SQLDict.py

##############################################################################
#
# 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 program is Free Software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
##############################################################################

import random
from DateTime import DateTime
from Products.CMFActivity.ActivityTool import registerActivity
from Queue import VALID, INVALID_ORDER, INVALID_PATH, EXCEPTION, MAX_PROCESSING_TIME, VALIDATION_ERROR_DELAY, SECONDS_IN_DAY
from RAMDict import RAMDict
from Products.CMFActivity.ActiveObject import DISTRIBUTABLE_STATE, INVOKE_ERROR_STATE, VALIDATE_ERROR_STATE

from zLOG import LOG

MAX_PRIORITY = 5

priority_weight = \
  [1] * 64 + \
  [2] * 20 + \
  [3] * 10 + \
  [4] * 5 + \
  [5] * 1

class ActivityFlushError(Exception):
    """Error during active message flush"""

class SQLDict(RAMDict):
  """
    A simple OOBTree based queue. It should be compatible with transactions
    and provide sequentiality. Should not create conflict
    because use of OOBTree.
  """
  # Transaction commit methods
  def prepareQueueMessage(self, activity_tool, m):
    if m.is_registered:
      activity_tool.SQLDict_writeMessage( path = '/'.join(m.object_path) ,
                                          method_id = m.method_id,
                                          priority = m.activity_kw.get('priority', 1),
                                          message = self.dumpMessage(m),
                                          date = m.activity_kw.get('at_date', DateTime()))
                                          # Also store uid of activity

  def prepareDeleteMessage(self, activity_tool, m):
    # Erase all messages in a single transaction
    path = '/'.join(m.object_path)
    uid_list = activity_tool.SQLDict_readUidList(path=path, method_id=m.method_id,processing_node=None)
    uid_list = map(lambda x:x.uid, uid_list)
    if len(uid_list)>0:
      activity_tool.SQLDict_delMessage(uid = uid_list) 
    
  # Registration management    
  def registerActivityBuffer(self, activity_buffer):
    class_name = self.__class__.__name__
    setattr(activity_buffer, '_%s_uid_dict' % class_name, {})  
    setattr(activity_buffer, '_%s_message_list' % class_name, [])  
            
  def isMessageRegistered(self, activity_buffer, activity_tool, m):
    class_name = self.__class__.__name__
    uid_dict = getattr(activity_buffer,'_%s_uid_dict' % class_name)
    return uid_dict.has_key((tuple(m.object_path), m.method_id))
          
  def registerMessage(self, activity_buffer, activity_tool, m):
    m.is_registered = 1
    class_name = self.__class__.__name__
    uid_dict = getattr(activity_buffer,'_%s_uid_dict' % class_name)
    uid_dict[(tuple(m.object_path), m.method_id)] = 1
    getattr(activity_buffer,'_%s_message_list' % class_name).append(m)
          
  def unregisterMessage(self, activity_buffer, activity_tool, m):
    m.is_registered = 0 # This prevents from inserting deleted messages into the queue
    class_name = self.__class__.__name__
    uid_dict = getattr(activity_buffer,'_%s_uid_dict' % class_name)
    if uid_dict.has_key((tuple(m.object_path), m.method_id)):
      del uid_dict[(tuple(m.object_path), m.method_id)]

  def getRegisteredMessageList(self, activity_buffer, activity_tool):
    class_name = self.__class__.__name__
    if hasattr(activity_buffer,'_%s_message_list' % class_name):
      message_list = getattr(activity_buffer,'_%s_message_list' % class_name)
      return filter(lambda m: m.is_registered, message_list)
    else:
      return ()
                
  # Queue semantic
  def dequeueMessage(self, activity_tool, processing_node):
    if hasattr(activity_tool,'SQLDict_readMessage'):
      now_date = DateTime()
      # Sticky processing messages should be set back to non processing
      max_processing_date = now_date - MAX_PROCESSING_TIME
      # Next processing date in case of error
      next_processing_date = now_date + VALIDATION_ERROR_DELAY
      priority = random.choice(priority_weight)
      # Try to find a message at given priority level which is scheduled for now
      result = activity_tool.SQLDict_readMessage(processing_node=processing_node, priority=priority,
                                                 to_date=now_date, to_processing_date = max_processing_date)
      if len(result) == 0:
        # If empty, take any message which is scheduled for now
        priority = None
        result = activity_tool.SQLDict_readMessage(processing_node=processing_node, priority=priority, to_date=now_date)
      if len(result) > 0:
        line = result[0]
        path = line.path
        method_id = line.method_id
        uid_list = activity_tool.SQLDict_readUidList( path=path, method_id= method_id, processing_node = None, to_date=now_date )
        uid_list = map(lambda x:x.uid, uid_list)
        # Make sure message can not be processed anylonger
        if len(uid_list) > 0:
          # Set selected messages to processing          
          activity_tool.SQLDict_processMessage(uid = uid_list)
        get_transaction().commit() # Release locks before starting a potentially long calculation
        # This may lead (1 for 1,000,000 in case of reindexing) to messages left in processing state
        m = self.loadMessage(line.message, uid = line.uid)
        # Validate message (make sure object exists, priority OK, etc.)
        validation_state = m.validate(self, activity_tool)
        if validation_state is not VALID:
          if validation_state in (EXCEPTION, INVALID_PATH):          
            # There is a serious validation error - we must lower priority
            if line.priority > MAX_PRIORITY:
              # This is an error
              if len(uid_list) > 0: 
                activity_tool.SQLDict_assignMessage(uid = uid_list, processing_node = VALIDATE_ERROR_STATE)
                                                                                # Assign message back to 'error' state
              #m.notifyUser(activity_tool)                                      # Notify Error
              get_transaction().commit()                                        # and commit
            else:
              # Lower priority
              if len(uid_list) > 0: # Add some delay before new processing
                activity_tool.SQLDict_setPriority(uid = uid_list, date = next_processing_date,
                                                  priority = line.priority + 1)
              get_transaction().commit() # Release locks before starting a potentially long calculation
          else:
            # We do not lower priority for INVALID_ORDER errors but we do postpone execution
            if len(uid_list) > 0: # Add some delay before new processing
              activity_tool.SQLDict_setPriority(uid = uid_list, date = next_processing_date,
                                                priority = line.priority)
            get_transaction().commit() # Release locks before starting a potentially long calculation
        else:
          # Try to invoke
          activity_tool.invoke(m) # Try to invoke the message - what happens if read conflict error restarts transaction ?
          if m.is_executed:                                          # Make sure message could be invoked
            if len(uid_list) > 0:
              activity_tool.SQLDict_delMessage(uid = uid_list)                # Delete it
            get_transaction().commit()                                        # If successful, commit
            if m.active_process:
              active_process = activity_tool.unrestrictedTraverse(m.active_process)
              if not active_process.hasActivity():
                # Not more activity
                m.notifyUser(activity_tool, message="Process Finished") # XXX commit bas ???
          else:
            get_transaction().abort()                                         # If not, abort transaction and start a new one
            if line.priority > MAX_PRIORITY:
              # This is an error
              if len(uid_list) > 0:
                activity_tool.SQLDict_assignMessage(uid = uid_list, processing_node = INVOKE_ERROR_STATE)
                                                                                # Assign message back to 'error' state
              m.notifyUser(activity_tool)                                       # Notify Error
              get_transaction().commit()                                        # and commit
            else:
              # Lower priority
              if len(uid_list) > 0:
                activity_tool.SQLDict_setPriority(uid = uid_list, date = next_processing_date,
                                                  priority = line.priority + 1)
              get_transaction().commit() # Release locks before starting a potentially long calculation
        return 0
      get_transaction().commit() # Release locks before starting a potentially long calculation
    return 1

  def hasActivity(self, activity_tool, object, **kw):
    if hasattr(activity_tool,'SQLDict_readMessageList'):
      if object is not None:
        my_object_path = '/'.join(object.getPhysicalPath())
        result = activity_tool.SQLDict_hasMessage(path=my_object_path, **kw)
        if len(result) > 0:
          return result[0].message_count > 0
      else:
        return 1 # Default behaviour if no object specified is to return 1 until active_process implemented
    return 0

  def flush(self, activity_tool, object_path, invoke=0, method_id=None, commit=0, **kw):
    """
      object_path is a tuple

      commit allows to choose mode
        - if we commit, then we make sure no locks are taken for too long
        - if we do not commit, then we can use flush in a larger transaction

      commit should in general not be used

      NOTE: commiting is very likely nonsenses here. We should just avoid to flush as much as possible
    """
    path = '/'.join(object_path)
    # LOG('Flush', 0, str((path, invoke, method_id)))
    method_dict = {}
    if hasattr(activity_tool,'SQLDict_readMessageList'):
      # Parse each message in registered
      for m in activity_tool.getRegisteredMessageList(self):
        if list(m.object_path) == list(object_path) and (method_id is None or method_id == m.method_id):
          activity_tool.unregisterMessage(self, m)
          #if not method_dict.has_key(method_id or m.method_id):
          if not method_dict.has_key(m.method_id):
            method_dict[m.method_id] = 1 # Prevents calling invoke twice
            if invoke:
              # First Validate
              if m.validate(self, activity_tool) is VALID:
                activity_tool.invoke(m) # Try to invoke the message - what happens if invoke calls flushActivity ??
                if not m.is_executed:                                                 # Make sure message could be invoked
                  # The message no longer exists
                  raise ActivityFlushError, (
                      'Could not evaluate %s on %s' % (m.method_id , path))
              else:
                # The message no longer exists
                raise ActivityFlushError, (
                    'The document %s does not exist' % path)               
      # Parse each message in SQL dict
      result = activity_tool.SQLDict_readMessageList(path=path, method_id=method_id,processing_node=None)
      for line in result:
        path = line.path
        method_id = line.method_id
        if not method_dict.has_key(method_id):
          # Only invoke once (it would be different for a queue)
          method_dict[method_id] = 1
          m = self.loadMessage(line.message, uid = line.uid)
          self.deleteMessage(activity_tool, m)
          if invoke:
            # First Validate
            if m.validate(self, activity_tool) is VALID:
              activity_tool.invoke(m) # Try to invoke the message - what happens if invoke calls flushActivity ??
              if not m.is_executed:                                                 # Make sure message could be invoked
                # The message no longer exists
                raise ActivityFlushError, (
                    'Could not evaluate %s on %s' % (m.method_id , path))
            else:
              # The message no longer exists
              raise ActivityFlushError, (
                  'The document %s does not exist' % path)

  def getMessageList(self, activity_tool, processing_node=None):
    # YO: reading all lines might cause a deadlock
    message_list = []
    if hasattr(activity_tool,'SQLDict_readMessageList'):
      result = activity_tool.SQLDict_readMessageList(path=None, method_id=None, processing_node=None)
      for line in result:
        m = self.loadMessage(line.message, uid = line.uid)
        m.processing_node = line.processing_node
        m.priority = line.priority
        message_list.append(m)
    return message_list

  def distribute(self, activity_tool, node_count):
    processing_node = 1
    if hasattr(activity_tool,'SQLDict_readMessageList'):
      result = activity_tool.SQLDict_readMessageList(path=None, method_id=None, processing_node = -1) # Only assign non assigned messages
      get_transaction().commit() # Release locks before starting a potentially long calculation
      path_dict = {}
      for line in result:
        path = line.path
        if not path_dict.has_key(path):
          # Only assign once (it would be different for a queue)
          path_dict[path] = 1
          activity_tool.SQLDict_assignMessage(path=path, processing_node=processing_node, uid=None)
          get_transaction().commit() # Release locks immediately to allow processing of messages
          processing_node = processing_node + 1
          if processing_node > node_count:
            processing_node = 1 # Round robin

  # Validation private methods
  def _validate_after_method_id(self, activity_tool, message, value):
    # Count number of occurances of method_id
    result = activity_tool.SQLDict_validateMessageList(method_id=value, message_uid=None, path=None)
    if result[0].uid_count > 0:
      return INVALID_ORDER
    return VALID
            
  def _validate_after_path(self, activity_tool, message, value):
    # Count number of occurances of path
    result = activity_tool.SQLDict_validateMessageList(method_id=None, message_uid=None, path=value)
    if result[0].uid_count > 0:
      return INVALID_ORDER
    return VALID
            
  def _validate_after_message_uid(self, activity_tool, message, value):
    # Count number of occurances of message_uid
    result = activity_tool.SQLDict_validateMessageList(method_id=None, message_uid=value, path=None)
    if result[0].uid_count > 0:
      return INVALID_ORDER
    return VALID

  # Required for tests (time shift)        
  def timeShift(self, activity_tool, delay):    
    """
      To simulate timeShift, we simply substract delay from
      all dates in SQLDict message table
    """
    activity_tool.SQLDict_timeShift(delay = delay * SECONDS_IN_DAY)
            
registerActivity(SQLDict)