They can fail, when the recognition session outlives the test
function, which is expected to happen, as the session is concurrent.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53458
`length` for localStorage is not updated immediately on native, which
suggests some caching is involved for a period of time (probably for
performance reasons to avoid reading the file everytime the prop is read),
or it doesn't block like the rest since the write is asynchronous, making
it unreliable to test, which is why the tests for it are basic.
Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com>
foobar2000.exe's UPnP Media Renderer component (foo_out_upnp.dll)
expects that, if a select() call completes successfully with a non-empty
writefds set, any immediately following send() call on a socket in the
writefds set never fails with WSAEWOULDBLOCK.
On Wine, the Winsock select() and send() implementations both call the
Unix poll(2) under the hood to test if I/O is possible on the socket.
As it turns out, it's entirely possible that Linux poll() may yield
POLLOUT on the first call (by select) but *not* the second (by send),
even if no send() call has been made in the meanwhile.
On Linux (as of v5.19), a connected (ESTABLISHED) TCP socket that has
not been shut down indicates (E)POLLOUT only if the ratio of
sk_wmem_queued (the amount of bytes queued in the send buffer) to
sk_sndbuf (the size of send buffer size itself, which can be retrieved
via SO_SNDBUF) is below a certain threshold. Therefore, a falling edge
in POLLOUT can be triggered due to a number of reasons:
1. TCP fragmentation. Once a TCP packet is split out from a larger
sk_buff, it incurs extra bookkeeping overhead (e.g. sk_buff header)
that is counted in sk_wmem_queued alongside application data.
See also: tcp_fragment(), tso_fragment() (Linux 5.19).
2. Control packets (e.g. MTU probing). Such packets share the same
buffer with application-initiated packets, and thus counted in
sk_wmem_queued.
See also: sk_wmem_queued_add() callers (Linux 5.19).
3. Memory pressure. This causes sk_sndbuf to shrink.
See also: sk_stream_moderate_sndbuf() callers (Linux 5.19).
Fix this by always attempting synchronous I/O first if req->force_async
is unset and the nonblocking flag is set.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53486
