1、概述
池化技术，减少了资源创建次数，提高了程序响应性能，特别是在高并发场景下，当程序7*24小时运行，创建资源可能会出现耗时较长和失败等问题，池化技术，主要是程序初始化之前创建多个可用连接，集中管理起来，后续直接使用，使用完并归还。
2、线程池
线程池主要解决问题：
1、解决线程创建和消耗所浪费的资源和时间
2、控制线程数量，减少资源竞争
代码解读
一共由三个接口组成：
1、CreatePthreadPool创建工作线程
初始化线程池结构下的条件变量和互斥锁，创建多个线程通过头插法，插入到线程池结构worker成员中
2、thread_func线程入口函数
进入while循环，第一件事先拿锁，然后再去判断，任务队列中是否有数据，要是没有则进入循环中的条件等待，进入条件等待会先释放锁，所以初始化完成之后所有线程全部都会进入条件等待，然后一旦条件满足则会去拿锁。
3、threadPoolQueue将任务加入到任务链表中
先加锁，然后通过头插法插入到线程池结构中的wait_jobs成员中，通知条件变量，然后解锁
4、threadPoolShutdown回收线程池中线程
将工作线程中的标识位全部置为一，然后通知所有线程，然后等待回收所有线程并释放每个节点
总结
线程池就是一个很典型的生产者消费者模型，不断地向任务队列中投放任务，工作线程不断地去队伍队列中去取任务消费掉。
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#define LL_ADD(item, list) do { \
item->prev = NULL; \
item->next = list; \
list = item; \
} while(0)
#define LL_REMOVE(item, list) do { \
if (item->prev != NULL) item->prev->next = item->next; \
if (item->next != NULL) item->next->prev = item->prev; \
if (list == item) list = item->next; \
item->prev = item->next = NULL; \
} while(0)
// 工作线程结构体
typedef struct NWORKER{
pthread_t id; // 线程id
int terminate; // 终止条件
struct NTHREADPOLL *worqueue;
struct NWORKER *prev; // 前向指针
struct NWORKER *next; // 后项指针
}nWorker;
// 任务队列
typedef struct NJOB{
void (*job_function)(struct NJOB* job);
void* user_data;
struct NJOB *prev;
struct NJOB *next;
}nJob;
typedef struct NTHREADPOLL{
struct NWORKER *workers;
struct NJOB *wait_jobs;
pthread_cond_t cond;
pthread_mutex_t mtx;
}nThreadpoll;
// 操作线程池函数
#define MAX_PTHREAD 80
#define MAX_JOB 8
// 毁掉函数
void job_fun(nJob *job){
if(job == NULL) return;
int *data = (int*)job->user_data;
printf("user_data:%d-thread_id:%ld,line:%d\n",*data,pthread_self(),__LINE__);
free(job->user_data);
job->user_data = NULL;
free(job);
job = NULL;
return;
}
// 线程入口函数
void* thread_func(void* data){
nWorker *worker = (nWorker*)data;
while (1)
{
pthread_mutex_lock(&(worker->worqueue->mtx));
while(worker->worqueue->wait_jobs == NULL){
if(worker->terminate) break;
pthread_cond_wait(&(worker->worqueue->cond),&(worker->worqueue->mtx));
}
if(worker->terminate){
pthread_mutex_unlock(&(worker->worqueue->mtx));
break;
}
nJob *job = worker->worqueue->wait_jobs;
if(job != NULL)
LL_REMOVE(job,worker->worqueue->wait_jobs);
pthread_mutex_unlock(&(worker->worqueue->mtx));
if(job == NULL) continue;
job->job_function(job);
}
// free(worker);
// worker = NULL;
pthread_exit(0);
}
// 创造线程
int CreatePthreadPool(nThreadpoll* threadpoll,int max_pthread)
{
if(max_pthread <= 0) max_pthread = MAX_PTHREAD;
memset(threadpoll,0x00,sizeof(nThreadpoll));
pthread_cond_t blank_cond = PTHREAD_COND_INITIALIZER;
memcpy(&threadpoll->cond, &blank_cond, sizeof(threadpoll->cond));
pthread_mutex_t blank_mutex = PTHREAD_MUTEX_INITIALIZER;
memcpy(&threadpoll->mtx, &blank_mutex, sizeof(threadpoll->mtx));
int i;
for(i=0; i<max_pthread; i++){
nWorker *worker = (nWorker*)malloc(sizeof(nWorker));
if(worker == NULL){
perror("threadpoll->workers");
return -1;
}
memset(worker,0x00,sizeof(nWorker));
worker->worqueue = threadpoll;
worker->terminate = 0;
int ret = pthread_create(&(worker->id),NULL,thread_func,(void*)worker);
if(ret != 0){
perror("pthread_create");
free(worker);
worker = NULL;
return -1;
}
LL_ADD(worker,worker->worqueue->workers);
}
return 0;
}
// 向线程中添加任务，唤醒一个线程去处理
void threadPoolQueue(nThreadpoll* threadpool,nJob *job){
pthread_mutex_lock(&(threadpool->mtx));
LL_ADD(job,threadpool->wait_jobs);
pthread_cond_signal(&(threadpool->cond));
pthread_mutex_unlock(&(threadpool->mtx));
return;
}
void threadPoolShutdown(nThreadpoll *workerqueue){
nWorker *woker = NULL;
for(woker = workerqueue->workers;woker!=NULL;woker = woker->next){
woker->terminate = 1;
}
pthread_cond_broadcast(&workerqueue->cond);
struct NWORKER *tmp = workerqueue->workers;
while (tmp)
{
pthread_join(tmp->id,NULL);
if(tmp){
free(tmp);
tmp = NULL;
}
tmp = tmp->next;
}
pthread_cond_destroy(&workerqueue->cond);
pthread_mutex_destroy(&workerqueue->mtx);
workerqueue->workers = NULL;
workerqueue->wait_jobs = NULL;
}
int main(){
nThreadpoll workerQueue;
if(CreatePthreadPool(&workerQueue,MAX_PTHREAD) != 0){
perror("CreatePthreadPool faile");
return -1;
}
int i;
for(i=0;i<MAX_JOB;i++){
nJob *job = (nJob*)malloc(sizeof(nJob));
if(job == NULL){
perror("nJob malloc faile");
exit(-1);
}
job->job_function = job_fun;
job->user_data = (int*)malloc(sizeof(int));
*(int*)job->user_data = i;
threadPoolQueue(&workerQueue,job);
}
getchar();
return 0;
}
2、异步请求池
当我们向数据库或者DNS服务器发送请求时，需要同步等待他的返回结果，这个过程是比较耗时的，所以衍生出异步发起请求，当发出请求之后，不等待请求的响应，而是通过一个线程去监听，主线程去做其他事情，当请求响应之后如何去做其他事情。
同步向DNS服务器发送请求
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <pthread.h>
#define DNS_SVR "114.114.114.114"
#define DNS_HOST 0x01
#define DNS_CNAME 0x05
struct dns_header {
unsigned short id;
unsigned short flags;
unsigned short qdcount;
unsigned short ancount;
unsigned short nscount;
unsigned short arcount;
};
struct dns_question {
int length;
unsigned short qtype;
unsigned short qclass;
char *qname;
};
struct dns_item {
char *domain;
char *ip;
};
int dns_create_header(struct dns_header *header) {
if (header == NULL) return -1;
memset(header, 0, sizeof(struct dns_header));
srandom(time(NULL));
header->id = random();
header->flags |= htons(0x0100);
header->qdcount = htons(1);
return 0;
}
int dns_create_question(struct dns_question *question, const char *hostname) {
if (question == NULL) return -1;
memset(question, 0, sizeof(struct dns_question));
question->qname = (char*)malloc(strlen(hostname) + 2);
if (question->qname == NULL) return -2;
question->length = strlen(hostname) + 2;
question->qtype = htons(1);
question->qclass = htons(1);
const char delim[2] = ".";
char *hostname_dup = strdup(hostname);
char *token = strtok(hostname_dup, delim);
char *qname_p = question->qname;
while (token != NULL) {
size_t len = strlen(token);
*qname_p = len;
qname_p ++;
strncpy(qname_p, token, len+1);
qname_p += len;
token = strtok(NULL, delim);
}
free(hostname_dup);
return 0;
}
int dns_build_request(struct dns_header *header, struct dns_question *question, char *request) {
int header_s = sizeof(struct dns_header);
int question_s = question->length + sizeof(question->qtype) + sizeof(question->qclass);
int length = question_s + header_s;
int offset = 0;
memcpy(request+offset, header, sizeof(struct dns_header));
offset += sizeof(struct dns_header);
memcpy(request+offset, question->qname, question->length);
offset += question->length;
memcpy(request+offset, &question->qtype, sizeof(question->qtype));
offset += sizeof(question->qtype);
memcpy(request+offset, &question->qclass, sizeof(question->qclass));
return length;
}
static int is_pointer(int in) {
return ((in & 0xC0) == 0xC0);
}
static void dns_parse_name(unsigned char *chunk, unsigned char *ptr, char *out, int *len) {
int flag = 0, n = 0, alen = 0;
char *pos = out + (*len);
while (1) {
flag = (int)ptr[0];
if (flag == 0) break;
if (is_pointer(flag)) {
n = (int)ptr[1];
ptr = chunk + n;
dns_parse_name(chunk, ptr, out, len);
break;
} else {
ptr ++;
memcpy(pos, ptr, flag);
pos += flag;
ptr += flag;
*len += flag;
if ((int)ptr[0] != 0) {
memcpy(pos, ".", 1);
pos += 1;
(*len) += 1;
}
}
}
}
static int dns_parse_response(char *buffer, struct dns_item **domains) {
int i = 0;
unsigned char *ptr = buffer;
ptr += 4;
int querys = ntohs(*(unsigned short*)ptr);
ptr += 2;
int answers = ntohs(*(unsigned short*)ptr);
ptr += 6;
for (i = 0;i < querys;i ++) {
while (1) {
int flag = (int)ptr[0];
ptr += (flag + 1);
if (flag == 0) break;
}
ptr += 4;
}
char cname[128], aname[128], ip[20], netip[4];
int len, type, ttl, datalen;
int cnt = 0;
struct dns_item *list = (struct dns_item*)calloc(answers, sizeof(struct dns_item));
if (list == NULL) {
return -1;
}
for (i = 0;i < answers;i ++) {
bzero(aname, sizeof(aname));
len = 0;
dns_parse_name(buffer, ptr, aname, &len);
ptr += 2;
type = htons(*(unsigned short*)ptr);
ptr += 4;
ttl = htons(*(unsigned short*)ptr);
ptr += 4;
datalen = ntohs(*(unsigned short*)ptr);
ptr += 2;
if (type == DNS_CNAME) {
bzero(cname, sizeof(cname));
len = 0;
dns_parse_name(buffer, ptr, cname, &len);
ptr += datalen;
} else if (type == DNS_HOST) {
bzero(ip, sizeof(ip));
if (datalen == 4) {
memcpy(netip, ptr, datalen);
inet_ntop(AF_INET , netip , ip , sizeof(struct sockaddr));
printf("%s has address %s\n" , aname, ip);
printf("\tTime to live: %d minutes , %d seconds\n", ttl / 60, ttl % 60);
list[cnt].domain = (char *)calloc(strlen(aname) + 1, 1);
memcpy(list[cnt].domain, aname, strlen(aname));
list[cnt].ip = (char *)calloc(strlen(ip) + 1, 1);
memcpy(list[cnt].ip, ip, strlen(ip));
cnt ++;
}
ptr += datalen;
}
}
*domains = list;
ptr += 2;
return cnt;
}
int dns_client_commit(const char *domain) {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
perror("create socket failed\n");
exit(-1);
}
printf("url:%s\n", domain);
struct sockaddr_in dest;
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(53);
dest.sin_addr.s_addr = inet_addr(DNS_SVR);
int ret = connect(sockfd, (struct sockaddr*)&dest, sizeof(dest));
printf("connect :%d\n", ret);
struct dns_header header = {0};
dns_create_header(&header);
struct dns_question question = {0};
dns_create_question(&question, domain);
char request[1024] = {0};
int req_len = dns_build_request(&header, &question, request);
int slen = sendto(sockfd, request, req_len, 0, (struct sockaddr*)&dest, sizeof(struct sockaddr));
char buffer[1024] = {0};
struct sockaddr_in addr;
size_t addr_len = sizeof(struct sockaddr_in);
int n = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&addr, (socklen_t*)&addr_len);
printf("recvfrom n : %d\n", n);
struct dns_item *domains = NULL;
dns_parse_response(buffer, &domains);
return 0;
}
char *domain[] = {
// "www.ntytcp.com",
"bojing.wang",
"www.baidu.com",
"tieba.baidu.com",
"news.baidu.com",
"zhidao.baidu.com",
"music.baidu.com",
"image.baidu.com",
"v.baidu.com",
"map.baidu.com",
"baijiahao.baidu.com",
"xueshu.baidu.com",
"cloud.baidu.com",
"www.163.com",
"open.163.com",
"auto.163.com",
"gov.163.com",
"money.163.com",
"sports.163.com",
"tech.163.com",
"edu.163.com",
"www.taobao.com",
"q.taobao.com",
"sf.taobao.com",
"yun.taobao.com",
"baoxian.taobao.com",
"www.tmall.com",
"suning.tmall.com",
"www.tencent.com",
"www.qq.com",
"www.aliyun.com",
"www.ctrip.com",
"hotels.ctrip.com",
"hotels.ctrip.com",
"vacations.ctrip.com",
"flights.ctrip.com",
"trains.ctrip.com",
"bus.ctrip.com",
"car.ctrip.com",
"piao.ctrip.com",
"tuan.ctrip.com",
"you.ctrip.com",
"g.ctrip.com",
"lipin.ctrip.com",
"ct.ctrip.com"
};
int main(int argc, char *argv[]) {
int count = sizeof(domain) / sizeof(domain[0]);
int i = 0;
for (i = 0;i < count;i ++) {
dns_client_commit(domain[i]);
}
getchar();
}
异步发送请求
1、dns_async_client_init初始化函数
创建epoll、创建线程，用来监控dns的响应消息
2、dns_async_client_commit创建连接，发送请求，将fd加入到epoll中进行监听
3、dns_async_client_proc线程入口函数
通过epoll_wait进行监听，调用取出数据，调用对应的回调函数，epoll_ctl删除节点。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <pthread.h>
#define DNS_SVR "114.114.114.114"
#define DNS_HOST 0x01
#define DNS_CNAME 0x05
#define ASYNC_CLIENT_NUM 1024
struct dns_header {
unsigned short id;
unsigned short flags;
unsigned short qdcount;
unsigned short ancount;
unsigned short nscount;
unsigned short arcount;
};
struct dns_question {
int length;
unsigned short qtype;
unsigned short qclass;
char *qname;
};
struct dns_item {
char *domain;
char *ip;
};
typedef void (*async_result_cb)(struct dns_item *list, int count);
struct async_context {
int epfd;
};
struct ep_arg {
int sockfd;
async_result_cb cb;
};
int dns_create_header(struct dns_header *header) {
if (header == NULL) return -1;
memset(header, 0, sizeof(struct dns_header));
srandom(time(NULL));
header->id = random();
header->flags |= htons(0x0100);
header->qdcount = htons(1);
return 0;
}
int dns_create_question(struct dns_question *question, const char *hostname) {
if (question == NULL) return -1;
memset(question, 0, sizeof(struct dns_question));
question->qname = (char*)malloc(strlen(hostname) + 2);
if (question->qname == NULL) return -2;
question->length = strlen(hostname) + 2;
question->qtype = htons(1);
question->qclass = htons(1);
const char delim[2] = ".";
char *hostname_dup = strdup(hostname);
char *token = strtok(hostname_dup, delim);
char *qname_p = question->qname;
while (token != NULL) {
size_t len = strlen(token);
*qname_p = len;
qname_p ++;
strncpy(qname_p, token, len+1);
qname_p += len;
token = strtok(NULL, delim);
}
free(hostname_dup);
return 0;
}
int dns_build_request(struct dns_header *header, struct dns_question *question, char *request) {
int header_s = sizeof(struct dns_header);
int question_s = question->length + sizeof(question->qtype) + sizeof(question->qclass);
int length = question_s + header_s;
int offset = 0;
memcpy(request+offset, header, sizeof(struct dns_header));
offset += sizeof(struct dns_header);
memcpy(request+offset, question->qname, question->length);
offset += question->length;
memcpy(request+offset, &question->qtype, sizeof(question->qtype));
offset += sizeof(question->qtype);
memcpy(request+offset, &question->qclass, sizeof(question->qclass));
return length;
}
static int is_pointer(int in) {
return ((in & 0xC0) == 0xC0);
}
static int set_block(int fd, int block) {
int flags = fcntl(fd, F_GETFL, 0);
if (flags < 0) return flags;
if (block) {
flags &= ~O_NONBLOCK;
} else {
flags |= O_NONBLOCK;
}
if (fcntl(fd, F_SETFL, flags) < 0) return -1;
return 0;
}
static void dns_parse_name(unsigned char *chunk, unsigned char *ptr, char *out, int *len) {
int flag = 0, n = 0, alen = 0;
char *pos = out + (*len);
while (1) {
flag = (int)ptr[0];
if (flag == 0) break;
if (is_pointer(flag)) {
n = (int)ptr[1];
ptr = chunk + n;
dns_parse_name(chunk, ptr, out, len);
break;
} else {
ptr ++;
memcpy(pos, ptr, flag);
pos += flag;
ptr += flag;
*len += flag;
if ((int)ptr[0] != 0) {
memcpy(pos, ".", 1);
pos += 1;
(*len) += 1;
}
}
}
}
static int dns_parse_response(char *buffer, struct dns_item **domains) {
int i = 0;
unsigned char *ptr = buffer;
ptr += 4;
int querys = ntohs(*(unsigned short*)ptr);
ptr += 2;
int answers = ntohs(*(unsigned short*)ptr);
ptr += 6;
for (i = 0;i < querys;i ++) {
while (1) {
int flag = (int)ptr[0];
ptr += (flag + 1);
if (flag == 0) break;
}
ptr += 4;
}
char cname[128], aname[128], ip[20], netip[4];
int len, type, ttl, datalen;
int cnt = 0;
struct dns_item *list = (struct dns_item*)calloc(answers, sizeof(struct dns_item));
if (list == NULL) {
return -1;
}
for (i = 0;i < answers;i ++) {
bzero(aname, sizeof(aname));
len = 0;
dns_parse_name(buffer, ptr, aname, &len);
ptr += 2;
type = htons(*(unsigned short*)ptr);
ptr += 4;
ttl = htons(*(unsigned short*)ptr);
ptr += 4;
datalen = ntohs(*(unsigned short*)ptr);
ptr += 2;
if (type == DNS_CNAME) {
bzero(cname, sizeof(cname));
len = 0;
dns_parse_name(buffer, ptr, cname, &len);
ptr += datalen;
} else if (type == DNS_HOST) {
bzero(ip, sizeof(ip));
if (datalen == 4) {
memcpy(netip, ptr, datalen);
inet_ntop(AF_INET , netip , ip , sizeof(struct sockaddr));
printf("%s has address %s\n" , aname, ip);
printf("\tTime to live: %d minutes , %d seconds\n", ttl / 60, ttl % 60);
list[cnt].domain = (char *)calloc(strlen(aname) + 1, 1);
memcpy(list[cnt].domain, aname, strlen(aname));
list[cnt].ip = (char *)calloc(strlen(ip) + 1, 1);
memcpy(list[cnt].ip, ip, strlen(ip));
cnt ++;
}
ptr += datalen;
}
}
*domains = list;
ptr += 2;
return cnt;
}
int dns_client_commit(const char *domain) {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
perror("create socket failed\n");
exit(-1);
}
printf("url:%s\n", domain);
set_block(sockfd, 0); //nonblock
struct sockaddr_in dest;
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(53);
dest.sin_addr.s_addr = inet_addr(DNS_SVR);
int ret = connect(sockfd, (struct sockaddr*)&dest, sizeof(dest));
//printf("connect :%d\n", ret);
struct dns_header header = {0};
dns_create_header(&header);
struct dns_question question = {0};
dns_create_question(&question, domain);
char request[1024] = {0};
int req_len = dns_build_request(&header, &question, request);
int slen = sendto(sockfd, request, req_len, 0, (struct sockaddr*)&dest, sizeof(struct sockaddr));
while (1) {
char buffer[1024] = {0};
struct sockaddr_in addr;
size_t addr_len = sizeof(struct sockaddr_in);
int n = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&addr, (socklen_t*)&addr_len);
if (n <= 0) continue;
printf("recvfrom n : %d\n", n);
struct dns_item *domains = NULL;
dns_parse_response(buffer, &domains);
break;
}
return 0;
}
void dns_async_client_free_domains(struct dns_item *list, int count) {
int i = 0;
for (i = 0;i < count;i ++) {
free(list[i].domain);
free(list[i].ip);
}
free(list);
}
//dns_async_client_proc()
//epoll_wait
//result callback
static void* dns_async_client_proc(void *arg) {
struct async_context *ctx = (struct async_context*)arg;
int epfd = ctx->epfd;
while (1) {
struct epoll_event events[ASYNC_CLIENT_NUM] = {0};
int nready = epoll_wait(epfd, events, ASYNC_CLIENT_NUM, -1);
if (nready < 0) {
if (errno == EINTR || errno == EAGAIN) {
continue;
} else {
break;
}
} else if (nready == 0) {
continue;
}
printf("nready:%d\n", nready);
int i = 0;
for (i = 0;i < nready;i ++) {
struct ep_arg *data = (struct ep_arg*)events[i].data.ptr;
int sockfd = data->sockfd;
char buffer[1024] = {0};
struct sockaddr_in addr;
size_t addr_len = sizeof(struct sockaddr_in);
int n = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&addr, (socklen_t*)&addr_len);
struct dns_item *domain_list = NULL;
int count = dns_parse_response(buffer, &domain_list);
data->cb(domain_list, count); //call cb
int ret = epoll_ctl(epfd, EPOLL_CTL_DEL, sockfd, NULL);
//printf("epoll_ctl DEL --> sockfd:%d\n", sockfd);
close(sockfd); /
dns_async_client_free_domains(domain_list, count);
free(data);
}
}
}
//dns_async_client_init()
//epoll init
//thread init
struct async_context *dns_async_client_init(void) {
int epfd = epoll_create(1); //
if (epfd < 0) return NULL;
struct async_context *ctx = calloc(1, sizeof(struct async_context));
if (ctx == NULL) {
close(epfd);
return NULL;
}
ctx->epfd = epfd;
pthread_t thread_id;
int ret = pthread_create(&thread_id, NULL, dns_async_client_proc, ctx);
if (ret) {
perror("pthread_create");
return NULL;
}
usleep(1); //child go first
return ctx;
}
//dns_async_client_commit(ctx, domain)
//socket init
//dns_request
//sendto dns send
int dns_async_client_commit(struct async_context* ctx, const char *domain, async_result_cb cb) {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
perror("create socket failed\n");
exit(-1);
}
printf("url:%s\n", domain);
set_block(sockfd, 0); //nonblock
struct sockaddr_in dest;
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(53);
dest.sin_addr.s_addr = inet_addr(DNS_SVR);
int ret = connect(sockfd, (struct sockaddr*)&dest, sizeof(dest));
//printf("connect :%d\n", ret);
struct dns_header header = {0};
dns_create_header(&header);
struct dns_question question = {0};
dns_create_question(&question, domain);
char request[1024] = {0};
int req_len = dns_build_request(&header, &question, request);
int slen = sendto(sockfd, request, req_len, 0, (struct sockaddr*)&dest, sizeof(struct sockaddr));
struct ep_arg *eparg = (struct ep_arg*)calloc(1, sizeof(struct ep_arg));
if (eparg == NULL) return -1;
eparg->sockfd = sockfd;
eparg->cb = cb;
struct epoll_event ev;
ev.data.ptr = eparg;
ev.events = EPOLLIN;
ret = epoll_ctl(ctx->epfd, EPOLL_CTL_ADD, sockfd, &ev);
//printf(" epoll_ctl ADD: sockfd->%d, ret:%d\n", sockfd, ret);
return ret;
}
char *domain[] = {
"www.ntytcp.com",
"bojing.wang",
"www.baidu.com",
"tieba.baidu.com",
"news.baidu.com",
"zhidao.baidu.com",
"music.baidu.com",
"image.baidu.com",
"v.baidu.com",
"map.baidu.com",
"baijiahao.baidu.com",
"xueshu.baidu.com",
"cloud.baidu.com",
"www.163.com",
"open.163.com",
"auto.163.com",
"gov.163.com",
"money.163.com",
"sports.163.com",
"tech.163.com",
"edu.163.com",
"www.taobao.com",
"q.taobao.com",
"sf.taobao.com",
"yun.taobao.com",
"baoxian.taobao.com",
"www.tmall.com",
"suning.tmall.com",
"www.tencent.com",
"www.qq.com",
"www.aliyun.com",
"www.ctrip.com",
"hotels.ctrip.com",
"hotels.ctrip.com",
"vacations.ctrip.com",
"flights.ctrip.com",
"trains.ctrip.com",
"bus.ctrip.com",
"car.ctrip.com",
"piao.ctrip.com",
"tuan.ctrip.com",
"you.ctrip.com",
"g.ctrip.com",
"lipin.ctrip.com",
"ct.ctrip.com"
};
static void dns_async_client_result_callback(struct dns_item *list, int count) {
int i = 0;
for (i = 0;i < count;i ++) {
printf("name:%s, ip:%s\n", list[i].domain, list[i].ip);
}
}
int main(int argc, char *argv[]) {
#if 0
dns_client_commit(argv[1]);
#else
struct async_context *ctx = dns_async_client_init();
if (ctx == NULL) return -2;
int count = sizeof(domain) / sizeof(domain[0]);
int i = 0;
for (i = 0;i < count;i ++) {
dns_async_client_commit(ctx, domain[i], dns_async_client_result_callback);
//sleep(2);
}
getchar();
#endif
}
3、内存池
内存池主要是解决，频繁开辟和释放内存，造成的内存碎片问题，大量的内存碎片，会导致我们分配内存失败。
内存池是通过，申请比较大的内存块，后面慢慢的去使用他，避免重复申请和释放内存带来的效率消耗和大量内存碎片
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#define MP_ALIGNMENT 32
#define MP_PAGE_SIZE 4096
#define MP_MAX_ALLOC_FROM_POOL (MP_PAGE_SIZE-1)
#define mp_align(n, alignment) (((n)+(alignment-1)) & ~(alignment-1))
#define mp_align_ptr(p, alignment) (void *)((((size_t)p)+(alignment-1)) & ~(alignment-1))
struct mp_large_s {
struct mp_large_s *next;
void *alloc;
};
struct mp_node_s {
unsigned char *last;
unsigned char *end;
struct mp_node_s *next;
size_t failed;
};
struct mp_pool_s {
size_t max;
struct mp_node_s *current;
struct mp_large_s *large;
struct mp_node_s head[0];
};
struct mp_pool_s *mp_create_pool(size_t size);
void mp_destory_pool(struct mp_pool_s *pool);
void *mp_alloc(struct mp_pool_s *pool, size_t size);
void *mp_nalloc(struct mp_pool_s *pool, size_t size);
void *mp_calloc(struct mp_pool_s *pool, size_t size);
void mp_free(struct mp_pool_s *pool, void *p);
struct mp_pool_s *mp_create_pool(size_t size) {
struct mp_pool_s *p;
int ret = posix_memalign((void **)&p, MP_ALIGNMENT, size + sizeof(struct mp_pool_s) + sizeof(struct mp_node_s));
if (ret) {
return NULL;
}
p->max = (size < MP_MAX_ALLOC_FROM_POOL) ? size : MP_MAX_ALLOC_FROM_POOL;
p->current = p->head;
p->large = NULL;
p->head->last = (unsigned char *)p + sizeof(struct mp_pool_s) + sizeof(struct mp_node_s);
p->head->end = p->head->last + size;
p->head->failed = 0;
return p;
}
void mp_destory_pool(struct mp_pool_s *pool) {
struct mp_node_s *h, *n;
struct mp_large_s *l;
for (l = pool->large; l; l = l->next) {
if (l->alloc) {
free(l->alloc);
}
}
h = pool->head->next;
while (h) {
n = h->next;
free(h);
h = n;
}
free(pool);
}
void mp_reset_pool(struct mp_pool_s *pool) {
struct mp_node_s *h;
struct mp_large_s *l;
for (l = pool->large; l; l = l->next) {
if (l->alloc) {
free(l->alloc);
}
}
pool->large = NULL;
for (h = pool->head; h; h = h->next) {
h->last = (unsigned char *)h + sizeof(struct mp_node_s);
}
}
static void *mp_alloc_block(struct mp_pool_s *pool, size_t size) {
unsigned char *m;
struct mp_node_s *h = pool->head;
size_t psize = (size_t)(h->end - (unsigned char *)h);
int ret = posix_memalign((void **)&m, MP_ALIGNMENT, psize);
if (ret) return NULL;
struct mp_node_s *p, *new_node, *current;
new_node = (struct mp_node_s*)m;
new_node->end = m + psize;
new_node->next = NULL;
new_node->failed = 0;
m += sizeof(struct mp_node_s);
m = mp_align_ptr(m, MP_ALIGNMENT);
new_node->last = m + size;
current = pool->current;
for (p = current; p->next; p = p->next) {
if (p->failed++ > 4) {
current = p->next;
}
}
p->next = new_node;
pool->current = current ? current : new_node;
return m;
}
static void *mp_alloc_large(struct mp_pool_s *pool, size_t size) {
void *p = malloc(size);
if (p == NULL) return NULL;
size_t n = 0;
struct mp_large_s *large;
for (large = pool->large; large; large = large->next) {
if (large->alloc == NULL) {
large->alloc = p;
return p;
}
if (n ++ > 3) break;
}
large = mp_alloc(pool, sizeof(struct mp_large_s));
if (large == NULL) {
free(p);
return NULL;
}
large->alloc = p;
large->next = pool->large;
pool->large = large;
return p;
}
void *mp_memalign(struct mp_pool_s *pool, size_t size, size_t alignment) {
void *p;
int ret = posix_memalign(&p, alignment, size);
if (ret) {
return NULL;
}
struct mp_large_s *large = mp_alloc(pool, sizeof(struct mp_large_s));
if (large == NULL) {
free(p);
return NULL;
}
large->alloc = p;
large->next = pool->large;
pool->large = large;
return p;
}
void *mp_alloc(struct mp_pool_s *pool, size_t size) {
unsigned char *m;
struct mp_node_s *p;
if (size <= pool->max) {
p = pool->current;
do {
m = mp_align_ptr(p->last, MP_ALIGNMENT);
if ((size_t)(p->end - m) >= size) {
p->last = m + size;
return m;
}
p = p->next;
} while (p);
return mp_alloc_block(pool, size);
}
return mp_alloc_large(pool, size);
}
void *mp_nalloc(struct mp_pool_s *pool, size_t size) {
unsigned char *m;
struct mp_node_s *p;
if (size <= pool->max) {
p = pool->current;
do {
m = p->last;
if ((size_t)(p->end - m) >= size) {
p->last = m+size;
return m;
}
p = p->next;
} while (p);
return mp_alloc_block(pool, size);
}
return mp_alloc_large(pool, size);
}
void *mp_calloc(struct mp_pool_s *pool, size_t size) {
void *p = mp_alloc(pool, size);
if (p) {
memset(p, 0, size);
}
return p;
}
void mp_free(struct mp_pool_s *pool, void *p) {
struct mp_large_s *l;
for (l = pool->large; l; l = l->next) {
if (p == l->alloc) {
free(l->alloc);
l->alloc = NULL;
return ;
}
}
}
int main(int argc, char *argv[]) {
int size = 1 << 12;
struct mp_pool_s *p = mp_create_pool(size);
int i = 0;
for (i = 0;i < 10;i ++) {
void *mp = mp_alloc(p, 512);
// mp_free(mp);
}
//printf("mp_create_pool: %ld\n", p->max);
printf("mp_align(123, 32): %d, mp_align(17, 32): %d\n", mp_align(24, 32), mp_align(17, 32));
//printf("mp_align_ptr(p->current, 32): %lx, p->current: %lx, mp_align(p->large, 32): %lx, p->large: %lx\n", mp_align_ptr(p->current, 32), p->current, mp_align_ptr(p->large, 32), p->large);
int j = 0;
for (i = 0;i < 5;i ++) {
char *pp = mp_calloc(p, 32);
for (j = 0;j < 32;j ++) {
if (pp[j]) {
printf("calloc wrong\n");
}
printf("calloc success\n");
}
}
//printf("mp_reset_pool\n");
for (i = 0;i < 5;i ++) {
void *l = mp_alloc(p, 8192);
mp_free(p, l);
}
mp_reset_pool(p);
//printf("mp_destory_pool\n");
for (i = 0;i < 58;i ++) {
mp_alloc(p, 256);
}
mp_destory_pool(p);
return 0;
}
