[Python-checkins] bpo-35589: Prevent buffer copy in sock_sendall() (GH-11418)

Thu May 16 09:30:23 EDT 2019

https://github.com/python/cpython/commit/6e7890028213b30939327e7cf885bf097fc14472
commit: 6e7890028213b30939327e7cf885bf097fc14472
branch: master
author: Andrew Svetlov <andrew.svetlov at gmail.com>
committer: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
date: 2019年05月16日T06:30:16-07:00
summary:
bpo-35589: Prevent buffer copy in sock_sendall() (GH-11418)
No NEWs is needed since the problem was introduced on master only and never released.
https://bugs.python.org/issue35589
files:
M Lib/asyncio/selector_events.py

diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
index 29968214f8ed..6461d3077633 100644
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -428,32 +428,35 @@ def _sock_recv_into(self, fut, sock, buf):
 if n == len(data):
 # all data sent
 return
- else:
- data = bytearray(memoryview(data)[n:])
 
 fut = self.create_future()
 fd = sock.fileno()
 fut.add_done_callback(
 functools.partial(self._sock_write_done, fd))
- self.add_writer(fd, self._sock_sendall, fut, sock, data)
+ # use a trick with a list in closure to store a mutable state
+ self.add_writer(fd, self._sock_sendall, fut, sock,
+ memoryview(data), [n])
 return await fut
 
- def _sock_sendall(self, fut, sock, data):
+ def _sock_sendall(self, fut, sock, view, pos):
 if fut.done():
 # Future cancellation can be scheduled on previous loop iteration
 return
+ start = pos[0]
 try:
- n = sock.send(data)
+ n = sock.send(view[start:])
 except (BlockingIOError, InterruptedError):
 return
 except Exception as exc:
 fut.set_exception(exc)
 return
 
- if n == len(data):
+ start += n
+
+ if start == len(view):
 fut.set_result(None)
 else:
- del data[:n]
+ pos[0] = start
 
 async def sock_connect(self, sock, address):
 """Connect to a remote socket at address.
