AP_Logger: Prepare the maximum number of log files in the config parameter

libraries/AP_Logger/AP_Logger.cpp

@@ -77,6 +77,8 @@ extern const AP_HAL::HAL& hal;
 #define LOGGING_FIRST_DYNAMIC_MSGID 254
 #endif
 
+static constexpr uint16_t MAX_LOG_FILES = 500;
+static constexpr uint16_t MIN_LOG_FILES = 2;
 
 const AP_Param::GroupInfo AP_Logger::var_info[] = {
     // @Param: _BACKEND_TYPE
@@ -176,7 +178,16 @@ const AP_Param::GroupInfo AP_Logger::var_info[] = {
     // @Increment: 0.1
     // @User: Standard
     AP_GROUPINFO("_DARM_RATEMAX",  11, AP_Logger, _params.disarm_ratemax, 0),
-    
+
+    // @Param: _MAX_FILES
+    // @DisplayName: Maximum number of log files
+    // @Description: This sets the maximum number of log file that will be written on dataflash or sd card before starting to rotate log number. Limit is capped at 500 logs.
+    // @Range: 2 500
+    // @Increment: 1
+    // @User: Advanced
+    // @RebootRequired: True
+    AP_GROUPINFO("_MAX_FILES", 12, AP_Logger, _params.max_log_files, MAX_LOG_FILES),
+
     AP_GROUPEND
 };
 
@@ -822,6 +833,14 @@ uint16_t AP_Logger::get_num_logs(void) {
     return backends[0]->get_num_logs();
 }
 
+uint16_t AP_Logger::get_max_num_logs() {
+    const auto max_logs = constrain_uint16(_params.max_log_files.get(), MIN_LOG_FILES, MAX_LOG_FILES);
+    if (_params.max_log_files.get() != max_logs) {
+        _params.max_log_files.set_and_save_ifchanged(static_cast<int16_t>(max_logs));
+    }
+    return static_cast<uint16_t>(_params.max_log_files.get());
+}
+
 /* we're started if any of the backends are started */
 bool AP_Logger::logging_started(void) {
     for (uint8_t i=0; i< _next_backend; i++) {

libraries/AP_Logger/AP_Logger.h

@@ -226,6 +226,7 @@ public:
     uint16_t find_last_log() const;
     void get_log_boundaries(uint16_t log_num, uint32_t & start_page, uint32_t & end_page);
     uint16_t get_num_logs(void);
+    uint16_t get_max_num_logs();
 
     void setVehicle_Startup_Writer(vehicle_startup_message_Writer writer);
 
@@ -336,6 +337,7 @@ public:
         AP_Float mav_ratemax;
         AP_Float blk_ratemax;
         AP_Float disarm_ratemax;
+        AP_Int16 max_log_files;
     } _params;
 
     const struct LogStructure *structure(uint16_t num) const;

libraries/AP_Logger/AP_Logger_Backend.cpp

@@ -599,8 +599,9 @@ uint16_t AP_Logger_Backend::log_num_from_list_entry(const uint16_t list_entry)
     }
 
     uint32_t log_num = oldest_log + list_entry - 1;
-    if (log_num > MAX_LOG_FILES) {
-        log_num -= MAX_LOG_FILES;
+    const auto max_logs_num = _front.get_max_num_logs();
+    if (log_num > (uint32_t)max_logs_num) {
+        log_num -= max_logs_num;
     }
     return (uint16_t)log_num;
 }

libraries/AP_Logger/AP_Logger_Backend.h

@@ -12,8 +12,6 @@
 
 class LoggerMessageWriter_DFLogStart;
 
-#define MAX_LOG_FILES 500
-
 // class to handle rate limiting of log messages
 class AP_Logger_RateLimiter
 {

libraries/AP_Logger/AP_Logger_File.cpp

@@ -234,7 +234,7 @@ bool AP_Logger_File::dirent_to_log_num(const dirent *de, uint16_t &log_num) cons
     }
 
     uint16_t thisnum = strtoul(de->d_name, nullptr, 10);
-    if (thisnum > MAX_LOG_FILES) {
+    if (thisnum > _front.get_max_num_logs()) {
         return false;
     }
     log_num = thisnum;
@@ -330,7 +330,7 @@ void AP_Logger_File::Prep_MinSpace()
         if (avail >= target_free) {
             break;
         }
-        if (count++ > MAX_LOG_FILES+10) {
+        if (count++ > _front.get_max_num_logs() + 10) {
             // *way* too many deletions going on here.  Possible internal error.
             INTERNAL_ERROR(AP_InternalError::error_t::logger_too_many_deletions);
             break;
@@ -360,7 +360,7 @@ void AP_Logger_File::Prep_MinSpace()
             }
         }
         log_to_remove++;
-        if (log_to_remove > MAX_LOG_FILES) {
+        if (log_to_remove > _front.get_max_num_logs()) {
             log_to_remove = 1;
         }
     } while (log_to_remove != first_log_to_remove);
@@ -719,6 +719,7 @@ uint16_t AP_Logger_File::get_num_logs()
             // not a log filename
             continue;
         }
+
         if (thisnum > high && (smallest_above_last == 0 || thisnum < smallest_above_last)) {
             smallest_above_last = thisnum;
         }
@@ -726,7 +727,7 @@ uint16_t AP_Logger_File::get_num_logs()
     AP::FS().closedir(d);
     if (smallest_above_last != 0) {
         // we have wrapped, add in the logs with high numbers
-        ret += (MAX_LOG_FILES - smallest_above_last) + 1;
+        ret += (_front.get_max_num_logs() - smallest_above_last) + 1;
     }
 
     return ret;
@@ -826,7 +827,7 @@ void AP_Logger_File::start_new_log(void)
     if (_get_log_size(log_num) > 0 || log_num == 0) {
         log_num++;
     }
-    if (log_num > MAX_LOG_FILES) {
+    if (log_num > _front.get_max_num_logs()) {
         log_num = 1;
     }
     if (!write_fd_semaphore.take(1)) {
@@ -1115,7 +1116,7 @@ void AP_Logger_File::erase_next(void)
     free(fname);
 
     erase.log_num++;
-    if (erase.log_num <= MAX_LOG_FILES) {
+    if (erase.log_num <= _front.get_max_num_logs()) {
         return;
     }