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/* Copyright (C) 2004 MySQL AB
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 */
#ifdef __GNUC__
#pragma implementation
#endif
#include "guardian.h"
#include "instance_map.h"
#include <string.h>
C_MODE_START
pthread_handler_decl(guardian, arg)
{
Guardian_thread *guardian_thread= (Guardian_thread *) arg;
guardian_thread->run();
return 0;
}
C_MODE_END
Guardian_thread::Guardian_thread(Thread_registry &thread_registry_arg,
Instance_map *instance_map_arg,
uint monitoring_interval_arg) :
Guardian_thread_args(thread_registry_arg, instance_map_arg,
monitoring_interval_arg),
thread_info(pthread_self())
{
pthread_mutex_init(&LOCK_guardian, 0);
thread_registry.register_thread(&thread_info);
init_alloc_root(&alloc, MEM_ROOT_BLOCK_SIZE, 0);
guarded_instances= NULL;
}
Guardian_thread::~Guardian_thread()
{
/* delay guardian destruction to the moment when no one needs it */
pthread_mutex_lock(&LOCK_guardian);
free_root(&alloc, MYF(0));
thread_registry.unregister_thread(&thread_info);
pthread_mutex_unlock(&LOCK_guardian);
pthread_mutex_destroy(&LOCK_guardian);
}
/*
Run guardian thread
SYNOPSYS
run()
DESCRIPTION
Check for all guarded instances and restart them if needed. If everything
is fine go and sleep for some time.
RETURN
The function return no value
*/
void Guardian_thread::run()
{
Instance *instance;
LIST *loop;
int i=0;
my_thread_init();
while (!thread_registry.is_shutdown())
{
pthread_mutex_lock(&LOCK_guardian);
loop= guarded_instances;
while (loop != NULL)
{
instance= (Instance *) loop->data;
if (instance != NULL)
{
if (!instance->is_running())
instance->start();
}
loop= loop->next;
}
pthread_mutex_unlock(&LOCK_guardian);
sleep(monitoring_interval);
}
my_thread_end();
}
/*
Start instance guarding
SYNOPSYS
guard()
instance_name the name of the instance to be guarded
name_len the length of the name
DESCRIPTION
The instance is added to the list of guarded instances.
RETURN
0 - ok
1 - error occured
*/
int Guardian_thread::guard(const char *instance_name, uint name_len)
{
LIST *lst;
Instance *instance;
lst= (LIST *) alloc_root(&alloc, sizeof(LIST));
if (lst == NULL) return 1;
instance= instance_map->find(instance_name, name_len);
/* we store the pointers to instances from the instance_map's MEM_ROOT */
lst->data= (void *) instance;
pthread_mutex_lock(&LOCK_guardian);
guarded_instances= list_add(guarded_instances, lst);
pthread_mutex_unlock(&LOCK_guardian);
return 0;
}
/*
TODO: perhaps it would make sense to create a pool of the LIST elements
elements and give them upon request. Now we are loosing a bit of memory when
guarded instance was stopped and then restarted (since we cannot free just
a piece of the MEM_ROOT).
*/
int Guardian_thread::stop_guard(const char *instance_name, uint name_len)
{
LIST *lst;
Instance *instance;
instance= instance_map->find(instance_name, name_len);
lst= guarded_instances;
if (lst == NULL) return 1;
pthread_mutex_lock(&LOCK_guardian);
while (lst != NULL)
{
/*
We compare only pointers, as we always use pointers from the
instance_map's MEM_ROOT.
*/
if ((Instance *) lst->data == instance)
{
guarded_instances= list_delete(guarded_instances, lst);
pthread_mutex_unlock(&LOCK_guardian);
return 0;
}
else lst= lst->next;
}
pthread_mutex_unlock(&LOCK_guardian);
/* if there is nothing to delete it is also fine */
return 0;
}
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