Add ability to set the priority of the socket of the variable server. (#1413)

* Add ability to set the priority of the socket of the variable server.

* Fix build on MacOS.  Apple doesn't have SO_PRIORITY, so set_socket_priority generates an error message.

* Correction to piece of code unrelated to the other commits in this pull request.

---------

Co-authored-by: Stephen Montgomery-Smith <Stephen.J.Montgomery-Smith@nasa.gov>

include/trick/VariableServerListenThread.hh

@@ -28,6 +28,11 @@ namespace Trick {
             unsigned short get_port() ;
             void set_port(unsigned short in_port) ;
 
+#ifndef __APPLE__
+            void set_socket_priority(unsigned short in_socket_priority) ;
+            void apply_socket_priority(TCDevice *listen_device, TCDevice *device);
+#endif
+
             std::string get_user_tag() ;
             const std::string& get_user_tag_ref() ;
             void set_user_tag(std::string in_tag) ;
@@ -75,6 +80,14 @@ namespace Trick {
             /** The mutex to stop accepting new connections during restart\n */
             pthread_mutex_t restart_pause ;     /**<  trick_io(**) */
 
+#ifndef __APPLE__
+            /** Requested variable server socket priority.\n */
+            unsigned short socket_priority ;       /**<  trick_units(--) */
+
+            /** User requested specific socket priority\n */
+            bool user_socket_priority_requested ;  /**<  trick_units(--) */
+#endif
+
     } ;
 
 }

include/trick/tc.h

@@ -48,6 +48,8 @@ PROGRAMMERS:
 #define TC_READWRITE_TIMEOUT            -2
 #define TC_BROKEN_PIPE                  -3
 
+#define TC_COULD_NOT_SET_SOCKET_PRIORITY 16
+
 /* Set default for blocking timeout limit high */
 #define MAX_BLOCKIO_TIMEOUT_LIMIT   1.0e20
 

include/trick/tc_proto.h

@@ -111,6 +111,12 @@ int tc_error(TCDevice * device, int on_off);
 /* copy a device */
 int tc_dev_copy(TCDevice * dest, TCDevice * src);
 
+#ifndef __APPLE__
+/* set priority of socket for a device */
+#define tc_set_socket_priority(listen_device, device, priority) tc_set_socket_priority_(listen_device, device, priority, __FILE__, __LINE__)
+int tc_set_socket_priority_(TCDevice * listen_device, TCDevice * device, int priority, const char *file, int line) ;
+#endif
+
 void *trick_bswap_buffer(void *out, void *in, ATTRIBUTES * attr, int tofrom) ;
 void *trick_bswap_single_parameter(void *out, void *in, ATTRIBUTES * attr, int tofrom) ;
 #ifdef __cplusplus

include/trick/variable_server_proto.h

@@ -12,6 +12,7 @@ const char * var_server_get_hostname(void) ;
 unsigned short var_server_get_port(void) ;
 void var_server_set_port(unsigned short port) ;
 void var_server_set_source_address(const char * address) ;
+void var_server_set_socket_priority(unsigned short port) ;
 
 const char * var_server_get_user_tag(void) ;
 void var_server_set_user_tag(const char * tag) ;

trick_source/sim_services/VariableServer/VariableServerListenThread.cpp

@@ -43,6 +43,13 @@ void Trick::VariableServerListenThread::set_port(unsigned short in_port) {
     user_port_requested = true ;
 }
 
+#ifndef __APPLE__
+void Trick::VariableServerListenThread::set_socket_priority(unsigned short in_socket_priority) {
+    socket_priority = in_socket_priority;
+    user_socket_priority_requested = true ;
+}
+#endif
+
 std::string Trick::VariableServerListenThread::get_user_tag() {
     return user_tag ;
 }
@@ -253,3 +260,8 @@ void Trick::VariableServerListenThread::dump( std::ostream & oss ) {
     Trick::ThreadBase::dump(oss) ;
 }
 
+#ifndef __APPLE__
+void Trick::VariableServerListenThread::apply_socket_priority(TCDevice *listen_device, TCDevice *device) {
+    if (user_socket_priority_requested) tc_set_socket_priority(listen_device, device, socket_priority);
+}
+#endif

trick_source/sim_services/VariableServer/VariableServerThread_loop.cpp

@@ -38,6 +38,7 @@ void * Trick::VariableServerThread::thread_body() {
     if ( listen_dev->socket_type == SOCK_STREAM ) {
         tc_accept(listen_dev, &connection);
         tc_blockio(&connection, TC_COMM_ALL_OR_NOTHING);
+        vs->get_listen_thread().apply_socket_priority(listen_dev, &connection);
     }
     connection_accepted = true ;
 

trick_source/sim_services/VariableServer/var_server_ext.cpp

@@ -437,6 +437,19 @@ extern "C" void var_server_set_port(unsigned short port) {
     the_vs->get_listen_thread().set_port(port);
 }
 
+/**
+ * @relates Trick::VariableServer
+ * @copydoc Trick::VariableServer::set_socket_priority
+ * C wrapper Trick::VariableServer::set_socket_priority
+ */
+extern "C" void var_server_set_socket_priority(unsigned short socket_priority) {
+#ifndef __APPLE__
+    the_vs->get_listen_thread().set_socket_priority(socket_priority);
+#else
+    message_publish(MSG_ERROR,"var_server_set_socket_priority not available on MacOS\n") ;
+#endif
+}
+
 /**
  * @relates Trick::VariableServer
  * @copydoc Trick::VariableServer::set_listen_socket

trick_source/trick_utils/comm/CMakeLists.txt

@@ -21,6 +21,7 @@ set( TRICKCOMM_SRC
   src/tc_read
   src/tc_read_byteswap
   src/tc_set_blockio
+  src/tc_set_socket_priority
   src/tc_write
   src/tc_write_byteswap
   src/trick_bswap_buffer

trick_source/trick_utils/comm/src/tc_accept.c

@@ -42,11 +42,8 @@ int tc_accept_(TCDevice * listen_device, TCDevice * device, const char *file, in
     }
 
     /* Turn off data buffering. This causes data to be sent immediately rather than queing it up until the transmit
-       buffer is filled. */
+       buffer is filled, and check for error conditon on set socket option */
-    setsockopt(the_socket, IPPROTO_TCP, TCP_NODELAY, (const void *) &on, (socklen_t) sizeof(on));
+    if (setsockopt(the_socket, IPPROTO_TCP, TCP_NODELAY, (const void *) &on, (socklen_t) sizeof(on)) < 0) {
-
-    /* Check for error conditon on set socket option */
-    if (the_socket < 0) {
         if (tc_errno == TRICKCOMM_EWOULDBLOCK) {
             trick_error_report(listen_device->error_handler,
                                TRICK_ERROR_ALERT, file,

trick_source/trick_utils/comm/src/tc_set_socket_priority.c

@@ -0,0 +1,35 @@
+
+/*
+ * Set the priority of a socket.
+ */
+
+#ifndef __APPLE__
+
+#ifndef __WIN32__
+#include <errno.h>
+#include <netinet/tcp.h>
+#include <unistd.h>
+#endif
+
+#include "trick/tc.h"
+#include "trick/tc_proto.h"
+#include "trick/trick_byteswap.h"
+
+int tc_set_socket_priority_(TCDevice * listen_device, TCDevice * device, int priority, const char *file, int line)
+{
+    char client_str[TC_TAG_LENGTH + 256];
+
+    snprintf(client_str, sizeof(client_str), "(ID = %d  tag = %s)", listen_device->client_id, listen_device->client_tag);
+
+    if (setsockopt(device->socket, SOL_SOCKET, SO_PRIORITY, &priority, sizeof(priority)) < 0) {
+        trick_error_report(listen_device->error_handler,
+                           TRICK_ERROR_ALERT, file,
+                           line, "tc_set_socket_priority: %s: error on set socket option: " "TC_COULD_NOT_SET_SOCKET_PRIORITY", client_str);
+        return (TC_COULD_NOT_SET_SOCKET_PRIORITY);
+    }
+
+    return(TC_SUCCESS);
+
+}
+
+#endif