Allow to configure php-fpm slow log trace callers limit

sapi/fpm/fpm/fpm_conf.c

@@ -146,6 +146,7 @@ static struct ini_value_parser_s ini_fpm_pool_options[] = {
 	{ "access.format",             &fpm_conf_set_string,      WPO(access_format) },
 	{ "slowlog",                   &fpm_conf_set_string,      WPO(slowlog) },
 	{ "request_slowlog_timeout",   &fpm_conf_set_time,        WPO(request_slowlog_timeout) },
+	{ "request_slowlog_trace_depth", &fpm_conf_set_integer,     WPO(request_slowlog_trace_depth) },
 	{ "request_terminate_timeout", &fpm_conf_set_time,        WPO(request_terminate_timeout) },
 	{ "rlimit_files",              &fpm_conf_set_integer,     WPO(rlimit_files) },
 	{ "rlimit_core",               &fpm_conf_set_rlimit_core, WPO(rlimit_core) },
@@ -970,6 +971,30 @@ static int fpm_conf_process_all_pools() /* {{{ */
 			}
 		}
 
+		/* request_slowlog_trace_depth */
+		if (wp->config->request_slowlog_trace_depth) {
+#if HAVE_FPM_TRACE
+			if (! (wp->config->slowlog && *wp->config->slowlog)) {
+				zlog(ZLOG_ERROR, "[pool %s] 'slowlog' must be specified for use with 'request_slowlog_trace_depth'", wp->config->name);
+				return -1;
+			}
+#else
+			static int warned = 0;
+
+			if (!warned) {
+				zlog(ZLOG_WARNING, "[pool %s] 'request_slowlog_trace_depth' is not supported on your system", wp->config->name);
+				warned = 1;
+			}
+#endif
+
+			if (wp->config->request_slowlog_trace_depth <= 0) {
+				zlog(ZLOG_ERROR, "[pool %s] 'request_slowlog_trace_depth' (%d) must be a positive value", wp->config->name, wp->config->request_slowlog_trace_depth);
+				return -1;
+			}
+		} else {
+			wp->config->request_slowlog_trace_depth = 20;
+		}
+
 		/* chroot */
 		if (wp->config->chroot && *wp->config->chroot) {
 
@@ -1635,6 +1660,7 @@ static void fpm_conf_dump() /* {{{ */
 		zlog(ZLOG_NOTICE, "\taccess.format = %s",              STR2STR(wp->config->access_format));
 		zlog(ZLOG_NOTICE, "\tslowlog = %s",                    STR2STR(wp->config->slowlog));
 		zlog(ZLOG_NOTICE, "\trequest_slowlog_timeout = %ds",   wp->config->request_slowlog_timeout);
+		zlog(ZLOG_NOTICE, "\trequest_slowlog_trace_depth = %d", wp->config->request_slowlog_trace_depth);
 		zlog(ZLOG_NOTICE, "\trequest_terminate_timeout = %ds", wp->config->request_terminate_timeout);
 		zlog(ZLOG_NOTICE, "\trlimit_files = %d",               wp->config->rlimit_files);
 		zlog(ZLOG_NOTICE, "\trlimit_core = %d",                wp->config->rlimit_core);

sapi/fpm/fpm/fpm_conf.h

@@ -78,6 +78,7 @@ struct fpm_worker_pool_config_s {
 	char *access_format;
 	char *slowlog;
 	int request_slowlog_timeout;
+	int request_slowlog_trace_depth;
 	int request_terminate_timeout;
 	int rlimit_files;
 	int rlimit_core;

sapi/fpm/fpm/fpm_php_trace.c

@@ -42,7 +42,7 @@
 
 static int fpm_php_trace_dump(struct fpm_child_s *child, FILE *slowlog) /* {{{ */
 {
-	int callers_limit = 20;
+	int callers_limit = child->wp->config->request_slowlog_trace_depth;
 	pid_t pid = child->pid;
 	struct timeval tv;
 	static const int buf_size = 1024;

sapi/fpm/www.conf.in

@@ -322,6 +322,10 @@ pm.max_spare_servers = 3
 ; Default Value: 0
 ;request_slowlog_timeout = 0
 
+; Depth of slow log stack trace.
+; Default Value: 20
+;request_slowlog_trace_depth = 20
+
 ; The timeout for serving a single request after which the worker process will
 ; be killed. This option should be used when the 'max_execution_time' ini option
 ; does not stop script execution for some reason. A value of '0' means 'off'.