diff options
Diffstat (limited to 'Lib/_pyio.py')
| -rw-r--r-- | Lib/_pyio.py | 37 |
1 files changed, 23 insertions, 14 deletions
diff --git a/Lib/_pyio.py b/Lib/_pyio.py index b3a8f37..f7370df 100644 --- a/Lib/_pyio.py +++ b/Lib/_pyio.py @@ -1454,6 +1454,17 @@ class BufferedRandom(BufferedWriter, BufferedReader): return BufferedWriter.write(self, b) +def _new_buffersize(bytes_read): + # Parallels _io/fileio.c new_buffersize + if bytes_read > 65536: + addend = bytes_read >> 3 + else: + addend = 256 + bytes_read + if addend < DEFAULT_BUFFER_SIZE: + addend = DEFAULT_BUFFER_SIZE + return bytes_read + addend + + class FileIO(RawIOBase): _fd = -1 _created = False @@ -1672,22 +1683,20 @@ class FileIO(RawIOBase): except OSError: pass - result = bytearray() - while True: - if len(result) >= bufsize: - bufsize = len(result) - bufsize += max(bufsize, DEFAULT_BUFFER_SIZE) - n = bufsize - len(result) - try: - chunk = os.read(self._fd, n) - except BlockingIOError: - if result: - break + result = bytearray(bufsize) + bytes_read = 0 + try: + while n := os.readinto(self._fd, memoryview(result)[bytes_read:]): + bytes_read += n + if bytes_read >= len(result): + result.resize(_new_buffersize(bytes_read)) + except BlockingIOError: + if not bytes_read: return None - if not chunk: # reached the end of the file - break - result += chunk + assert len(result) - bytes_read >= 1, \ + "os.readinto buffer size 0 will result in erroneous EOF / returns 0" + result.resize(bytes_read) return bytes(result) def readinto(self, buffer): |