release/src/router/mysql/server-tools/instance-manager/guardian.h

   1 #ifndef INCLUDES_MYSQL_INSTANCE_MANAGER_GUARDIAN_H
   2 #define INCLUDES_MYSQL_INSTANCE_MANAGER_GUARDIAN_H
   3 /* Copyright (c) 2004-2006 MySQL AB
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; version 2 of the License.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  17
  18
  19 #include <my_global.h>
  20 #include <my_sys.h>
  21 #include <my_list.h>
  22
  23 #include "thread_registry.h"
  24
  25 #if defined(__GNUC__) && defined(USE_PRAGMA_INTERFACE)
  26 #pragma interface
  27 #endif
  28
  29 class Instance;
  30 class Instance_map;
  31 class Thread_registry;
  32
  33 /**
  34   The guardian thread is responsible for monitoring and restarting of guarded
  35   instances.
  36 */
  37
  38 class Guardian: public Thread
  39 {
  40 public:
  41   Guardian(Thread_registry *thread_registry_arg,
  42            Instance_map *instance_map_arg);
  43   ~Guardian();
  44
  45   void init();
  46
  47 public:
  48   void request_shutdown();
  49
  50   bool is_stopped();
  51
  52   void lock();
  53   void unlock();
  54
  55   void ping();
  56
  57 protected:
  58   virtual void run();
  59
  60 private:
  61   void stop_instances();
  62
  63   void process_instance(Instance *instance);
  64
  65 private:
  66   /*
  67     LOCK_guardian protectes the members in this section:
  68       - shutdown_requested;
  69       - stopped;
  70
  71     Also, it is used for COND_guardian.
  72   */
  73   pthread_mutex_t LOCK_guardian;
  74
  75   /*
  76     Guardian's main loop waits on this condition. So, it should be signalled
  77     each time, when instance state has been changed and we want Guardian to
  78     wake up.
  79
  80     TODO: Change this to having data-scoped conditions, i.e. conditions,
  81     which indicate that some data has been changed.
  82   */
  83   pthread_cond_t COND_guardian;
  84
  85   /*
  86     This variable is set to TRUE, when Manager thread is shutting down.
  87     The flag is used by Guardian thread to understand that it's time to
  88     finish.
  89   */
  90   bool shutdown_requested;
  91
  92   /*
  93     This flag is set to TRUE on shutdown by Guardian thread, when all guarded
  94     mysqlds are stopped.
  95
  96     The flag is used in the Manager thread to wait for Guardian to stop all
  97     mysqlds.
  98   */
  99   bool stopped;
 100
 101   Thread_info thread_info;
 102   Thread_registry *thread_registry;
 103   Instance_map *instance_map;
 104
 105 private:
 106   Guardian(const Guardian &);
 107   Guardian&operator =(const Guardian &);
 108 };
 109
 110 #endif /* INCLUDES_MYSQL_INSTANCE_MANAGER_GUARDIAN_H */