int main(int argc, char **argv)
{// 版本信息cout << event_get_version() << endl;// 所支持的IO复用方法const char **methods = event_get_supported_methods();for (int i = 0; methods[i] != NULL; i++) {cout << methods[i] << endl;}return 0;
}

void log(const char *fmt, ...)
{char buff[512];va_list ap;va_start(ap, fmt);int len = vsnprintf(buff, sizeof(buff), fmt, ap);buff[len] = '\0';va_end(ap);cout << buff << endl;
}

log("hi, are you %s?", "luxon28");
log("name=%s, age=%d", "luoxn28", 23);

#include <iostream>#include <event.h>
#include <event2/http.h>using namespace std;// Time callback function
void onTime(int sock, short event, void *arg)
{static int cnt = 0;cout << "Game Over! " << cnt++ << endl;struct timeval tv;tv.tv_sec = 1;tv.tv_usec = 0;if (cnt < 5) {// Add timer eventevent_add((struct event *) arg, &tv);}else {cout << "onTime is over" << endl;}
}int main(int argc, char **argv)
{cout << event_get_version() << endl;struct event_base *base = event_init();struct event ev;evtimer_set(&ev, onTime, &ev);struct timeval timeevent;timeevent.tv_sec = 1;timeevent.tv_usec = 0;event_add(&ev, &timeevent);// Start event loopevent_base_dispatch(base);event_base_free(base);return 0;
}

/* 结构体event_base是Libevent的Reactor */
struct event_base {/* 初始化Reactor时选择的一种后端IO复用机制，并记录在如下字段中 */const struct eventop *evsel;/* 指向IO复用机制真正存储的数据，它通过evsel成员的init函数来进行初始化 */void *evbase;/* 事件变化队列，其用途是:如果一个文件描述符上注册的事件被多次修改，则可以使用缓冲区来避免重复的* 系统调用(比如epoll_wait)。它仅能用于时间复杂度为O(1)的IO复用技术 */struct event_changelist changelist;/* 指向信号的后端处理机制，目前仅在singal.h文件中定义了一种处理方法 */const struct eventop *evsigsel;/* 信号事件处理器使用的数据结构，其中封装了一个由socketpair创建的管道。它用于信号处理函数和* 事件多路分发器之间的通信 */struct evsig_info sig;/* 以下3个成员是添加到该event_base的虚拟事件、所有事件和激活事件的数量 */int virtual_event_count;int event_count;int event_count_active;/* 是否执行完活动事件队列上的剩余的任务之后就退出事件处理 */int event_gotterm;/* 是否立即退出事件循环，而不管是否还有任务需要处理 */int event_break;/* 是否应该启动一个新的事件循环 */int event_continue;/* 目前正在处理的活动事件队列的优先级 */int event_running_priority;/* 事件循环是否启动 */int running_loop;/* 活动事件队列数组，索引值越小的队列，优先级越高。高优先级的活动事件队列中的事件处理器将被优先处理 */struct event_list *activequeues;/* 活动事件队列数组的大小，即该event_base共有nactivequeues个不同优先级的活动事件队列 */int nactivequeues;/* common timeout logic *//* 以下3个成员用于管理通用定时器队列 */struct common_timeout_list **common_timeout_queues;int n_common_timeouts;int n_common_timeouts_allocated;/* 存放延时回调函数的链表，事件循环每次成功处理完一个活动事件队列中的所有事件之后，* 就调用一次延迟回调函数 */struct deferred_cb_queue defer_queue;/* 文件描述符和IO事件之间的映射关系表 */struct event_io_map io;/* 信号值和信号事件之间的映射关系表 */struct event_signal_map sigmap;/* 注册事件队列，存放IO事件处理器和信号事件处理器 */struct event_list eventqueue;struct timeval event_tv;/* 时间堆 */struct min_heap timeheap;struct timeval tv_cache;#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)/** Difference between internal time (maybe from clock_gettime) and* gettimeofday. */struct timeval tv_clock_diff;/** Second in which we last updated tv_clock_diff, in monotonic time. */time_t last_updated_clock_diff;
#endif/* 多线程支持 */
#ifndef _EVENT_DISABLE_THREAD_SUPPORT/* threading support *//** The thread currently running the event_loop for this base *//* 当前运行该event_base的事件循环的线程 */unsigned long th_owner_id;/** A lock to prevent conflicting accesses to this event_base */void *th_base_lock;            /* 锁变量 *//** The event whose callback is executing right now *//* 当前事件循环正在执行哪个事件处理器的回调函数 */struct event *current_event;/** A condition that gets signalled when we're done processing an* event with waiters on it. *//* 条件变量，用于唤醒正在等待某个事件处理完毕的线程 */void *current_event_cond;/** Number of threads blocking on current_event_cond. */int current_event_waiters;    /* 等待current_event_cond的线程数 */
#endif/** Flags that this base was configured with *//* 该vent_base的一些配置参数 */enum event_base_config_flag flags;/* 下面这些成员变量给工作线程唤醒主线程提供了方法(使用socketpair创建的管道) *//* Notify main thread to wake up break, etc. *//** True if the base already has a pending notify, and we don't need* to add any more. */int is_notify_pending;/** A socketpair used by some th_notify functions to wake up the main* thread. */evutil_socket_t th_notify_fd[2];/** An event used by some th_notify functions to wake up the main* thread. */struct event th_notify;/** A function used to wake up the main thread from another thread. */int (*th_notify_fn)(struct event_base *base);
}

#include <iostream>#include <event2/event.h>
#include <event2/buffer.h>
#include <event2/http.h>using namespace std;#define INFO 1
#define ERR  3
static void log(int level, string info)
{switch (level) {case INFO:cout << "[info] tid[" << pthread_self() << "]: " << info << endl;break;case ERR:cout << "[err] tid[" << pthread_self() << "]: " << info << endl;break;default:break;}
}/*** http callback function*/
void httpHandler(struct evhttp_request *request, void *arg) {struct evbuffer *buff = evbuffer_new();if (!buff) {log(INFO, "evbuffer_new error");return;}evbuffer_add_printf(buff, "Hello world</br>");evbuffer_add_printf(buff, "Server Responsed.</br> Requested: %s<br/>", evhttp_request_get_uri(request));evbuffer_add_printf(buff, " Host: %s<br/>", evhttp_request_get_host(request));evbuffer_add_printf(buff, " Command: %d", evhttp_request_get_command(request));evhttp_send_reply(request, HTTP_OK, "OK", buff);evbuffer_free(buff);
}int main(int argc, char **argv)
{struct event_base *base = event_base_new();struct evhttp *httpServer = evhttp_new(base);int result = evhttp_bind_socket(httpServer, NULL, 8080);if (result != 0) {log(ERR, "evhttp_bind_socket error");return -1;}/* 这是http回调函数 */evhttp_set_gencb(httpServer, httpHandler, NULL);cout << "Http server start OK..." << endl;event_base_dispatch(base);evhttp_free(httpServer);event_base_free(base);return 0;
}