Add support for sending the SIGRTMIN signal to trigger log rotation.

Closes #2337. Thanks to Evgeny S.

ChangeLog.txt

@@ -80,6 +80,8 @@ Broker:
 - Add more efficient keepalive check.
 - Send DISCONNECT With session-takeover return code to MQTT v5 clients when a
   client connects with the same client id. Closes #2340.
+- Add support for sending the SIGRTMIN signal to trigger log rotation.
+  Closes #2337.
 
 Client library:
 - Add MOSQ_OPT_DISABLE_SOCKETPAIR to allow the disabling of the socketpair

man/mosquitto.8.xml

@@ -693,6 +693,18 @@
 					for details.</para>
 					<para>If TLS certificates are in use, then mosquitto will
 					also reload certificate on receiving a SIGHUP.</para>
+					<para>
+						The logs will also be closed and reopened.
+					</para>
+				</listitem>
+			</varlistentry>
+			<varlistentry>
+				<term>SIGRTMIN</term>
+				<listitem>
+					<para>
+						Upon receiving the SIGRTMIN signal, mosquitto will
+						close and reopen the logs to support log rotation.
+					</para>
 				</listitem>
 			</varlistentry>
 			<varlistentry>

src/loop.c

@@ -55,11 +55,6 @@ Contributors:
 #include "time_mosq.h"
 #include "util_mosq.h"
 
-extern bool flag_reload;
-#ifdef WITH_PERSISTENCE
-extern bool flag_db_backup;
-#endif
-extern bool flag_tree_print;
 extern int g_run;
 
 #if defined(WITH_WEBSOCKETS) && WITH_WEBSOCKETS == WS_IS_WEBSOCKETS && LWS_LIBRARY_VERSION_NUMBER == 3002000
@@ -231,38 +226,7 @@ int mosquitto_main_loop(struct mosquitto__listener_sock *listensock, int listens
 		}
 #endif
 
-#ifdef WITH_PERSISTENCE
+		signal__flag_check();
-		if(flag_db_backup){
-			persist__backup(false);
-			flag_db_backup = false;
-		}
-#endif
-		if(flag_reload){
-			log__printf(NULL, MOSQ_LOG_INFO, "Reloading config.");
-			config__read(db.config, true);
-			listeners__reload_all_certificates();
-			mosquitto_security_cleanup(true);
-			mosquitto_security_init(true);
-			mosquitto_security_apply();
-			log__close(db.config);
-			log__init(db.config);
-			keepalive__cleanup();
-			keepalive__init();
-#ifdef WITH_CJSON
-			broker_control__reload();
-#endif
-#ifdef WITH_BRIDGE
-			bridge__reload();
-#endif
-			flag_reload = false;
-		}
-		if(flag_tree_print){
-			sub__tree_print(db.subs, 0);
-			flag_tree_print = false;
-#ifdef WITH_XTREPORT
-			xtreport();
-#endif
-		}
 #if defined(WITH_WEBSOCKETS) && WITH_WEBSOCKETS == WS_IS_LWS
 		for(i=0; i<db.config->listener_count; i++){
 			/* Extremely hacky, should be using the lws provided external poll

src/mosquitto_broker_internal.h

@@ -896,6 +896,7 @@ void session_expiry__send_all(void);
  * Signals
  * ============================================================ */
 void signal__setup(void);
+void signal__flag_check(void);
 
 /* ============================================================
  * Window service and signal related functions

src/signals.c

@@ -33,11 +33,12 @@ Contributors:
 
 extern int g_run;
 
-bool flag_reload = false;
+static bool flag_reload = false;
+static bool flag_log_rotate = false;
 #ifdef WITH_PERSISTENCE
-bool flag_db_backup = false;
+static bool flag_db_backup = false;
 #endif
-bool flag_tree_print = false;
+static bool flag_tree_print = false;
 
 static void handle_signal(int signal)
 {
@@ -55,6 +56,10 @@ static void handle_signal(int signal)
 #endif
 	}else if(signal == SIGUSR2){
 		flag_tree_print = true;
+#ifdef SIGRTMIN
+	}else if(signal == SIGRTMIN){
+		flag_log_rotate = true;
+#endif
 	}
 }
 
@@ -71,11 +76,55 @@ void signal__setup(void)
 	signal(SIGUSR2, handle_signal);
 	signal(SIGPIPE, SIG_IGN);
 #endif
+#ifdef SIGRTMIN
+	signal(SIGRTMIN, handle_signal);
+#endif
 #ifdef WIN32
 	CreateThread(NULL, 0, SigThreadProc, NULL, 0, NULL);
 #endif
 }
 
+void signal__flag_check(void)
+{
+#ifdef WITH_PERSISTENCE
+	if(flag_db_backup){
+		persist__backup(false);
+		flag_db_backup = false;
+	}
+#endif
+	if(flag_log_rotate){
+		log__close(db.config);
+		log__init(db.config);
+		flag_log_rotate = false;
+	}
+	if(flag_reload){
+		log__printf(NULL, MOSQ_LOG_INFO, "Reloading config.");
+		config__read(db.config, true);
+		listeners__reload_all_certificates();
+		mosquitto_security_cleanup(true);
+		mosquitto_security_init(true);
+		mosquitto_security_apply();
+		log__close(db.config);
+		log__init(db.config);
+		keepalive__cleanup();
+		keepalive__init();
+#ifdef WITH_CJSON
+		broker_control__reload();
+#endif
+#ifdef WITH_BRIDGE
+		bridge__reload();
+#endif
+		flag_reload = false;
+	}
+	if(flag_tree_print){
+		sub__tree_print(db.subs, 0);
+		flag_tree_print = false;
+#ifdef WITH_XTREPORT
+		xtreport();
+#endif
+	}
+}
+
 /*
  *
  * Signalling mosquitto process on Win32.