一个mysql客户端项目中，所有的参数都保存到mysql中，需要频繁的访问mysql server，其实使用一个mysql长连接也可以满足要求，但为了更好的利用多核CPU尝试使用连接池来充分发挥多线程的优势(电脑配置 i7-4核8线程)。
下面是mysql_pool实现的源码，
1. 头文件 mysql_pool.h
1 //
2 // 创建人： levy
3 // 创建时间：Jun 5, 2017
4 // 功能：mysql_pool.h
5 // Copyright (c) 2017 levy. All Rights Reserved.
6 // Ver 变更日期 负责人 变更内容
7 // ──────────────────────────────────────────────────────────────────────────
8 // V0.01 Jun 5, 2017 levy 初版
9 //
10
11
12 #ifndef MYSQL_POOL_H_
13 #define MYSQL_POOL_H_
14 #include <mysql.h>
15 #include <pthread.h>
16 #define MAX_KEPP_CONNECTIONS 8
17 typedef struct mysql_conn //mysql连接链表结构体定义
18 {
19 struct mysql_conn * next;
20 struct mysql_conn * prev;
21 MYSQL conn;
22
23 }mysql_conn;
24
25 typedef struct mysql_pool //mysql连接池结构体定义
26 {
27 char host[64]; //主机名称
28 char username[32]; //用户名
29 char passwd[32]; //密码
30 char database[32]; //默认数据库
31 int s_port; //端口号，默认3306
32 int max_connections; //保持开启的mysql最大连接数
33 int free_connections; //当前空闲的mysql连接数
34 int is_idle_block; //是否开启了无可用连接阻塞
35 pthread_mutex_t lock; //mysql链表锁
36 pthread_cond_t idle_signal; //等待可用连接的条件变量
37 mysql_conn * mysql_list; //mysql连接池链表
38 }mysql_pool;
39
40 void mysql_pool_init();
41 void destory_mysql_pool();
42 void destory_mysql_connection(mysql_conn *conn);
43 void release_mysql_connection(mysql_conn *conn);
44 mysql_conn * get_mysql_connection();
45
46 MYSQL_RES* mysql_execute_query(const char *sql,unsigned long length,int *flag);
47
48 #endif /* MYSQL_POOL_H_ */
2.连接池实现 1 //
2 // 创建人： levy
3 // 创建时间：Jun 5, 2017
4 // 功能：mysql_pool.c
5 // Copyright (c) 2016 levy. All Rights Reserved.
6 // Ver 变更日期 负责人 变更内容
7 // ──────────────────────────────────────────────────────────────────────────
8 // V0.01 Jun 5, 2017 levy 初版
9 //
10
11 #include "mysql_pool.h"
12 #include <stdlib.h>
13 #include <string.h>
14 #include <errno.h>
15 #include <stdio.h>
16 static mysql_pool pool_mysql;//连接池定义
17 unsigned int query_times = 0;//mysql所有的查询次数，用于测试
18
19 /*创建一个新的mysql连接
20 * @return NULL代表创建失败。
21 */
22 mysql_conn * mysql_new_connection()
23 {
24 mysql_conn * conn=malloc(sizeof(mysql_conn));
25 if(mysql_init(&conn->conn)==NULL)
26 {
27 printf("can not init mysql: [%s]\n",strerror(errno));
28 free(conn);
29 return NULL;
30 }
31 if(mysql_options(&conn->conn, MYSQL_SET_CHARSET_NAME, "UTF8")!=0)
32 {
33 printf("can not set mysql options[errno = %d]: [%s]\n",mysql_errno(&conn->conn),mysql_error(&conn->conn));
34 free(conn);
35 return NULL;
36 }
37 //连接到mysql服务端，设置CLIENT_MULTI_STATEMENTS通知服务器客户端可以处理由多语句或者存储过程执行生成的多结果集
38 if(mysql_real_connect(&conn->conn,pool_mysql.host,pool_mysql.username,pool_mysql.passwd,pool_mysql.database,pool_mysql.s_port,NULL, CLIENT_MULTI_STATEMENTS)==NULL)
39 {
40 printf("can not connect mysql server[errno = %d]: [%s]\n",mysql_errno(&conn->conn),mysql_error(&conn->conn));
41 free(conn);
42 return NULL;
43 }
44 conn->next = NULL;
45 conn->prev = NULL;
46 return conn;
47 }
48
49 /*向链接池中压入一个mysql连接conn
50 * */
51 void conn_push(mysql_conn * conn)
52 {
53 mysql_conn *lc = pool_mysql.mysql_list;
54 if(lc==NULL)
55 {
56 pool_mysql.mysql_list=conn;
57
58 }else
59 {
60 while(lc->next)
61 {
62 lc=lc->next;
63 }
64 lc->next = conn;
65 conn->prev = lc;
66
67 }
68 pool_mysql.free_connections++;
69 }
70
71 /*从连接池中出栈一个mysql连接
72 * @return NULL表示连接池中没有可用的连接
73 * */
74 mysql_conn * conn_pop()
75 {
76 mysql_conn*conn = pool_mysql.mysql_list;
77 if(conn != NULL)
78 {
79
80 pool_mysql.mysql_list = conn->next;
81 if(pool_mysql.mysql_list)
82 {
83 pool_mysql.mysql_list->prev = NULL;
84 }
85 pool_mysql.free_connections--;
86 }
87 return conn;
88 }
89
90 /*初始化mysql连接池*/
91 void mysql_pool_init()
92 {
93 mysql_conn * conn;
94 strncpy(pool_mysql.host,"localhost",sizeof(pool_mysql.host));
95 strncpy(pool_mysql.username,"test",sizeof(pool_mysql.username));
96 strncpy(pool_mysql.passwd,"test",sizeof(pool_mysql.passwd));
97 strncpy(pool_mysql.database,"test",sizeof(pool_mysql.database));
98 pool_mysql.s_port = 3306;
99 pool_mysql.max_connections=MAX_KEEP_CONNECTIONS;
100 pool_mysql.free_connections = 0;
101 pool_mysql.mysql_list = NULL;
102 pool_mysql.is_idle_block = 0;
103 pthread_mutex_init(&pool_mysql.lock,NULL);
104 pthread_cond_init(&pool_mysql.idle_signal,NULL);
105 pthread_mutex_lock(&pool_mysql.lock);
106 for(int i=0;i<pool_mysql.max_connections;i++)
107 {
108 conn=mysql_new_connection();
109 if(conn)
110 {
111 conn_push(conn);
112 }else
113 {
114
115 }
116
117 }
118 pthread_mutex_unlock(&pool_mysql.lock);
119 }
120
121 /*从连接池中获取一个mysql连接*/
122 mysql_conn * get_mysql_connection()
123 {
124 pthread_mutex_lock(&pool_mysql.lock);
125 mysql_conn *conn = conn_pop();
126 pthread_mutex_unlock(&pool_mysql.lock);
127 return conn;
128 }
129
130 /*从连接池中获取一个mysql连接，如果连接池为空，测阻塞*/
131 mysql_conn * get_mysql_connection_block()
132 {
133 pthread_mutex_lock(&pool_mysql.lock);
134 mysql_conn *conn = conn_pop();
135 while(conn == NULL)
136 {
137 pool_mysql.is_idle_block ++;
138 pthread_cond_wait(&pool_mysql.idle_signal,&pool_mysql.lock);
139 conn = conn_pop();
140 pool_mysql.is_idle_block --;
141 }
142 query_times++;
143 pthread_mutex_unlock(&pool_mysql.lock);
144 return conn;
145 }
146
147
148 /*回收一个mysql连接到连接池*/
149 void release_mysql_connection(mysql_conn *conn)
150 {
151 pthread_mutex_lock(&pool_mysql.lock);
152 conn->next = NULL;
153 conn->prev = NULL;
154 conn_push(conn);
155 if(pool_mysql.is_idle_block)
156 {
157 pthread_cond_signal(&pool_mysql.idle_signal);
158 }
159 pthread_mutex_unlock(&pool_mysql.lock);
160 }
161
162 /*销毁一个mysql连接，并释放其占用的资源*/
163 void destory_mysql_connection(mysql_conn *conn)
164 {
165 mysql_close(&conn->conn);
166 free(conn);
167 }
168
169 //销毁连接池中的所有连接
170 void destory_mysql_pool()
171 {
172 mysql_conn *conn;
173 pthread_mutex_lock(&pool_mysql.lock);
174 conn = conn_pop();
175 for(;conn;conn = conn_pop())
176 {
177 destory_mysql_connection(conn);
178 }
179 pthread_mutex_unlock(&pool_mysql.lock);
180 }
181
182
183 MYSQL_RES* mysql_execute_query(const char *sql,unsigned long length,int *flag)
184 {
185 int res;
186 MYSQL_RES *res_ptr;
187 mysql_conn*con = get_mysql_connection_block();
188 if(con == NULL)
189 {
190 printf("can not get mysql connections from the pools\n");
191 *flag =-2;
192 return NULL;
193 }
194 *flag=0;
195 res=mysql_real_query(&con->conn,sql,length);
196 if(res!=0)
197 {
198 printf("mysql_real_query error [errno = %d]: [%s]\n",mysql_errno(&con->conn),mysql_error(&con->conn));
199 release_mysql_connection(con);
200 *flag=res;
201 return NULL;
202 }
203 res_ptr = mysql_store_result(&con->conn);
204 if(res_ptr == NULL)
205 {
206 printf("mysql_store_result error [errno = %d]: [%s]\n",mysql_errno(&con->conn),mysql_error(&con->conn));
207 }
208 release_mysql_connection(con);
209 return res_ptr;
210 }
2113.测试主函数main.c，同时创建10000个线程 1 2 // 创建人： levy
3 // 创建时间：May 25, 2017
4 // 功能：main.c
5 // Copyright (c) 2016 levy. All Rights Reserved.
6 // Ver 变更日期 负责人 变更内容
7 // ──────────────────────────────────────────────────────────────────────────
8 // V0.01 May 25, 2017 levy 初版
9 //
10
11 #include <stdlib.h>
12 #include <stdio.h>
13 #include <unistd.h>
14 #include <time.h>
15 #include <sys/time.h>
16 #include <pthread.h>
17 #include <string.h>
18 #include <errno.h>
19 #include "mysql_pool.h"
20
21 const char *test_sql = "SELECT ID,Name,Value,RecordTime FROM test where ID <1024";
22 extern unsigned int query_times ;
23
24
25 void * test_thread(void *arp)
26 {
27 int flag=0;
28 int count=0;
29 MYSQL_RES * resptr;
30 //for(int i=0;i<10;i++)
31 {
32 resptr=mysql_execute_query(test_sql,strlen(test_sql),&flag);
33 if(resptr)
34 {
35 count++;
36 mysql_free_result(resptr);
37 }else
38 {
39 perror("error");
40 }
41 }
42 //printf("I has finsh %d query.\n",count);
43 pthread_exit(NULL);
44 }
45
46
47
48 #define thread_nums 10000
49 int main(void )
50 {
51 mysql_pool_init();
52 pthread_t th[thread_nums];
53 struct timeval tnow,tnow1,tnow2;
54 gettimeofday(&tnow1, NULL);
55 printf("start time tv_sec = %ld,tv_usec = %ld \n",tnow1.tv_sec,tnow1.tv_usec);
56 for(int i=0;i<thread_nums;i++)
57 {
58 pthread_create(&th[i],NULL,test_thread,NULL);
59 }
60 for(int i=0;i<thread_nums;i++)
61 {
62 pthread_join(th[i],NULL);
63 }
64 gettimeofday(&tnow2, NULL);
65 timersub(&tnow2,&tnow1,&tnow);
66 printf("Max keep connections = %d,max_thread_nums=%d,total query times=%d,use %ld ms",MAX_KEPP_CONNECTIONS,thread_nums,query_times,tnow.tv_sec*1000+tnow.tv_usec/1000);
67 //printf("total time tv_sec = %ld.%3ld s \n",);
68 destory_mysql_pool();
69 pthread_exit(NULL);
70 }
测试结果
1.Max keep connections = 1,max_thread_nums=10000,total query times=10000,use 6114 ms
2.Max keep connections = 2,max_thread_nums=10000,total query times=10000,use 3404 ms
3.Max keep connections = 4,max_thread_nums=10000,total query times=10000,use 1958 ms
4.Max keep connections = 8,max_thread_nums=10000,total query times=10000,use 1794 ms
5.Max keep connections = 16,max_thread_nums=10000,total query times=10000,use 1787 ms
总结：从测试结果可以看出保持最大连接数目为cpu的核心数能够充分发挥cpu多核的优势。
编辑日期：2017-06-05 16:55:39