[Qemu-devel] [RFC PATCH v2 13/13] iohandler: Use AioContext internally

[Fam Zheng <famz@redhat.com>]

AioContext and iohandler share the same concept except that AioContext
is more generalized - it runs on an AioContext which could be on the
main thread or an iothread. Similar to the relation of qemu_bh_new and
aio_bh_new, the iohandler is the special case of AioContext which
happens to run on the main thread context.

Previously the only mismatch is the presense of qemu_set_fd_handler2
with the special "can_read" parameter which is not available in
AioContext interface, now the parameter is removed, let's unify the code
and make iohandler a wrapper. Meanwhile, change the function's return
type to void because it always returns 0.

This also simplifies the main loop by removing the qemu_iohandler_fill
and qemu_iohandler_poll hooks.

One tiny things is this also makes sigfd depends on the main loop
AioContext, so we have to move the call of qemu_signal_init() in after
creation of qemu_aio_context.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 include/qemu/main-loop.h |  10 ++---
 iohandler.c              | 110 -----------------------------------------------
 main-loop.c              |  21 ++++++---
 stubs/set-fd-handler.c   |   8 ++--
 4 files changed, 22 insertions(+), 127 deletions(-)

diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index 7da1d63..ef87d1c 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -198,10 +198,10 @@ typedef int IOCanReadHandler(void *opaque);
  *
  * @opaque: A pointer-sized value that is passed to @fd_read and @fd_write.
  */
-int qemu_set_fd_handler(int fd,
-                        IOHandler *fd_read,
-                        IOHandler *fd_write,
-                        void *opaque);
+void qemu_set_fd_handler(int fd,
+                         IOHandler *fd_read,
+                         IOHandler *fd_write,
+                         void *opaque);
 
 #ifdef CONFIG_POSIX
 /**
@@ -255,8 +255,6 @@ void qemu_mutex_unlock_iothread(void);
 /* internal interfaces */
 
 void qemu_fd_register(int fd);
-void qemu_iohandler_fill(GArray *pollfds);
-void qemu_iohandler_poll(GArray *pollfds, int rc);
 
 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque);
 void qemu_bh_schedule_idle(QEMUBH *bh);
diff --git a/iohandler.c b/iohandler.c
index d361cf2..c7f4d01 100644
--- a/iohandler.c
+++ b/iohandler.c
@@ -24,122 +24,12 @@
 
 #include "config-host.h"
 #include "qemu-common.h"
-#include "qemu/queue.h"
-#include "block/aio.h"
 #include "qemu/main-loop.h"
 
 #ifndef _WIN32
 #include <sys/wait.h>
 #endif
 
-typedef struct IOHandlerRecord {
-    IOHandler *fd_read;
-    IOHandler *fd_write;
-    void *opaque;
-    QLIST_ENTRY(IOHandlerRecord) next;
-    int fd;
-    int pollfds_idx;
-    bool deleted;
-} IOHandlerRecord;
-
-static QLIST_HEAD(, IOHandlerRecord) io_handlers =
-    QLIST_HEAD_INITIALIZER(io_handlers);
-
-int qemu_set_fd_handler(int fd,
-                        IOHandler *fd_read,
-                        IOHandler *fd_write,
-                        void *opaque)
-{
-    IOHandlerRecord *ioh;
-
-    assert(fd >= 0);
-
-    if (!fd_read && !fd_write) {
-        QLIST_FOREACH(ioh, &io_handlers, next) {
-            if (ioh->fd == fd) {
-                ioh->deleted = 1;
-                break;
-            }
-        }
-    } else {
-        QLIST_FOREACH(ioh, &io_handlers, next) {
-            if (ioh->fd == fd)
-                goto found;
-        }
-        ioh = g_malloc0(sizeof(IOHandlerRecord));
-        QLIST_INSERT_HEAD(&io_handlers, ioh, next);
-    found:
-        ioh->fd = fd;
-        ioh->fd_read = fd_read;
-        ioh->fd_write = fd_write;
-        ioh->opaque = opaque;
-        ioh->pollfds_idx = -1;
-        ioh->deleted = 0;
-        qemu_notify_event();
-    }
-    return 0;
-}
-
-void qemu_iohandler_fill(GArray *pollfds)
-{
-    IOHandlerRecord *ioh;
-
-    QLIST_FOREACH(ioh, &io_handlers, next) {
-        int events = 0;
-
-        if (ioh->deleted)
-            continue;
-        if (ioh->fd_read) {
-            events |= G_IO_IN | G_IO_HUP | G_IO_ERR;
-        }
-        if (ioh->fd_write) {
-            events |= G_IO_OUT | G_IO_ERR;
-        }
-        if (events) {
-            GPollFD pfd = {
-                .fd = ioh->fd,
-                .events = events,
-            };
-            ioh->pollfds_idx = pollfds->len;
-            g_array_append_val(pollfds, pfd);
-        } else {
-            ioh->pollfds_idx = -1;
-        }
-    }
-}
-
-void qemu_iohandler_poll(GArray *pollfds, int ret)
-{
-    if (ret > 0) {
-        IOHandlerRecord *pioh, *ioh;
-
-        QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
-            int revents = 0;
-
-            if (!ioh->deleted && ioh->pollfds_idx != -1) {
-                GPollFD *pfd = &g_array_index(pollfds, GPollFD,
-                                              ioh->pollfds_idx);
-                revents = pfd->revents;
-            }
-
-            if (!ioh->deleted && ioh->fd_read &&
-                (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR))) {
-                ioh->fd_read(ioh->opaque);
-            }
-            if (!ioh->deleted && ioh->fd_write &&
-                (revents & (G_IO_OUT | G_IO_ERR))) {
-                ioh->fd_write(ioh->opaque);
-            }
-
-            /* Do this last in case read/write handlers marked it for deletion */
-            if (ioh->deleted) {
-                QLIST_REMOVE(ioh, next);
-                g_free(ioh);
-            }
-        }
-    }
-}
-
 /* reaping of zombies.  right now we're not passing the status to
    anyone, but it would be possible to add a callback.  */
 #ifndef _WIN32
diff --git a/main-loop.c b/main-loop.c
index 82875a4..20776f9 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -138,16 +138,17 @@ int qemu_init_main_loop(Error **errp)
 
     init_clocks();
 
-    ret = qemu_signal_init();
-    if (ret) {
-        return ret;
-    }
-
     qemu_aio_context = aio_context_new(&local_error);
     if (!qemu_aio_context) {
         error_propagate(errp, local_error);
         return -EMFILE;
     }
+
+    ret = qemu_signal_init();
+    if (ret) {
+        return ret;
+    }
+
     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
     src = aio_get_g_source(qemu_aio_context);
     g_source_attach(src, NULL);
@@ -478,7 +479,6 @@ int main_loop_wait(int nonblocking)
 #ifdef CONFIG_SLIRP
     slirp_pollfds_fill(gpollfds, &timeout);
 #endif
-    qemu_iohandler_fill(gpollfds);
 
     if (timeout == UINT32_MAX) {
         timeout_ns = -1;
@@ -491,7 +491,6 @@ int main_loop_wait(int nonblocking)
                                           &main_loop_tlg));
 
     ret = os_host_main_loop_wait(timeout_ns);
-    qemu_iohandler_poll(gpollfds, ret);
 #ifdef CONFIG_SLIRP
     slirp_pollfds_poll(gpollfds, (ret < 0));
 #endif
@@ -507,3 +506,11 @@ QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
 {
     return aio_bh_new(qemu_aio_context, cb, opaque);
 }
+
+void qemu_set_fd_handler(int fd,
+                        IOHandler *fd_read,
+                        IOHandler *fd_write,
+                        void *opaque)
+{
+    aio_set_fd_handler(qemu_aio_context, fd, fd_read, fd_write, opaque);
+}
diff --git a/stubs/set-fd-handler.c b/stubs/set-fd-handler.c
index a895e62..a8481bc 100644
--- a/stubs/set-fd-handler.c
+++ b/stubs/set-fd-handler.c
@@ -1,10 +1,10 @@
 #include "qemu-common.h"
 #include "qemu/main-loop.h"
 
-int qemu_set_fd_handler(int fd,
-                        IOHandler *fd_read,
-                        IOHandler *fd_write,
-                        void *opaque)
+void qemu_set_fd_handler(int fd,
+                         IOHandler *fd_read,
+                         IOHandler *fd_write,
+                         void *opaque)
 {
     abort();
 }
-- 
2.4.0