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