libevent的evhttp不适合多线程,libevhtp重新设计了libevent的http API,采用了和memcached类似的多线程模型。
worker线程的管道读事件的回调函数为htp__run_in_thread_:
#ifndef EVHTP_DISABLE_EVTHR static void htp__run_in_thread_(evthr_t * thr, void * arg, void * shared) { evhtp_t * htp = shared; evhtp_connection_t * connection = arg; connection->evbase = evthr_get_base(thr); connection->thread = thr; if (htp__connection_accept_(connection->evbase, connection) < 0) { evhtp_connection_free(connection); return; } if (htp__run_post_accept_(htp, connection) < 0) { evhtp_connection_free(connection); return; } } #endif
htp__connection_accept_函数如下:
static int htp__connection_accept_(struct event_base * evbase, evhtp_connection_t * connection) { struct timeval * c_recv_timeo; struct timeval * c_send_timeo; if (htp__run_pre_accept_(connection->htp, connection) < 0) { evutil_closesocket(connection->sock); return -1; } #ifndef EVHTP_DISABLE_SSL if (connection->htp->ssl_ctx != NULL) { connection->ssl = SSL_new(connection->htp->ssl_ctx); connection->bev = bufferevent_openssl_socket_new(evbase, connection->sock, connection->ssl, BUFFEREVENT_SSL_ACCEPTING, connection->htp->bev_flags); SSL_set_app_data(connection->ssl, connection); goto end; } #endif connection->bev = bufferevent_socket_new(evbase, connection->sock, connection->htp->bev_flags); htp_log_debug("enter sock=%d ", connection->sock); #ifndef EVHTP_DISABLE_SSL end: #endif if (connection->recv_timeo.tv_sec || connection->recv_timeo.tv_usec) { c_recv_timeo = &connection->recv_timeo; } else if (connection->htp->recv_timeo.tv_sec || connection->htp->recv_timeo.tv_usec) { c_recv_timeo = &connection->htp->recv_timeo; } else { c_recv_timeo = NULL; } if (connection->send_timeo.tv_sec || connection->send_timeo.tv_usec) { c_send_timeo = &connection->send_timeo; } else if (connection->htp->send_timeo.tv_sec || connection->htp->send_timeo.tv_usec) { c_send_timeo = &connection->htp->send_timeo; } else { c_send_timeo = NULL; } evhtp_connection_set_timeouts(connection, c_recv_timeo, c_send_timeo); connection->resume_ev = event_new(evbase, -1, EV_READ | EV_PERSIST, htp__connection_resumecb_, connection); event_add(connection->resume_ev, NULL); bufferevent_enable(connection->bev, EV_READ); bufferevent_setcb(connection->bev, htp__connection_readcb_, htp__connection_writecb_, htp__connection_eventcb_, connection); return 0; }
此时,conn_fd的读事件已经添加到worker线程的event_base中。
当读事件发生后,最终会运行htp__connection_readcb_,然后调用htparser_run,再调用htp__request_parse_path_:
static int htp__request_parse_path_(htparser * p, const char * data, size_t len) { evhtp_connection_t * c = htparser_get_userdata(p); evhtp_path_t * path; if (htp__require_uri_(c) != 0) { return -1; } if (evhtp_unlikely(!(path = htp__path_new_(data, len)))) { c->request->status = EVHTP_RES_FATAL; return -1; } c->request->uri->path = path; c->request->uri->scheme = htparser_get_scheme(p); c->request->method = htparser_get_method(p); htp__lock_(c->htp); { htp__request_set_callbacks_(c->request); } htp__unlock_(c->htp); if ((c->request->status = htp__hook_path_(c->request, path)) != EVHTP_RES_OK) { return -1; } return 0; }
通过htp__request_set_callbacks_,我们可以设置每个请求的回调函数为evhtp_s结构中的回调函数。
htparser_run后续会调用htp__request_parse_fini_:
static int htp__request_parse_fini_(htparser * p) { evhtp_connection_t * c = htparser_get_userdata(p); if (c->flags & EVHTP_CONN_FLAG_PAUSED) { return -1; } /* check to see if we should use the body of the request as the query * arguments. */ if (htp__should_parse_query_body_(c->request) == 1) { const char * body; size_t body_len; evhtp_uri_t * uri; struct evbuffer * buf_in; uri = c->request->uri; buf_in = c->request->buffer_in; body_len = evbuffer_get_length(buf_in); body = (const char *)evbuffer_pullup(buf_in, body_len); uri->query_raw = calloc(body_len + 1, 1); evhtp_alloc_assert(uri->query_raw); memcpy(uri->query_raw, body, body_len); uri->query = evhtp_parse_query(body, body_len); } /* * XXX c->request should never be NULL, but we have found some path of * execution where this actually happens. We will check for now, but the bug * path needs to be tracked down. * */ if (c->request && c->request->cb) { (c->request->cb)(c->request, c->request->cbarg); } if (c->flags & EVHTP_CONN_FLAG_PAUSED) { return -1; } return 0; }
可以看到,最终request的回调函数被执行。