Accept moderation in case of EMFILE/ENFILE.

In case of EMFILE/ENFILE returned from accept() we disable accept events,
and (in case of no accept mutex used) arm timer to re-enable them later.
With accept mutex we just drop it, and rely on normal accept mutex handling
to re-enable accept events once it's acquired again.

As we now handle errors in question, logging level was changed to "crit"
(instead of "alert" used for unknown errors).

Note: the code might call ngx_enable_accept_events() multiple times if
there are many listen sockets.  The ngx_enable_accept_events() function was
modified to check if connection is already active (via c->read->active) and
skip it then, thus making multiple calls safe.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/os/unix/ngx_errno.h b/src/os/unix/ngx_errno.h
index 78af40bfe..2912dea04 100644
--- a/src/os/unix/ngx_errno.h
+++ b/src/os/unix/ngx_errno.h
@@ -29,6 +29,8 @@ typedef int               ngx_err_t;
 #define NGX_ENOTDIR       ENOTDIR
 #define NGX_EISDIR        EISDIR
 #define NGX_EINVAL        EINVAL
+#define NGX_ENFILE        ENFILE
+#define NGX_EMFILE        EMFILE
 #define NGX_ENOSPC        ENOSPC
 #define NGX_EPIPE         EPIPE
 #define NGX_EINPROGRESS   EINPROGRESS