Source code for rwlock.service

"""
Module **rwlock.service** has class ``Service``, which is the concrete
version of the read-write-lock service program.
"""
from sesf.rwlock.serviceparts import ServiceParts
from threading import Thread, Lock, Condition, get_ident
from time import sleep
from random import random
import argparse, Pyro4
from sesf.util.pyro import (start_pyrodaemon)

@Pyro4.expose
class Service():
  """
  Read-write lock service (concrete version).
  Should be accessed via RPC (Pyro4) for testing a rwlock user program.

  Maintains the following variables:

  - ``serviceparts`` (obj): read-write-lock serviceparts
  - ``lck``, ``cond``: lock and condition variable for atomicity of 
    call and return parts.
  - ``pyrodaemon``: Pyro4 daemon object for handling RPC calls

  Functions (all have random delays):

  - ``acqr()``: acquire a read lock; blocking.
  - ``relr()``: release a read lock; nonblocking.
  - ``acqw()``: acquire a write lock; blocking.
  - ``relw()``: release a write lock; nonblocking.
  """

  def __init__(self):
    self.serviceparts = ServiceParts()
    self.lck = Lock()
    self.cond = Condition(self.lck)
    # start pyrodaemon object and store reference in self.pyrodaemon
    Thread(name='pyrodaemon', target=start_pyrodaemon,
           args=(self, 'sesf.rwlock.service')).start()

  def acqr(self):
    print('acqr thread', get_ident())
    x = self.serviceparts
    ## validate input
    with self.cond:
      if not x.acqr_CIC():
        raise Exception('acqr CIC violated')
      x.acqr_CU()
      self.cond.notify_all()
    sleep(random()*1)
    ## do output
    with self.cond:
      while not x.acqr_ROC():
          self.cond.wait()
      x.acqr_RU()
      self.cond.notify_all()


  def relr(self):
    print('relr thread', get_ident())
    x = self.serviceparts
    ## validate input
    with self.cond:
      if not x.relr_CIC():
        raise Exception('relr CIC violated')
      x.relr_CU()
      self.cond.notify_all()
    sleep(random()*1)
    ## do output
    with self.cond:
      while not x.relr_ROC():
          self.cond.wait()
      x.relr_RU()
      self.cond.notify_all()


  def acqw(self):
    print('acqw thread', get_ident())
    x = self.serviceparts
    ## validate input
    with self.cond:
      if not x.acqw_CIC():
        raise Exception('acqw CIC violated')
      x.acqw_CU()
      self.cond.notify_all()
    sleep(random()*1)
    ## do output
    with self.cond:
      while not x.acqw_ROC():
          self.cond.wait()
      x.acqw_RU()
      self.cond.notify_all()


  def relw(self):
    print('relw thread', get_ident())
    x = self.serviceparts
    ## validate input
    with self.cond:
      if not x.relw_CIC():
        raise Exception('relw CIC violated')
      x.relw_CU()
      self.cond.notify_all()
    sleep(random()*1)
    ## do output
    with self.cond:
      while not x.relw_ROC():
          self.cond.wait()
      x.relw_RU()
      self.cond.notify_all()

  def __end__(self):
    self.pyrodaemon.shutdown()

### end class Service #################################

if __name__ == '__main__':
  print("starting sesf.rwlock.service", flush=True)
  service = Service()