1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2013 Olaf Wintermann. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32
33 #include "atomic.h"
34 #include "thrpool.h"
35
36 static threadpool_job kill_job;
37
38 threadpool_t* threadpool_new(int min, int max) {
39 log_ereport(LOG_VERBOSE, "new threadpool (min: %d, max: %d)", min, max);
40 threadpool_t *pool = malloc(sizeof(threadpool_t));
41 pool->queue = NULL;
42 pool->queue_len = 0;
43 pool->num_idle = 0;
44 pool->min_threads = min;
45 pool->max_threads = max;
46 pool->num_threads = 0;
47
48 pthread_mutex_init(&pool->queue_lock, NULL);
49 pthread_mutex_init(&pool->avlbl_lock, NULL);
50 pthread_cond_init(&pool->available, NULL);
51
52 /* create pool threads */
53 for(int i=0;i<min;i++) {
54 pthread_t t;
55 if (pthread_create(&t, NULL, threadpool_func, pool) != 0) {
56 perror("Error: threadpool_new: pthread_create");
57 return NULL;
58 }
59 }
60
61 return pool;
62 }
63
64 void* threadpool_func(void *data) {
65 threadpool_t *pool = (threadpool_t*)data;
66
67 ws_atomic_inc32(&pool->num_threads);
68 for(;;) {
69 threadpool_job *job = threadpool_get_job(pool);
70 if(job == &kill_job) {
71 break;
72 }
73
74 job->callback(job->data);
75
76 free(job);
77 }
78 ws_atomic_dec32(&pool->num_threads);
79 return NULL;
80 }
81
82 threadpool_job* threadpool_get_job(threadpool_t *pool) {
83 pthread_mutex_lock(&pool->queue_lock);
84
85 threadpool_job *job = NULL;
86 pool->num_idle++;
87 while(job == NULL) {
88 if(pool->queue_len == 0) {
89 pthread_cond_wait(&pool->available, &pool->queue_lock);
90 continue;
91 } else {
92 pool_queue_t *q = pool->queue;
93 job = q->job;
94 pool->queue = q->next;
95 pool->queue_len--;
96 free(q);
97 }
98 }
99 pool->num_idle--;
100
101 pthread_mutex_unlock(&pool->queue_lock);
102 return job;
103 }
104
105 void threadpool_run(threadpool_t *pool, job_callback_f func, void *data) {
106 threadpool_job *job = malloc(sizeof(threadpool_job));
107 job->callback = func;
108 job->data = data;
109
110 pthread_mutex_lock(&pool->queue_lock);
111 threadpool_enqueue_job(pool, job);
112
113 int create_thread = 0;
114 int destroy_thread = 0;
115 int diff = pool->queue_len - pool->num_idle;
116 if(diff > 0 && pool->num_threads < pool->max_threads) {
117 create_thread = 1;
118 } else if(diff < 0 && pool->num_threads > pool->min_threads) {
119 destroy_thread = 1;
120 }
121
122 //if(pool->queue_len == 1) {
123 pthread_cond_signal(&pool->available);
124 //}
125
126 if(create_thread) {
127 pthread_t t;
128 if (pthread_create(&t, NULL, threadpool_func, pool) != 0) {
129 perror("Error: threadpool_run: pthread_create");
130 }
131 }
132 if(destroy_thread) {
133 threadpool_enqueue_job(pool, &kill_job);
134 pthread_cond_signal(&pool->available);
135 }
136
137 pthread_mutex_unlock(&pool->queue_lock);
138 }
139
140 void threadpool_enqueue_job(threadpool_t *pool, threadpool_job *job) {
141 pool_queue_t *q = malloc(sizeof(pool_queue_t));
142 q->job = job;
143 q->next = NULL;
144
145 if(pool->queue == NULL) {
146 pool->queue = q;
147 } else {
148 pool_queue_t *last_elem = pool->queue;
149 while(last_elem->next != NULL) {
150 last_elem = last_elem->next;
151 }
152 last_elem->next = q;
153 }
154 pool->queue_len++;
155 }
156