EVOLUTION-MANAGER

Edit File: wqueue.c

/* Copyright (c) 2007, 2008, Sun Microsystems, Inc, Copyright (c) 2011, 2012, Monty Program 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; 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 Street, Fifth Floor, Boston, MA 02111-1301 USA */ #include <my_global.h> #include <wqueue.h> #define STRUCT_PTR(TYPE, MEMBER, a) \ (TYPE *) ((char *) (a) - offsetof(TYPE, MEMBER)) /* Link a thread into double-linked queue of waiting threads. SYNOPSIS wqueue_link_into_queue() wqueue pointer to the queue structure thread pointer to the thread to be added to the queue RETURN VALUE none NOTES. Queue is represented by a circular list of the thread structures The list is double-linked of the type (**prev,*next), accessed by a pointer to the last element. */ void wqueue_link_into_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) { struct st_my_thread_var *last; if (!(last= wqueue->last_thread)) { /* Queue is empty */ thread->next= thread; thread->prev= &thread->next; } else { thread->prev= last->next->prev; last->next->prev= &thread->next; thread->next= last->next; last->next= thread; } wqueue->last_thread= thread; } /* Add a thread to single-linked queue of waiting threads SYNOPSIS wqueue_add_to_queue() wqueue pointer to the queue structure thread pointer to the thread to be added to the queue RETURN VALUE none NOTES. Queue is represented by a circular list of the thread structures The list is single-linked of the type (*next), accessed by a pointer to the last element. */ void wqueue_add_to_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) { struct st_my_thread_var *last; if (!(last= wqueue->last_thread)) thread->next= thread; else { thread->next= last->next; last->next= thread; } #ifndef DBUG_OFF thread->prev= NULL; /* force segfault if used */ #endif wqueue->last_thread= thread; } /* Unlink a thread from double-linked queue of waiting threads SYNOPSIS wqueue_unlink_from_queue() wqueue pointer to the queue structure thread pointer to the thread to be removed from the queue RETURN VALUE none NOTES. See NOTES for link_into_queue */ void wqueue_unlink_from_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) { if (thread->next == thread) /* The queue contains only one member */ wqueue->last_thread= NULL; else { thread->next->prev= thread->prev; *thread->prev= thread->next; if (wqueue->last_thread == thread) wqueue->last_thread= STRUCT_PTR(struct st_my_thread_var, next, thread->prev); } thread->next= NULL; } /* Remove all threads from queue signaling them to proceed SYNOPSIS wqueue_realease_queue() wqueue pointer to the queue structure thread pointer to the thread to be added to the queue RETURN VALUE none NOTES. See notes for add_to_queue When removed from the queue each thread is signaled via condition variable thread->suspend. */ void wqueue_release_queue(WQUEUE *wqueue) { struct st_my_thread_var *last= wqueue->last_thread; struct st_my_thread_var *next= last->next; struct st_my_thread_var *thread; do { thread= next; mysql_cond_signal(&thread->suspend); next= thread->next; thread->next= NULL; } while (thread != last); wqueue->last_thread= NULL; } /** @brief Removes all threads waiting for read or first one waiting for write. @param wqueue pointer to the queue structure @param thread pointer to the thread to be added to the queue @note This function is applicable only to single linked lists. */ void wqueue_release_one_locktype_from_queue(WQUEUE *wqueue) { struct st_my_thread_var *last= wqueue->last_thread; struct st_my_thread_var *next= last->next; struct st_my_thread_var *thread; struct st_my_thread_var *new_list= NULL; uint first_type= next->lock_type; if (first_type == MY_PTHREAD_LOCK_WRITE) { /* release first waiting for write lock */ mysql_cond_signal(&next->suspend); if (next == last) wqueue->last_thread= NULL; else last->next= next->next; next->next= NULL; return; } do { thread= next; next= thread->next; if (thread->lock_type == MY_PTHREAD_LOCK_WRITE) { /* skip waiting for write lock */ if (new_list) { thread->next= new_list->next; new_list= new_list->next= thread; } else new_list= thread->next= thread; } else { /* release waiting for read lock */ mysql_cond_signal(&thread->suspend); thread->next= NULL; } } while (thread != last); wqueue->last_thread= new_list; } /* Add thread and wait SYNOPSIS wqueue_add_and_wait() wqueue queue to add to thread thread which is waiting lock mutex need for the operation */ void wqueue_add_and_wait(WQUEUE *wqueue, struct st_my_thread_var *thread, mysql_mutex_t *lock) { DBUG_ENTER("wqueue_add_and_wait"); DBUG_PRINT("enter", ("thread: %p cond: %p mutex: %p", thread, &thread->suspend, lock)); wqueue_add_to_queue(wqueue, thread); do { DBUG_PRINT("info", ("wait... cond: %p mutex: %p", &thread->suspend, lock)); mysql_cond_wait(&thread->suspend, lock); DBUG_PRINT("info", ("wait done cond: %p mutex: %p next: %p", &thread->suspend, lock, thread->next)); } while (thread->next); DBUG_VOID_RETURN; }