Add file_size() function to FileIOMessageWriter (#1367)

* Add file_size() function to FileIOMessageWriter

* Modify help statement for -s to indicate blf behaves differently

* Open max_container_size in blf writer to API via kwargs

Co-authored-by: j-c-cook <jack-c-cook@protonmail.com>

Author: zariiii9003

can/io/blf.py

@@ -17,7 +17,7 @@
 import datetime
 import time
 import logging
-from typing import List, BinaryIO, Generator, Union, Tuple, Optional, cast
+from typing import List, BinaryIO, Generator, Union, Tuple, Optional, cast, Any
 
 from ..message import Message
 from ..util import len2dlc, dlc2len, channel2int
@@ -370,6 +370,8 @@ def __init__(
         append: bool = False,
         channel: int = 1,
         compression_level: int = -1,
+        *args: Any,
+        **kwargs: Any
     ) -> None:
         """
         :param file: a path-like object or as file-like object to write to
@@ -400,6 +402,9 @@ def __init__(
         self.compression_level = compression_level
         self._buffer: List[bytes] = []
         self._buffer_size = 0
+        # If max container size is located in kwargs, then update the instance
+        if kwargs.get("max_container_size", False):
+            self.max_container_size = kwargs["max_container_size"]
         if append:
             # Parse file header
             data = self.file.read(FILE_HEADER_STRUCT.size)
@@ -566,6 +571,10 @@ def _flush(self):
         self.uncompressed_size += LOG_CONTAINER_STRUCT.size
         self.uncompressed_size += len(uncompressed_data)
 
+    def file_size(self) -> int:
+        """Return an estimate of the current file size in bytes."""
+        return self.file.tell() + self._buffer_size
+
     def stop(self):
         """Stops logging and closes the file."""
         self._flush()

can/io/generic.py

@@ -89,6 +89,10 @@ def __init__(self, file: can.typechecking.AcceptedIOType, mode: str = "wt") -> N
 
         super().__init__(file, mode)
 
+    def file_size(self) -> int:
+        """Return an estimate of the current file size in bytes."""
+        return self.file.tell()
+
 
 # pylint: disable=too-few-public-methods
 class MessageReader(BaseIOHandler, Iterable[can.Message], metaclass=ABCMeta):

can/io/logger.py

@@ -326,7 +326,7 @@ def should_rollover(self, msg: Message) -> bool:
         if self.max_bytes <= 0:
             return False
 
-        if self.writer.file.tell() >= self.max_bytes:
+        if self.writer.file_size() >= self.max_bytes:
             return True
 
         return False

can/logger.py

@@ -191,8 +191,9 @@ def main() -> None:
         "--file_size",
         dest="file_size",
         type=int,
-        help="Maximum file size in bytes. Rotate log file when size threshold "
-        "is reached.",
+        help="Maximum file size in bytes (or for the case of blf, maximum "
+        "buffer size before compression and flush to file). Rotate log "
+        "file when size threshold is reached.",
         default=None,
     )