Commit f3926945 authored by Fam Zheng's avatar Fam Zheng Committed by Paolo Bonzini
Browse files

iohandler: Use aio API 



iohandler.c shares the same interface with aio, but with duplicated
code. It's better to rebase iohandler, also because that aio is a
more friendly interface to multi-threads.

Create a global AioContext instance and let its GSource handle the
iohandler events.

Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Message-Id: <1441596538-4412-1-git-send-email-famz@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 46036b24

include/qemu/main-loop.h

+1 −2
Original line number Diff line number Diff line
@@ -203,6 +203,7 @@ void qemu_set_fd_handler(int fd, 
                         IOHandler *fd_write,

                         void *opaque);



GSource *iohandler_get_g_source(void);

#ifdef CONFIG_POSIX

/**

 * qemu_add_child_watch: Register a child process for reaping.
@@ -265,8 +266,6 @@ 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);

iohandler.c

+15 −96
Original line number Diff line number Diff line
@@ -32,111 +32,30 @@ 
#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);

/* This context runs on top of main loop. We can't reuse qemu_aio_context

 * because iohandlers mustn't be polled by aio_poll(qemu_aio_context). */

static AioContext *iohandler_ctx;



void qemu_set_fd_handler(int fd,

                         IOHandler *fd_read,

                         IOHandler *fd_write,

                         void *opaque)

static void iohandler_init(void)

{

    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();

    if (!iohandler_ctx) {

        iohandler_ctx = aio_context_new(&error_abort);

    }

}



void qemu_iohandler_fill(GArray *pollfds)

GSource *iohandler_get_g_source(void)

{

    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;

        }

    }

    iohandler_init();

    return aio_get_g_source(iohandler_ctx);

}



void qemu_iohandler_poll(GArray *pollfds, int ret)

void qemu_set_fd_handler(int fd,

                         IOHandler *fd_read,

                         IOHandler *fd_write,

                         void *opaque)

{

    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);

            }

        }

    }

    iohandler_init();

    aio_set_fd_handler(iohandler_ctx, fd, fd_read, fd_write, opaque);

}



/* reaping of zombies.  right now we're not passing the status to

main-loop.c

+3 −2
Original line number Diff line number Diff line
@@ -161,6 +161,9 @@ int qemu_init_main_loop(Error **errp) 
    src = aio_get_g_source(qemu_aio_context);

    g_source_attach(src, NULL);

    g_source_unref(src);

    src = iohandler_get_g_source();

    g_source_attach(src, NULL);

    g_source_unref(src);

    return 0;

}
@@ -487,7 +490,6 @@ 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;
@@ -500,7 +502,6 @@ 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