diff --git a/Doc/library/asyncio-stream.rst b/Doc/library/asyncio-stream.rst index 3b3c68ab6ef..bbac1c32b56 100644 --- a/Doc/library/asyncio-stream.rst +++ b/Doc/library/asyncio-stream.rst @@ -206,12 +206,20 @@ StreamReader .. coroutinemethod:: read(n=-1) - Read up to *n* bytes. If *n* is not provided, or set to ``-1``, - read until EOF and return all read bytes. + Read up to *n* bytes from the stream. + If *n* is not provided or set to ``-1``, + read until EOF, then return all read :class:`bytes`. If EOF was received and the internal buffer is empty, return an empty ``bytes`` object. + If *n* is ``0``, return an empty ``bytes`` object immediately. + + If *n* is positive, return at most *n* available ``bytes`` + as soon as at least 1 byte is available in the internal buffer. + If EOF is received before any byte is read, return an empty + ``bytes`` object. + .. coroutinemethod:: readline() Read one line, where "line" is a sequence of bytes diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py index 7d13e961bd2..bf15f517e50 100644 --- a/Lib/asyncio/streams.py +++ b/Lib/asyncio/streams.py @@ -649,16 +649,17 @@ class StreamReader: async def read(self, n=-1): """Read up to `n` bytes from the stream. - If n is not provided, or set to -1, read until EOF and return all read - bytes. If the EOF was received and the internal buffer is empty, return - an empty bytes object. + If `n` is not provided or set to -1, + read until EOF, then return all read bytes. + If EOF was received and the internal buffer is empty, + return an empty bytes object. - If n is zero, return empty bytes object immediately. + If `n` is 0, return an empty bytes object immediately. - If n is positive, this function try to read `n` bytes, and may return - less or equal bytes than requested, but at least one byte. If EOF was - received before any byte is read, this function returns empty byte - object. + If `n` is positive, return at most `n` available bytes + as soon as at least 1 byte is available in the internal buffer. + If EOF is received before any byte is read, return an empty + bytes object. Returned value is not limited with limit, configured at stream creation.