##############################################################################
#
# Copyright (c) 2007 Nexedi SA and Contributors. All Rights Reserved.
#                    Vincent Pelletier <vincent@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 sys
import transaction
from DateTime import DateTime
from Shared.DC.ZRDB.Results import Results
from zLOG import LOG, TRACE, INFO, WARNING, ERROR, PANIC
from ZODB.POSException import ConflictError
from Products.CMFActivity.ActivityTool import (
  Message, MESSAGE_NOT_EXECUTED, MESSAGE_EXECUTED)
from Products.CMFActivity.ActiveObject import INVOKE_ERROR_STATE
from Products.CMFActivity.ActivityRuntimeEnvironment import (
  DEFAULT_MAX_RETRY, ActivityRuntimeEnvironment, getTransactionalVariable)
from Queue import Queue, VALIDATION_ERROR_DELAY, VALID, INVALID_PATH
from Products.CMFActivity.Errors import ActivityFlushError
 
def sort_message_key(message):
  # same sort key as in SQLBase.getMessageList
  return message.line.priority, message.line.date, message.uid
 
_DequeueMessageException = Exception()
 
# sqltest_dict ({'condition_name': <render_function>}) defines how to render
# condition statements in the SQL query used by SQLBase.getMessageList
def sqltest_dict():
  sqltest_dict = {}
  no_quote_type = int, float, long
  def _(name, column=None, op="="):
    if column is None:
      column = name
    column_op = "%s %s " % (column, op)
    def render(value, render_string):
      if isinstance(value, no_quote_type):
        return column_op + str(value)
      if isinstance(value, DateTime):
        value = value.toZone('UTC').ISO()
      if isinstance(value, basestring):
        return column_op + render_string(value)
      assert op == "=", value
      if value is None: # XXX: see comment in SQLBase._getMessageList
        return column + " IS NULL"
      for x in value:
        if isinstance(x, no_quote_type):
          render_string = str
        elif isinstance(x, DateTime):
          value = (x.toZone('UTC').ISO() for x in value)
        return "%s IN (%s)" % (column, ', '.join(map(render_string, value)))
      return "0"
    sqltest_dict[name] = render
  _('active_process_uid')
  _('group_method_id')
  _('method_id')
  _('path')
  _('processing')
  _('processing_node')
  _('serialization_tag')
  _('tag')
  _('to_date', column="date", op="<=")
  _('uid')
  return sqltest_dict
sqltest_dict = sqltest_dict()
 
class SQLBase(Queue):
  """
    Define a set of common methods for SQL-based storage of activities.
  """
 
  def getNow(self, context):
    """
      Return the current value for SQL server's NOW().
      Note that this value is not cached, and is not transactionnal on MySQL
      side.
    """
    result = context.SQLBase_getNow()
    assert len(result) == 1
    assert len(result[0]) == 1
    return result[0][0]
 
  def _getMessageList(self, activity_tool, offset=0, count=1000, src__=0, **kw):
    # XXX: Because most columns have NOT NULL constraint, conditions with None
    #      value should be ignored, instead of trying to render them
    #      (with comparisons with NULL).
    sql_connection = activity_tool.getPortalObject().cmf_activity_sql_connection
    q = sql_connection.sql_quote__
    if offset:
      limit = '\nLIMIT %d,%d' % (offset, sys.maxint if count is None else count)
    else:
      limit = '' if count is None else '\nLIMIT %d' % count
    sql = '\n  AND '.join(sqltest_dict[k](v, q) for k, v in kw.iteritems())
    sql = "SELECT * FROM %s%s\nORDER BY priority, date, uid%s" % (
      self.sql_table, sql and '\nWHERE ' + sql, limit)
    return sql if src__ else Results(sql_connection().query(sql, max_rows=0))
 
  def getMessageList(self, *args, **kw):
    result = self._getMessageList(*args, **kw)
    if type(result) is str: # src__ == 1
      return result,
    class_name = self.__class__.__name__
    return [Message.load(line.message,
                             activity=class_name,
                             uid=line.uid,
                             processing_node=line.processing_node,
                             retry=line.retry,
                             processing=line.processing)
      for line in result]
 
  def _getPriority(self, activity_tool, method, default):
    result = method()
    if not result:
      return default
    assert len(result) == 1, len(result)
    return result[0]['priority']
 
  def _retryOnLockError(self, method, args=(), kw={}):
    while True:
      try:
        return method(*args, **kw)
      except ConflictError:
        # Note that this code assumes that a database adapter translates
        # a lock error into a conflict error.
        LOG('SQLBase', INFO, 'Got a lock error, retrying...')
 
  def _validate_after_method_id(self, activity_tool, message, value):
    return self._validate(activity_tool, method_id=value)
 
  def _validate_after_path(self, activity_tool, message, value):
    return self._validate(activity_tool, path=value)
 
  def _validate_after_message_uid(self, activity_tool, message, value):
    return self._validate(activity_tool, message_uid=value)
 
  def _validate_after_path_and_method_id(self, activity_tool, message, value):
    if not (isinstance(value, (tuple, list)) and len(value) == 2):
      LOG('CMFActivity', WARNING,
          'unable to recognize value for after_path_and_method_id: %r' % (value,))
      return []
    return self._validate(activity_tool, path=value[0], method_id=value[1])
 
  def _validate_after_tag(self, activity_tool, message, value):
    return self._validate(activity_tool, tag=value)
 
  def _validate_after_tag_and_method_id(self, activity_tool, message, value):
    # Count number of occurances of tag and method_id
    if not (isinstance(value, (tuple, list)) and len(value) == 2):
      LOG('CMFActivity', WARNING,
          'unable to recognize value for after_tag_and_method_id: %r' % (value,))
      return []
    return self._validate(activity_tool, tag=value[0], method_id=value[1])
 
  def _validate_serialization_tag(self, activity_tool, message, value):
    return self._validate(activity_tool, serialization_tag=value)
 
  def _log(self, severity, summary):
    LOG(self.__class__.__name__, severity, summary,
        error=severity>INFO and sys.exc_info() or None)
 
  def getReservedMessageList(self, activity_tool, date, processing_node,
                             limit=None, group_method_id=None):
    """
      Get and reserve a list of messages.
      limit
        Maximum number of messages to fetch.
        This number is not garanted to be reached, because of:
         - not enough messages being pending execution
         - race condition (other nodes reserving the same messages at the same
           time)
        This number is guaranted not to be exceeded.
        If None (or not given) no limit apply.
    """
    assert limit
    # Do not check already-assigned messages when trying to reserve more
    # activities, because in such case we will find one reserved activity.
    result = activity_tool.SQLBase_selectReservedMessageList(
      table=self.sql_table,
      count=limit,
      processing_node=processing_node,
      group_method_id=group_method_id,
    )
    limit -= len(result)
    if limit:
      reservable = activity_tool.SQLBase_getReservableMessageList(
        table=self.sql_table,
        count=limit,
        processing_node=processing_node,
        to_date=date,
        group_method_id=group_method_id,
      )
      if reservable:
        activity_tool.SQLBase_reserveMessageList(
          uid=[x.uid for x in reservable],
          table=self.sql_table,
          processing_node=processing_node,
        )
        # DC.ZRDB.Results.Results does not implement concatenation
        # Implement an imperfect (but cheap) concatenation. Do not update
        # __items__ nor _data_dictionary.
        assert result._names == reservable._names, (result._names,
          reservable._names)
        result._data += reservable._data
    return result
 
  def makeMessageListAvailable(self, activity_tool, uid_list):
    """
      Put messages back in processing_node=0 .
    """
    if len(uid_list):
      activity_tool.SQLBase_makeMessageListAvailable(table=self.sql_table,
                                                     uid=uid_list)
 
  def getProcessableMessageLoader(self, activity_tool, processing_node):
    # do not merge anything
    def load(line):
      uid = line.uid
      m = Message.load(line.message, uid=uid, line=line)
      return m, uid, ()
    return load
 
  def getProcessableMessageList(self, activity_tool, processing_node):
    """
      Always true:
        For each reserved message, delete redundant messages when it gets
        reserved (definitely lost, but they are expandable since redundant).
 
      - reserve a message
      - set reserved message to processing=1 state
      - if this message has a group_method_id:
        - reserve a bunch of messages
        - until the total "cost" of the group goes over 1
          - get one message from the reserved bunch (this messages will be
            "needed")
          - update the total cost
        - set "needed" reserved messages to processing=1 state
        - unreserve "unneeded" messages
      - return still-reserved message list and a group_method_id
 
      If any error happens in above described process, try to unreserve all
      messages already reserved in that process.
      If it fails, complain loudly that some messages might still be in an
      unclean state.
 
      Returned values:
        4-tuple:
          - list of messages
          - group_method_id
          - uid_to_duplicate_uid_list_dict
    """
    def getReservedMessageList(limit, group_method_id=None):
      line_list = self.getReservedMessageList(activity_tool=activity_tool,
                                              date=now_date,
                                              processing_node=processing_node,
                                              limit=limit,
                                              group_method_id=group_method_id)
      if line_list:
        self._log(TRACE, 'Reserved messages: %r' % [x.uid for x in line_list])
      return line_list
    now_date = self.getNow(activity_tool)
    uid_to_duplicate_uid_list_dict = {}
    try:
      result = getReservedMessageList(1)
      if result:
        load = self.getProcessableMessageLoader(activity_tool, processing_node)
        m, uid, uid_list = load(result[0])
        message_list = [m]
        uid_to_duplicate_uid_list_dict[uid] = uid_list
        group_method_id = m.line.group_method_id
        if group_method_id != '\0':
          # Count the number of objects to prevent too many objects.
          cost = m.activity_kw.get('group_method_cost', .01)
          assert 0 < cost <= 1, (self.sql_table, uid)
          count = m.getObjectCount(activity_tool)
          # this is heuristic (messages with same group_method_id
          # are likely to have the same group_method_cost)
          limit = int(1. / cost + 1 - count)
          if limit > 1: # <=> cost * count < 1
            cost *= count
            # Retrieve objects which have the same group method.
            result = iter(getReservedMessageList(limit, group_method_id))
            for line in result:
              if line.uid in uid_to_duplicate_uid_list_dict:
                continue
              m, uid, uid_list = load(line)
              if m is None:
                uid_to_duplicate_uid_list_dict[uid] += uid_list
                continue
              uid_to_duplicate_uid_list_dict[uid] = uid_list
              cost += m.getObjectCount(activity_tool) * \
                      m.activity_kw.get('group_method_cost', .01)
              message_list.append(m)
              if cost >= 1:
                # Unreserve extra messages as soon as possible.
                self.makeMessageListAvailable(activity_tool=activity_tool,
                  uid_list=[line.uid for line in result if line.uid != uid])
        activity_tool.SQLBase_processMessage(table=self.sql_table,
          uid=uid_to_duplicate_uid_list_dict.keys())
        return message_list, group_method_id, uid_to_duplicate_uid_list_dict
    except:
      self._log(WARNING, 'Exception while reserving messages.')
      if uid_to_duplicate_uid_list_dict:
        to_free_uid_list = uid_to_duplicate_uid_list_dict.keys()
        for uid_list in uid_to_duplicate_uid_list_dict.itervalues():
          to_free_uid_list += uid_list
        try:
          self.makeMessageListAvailable(activity_tool=activity_tool,
                                        uid_list=to_free_uid_list)
        except:
          self._log(ERROR, 'Failed to free messages: %r' % to_free_uid_list)
        else:
          if to_free_uid_list:
            self._log(TRACE, 'Freed messages %r' % to_free_uid_list)
      else:
        self._log(TRACE, '(no message was reserved)')
    return [], None, uid_to_duplicate_uid_list_dict
 
  def _abort(self):
    try:
      transaction.abort()
    except:
      # Unfortunately, database adapters may raise an exception against abort.
      self._log(PANIC,
          'abort failed, thus some objects may be modified accidentally')
      raise
 
  # Queue semantic
  def dequeueMessage(self, activity_tool, processing_node):
    message_list, group_method_id, uid_to_duplicate_uid_list_dict = \
      self.getProcessableMessageList(activity_tool, processing_node)
    if message_list:
      # Remove group_id parameter from group_method_id
      if group_method_id is not None:
        group_method_id = group_method_id.split('\0')[0]
      if group_method_id not in (None, ""):
        method  = activity_tool.invokeGroup
        args = (group_method_id, message_list, self.__class__.__name__,
                hasattr(self, 'generateMessageUID'))
        activity_runtime_environment = ActivityRuntimeEnvironment(None)
      else:
        method = activity_tool.invoke
        message = message_list[0]
        args = (message, )
        activity_runtime_environment = ActivityRuntimeEnvironment(message)
      # Commit right before executing messages.
      # As MySQL transaction does not start exactly at the same time as ZODB
      # transactions but a bit later, messages available might be called
      # on objects which are not available - or available in an old
      # version - to ZODB connector.
      # So all connectors must be committed now that we have selected
      # everything needed from MySQL to get a fresh view of ZODB objects.
      transaction.commit()
      transaction.begin()
      tv = getTransactionalVariable()
      tv['activity_runtime_environment'] = activity_runtime_environment
      # Try to invoke
      try:
        method(*args)
        # Abort if at least 1 message failed. On next tic, only those that
        # succeeded will be selected because their at_date won't have been
        # increased.
        for m in message_list:
          if m.getExecutionState() == MESSAGE_NOT_EXECUTED:
            raise _DequeueMessageException
        transaction.commit()
      except:
        exc_info = sys.exc_info()
        if exc_info[1] is not _DequeueMessageException:
          self._log(WARNING,
            'Exception raised when invoking messages (uid, path, method_id) %r'
            % [(m.uid, m.object_path, m.method_id) for m in message_list])
          for m in message_list:
            m.setExecutionState(MESSAGE_NOT_EXECUTED, exc_info, log=False)
        self._abort()
        exc_info = message_list[0].exc_info
        if exc_info:
          try:
            # Register it again.
            tv['activity_runtime_environment'] = activity_runtime_environment
            cancel = message.on_error_callback(*exc_info)
            del exc_info, message.exc_info
            transaction.commit()
            if cancel:
              message.setExecutionState(MESSAGE_EXECUTED)
          except:
            self._log(WARNING, 'Exception raised when processing error callbacks')
            message.setExecutionState(MESSAGE_NOT_EXECUTED)
            self._abort()
      self.finalizeMessageExecution(activity_tool, message_list,
                                    uid_to_duplicate_uid_list_dict)
    transaction.commit()
    return not message_list
 
  def finalizeMessageExecution(self, activity_tool, message_list,
                               uid_to_duplicate_uid_list_dict=None):
    """
      If everything was fine, delete all messages.
      If anything failed, make successful messages available (if any), and
      the following rules apply to failed messages:
        - Failures due to ConflictErrors cause messages to be postponed,
          but their retry count is *not* increased.
        - Failures of messages already above maximum retry count cause them to
          be put in a permanent-error state.
        - In all other cases, retry count is increased and message is delayed.
    """
    deletable_uid_list = []
    delay_uid_list = []
    final_error_uid_list = []
    make_available_uid_list = []
    notify_user_list = []
    executed_uid_list = deletable_uid_list
    if uid_to_duplicate_uid_list_dict is not None:
      for m in message_list:
        if m.getExecutionState() == MESSAGE_NOT_EXECUTED:
          executed_uid_list = make_available_uid_list
          break
    for m in message_list:
      uid = m.uid
      if m.getExecutionState() == MESSAGE_EXECUTED:
        executed_uid_list.append(uid)
        if uid_to_duplicate_uid_list_dict is not None:
          executed_uid_list += uid_to_duplicate_uid_list_dict.get(uid, ())
      elif m.getExecutionState() == MESSAGE_NOT_EXECUTED:
        # Should duplicate messages follow strictly the original message, or
        # should they be just made available again ?
        if uid_to_duplicate_uid_list_dict is not None:
          make_available_uid_list += uid_to_duplicate_uid_list_dict.get(uid, ())
        if (m.exc_type and # m.exc_type may be None
            m.conflict_retry and issubclass(m.exc_type, ConflictError)):
          delay_uid_list.append(uid)
        else:
          max_retry = m.max_retry
          retry = m.line.retry
          if max_retry is not None and retry >= max_retry:
            # Always notify when we stop retrying.
            notify_user_list.append((m, False))
            final_error_uid_list.append(uid)
            continue
          # In case of infinite retry, notify the user
          # when the default limit is reached.
          if max_retry is None and retry == DEFAULT_MAX_RETRY:
            notify_user_list.append((m, True))
          delay = m.delay
          if delay is None:
            # By default, make delay quadratic to the number of retries.
            delay = VALIDATION_ERROR_DELAY * (retry * retry + 1) / 2
          try:
            # Immediately update, because values different for every message
            activity_tool.SQLBase_reactivate(table=self.sql_table,
                                             uid=[uid],
                                             delay=delay,
                                             retry=1)
          except:
            self._log(WARNING, 'Failed to reactivate %r' % uid)
        make_available_uid_list.append(uid)
      else: # MESSAGE_NOT_EXECUTABLE
        # 'path' does not point to any object. Activities are normally flushed
        # (without invoking them) when an object is deleted, but this is only
        # an optimisation. There is no efficient and reliable way to do such
        # this, because a concurrent and very long transaction may be about to
        # activate this object, without conflict.
        # So we have to clean up any remaining activity.
        deletable_uid_list.append(uid)
    if deletable_uid_list:
      try:
        self._retryOnLockError(activity_tool.SQLBase_delMessage,
                               kw={'table': self.sql_table,
                                   'uid': deletable_uid_list})
      except:
        self._log(ERROR, 'Failed to delete messages %r' % deletable_uid_list)
      else:
        self._log(TRACE, 'Deleted messages %r' % deletable_uid_list)
    if delay_uid_list:
      try:
        # If this is a conflict error, do not increase 'retry' but only delay.
        activity_tool.SQLBase_reactivate(table=self.sql_table,
          uid=delay_uid_list, delay=VALIDATION_ERROR_DELAY, retry=None)
      except:
        self._log(ERROR, 'Failed to delay %r' % delay_uid_list)
    if final_error_uid_list:
      try:
        activity_tool.SQLBase_assignMessage(table=self.sql_table,
          uid=final_error_uid_list, processing_node=INVOKE_ERROR_STATE)
      except:
        self._log(ERROR, 'Failed to set message to error state for %r'
                         % final_error_uid_list)
    if make_available_uid_list:
      try:
        self.makeMessageListAvailable(activity_tool=activity_tool,
                                      uid_list=make_available_uid_list)
      except:
        self._log(ERROR, 'Failed to unreserve %r' % make_available_uid_list)
      else:
        self._log(TRACE, 'Freed messages %r' % make_available_uid_list)
    try:
      for m, retry in notify_user_list:
        m.notifyUser(activity_tool, retry)
    except:
      # Notification failures must not cause this method to raise.
      self._log(WARNING,
        'Exception during notification phase of finalizeMessageExecution')
 
  def flush(self, activity_tool, object_path, invoke=0, method_id=None, **kw):
    """
      object_path is a tuple
    """
    path = '/'.join(object_path)
    if invoke:
      invoked = set()
      def invoke(message):
        try:
          key = self.generateMessageUID(message)
          if key in invoked:
            return
          invoked.add(key)
        except AttributeError:
          pass
        line = getattr(message, 'line', None)
        validate_value = VALID if line and line.processing_node != -1 else \
                         message.validate(self, activity_tool)
        if validate_value == VALID:
          # Try to invoke the message - what happens if invoke calls flushActivity ??
          activity_tool.invoke(message)
          if message.getExecutionState() != MESSAGE_EXECUTED:
            raise ActivityFlushError('Could not invoke %s on %s'
                                     % (message.method_id, path))
        elif validate_value is INVALID_PATH:
          raise ActivityFlushError('The document %s does not exist' % path)
        else:
          raise ActivityFlushError('Could not validate %s on %s'
                                   % (message.method_id, path))
    for m in activity_tool.getRegisteredMessageList(self):
      if object_path == m.object_path and (
         method_id is None or method_id == m.method_id):
        if invoke:
          invoke(m)
        activity_tool.unregisterMessage(self, m)
    uid_list = []
    for line in self._getMessageList(activity_tool, path=path, processing=0,
        **({'method_id': method_id} if method_id else {})):
      uid_list.append(line.uid)
      if invoke:
        invoke(Message.load(line.message, uid=line.uid, line=line))
    if uid_list:
      activity_tool.SQLBase_delMessage(table=self.sql_table, uid=uid_list)