hello_events.cc

/*
 *  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 <cstdio>
#include <boost/program_options.hpp>
#include <drizzled/item.h>
#include <drizzled/module/option_map.h>
#include <drizzled/session.h>
#include <drizzled/table/instance/base.h>
#include "hello_events.h"
#include <drizzled/plugin.h>

namespace po= boost::program_options;
using namespace drizzled;
using namespace plugin;
using namespace std;

#define PLUGIN_NAME "hello_events1"

static bool sysvar_hello_events_enabled;
static HelloEvents *hello_events= NULL;
static string sysvar_db_list;
static string sysvar_table_list;

/*
 * Event observer positions are used to set the order in which
 * event observers are called in the case that more than one
 * plugin is interested in the same event. You should only specify
 * the order if it really matters because if more than one plugin 
 * request the same calling position only the first one gets it and
 * the others will not be registered for the event. For this reason
 * your plugin should always provide a way to reposition the event
 * observer to resolve such conflicts.
 *
 * If position matters you will always initialy ask for the first position (1)
 * or the last position (-1) in the calling order, for example it makes no sence 
 * to initially ask to be called in position 13.
 */
typedef constrained_check<uint64_t, INT32_MAX-1, 1> position_constraint;
typedef constrained_check<int32_t, -1, INT32_MIN+1> post_drop_constraint;

static position_constraint sysvar_before_write_position;      // Call this event observer first.
static position_constraint sysvar_before_update_position;
static post_drop_constraint sysvar_post_drop_db_position;  // I want my event observer to be called last. No reason, I just do!


//==================================
// My table event observers: 
static bool observeBeforeInsertRecord(BeforeInsertRecordEventData &data)
{

  static int count= 0;
  count++;
  data.session.setVariable("BEFORE_INSERT_RECORD", boost::lexical_cast<std::string>(count));
  return false;
}

//---
static void observeAfterInsertRecord(AfterInsertRecordEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_INSERT_RECORD", boost::lexical_cast<std::string>(count));
}

//---
static bool observeBeforeDeleteRecord(BeforeDeleteRecordEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_DELETE_RECORD", boost::lexical_cast<std::string>(count));
  return false;
}

//---
static void observeAfterDeleteRecord(AfterDeleteRecordEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_DELETE_RECORD", boost::lexical_cast<std::string>(count));
}

//---
static bool observeBeforeUpdateRecord(BeforeUpdateRecordEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("BEFORE_UPDATE_RECORD", boost::lexical_cast<std::string>(count));
  return false;
}

//---
static void observeAfterUpdateRecord(AfterUpdateRecordEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_UPDATE_RECORD", boost::lexical_cast<std::string>(count));
}

//==================================
// My schema event observers: 
static void observeAfterDropTable(AfterDropTableEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_DROP_TABLE", boost::lexical_cast<std::string>(count));
}

//---
static void observeAfterRenameTable(AfterRenameTableEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_RENAME_TABLE", boost::lexical_cast<std::string>(count));
}

//---
static void observeAfterCreateDatabase(AfterCreateDatabaseEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_CREATE_DATABASE", boost::lexical_cast<std::string>(count));
}

//---
static void observeAfterDropDatabase(AfterDropDatabaseEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_DROP_DATABASE", boost::lexical_cast<std::string>(count));
}

//---
static void observeConnectSession(ConnectSessionEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("CONNECT_SESSION", boost::lexical_cast<std::string>(count));
}

//---
static void observeDisconnectSession(DisconnectSessionEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("DISCONNECT_SESSION", boost::lexical_cast<std::string>(count));
}

//---
static void observeBeforeStatement(BeforeStatementEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("BEFORE_STATEMENT", boost::lexical_cast<std::string>(count));
}

//---
static void observeAfterStatement(AfterStatementEventData &data)
{
  static int count= 0;
  count++;
  data.session.setVariable("AFTER_STATEMENT", boost::lexical_cast<std::string>(count));
}

HelloEvents::~HelloEvents()
{ }

//==================================
/* This is where I register which table events my pluggin is interested in.*/
void HelloEvents::registerTableEventsDo(TableShare &table_share, EventObserverList &observers)
{
  if ((is_enabled == false) 
    || !isTableInteresting(table_share.getTableName())
    || !isDatabaseInteresting(table_share.getSchemaName()))
    return;
    
  registerEvent(observers, BEFORE_INSERT_RECORD, sysvar_before_write_position.get());
  // I want to be called first if passible
  registerEvent(observers, AFTER_INSERT_RECORD);
  registerEvent(observers, BEFORE_UPDATE_RECORD, sysvar_before_update_position.get());
  registerEvent(observers, AFTER_UPDATE_RECORD);
  registerEvent(observers, BEFORE_DELETE_RECORD);
  registerEvent(observers, AFTER_DELETE_RECORD);
}

//==================================
/* This is where I register which schema events my pluggin is interested in.*/
void HelloEvents::registerSchemaEventsDo(const std::string &db, EventObserverList &observers)
{
  if ((is_enabled == false) 
    || !isDatabaseInteresting(db))
    return;
    
  registerEvent(observers, AFTER_DROP_TABLE);
  registerEvent(observers, AFTER_RENAME_TABLE);
}

//==================================
/* This is where I register which session events my pluggin is interested in.*/
void HelloEvents::registerSessionEventsDo(Session &session, EventObserverList &observers)
{
  if ((is_enabled == false) 
    || !isSessionInteresting(session))
    return;
    
  registerEvent(observers, AFTER_CREATE_DATABASE);
  registerEvent(observers, AFTER_DROP_DATABASE, sysvar_post_drop_db_position.get());
  registerEvent(observers, DISCONNECT_SESSION);
  registerEvent(observers, CONNECT_SESSION);
  registerEvent(observers, BEFORE_STATEMENT);
  registerEvent(observers, AFTER_STATEMENT);
}


//==================================
/* The event observer.*/
bool HelloEvents::observeEventDo(EventData &data)
{
  switch (data.event) {
  case AFTER_DROP_TABLE:
    observeAfterDropTable((AfterDropTableEventData &)data);
    break;
    
  case AFTER_RENAME_TABLE:
    observeAfterRenameTable((AfterRenameTableEventData &)data);
    break;
    
  case BEFORE_INSERT_RECORD:
    observeBeforeInsertRecord((BeforeInsertRecordEventData &)data);
    break;
    
  case AFTER_INSERT_RECORD:
    observeAfterInsertRecord((AfterInsertRecordEventData &)data);
    break;     
       
  case BEFORE_UPDATE_RECORD:
    observeBeforeUpdateRecord((BeforeUpdateRecordEventData &)data);
    break;
             
  case AFTER_UPDATE_RECORD:
     observeAfterUpdateRecord((AfterUpdateRecordEventData &)data);
    break;     
    
  case BEFORE_DELETE_RECORD:
    observeBeforeDeleteRecord((BeforeDeleteRecordEventData &)data);
    break;

  case AFTER_DELETE_RECORD:
    observeAfterDeleteRecord((AfterDeleteRecordEventData &)data);
    break;

  case AFTER_CREATE_DATABASE:
    observeAfterCreateDatabase((AfterCreateDatabaseEventData &)data);
    break;

  case AFTER_DROP_DATABASE:
    observeAfterDropDatabase((AfterDropDatabaseEventData &)data);
    break;

  case CONNECT_SESSION:
    observeConnectSession((ConnectSessionEventData &)data);
    break;

  case DISCONNECT_SESSION:
    observeDisconnectSession((DisconnectSessionEventData &)data);
    break;

  case BEFORE_STATEMENT:
    observeBeforeStatement((BeforeStatementEventData &)data);
    break;

  case AFTER_STATEMENT:
    observeAfterStatement((AfterStatementEventData &)data);
    break;

  default:
    fprintf(stderr, "HelloEvents: Unexpected event '%s'\n", EventObserver::eventName(data.event));
 
  }
  
  return false;
}

//==================================
// Some custom things for my plugin:


/* Plugin initialization and system variables */

static void enable(Session*, sql_var_t)
{
  if (hello_events)
  {
    if (sysvar_hello_events_enabled)
    {
      hello_events->enable();
    }
    else
    {
      hello_events->disable();
    }
  }
}


static int set_db_list(Session *, set_var *var)
{
  const char *db_list= var->value->str_value.ptr();
  if (db_list == NULL)
    return 1;

  if (hello_events)
  {
    hello_events->setDatabasesOfInterest(db_list);
    sysvar_db_list= db_list;
  }
  return 0;
}

static int set_table_list(Session *, set_var *var)
{
  const char *table_list= var->value->str_value.ptr();
  if (table_list == NULL)
    return 1;

  if (hello_events)
  {
    hello_events->setTablesOfInterest(table_list);
    sysvar_table_list= table_list;
  }
  return 0;
}


static int init(module::Context &context)
{
  hello_events= new HelloEvents(PLUGIN_NAME);

  context.add(hello_events);

  if (sysvar_hello_events_enabled)
  {
    hello_events->enable();
  }

  context.registerVariable(new sys_var_bool_ptr("enable",
                                                &sysvar_hello_events_enabled,
                                                enable));
  context.registerVariable(new sys_var_std_string("watch_databases",
                                                  sysvar_db_list,
                                                  set_db_list));
  context.registerVariable(new sys_var_std_string("watch_tables",
                                                  sysvar_table_list,
                                                  set_table_list));
  context.registerVariable(new sys_var_constrained_value<uint64_t>("before_write_position",
                                                         sysvar_before_write_position));
  context.registerVariable(new sys_var_constrained_value<uint64_t>("before_update_position",
                                                         sysvar_before_update_position));
  context.registerVariable(new sys_var_constrained_value<int32_t>("post_drop_position",
                                                         sysvar_post_drop_db_position));


  return 0;
}

static void init_options(drizzled::module::option_context &context)
{
  context("enable",
          po::value<bool>(&sysvar_hello_events_enabled)->default_value(false)->zero_tokens(),
          N_("Enable Example Events Plugin"));
  context("watch-databases",
          po::value<string>(&sysvar_db_list)->default_value(""),
          N_("A comma delimited list of databases to watch"));
  context("watch-tables",
          po::value<string>(&sysvar_table_list)->default_value(""),
          N_("A comma delimited list of databases to watch"));
  context("before-write-position",
          po::value<position_constraint>(&sysvar_before_write_position)->default_value(1),
          N_("Before write row event observer call position"));
  context("before-update-position",
          po::value<position_constraint>(&sysvar_before_update_position)->default_value(1),
          N_("Before update row event observer call position"));
  context("post-drop-db-position",
          po::value<post_drop_constraint>(&sysvar_post_drop_db_position)->default_value(-1),
          N_("After drop database event observer call position"));
}



DRIZZLE_DECLARE_PLUGIN
{
  DRIZZLE_VERSION_ID,
  PLUGIN_NAME,
  "0.1",
  "Barry Leslie",
  N_("An example events Plugin"),
  PLUGIN_LICENSE_BSD,
  init,   /* Plugin Init      */
  NULL, /* depends */
  init_options    /* config options   */
}
DRIZZLE_DECLARE_PLUGIN_END;