OPTIM: http: optimize the response forward state machine

By replacing the if/else series with a switch/case, we could save
another 20% on the worst case (chunks of 1 byte).

diff --git a/src/proto_http.c b/src/proto_http.c
index 7abfe31d35ada134dfab64e455e5cfc7008e7657..087cd4703404e313bd9ba3be73fff170f41e5a03 100644 (file)
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -5784,6 +5784,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
        static struct buffer *tmpbuf = NULL;
        int compressing = 0;
        int consumed_data = 0;
+       int ret;
 
        if (unlikely(msg->msg_state < HTTP_MSG_BODY))
                return 0;
@@ -5824,7 +5825,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
        }
 
        if (s->comp_algo != NULL) {
-               int ret = http_compression_buffer_init(s, res->buf, tmpbuf); /* init a buffer with headers */
+               ret = http_compression_buffer_init(s, res->buf, tmpbuf); /* init a buffer with headers */
                if (ret < 0)
                        goto missing_data; /* not enough spaces in buffers */
                compressing = 1;
@@ -5843,10 +5844,8 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
                        }
                }
 
-               if (msg->msg_state == HTTP_MSG_DATA) {
-                       int ret;
-
-                       /* must still forward */
+               switch (msg->msg_state - HTTP_MSG_DATA) {
+               case HTTP_MSG_DATA - HTTP_MSG_DATA:     /* must still forward */
                        if (compressing) {
                                consumed_data += ret = http_compression_buffer_add_data(s, res->buf, tmpbuf);
                                if (ret < 0)
@@ -5865,15 +5864,37 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
                                        http_compression_buffer_end(s, &res->buf, &tmpbuf, 1);
                                        compressing = 0;
                                }
+                               break;
                        }
-               }
-               else if (msg->msg_state == HTTP_MSG_CHUNK_SIZE) {
+                       /* fall through for HTTP_MSG_CHUNK_CRLF */
+
+               case HTTP_MSG_CHUNK_CRLF - HTTP_MSG_DATA:
+                       /* we want the CRLF after the data */
+
+                       ret = http_skip_chunk_crlf(msg);
+                       if (ret == 0)
+                               goto missing_data;
+                       else if (ret < 0) {
+                               if (msg->err_pos >= 0)
+                                       http_capture_bad_message(&s->be->invalid_rep, s, msg, HTTP_MSG_CHUNK_CRLF, s->fe);
+                               goto return_bad_res;
+                       }
+                       /* skipping data in buffer for compression */
+                       if (compressing) {
+                               b_adv(res->buf, msg->next);
+                               msg->next = 0;
+                               msg->sov = 0;
+                               msg->sol = 0;
+                       }
+                       /* we're in MSG_CHUNK_SIZE now, fall through */
+
+               case HTTP_MSG_CHUNK_SIZE - HTTP_MSG_DATA:
                        /* read the chunk size and assign it to ->chunk_len, then
                         * set ->sov and ->next to point to the body and switch to DATA or
                         * TRAILERS state.
                         */
-                       int ret = http_parse_chunk_size(msg);
 
+                       ret = http_parse_chunk_size(msg);
                        if (ret == 0)
                                goto missing_data;
                        else if (ret < 0) {
@@ -5896,30 +5917,10 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
                                }
                        }
                        /* otherwise we're in HTTP_MSG_DATA or HTTP_MSG_TRAILERS state */
-               }
-               else if (msg->msg_state == HTTP_MSG_CHUNK_CRLF) {
-                       /* we want the CRLF after the data */
-                       int ret = http_skip_chunk_crlf(msg);
-
-                       if (ret == 0)
-                               goto missing_data;
-                       else if (ret < 0) {
-                               if (msg->err_pos >= 0)
-                                       http_capture_bad_message(&s->be->invalid_rep, s, msg, HTTP_MSG_CHUNK_CRLF, s->fe);
-                               goto return_bad_res;
-                       }
-                       /* skipping data in buffer for compression */
-                       if (compressing) {
-                               b_adv(res->buf, msg->next);
-                               msg->next = 0;
-                               msg->sov = 0;
-                               msg->sol = 0;
-                       }
-                       /* we're in MSG_CHUNK_SIZE now */
-               }
-               else if (msg->msg_state == HTTP_MSG_TRAILERS) {
-                       int ret = http_forward_trailers(msg);
+                       break;
 
+               case HTTP_MSG_TRAILERS - HTTP_MSG_DATA:
+                       ret = http_forward_trailers(msg);
                        if (ret == 0)
                                goto missing_data;
                        else if (ret < 0) {
@@ -5932,11 +5933,12 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
                                channel_forward(res, msg->next);
                                msg->next = 0;
                        }
-                       /* we're in HTTP_MSG_DONE now */
-               }
-               else {
-                       int old_state = msg->msg_state;
+                       /* we're in HTTP_MSG_DONE now, fall through */
+
+               default:
                        /* other states, DONE...TUNNEL */
+
+                       ret = msg->msg_state;
                        /* for keep-alive we don't want to forward closes on DONE */
                        if ((txn->flags & TX_CON_WANT_MSK) == TX_CON_WANT_KAL ||
                            (txn->flags & TX_CON_WANT_MSK) == TX_CON_WANT_SCL)
@@ -5954,7 +5956,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
                                                goto aborted_xfer;
                                        }
                                        if (msg->err_pos >= 0)
-                                               http_capture_bad_message(&s->be->invalid_rep, s, msg, old_state, s->fe);
+                                               http_capture_bad_message(&s->be->invalid_rep, s, msg, ret, s->fe);
                                        goto return_bad_res;
                                }
                                return 1;