func[])(dul_node_t **) = {
ws_alloc,
tls_alloc,
uv_alloc,
};
char const *loaders[] = {
"ws", "tls", "uv"
};
dul_node_t *processor_loader(tokenizer_t *tokenizer, const char *loader, dul_node_t *pre_loader) {
char *p = loader;
char *inner_ptr = NULL;
/* params 提取组装 */
p = strtok_r(p, "?", &inner_ptr);
dul_node_t *node = NULL;
map_t params = hashmap_new();
params_parser(inner_ptr, params);
/* 这里采用转移表,进行插件初始化 */
while (strcmp(loaders[sqe], p) != 0) {
sqe++;
}
oper_func[sqe](&node);
if (node == NULL) {
return NULL;
}
node->init(node, params);
hashmap_free(params);
// 双向链表前后关系绑定
pre_loader->next = node;
node->pre = pre_loader;
return node;
}
/* params string 解析 */
void params_parser(char *query, map_t params) {
char *outer_ptr = NULL;
char *p = strtok_r(query, "&", &outer_ptr);
while (p) {
char *inner_ptr = NULL;
char *key = strtok_r(p, "=", &inner_ptr);
hashmap_put(params, key, inner_ptr);
p = strtok_r(NULL, "&", &outer_ptr);
}
}
Tips:随着插件的增加,对应初始化的代码也会越来越多,而且都是重复代码,为了减少这部分工作,我们可以采取宏来定义函数。后续如果增加一个插件,只需要在底下加一行 LOADER_ALLOC(zim_xx, xx)
即可。
#define LOADER_ALLOC(type, name) \
void name##_alloc(dul_node_t **ctx) { \
type##_t **loader = (type##_t **)ctx; \
(*loader) = malloc(sizeof(type##_t)); \
(*loader)->init = &name##_init; \
(*loader)->next = NULL; \
(*loader)->pre = NULL; \
}
LOADER_ALLOC(websocket, ws);
LOADER_ALLOC(zim_tls, tls);
LOADER_ALLOC(zim_uv, uv);
接口调用
再回到一开始我们思考接口调用的问题,由于有了函数指针变量,我们就需要在插件的初始化中把函数的地址存储在这些变量中:
int ws_init(dul_node_t *ctx, map_t params) {
websocket_t *ws = (websocket_t *)ctx;
bzero(ws, sizeof(websocket_t));
// 省略中间初始化过程
ws->init = &ws_init;
ws->conn = &ws_connect;
ws->close = &ws_close;
ws->destroy = &ws_destroy;
ws->reset = &ws_reset;
ws->write_data = &ws_send;
ws->read_data = &ws_read;
ws->conn_cb = &ws_conn_cb;
ws->write_cb = &ws_send_cb;
ws->recv_cb = &ws_recv_cb;
ws->close_cb = &ws_close_cb;
return OK;
}
对比接口前后调用的方式,前者需要知道下一个 connect 函数,并进行显式调用,如果在 TLS 和 TCP 中新增一层,就需要改动 connect 函数的调用。但后者完全没有这个顾虑,不论是新增还是删除插件,它都可以通过指针找到对应的结构体,调用其 connect 函数,插件内部无需任何改动,岂不妙哉。
/* 改造前 */
int tls_ws_connect(tls_ws_t *handle,
tls_ws_conn_cb conn_cb,
tls_ws_close_cb close_cb) {
...
return uv_tls_connect(tls,
handle->host,
handle->port,
on__tls_connect);
}
/* 改造后 */
static void tls_connect(dul_node_t *ctx) {
zim_tls_t *tls = (zim_tls_t *)ctx;
...
if (tls->next && tls->next->conn) {
tls->next->host = tls->host;
tls->next->port = tls->port;
tls->next->conn(tls->next);
}
}
新增插件
基于改造后组件,新增插件只需要改动三处,以日志插件为例:
在头文件中定义 zim_log_s
结构体(这里没有额外的成员):
typedef struct zim_log_s zim_log_t;
struct zim_log_s {
dul_node_t *pre;
dul_node_t *next;
char *host;
int port;
map_t params;
node_init init;
node_conn conn;
node_write_data write_data;
node_read_data read_data;
node_close close;
node_destroy destroy;
node_reset reset;
node_conn_cb conn_cb;
node_write_cb write_cb