Use g_poll(3) instead of select(2). Well, this is kind of a cheat.
It's true that we're now using g_poll(3) on POSIX hosts but the *_fill()
and *_poll() functions are still using rfds/wfds/xfds.
We've set the scene to start converting *_fill() and *_poll() functions
step-by-step until no more rfds/wfds/xfds users remain. Then we'll drop
poller_from_select() and poller_to_select() completely and be left with
native g_poll(2).
On Windows things are a little crazy: convert from rfds/wfds/xfds to
Poller, back to rfds/wfds/xfds, call select(2), rfds/wfds/xfds back to
Poller, and finally back to rfds/wfds/xfds again. This is only
temporary and keeps the Windows build working through the following
patches. We'll drop this excessive conversion later and be left with a
single Poller -> select(2) -> Poller sequence that allows Windows to use
select(2) while the rest of QEMU only knows about Poller.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
main-loop.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 73 insertions(+), 8 deletions(-)
diff --git a/main-loop.c b/main-loop.c
index d0d8fe4..8d552d4 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -26,6 +26,7 @@
#include "qemu/timer.h"
#include "slirp/slirp.h"
#include "qemu/main-loop.h"
+#include "qemu/poller.h"
#include "block/aio.h"
#ifndef _WIN32
@@ -140,12 +141,65 @@ int qemu_init_main_loop(void)
return 0;
}
+static Poller poller;
static fd_set rfds, wfds, xfds;
static int nfds;
static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
static int n_poll_fds;
static int max_priority;
+/* Load rfds/wfds/xfds into Poller. Will be removed a few commits later. */
+static void poller_from_select(void)
+{
+ int fd;
+ for (fd = 0; fd <= nfds; fd++) {
+ int events = 0;
+ if (FD_ISSET(fd, &rfds)) {
+ events |= G_IO_IN | G_IO_HUP | G_IO_ERR;
+ }
+ if (FD_ISSET(fd, &wfds)) {
+ events |= G_IO_OUT | G_IO_ERR;
+ }
+ if (FD_ISSET(fd, &xfds)) {
+ events |= G_IO_PRI;
+ }
+ if (events) {
+ poller_add_fd(&poller, fd, events);
+ }
+ }
+}
+
+/* Store Poller revents into rfds/wfds/xfds. Will be removed a few commits
+ * later.
+ */
+static void poller_to_select(int ret)
+{
+ int i;
+
+ FD_ZERO(&rfds);
+ FD_ZERO(&wfds);
+ FD_ZERO(&xfds);
+
+ if (ret <= 0) {
+ return;
+ }
+
+ for (i = 0; i < poller.nfds; i++) {
+ int fd = poller.poll_fds[i].fd;
+ int revents = poller.poll_fds[i].revents;
+
+ if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) {
+ FD_SET(fd, &rfds);
+ }
+ if (revents & (G_IO_OUT | G_IO_ERR)) {
+ FD_SET(fd, &wfds);
+ }
+ if (revents & G_IO_PRI) {
+ FD_SET(fd, &xfds);
+ }
+ }
+}
+
#ifndef _WIN32
static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
fd_set *xfds, uint32_t *cur_timeout)
@@ -212,22 +266,22 @@ static void glib_select_poll(fd_set *rfds, fd_set *wfds,
fd_set *xfds,
static int os_host_main_loop_wait(uint32_t timeout)
{
- struct timeval tv, *tvarg = NULL;
int ret;
glib_select_fill(&nfds, &rfds, &wfds, &xfds, &timeout);
- if (timeout < UINT32_MAX) {
- tvarg = &tv;
- tv.tv_sec = timeout / 1000;
- tv.tv_usec = (timeout % 1000) * 1000;
- }
-
if (timeout > 0) {
qemu_mutex_unlock_iothread();
}
- ret = select(nfds + 1, &rfds, &wfds, &xfds, tvarg);
+ /* We'll eventually drop fd_set completely. But for now we still have
+ * *_fill() and *_poll() functions that use rfds/wfds/xfds.
+ */
+ poller_from_select();
+
+ ret = g_poll(poller.poll_fds, poller.nfds, timeout);
+
+ poller_to_select(ret);
if (timeout > 0) {
qemu_mutex_lock_iothread();
@@ -382,12 +436,22 @@ static int os_host_main_loop_wait(uint32_t timeout)
* improve socket latency.
*/
+ /* This back-and-forth between Poller and select(2) is temporary. We'll
+ * drop it in a couple of patches, I promise :).
+ */
+ poller_from_select();
+ FD_ZERO(&rfds);
+ FD_ZERO(&wfds);
+ FD_ZERO(&xfds);
+ nfds = poller_fill(&poller, &rfds, &wfds, &xfds);
if (nfds >= 0) {
select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
if (select_ret != 0) {
timeout = 0;
+ poller_poll(&poller, nfds, &rfds, &wfds, &xfds);
}
}
+ poller_to_select(select_ret || g_poll_ret);
return select_ret || g_poll_ret;
}
@@ -403,6 +467,7 @@ int main_loop_wait(int nonblocking)
}
/* poll any events */
+ poller_reset(&poller);
/* XXX: separate device handlers from system ones */
nfds = -1;
FD_ZERO(&rfds);
--
1.8.1
