taskpool.h revision 290001 
1/*
2 * Copyright (C) 2004-2007, 2011, 2012  Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2001  Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/* $Id$ */
19
20#ifndef ISC_TASKPOOL_H
21#define ISC_TASKPOOL_H 1
22
23/*****
24 ***** Module Info
25 *****/
26
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
31 * objects.
32 *
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.
37 */
38
39
40/***
41 *** Imports.
42 ***/
43
44#include <isc/lang.h>
45#include <isc/task.h>
46
47ISC_LANG_BEGINDECLS
48
49/*****
50 ***** Types.
51 *****/
52
53typedef struct isc_taskpool isc_taskpool_t;
54
55/*****
56 ***** Functions.
57 *****/
58
59isc_result_t
60isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx,
61		    unsigned int ntasks, unsigned int quantum,
62		    isc_taskpool_t **poolp);
63/*%<
64 * Create a task pool of "ntasks" tasks, each with quantum
65 * "quantum".
66 *
67 * Requires:
68 *
69 *\li	'tmgr' is a valid task manager.
70 *
71 *\li	'mctx' is a valid memory context.
72 *
73 *\li	poolp != NULL && *poolp == NULL
74 *
75 * Ensures:
76 *
77 *\li	On success, '*taskp' points to the new task pool.
78 *
79 * Returns:
80 *
81 *\li	#ISC_R_SUCCESS
82 *\li	#ISC_R_NOMEMORY
83 *\li	#ISC_R_UNEXPECTED
84 */
85
86void
87isc_taskpool_gettask(isc_taskpool_t *pool, isc_task_t **targetp);
88/*%<
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.)
92 */
93
94int
95isc_taskpool_size(isc_taskpool_t *pool);
96/*%<
97 * Returns the number of tasks in the task pool 'pool'.
98 */
99
100isc_result_t
101isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
102					isc_taskpool_t **targetp);
103
104/*%<
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
109 * 'targetp'.
110 *
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.
113 *
114 * In either case, 'sourcep' is detached.
115 *
116 * Requires:
117 *
118 * \li	'sourcep' is not NULL and '*source' is not NULL
119 * \li	'targetp' is not NULL and '*source' is NULL
120 *
121 * Ensures:
122 *
123 * \li	On success, '*targetp' points to a valid task pool.
124 * \li	On success, '*sourcep' points to NULL.
125 *
126 * Returns:
127 *
128 * \li	#ISC_R_SUCCESS
129 * \li	#ISC_R_NOMEMORY
130 */
131
132void
133isc_taskpool_destroy(isc_taskpool_t **poolp);
134/*%<
135 * Destroy a task pool.  The tasks in the pool are detached but not
136 * shut down.
137 *
138 * Requires:
139 * \li	'*poolp' is a valid task pool.
140 */
141
142void
143isc_taskpool_setprivilege(isc_taskpool_t *pool, isc_boolean_t priv);
144/*%<
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
149 * executing.)
150 *
151 * Requires:
152 * \li	'pool' is a valid task pool.
153 */
154
155ISC_LANG_ENDDECLS
156
157#endif /* ISC_TASKPOOL_H */
158