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1 | /* |
2 | * Copyright (C) 2017 Oracle. All Rights Reserved. | |
3 | * | |
4 | * Author: Darrick J. Wong <darrick.wong@oracle.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version 2 | |
9 | * of the License, or (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it would be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write the Free Software Foundation, | |
18 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. | |
19 | * | |
20 | * This code was adapted from repair/threads.c, which (at the time) | |
21 | * did not contain a copyright statement. | |
22 | */ | |
23 | #include <pthread.h> | |
24 | #include <signal.h> | |
25 | #include <stdlib.h> | |
26 | #include <string.h> | |
27 | #include <stdint.h> | |
28 | #include <stdbool.h> | |
29 | #include <errno.h> | |
30 | #include <assert.h> | |
31 | #include "workqueue.h" | |
32 | ||
33 | /* Main processing thread */ | |
34 | static void * | |
35 | workqueue_thread(void *arg) | |
36 | { | |
37 | struct workqueue *wq = arg; | |
38 | struct workqueue_item *wi; | |
39 | ||
40 | /* | |
41 | * Loop pulling work from the passed in work queue. | |
42 | * Check for notification to exit after every chunk of work. | |
43 | */ | |
44 | while (1) { | |
45 | pthread_mutex_lock(&wq->lock); | |
46 | ||
47 | /* | |
48 | * Wait for work. | |
49 | */ | |
50 | while (wq->next_item == NULL && !wq->terminate) { | |
51 | assert(wq->item_count == 0); | |
52 | pthread_cond_wait(&wq->wakeup, &wq->lock); | |
53 | } | |
54 | if (wq->next_item == NULL && wq->terminate) { | |
55 | pthread_mutex_unlock(&wq->lock); | |
56 | break; | |
57 | } | |
58 | ||
59 | /* | |
60 | * Dequeue work from the head of the list. | |
61 | */ | |
62 | assert(wq->item_count > 0); | |
63 | wi = wq->next_item; | |
64 | wq->next_item = wi->next; | |
65 | wq->item_count--; | |
66 | ||
67 | pthread_mutex_unlock(&wq->lock); | |
68 | ||
69 | (wi->function)(wi->queue, wi->index, wi->arg); | |
70 | free(wi); | |
71 | } | |
72 | ||
73 | return NULL; | |
74 | } | |
75 | ||
76 | /* Allocate a work queue and threads. */ | |
77 | int | |
78 | workqueue_create( | |
79 | struct workqueue *wq, | |
80 | void *wq_ctx, | |
81 | unsigned int nr_workers) | |
82 | { | |
83 | unsigned int i; | |
84 | int err = 0; | |
85 | ||
86 | memset(wq, 0, sizeof(*wq)); | |
87 | pthread_cond_init(&wq->wakeup, NULL); | |
88 | pthread_mutex_init(&wq->lock, NULL); | |
89 | ||
90 | wq->wq_ctx = wq_ctx; | |
91 | wq->thread_count = nr_workers; | |
92 | wq->threads = malloc(nr_workers * sizeof(pthread_t)); | |
93 | wq->terminate = false; | |
94 | ||
95 | for (i = 0; i < nr_workers; i++) { | |
96 | err = pthread_create(&wq->threads[i], NULL, workqueue_thread, | |
97 | wq); | |
98 | if (err) | |
99 | break; | |
100 | } | |
101 | ||
102 | if (err) | |
103 | workqueue_destroy(wq); | |
104 | return err; | |
105 | } | |
106 | ||
107 | /* | |
108 | * Create a work item consisting of a function and some arguments and | |
109 | * schedule the work item to be run via the thread pool. | |
110 | */ | |
111 | int | |
112 | workqueue_add( | |
113 | struct workqueue *wq, | |
114 | workqueue_func_t func, | |
115 | uint32_t index, | |
116 | void *arg) | |
117 | { | |
118 | struct workqueue_item *wi; | |
119 | ||
120 | if (wq->thread_count == 0) { | |
121 | func(wq, index, arg); | |
122 | return 0; | |
123 | } | |
124 | ||
125 | wi = malloc(sizeof(struct workqueue_item)); | |
126 | if (wi == NULL) | |
127 | return ENOMEM; | |
128 | ||
129 | wi->function = func; | |
130 | wi->index = index; | |
131 | wi->arg = arg; | |
132 | wi->queue = wq; | |
133 | wi->next = NULL; | |
134 | ||
135 | /* Now queue the new work structure to the work queue. */ | |
136 | pthread_mutex_lock(&wq->lock); | |
137 | if (wq->next_item == NULL) { | |
138 | wq->next_item = wi; | |
139 | assert(wq->item_count == 0); | |
140 | pthread_cond_signal(&wq->wakeup); | |
141 | } else { | |
142 | wq->last_item->next = wi; | |
143 | } | |
144 | wq->last_item = wi; | |
145 | wq->item_count++; | |
146 | pthread_mutex_unlock(&wq->lock); | |
147 | ||
148 | return 0; | |
149 | } | |
150 | ||
151 | /* | |
152 | * Wait for all pending work items to be processed and tear down the | |
153 | * workqueue. | |
154 | */ | |
155 | void | |
156 | workqueue_destroy( | |
157 | struct workqueue *wq) | |
158 | { | |
159 | unsigned int i; | |
160 | ||
161 | pthread_mutex_lock(&wq->lock); | |
162 | wq->terminate = 1; | |
163 | pthread_mutex_unlock(&wq->lock); | |
164 | ||
165 | pthread_cond_broadcast(&wq->wakeup); | |
166 | ||
167 | for (i = 0; i < wq->thread_count; i++) | |
168 | pthread_join(wq->threads[i], NULL); | |
169 | ||
170 | free(wq->threads); | |
171 | pthread_mutex_destroy(&wq->lock); | |
172 | pthread_cond_destroy(&wq->wakeup); | |
173 | memset(wq, 0, sizeof(*wq)); | |
174 | } |