementation

            - Addition of user methods 'interrupt' and 'resume'

            - Significant code cleanup to maintain process state

        20 / 12 / 2002: Changes to 'interrupt'; addition of boolean methods to show
                         process states

        16 / 3/2003: Changed hold (allowing posting events past _endtime)

        18 / 3/2003: Changed _nextev to prevent _t going past _endtime

        23 / 3/2003: Introduced new interrupt construct; deleted 'resume' method

        25 / 3/2003: Expanded interrupt construct:

            - Made 'interrupt' a method  of Process

            - Added 'interruptCause' as an attribute of an interrupted process

            - Changed definition of 'active' to
             'self._nextTime <> None and not self._inInterrupt'

            - Cleaned up test_interrupt function

        30 / 3/2003: Modification of 'simulate':

            - error message if 'initialize' not called (fatal)

            - error message if no process scheduled (warning)

            - Ensured that upon exit from 'simulate', now() == _endtime is
              always valid

        2 / 04 / 2003:

            - Modification of 'simulate': leave _endtime alone (undid change
              of 30 Mar 03)

            - faster '_unpost'

        3 / 04 / 2003: Made 'priority' private ('_priority')

        4 / 04 / 2003: Catch activation of non - generator error

        5 / 04 / 2003: Added 'interruptReset()' function to Process.

        7 / 04 / 2003: Changed '_unpost' to ensure that process has
                       _nextTime == None (is passive) afterwards.

        8 / 04 / 2003: Changed _hold to allow for 'yield hold, self'
                       (equiv to 'yield hold, self, 0')

        10 / 04 / 2003: Changed 'cancel' syntax to 'Process().cancel(victim)'

        12 / 5/2003: Changed eventlist handling from dictionary to bisect

        9 / 6/2003: - Changed eventlist handling from pure dictionary to bisect-
                    sorted 'timestamps' list of keys, resulting in greatly
                    improved performance for models with large
                    numbers of event notices with differing event times.
                    =========================================================
                    This great change was suggested by Prof. Simon Frost.
                    Thank you, Simon! This version 1.3 is dedicated to you!
                    =========================================================
                  - Added import of Lister which supports well - structured
                    printing of all attributes of Process and Resource instances.

        Oct 2003: Added monitored Resource instances (Monitors for activeQ and waitQ)

        13 Dec 2003: Merged in Monitor and Histogram

        27 Feb 2004: Repaired bug in activeQ monitor of class Resource. Now actMon
                     correctly records departures from activeQ.

        19 May 2004: Added erroneously omitted Histogram class.

        5 Sep 2004: Added SimEvents synchronization constructs

        17 Sep 2004: Added waituntil synchronization construct

        01 Dec 2004: SimPy version 1.5
                     Changes in this module: Repaired SimEvents bug re proc.eventsFired

        12 Jan 2005: SimPy version 1.5.1
                     Changes in this module: Monitor objects now have a default name
                                             'a_Monitor'

        29 Mar 2005: Start SimPy 1.6: compound 'yield request' statements

        05 Jun 2005: Fixed bug in _request method -- waitMon did not work properly in
                     preemption case

        09 Jun 2005: Added test in 'activate' to see whether 'initialize()' was called first.

        23 Aug 2005: - Added Tally data collection class
                     - Adjusted Resource to work with Tally
                     - Redid function allEventNotices() (returns prettyprinted string with event
                       times and names of process instances
                     - Added function allEventTimes (returns event times of all scheduled events)

        16 Mar 2006: - Added Store and Level classes
                     - Added 'yield get' and 'yield put'

        10 May 2006: - Repaired bug in Store._get method
                     - Repaired Level to allow initialBuffered have float value
                     - Added type test for Level get parameter 'nrToGet'

        06 Jun 2006: - To improve pretty - printed output of 'Level' objects, changed attribute
                       _nrBuffered to nrBuffered (synonym for amount property)
                     - To improve pretty - printed output of 'Store' objects, added attribute
                       buffered (which refers to _theBuffer)

        25 Aug 2006: - Start of version 1.8
                     - made 'version' public
                     - corrected condQ initialization bug

        30 Sep 2006: - Introduced checks to ensure capacity of a Buffer > 0
                     - Removed from __future__ import (so Python 2.3 or later needed)

        15 Oct 2006: - Added code to register all Monitors and all Tallies in variables
                       'allMonitors' and 'allTallies'
                     - Added function 'startCollection' to activate Monitors and Tallies at a
                       specified time (e.g. after warmup period)
                     - Moved all test / demo programs to after 'if __name__ == '__main__':'.

        17 Oct 2006: - Added compound 'put' and 'get' statements for Level and Store.

        18 Oct 2006: - Repaired bug: self.eventsFired now gets set after an event fires
                       in a compound yield get / put with a waitevent clause (reneging case).

        21 Oct 2006: - Introduced Store 'yield get' with a filter function.

        22 Oct 2006: - Repaired bug in prettyprinting of Store objects (the buffer
                       content==._theBuffer was not shown) by changing ._theBuffer
                       to .theBuffer.

        04 Dec 2006: - Added printHistogram method to Tally and Monitor (generates
                       table - form histogram)

        07 Dec 2006: - Changed the __str__ method of Histogram to print a table
                       (like printHistogram).

        18 Dec 2006: - Added trace printing of Buffers' 'unitName' for yield get and put.

        09 Jun 2007: - Cleaned out all uses of 'object' to prevent name clash.

        18 Nov 2007: - Start of 1.9 development
                     - Added 'start' method (alternative to activate) to Process

        22 Nov 2007: - Major change to event list handling to speed up larger models:
                        * Drop dictionary
                        * Replace bisect by heapq
                        * Mark cancelled event notices in unpost and skip them in
                          nextev (great idea of Tony Vignaux))

        4 Dec 2007: - Added twVariance calculation for both Monitor and Tally (gav)

        5 Dec 2007: - Changed name back to timeVariance (gav)

        1 Mar 2008: - Start of 1.9.1 bugfix release
                    - Delete circular reference in Process instances when event
                      notice has been processed (caused much circular garbage)
                    - Added capability for multiple preempts of a process

        10 Aug 2008: - Introduced a Simulation class that now contains all global
                       functions for the simulation.
                        * Globals.py contains dummies for them to obtain backward
                          compatibility (Ontje Luensdorf)
                     - Histogram, Monitor and Tally were moved to Recording.py
                       (Stefan Scherfke)
                     - Process, SimEvent, Queue, FIFO, PriorityQ, Resource, Buffer,
                       Level, Store moved to Resources.py
                     - Renamed __Evlist to Evlist

Version: 2.0 $Revision: 163 $ $Date: 2008-12-15 12:47:44 +0100 (Mo, 15 Dez 2008) $

Classes | [hide private]

| Simerror
| FatalSimerror
| Evlist Defines event list and operations on it
| Simulation

Functions | [hide private]

scheduler(till=0) Schedules Processes / semi - coroutines until time 'till'. | source code

holdfunc(a) | source code

requestfunc(a) Handles 'yield request, self, res' and 'yield (request, self, res),(<code>,self, par)'. | source code

releasefunc(a) | source code

passivatefunc(a) | source code

waitevfunc(a) | source code

queueevfunc(a) | source code

waituntilfunc(par) | source code

getfunc(a) Handles 'yield get, self, buffer, what, priority' and 'yield (get, self, buffer, what, priority),(<code>,self, par)'. | source code

putfunc(a) Handles 'yield put' (simple and compound hold / waitevent) | source code

Variables | [hide private]

| __TESTING = `False`
| version = ``'``2.0 $Revision: 163 $ $Date: 2008-12-15 12:47:44 +01``...``
| hold = `1`
| passivate = `2`
| request = `3`
| release = `4`
| waitevent = `5`
| queueevent = `6`
| waituntil = `7`
| get = `8`
| put = `9`
| __package__ = ``'``SimPy``'``

Function Details | [hide private]

### scheduler(till=0)

source code

Schedules Processes / semi - coroutines until time 'till'. Deprecated since version 0.5.

### requestfunc(a)

source code

Handles 'yield request, self, res' and 'yield (request, self, res),(<code>,self, par)'. <code > can be 'hold' or 'waitevent'.

### getfunc(a)

source code

Handles 'yield get, self, buffer, what, priority' and 'yield (get, self, buffer, what, priority),(<code>,self, par)'. <code > can be 'hold' or 'waitevent'.

Variables Details | [hide private]

### version

Value:

      '2.0 $Revision: 163 $ $Date: 2008-12-15 12:47:44 +0100 (Mo, 15 Dez 200
      8) $'