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;".

1 files changed, 0 insertions, 82 deletions

diff --git a/src/http/ngx_http_copy_filter_module.c b/src/http/ngx_http_copy_filter_module.c
index b47e4afa7..bd3028bc7 100644
--- a/src/http/ngx_http_copy_filter_module.c
+++ b/src/http/ngx_http_copy_filter_module.c
@@ -19,10 +19,6 @@ typedef struct {
 static void ngx_http_copy_aio_handler(ngx_output_chain_ctx_t *ctx,
     ngx_file_t *file);
 static void ngx_http_copy_aio_event_handler(ngx_event_t *ev);
-#if (NGX_HAVE_AIO_SENDFILE)
-static ssize_t ngx_http_copy_aio_sendfile_preload(ngx_buf_t *file);
-static void ngx_http_copy_aio_sendfile_event_handler(ngx_event_t *ev);
-#endif
 #endif
 #if (NGX_THREADS)
 static ngx_int_t ngx_http_copy_thread_handler(ngx_thread_task_t *task,
@@ -128,9 +124,6 @@ ngx_http_copy_filter(ngx_http_request_t *r, ngx_chain_t *in)
 #if (NGX_HAVE_FILE_AIO)
         if (ngx_file_aio && clcf->aio == NGX_HTTP_AIO_ON) {
             ctx->aio_handler = ngx_http_copy_aio_handler;
-#if (NGX_HAVE_AIO_SENDFILE)
-            ctx->aio_preload = ngx_http_copy_aio_sendfile_preload;
-#endif
         }
 #endif
 
@@ -207,81 +200,6 @@ ngx_http_copy_aio_event_handler(ngx_event_t *ev)
     ngx_http_run_posted_requests(c);
 }
 
-
-#if (NGX_HAVE_AIO_SENDFILE)
-
-static ssize_t
-ngx_http_copy_aio_sendfile_preload(ngx_buf_t *file)
-{
-    ssize_t                  n;
-    static u_char            buf[1];
-    ngx_event_aio_t         *aio;
-    ngx_http_request_t      *r;
-    ngx_output_chain_ctx_t  *ctx;
-
-    aio = file->file->aio;
-    r = aio->data;
-
-    if (r->aio) {
-        /*
-         * tolerate sendfile() calls if another operation is already
-         * running; this can happen due to subrequests, multiple calls
-         * of the next body filter from a filter, or in HTTP/2 due to
-         * a write event on the main connection
-         */
-
-        return NGX_AGAIN;
-    }
-
-    n = ngx_file_aio_read(file->file, buf, 1, file->file_pos, NULL);
-
-    if (n == NGX_AGAIN) {
-        aio->handler = ngx_http_copy_aio_sendfile_event_handler;
-
-        r->main->blocked++;
-        r->aio = 1;
-
-        ctx = ngx_http_get_module_ctx(r, ngx_http_copy_filter_module);
-        ctx->aio = 1;
-    }
-
-    return n;
-}
-
-
-static void
-ngx_http_copy_aio_sendfile_event_handler(ngx_event_t *ev)
-{
-    ngx_event_aio_t     *aio;
-    ngx_connection_t    *c;
-    ngx_http_request_t  *r;
-
-    aio = ev->data;
-    r = aio->data;
-    c = r->connection;
-
-    r->main->blocked--;
-    r->aio = 0;
-    ev->complete = 0;
-
-#if (NGX_HTTP_V2)
-
-    if (r->stream) {
-        /*
-         * for HTTP/2, update write event to make sure processing will
-         * reach the main connection to handle sendfile() preload
-         */
-
-        c->write->ready = 1;
-        c->write->active = 0;
-    }
-
-#endif
-
-    c->write->handler(c->write);
-}
-
-#endif
 #endif