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diff src/event/quic/ngx_event_quic_frames.c @ 8946:56dec0d4e5b1 quic

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QUIC: avoid excessive buffer allocations in stream output. Previously, when a few bytes were send to a QUIC stream by the application, a 4K buffer was allocated for these bytes. Then a STREAM frame was created and that entire buffer was used as data for that frame. The frame with the buffer were in use up until the frame was acked by client. Meanwhile, when more bytes were send to the stream, more buffers were allocated and assigned as data to newer STREAM frames. In this scenario most buffer memory is unused. Now the unused part of the stream output buffer is available for further stream output while earlier parts of the buffer are waiting to be acked. This is achieved by splitting the output buffer.
author Roman Arutyunyan <arut@nginx.com>
date Fri, 24 Dec 2021 18:13:51 +0300
parents a6a328ebd362
children 6ccf3867959a
line wrap: on
line diff
--- a/src/event/quic/ngx_event_quic_frames.c
+++ b/src/event/quic/ngx_event_quic_frames.c
@@ -482,14 +482,14 @@ done:
 
 ngx_int_t
 ngx_quic_order_bufs(ngx_connection_t *c, ngx_chain_t **out, ngx_chain_t *in,
-    size_t offset)
+    off_t limit, off_t offset)
 {
+    off_t         n;
     u_char       *p;
-    size_t        n;
     ngx_buf_t    *b;
     ngx_chain_t  *cl, *sl;
 
-    while (in) {
+    while (in && limit) {
         cl = *out;
 
         if (cl == NULL) {
@@ -523,8 +523,9 @@ ngx_quic_order_bufs(ngx_connection_t *c,
             continue;
         }
 
-        for (p = b->pos + offset; p != b->last && in; /* void */ ) {
+        for (p = b->pos + offset; p != b->last && in && limit; /* void */ ) {
             n = ngx_min(b->last - p, in->buf->last - in->buf->pos);
+            n = ngx_min(n, limit);
 
             if (b->sync) {
                 ngx_memcpy(p, in->buf->pos, n);
@@ -533,6 +534,7 @@ ngx_quic_order_bufs(ngx_connection_t *c,
             p += n;
             in->buf->pos += n;
             offset += n;
+            limit -= n;
 
             if (in->buf->pos == in->buf->last) {
                 in = in->next;