DataFlash: delete oldest file rather than the lowest-numbered file

Also reference log numbers by their list index to accomodate log number
wrapping in DataFlash_File

libraries/DataFlash/DataFlash.cpp

@@ -49,7 +49,7 @@ uint16_t DataFlash_Class::bufferspace_available(void) {
     return backend->bufferspace_available();
 }
 
-uint16_t DataFlash_Class::find_last_log(void) {
+uint16_t DataFlash_Class::find_last_log() const {
     return backend->find_last_log();
 }
 void DataFlash_Class::get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page) {

libraries/DataFlash/DataFlash.h

@@ -63,7 +63,7 @@ public:
     bool WriteCriticalBlock(const void *pBuffer, uint16_t size);
 
     // high level interface
-    uint16_t find_last_log(void);
+    uint16_t find_last_log() const;
     void get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page);
     void get_log_info(uint16_t log_num, uint32_t &size, uint32_t &time_utc);
     int16_t get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data);

libraries/DataFlash/DataFlash_Backend.h

@@ -43,13 +43,13 @@ public:
     virtual bool WritePrioritisedBlock(const void *pBuffer, uint16_t size, bool is_critical) = 0;
 
     // high level interface
-    virtual uint16_t find_last_log(void) = 0;
+    virtual uint16_t find_last_log() = 0;
     virtual void get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page) = 0;
     virtual void get_log_info(uint16_t log_num, uint32_t &size, uint32_t &time_utc) = 0;
     virtual int16_t get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data) = 0;
-    virtual uint16_t get_num_logs(void) = 0;
+    virtual uint16_t get_num_logs() = 0;
 #ifndef DATAFLASH_NO_CLI
-    virtual void LogReadProcess(uint16_t log_num,
+    virtual void LogReadProcess(const uint16_t list_entry,
                                 uint16_t start_page, uint16_t end_page,
                                 print_mode_fn printMode,
                                 AP_HAL::BetterStream *port) = 0;

libraries/DataFlash/DataFlash_Block.h

@@ -31,15 +31,15 @@ public:
     bool WritePrioritisedBlock(const void *pBuffer, uint16_t size, bool is_critical);
 
     // high level interface
-    uint16_t find_last_log(void);
+    uint16_t find_last_log() override;
     void get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page);
     void get_log_info(uint16_t log_num, uint32_t &size, uint32_t &time_utc);
     int16_t get_log_data_raw(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data);
     int16_t get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data);
-    uint16_t get_num_logs(void);
+    uint16_t get_num_logs() override;
     uint16_t start_new_log(void);
 #ifndef DATAFLASH_NO_CLI
-    void LogReadProcess(uint16_t log_num,
+    void LogReadProcess(const uint16_t list_entry,
                         uint16_t start_page, uint16_t end_page, 
                         print_mode_fn print_mode,
                         AP_HAL::BetterStream *port);

libraries/DataFlash/DataFlash_File.cpp

@@ -5,6 +5,11 @@
 
    This uses posix file IO to create log files called logs/NN.bin in the
    given directory
+
+   SD Card Rates on PixHawk:
+    - deletion rate seems to be ~50 files/second.
+    - stat seems to be ~150/second
+    - readdir loop of 511 entry directory ~62,000 microseconds
  */
 
 #include <AP_HAL/AP_HAL.h>
@@ -141,6 +146,29 @@ void DataFlash_File::Init(const struct LogStructure *structure, uint8_t num_type
     hal.scheduler->register_io_process(FUNCTOR_BIND_MEMBER(&DataFlash_File::_io_timer, void));
 }
 
+bool DataFlash_File::file_exists(const char *filename) const
+{
+    struct stat st;
+    if (stat(filename, &st) == -1) {
+        // hopefully errno==ENOENT.  If some error occurs it is
+        // probably better to assume this file exists.
+        return false;
+    }
+    return true;
+}
+
+bool DataFlash_File::log_exists(const uint16_t lognum) const
+{
+    char *filename = _log_file_name(lognum);
+    if (filename == NULL) {
+        // internal_error();
+        return false; // ?!
+    }
+    bool ret = file_exists(filename);
+    free(filename);
+    return ret;
+}
+
 void DataFlash_File::periodic_fullrate(const uint32_t now)
 {
     DataFlash_Backend::push_log_blocks();
@@ -158,37 +186,56 @@ bool DataFlash_File::CardInserted(void)
     return _initialised && !_open_error;
 }
 
-uint64_t DataFlash_File::disk_space_avail()
+// returns the amount of disk space available in _log_directory (in bytes)
+// returns -1 on error
+int64_t DataFlash_File::disk_space_avail()
 {
     struct statfs stats;
     if (statfs(_log_directory, &stats) < 0) {
         return -1;
     }
-    return (((uint64_t)stats.f_bavail) * stats.f_bsize);
+    return (((int64_t)stats.f_bavail) * stats.f_bsize);
 }
 
-uint64_t DataFlash_File::disk_space()
+// returns the total amount of disk space (in use + available) in
+// _log_directory (in bytes).
+// returns -1 on error
+int64_t DataFlash_File::disk_space()
 {
     struct statfs stats;
     if (statfs(_log_directory, &stats) < 0) {
         return -1;
     }
-    return (((uint64_t)stats.f_blocks) * stats.f_bsize);
+    return (((int64_t)stats.f_blocks) * stats.f_bsize);
 }
 
+// returns the available space in _log_directory as a percentage
+// returns -1.0f on error
 float DataFlash_File::avail_space_percent()
 {
-    uint64_t avail = disk_space_avail();
-    uint64_t space = disk_space();
+    int64_t avail = disk_space_avail();
+    if (avail == -1) {
+        return -1.0f;
+    }
+    int64_t space = disk_space();
+    if (space == -1) {
+        return -1.0f;
+    }
 
     return (avail/(float)space) * 100;
 }
 
-// find_first_log - find lowest-numbered log in _log_directory
+// find_oldest_log - find oldest log in _log_directory
 // returns 0 if no log was found
-uint16_t DataFlash_File::find_first_log(void)
+uint16_t DataFlash_File::find_oldest_log()
 {
-    // iterate through directory entries to find lowest log number.
+    uint16_t last_log_num = find_last_log();
+    if (last_log_num == 0) {
+        return 0;
+    }
+
+    uint16_t current_oldest_log = 0; // 0 is invalid
+
     // We could count up to find_last_log(), but if people start
     // relying on the min_avail_space_percent feature we could end up
     // doing a *lot* of asprintf()s and stat()s
@@ -199,7 +246,6 @@ uint16_t DataFlash_File::find_first_log(void)
     }
 
     // we only remove files which look like xxx.BIN
-    uint32_t lowest_number = (uint32_t)-1; // unsigned integer wrap
     for (struct dirent *de=readdir(d); de; de=readdir(d)) {
         uint8_t length = strlen(de->d_name);
         if (length < 5) {
@@ -212,30 +258,55 @@ uint16_t DataFlash_File::find_first_log(void)
         }
 
         uint16_t thisnum = strtoul(de->d_name, NULL, 10);
-        if (thisnum < lowest_number) {
-            lowest_number = thisnum;
+        if (thisnum > MAX_LOG_FILES) {
+            // ignore files above our official maximum...
+            continue;
+        }
+        if (current_oldest_log == 0) {
+            current_oldest_log = thisnum;
+        } else {
+            if (current_oldest_log <= last_log_num) {
+                if (thisnum > last_log_num) {
+                    current_oldest_log = thisnum;
+                } else if (thisnum < current_oldest_log) {
+                    current_oldest_log = thisnum;
+                }
+            } else { // current_oldest_log > last_log_num
+                if (thisnum > last_log_num) {
+                    if (thisnum < current_oldest_log) {
+                        current_oldest_log = thisnum;
+                    }
+                }
+            }
         }
     }
     closedir(d);
 
-    if (lowest_number == (uint32_t)-1) {
-        return 0;
-    }
-    return lowest_number;
+    return current_oldest_log;
 }
 
 void DataFlash_File::Prep_MinSpace()
 {
-    uint16_t log_to_remove = find_first_log();
-    if (log_to_remove == 0) {
+    const uint16_t first_log_to_remove = find_oldest_log();
+    if (first_log_to_remove == 0) {
         // no files to remove
         return;
     }
+
+    uint16_t log_to_remove = first_log_to_remove;
+
     uint16_t count = 0;
-    while (avail_space_percent() < min_avail_space_percent) {
-        if (count++ > 500) {
+    do {
+        float avail = avail_space_percent();
+        if (is_equal(avail, -1.0f)) {
+            // internal_error()
+            break;
+        }
+        if (avail >= min_avail_space_percent) {
+            break;
+        }
+        if (count++ > MAX_LOG_FILES+10) {
             // *way* too many deletions going on here.  Possible internal error.
-            // deletion rate seems to be ~50 files/second.
             // internal_error();
             break;
         }
@@ -244,28 +315,29 @@ void DataFlash_File::Prep_MinSpace()
             // internal_error();
             break;
         }
-        hal.console->printf("Removing (%s) for minimum-space requirements\n",
-                              filename_to_remove);
-        if (unlink(filename_to_remove) == -1) {
-            hal.console->printf("Failed to remove %s: (%d/%d) %s\n", filename_to_remove, errno, ENOENT, strerror(errno));
-            free(filename_to_remove);
-            if (errno == ENOENT) {
-                log_to_remove = find_first_log();
-                if (log_to_remove == 0) {
-                    // out of files to remove...
+        if (file_exists(filename_to_remove)) {
+            hal.console->printf("Removing (%s) for minimum-space requirements (%.2f%% < %.0f%%)\n",
+                                filename_to_remove, avail, min_avail_space_percent);
+            if (unlink(filename_to_remove) == -1) {
+                hal.console->printf("Failed to remove %s: %s\n", filename_to_remove, strerror(errno));
+                free(filename_to_remove);
+                if (errno == ENOENT) {
+                    // corruption - should always have a continuous
+                    // sequence of files...  however, there may be still
+                    // files out there, so keep going.
+                } else {
+                    // internal_error();
                     break;
                 }
-                // corruption - should always have a continuous
-                // sequence of files...  however, we now have a file
-                // we can delete, so keep going.
             } else {
-                break;
+                free(filename_to_remove);
             }
-        } else {
-            free(filename_to_remove);
-            log_to_remove++;
         }
-    }
+        log_to_remove++;
+        if (log_to_remove > MAX_LOG_FILES) {
+            log_to_remove = 1;
+        }
+    } while (log_to_remove != first_log_to_remove);
 }
 
 void DataFlash_File::Prep() {
@@ -294,7 +366,7 @@ bool DataFlash_File::NeedPrep()
   construct a log file name given a log number. 
   Note: Caller must free.
  */
-char *DataFlash_File::_log_file_name(uint16_t log_num)
+char *DataFlash_File::_log_file_name(const uint16_t log_num) const
 {
     char *buf = NULL;
     if (asprintf(&buf, "%s/%u.BIN", _log_directory, (unsigned)log_num) == 0) {
@@ -307,7 +379,7 @@ char *DataFlash_File::_log_file_name(uint16_t log_num)
   return path name of the lastlog.txt marker file
   Note: Caller must free.
  */
-char *DataFlash_File::_lastlog_file_name(void)
+char *DataFlash_File::_lastlog_file_name(void) const
 {
     char *buf = NULL;
     if (asprintf(&buf, "%s/LASTLOG.TXT", _log_directory) == 0) {
@@ -322,7 +394,7 @@ void DataFlash_File::EraseAll()
 {
     uint16_t log_num;
     stop_logging();
-    for (log_num=0; log_num<MAX_LOG_FILES; log_num++) {
+    for (log_num=1; log_num<=MAX_LOG_FILES; log_num++) {
         char *fname = _log_file_name(log_num);
         if (fname == NULL) {
             break;
@@ -421,7 +493,7 @@ bool DataFlash_File::ReadBlock(void *pkt, uint16_t size)
 /*
   find the highest log number
  */
-uint16_t DataFlash_File::find_last_log(void)
+uint16_t DataFlash_File::find_last_log()
 {
     unsigned ret = 0;
     char *fname = _lastlog_file_name();
@@ -442,20 +514,7 @@ uint16_t DataFlash_File::find_last_log(void)
     return ret;
 }
 
-bool DataFlash_File::_log_exists(uint16_t log_num)
-{
-    char *fname = _log_file_name(log_num);
-    if (fname == NULL) {
-        return 0;
-    }
-    struct stat st;
-    // stat return 0 if the file exists:
-    bool ret = ::stat(fname, &st) ? false : true;
-    free(fname);
-    return ret;
-}
-
-uint32_t DataFlash_File::_get_log_size(uint16_t log_num)
+uint32_t DataFlash_File::_get_log_size(const uint16_t log_num) const
 {
     char *fname = _log_file_name(log_num);
     if (fname == NULL) {
@@ -470,7 +529,7 @@ uint32_t DataFlash_File::_get_log_size(uint16_t log_num)
     return st.st_size;
 }
 
-uint32_t DataFlash_File::_get_log_time(uint16_t log_num)
+uint32_t DataFlash_File::_get_log_time(const uint16_t log_num) const
 {
     char *fname = _log_file_name(log_num);
     if (fname == NULL) {
@@ -485,11 +544,41 @@ uint32_t DataFlash_File::_get_log_time(uint16_t log_num)
     return st.st_mtime;
 }
 
+/*
+  convert a list entry number back into a log number (which can then
+  be converted into a filename).  A "list entry number" is a sequence
+  where the oldest log has a number of 1, the second-from-oldest 2,
+  and so on.  Thus the highest list entry number is equal to the
+  number of logs.
+*/
+uint16_t DataFlash_File::_log_num_from_list_entry(const uint16_t list_entry)
+{
+    uint16_t oldest_log = find_oldest_log();
+    if (oldest_log == 0) {
+        // We don't have any logs...
+        return 0;
+    }
+
+    uint32_t log_num = oldest_log + list_entry - 1;
+    if (log_num > MAX_LOG_FILES) {
+        log_num -= MAX_LOG_FILES;
+    }
+    return (uint16_t)log_num;
+}
+
 /*
   find the number of pages in a log
  */
-void DataFlash_File::get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page)
+void DataFlash_File::get_log_boundaries(const uint16_t list_entry, uint16_t & start_page, uint16_t & end_page)
 {
+    const uint16_t log_num = _log_num_from_list_entry(list_entry);
+    if (log_num == 0) {
+        // that failed - probably no logs
+        start_page = 0;
+        end_page = 0;
+        return;
+    }
+
     start_page = 0;
     end_page = _get_log_size(log_num) / DATAFLASH_PAGE_SIZE;
 }
@@ -497,11 +586,18 @@ void DataFlash_File::get_log_boundaries(uint16_t log_num, uint16_t & start_page,
 /*
   find the number of pages in a log
  */
-int16_t DataFlash_File::get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data)
+int16_t DataFlash_File::get_log_data(const uint16_t list_entry, const uint16_t page, const uint32_t offset, const uint16_t len, uint8_t *data)
 {
     if (!_initialised || _open_error) {
         return -1;
     }
+
+    const uint16_t log_num = _log_num_from_list_entry(list_entry);
+    if (log_num == 0) {
+        // that failed - probably no logs
+        return -1;
+    }
+
     if (_read_fd != -1 && log_num != _read_fd_log_num) {
         ::close(_read_fd);
         _read_fd = -1;
@@ -559,8 +655,16 @@ int16_t DataFlash_File::get_log_data(uint16_t log_num, uint16_t page, uint32_t o
 /*
   find size and date of a log
  */
-void DataFlash_File::get_log_info(uint16_t log_num, uint32_t &size, uint32_t &time_utc)
+void DataFlash_File::get_log_info(const uint16_t list_entry, uint32_t &size, uint32_t &time_utc)
 {
+    uint16_t log_num = _log_num_from_list_entry(list_entry);
+    if (log_num == 0) {
+        // that failed - probably no logs
+        size = 0;
+        time_utc = 0;
+        return;
+    }
+
     size = _get_log_size(log_num);
     time_utc = _get_log_time(log_num);
 }
@@ -570,14 +674,24 @@ void DataFlash_File::get_log_info(uint16_t log_num, uint32_t &size, uint32_t &ti
 /*
   get the number of logs - note that the log numbers must be consecutive
  */
-uint16_t DataFlash_File::get_num_logs(void)
+uint16_t DataFlash_File::get_num_logs()
 {
-    uint16_t ret;
+    uint16_t ret = 0;
     uint16_t high = find_last_log();
-    for (ret=0; ret<high; ret++) {
-        if (!_log_exists(high - ret)) {
+    uint16_t i;
+    for (i=high; i>0; i--) {
+        if (! log_exists(i)) {
             break;
         }
+        ret++;
+    }
+    if (i == 0) {
+        for (i=MAX_LOG_FILES; i>high; i--) {
+            if (! log_exists(i)) {
+                break;
+            }
+            ret++;
+        }
     }
     return ret;
 }
@@ -654,7 +768,7 @@ uint16_t DataFlash_File::start_new_log(void)
 /*
   Read the log and print it on port
 */
-void DataFlash_File::LogReadProcess(uint16_t log_num,
+void DataFlash_File::LogReadProcess(const uint16_t list_entry,
                                     uint16_t start_page, uint16_t end_page, 
                                     print_mode_fn print_mode,
                                     AP_HAL::BetterStream *port)
@@ -663,6 +777,12 @@ void DataFlash_File::LogReadProcess(uint16_t log_num,
     if (!_initialised || _open_error) {
         return;
     }
+
+    const uint16_t log_num = _log_num_from_list_entry(list_entry);
+    if (log_num == 0) {
+        return;
+    }
+
     if (_read_fd != -1) {
         ::close(_read_fd);
         _read_fd = -1;
@@ -752,7 +872,6 @@ void DataFlash_File::ShowDeviceInfo(AP_HAL::BetterStream *port)
 void DataFlash_File::ListAvailableLogs(AP_HAL::BetterStream *port)
 {
     uint16_t num_logs = get_num_logs();
-    int16_t last_log_num = find_last_log();
 
     if (num_logs == 0) {
         port->printf_P(PSTR("\nNo logs\n\n"));
@@ -760,20 +879,17 @@ void DataFlash_File::ListAvailableLogs(AP_HAL::BetterStream *port)
     }
     port->printf_P(PSTR("\n%u logs\n"), (unsigned)num_logs);
 
-    for (uint16_t i=num_logs; i>=1; i--) {
-        uint16_t log_num = last_log_num - i + 1;
-        off_t size;
-
+    for (uint16_t i=1; i<=num_logs; i++) {
+        uint16_t log_num = _log_num_from_list_entry(i);
         char *filename = _log_file_name(log_num);
         if (filename != NULL) {
-            size = _get_log_size(log_num);
                 struct stat st;
                 if (stat(filename, &st) == 0) {
                     struct tm *tm = gmtime(&st.st_mtime);
-                    port->printf_P(PSTR("Log %u in %s of size %u %u/%u/%u %u:%u\n"), 
-                                   (unsigned)log_num, 
+                    port->printf_P(PSTR("Log %u in %s of size %u %u/%u/%u %u:%u\n"),
+                                   (unsigned)i,
                                    filename,
-                                   (unsigned)size,
+                                   (unsigned)st.st_size,
                                    (unsigned)tm->tm_year+1900,
                                    (unsigned)tm->tm_mon+1,
                                    (unsigned)tm->tm_mday,

libraries/DataFlash/DataFlash_File.h

@@ -36,14 +36,13 @@ public:
     uint16_t bufferspace_available();
 
     // high level interface
-    uint16_t find_last_log(void);
+    uint16_t find_last_log() override;
     void get_log_boundaries(uint16_t log_num, uint16_t & start_page, uint16_t & end_page);
     void get_log_info(uint16_t log_num, uint32_t &size, uint32_t &time_utc);
     int16_t get_log_data(uint16_t log_num, uint16_t page, uint32_t offset, uint16_t len, uint8_t *data);
-    uint16_t get_num_logs(void);
-    bool _log_exists(uint16_t log_num);
+    uint16_t get_num_logs() override;
     uint16_t start_new_log(void);
-    void LogReadProcess(uint16_t log_num,
+    void LogReadProcess(const uint16_t log_num,
                         uint16_t start_page, uint16_t end_page, 
                         print_mode_fn print_mode,
                         AP_HAL::BetterStream *port);
@@ -71,13 +70,18 @@ private:
     */
     bool ReadBlock(void *pkt, uint16_t size);
 
+    uint16_t _log_num_from_list_entry(const uint16_t list_entry);
+
     // possibly time-consuming preparations handling
     void Prep_MinSpace();
-    uint16_t find_first_log(void);
-    uint64_t disk_space_avail();
-    uint64_t disk_space();
+    uint16_t find_oldest_log();
+    int64_t disk_space_avail();
+    int64_t disk_space();
     float avail_space_percent();
 
+    bool file_exists(const char *filename) const;
+    bool log_exists(const uint16_t lognum) const;
+
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL || CONFIG_HAL_BOARD == HAL_BOARD_LINUX
     // I always seem to have less than 10% free space on my laptop:
     const float min_avail_space_percent = 0.1f;
@@ -93,10 +97,10 @@ private:
     uint32_t _last_write_time;
 
     /* construct a file name given a log number. Caller must free. */
-    char *_log_file_name(uint16_t log_num);
-    char *_lastlog_file_name(void);
-    uint32_t _get_log_size(uint16_t log_num);
-    uint32_t _get_log_time(uint16_t log_num);
+    char *_log_file_name(const uint16_t log_num) const;
+    char *_lastlog_file_name() const;
+    uint32_t _get_log_size(const uint16_t log_num) const;
+    uint32_t _get_log_time(const uint16_t log_num) const;
 
     void stop_logging(void);