2 * Copyright (C) 2004-2007, 2011, 2012 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2001 Internet Software Consortium.
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20 #ifndef ISC_TASKPOOL_H
21 #define ISC_TASKPOOL_H 1
27 /*! \file isc/taskpool.h
28 * \brief A task pool is a mechanism for sharing a small number of tasks
29 * among a large number of objects such that each object is
30 * assigned a unique task, but each task may be shared by several
33 * Task pools are used to let objects that can exist in large
34 * numbers (e.g., zones) use tasks for synchronization without
35 * the memory overhead and unfair scheduling competition that
36 * could result from creating a separate task for each object.
53 typedef struct isc_taskpool isc_taskpool_t;
60 isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx,
61 unsigned int ntasks, unsigned int quantum,
62 isc_taskpool_t **poolp);
64 * Create a task pool of "ntasks" tasks, each with quantum
69 *\li 'tmgr' is a valid task manager.
71 *\li 'mctx' is a valid memory context.
73 *\li poolp != NULL && *poolp == NULL
77 *\li On success, '*taskp' points to the new task pool.
83 *\li #ISC_R_UNEXPECTED
87 isc_taskpool_gettask(isc_taskpool_t *pool, isc_task_t **targetp);
89 * Attach to a task from the pool. Currently the next task is chosen
90 * from the pool at random. (This may be changed in the future to
91 * something that guaratees balance.)
95 isc_taskpool_size(isc_taskpool_t *pool);
97 * Returns the number of tasks in the task pool 'pool'.
101 isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
102 isc_taskpool_t **targetp);
105 * If 'size' is larger than the number of tasks in the pool pointed to by
106 * 'sourcep', then a new taskpool of size 'size' is allocated, the existing
107 * tasks from are moved into it, additional tasks are created to bring the
108 * total number up to 'size', and the resulting pool is attached to
111 * If 'size' is less than or equal to the tasks in pool 'source', then
112 * 'sourcep' is attached to 'targetp' without any other action being taken.
114 * In either case, 'sourcep' is detached.
118 * \li 'sourcep' is not NULL and '*source' is not NULL
119 * \li 'targetp' is not NULL and '*source' is NULL
123 * \li On success, '*targetp' points to a valid task pool.
124 * \li On success, '*sourcep' points to NULL.
129 * \li #ISC_R_NOMEMORY
133 isc_taskpool_destroy(isc_taskpool_t **poolp);
135 * Destroy a task pool. The tasks in the pool are detached but not
139 * \li '*poolp' is a valid task pool.
143 isc_taskpool_setprivilege(isc_taskpool_t *pool, isc_boolean_t priv);
145 * Set the privilege flag on all tasks in 'pool' to 'priv'. If 'priv' is
146 * true, then when the task manager is set into privileged mode, only
147 * tasks wihin this pool will be able to execute. (Note: It is important
148 * to turn the pool tasks' privilege back off before the last task finishes
152 * \li 'pool' is a valid task pool.
157 #endif /* ISC_TASKPOOL_H */