# HG changeset patch
# User J Carter <jordanc.carter@outlook.com>
# Date 1702098547 0
# Sat Dec 09 05:09:07 2023 +0000
# Node ID d9275e982a7188a1ea7855295ffa93362ea9830f
# Parent f366007dd23a6ce8e8427c1b3042781b618a2ade
Events: debug_random directive

This directive enables debug logging for only a percentage of connections that
match debug_connection/s.

This directive is useful for sample style debugging of nginx when under high
load scenarios, where logging all connections would incur excessive overhead.

This directive takes a value between 0.01%-99.99% inclusive.

Example usage:

events {
worker_connections 1024;
debug_connection 0.0.0.0/0;
debug_connection ::0;
debug_random 1%;
}

diff -r f366007dd23a -r d9275e982a71 src/event/ngx_event.c
--- a/src/event/ngx_event.c Tue Nov 14 15:26:02 2023 +0400
+++ b/src/event/ngx_event.c Sat Dec 09 05:09:07 2023 +0000
@@ -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
};

@@ -1254,6 +1263,51 @@
}


+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;
+
+ ngx_int_t n;
+ ngx_str_t *value;
+
+ if (ecf->debug_percent != NGX_CONF_UNSET_UINT) {
+ return "is duplicate";
+ }
+
+ value = cf->args->elts;
+
+ if (value[1].len == 0 || value[1].data[value[1].len - 1] != '%') {
+ goto invalid;
+ }
+
+ n = ngx_atofp(value[1].data, value[1].len - 1, 2);
+ if (n == NGX_ERROR || n == 0 || n > 9999) {
+ goto invalid;
+ }
+
+ ecf->debug_percent = n;
+
+ return NGX_CONF_OK;
+
+invalid:
+
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+ "invalid percent value \"%V\"", &value[1]);
+
+#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_ERROR;
+}
+
+
static void *
ngx_event_core_create_conf(ngx_cycle_t *cycle)
{
@@ -1279,6 +1333,8 @@
return NULL;
}

+ ecf->debug_percent = NGX_CONF_UNSET_UINT;
+
#endif

return ecf;
@@ -1369,5 +1425,9 @@
ngx_conf_init_value(ecf->accept_mutex, 0);
ngx_conf_init_msec_value(ecf->accept_mutex_delay, 500);

+#if (NGX_DEBUG)
+ ngx_conf_init_uint_value(ecf->debug_percent, 0);
+#endif
+
return NGX_CONF_OK;
}
diff -r f366007dd23a -r d9275e982a71 src/event/ngx_event.h
--- a/src/event/ngx_event.h Tue Nov 14 15:26:02 2023 +0400
+++ b/src/event/ngx_event.h Sat Dec 09 05:09:07 2023 +0000
@@ -438,6 +438,7 @@
u_char *name;

#if (NGX_DEBUG)
+ ngx_uint_t debug_percent;
ngx_array_t debug_connection;
#endif
} ngx_event_conf_t;
diff -r f366007dd23a -r d9275e982a71 src/event/ngx_event_accept.c
--- a/src/event/ngx_event_accept.c Tue Nov 14 15:26:02 2023 +0400
+++ b/src/event/ngx_event_accept.c Sat Dec 09 05:09:07 2023 +0000
@@ -561,6 +561,12 @@
break;
}

+ if (ecf->debug_percent
+ && ecf->debug_percent <= (ngx_uint_t) ngx_random() % 10000)
+ {
+ break;
+ }
+
c->log->log_level = NGX_LOG_DEBUG_CONNECTION|NGX_LOG_DEBUG_ALL;
break;

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