[nginx] Syslog: enabled logging of send errors.

[Homutov Vladimir]

details:   http://hg.nginx.org/nginx/rev/2cb5275bf5e7
branches:  
changeset: 5857:2cb5275bf5e7
user:      Vladimir Homutov <vl at nginx.com>
date:      Mon Sep 01 17:55:07 2014 +0400
description:
Syslog: enabled logging of send errors.

The ngx_cycle->log is used when sending the message.  This allows to log syslog
send errors in another log.

Logging to syslog after its cleanup handler has been executed was prohibited.
Previously, this was possible from ngx_destroy_pool(), which resulted in error
messages caused by attempts to write into the closed socket.

The "processing" flag is renamed to "busy" to better match its semantics.

diffstat:

 src/core/ngx_syslog.c |  13 +++++++++----
 src/core/ngx_syslog.h |   2 +-
 2 files changed, 10 insertions(+), 5 deletions(-)

diffs (66 lines):

diff -r 1b8459a53e4b -r 2cb5275bf5e7 src/core/ngx_syslog.c
--- a/src/core/ngx_syslog.c	Wed Sep 17 22:52:02 2014 +0800
+++ b/src/core/ngx_syslog.c	Mon Sep 01 17:55:07 2014 +0400
@@ -234,11 +234,11 @@ ngx_syslog_writer(ngx_log_t *log, ngx_ui
 
     peer = log->wdata;
 
-    if (peer->processing) {
+    if (peer->busy) {
         return;
     }
 
-    peer->processing = 1;
+    peer->busy = 1;
     peer->severity = level - 1;
 
     p = ngx_syslog_add_header(peer, msg);
@@ -254,7 +254,7 @@ ngx_syslog_writer(ngx_log_t *log, ngx_ui
 
     (void) ngx_syslog_send(peer, msg, p - msg);
 
-    peer->processing = 0;
+    peer->busy = 0;
 }
 
 
@@ -267,6 +267,9 @@ ngx_syslog_send(ngx_syslog_peer_t *peer,
         }
     }
 
+    /* log syslog socket events with valid log */
+    peer->conn.log = ngx_cycle->log;
+
     if (ngx_send) {
         return ngx_send(&peer->conn, buf, len);
 
@@ -285,7 +288,6 @@ ngx_syslog_init_peer(ngx_syslog_peer_t *
 
     peer->conn.read = &ngx_syslog_dummy_event;
     peer->conn.write = &ngx_syslog_dummy_event;
-    peer->conn.log = &ngx_syslog_dummy_log;
 
     ngx_syslog_dummy_event.log = &ngx_syslog_dummy_log;
 
@@ -339,6 +341,9 @@ ngx_syslog_cleanup(void *data)
 {
     ngx_syslog_peer_t  *peer = data;
 
+    /* prevents further use of this peer */
+    peer->busy = 1;
+
     if (ngx_close_socket(peer->conn.fd) == -1) {
         ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                       ngx_close_socket_n " failed");
diff -r 1b8459a53e4b -r 2cb5275bf5e7 src/core/ngx_syslog.h
--- a/src/core/ngx_syslog.h	Wed Sep 17 22:52:02 2014 +0800
+++ b/src/core/ngx_syslog.h	Mon Sep 01 17:55:07 2014 +0400
@@ -16,7 +16,7 @@ typedef struct {
 
     ngx_addr_t        server;
     ngx_connection_t  conn;
-    ngx_uint_t        processing;  /* unsigned processing:1; */
+    ngx_uint_t        busy;  /* unsigned busy:1; */
 } ngx_syslog_peer_t;