struct event_base { const struct eventop *evsel; //lievent支持select epoll kequeue..等網絡api,包括init、add、del、dispatch的接口,每種網絡框架都支持 void *evbase; //支持相應網絡api的 結構對象，必須epoll就是epoll_create返回epfd相干的內容, //由于每種網絡接口都不1樣，所以需要使用void* int event_count; //總網絡事件數 int event_count_active; //激活事件數 int event_gotterm; //event_base_dispatch中終止while循環 int event_break; //event_base_dispatch終止while立刻 struct event_list **activequeues;//用于保存激活事件列表，是1個2維數組,第1維用于權限number，越低越高，第2維為激活列表 int nactivequeues; // 激活權限列表有多少個權限 struct evsignal_info sig; //保存著信號相干的內容 struct event_list eventqueue; //保存著注冊的事件列表 struct timeval event_tv; //用于和tv_cache肯定是不是時間被修改了，如果使用monotonic時間是不被修改的，gettimeofday才會用到 struct min_heap timeheap; //用于時間堆（最小堆）管理 struct timeval tv_cache; };

struct event_base * event_init(void) { struct event_base *base = event_base_new(); if (base != NULL) current_base = base;//如果創建成功那末就會把current_base更新為新創建的base return (base); }

struct event_base * event_base_new(void) { int i; struct event_base *base; //先創建1個even_base對象 if ((base = calloc(1, sizeof(struct event_base))) == NULL) event_err(1, "%s: calloc", __func__); event_sigcb = NULL; event_gotsig = 0; //檢測系統是不是可使用MONOTONIC time detect_monotonic(); //填充base->event_tv記錄創建base的時間 gettime(base, &base->event_tv); //初始化最小定時器堆，p n a都置為0 min_heap_ctor(&base->timeheap); //初始化隊列first = NULL and last = &first TAILQ_INIT(&base->eventqueue); //初始化用于信號通訊的socket,使用的是sockpair unix網絡套接字 base->sig.ev_signal_pair[0] = ⑴; base->sig.ev_signal_pair[1] = ⑴; base->evbase = NULL; for (i = 0; eventops[i] && !base->evbase; i++) { //event會優先選擇epoll，這個數組是依照索引優先權降落 base->evsel = eventops[i]; base->evbase = base->evsel->init(base); } if (base->evbase == NULL) event_errx(1, "%s: no event mechanism available", __func__); if (getenv("EVENT_SHOW_METHOD")) event_msgx("libevent using: %s ", base->evsel->name); /* allocate a single active event queue */ event_base_priority_init(base, 1); return (base); }

int event_base_priority_init(struct event_base *base, int npriorities) { int i; if (base->event_count_active) return (⑴); //先釋放 if (base->nactivequeues && npriorities != base->nactivequeues) { for (i = 0; i < base->nactivequeues; ++i) { free(base->activequeues[i]); } free(base->activequeues); } /* Allocate our priority queues */ //先分配1維權限數組 base->nactivequeues = npriorities; base->activequeues = (struct event_list **)calloc(base->nactivequeues, npriorities * sizeof(struct event_list *)); if (base->activequeues == NULL) event_err(1, "%s: calloc", __func__); //再初始化2維激活事件列表 for (i = 0; i < base->nactivequeues; ++i) { base->activequeues[i] = malloc(sizeof(struct event_list)); if (base->activequeues[i] == NULL) event_err(1, "%s: malloc", __func__); TAILQ_INIT(base->activequeues[i]); } return (0); }