Added --net-ro-rate command line switch

The default is 0. This works in conjunction with --net-ro-size.

The program will attempt to gather up "net-ro-size" raw bytes before
sending them out over Ethernet. However, to avoid a long wait if the
traffic density is very low, the program will only wait for
"net-ro-rate" 64mS periods since the last send. before sending any data
added to the output buffer since the last send. This allows the user to
tailor the network load to suit their requirements.

dump1090.c

@@ -84,6 +84,7 @@
 
 #define MODES_RAWOUT_BUF_SIZE   (1500)           
 #define MODES_RAWOUT_BUF_FLUSH  (MODES_RAWOUT_BUF_SIZE - 200)
+#define MODES_RAWOUT_BUF_RATE   (1000)            // 1000 * 64mS = 1 Min approx
 
 #define MODES_ICAO_CACHE_LEN 1024 /* Power of two required. */
 #define MODES_ICAO_CACHE_TTL 60   /* Time to live of cached addresses. */
@@ -193,6 +194,8 @@ struct {
     int net_only;                   /* Enable just networking. */
     int net_output_sbs_port;        /* SBS output TCP port. */
     int net_output_raw_size;        /* Minimum Size of the output raw data */     
+    int net_output_raw_rate;        /* Rate (in 64mS increments) of output raw data */     
+    int net_output_raw_rate_count;  /* Rate (in 64mS increments) of output raw data */     
     int net_output_raw_port;        /* Raw output TCP port. */
     int net_input_raw_port;         /* Raw input TCP port. */
     int net_http_port;              /* HTTP port. */
@@ -313,6 +316,7 @@ void modesInitConfig(void) {
     Modes.net_only = 0;
     Modes.net_output_sbs_port = MODES_NET_OUTPUT_SBS_PORT;
     Modes.net_output_raw_size = 0;
+    Modes.net_output_raw_rate = 0;
     Modes.net_output_raw_port = MODES_NET_OUTPUT_RAW_PORT;
     Modes.net_input_raw_port = MODES_NET_INPUT_RAW_PORT;
     Modes.net_http_port = MODES_NET_HTTP_PORT;
@@ -345,8 +349,11 @@ void modesInit(void) {
     }
 
     // Limit the maximum requested raw output size to less than one Ethernet Block 
+    Modes.net_output_raw_rate_count = 0;
     if (Modes.net_output_raw_size > (MODES_RAWOUT_BUF_FLUSH))
       {Modes.net_output_raw_size = MODES_RAWOUT_BUF_FLUSH;}
+    if (Modes.net_output_raw_rate > (MODES_RAWOUT_BUF_RATE))
+      {Modes.net_output_raw_rate = MODES_RAWOUT_BUF_RATE;}
 
     // Clear the buffers that have just been allocated, just in-case
     memset(Modes.icao_cache, 0,   sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2);
@@ -1680,8 +1687,13 @@ void detectModeS(uint16_t *m, uint32_t mlen) {
     //Send any remaining partial raw buffers now
     if (Modes.rawOutUsed)
       {
-      modesSendAllClients(Modes.ros, Modes.rawOut, Modes.rawOutUsed);
+      Modes.net_output_raw_rate_count++;
-      Modes.rawOutUsed = 0;
+      if (Modes.net_output_raw_rate_count > Modes.net_output_raw_rate)
+        {
+        modesSendAllClients(Modes.ros, Modes.rawOut, Modes.rawOutUsed);
+        Modes.rawOutUsed = 0;
+        Modes.net_output_raw_rate_count = 0;
+        }
       }
 }
 
@@ -2224,6 +2236,7 @@ void modesSendBeastOutput(struct modesMessage *mm) {
       {
       modesSendAllClients(Modes.ros, Modes.rawOut, Modes.rawOutUsed);
       Modes.rawOutUsed = 0;
+      Modes.net_output_raw_rate_count = 0;
       }
 }
 
@@ -2257,6 +2270,7 @@ void modesSendRawOutput(struct modesMessage *mm) {
       {
       modesSendAllClients(Modes.ros, Modes.rawOut, Modes.rawOutUsed);
       Modes.rawOutUsed = 0;
+      Modes.net_output_raw_rate_count = 0;
       }
 }
 
@@ -2644,6 +2658,7 @@ void showHelp(void) {
 "--net-beast              TCP raw output in Beast binary format\n"
 "--net-only               Enable just networking, no RTL device or file used\n"
 "--net-ro-size <size>     TCP raw output minimum size (default: 0)\n"
+"--net-ro-rate <rate>     TCP raw output memory flush rate (default: 0)\n"
 "--net-ro-port <port>     TCP raw output listen port (default: 30002)\n"
 "--net-ri-port <port>     TCP raw input listen port  (default: 30001)\n"
 "--net-http-port <port>   HTTP server port (default: 8080)\n"
@@ -2727,6 +2742,8 @@ int main(int argc, char **argv) {
             Modes.net_only = 1;
         } else if (!strcmp(argv[j],"--net-ro-size") && more) {
             Modes.net_output_raw_size = atoi(argv[++j]);
+        } else if (!strcmp(argv[j],"--net-ro-rate") && more) {
+            Modes.net_output_raw_rate = atoi(argv[++j]);
         } else if (!strcmp(argv[j],"--net-ro-port") && more) {
             Modes.net_output_raw_port = atoi(argv[++j]);
         } else if (!strcmp(argv[j],"--net-ri-port") && more) {