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diff src/os/unix/ngx_freebsd_sendfile_chain.c @ 7985:ec2e6893caaa

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Simplified sendfile(SF_NODISKIO) usage. Starting with FreeBSD 11, there is no need to use AIO operations to preload data into cache for sendfile(SF_NODISKIO) to work. Instead, sendfile() handles non-blocking loading data from disk by itself. It still can, however, return EBUSY if a page is already being loaded (for example, by a different process). If this happens, we now post an event for the next event loop iteration, so sendfile() is retried "after a short period", as manpage recommends. The limit of the number of EBUSY tolerated without any progress is preserved, but now it does not result in an alert, since on an idle system event loop iteration might be very short and EBUSY can happen many times in a row. Instead, SF_NODISKIO is simply disabled for one call once the limit is reached. With this change, sendfile(SF_NODISKIO) is now used automatically as long as sendfile() is enabled, and no longer requires "aio on;".
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 27 Dec 2021 19:48:33 +0300
parents 555533169506
children b002ad258f1d
line wrap: on
line diff
--- a/src/os/unix/ngx_freebsd_sendfile_chain.c
+++ b/src/os/unix/ngx_freebsd_sendfile_chain.c
@@ -32,23 +32,22 @@
 ngx_chain_t *
 ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 {
-    int               rc, flags;
-    off_t             send, prev_send, sent;
-    size_t            file_size;
-    ssize_t           n;
-    ngx_uint_t        eintr, eagain;
-    ngx_err_t         err;
-    ngx_buf_t        *file;
-    ngx_event_t      *wev;
-    ngx_chain_t      *cl;
-    ngx_iovec_t       header, trailer;
-    struct sf_hdtr    hdtr;
-    struct iovec      headers[NGX_IOVS_PREALLOCATE];
-    struct iovec      trailers[NGX_IOVS_PREALLOCATE];
-#if (NGX_HAVE_AIO_SENDFILE)
-    ngx_uint_t        ebusy;
-    ngx_event_aio_t  *aio;
+    int              rc, flags;
+    off_t            send, prev_send, sent;
+    size_t           file_size;
+    ssize_t          n;
+    ngx_err_t        err;
+    ngx_buf_t       *file;
+    ngx_uint_t       eintr, eagain;
+#if (NGX_HAVE_SENDFILE_NODISKIO)
+    ngx_uint_t       ebusy;
 #endif
+    ngx_event_t     *wev;
+    ngx_chain_t     *cl;
+    ngx_iovec_t      header, trailer;
+    struct sf_hdtr   hdtr;
+    struct iovec     headers[NGX_IOVS_PREALLOCATE];
+    struct iovec     trailers[NGX_IOVS_PREALLOCATE];
 
     wev = c->write;
 
@@ -77,11 +76,6 @@ ngx_freebsd_sendfile_chain(ngx_connectio
     eagain = 0;
     flags = 0;
 
-#if (NGX_HAVE_AIO_SENDFILE && NGX_SUPPRESS_WARN)
-    aio = NULL;
-    file = NULL;
-#endif
-
     header.iovs = headers;
     header.nalloc = NGX_IOVS_PREALLOCATE;
 
@@ -90,7 +84,7 @@ ngx_freebsd_sendfile_chain(ngx_connectio
 
     for ( ;; ) {
         eintr = 0;
-#if (NGX_HAVE_AIO_SENDFILE)
+#if (NGX_HAVE_SENDFILE_NODISKIO)
         ebusy = 0;
 #endif
         prev_send = send;
@@ -179,9 +173,8 @@ ngx_freebsd_sendfile_chain(ngx_connectio
 
             sent = 0;
 
-#if (NGX_HAVE_AIO_SENDFILE)
-            aio = file->file->aio;
-            flags = (aio && aio->preload_handler) ? SF_NODISKIO : 0;
+#if (NGX_HAVE_SENDFILE_NODISKIO)
+            flags = (c->busy_count <= 2) ? SF_NODISKIO : 0;
 #endif
 
             rc = sendfile(file->file->fd, c->fd, file->file_pos,
@@ -199,7 +192,7 @@ ngx_freebsd_sendfile_chain(ngx_connectio
                     eintr = 1;
                     break;
 
-#if (NGX_HAVE_AIO_SENDFILE)
+#if (NGX_HAVE_SENDFILE_NODISKIO)
                 case NGX_EBUSY:
                     ebusy = 1;
                     break;
@@ -252,41 +245,30 @@ ngx_freebsd_sendfile_chain(ngx_connectio
 
         in = ngx_chain_update_sent(in, sent);
 
-#if (NGX_HAVE_AIO_SENDFILE)
+#if (NGX_HAVE_SENDFILE_NODISKIO)
 
         if (ebusy) {
             if (sent == 0) {
                 c->busy_count++;
 
-                if (c->busy_count > 2) {
-                    ngx_log_error(NGX_LOG_ALERT, c->log, 0,
-                                  "sendfile(%V) returned busy again",
-                                  &file->file->name);
-
-                    c->busy_count = 0;
-                    aio->preload_handler = NULL;
-
-                    send = prev_send;
-                    continue;
-                }
+                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
+                               "sendfile() busy, count:%d", c->busy_count);
 
             } else {
                 c->busy_count = 0;
             }
 
-            n = aio->preload_handler(file);
-
-            if (n > 0) {
-                send = prev_send + sent;
-                continue;
+            if (wev->posted) {
+                ngx_delete_posted_event(wev);
             }
 
+            ngx_post_event(wev, &ngx_posted_next_events);
+
+            wev->ready = 0;
             return in;
         }
 
-        if (flags == SF_NODISKIO) {
-            c->busy_count = 0;
-        }
+        c->busy_count = 0;
 
 #endif