Improve signal and thread handling (#36)

Improve signal and thread handling

Signed-off-by: Joakim Roubert <joakimr@axis.com>

LICENSE

@@ -187,7 +187,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright [2022] [Axis Communications AB]
+   Copyright [2023] [Axis Communications AB]
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.md

@@ -1,4 +1,4 @@
-*Copyright (C) 2022, Axis Communications AB, Lund, Sweden. All Rights Reserved.*
+*Copyright (C) 2023, Axis Communications AB, Lund, Sweden. All Rights Reserved.*
 
 # Modbus ACAP
 

manifest.json

@@ -7,7 +7,7 @@
             "vendor": "Axis Communications AB",
             "embeddedSdkVersion": "2.0",
             "runMode": "respawn",
-            "version": "1.1.0"
+            "version": "1.1.1"
         },
         "configuration": {
             "paramConfig": [

modbus_client.c

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

modbus_client.h

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

modbus_server.c

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <modbus.h>
 #include <pthread.h>
 #include <unistd.h>
@@ -26,13 +27,14 @@
 static gboolean run_server = FALSE;
 static pthread_t modbus_server_thread_id = -1;
 static guint32 modbus_port = 0;
+static modbus_t *srv_ctx = NULL;
 
 static void *run_modbus_server(void *run)
 {
     assert(NULL != run);
-    modbus_t *srv_ctx;
     modbus_mapping_t *mb_mapping = NULL;
     int s;
+    int flags;
 
     assert(1024 <= modbus_port && 65535 >= modbus_port);
     LOG_I("Trying to create Modbus TCP context for all IP addresss and port %u ...", modbus_port);
@@ -51,13 +53,26 @@ static void *run_modbus_server(void *run)
         goto server_exit;
     }
 
-    LOG_I("Accept Modbus TCP connection ...");
-    if (-1 == modbus_tcp_accept(srv_ctx, &s))
+    flags = fcntl(s, F_GETFL, 0);
+    if (-1 == fcntl(s, F_SETFL, flags | O_NONBLOCK))
     {
-        LOG_E("%s/%s: modbus_tcp_accept failed (%s)", __FILE__, __FUNCTION__, modbus_strerror(errno));
+        LOG_E("%s/%s: fcntl failed for socket (%s)", __FILE__, __FUNCTION__, strerror(errno));
         goto server_exit;
     }
 
+    LOG_I("Accept Modbus TCP connection ...");
+    while (*((gboolean *)run))
+    {
+        // Attempt to accept a client connection (non-blocking)
+        if (0 < modbus_tcp_accept(srv_ctx, &s))
+        {
+            break;
+        }
+
+        // Sleep briefly to avoid busy-waiting
+        usleep(200000); // Sleep for 200 ms
+    }
+
     LOG_I("Allocate mapping ...");
     mb_mapping = modbus_mapping_new(1, 0, 0, 0);
     if (NULL == mb_mapping)
@@ -151,4 +166,5 @@ void modbus_server_stop()
         pthread_join(modbus_server_thread_id, NULL);
     }
     modbus_server_thread_id = -1;
+    srv_ctx = NULL;
 }

modbus_server.h

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

modbusacap.c

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,12 +30,14 @@ enum Mode
     CLIENT = 1
 };
 
+static GMainLoop *main_loop = NULL;
 static AXEventHandler *ehandler;
 static AXParameter *axparameter = NULL;
 static gboolean initialized = FALSE;
 static guint8 mode = 0;
 static guint32 port = 0;
 static guint subscription;
+static pthread_mutex_t lock;
 
 static void open_syslog(const char *app_name)
 {
@@ -44,7 +46,8 @@ static void open_syslog(const char *app_name)
 
 static void close_syslog(void)
 {
-    LOG_I("Exiting!");
+    LOG_I("%s/%s: Exiting!", __FILE__, __FUNCTION__);
+    closelog();
 }
 
 static void event_callback(guint subscription, AXEvent *event, void *data)
@@ -207,6 +210,22 @@ static void scenario_callback(const gchar *name, const gchar *value, void *data)
     setup_event_subscription(&subscription, scenario);
 }
 
+static void close_current_modbus(const guint8 m)
+{
+    switch (m)
+    {
+    case SERVER:
+        modbus_server_stop();
+        break;
+    case CLIENT:
+        modbus_client_cleanup();
+        break;
+    default:
+        LOG_E("%s/%s: %u is not a known mode", __FILE__, __FUNCTION__, mode);
+        break;
+    }
+}
+
 static void server_callback(const gchar *name, const gchar *value, void *data)
 {
     (void)data;
@@ -216,13 +235,16 @@ static void server_callback(const gchar *name, const gchar *value, void *data)
         return;
     }
 
+    pthread_mutex_lock(&lock);
+    close_current_modbus(mode);
     LOG_I("%s/%s: Got new %s (%s)", __FILE__, __FUNCTION__, name, value);
 
     // Setup Modbus for this mode
     if (initialized && !setup_modbus(mode, port, value))
     {
         LOG_I("%s/%s: Failed to setup Modbus", __FILE__, __FUNCTION__);
     }
+    pthread_mutex_unlock(&lock);
 }
 
 static void mode_callback(const gchar *name, const gchar *value, void *data)
@@ -234,6 +256,8 @@ static void mode_callback(const gchar *name, const gchar *value, void *data)
         return;
     }
 
+    pthread_mutex_lock(&lock);
+    close_current_modbus(mode);
     mode = atoi(value);
     assert(0 == mode || 1 == mode);
     LOG_I("%s/%s: Got new %s (%s)", __FILE__, __FUNCTION__, name, mode == SERVER ? "server" : "client");
@@ -244,6 +268,7 @@ static void mode_callback(const gchar *name, const gchar *value, void *data)
         LOG_I("%s/%s: Failed to setup Modbus", __FILE__, __FUNCTION__);
         assert(FALSE);
     }
+    pthread_mutex_unlock(&lock);
 }
 
 static void port_callback(const gchar *name, const gchar *value, void *data)
@@ -255,6 +280,8 @@ static void port_callback(const gchar *name, const gchar *value, void *data)
         return;
     }
 
+    pthread_mutex_lock(&lock);
+    close_current_modbus(mode);
     port = atoi(value);
     assert(1024 <= port || 65535 >= port);
     LOG_I("%s/%s: Got new %s (%u)", __FILE__, __FUNCTION__, name, port);
@@ -265,6 +292,7 @@ static void port_callback(const gchar *name, const gchar *value, void *data)
         LOG_I("%s/%s: Failed to setup Modbus", __FILE__, __FUNCTION__);
         assert(FALSE);
     }
+    pthread_mutex_unlock(&lock);
 }
 
 static gboolean setup_param(const gchar *name, AXParameterCallback callbackfn)
@@ -298,27 +326,54 @@ static gboolean setup_param(const gchar *name, AXParameterCallback callbackfn)
     return TRUE;
 }
 
-static void init_signals(void)
+static void signal_handler(gint signal_num)
+{
+    switch (signal_num)
+    {
+    case SIGTERM:
+    case SIGABRT:
+    case SIGINT:
+        g_main_loop_quit(main_loop);
+        break;
+    default:
+        break;
+    }
+}
+
+static gboolean signal_handler_init(void)
 {
-    struct sigaction sa;
+    struct sigaction sa = {0};
+
+    if (-1 == sigemptyset(&sa.sa_mask))
+    {
+        LOG_E("%s/%s: Failed to initialize signal handler: %s", __FILE__, __FUNCTION__, strerror(errno));
+        return FALSE;
+    }
+
+    sa.sa_handler = signal_handler;
+
+    if (0 > sigaction(SIGTERM, &sa, NULL) || 0 > sigaction(SIGABRT, &sa, NULL) || 0 > sigaction(SIGINT, &sa, NULL))
+    {
+        LOG_E("%s/%s: Failed to install signal handler: %s", __FILE__, __FUNCTION__, strerror(errno));
+        return FALSE;
+    }
 
-    sigemptyset(&sa.sa_mask);
-    sigaddset(&sa.sa_mask, SIGPIPE);
-    sa.sa_flags = 0;
-    sa.sa_handler = SIG_IGN;
-    sigaction(SIGPIPE, &sa, NULL);
+    return TRUE;
 }
 
 int main(int argc, char **argv)
 {
     GError *error = NULL;
-    int ret = 0;
-
-    init_signals();
-
     char *app_name = basename(argv[0]);
     open_syslog(app_name);
 
+    int ret = EXIT_SUCCESS;
+    if (!signal_handler_init())
+    {
+        ret = EXIT_FAILURE;
+        goto exit_syslog;
+    }
+
     // Create event handler
     ehandler = ax_event_handler_new();
 
@@ -328,7 +383,7 @@ int main(int argc, char **argv)
     {
         LOG_E("%s/%s: ax_parameter_new failed (%s)", __FILE__, __FUNCTION__, error->message);
         g_error_free(error);
-        ret = 1;
+        ret = EXIT_FAILURE;
         goto exit_ehandler;
     }
     // clang-format off
@@ -338,7 +393,7 @@ int main(int argc, char **argv)
         !setup_param("Server", server_callback))
     // clang-format on
     {
-        ret = 1;
+        ret = EXIT_FAILURE;
         goto exit_param;
     }
 
@@ -348,10 +403,12 @@ int main(int argc, char **argv)
 
     // Main loop
     LOG_I("%s/%s: Ready", __FILE__, __FUNCTION__);
-    GMainLoop *loop = g_main_loop_new(NULL, FALSE);
-    g_main_loop_run(loop);
+    main_loop = g_main_loop_new(NULL, FALSE);
+    g_main_loop_run(main_loop);
 
     // Cleanup and controlled shutdown
+    LOG_I("%s/%s: Unreference main loop ...", __FILE__, __FUNCTION__);
+    g_main_loop_unref(main_loop);
 exit_param:
     LOG_I("%s/%s: Free parameter handler ...", __FILE__, __FUNCTION__);
     ax_parameter_free(axparameter);
@@ -363,7 +420,7 @@ int main(int argc, char **argv)
     // Cleanup Modbus
     modbus_client_cleanup();
     modbus_server_stop();
-
+exit_syslog:
     LOG_I("%s/%s: Closing syslog ...", __FILE__, __FUNCTION__);
     close_syslog();
 

modbusacap_common.h

@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2022, Axis Communications AB, Lund, Sweden
+ * Copyright (C) 2023, Axis Communications AB, Lund, Sweden
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.