AP_Logger: keep pointer to link rather than using its ->chan

libraries/AP_Logger/AP_Logger.cpp

@@ -727,7 +727,7 @@ void AP_Logger::handle_mavlink_msg(GCS_MAVLINK &link, const mavlink_message_t &m
 {
     switch (msg.msgid) {
     case MAVLINK_MSG_ID_REMOTE_LOG_BLOCK_STATUS:
-        FOR_EACH_BACKEND(remote_log_block_status_msg(link.get_chan(), msg));
+        FOR_EACH_BACKEND(remote_log_block_status_msg(link, msg));
         break;
     case MAVLINK_MSG_ID_LOG_REQUEST_LIST:
         FALLTHROUGH;

libraries/AP_Logger/AP_Logger_Backend.h

@@ -72,7 +72,7 @@ public:
 #endif
 
      // for Logger_MAVlink
-    virtual void remote_log_block_status_msg(const mavlink_channel_t chan,
+    virtual void remote_log_block_status_msg(const GCS_MAVLINK &link,
                                              const mavlink_message_t &msg) { }
     // end for Logger_MAVlink
 

libraries/AP_Logger/AP_Logger_MAVLink.cpp

@@ -220,7 +220,7 @@ void AP_Logger_MAVLink::stop_logging()
     }
 }
 
-void AP_Logger_MAVLink::handle_ack(const mavlink_channel_t chan,
+void AP_Logger_MAVLink::handle_ack(const GCS_MAVLINK &link,
                                    const mavlink_message_t &msg,
                                    uint32_t seqno)
 {
@@ -245,7 +245,7 @@ void AP_Logger_MAVLink::handle_ack(const mavlink_channel_t chan,
             _sending_to_client = true;
             _target_system_id = msg.sysid;
             _target_component_id = msg.compid;
-            _chan = chan;
+            _link = &link;
             _next_seq_num = 0;
             start_new_log_reset_variables();
             _last_response_time = AP_HAL::millis();
@@ -266,7 +266,7 @@ void AP_Logger_MAVLink::handle_ack(const mavlink_channel_t chan,
     }
 }
 
-void AP_Logger_MAVLink::remote_log_block_status_msg(const mavlink_channel_t chan,
+void AP_Logger_MAVLink::remote_log_block_status_msg(const GCS_MAVLINK &link,
                                                     const mavlink_message_t& msg)
 {
     mavlink_remote_log_block_status_t packet;
@@ -277,7 +277,7 @@ void AP_Logger_MAVLink::remote_log_block_status_msg(const mavlink_channel_t chan
     if(packet.status == 0){
         handle_retry(packet.seqno);
     } else{
-        handle_ack(chan, msg, packet.seqno);
+        handle_ack(link, msg, packet.seqno);
     }
     semaphore.give();
 }
@@ -537,17 +537,24 @@ void AP_Logger_MAVLink::periodic_1Hz()
 //TODO: handle full txspace properly
 bool AP_Logger_MAVLink::send_log_block(struct dm_block &block)
 {
-    mavlink_channel_t chan = mavlink_channel_t(_chan - MAVLINK_COMM_0);
     if (!_initialised) {
        return false;
     }
-    if (!HAVE_PAYLOAD_SPACE(chan, REMOTE_LOG_DATA_BLOCK)) {
+    if (_link == nullptr) {
+        INTERNAL_ERROR(AP_InternalError::error_t::flow_of_control);
         return false;
     }
-    if (comm_get_txspace(chan) < 500) {
+    // don't completely fill buffers - and also ensure there's enough
+    // room to send at least one packet:
+    const uint16_t min_payload_space = 500;
+    static_assert(MAVLINK_MSG_ID_REMOTE_LOG_DATA_BLOCK_LEN <= min_payload_space,
+                  "minimum allocated space is less than payload length");
+    if (_link->txspace() < min_payload_space) {
         return false;
     }
+
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+    // deliberately fail 10% of the time in SITL:
     if (rand() < 0.1) {
         return false;
     }
@@ -561,7 +568,7 @@ bool AP_Logger_MAVLink::send_log_block(struct dm_block &block)
     hal.util->perf_begin(_perf_packing);
 
     mavlink_message_t msg;
-    mavlink_status_t *chan_status = mavlink_get_channel_status(chan);
+    mavlink_status_t *chan_status = mavlink_get_channel_status(_link->get_chan());
     uint8_t saved_seq = chan_status->current_tx_seq;
     chan_status->current_tx_seq = mavlink_seq++;
     // Debug("Sending block (%d)", block.seqno);
@@ -587,7 +594,7 @@ bool AP_Logger_MAVLink::send_log_block(struct dm_block &block)
     // problem and stop attempting to log
     _last_send_time = AP_HAL::millis();
 
-    _mavlink_resend_uart(chan, &msg);
+    _mavlink_resend_uart(_link->get_chan(), &msg);
 
     return true;
 }

libraries/AP_Logger/AP_Logger_MAVLink.h

@@ -59,7 +59,7 @@ public:
     int16_t get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data) override { return 0; }
     uint16_t get_num_logs(void) override { return 0; }
 
-    void remote_log_block_status_msg(const mavlink_channel_t chan, const mavlink_message_t& msg) override;
+    void remote_log_block_status_msg(const GCS_MAVLINK &link, const mavlink_message_t& msg) override;
     void vehicle_was_disarmed() override {}
 
 protected:
@@ -76,7 +76,7 @@ private:
         struct dm_block *next;
     };
     bool send_log_block(struct dm_block &block);
-    void handle_ack(const mavlink_channel_t chan, const mavlink_message_t &msg, uint32_t seqno);
+    void handle_ack(const GCS_MAVLINK &link, const mavlink_message_t &msg, uint32_t seqno);
     void handle_retry(uint32_t block_num);
     void do_resends(uint32_t now);
     void free_all_blocks();
@@ -123,7 +123,8 @@ private:
     bool logging_enabled() const override { return true; }
     bool logging_failed() const override;
 
-    mavlink_channel_t _chan;
+    const GCS_MAVLINK *_link;
+
     uint8_t _target_system_id;
     uint8_t _target_component_id;