randomaccessfile: drop explicit passing of file description

The goal of this object is to manage IO, we still have to open the file if
necessary, but this is all internal now.

mercurial/revlogutils/randomaccessfile.py

@@ -1,159 +1,155 b''
 # Copyright Mercurial Contributors
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import contextlib
 
 from ..i18n import _
 from .. import (
     error,
     util,
 )
 
 
 _MAX_CACHED_CHUNK_SIZE = 1048576  # 1 MiB
 
 PARTIAL_READ_MSG = _(
     b'partial read of revlog %s; expected %d bytes from offset %d, got %d'
 )
 
 
 def _is_power_of_two(n):
     return (n & (n - 1) == 0) and n != 0
 
 
 class randomaccessfile:
     """Accessing arbitrary chuncks of data within a file, with some caching"""
 
     def __init__(
         self,
         opener,
         filename,
         default_cached_chunk_size,
         initial_cache=None,
     ):
         # Required by bitwise manipulation below
         assert _is_power_of_two(default_cached_chunk_size)
 
         self.opener = opener
         self.filename = filename
         self.default_cached_chunk_size = default_cached_chunk_size
         self.writing_handle = None  # This is set from revlog.py
         self.reading_handle = None
         self._cached_chunk = b''
         self._cached_chunk_position = 0  # Offset from the start of the file
         if initial_cache:
             self._cached_chunk_position, self._cached_chunk = initial_cache
 
     def clear_cache(self):
         self._cached_chunk = b''
         self._cached_chunk_position = 0
 
     def _open(self, mode=b'r'):
         """Return a file object"""
         return self.opener(self.filename, mode=mode)
 
     @contextlib.contextmanager
-    def _open_read(self, existing_file_obj=None):
+    def _read_handle(self):
         """File object suitable for reading data"""
-        # Use explicit file handle, if given.
-        if existing_file_obj is not None:
-            yield existing_file_obj
-
         # Use a file handle being actively used for writes, if available.
         # There is some danger to doing this because reads will seek the
         # file. However, revlog._writeentry performs a SEEK_END before all
         # writes, so we should be safe.
-        elif self.writing_handle:
+        if self.writing_handle:
             yield self.writing_handle
 
         elif self.reading_handle:
             yield self.reading_handle
 
         # Otherwise open a new file handle.
         else:
             with self._open() as fp:
                 yield fp
 
     @contextlib.contextmanager
     def reading(self):
         """Context manager that keeps the file open for reading"""
         if (
             self.reading_handle is None
             and self.writing_handle is None
             and self.filename is not None
         ):
             with self._open() as fp:
                 self.reading_handle = fp
                 try:
                     yield
                 finally:
                     self.reading_handle = None
         else:
             yield
 
-    def read_chunk(self, offset, length, existing_file_obj=None):
+    def read_chunk(self, offset, length):
         """Read a chunk of bytes from the file.
 
         Accepts an absolute offset, length to read, and an optional existing
         file handle to read from.
 
         If an existing file handle is passed, it will be seeked and the
         original seek position will NOT be restored.
 
         Returns a str or buffer of raw byte data.
 
         Raises if the requested number of bytes could not be read.
         """
         end = offset + length
         cache_start = self._cached_chunk_position
         cache_end = cache_start + len(self._cached_chunk)
         # Is the requested chunk within the cache?
         if cache_start <= offset and end <= cache_end:
             if cache_start == offset and end == cache_end:
                 return self._cached_chunk  # avoid a copy
             relative_start = offset - cache_start
             return util.buffer(self._cached_chunk, relative_start, length)
 
-        return self._read_and_update_cache(offset, length, existing_file_obj)
+        return self._read_and_update_cache(offset, length)
 
-    def _read_and_update_cache(self, offset, length, existing_file_obj=None):
+    def _read_and_update_cache(self, offset, length):
         # Cache data both forward and backward around the requested
         # data, in a fixed size window. This helps speed up operations
         # involving reading the revlog backwards.
         real_offset = offset & ~(self.default_cached_chunk_size - 1)
         real_length = (
             (offset + length + self.default_cached_chunk_size)
             & ~(self.default_cached_chunk_size - 1)
         ) - real_offset
-        with self._open_read(existing_file_obj) as file_obj:
+        with self._read_handle() as file_obj:
             file_obj.seek(real_offset)
             data = file_obj.read(real_length)
 
         self._add_cached_chunk(real_offset, data)
 
         relative_offset = offset - real_offset
         got = len(data) - relative_offset
         if got < length:
             message = PARTIAL_READ_MSG % (self.filename, length, offset, got)
             raise error.RevlogError(message)
 
         if offset != real_offset or real_length != length:
             return util.buffer(data, relative_offset, length)
         return data
 
     def _add_cached_chunk(self, offset, data):
         """Add to or replace the cached data chunk.
 
         Accepts an absolute offset and the data that is at that location.
         """
         if (
             self._cached_chunk_position + len(self._cached_chunk) == offset
             and len(self._cached_chunk) + len(data) < _MAX_CACHED_CHUNK_SIZE
         ):
             # add to existing cache
             self._cached_chunk += data
         else:
             self._cached_chunk = data
             self._cached_chunk_position = offset