多线程中使用libevent

涉及到的API：

1) evthread_use_pthreads()

2)

struct bufferevent *bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE | BEV_OPT_THREADSAFE);

void bufferevent_lock(struct bufferevent *bufev);
void bufferevent_unlock(struct bufferevent *bufev);

Locking the bufferevent with this function will lock its associated evbuffersas well.

3)

evbuffer_enable_locking(bev->output,null)

evbuffer_enable_locking(bev->input,null)

void evbuffer_lock(struct evbuffer *buf);
void evbuffer_unlock(struct evbuffer *buf);

/* epthreads.c */
#include <stdlib.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/thread.h>
#include <event2/util.h>
#include <pthread.h>

int main(int argc, const char *argv[])
{
struct event_base *base = event_base_new();
int options = BEV_OPT_CLOSE_ON_FREE | BEV_OPT_THREADSAFE ;
struct bufferevent *bev = bufferevent_socket_new(base, -1, options);
if (bev == NULL) abort();

bufferevent_free(bev);
event_base_free(base);

return 0;
}

CFLAGS=-Wall -O0 -g -ggdb -I/usr/include
LDFLAGS=-L/usr/lib -levent_core -levent_extra -lpthread -levent_pthreads

all: epthreads

epthreads: epthreads.c
gcc $(CFLAGS) $(LDFLAGS) epthreads.c -o epthreads

clean:
rm -f *.o *~ epthreads

/*
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"
#endif

static 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 *);

int
main(int argc, char **argv)
{
int i = 0;
struct event_base *base;
struct evconnlistener *listener;
struct event *signal_event;

struct sockaddr_in sin;
#ifdef WIN32
WSADATA wsa_data;
WSAStartup(0x0201, &wsa_data);
#endif

base = 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 void
listener_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 void
conn_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 lock
int 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 void
conn_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 void
conn_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 void
signal_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 threads.c -o thread -levent_core -lpthread -levent_pthreads