~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2010 PrimeBase Technologies GmbH, Germany

 *

 *  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; version 2 of the License.

 *

 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * Barry Leslie

 *

 * 2010-05-12

 */

#include <config.h>

#include <string>

#include <vector>

#include <drizzled/session.h>

#include <drizzled/table_list.h>

#include <drizzled/table/instance.h>

#include <drizzled/module/registry.h>

#include <drizzled/plugin/event_observer.h>

#include <drizzled/util/functors.h>

#include <algorithm>

namespace drizzled {

namespace plugin {

  EventObserverVector all_event_plugins;

  const EventObserverVector &EventObserver::getEventObservers()

  {

    return all_event_plugins;

  }

  bool EventObserver::addPlugin(EventObserver *handler)

  {

    if (handler != NULL)

      all_event_plugins.push_back(handler);

    return false;

  }

  void EventObserver::removePlugin(EventObserver *handler)

  {

    if (handler != NULL)

      all_event_plugins.erase(std::find(all_event_plugins.begin(), all_event_plugins.end(), handler));

  }

  /* 

   * The Event Observer list class in which plugins register which events they

   * are interested in.

   *

   * Each table share for example, will have one of these hung on it to store

   * a list off all event observers interested in it and which events they are

   * interested in.

 */

  class EventObserverList

  {

  public:

    typedef std::multimap<uint32_t, EventObserver *> ObserverMap;

  private:

    /* A list of lists indexed by event type. */

    std::vector<ObserverMap *> event_observer_lists;

  public:

    EventObserverList()

    {

			// Initialize the list with NULL pointers.

			event_observer_lists.assign(EventObserver::MAX_EVENT_COUNT, NULL);

    }

    ~EventObserverList()

    {

      std::for_each(event_observer_lists.begin(),

                    event_observer_lists.end(),

                    DeletePtr());

      event_observer_lists.clear();

    }

    /* Add the observer to the observer list for the even, positioning it if required.

     *

     * Note: Event observers are storted in a multimap object so that the order in which

     * they are called can be sorted based on the requested position. Lookups are never done

     * on the multimap, once filled it is used as a vector.

   */

    void addObserver(EventObserver *eventObserver, enum EventObserver::EventType event, int32_t position)

    {

      uint32_t event_pos;

      ObserverMap *observers;

      observers= event_observer_lists[event];

      if (observers == NULL) 

      {

        observers= new ObserverMap();

        event_observer_lists[event]= observers;

      }

      if (position == 0)

        event_pos= INT32_MAX; // Set the event position to be in the middle.

      else

        event_pos= (uint32_t) position;

      /* If positioned then check if the position is already taken. */

      if (position) 

      {

        if (observers->count(event_pos))

        {

          errmsg_printf(error::WARN,

                        _("EventObserverList::addEventObserver() Duplicate event position %d for event '%s' from EventObserver plugin '%s'"),

                        position,

                        EventObserver::eventName(event), 

                        eventObserver->getName().c_str());

        }

      }

      observers->insert(std::pair<uint32_t, EventObserver *>(event_pos, eventObserver) );

    }

    /* Get the observer list for an event type. Will return NULL if no observer exists.*/

    ObserverMap *getObservers(enum EventObserver::EventType event)

    {

      return event_observer_lists[event];

    }

  };

  //---------

  /* registerEvent() is called from the event observer plugins to add themselves to

   * the event observer list to be notified when the specified event takes place.

   */ 

  void EventObserver::registerEvent(EventObserverList &observers, EventType event, int32_t position)

  {

    observers.addObserver(this, event, position);

  }

  /*========================================================*/

  /*              Table Event Observer handling:           */

  /*========================================================*/

  //----------

  /* For each EventObserver plugin call its registerTableEventsDo() meathod so that it can

   * register what events, if any, it is interested in on this table.

   */ 

  class RegisterTableEventsIterate : public std::unary_function<EventObserver *, void>

  {

    TableShare &table_share;

    EventObserverList &observers;

  public:

    RegisterTableEventsIterate(TableShare &table_share_arg, EventObserverList &observers_arg): 

      table_share(table_share_arg), observers(observers_arg) {}

    inline result_type operator() (argument_type eventObserver)

    {

      eventObserver->registerTableEventsDo(table_share, observers);

    }

  };

  //----------

  /* 

   * registerTableEvents() is called by drizzle to register all plugins that

   * may be interested in table events on the newly created TableShare object.

   */ 

  void EventObserver::registerTableEvents(TableShare &table_share)

  {

    if (all_event_plugins.empty())

      return;

    EventObserverList *observers;

    observers= table_share.getTableObservers();

    if (observers != NULL) 

		{

			errmsg_printf(error::WARN,

									_("EventObserver::registerTableEvents(): Table already has events registered on it: probable programming error."));

			table_share.setTableObservers(NULL);

      delete observers;

    }

		observers= new EventObserverList();

		table_share.setTableObservers(observers);

    std::for_each(all_event_plugins.begin(), all_event_plugins.end(),

                  RegisterTableEventsIterate(table_share, *observers));

  }

  //----------

  /* Cleanup before freeing the TableShare object. */

  void EventObserver::deregisterTableEvents(TableShare &table_share)

  {

   if (all_event_plugins.empty())

      return;

    EventObserverList *observers= table_share.getTableObservers();

    if (observers) 

    {

      table_share.setTableObservers(NULL);

      delete observers;

    }

  }

  /*========================================================*/

  /*              Schema Event Observer handling:           */

  /*========================================================*/

  //----------

  /* For each EventObserver plugin call its registerSchemaEventsDo() meathod so that it can

   * register what events, if any, it is interested in on the schema.

   */ 

  class RegisterSchemaEventsIterate : public std::unary_function<EventObserver *, void>

  {

    const std::string &db;

    EventObserverList &observers;

  public:

    RegisterSchemaEventsIterate(const std::string &db_arg, EventObserverList &observers_arg) :     

      db(db_arg),

      observers(observers_arg){}

    inline result_type operator() (argument_type eventObserver)

    {

      eventObserver->registerSchemaEventsDo(db, observers);

    }

  };

  //----------

  /* 

   * registerSchemaEvents() is called by drizzle to register all plugins that

   * may be interested in schema events on the database.

   */ 

  void EventObserver::registerSchemaEvents(Session &session, const std::string &db)

  {

    if (all_event_plugins.empty())

      return;

    EventObserverList *observers= session.getSchemaObservers(db);

    if (observers == NULL) 

      observers= session.setSchemaObservers(db, new EventObserverList());

    std::for_each(all_event_plugins.begin(), all_event_plugins.end(),

                  RegisterSchemaEventsIterate(db, *observers));

  }

  //----------

  /* Cleanup before freeing the Session object. */

  void EventObserver::deregisterSchemaEvents(EventObserverList *observers)

  {

      delete observers;

   }

  /*========================================================*/

  /*             Session Event Observer handling:           */

  /*========================================================*/

  //----------

  /* For each EventObserver plugin call its registerSessionEventsDo() meathod so that it can

   * register what events, if any, it is interested in on this session.

   */ 

  class RegisterSessionEventsIterate : public std::unary_function<EventObserver *, void>

  {

    Session &session;

    EventObserverList &observers;

  public:

    RegisterSessionEventsIterate(Session &session_arg, EventObserverList &observers_arg) : 

      session(session_arg), observers(observers_arg) {}

    inline result_type operator() (argument_type eventObserver)

    {

      eventObserver->registerSessionEventsDo(session, observers);

    }

  };

  //----------

  /* 

   * registerSessionEvents() is called by drizzle to register all plugins that

   * may be interested in session events on the newly created session.

   */ 

  void EventObserver::registerSessionEvents(Session &session)

  {

    if (all_event_plugins.empty())

      return;

    EventObserverList *observers;

    observers= session.getSessionObservers();

		if (observers) { // This should not happed

			errmsg_printf(error::WARN,

									_("EventObserver::registerSessionEvents(): Session already has events registered on it: probable programming error."));

			session.setSessionObservers(NULL);

			delete observers;

		}

	observers= new EventObserverList();

	session.setSessionObservers(observers);

  std::for_each(all_event_plugins.begin(), all_event_plugins.end(),

                RegisterSessionEventsIterate(session, *observers));

  }

  //----------

  /* Cleanup before freeing the session object. */

  void EventObserver::deregisterSessionEvents(EventObserverList *observers)

  {

      delete observers;

  }

  /* Event observer list iterator: */

  //----------

  class EventIterate : public std::unary_function<std::pair<uint32_t, EventObserver *>, bool>

  {

    EventData &data;

  public:

    EventIterate(EventData &data_arg) :

      std::unary_function<std::pair<uint32_t, EventObserver *>, bool>(),

      data(data_arg)

    {}

    inline result_type operator()(argument_type handler)

    {

      bool result= handler.second->observeEventDo(data);

      if (result)

      {

        /* TRANSLATORS: The leading word "EventObserver" is the name

          of the plugin api, and so should not be translated. */

        errmsg_printf(error::ERROR,

                      _("EventIterate event handler '%s' failed for event '%s'"),

                      handler.second->getName().c_str(), handler.second->eventName(data.event));

      }

      return result;

    }

  };

  /*==========================================================*/

  /* Generic meathods called by drizzle to notify all interested  

   * plugins of an event,

 */

  // Call all event observers interested in the event.

  bool EventData::callEventObservers()

  {

    EventObserverList::ObserverMap *eventObservers;

    if (observerList == NULL)

      return false; // Nobody was interested in the event. :(

    eventObservers = observerList->getObservers(event);

    if (eventObservers == NULL)

      return false; // Nobody was interested in the event. :(

    /* Use find_if instead of foreach so that we can collect return codes */

    EventObserverList::ObserverMap::iterator iter=

      std::find_if(eventObservers->begin(), eventObservers->end(),

                   EventIterate(*this)); 

    /* If iter is == end() here, that means that all of the plugins returned

     * false, which in this case means they all succeeded. Since we want to 

     * return false on success, we return the value of the two being !=.

   */

    return iter != eventObservers->end();

  }

  //--------

  bool SessionEventData::callEventObservers()

  {

    observerList= session.getSessionObservers();

    return EventData::callEventObservers();

  }

  bool SessionEventData::hasEvents(Session &in_session)

  {

    return (in_session.getSessionObservers() != NULL);

  }

  //--------

  bool SchemaEventData::callEventObservers()

  {

    observerList= session.getSchemaObservers(db);

    if (!observerList) 

    {

      EventObserver::registerSchemaEvents(session, db);

      observerList= session.getSchemaObservers(db);

    }

    return EventData::callEventObservers();

  }

  //--------

  bool TableEventData::callEventObservers()

  {

    observerList= table.getMutableShare()->getTableObservers();

    return EventData::callEventObservers();

  }

  bool TableEventData::hasEvents(Table &in_table)

  {

    return (in_table.getMutableShare()->getTableObservers() != NULL);

  }

  /*==========================================================*/

  /* Static meathods called by drizzle to notify interested plugins 

   * of a schema event.

 */

  bool EventObserver::beforeDropTable(Session &session, const drizzled::identifier::Table &table)

  {

    if (all_event_plugins.empty())

      return false;

    BeforeDropTableEventData eventData(session, table);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterDropTable(Session &session, const drizzled::identifier::Table &table, int err)

  {

    if (all_event_plugins.empty())

      return false;

    AfterDropTableEventData eventData(session, table, err);

    return eventData.callEventObservers();

  }

  bool EventObserver::beforeRenameTable(Session &session, const drizzled::identifier::Table &from, const drizzled::identifier::Table &to)

  {

    if (all_event_plugins.empty())

      return false;

    BeforeRenameTableEventData eventData(session, from, to);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterRenameTable(Session &session, const drizzled::identifier::Table &from, const drizzled::identifier::Table &to, int err)

  {

    if (all_event_plugins.empty())

      return false;

    AfterRenameTableEventData eventData(session, from, to, err);

    return eventData.callEventObservers();

  }

  /*==========================================================*/

  /* Static meathods called by drizzle to notify interested plugins 

   * of a table event.

   *

   * A quick test is done first to see if there are any interested observers.

 */

  bool EventObserver::beforeInsertRecord(Table &table, unsigned char *buf)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    BeforeInsertRecordEventData eventData(*(table.in_use), table, buf);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterInsertRecord(Table &table, const unsigned char *buf, int err)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    AfterInsertRecordEventData eventData(*(table.in_use), table, buf, err);

    return eventData.callEventObservers();

  }

  bool EventObserver::beforeDeleteRecord(Table &table, const unsigned char *buf)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    BeforeDeleteRecordEventData eventData(*(table.in_use), table, buf);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterDeleteRecord(Table &table, const unsigned char *buf, int err)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    AfterDeleteRecordEventData eventData(*(table.in_use), table, buf, err);

    return eventData.callEventObservers();

  }

  bool EventObserver::beforeUpdateRecord(Table &table, const unsigned char *old_data, unsigned char *new_data)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    BeforeUpdateRecordEventData eventData(*(table.in_use), table, old_data, new_data);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterUpdateRecord(Table &table, const unsigned char *old_data, unsigned char *new_data, int err)

  {

    if (all_event_plugins.empty() || !TableEventData::hasEvents(table))

      return false;

    AfterUpdateRecordEventData eventData(*(table.in_use), table, old_data, new_data, err);

    return eventData.callEventObservers();

  }

  /*==========================================================*/

  /* Static meathods called by drizzle to notify interested plugins 

   * of a session event.

   *

   * A quick test is done first to see if there are any interested observers.

*/

  bool EventObserver::beforeCreateDatabase(Session &session, const std::string &db)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    BeforeCreateDatabaseEventData eventData(session, db);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterCreateDatabase(Session &session, const std::string &db, int err)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    AfterCreateDatabaseEventData eventData(session, db, err);

    return eventData.callEventObservers();

  }

  bool EventObserver::beforeDropDatabase(Session &session, const std::string &db)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    BeforeDropDatabaseEventData eventData(session, db);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterDropDatabase(Session &session, const std::string &db, int err)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    AfterDropDatabaseEventData eventData(session, db, err);

    return eventData.callEventObservers();

  }

  bool EventObserver::connectSession(Session &session)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    ConnectSessionEventData eventData(session);

    return eventData.callEventObservers();

  }

  bool EventObserver::disconnectSession(Session &session)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    DisconnectSessionEventData eventData(session);

    return eventData.callEventObservers();

  }

  bool EventObserver::beforeStatement(Session &session)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    BeforeStatementEventData eventData(session);

    return eventData.callEventObservers();

  }

  bool EventObserver::afterStatement(Session &session)

  {

    if (all_event_plugins.empty() || !SessionEventData::hasEvents(session))

      return false;

    AfterStatementEventData eventData(session);

    return eventData.callEventObservers();

  }

} /* namespace plugin */

} /* namespace drizzled */