akira added the comment:
use_fallback parameter is mostly a debugging tool. If it helps to avoid the
indecision; I would side with neologix' remarks and also suggest to drop
the use_fallback parameter.
It seems the patch assumes *offset == nbytes_sent* that is false in general
e.g., if offset > 0 at the start of the function.
::
_SEND_BLOCKSIZE = 262144 # ???
def sendfile(self, file, offset=None, nbytes=None,
*, nbytes_per_send=_SEND_BLOCKSIZE) -> nbytes_sent:
"""
Send *nbytes* bytes from regular *file* starting at *offset* position.
Return the number of bytes sent.
If *offset* is ``None``; start at the current file position.
If *nbytes* is ``None``; send file until EOF is reached.
The socket should be connection-oriented e.g., SOCK_STREAM
*nbytes_per_send* is used by a *send()*-based fallback code.
*os.sendfile()* ignores it.
- if socket is blocking (timeout is None) then it may keep
trying to send data until an error occurs.
Even on success it may return less than *nbytes* if there is
not enough data available in *file*.
- if socket is non-blocking and timeout == 0 then fail if
even a single byte can't be sent immediately
- if socket has timeout > 0 then raise the timeout error if
more than *timeout* seconds pass since the call is started
and nothing is sent i.e., use a single deadline for all
system calls (like *socket.send()*).
If timeout is not None then *socket.sendfile()* may send less
bytes than specified.
*file* position after the call is unspecified.
"""
# pseudo-code
total = 0
if offset is None
offset = file.tell()
if nbytes is None:
nbytes = os.path.getsize(file.name)
interval = self.timeout
if interval is not None:
deadline = now() + interval
while select([], [self], [], interval)[1]: # writable
try:
sent = os.sendfile(self, file, offset, nbytes)
except BlockingIOError as e:
assert getattr(e, 'characters_written', 0) == 0
if interval is not None: # update interval
interval = deadline - now()
if interval < 0:
break
continue # ignore
else:
if sent == 0:
return total
total += sent
offset += sent
nbytes -= sent
if nbytes == 0:
return total
if interval is not None: # update interval
interval = deadline - now()
if interval < 0:
break
# timeout
if total == 0:
raise TimeoutError
else:
return total
----------
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue17552>
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