[PATCH] Added debug_random directive

J Carter jordanc.carter at outlook.com
Tue Jul 18 03:36:02 UTC 2023


On Sat, 15 Jul 2023 03:48:25 +0000
J Carter <jordanc.carter at outlook.com> wrote:

> # HG changeset patch
> # User J Carter <jordanc.carter at outlook.com>
> # Date 1689391559 -3600
> #      Sat Jul 15 04:25:59 2023 +0100
> # Node ID b1ea0a60417e547513654bf9d6bb79714865c780
> # Parent  77c1418916f7817a0d020f28d8a08f278a12fe43
> Added debug_random directive
> 
> This directive enforces for EITHER a percentage of total connections
> OR a percentage of connections matched by debug_connection CIDRs
> to have debug logging enabled.
> 
> This is useful for debugging when nginx is under high load
> (production) - where debugging all connections is not possible without
> disrupting traffic.
> 
> This directive takes a value between 0.00%-100.00% exclusive.
> 

# HG changeset patch
# User J Carter <jordanc.carter at outlook.com>
# Date 1689649226 -3600
#      Tue Jul 18 04:00:26 2023 +0100
# Node ID 87f6f95e0385e6cd37354979ea61cc2435deb430
# Parent  77c1418916f7817a0d020f28d8a08f278a12fe43
Added debug_random directive

Rework of previous patch. Fixed several bugs.

Example usage:

events {
     worker_connections  1024;
     #if uncommented, the percentage applies to connection from lo.
     #debug_connection    127.0.0.0/8;
     debug_random        1%;
}

diff -r 77c1418916f7 -r 87f6f95e0385 src/event/ngx_event.c
--- a/src/event/ngx_event.c	Thu Jun 08 14:58:01 2023 +0400
+++ b/src/event/ngx_event.c	Tue Jul 18 04:00:26 2023 +0100
@@ -30,6 +30,8 @@
 static char *ngx_event_use(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static char *ngx_event_debug_connection(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
+static char *ngx_event_debug_random(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
 
 static void *ngx_event_core_create_conf(ngx_cycle_t *cycle);
 static char *ngx_event_core_init_conf(ngx_cycle_t *cycle, void *conf);
@@ -162,6 +164,13 @@
       0,
       NULL },
 
+      { ngx_string("debug_random"),
+      NGX_EVENT_CONF|NGX_CONF_TAKE1,
+      ngx_event_debug_random,
+      0,
+      0,
+      NULL },
+
       ngx_null_command
 };
 
@@ -496,6 +505,7 @@
     size_t               size, cl;
     ngx_shm_t            shm;
     ngx_time_t          *tp;
+    ngx_cidr_t          *cidr;
     ngx_core_conf_t     *ccf;
     ngx_event_conf_t    *ecf;
 
@@ -507,6 +517,29 @@
                       "using the \"%s\" event method", ecf->name);
     }
 
+    if (ecf->debug_connection.nelts == 0 && ecf->debug_rnd > 0) {
+        cidr = ngx_array_push(&ecf->debug_connection);
+        if (cidr == NULL) {
+            return NGX_ERROR;
+        }
+        /*0.0.0.0/0*/
+        ngx_memzero(cidr, sizeof(ngx_cidr_t));
+        cidr->family = AF_INET;
+
+#ifdef NGX_HAVE_INET6
+        cidr = ngx_array_push(&ecf->debug_connection);
+        if (cidr == NULL) {
+            return NGX_ERROR;
+        }
+        /*::/0*/
+        ngx_memzero(cidr, sizeof(ngx_cidr_t));
+        cidr->family = AF_INET6;
+#endif
+
+    } else if (ecf->debug_connection.nelts > 0 && ecf->debug_rnd == 0) {
+        ecf->debug_rnd = NGX_MAX_INT32_VALUE;
+    }
+
     ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
 
     ngx_timer_resolution = ccf->timer_resolution;
@@ -1254,6 +1287,54 @@
 }
 
 
+static char *
+ngx_event_debug_random(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+#if (NGX_DEBUG)
+    ngx_event_conf_t  *ecf = conf;
+
+    u_char               *c;
+    ngx_int_t             pct;
+    ngx_uint_t            len;
+    ngx_str_t            *value;
+
+    value = cf->args->elts;
+    c = value[1].data;
+    len = value[1].len;
+
+    if (c[len-1] != '%') {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "%V missing '%'",
+                               &value[1]);
+        return NGX_CONF_ERROR;
+    }
+
+    pct = ngx_atofp(c, len-1, 2);
+
+    if (pct == NGX_ERROR
+        || pct == 0
+        || pct > 9999)
+    {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "%V is an invalid value",
+                               &value[1]);
+        return NGX_CONF_ERROR;
+    }
+
+    ecf->debug_rnd = NGX_MAX_INT32_VALUE / 10000 * pct;
+
+#else
+
+    ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+                       "\"debug_random\" is ignored, you need to rebuild "
+                       "nginx using --with-debug option to enable it");
+
+#endif
+
+    return NGX_CONF_OK;
+}
+
+
 static void *
 ngx_event_core_create_conf(ngx_cycle_t *cycle)
 {
@@ -1279,6 +1360,8 @@
         return NULL;
     }
 
+    ecf->debug_rnd = NGX_CONF_UNSET_UINT;
+
 #endif
 
     return ecf;
@@ -1369,5 +1452,7 @@
     ngx_conf_init_value(ecf->accept_mutex, 0);
     ngx_conf_init_msec_value(ecf->accept_mutex_delay, 500);
 
+    ngx_conf_init_uint_value(ecf->debug_rnd, 0);
+
     return NGX_CONF_OK;
 }
diff -r 77c1418916f7 -r 87f6f95e0385 src/event/ngx_event.h
--- a/src/event/ngx_event.h	Thu Jun 08 14:58:01 2023 +0400
+++ b/src/event/ngx_event.h	Tue Jul 18 04:00:26 2023 +0100
@@ -438,6 +438,7 @@
     u_char       *name;
 
 #if (NGX_DEBUG)
+    ngx_uint_t    debug_rnd;
     ngx_array_t   debug_connection;
 #endif
 } ngx_event_conf_t;
diff -r 77c1418916f7 -r 87f6f95e0385 src/event/ngx_event_accept.c
--- a/src/event/ngx_event_accept.c	Thu Jun 08 14:58:01 2023 +0400
+++ b/src/event/ngx_event_accept.c	Tue Jul 18 04:00:26 2023 +0100
@@ -523,6 +523,7 @@
     struct sockaddr_in6  *sin6;
     ngx_uint_t            n;
 #endif
+    ngx_uint_t r = ngx_random();
 
     cidr = ecf->debug_connection.elts;
     for (i = 0; i < ecf->debug_connection.nelts; i++) {
@@ -561,7 +562,9 @@
             break;
         }
 
-        c->log->log_level = NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL;
+        c->log->log_level = (r < ecf->debug_rnd) ?
+                            NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL:
+                            c->log->log_level;
         break;
 
     next:


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