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Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_ad
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch |
Date: |
Thu, 24 Nov 2011 18:30:32 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 |
On 11/24/2011 06:11 PM, Fabien Chouteau wrote:
Hello,
I've run into some problems with this patch on Windows. The thing is
that select() should be used only with socket file descriptors.
If glib_select_fill() put a non-socket file descriptor in rfds or wfds,
select() will fail with this error (btw the return value of select is
not checked):
This patch actually has been reverted in commit be08e65. Is it the
revert that is causing problems? If so, what is it that
glib_select_fill puts in rfds and wfds?
I've look at the patch and I don't see why do you pick file descriptors
from g_main_context_query's "poll_fds" to put them in the fd_sets (rfds,
wfds...) and then re-build a "poll_fds" to call g_main_context_check and
g_main_context_dispatch. From my understanding we can just do:
g_main_context_prepare(context,&max_priority);
n_poll_fds = g_main_context_query(context, max_priority,&timeout,
poll_fds, ARRAY_SIZE(poll_fds));
if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
g_main_context_dispatch(context);
}
Or even just call g_main_context_iteration(). What do you think?
You would have to call it in nonblocking mode from a polling handler
(qemu_add_polling_cb).
A better solution is to move the whole main loop polling into
os_host_main_loop_wait.
For POSIX, it would be just a call to
glib_select_fill+select+glib_select_poll. (Everything around these
three would stay in the caller, and the fd_sets would be passed to
os_host_main_loop_wait).
For Windows, it would work like this (and would not use glib_select_* at
all):
1) call the polling handlers;
2) call select with timeout zero. If no socket is ready, call
WSAEventSelect on the sockets listed in the fd_sets;
3) call g_main_context_prepare+query.
4) add the event from (2) and the registered wait objects to the
poll_fds. Call g_poll on it. If sockets were ready, force 0 timeout.
5) If no sockets were ready, call again select with timeout zero.
6) Check the output of g_poll and dispatch the wait objects that are now
ready.
7) Call g_main_context_check+dispatch.
Paolo
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/24
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Paolo Bonzini, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Paolo Bonzini, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Paolo Bonzini, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Paolo Bonzini, 2011/11/25
- Re: [Qemu-devel] [PATCH 2/2] main: switch qemu_set_fd_handler to g_io_add_watch, Fabien Chouteau, 2011/11/28