Make retries in case of read timeout optional and configurable via set-conf option. When not absolutely necessary, they will significantly slow down flushing and normal serial communications with a rig

include/hamlib/rig.h

@@ -2292,8 +2292,8 @@ typedef struct hamlib_port {
             int value;      /*!< Toggle PTT ON or OFF */
         } gpio;             /*!< GPIO attributes */
     } parm;                 /*!< Port parameter union */
-    int client_port;      /*!< client socket port for tcp connection */
-    RIG *rig;             /*!< our parent RIG device */
+    int client_port;        /*!< client socket port for tcp connection */
+    RIG *rig;               /*!< our parent RIG device */
     int asyncio;            /*!< enable asynchronous data handling if true -- async collides with python keyword so _async is used */
 #if defined(_WIN32)
     hamlib_async_pipe_t *sync_data_pipe;         /*!< pipe data structure for synchronous data */
@@ -2304,6 +2304,7 @@ typedef struct hamlib_port {
     int fd_sync_error_write;    /*!< file descriptor for writing synchronous data error codes */
     int fd_sync_error_read;     /*!< file descriptor for reading synchronous data error codes */
 #endif
+    short timeout_retry;    /*!< number of retries to make in case of read timeout errors, some serial interfaces may require this, 0 to disable */
 } hamlib_port_t;
 
  

src/conf.c

@@ -69,6 +69,11 @@ static const struct confparams frontend_cfg_params[] =
         TOK_RETRY, "retry", "Retry", "Max number of retry",
         "0", RIG_CONF_NUMERIC, { .n = { 0, 10, 1 } }
     },
+    {
+        TOK_TIMEOUT_RETRY, "timeout_retry", "Number of retries for read timeouts",
+        "Set the number of retries for data read timeouts that may occur especially with some serial interfaces",
+        "0", RIG_CONF_NUMERIC, { .n = { 0, 100, 1 } }
+    },
     {
         TOK_RANGE_SELECTED, "Selected range list", "Range list#",
         "The tx/rx range list in use",
@@ -738,6 +743,15 @@ static int frontend_set_conf(RIG *rig, token_t token, const char *val)
         rs->tuner_control_pathname = strdup(val); // yeah -- need to free it
         break;
 
+    case TOK_TIMEOUT_RETRY:
+        if (1 != sscanf(val, "%ld", &val_i))
+        {
+            return -RIG_EINVAL;
+        }
+
+        rs->rigport.timeout_retry = val_i;
+        break;
+
     case TOK_OFFSET_VFOA:
         if (1 != sscanf(val, "%ld", &val_i))
         {
@@ -1111,6 +1125,10 @@ static int frontend_get_conf2(RIG *rig, token_t token, char *val, int val_len)
         SNPRINTF(val, val_len, "%d", rs->async_data_enabled);
         break;
 
+    case TOK_TIMEOUT_RETRY:
+        SNPRINTF(val, val_len, "%d", rs->rigport.timeout_retry);
+        break;
+
     default:
         return -RIG_EINVAL;
     }

src/iofunc.c

@@ -1321,7 +1321,7 @@ static int read_string_generic(hamlib_port_t *p,
 
     memset(rxbuffer, 0, rxmax);
 
-    int flag = 0; // we will allow one timeout
+    short timeout_retries = p->timeout_retry;
 
     while (total_count < rxmax - 1) // allow 1 byte for end-of-string
     {
@@ -1332,12 +1332,11 @@ static int read_string_generic(hamlib_port_t *p,
 
         if (result == -RIG_ETIMEOUT)
         {
-            rig_debug(RIG_DEBUG_CACHE, "%s: flag=%d\n", __func__, flag);
-
-            if (flag == 0)
+            if (timeout_retries > 0)
             {
-                flag = 1;
-                hl_usleep(50 * 1000);
+                rig_debug(RIG_DEBUG_CACHE, "%s: retrying read timeout %d/%d\n", __func__,
+                        timeout_retries + 1, p->timeout_retry);
+                hl_usleep(10 * 1000);
                 continue;
             }
 

src/token.h

@@ -95,6 +95,8 @@
 #define TOK_ASYNC        TOKEN_FRONTEND(37)
 /** \brief  Tuner external control pathname */
 #define TOK_TUNER_CONTROL_PATHNAME TOKEN_FRONTEND(38)
+/** \brief Number of retries permitted in case of read timeouts */
+#define TOK_TIMEOUT_RETRY       TOKEN_FRONTEND(39)
 
 /*
  * rig specific tokens