AP_Logger: added LOG_DARM_RATEMAX

this sets the logging rate max when disarmed. In combination with
LOG_DISARMED=3 it gives a very nice setup to get always on logging
with very little addition to the log sizes. It is particularly useful
in combination with LOG_REPLAY=1

libraries/AP_Logger/AP_Logger.cpp

@@ -164,6 +164,15 @@ const AP_Param::GroupInfo AP_Logger::var_info[] = {
     AP_GROUPINFO("_BLK_RATEMAX", 10, AP_Logger, _params.blk_ratemax, 0),
 #endif
 
+    // @Param: _DARM_RATEMAX
+    // @DisplayName: Maximum logging rate when disarmed
+    // @Description: This sets the maximum rate that streaming log messages will be logged to any backend when disarmed. A value of zero means that the normal backend rate limit is applied.
+    // @Units: Hz
+    // @Range: 0 1000
+    // @Increment: 0.1
+    // @User: Standard
+    AP_GROUPINFO("_DARM_RATEMAX",  11, AP_Logger, _params.disarm_ratemax, 0),
+    
     AP_GROUPEND
 };
 
@@ -1461,19 +1470,11 @@ void AP_Logger::Write_Error(LogErrorSubsystem sub_system,
 }
 
 /*
-  return true if we should log while disarmed
+  return true if we are in a logging persistance state, where we keep
+  logging after a disarm or an arming failure
  */
-bool AP_Logger::log_while_disarmed(void) const
+bool AP_Logger::in_log_persistance(void) const
 {
-    if (_force_log_disarmed) {
-        return true;
-    }
-    if (_params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED ||
-        _params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED_DISCARD ||
-        (_params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED_NOT_USB && !hal.gpio->usb_connected())) {
-        return true;
-    }
-
     uint32_t now = AP_HAL::millis();
     uint32_t persist_ms = HAL_LOGGER_ARM_PERSIST*1000U;
     if (_force_long_log_persist) {
@@ -1495,6 +1496,24 @@ bool AP_Logger::log_while_disarmed(void) const
     return false;
 }
 
+
+/*
+  return true if we should log while disarmed
+ */
+bool AP_Logger::log_while_disarmed(void) const
+{
+    if (_force_log_disarmed) {
+        return true;
+    }
+    if (_params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED ||
+        _params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED_DISCARD ||
+        (_params.log_disarmed == LogDisarmed::LOG_WHILE_DISARMED_NOT_USB && !hal.gpio->usb_connected())) {
+        return true;
+    }
+
+    return in_log_persistance();
+}
+
 #if HAL_LOGGER_FILE_CONTENTS_ENABLED
 void AP_Logger::prepare_at_arming_sys_file_logging()
 {

libraries/AP_Logger/AP_Logger.h

@@ -311,6 +311,7 @@ public:
     void set_force_log_disarmed(bool force_logging) { _force_log_disarmed = force_logging; }
     void set_long_log_persist(bool b) { _force_long_log_persist = b; }
     bool log_while_disarmed(void) const;
+    bool in_log_persistance(void) const;
     uint8_t log_replay(void) const { return _params.log_replay; }
 
     vehicle_startup_message_Writer _vehicle_messages;
@@ -336,6 +337,7 @@ public:
         AP_Float file_ratemax;
         AP_Float mav_ratemax;
         AP_Float blk_ratemax;
+        AP_Float disarm_ratemax;
     } _params;
 
     const struct LogStructure *structure(uint16_t num) const;

libraries/AP_Logger/AP_Logger_Backend.cpp

@@ -671,22 +671,24 @@ void AP_Logger_Backend::df_stats_log() {
 
 
 // class to handle rate limiting of log messages
-AP_Logger_RateLimiter::AP_Logger_RateLimiter(const AP_Logger &_front, const AP_Float &_limit_hz)
-    : front(_front), rate_limit_hz(_limit_hz)
+AP_Logger_RateLimiter::AP_Logger_RateLimiter(const AP_Logger &_front, const AP_Float &_limit_hz, const AP_Float &_disarm_limit_hz)
+    : front(_front),
+      rate_limit_hz(_limit_hz),
+      disarm_rate_limit_hz(_disarm_limit_hz)
 {
 }
 
 /*
   return false if a streaming message should not be sent yet
  */
-bool AP_Logger_RateLimiter::should_log_streaming(uint8_t msgid)
+bool AP_Logger_RateLimiter::should_log_streaming(uint8_t msgid, float rate_hz)
 {
     if (front._log_pause) {
         return false;
     }
     const uint16_t now = AP_HAL::millis16();
     uint16_t delta_ms = now - last_send_ms[msgid];
-    if (delta_ms < 1000.0 / rate_limit_hz.get()) {
+    if (is_positive(rate_hz) && delta_ms < 1000.0 / rate_hz) {
         // too soon
         return false;
     }
@@ -700,7 +702,13 @@ bool AP_Logger_RateLimiter::should_log_streaming(uint8_t msgid)
  */
 bool AP_Logger_RateLimiter::should_log(uint8_t msgid, bool writev_streaming)
 {
-    if (rate_limit_hz <= 0 && !front._log_pause) {
+    float rate_hz = rate_limit_hz;
+    if (!hal.util->get_soft_armed() &&
+        !AP::logger().in_log_persistance() &&
+        !is_zero(disarm_rate_limit_hz)) {
+        rate_hz = disarm_rate_limit_hz;
+    }
+    if (!is_positive(rate_hz) && !front._log_pause) {
         // no rate limiting if not paused and rate is zero(user changed the parameter)
         return true;
     }
@@ -728,7 +736,7 @@ bool AP_Logger_RateLimiter::should_log(uint8_t msgid, bool writev_streaming)
     last_sched_count[msgid] = sched_ticks;
 #endif
 
-    bool ret = should_log_streaming(msgid);
+    bool ret = should_log_streaming(msgid, rate_hz);
     if (ret) {
         last_return.set(msgid);
     } else {

libraries/AP_Logger/AP_Logger_Backend.h

@@ -12,15 +12,16 @@ class LoggerMessageWriter_DFLogStart;
 class AP_Logger_RateLimiter
 {
 public:
-    AP_Logger_RateLimiter(const AP_Logger &_front, const AP_Float &_limit_hz);
+    AP_Logger_RateLimiter(const AP_Logger &_front, const AP_Float &_limit_hz, const AP_Float &_disarm_limit_hz);
 
     // return true if message passes the rate limit test
     bool should_log(uint8_t msgid, bool writev_streaming);
-    bool should_log_streaming(uint8_t msgid);
+    bool should_log_streaming(uint8_t msgid, float rate_hz);
 
 private:
     const AP_Logger &front;
     const AP_Float &rate_limit_hz;
+    const AP_Float &disarm_rate_limit_hz;
 
     // time in ms we last sent this message
     uint16_t last_send_ms[256];

libraries/AP_Logger/AP_Logger_Block.cpp

@@ -307,9 +307,12 @@ void AP_Logger_Block::periodic_1Hz()
 {
     AP_Logger_Backend::periodic_1Hz();
 
-    if (rate_limiter == nullptr && (_front._params.blk_ratemax > 0 || _front._log_pause)) {
+    if (rate_limiter == nullptr &&
+        (_front._params.blk_ratemax > 0 ||
+         _front._params.disarm_ratemax > 0 ||
+         _front._log_pause)) {
         // setup rate limiting if log rate max > 0Hz or log pause of streaming entries is requested
-        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.blk_ratemax);
+        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.blk_ratemax, _front._params.disarm_ratemax);
     }
     
     if (!io_thread_alive()) {

libraries/AP_Logger/AP_Logger_File.cpp

@@ -164,9 +164,12 @@ void AP_Logger_File::periodic_1Hz()
         }
     }
 
-    if (rate_limiter == nullptr && (_front._params.file_ratemax > 0 || _front._log_pause)) {
+    if (rate_limiter == nullptr &&
+        (_front._params.file_ratemax > 0 ||
+         _front._params.disarm_ratemax > 0 ||
+         _front._log_pause)) {
         // setup rate limiting if log rate max > 0Hz or log pause of streaming entries is requested
-        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.file_ratemax);
+        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.file_ratemax, _front._params.disarm_ratemax);
     }
 }
 

libraries/AP_Logger/AP_Logger_MAVLink.cpp

@@ -530,9 +530,12 @@ void AP_Logger_MAVLink::periodic_10Hz(const uint32_t now)
 }
 void AP_Logger_MAVLink::periodic_1Hz()
 {
-    if (rate_limiter == nullptr && (_front._params.mav_ratemax > 0 || _front._log_pause)) {
+    if (rate_limiter == nullptr &&
+        (_front._params.mav_ratemax > 0 ||
+         _front._params.disarm_ratemax > 0 ||
+         _front._log_pause)) {
         // setup rate limiting if log rate max > 0Hz or log pause of streaming entries is requested
-        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.mav_ratemax);
+        rate_limiter = new AP_Logger_RateLimiter(_front, _front._params.mav_ratemax, _front._params.disarm_ratemax);
     }
 
     if (_sending_to_client &&