ActivityBuffer.py

##############################################################################
#
# Copyright (c) 2001 Zope Corporation and Contributors. All Rights Reserved.
# Copyright (c) 2002 Nexedi SARL and Contributors. All Rights Reserved.
#          Jean-Paul Smets-Solanes <jp@nexedi.com>
#
# WARNING: This program as such is intended to be used by professional
# programmers who take the whole responsability of assessing all potential
# consequences resulting from its eventual inadequacies and bugs
# End users who are looking for a ready-to-use solution with commercial
# garantees and support are strongly adviced to contract a Free Software
# Service Company
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
#
# Based on: db.py in ZMySQLDA
#
##############################################################################

from Shared.DC.ZRDB.TM import TM
from zLOG import LOG, ERROR, INFO
import sys

class ActivityBuffer(TM):
    
    _p_oid=_p_changed=_registered=None
        
    def __init__(self):
        from thread import allocate_lock
        self._use_TM = self._transactions = 1
        if self._use_TM:
            self._tlock = allocate_lock()
            self._tthread = None
        self._lock = allocate_lock()
       
    # Keeps a list of messages to add and remove
    # at end of transaction
    def _begin(self, *ignored):
        from thread import get_ident
        from ActivityTool import activity_list
        self._tlock.acquire()
        self._tthread = get_ident()
        self.requires_prepare = 1
        try:
            self.queued_activity = []
            self.flushed_activity = []
            for activity in activity_list:              # Reset registration for each transaction
                activity.registerActivityBuffer(self)
        except:
            LOG('ActivityBuffer', ERROR, "exception during _begin",
                error=sys.exc_info())
            self._tlock.release()
            raise
        
    def _finish(self, *ignored):
        from thread import get_ident
        if not self._tlock.locked() or self._tthread != get_ident():
            LOG('ActivityBuffer', INFO, "ignoring _finish")
            return
        try:
            try:
                # Try to push / delete all messages
                for (activity, activity_tool, message) in self.flushed_activity:
                    #LOG('ActivityBuffer finishDeleteMessage', ERROR, str(message.method_id))
                    activity.finishDeleteMessage(activity_tool, message)
                for (activity, activity_tool, message) in self.queued_activity:
                    #LOG('ActivityBuffer finishQueueMessage', ERROR, str(message.method_id))
                    activity.finishQueueMessage(activity_tool, message)
            except:
                LOG('ActivityBuffer', ERROR, "exception during _finish",
                    error=sys.exc_info())
                raise
        finally:
            self._tlock.release()

    def _abort(self, *ignored):
        from thread import get_ident
        if not self._tlock.locked() or self._tthread != get_ident():
            LOG('ActivityBuffer', 0, "ignoring _abort")
            return
        self._tlock.release()

    def tpc_prepare(self, transaction, sub=None):
        if sub is not None: # Do nothing if it is a subtransaction
          return
        if not self.requires_prepare: return
        self.requires_prepare = 0
        from thread import get_ident
        if not self._tlock.locked() or self._tthread != get_ident():
            LOG('ActivityBuffer', 0, "ignoring tpc_prepare")
            return
        try:
            # Try to push / delete all messages
            for (activity, activity_tool, message) in self.flushed_activity:
                #LOG('ActivityBuffer prepareDeleteMessage', ERROR, str(message.method_id))
                activity.prepareDeleteMessage(activity_tool, message)
            for (activity, activity_tool, message) in self.queued_activity:
                #LOG('ActivityBuffer prepareQueueMessage', ERROR, str(message.method_id))
                activity.prepareQueueMessage(activity_tool, message)
        except:
            LOG('ActivityBuffer', ERROR, "exception during tpc_prepare",
                error=sys.exc_info())
            raise
                
    def deferredQueueMessage(self, activity_tool, activity, message):
      self._register()      
      # Activity is called to prevent queuing some messages (useful for example
      # to prevent reindexing objects multiple times)
      if not activity.isMessageRegistered(self, activity_tool, message):
        self.queued_activity.append((activity, activity_tool, message))
        # We register queued messages so that we can 
        # unregister them
        activity.registerMessage(self, activity_tool, message)
        
    def deferredDeleteMessage(self, activity_tool, activity, message):
      self._register()
      self.flushed_activity.append((activity, activity_tool, message))