Libevent群：很值得体会的多线程编程

/*  This exmple program provides a trivial server program that listens for TCP  connections on port 9995.  When they arrive, it writes a short message to  each client connection, and closes each connection once it is flushed.  Where possible, it exits cleanly in response to a SIGINT (ctrl-c).*/#include <string.h>#include <errno.h>#include <stdio.h>#include <signal.h>#ifndef WIN32#include <netinet/in.h># ifdef _XOPEN_SOURCE_EXTENDED#  include <arpa/inet.h># endif#include <sys/socket.h>#endif#include <event2/bufferevent.h>#include <event2/buffer.h>#include <event2/listener.h>#include <event2/util.h>#include <event2/event.h>#include <event2/bufferevent.h>#include <event2/thread.h>#include <pthread.h>#ifndef USE_X_PRINT#define aPrt printf#define dPrt printf#define ePrt printf#define bgPrt printf#define edPrt printf#else #include "hx_debug.h"#endifstatic int flag = 0;static const char MESSAGE[] = "Hello, World!\n";static const int PORT = 9995;static void listener_cb(struct evconnlistener *, evutil_socket_t,    struct sockaddr *, int socklen, void *);static void conn_writecb(struct bufferevent *, void *);static void conn_readcb(struct bufferevent *, void *);static void conn_eventcb(struct bufferevent *, short, void *);static void signal_cb(evutil_socket_t, short, void *);intmain(int argc, char **argv){int i = 0;struct event_base *base;struct evconnlistener *listener;struct event *signal_event;struct sockaddr_in sin;#ifdef WIN32WSADATA wsa_data;WSAStartup(0x0201, &wsa_data);#endifbase = event_base_new();if (!base) {fprintf(stderr, "Could not initialize libevent!\n");return 1;}/* 支持线程 */evthread_use_pthreads();memset(&sin, 0, sizeof(sin));sin.sin_family = AF_INET;sin.sin_port = htons(PORT);/* LEV_OPT_THREADSAFE 支持 listener 多线程 */listener = evconnlistener_new_bind(base, listener_cb, (void *)base,    LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE|LEV_OPT_THREADSAFE, -1,    (struct sockaddr*)&sin,    sizeof(sin));if (!listener) {fprintf(stderr, "Could not create a listener!\n");return 1;}/* 信号 */signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);if (!signal_event || event_add(signal_event, NULL)<0) {fprintf(stderr, "Could not create/add a signal event!\n");return 1;}// 打印event正在使用的方法char **a = event_get_supported_methods();for( i=0; a[i]!=NULL; i++ ) {printf( "[%s]\n", a[i] );}event_base_dispatch(base);evconnlistener_free(listener);event_free(signal_event);event_base_free(base);printf("done\n");return 0;}static voidlistener_cb(struct evconnlistener *listener, evutil_socket_t fd,    struct sockaddr *sa, int socklen, void *user_data){struct event_base *base = user_data;struct bufferevent *bev;printf( "begin listener_cb \n" );/* sleep(3); */bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE | BEV_OPT_THREADSAFE );/* bev = bufferevent_socket_new(base, fd,BEV_OPT_THREADSAFE ); */if (!bev) {fprintf(stderr, "Error constructing bufferevent!");event_base_loopbreak(base);return;}// 设置超时时间 // 客户端连接上服务器，服务端在规定是否没有读到则调用conn_eventcb进行超时处理struct timeval tv_read = { 10, 0 }, tv_write = { 10, 0 };bufferevent_set_timeouts (bev, &tv_read, &tv_write);/* BEV_OPT_THREADSAFE-支持 buffevent 多线程 */int ret = bufferevent_enable(bev, BEV_OPT_THREADSAFE );if( ret < 0 ) { printf( "----------------------------\n" ); } printf( "bev addr [%x]\n", (int)bev );/* bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL); */// 在回调函数中使用user_data共享通信 什么情况释放, 由谁释放? 在bufferevent_free后释放char *userData = NULL;bufferevent_setcb(bev, conn_readcb, conn_writecb, conn_eventcb, userData );// 延迟设置 写调用//bufferevent_enable(bev, EV_WRITE);bufferevent_disable(bev, EV_WRITE);bufferevent_enable(bev, EV_READ);//bufferevent_disable(bev, EV_READ);/*printf( "will call bufferevent_write\n" );bufferevent_write(bev, MESSAGE, strlen(MESSAGE));printf( "end listener_cb \n" );*/}void * testThreadFun(void * bev ){bufferevent_lock(bev);printf( "10 s sleep  at testThreadFun\n" );sleep(10);printf( "up at testThreadFun\n" );bufferevent_unlock(bev);}/* * bufferevent_read 不带结束符 * data[len]='\0'; * */static voidconn_readcb(struct bufferevent *bev, void *user_data){printf( "begin conn_readcb\n" );printf( "bev addr [%x]\n", (int)bev );struct evbuffer *input = bufferevent_get_input(bev);pthread_t testThread, testThread2;//test lockint ret = pthread_create(&testThread, NULL, testThreadFun, bev);if( -1 == ret ) { printf( "create thread error\n" ); } ret = pthread_create(&testThread2, NULL, testThreadFun, bev);if( -1 == ret ) { printf( "create thread error\n" ); } char data[100];int len = 0;dPrt( "input len [%d]\n", evbuffer_get_length(input) ) ;len = bufferevent_read(bev, data, sizeof(data)-1 ); //data[len]='\0';dPrt( "data[%d][%d][%s]\n", len,strlen(data), data );dPrt( "input len [%d]\n", evbuffer_get_length(input) ) ;/* struct evbuffer *input = bufferevent_get_input(bev);if (evbuffer_get_length(input) == 0) {printf("flushed answer\n");bufferevent_free(bev);}*/bufferevent_enable(bev, EV_WRITE);printf( "will call bufferevent_write\n" );bufferevent_write(bev, MESSAGE, strlen(MESSAGE));//flag = 1;bufferevent_write(bev, MESSAGE, strlen(MESSAGE));printf( "end listener_cb \n" );printf( "end conn_readcb\n" );}static voidconn_writecb(struct bufferevent *bev, void *user_data){printf( "begin conn_writecb \n" );printf( "bev addr [%x]\n", (int)bev );int len = 0;/*  关闭客户的连接*/struct evbuffer *output = bufferevent_get_output(bev);len = evbuffer_get_length(output);printf( "len[%d]\n", len );if ( 0 == len && flag /* evbuffer_get_length(output) == 0 && flag*/ ) {printf("flushed answer\n");bufferevent_free(bev);}printf( "end conn_writecb \n" );}static voidconn_eventcb(struct bufferevent *bev, short events, void *user_data){printf( "begin conn_eventcb\n" );if (events & BEV_EVENT_EOF) {printf("Connection closed.\n");} else if (events & BEV_EVENT_ERROR) {printf("Got an error on the connection: %s\n",    strerror(errno));/*XXX win32*/}/* None of the other events can happen here, since we haven't enabled * timeouts */bufferevent_free(bev);printf( "end conn_eventcb\n" );}static voidsignal_cb(evutil_socket_t sig, short events, void *user_data){struct event_base *base = user_data;struct timeval delay = { 2, 0 };printf("Caught an interrupt signal; exiting cleanly in two seconds.\n");event_base_loopexit(base, &delay);}

gcc hello_world.c -g -o myhello_world -levent_pthreads

/usr/bin/ld: /tmp/ccQLQu5h.o: undefined reference to symbol 'pthread_create@@GLIBC_2.2.5'
/lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

编译出现问题，你知道怎么改正吗？