/***************************************************************************** Copyright (c) 2006, 2015, Oracle and/or its affiliates. All Rights Reserved. Copyright (c) 2019, MariaDB Corporation. 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 02110-1335 USA *****************************************************************************/ #include "ut0list.h" #include "mem0mem.h" #include "ut0wqueue.h" /*******************************************************************//** @file ut/ut0wqueue.cc A work queue Created 4/26/2006 Osku Salerma ************************************************************************/ /* Work queue. */ struct ib_wqueue_t { ib_mutex_t mutex; /*!< mutex protecting everything */ ib_list_t* items; /*!< work item list */ os_event_t event; /*!< event we use to signal additions to list; os_event_set() and os_event_reset() are protected by ib_wqueue_t::mutex */ }; /****************************************************************//** Create a new work queue. @return work queue */ ib_wqueue_t* ib_wqueue_create(void) /*===================*/ { ib_wqueue_t* wq = static_cast<ib_wqueue_t*>( ut_malloc_nokey(sizeof(*wq))); /* Function ib_wqueue_create() has not been used anywhere, not necessary to instrument this mutex */ mutex_create(LATCH_ID_WORK_QUEUE, &wq->mutex); wq->items = ib_list_create(); wq->event = os_event_create(0); return(wq); } /****************************************************************//** Free a work queue. */ void ib_wqueue_free( /*===========*/ ib_wqueue_t* wq) /*!< in: work queue */ { mutex_free(&wq->mutex); ib_list_free(wq->items); os_event_destroy(wq->event); ut_free(wq); } /****************************************************************//** Add a work item to the queue. */ void ib_wqueue_add( /*==========*/ ib_wqueue_t* wq, /*!< in: work queue */ void* item, /*!< in: work item */ mem_heap_t* heap) /*!< in: memory heap to use for allocating the list node */ { mutex_enter(&wq->mutex); ib_list_add_last(wq->items, item, heap); os_event_set(wq->event); mutex_exit(&wq->mutex); } /****************************************************************//** Wait for a work item to appear in the queue. @return work item */ void* ib_wqueue_wait( /*===========*/ ib_wqueue_t* wq) /*!< in: work queue */ { ib_list_node_t* node; for (;;) { os_event_wait(wq->event); mutex_enter(&wq->mutex); node = ib_list_get_first(wq->items); if (node) { ib_list_remove(wq->items, node); if (!ib_list_get_first(wq->items)) { /* We must reset the event when the list gets emptied. */ os_event_reset(wq->event); } break; } mutex_exit(&wq->mutex); } mutex_exit(&wq->mutex); return(node->data); } /******************************************************************** Wait for a work item to appear in the queue for specified time. */ void* ib_wqueue_timedwait( /*================*/ /* out: work item or NULL on timeout*/ ib_wqueue_t* wq, /* in: work queue */ ib_time_t wait_in_usecs) /* in: wait time in micro seconds */ { ib_list_node_t* node = NULL; for (;;) { ulint error; int64_t sig_count; mutex_enter(&wq->mutex); node = ib_list_get_first(wq->items); if (node) { ib_list_remove(wq->items, node); mutex_exit(&wq->mutex); break; } sig_count = os_event_reset(wq->event); mutex_exit(&wq->mutex); error = os_event_wait_time_low(wq->event, (ulint) wait_in_usecs, sig_count); if (error == OS_SYNC_TIME_EXCEEDED) { break; } } return(node ? node->data : NULL); } /******************************************************************** Return first item on work queue or NULL if queue is empty @return work item or NULL */ void* ib_wqueue_nowait( /*=============*/ ib_wqueue_t* wq) /*<! in: work queue */ { ib_list_node_t* node = NULL; mutex_enter(&wq->mutex); if(!ib_list_is_empty(wq->items)) { node = ib_list_get_first(wq->items); if (node) { ib_list_remove(wq->items, node); } } /* We must reset the event when the list gets emptied. */ if(ib_list_is_empty(wq->items)) { os_event_reset(wq->event); } mutex_exit(&wq->mutex); return (node ? node->data : NULL); } /** Check if queue is empty. @param wq wait queue @return whether the queue is empty */ bool ib_wqueue_is_empty(ib_wqueue_t* wq) { mutex_enter(&wq->mutex); bool is_empty = ib_list_is_empty(wq->items); mutex_exit(&wq->mutex); return is_empty; } /******************************************************************** Get number of items on queue. @return number of items on queue */ ulint ib_wqueue_len( /*==========*/ ib_wqueue_t* wq) /*<! in: work queue */ { ulint len = 0; mutex_enter(&wq->mutex); len = ib_list_len(wq->items); mutex_exit(&wq->mutex); return(len); }