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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#ifndef ISC_TASKPOOL_H
#define ISC_TASKPOOL_H 1
/*****
***** Module Info
*****/
/*! \file isc/taskpool.h
* \brief A task pool is a mechanism for sharing a small number of tasks
* among a large number of objects such that each object is
* assigned a unique task, but each task may be shared by several
* objects.
*
* Task pools are used to let objects that can exist in large
* numbers (e.g., zones) use tasks for synchronization without
* the memory overhead and unfair scheduling competition that
* could result from creating a separate task for each object.
*/
/***
*** Imports.
***/
#include <stdbool.h>
#include <isc/lang.h>
#include <isc/task.h>
ISC_LANG_BEGINDECLS
/*****
***** Types.
*****/
typedef struct isc_taskpool isc_taskpool_t;
/*****
***** Functions.
*****/
isc_result_t
isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx,
unsigned int ntasks, unsigned int quantum,
isc_taskpool_t **poolp);
/*%<
* Create a task pool of "ntasks" tasks, each with quantum
* "quantum".
*
* Requires:
*
*\li 'tmgr' is a valid task manager.
*
*\li 'mctx' is a valid memory context.
*
*\li poolp != NULL && *poolp == NULL
*
* Ensures:
*
*\li On success, '*taskp' points to the new task pool.
*
* Returns:
*
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*\li #ISC_R_UNEXPECTED
*/
void
isc_taskpool_gettask(isc_taskpool_t *pool, isc_task_t **targetp);
/*%<
* Attach to a task from the pool. Currently the next task is chosen
* from the pool at random. (This may be changed in the future to
* something that guaratees balance.)
*/
int
isc_taskpool_size(isc_taskpool_t *pool);
/*%<
* Returns the number of tasks in the task pool 'pool'.
*/
isc_result_t
isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
isc_taskpool_t **targetp);
/*%<
* If 'size' is larger than the number of tasks in the pool pointed to by
* 'sourcep', then a new taskpool of size 'size' is allocated, the existing
* tasks from are moved into it, additional tasks are created to bring the
* total number up to 'size', and the resulting pool is attached to
* 'targetp'.
*
* If 'size' is less than or equal to the tasks in pool 'source', then
* 'sourcep' is attached to 'targetp' without any other action being taken.
*
* In either case, 'sourcep' is detached.
*
* Requires:
*
* \li 'sourcep' is not NULL and '*source' is not NULL
* \li 'targetp' is not NULL and '*source' is NULL
*
* Ensures:
*
* \li On success, '*targetp' points to a valid task pool.
* \li On success, '*sourcep' points to NULL.
*
* Returns:
*
* \li #ISC_R_SUCCESS
* \li #ISC_R_NOMEMORY
*/
void
isc_taskpool_destroy(isc_taskpool_t **poolp);
/*%<
* Destroy a task pool. The tasks in the pool are detached but not
* shut down.
*
* Requires:
* \li '*poolp' is a valid task pool.
*/
void
isc_taskpool_setprivilege(isc_taskpool_t *pool, bool priv);
/*%<
* Set the privilege flag on all tasks in 'pool' to 'priv'. If 'priv' is
* true, then when the task manager is set into privileged mode, only
* tasks wihin this pool will be able to execute. (Note: It is important
* to turn the pool tasks' privilege back off before the last task finishes
* executing.)
*
* Requires:
* \li 'pool' is a valid task pool.
*/
ISC_LANG_ENDDECLS
#endif /* ISC_TASKPOOL_H */
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