1 files changed, 180 insertions, 0 deletions
diff --git a/server-tools/instance-manager/guardian.cc b/server-tools/instance-manager/guardian.cc
new file mode 100644
index 00000000000..ebc59d67906
--- /dev/null
+++ b/server-tools/instance-manager/guardian.cc
@@ -0,0 +1,180 @@
+/* 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;
+}
+