##################################################
# SPYCE - Python-based HTML Scripting
# Copyright (c) 2002 Rimon Barr.
#
# Refer to spyce.py
# CVS: $Id: pool.py 799 2005-07-22 02:19:19Z jbe $
##################################################

import sys, time, os.path
import cPickle as pickle
import spyce, spyceLock, spyceUtil
from spyceModule import spyceModule

__doc__ = """Pool module supports the creation of server-pooled objects. The
single pool is shared among all Spyce execution context residing on a given
server, and remains until the server dies. It is often useful to store
database connections, and other variables that are expensive to compute on a
per-request basis. """

# todo: should pickle/unpickle go somewhere else, such as request?
# this would make it more intuitive for people using SPYCE_GLOBALS
# but not pool module
def picklefile():
  return os.path.join(spyce.getServer().config.tmp, 'spypool.pickle')

class pool(spyceModule):
  def start(self):
    "Define or retrieve the pool."
    if spyce.getServer().threaded():
      self._pool = self._api.getServerGlobals()
      return
    try:
      f = open(picklefile(), 'rb')
    except IOError:
      self._pool = {}
      return
    def foo():
      spyceLock.file_lock(f, spyceLock.LOCK_SH | spyceLock.LOCK_NB)
      return True
    if not spyceUtil.tryForAwhile(foo):
      raise "timeout opening pool pickle file for read"
    try:
      try:
        self._pool = pickle.load(f)
      except EOFError, pickle.UnpicklingError:
        spyce.DEBUG("Warning: unable to complete loading pool from pickle file.  A common cause is adding instances of custom classes to the pool.  Consider using Spyce in standalone mode to avoid pickle-related limitations.")
        self._pool = {}
    finally:
      spyceLock.file_unlock(f)
      f.close()
  def finish(self, err):
    if spyce.getServer().threaded():
      return
    f = open(picklefile(), 'wb')
    def foo():
      spyceLock.file_lock(f, spyceLock.LOCK_EX | spyceLock.LOCK_NB)
      return True
    if not spyceUtil.tryForAwhile(foo):
      raise "timeout opening pool pickle file for write"
    try:
      pickle.dump(self._pool, f, -1)
    finally:
      spyceLock.file_unlock(f)
      f.close()
  def __getitem__(self, key):
    "Get an item from the pool."
    return self._pool[key]
  def __setitem__(self, key, value):
    "Set an item in the pool."
    self._pool[key] = value
  def __delitem__(self, key):
    "Delete an item in the pool."
    del self._pool[key]
  def keys(self):
    "Return the pool hash keys."
    return self._pool.keys()
  def values(self):
    "Return the pool hash values."
    return self._pool.values()
  def has_key(self, key):
    "Test of existence of key in pool."
    return self._pool.has_key(key)
  def __contains__(self, key):
    return key in self._pool
  def setdefault(self, *args, **kwargs):
    return self._pool.setdefault(*args, **kwargs)
  def items(self):
    return self._pool.items()
  def clear(self):
    "Purge the pool of all items."
    return self._pool.clear()