more fixes for IM to substitude mysqld_safe in startup scripts

BitKeeper/deleted/.del-thread_repository.cc~bba09f64f8cb4037:
  Delete: server-tools/instance-manager/thread_repository.cc
BitKeeper/deleted/.del-thread_repository.h~e6a3b9cab7a6612a:
  Delete: server-tools/instance-manager/thread_repository.h
server-tools/instance-manager/commands.cc:
  All instances are guarded by default now, so we need to perform check on whether the instance is nonguarded,
  rather then guarded when adding it to the list of guarded instnces.
server-tools/instance-manager/guardian.cc:
  Guardian rewritten to start instances by default, and shut them down, when exiting. Behaviour of the guardian
  in case of the instance crash has changed. Now it tries to restart an instance constantly in the first 2 
  seconds after the crash was noticed, and then it tries restart an instance once in the MONITORING_INTERVAL.
  If it failed to restart instance for "restart_retry" (compiled-in value) times, guardian stops trying to
  restart it.
server-tools/instance-manager/guardian.h:
  Several new functions and variables declared.
server-tools/instance-manager/instance.cc:
  now start doesn't call stop(), but rather tries to remove the pidfile itself
server-tools/instance-manager/instance.h:
  cleanup
server-tools/instance-manager/instance_map.cc:
  no more "admin" options
server-tools/instance-manager/instance_map.h:
  User and password purged from instance_map options, as IM shouldn't know them
server-tools/instance-manager/instance_options.cc:
  new option added -- shutdown_delay, guarded option now called nonguaded and has the opposite meaning
server-tools/instance-manager/instance_options.h:
  appropriate changes, reflecting options addition/removal
server-tools/instance-manager/manager.cc:
  shutdown process is complicated a bit -- at first signal thread should stop guardian, and only then the IM
  itself
server-tools/instance-manager/messages.cc:
  update error message
server-tools/instance-manager/options.cc:
  admin user/password purged from mysqlmanager options

server-tools/instance-manager/commands.cc

@@ -274,10 +274,10 @@ int Show_instance_options::do_command(struct st_net *net,
         goto err;
     }
 
-    if (instance->options.is_guarded != NULL)
+    if (instance->options.nonguarded == NULL)
     {
       position= 0;
-      store_to_string(&send_buff, (char *) "guarded", &position);
+      store_to_string(&send_buff, (char *) "nonguarded", &position);
       store_to_string(&send_buff, "", &position);
       if (my_net_write(net, send_buff.buffer, (uint) position))
         goto err;
@@ -350,7 +350,7 @@ int Start_instance::execute(struct st_net *net, ulong connection_id)
     if (err_code= instance->start())
       return err_code;
 
-    if (instance->options.is_guarded != NULL)
+    if (instance->options.nonguarded == NULL)
         instance_map->guardian->guard(instance);
 
     net_send_ok(net, connection_id);
@@ -381,7 +381,7 @@ int Stop_instance::execute(struct st_net *net, ulong connection_id)
   }
   else
   {
-    if (instance->options.is_guarded != NULL)
+    if (instance->options.nonguarded == NULL)
         instance_map->guardian->
                stop_guard(instance);
     if ((err_code= instance->stop()))

server-tools/instance-manager/guardian.cc

@@ -46,6 +46,8 @@ Guardian_thread::Guardian_thread(Thread_registry &thread_registry_arg,
 {
   pthread_mutex_init(&LOCK_guardian, 0);
   pthread_cond_init(&COND_guardian, 0);
+  shutdown_guardian= FALSE;
+  is_stopped= FALSE;
   thread_registry.register_thread(&thread_info);
   init_alloc_root(&alloc, MEM_ROOT_BLOCK_SIZE, 0);
   guarded_instances= NULL;
@@ -65,6 +67,22 @@ Guardian_thread::~Guardian_thread()
 }
 
 
+void Guardian_thread::shutdown()
+{
+  pthread_mutex_lock(&LOCK_guardian);
+  shutdown_guardian= TRUE;
+  pthread_mutex_unlock(&LOCK_guardian);
+}
+
+
+void Guardian_thread::request_stop_instances()
+{
+  pthread_mutex_lock(&LOCK_guardian);
+  request_stop= TRUE;
+  pthread_mutex_unlock(&LOCK_guardian);
+}
+
+
 /*
   Run guardian thread
 
@@ -80,6 +98,7 @@ Guardian_thread::~Guardian_thread()
 void Guardian_thread::run()
 {
   Instance *instance;
+  int restart_retry= 100;
   LIST *loop;
   struct timespec timeout;
 
@@ -87,26 +106,68 @@ void Guardian_thread::run()
   pthread_mutex_lock(&LOCK_guardian);
 
 
-  while (!thread_registry.is_shutdown())
+  while (!shutdown_guardian)
   {
+    int status= 0;
     loop= guarded_instances;
     while (loop != NULL)
     {
-      instance= (Instance *) loop->data;
-      /* instance-> start already checks whether the instance is running */
-      if (instance->start() != ER_INSTANCE_ALREADY_STARTED)
-        log_info("guardian attempted to restart instance %s",
+      instance= ((GUARD_NODE *) loop->data)->instance;
+      if (!instance->is_running())
+      {
+        int state= 0;                           /* state of guardian */
+
+        if ((((GUARD_NODE *) loop->data)->crash_moment == 0))
+          state= 1;                             /* an instance just crashed */
+        else
+           if (time(NULL) - ((GUARD_NODE *) loop->data)->crash_moment <= 2)
+             /* try to restart an instance immediately */
+             state= 2;
+           else
+             state= 3;                          /* try to restart it */
+
+        if (state == 1)
+          ((GUARD_NODE *) loop->data)->crash_moment= time(NULL);
+
+        if ((state == 1) || (state == 2))
+        {
+          instance->start();
+          ((GUARD_NODE *) loop->data)->restart_counter++;
+          log_info("guardian: starting instance %s",
                    instance->options.instance_name);
+        }
+        else
+        {
+          if ((status == ETIMEDOUT) &&
+             (((GUARD_NODE *) loop->data)->restart_counter < restart_retry))
+          {
+           instance->start();
+           ((GUARD_NODE *) loop->data)->restart_counter++;
+           log_info("guardian: starting instance %s",
+                    instance->options.instance_name);
+          }
+        }
+      }
+      else /* clear status fields */
+      {
+        ((GUARD_NODE *) loop->data)->restart_counter= 0;
+        ((GUARD_NODE *) loop->data)->crash_moment= 0;
+      }
       loop= loop->next;
     }
     move_to_list(&starting_instances, &guarded_instances);
     timeout.tv_sec= time(NULL) + monitoring_interval;
     timeout.tv_nsec= 0;
 
-    pthread_cond_timedwait(&COND_guardian, &LOCK_guardian, &timeout);
+    status= pthread_cond_timedwait(&COND_guardian, &LOCK_guardian, &timeout);
   }
 
   pthread_mutex_unlock(&LOCK_guardian);
+  if (request_stop)
+    stop_instances();
+  is_stopped= TRUE;
+  /* now, when the Guardian is stopped we can stop the IM */
+  thread_registry.request_shutdown();
   my_thread_end();
 }
 
@@ -119,7 +180,7 @@ int Guardian_thread::start()
   instance_map->lock();
   while ((instance= iterator.next()))
   {
-    if ((instance->options.is_guarded != NULL) && (instance->is_running()))
+    if ((instance->options.nonguarded == NULL))
       if (guard(instance))
         return 1;
   }
@@ -170,12 +231,18 @@ void Guardian_thread::move_to_list(LIST **from, LIST **to)
 int Guardian_thread::add_instance_to_list(Instance *instance, LIST **list)
 {
   LIST *node;
+  GUARD_NODE *content;
 
   node= (LIST *) alloc_root(&alloc, sizeof(LIST));
-  if (node == NULL)
+  content= (GUARD_NODE *) alloc_root(&alloc, sizeof(GUARD_NODE));
+
+  if ((node == NULL) || (content == NULL))
     return 1;
   /* we store the pointers to instances from the instance_map's MEM_ROOT */
-  node->data= (void *) instance;
+  content->instance= instance;
+  content->restart_counter= 0;
+  content->crash_moment= 0;
+  node->data= (void *) content;
 
   pthread_mutex_lock(&LOCK_guardian);
   *list= list_add(*list, node);
@@ -205,7 +272,7 @@ int Guardian_thread::stop_guard(Instance *instance)
       We compare only pointers, as we always use pointers from the
       instance_map's MEM_ROOT.
     */
-    if ((Instance *) node->data == instance)
+    if (((GUARD_NODE *) node->data)->instance == instance)
     {
       guarded_instances= list_delete(guarded_instances, node);
       pthread_mutex_unlock(&LOCK_guardian);
@@ -219,3 +286,21 @@ int Guardian_thread::stop_guard(Instance *instance)
   return 0;
 }
 
+int Guardian_thread::stop_instances()
+{
+  Instance *instance;
+  Instance_map::Iterator iterator(instance_map);
+
+  while ((instance= iterator.next()))
+  {
+    if ((instance->options.nonguarded == NULL))
+    {
+      if (stop_guard(instance))
+        return 1;
+      /* let us try to stop the server */
+      instance->stop();
+    }
+  }
+
+  return 0;
+}

server-tools/instance-manager/guardian.h

@@ -24,6 +24,7 @@
 #pragma interface
 #endif
 
+class Instance;
 class Instance_map;
 
 #include "thread_registry.h"
@@ -35,6 +36,13 @@ pthread_handler_decl(guardian, arg);
 
 C_MODE_END
 
+typedef struct st_guard_node
+{
+  Instance *instance;
+  uint restart_counter;
+  time_t crash_moment;
+} GUARD_NODE;
+
 
 struct Guardian_thread_args
 {
@@ -67,13 +75,17 @@ class Guardian_thread: public Guardian_thread_args
   void run();
   int init();
   int start();
+  void shutdown();
+  void request_stop_instances();
   int guard(Instance *instance);
   int stop_guard(Instance *instance);
+  bool is_stopped;
 
 public:
   pthread_cond_t COND_guardian;
 
 private:
+  int stop_instances();
   int add_instance_to_list(Instance *instance, LIST **list);
   void move_to_list(LIST **from, LIST **to);
 
@@ -84,6 +96,13 @@ class Guardian_thread: public Guardian_thread_args
   LIST *starting_instances;
   MEM_ROOT alloc;
   enum { MEM_ROOT_BLOCK_SIZE= 512 };
+  /* this variable is set to TRUE when we want to stop Guardian thread */
+  bool shutdown_guardian;
+  /*
+    This var is usually set together with shutdown_guardian. this way we
+    request guardian to shut down all instances before termination
+  */
+  bool request_stop;
 };
 
 #endif /* INCLUDES_MYSQL_INSTANCE_MANAGER_GUARDIAN_H */

server-tools/instance-manager/instance.cc

@@ -42,10 +42,16 @@
 
 int Instance::start()
 {
-  /* echk for the pidfile and remove it */
+  pid_t pid;
+
   if (!is_running())
   {
-    stop();
+    if ((pid= options.get_pid()) != 0)          /* check the pidfile */
+      if (options.unlink_pidfile())             /* remove stalled pidfile */
+        log_error("cannot remove pidfile for instance %i, this might be \
+                  since IM lacks permmissions or hasn't found the pidifle",
+                  options.instance_name);
+
     log_info("starting instance %s", options.instance_name);
     switch (pid= fork()) {
     case 0:
@@ -145,14 +151,17 @@ int Instance::stop()
 {
   pid_t pid;
   struct timespec timeout;
-  time_t waitchild= 35;                         /*  */
+  int waitchild= DEFAULT_SHUTDOWN_DELAY;
+
+  if (options.shutdown_delay != NULL)
+    waitchild= atoi(options.shutdown_delay);
 
   if ((pid= options.get_pid()) != 0)            /* get pid from pidfile */
   {
     /*
       If we cannot kill mysqld, then it has propably crashed.
       Let us try to remove staled pidfile and return succes as mysqld
-      is stopped
+      is probably stopped
     */
     if (kill(pid, SIGTERM))
     {
@@ -161,9 +170,6 @@ int Instance::stop()
                   since IM lacks permmissions or hasn't found the pidifle",
                   options.instance_name);
 
-      log_error("The instance %s has probably crashed or IM lacks permissions \
-                to kill it. in either case something seems to be wrong. \
-                Check your setup", options.instance_name);
       return 0;
     }
 
@@ -174,7 +180,7 @@ int Instance::stop()
     if (pthread_mutex_lock(&instance_map->pid_cond.LOCK_pid))
       goto err; /* perhaps this should be procecced differently */
 
-    while (options.get_pid() != 0)
+    while (options.get_pid() != 0)              /* while server isn't stopped */
     {
       int status;
 

server-tools/instance-manager/instance.h

@@ -41,11 +41,9 @@ class Instance
   int cleanup();
 
 public:
+  enum { DEFAULT_SHUTDOWN_DELAY= 35 };
   Instance_options options;
 
-  /* connection to the instance */
-  pid_t pid;
-
 private:
   /*
     Mutex protecting the instance. Currently we use it to avoid the

server-tools/instance-manager/instance_map.cc

@@ -82,7 +82,8 @@ static int process_option(void * ctx, const char *group, const char *option)
 
   map = (Instance_map*) ctx;
   if (strncmp(group, prefix, sizeof prefix) == 0 &&
-      (my_isdigit(default_charset_info, group[sizeof prefix])))
+      ((my_isdigit(default_charset_info, group[sizeof prefix]))
+       || group[sizeof(prefix)] == '\0'))
     {
       if ((instance= map->find(group, strlen(group))) == NULL)
       {
@@ -109,13 +110,9 @@ static int process_option(void * ctx, const char *group, const char *option)
 C_MODE_END
 
 
-Instance_map::Instance_map(const char *default_mysqld_path_arg,
-                           const char *default_admin_user_arg,
-                           const char *default_admin_password_arg)
+Instance_map::Instance_map(const char *default_mysqld_path_arg)
 {
   mysqld_path= default_mysqld_path_arg;
-  user= default_admin_user_arg;
-  password= default_admin_password_arg;
 
   pthread_mutex_init(&LOCK_instance_map, 0);
 }
@@ -195,7 +192,7 @@ void Instance_map::complete_initialization()
   {
     instance= (Instance *) hash_element(&hash, i);
     instance->complete_initialization(this);
-    instance->options.complete_initialization(mysqld_path, user, password);
+    instance->options.complete_initialization(mysqld_path);
     i++;
   }
 }

server-tools/instance-manager/instance_map.h

@@ -71,9 +71,7 @@ class Instance_map
   int unlock();
   int init();
 
-  Instance_map(const char *default_mysqld_path_arg,
-               const char *default_admin_user_arg,
-               const char *default_admin_password_arg);
+  Instance_map(const char *default_mysqld_path_arg);
   ~Instance_map();
 
   /* loads options from config files */
@@ -85,9 +83,6 @@ class Instance_map
 
 public:
   const char *mysqld_path;
-  /* user an password to shutdown MySQL */
-  const char *user;
-  const char *password;
   Guardian_thread *guardian;
   /* structure used for syncronization reasons in the stop command */
   CHILD_COND pid_cond;

server-tools/instance-manager/instance_options.cc

@@ -113,9 +113,7 @@ pid_t Instance_options::get_pid()
 }
 
 
-int Instance_options::complete_initialization(const char *default_path,
-                                              const char *default_user,
-                                              const char *default_password)
+int Instance_options::complete_initialization(const char *default_path)
 {
   const char *tmp;
 
@@ -199,7 +197,8 @@ int Instance_options::add_option(const char* option)
     {"--bind-address=", 15, &mysqld_bind_address, SAVE_WHOLE_AND_ADD},
     {"--pid-file=", 11, &mysqld_pid_file, SAVE_WHOLE_AND_ADD},
     {"--mysqld-path=", 14, &mysqld_path, SAVE_VALUE},
-    {"--guarded", 9, &is_guarded, SAVE_WHOLE},
+    {"--nonguarded", 9, &nonguarded, SAVE_WHOLE},
+    {"--shutdown_delay", 9, &shutdown_delay, SAVE_VALUE},
     {NULL, 0, NULL, 0}
   };
   struct selected_options_st *selected_options;

server-tools/instance-manager/instance_options.h

@@ -38,14 +38,12 @@ class Instance_options
 public:
   Instance_options() :
     mysqld_socket(0), mysqld_datadir(0), mysqld_bind_address(0),
-    mysqld_pid_file(0), mysqld_port(0), mysqld_path(0), is_guarded(0),
+    mysqld_pid_file(0), mysqld_port(0), mysqld_path(0), nonguarded(0),
     filled_default_options(0)
   {}
   ~Instance_options();
   /* fills in argv */
-  int complete_initialization(const char *default_path,
-                              const char *default_user,
-                              const char *default_password);
+  int complete_initialization(const char *default_path);
 
   int add_option(const char* option);
   int init(const char *instance_name_arg);
@@ -71,7 +69,8 @@ class Instance_options
   uint instance_name_len;
   const char *instance_name;
   const char *mysqld_path;
-  const char *is_guarded;
+  const char *nonguarded;
+  const char *shutdown_delay;
   DYNAMIC_ARRAY options_array;
 private:
   int add_to_argv(const char *option);

server-tools/instance-manager/manager.cc

@@ -67,9 +67,7 @@ void manager(const Options &options)
   */
 
   User_map user_map;
-  Instance_map instance_map(options.default_mysqld_path,
-                            options.default_admin_user,
-                            options.default_admin_password);
+  Instance_map instance_map(options.default_mysqld_path);
   Guardian_thread guardian_thread(thread_registry,
                                   &instance_map,
                                   options.monitoring_interval);
@@ -181,8 +179,17 @@ void manager(const Options &options)
         pthread_cond_broadcast(&guardian_thread.COND_guardian);
       break;
       default:
+        if (!guardian_thread.is_stopped)
+        {
+          guardian_thread.request_stop_instances();
+          guardian_thread.shutdown();
+          pthread_cond_broadcast(&guardian_thread.COND_guardian);
+        }
+        else
+        {
           thread_registry.deliver_shutdown();
           shutdown_complete= TRUE;
+        }
       break;
     }
   }

server-tools/instance-manager/messages.cc

@@ -45,8 +45,8 @@ static const char *mysqld_error_message(unsigned sql_errno)
   case ER_BAD_INSTANCE_NAME:
     return "Bad instance name. Check that the instance with such a name exists";
   case ER_INSTANCE_IS_NOT_STARTED:
-    return "Cannot stop instance. Perhaps the instance is not started or you"
-           " have specified wrong username/password in the config file";
+    return "Cannot stop instance. Perhaps the instance is not started, or was started"
+            "manually, so IM cannot find the pidfile.";
   case ER_INSTANCE_ALREADY_STARTED:
     return "The instance is already started";
   case ER_CANNOT_START_INSTANCE:

server-tools/instance-manager/options.cc

@@ -35,8 +35,6 @@ const char *Options::pid_file_name= QUOTE(DEFAULT_PID_FILE_NAME);
 const char *Options::socket_file_name= QUOTE(DEFAULT_SOCKET_FILE_NAME);
 const char *Options::password_file_name= QUOTE(DEFAULT_PASSWORD_FILE_NAME);
 const char *Options::default_mysqld_path= QUOTE(DEFAULT_MYSQLD_PATH);
-const char *Options::default_admin_user= QUOTE(DEFAULT_USER);
-const char *Options::default_admin_password= QUOTE(DEFAULT_PASSWORD);
 const char *Options::bind_address= 0;              /* No default value */
 uint Options::monitoring_interval= DEFAULT_MONITORING_INTERVAL;
 uint Options::port_number= DEFAULT_PORT;
@@ -55,8 +53,6 @@ enum options {
   OPT_RUN_AS_SERVICE,
   OPT_USER,
   OPT_PASSWORD,
-  OPT_DEFAULT_ADMIN_USER,
-  OPT_DEFAULT_ADMIN_PASSWORD,
   OPT_MONITORING_INTERVAL,
   OPT_PORT,
   OPT_BIND_ADDRESS
@@ -98,18 +94,6 @@ static struct my_option my_long_options[] =
     (gptr *) &Options::default_mysqld_path, (gptr *) &Options::default_mysqld_path,
     0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0 },
 
-  { "default-admin-user", OPT_DEFAULT_ADMIN_USER, "Username to shutdown MySQL"
-                                           " instances.",
-                   (gptr *) &Options::default_admin_user,
-                   (gptr *) &Options::default_admin_user,
-                   0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0 },
-
-  { "default-admin-password", OPT_DEFAULT_ADMIN_PASSWORD, "Password to"
-                                            "shutdown MySQL instances.",
-                   (gptr *) &Options::default_admin_password,
-                   (gptr *) &Options::default_admin_password,
-                   0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0 },
-
   { "monitoring-interval", OPT_MONITORING_INTERVAL, "Interval to monitor instances"
                                             " in seconds.",
                    (gptr *) &Options::monitoring_interval,

server-tools/instance-manager/thread_repository.cc

-/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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 "thread_repository.h"
-#include <assert.h>
-#include <signal.h>
-#include "log.h"
-
-
-/* Kick-off signal handler */
-  
-enum { THREAD_KICK_OFF_SIGNAL= SIGUSR2 };
-
-static void handle_signal(int __attribute__((unused)) sig_no)
-{
-}
-
-
-/*
-  TODO: think about moving signal information (now it's shutdown_in_progress)
-  to Thread_info. It will reduce contention and allow signal deliverence to
-  a particular thread, not to the whole worker crew 
-*/
-
-Thread_repository::Thread_repository() :
-  shutdown_in_progress(false)
-{
-  pthread_mutex_init(&LOCK_thread_repository, 0);
-  pthread_cond_init(&COND_thread_repository_is_empty, 0);
-
-  /* head is used by-value to simplify nodes inserting */
-  head.next= head.prev= &head;
-}
-
-
-Thread_repository::~Thread_repository()
-{
-  /* Check that no one uses the repository. */
-  pthread_mutex_lock(&LOCK_thread_repository);
-
-  /* All threads must unregister */
-  DBUG_ASSERT(head.next == &head);
-
-  pthread_mutex_unlock(&LOCK_thread_repository);
-  pthread_cond_destroy(&COND_thread_repository_is_empty);
-  pthread_mutex_destroy(&LOCK_thread_repository);
-}
-
-
-/*
-  
-  Set signal handler for kick-off thread, and insert a thread info to the
-  repository. New node is appended to the end of the list; head.prev always
-  points to the last node.
-*/
-
-void Thread_repository::register_thread(Thread_info *info)
-{
-  struct sigaction sa;
-  sa.sa_handler= handle_signal;
-  sa.sa_flags= 0;
-  sigemptyset(&sa.sa_mask);
-  sigaction(THREAD_KICK_OFF_SIGNAL, &sa, 0);
-
-  info->current_cond= 0;
-
-  pthread_mutex_lock(&LOCK_thread_repository);
-  info->next= &head;
-  info->prev= head.prev;
-  head.prev->next= info;
-  head.prev= info;
-  pthread_mutex_unlock(&LOCK_thread_repository);
-}
-
-
-/*
-  Unregister a thread from the repository and free Thread_info structure.
-  Every registered thread must unregister. Unregistering should be the last 
-  thing a thread is doing, otherwise it could have no time to finalize.
-*/
-
-void Thread_repository::unregister_thread(Thread_info *info)
-{
-  pthread_mutex_lock(&LOCK_thread_repository);
-  info->prev->next= info->next;
-  info->next->prev= info->prev;
-  if (head.next == &head)
-    pthread_cond_signal(&COND_thread_repository_is_empty);
-  pthread_mutex_unlock(&LOCK_thread_repository);
-}
-
-
-/*
-  Check whether shutdown is in progress, and if yes, return immidiately.
-  Else set info->current_cond and call pthread_cond_wait. When
-  pthread_cond_wait returns, unregister current cond and check the shutdown
-  status again.
-  RETURN VALUE
-    return value from pthread_cond_wait
-*/
-
-int Thread_repository::cond_wait(Thread_info *info, pthread_cond_t *cond,
-                                  pthread_mutex_t *mutex, bool *is_shutdown)
-{
-  pthread_mutex_lock(&LOCK_thread_repository);
-  *is_shutdown= shutdown_in_progress;
-  if (*is_shutdown)
-  {
-    pthread_mutex_unlock(&LOCK_thread_repository);
-    return 0;
-  }
-  info->current_cond= cond;
-  pthread_mutex_unlock(&LOCK_thread_repository);
-  /* sic: race condition here, cond can be signaled in deliver_shutdown */
-  int rc= pthread_cond_wait(cond, mutex);
-  pthread_mutex_lock(&LOCK_thread_repository);
-  info->current_cond= 0;
-  *is_shutdown= shutdown_in_progress;
-  pthread_mutex_unlock(&LOCK_thread_repository);
-  return rc;
-}
-
-
-/*
-  Deliver shutdown message to the workers crew.
-  As it's impossible to avoid all race conditions, we signal latecomers
-  again.
-*/
-
-void Thread_repository::deliver_shutdown()
-{
-  struct timespec shutdown_time;
-  set_timespec(shutdown_time, 1);
-  Thread_info *info;
-
-  pthread_mutex_lock(&LOCK_thread_repository);
-  shutdown_in_progress= true;
-  for (info= head.next; info != &head; info= info->next)
-  {
-    pthread_kill(info->thread_id, THREAD_KICK_OFF_SIGNAL);
-    /*
-      sic: race condition here, the thread may not yet fall into
-      pthread_cond_wait.
-    */
-    if (info->current_cond)
-      pthread_cond_signal(info->current_cond);
-  }
-  while (pthread_cond_timedwait(&COND_thread_repository_is_empty,
-                                &LOCK_thread_repository,
-                                &shutdown_time) != ETIMEDOUT &&
-         head.next != &head)
-    ;
-  /*
-    If previous signals did not reach some threads, they must be sleeping 
-    in pthread_cond_wait or a blocking syscall. Wake them up: 
-    every thread shall check signal variables after each syscall/cond_wait,
-    so this time everybody should be informed (presumably each worker can
-    get CPU during shutdown_time.)
-  */
-  for (info= head.next; info != &head; info= info->next)
-  {
-    pthread_kill(info->thread_id, THREAD_KICK_OFF_SIGNAL);
-    if (info->current_cond)
-      pthread_cond_signal(info->current_cond);
-  }
-  pthread_mutex_unlock(&LOCK_thread_repository);
-}
-

server-tools/instance-manager/thread_repository.h

-#ifndef INCLUDES_MYSQL_INSTANCE_MANAGER_THREAD_REPOSITORY_HH
-#define INCLUDES_MYSQL_INSTANCE_MANAGER_THREAD_REPOSITORY_HH
-/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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 */
-
-/*
-  A multi-threaded application shall nicely work with signals.
-
-  This means it shall, first of all, shut down nicely on ``quit'' signals:
-  stop all running threads, cleanup and exit.
-
-  Note, that a thread can't be shut down nicely if it doesn't want to be.
-  That's why to perform clean shutdown, all threads consituting a process
-  must observe certain rules. Here we use the rules, described in Butenhof
-  book 'Programming with POSIX threads', namely:
-  - all user signals are handled in 'signal thread' in synchronous manner
-  (by means of sigwait). To guarantee that the signal thread is the only who
-  can receive user signals, all threads block them, and signal thread is 
-  the only who calls sigwait() with an apporpriate sigmask. 
-  To propogate a signal to the workers the signal thread sets
-  a variable, corresponding to the signal. Additionally the signal thread
-  sends each worker an internal signal (by means of pthread_kill) to kick it
-  out from possible blocking syscall, and possibly pthread_cond_signal if 
-  some thread is blocked in pthread_cond_[timed]wait.
-  - a worker handles only internal 'kick' signal (the handler does nothing).
-  In case when a syscall returns 'EINTR' the worker checks all
-  signal-related variables and behaves accordingly.
-  Also these variables shall be checked from time to time in long
-  CPU-bounded operations, and before/after pthread_cond_wait. (It's supposed
-  that a worker thread either waits in a syscall/conditional variable, or
-  computes something.)
-  - to guarantee signal deliverence, there should be some kind of feedback,
-  e. g. all workers shall account in the signal thread Thread Repository and
-  unregister from it on exit.
-  
-  Configuration reload (on SIGHUP) and thread timeouts/alarms can be handled
-  in manner, similar to ``quit'' signals.
-*/
-
-#ifdef __GNUC__
-#pragma interface
-#endif
-
-#include <my_global.h>
-#include <my_pthread.h>
-
-
-/*
-  Thread_info - repository entry for each worker thread
-  All entries comprise double-linked list like:
-     0 -- entry -- entry -- entry - 0
-  Double-linked list is used to unregister threads easy.
-*/
-
-class Thread_info
-{
-  pthread_cond_t *current_cond;
-  Thread_info *prev, *next;
-  pthread_t thread_id;
-  Thread_info() {}
-  friend class Thread_repository;
-public:
-  Thread_info(pthread_t thread_id_arg) : thread_id(thread_id_arg) {}
-};
-
-
-/*
-  Thread_repository - contains handles for each worker thread to deliver
-  signal information to workers.
-*/
-
-class Thread_repository
-{
-public:
-  Thread_repository();
-  ~Thread_repository();
-
-  void register_thread(Thread_info *info);
-  void unregister_thread(Thread_info *info);
-  void deliver_shutdown();
-  inline bool is_shutdown();
-  int cond_wait(Thread_info *info, pthread_cond_t *cond,
-                 pthread_mutex_t *mutex, bool *is_shutdown);
-private:
-  Thread_info head;
-  bool shutdown_in_progress;
-  pthread_mutex_t LOCK_thread_repository;
-  pthread_cond_t COND_thread_repository_is_empty;
-};
-
-
-inline bool Thread_repository::is_shutdown()
-{
-  pthread_mutex_lock(&LOCK_thread_repository);
-  bool res= shutdown_in_progress;
-  pthread_mutex_unlock(&LOCK_thread_repository);
-  return res;
-}
-
-#endif // INCLUDES_MYSQL_INSTANCE_MANAGER_THREAD_REPOSITORY_HH