On Mon, Jan 16, 2017 at 07:38:24PM +0800, Fam Zheng wrote:
> On Fri, 01/13 14:17, Paolo Bonzini wrote:
> > Support separate coroutines for reading and writing, and place the
> > read/write handlers on the AioContext that the QIOChannel is registered
> > with.
> >
> > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> > ---
> > include/io/channel.h | 37 ++++++++++++++++++----
> > io/channel.c | 86
> > ++++++++++++++++++++++++++++++++++++++------------
> > tests/Makefile.include | 2 +-
> > 3 files changed, 96 insertions(+), 29 deletions(-)
> >
> > diff --git a/include/io/channel.h b/include/io/channel.h
> > index 665edd7..d7bad94 100644
> > --- a/include/io/channel.h
> > +++ b/include/io/channel.h
> > @@ -23,6 +23,7 @@
> >
> > #include "qemu-common.h"
> > #include "qom/object.h"
> > +#include "qemu/coroutine.h"
> > #include "block/aio.h"
> >
> > #define TYPE_QIO_CHANNEL "qio-channel"
> > @@ -59,8 +60,6 @@ typedef gboolean (*QIOChannelFunc)(QIOChannel *ioc,
> > GIOCondition condition,
> > gpointer data);
> >
> > -typedef struct QIOChannelRestart QIOChannelRestart;
> > -
> > /**
> > * QIOChannel:
> > *
> > @@ -84,8 +83,8 @@ struct QIOChannel {
> > unsigned int features; /* bitmask of QIOChannelFeatures */
> > char *name;
> > AioContext *ctx;
> > - QIOChannelRestart *read_coroutine;
> > - QIOChannelRestart *write_coroutine;
> > + Coroutine *read_coroutine;
> > + Coroutine *write_coroutine;
> > #ifdef _WIN32
> > HANDLE event; /* For use with GSource on Win32 */
> > #endif
> > @@ -508,13 +507,37 @@ guint qio_channel_add_watch(QIOChannel *ioc,
> >
> >
> > /**
> > + * qio_channel_set_aio_context:
> > + * @ioc: the channel object
> > + * @ctx: the #AioContext to set the handlers on
> > + *
> > + * Request that qio_channel_yield() sets I/O handlers on
> > + * the given #AioContext. If @ctx is %NULL, qio_channel_yield()
> > + * uses QEMU's main thread event loop.
> > + */
> > +void qio_channel_set_aio_context(QIOChannel *ioc,
> > + AioContext *ctx);
> > +
> > +/**
> > + * qio_channel_detach_aio_context:
> > + * @ioc: the channel object
> > + *
> > + * Disable any I/O handlers set by qio_channel_yield(). With the
> > + * help of aio_co_schedule(), this allows moving a coroutine that was
> > + * paused by qio_channel_yield() to another context.
> > + */
> > +void qio_channel_detach_aio_context(QIOChannel *ioc);
> > +
> > +/**
> > * qio_channel_yield:
> > * @ioc: the channel object
> > * @condition: the I/O condition to wait for
> > *
> > - * Yields execution from the current coroutine until
> > - * the condition indicated by @condition becomes
> > - * available.
> > + * Yields execution from the current coroutine until the condition
> > + * indicated by @condition becomes available. @condition must
> > + * be either %G_IO_IN or %G_IO_OUT; it cannot contain both. In
> > + * addition, no two coroutine can be waiting on the same condition
> > + * and channel at the same time.
> > *
> > * This must only be called from coroutine context
> > */
> > diff --git a/io/channel.c b/io/channel.c
> > index ce470d7..1e043bf 100644
> > --- a/io/channel.c
> > +++ b/io/channel.c
> > @@ -21,7 +21,7 @@
> > #include "qemu/osdep.h"
> > #include "io/channel.h"
> > #include "qapi/error.h"
> > -#include "qemu/coroutine.h"
> > +#include "qemu/main-loop.h"
> >
> > bool qio_channel_has_feature(QIOChannel *ioc,
> > QIOChannelFeature feature)
> > @@ -238,36 +238,80 @@ off_t qio_channel_io_seek(QIOChannel *ioc,
> > }
> >
> >
> > -typedef struct QIOChannelYieldData QIOChannelYieldData;
> > -struct QIOChannelYieldData {
> > - QIOChannel *ioc;
> > - Coroutine *co;
> > -};
> > +static void qio_channel_set_aio_fd_handlers(QIOChannel *ioc);
> > +
> > +static void qio_channel_restart_read(void *opaque)
> > +{
> > + QIOChannel *ioc = opaque;
> > + Coroutine *co = ioc->read_coroutine;
> >
> > + ioc->read_coroutine = NULL;
> > + qio_channel_set_aio_fd_handlers(ioc);
> > + aio_co_wake(co);
> > +}
> >
> > -static gboolean qio_channel_yield_enter(QIOChannel *ioc,
> > - GIOCondition condition,
> > - gpointer opaque)
> > +static void qio_channel_restart_write(void *opaque)
> > {
> > - QIOChannelYieldData *data = opaque;
> > - qemu_coroutine_enter(data->co);
> > - return FALSE;
> > + QIOChannel *ioc = opaque;
> > + Coroutine *co = ioc->write_coroutine;
> > +
> > + ioc->write_coroutine = NULL;
> > + qio_channel_set_aio_fd_handlers(ioc);
> > + aio_co_wake(co);
> > }
> >
> > +static void qio_channel_set_aio_fd_handlers(QIOChannel *ioc)
> > +{
> > + IOHandler *rd_handler = NULL, *wr_handler = NULL;
> > + AioContext *ctx;
> > +
> > + if (ioc->read_coroutine) {
> > + rd_handler = qio_channel_restart_read;
>
> s/\t/ /
>
> > + }
> > + if (ioc->write_coroutine) {
> > + rd_handler = qio_channel_restart_write;
>
> s/\t/ /
>
> > + }
> > +
> > + ctx = ioc->ctx ? ioc->ctx : iohandler_get_aio_context();
> > + qio_channel_set_aio_fd_handler(ioc, ctx, rd_handler, wr_handler, ioc);
> > +}
> > +
> > +void qio_channel_set_aio_context(QIOChannel *ioc,
> > + AioContext *ctx)
> > +{
> > + AioContext *old_ctx;
> > + if (ioc->ctx == ctx) {
> > + return;
> > + }
> > +
> > + old_ctx = ioc->ctx ? ioc->ctx : iohandler_get_aio_context();
> > + qio_channel_set_aio_fd_handler(ioc, old_ctx, NULL, NULL, NULL);
> > + ioc->ctx = ctx;
> > + qio_channel_set_aio_fd_handlers(ioc);
> > +}
> > +
> > +void qio_channel_detach_aio_context(QIOChannel *ioc)
> > +{
> > + ioc->read_coroutine = NULL;
> > + ioc->write_coroutine = NULL;
> > + qio_channel_set_aio_fd_handlers(ioc);
>
> Why is qio_channel_set_aio_fd_handler not needed here?
>
> > + ioc->ctx = NULL;
> > +}
> >
> > void coroutine_fn qio_channel_yield(QIOChannel *ioc,
> > GIOCondition condition)
> > {
> > - QIOChannelYieldData data;
> > -
> > assert(qemu_in_coroutine());
> > - data.ioc = ioc;
> > - data.co = qemu_coroutine_self();
> > - qio_channel_add_watch(ioc,
> > - condition,
> > - qio_channel_yield_enter,
> > - &data,
> > - NULL);
> > + if (condition == G_IO_IN) {
> > + assert(!ioc->read_coroutine);
> > + ioc->read_coroutine = qemu_coroutine_self();
> > + } else if (condition == G_IO_OUT) {
> > + assert(!ioc->write_coroutine);
> > + ioc->write_coroutine = qemu_coroutine_self();
> > + } else {
> > + abort();
> > + }
> > + qio_channel_set_aio_fd_handlers(ioc);
> > qemu_coroutine_yield();
> > }
> >
> > diff --git a/tests/Makefile.include b/tests/Makefile.include
> > index 3b8ed9d..7d11bbb 100644
> > --- a/tests/Makefile.include
> > +++ b/tests/Makefile.include
> > @@ -493,7 +493,7 @@ tests/check-qjson$(EXESUF): tests/check-qjson.o
> > $(test-util-obj-y)
> > tests/check-qom-interface$(EXESUF): tests/check-qom-interface.o
> > $(test-qom-obj-y)
> > tests/check-qom-proplist$(EXESUF): tests/check-qom-proplist.o
> > $(test-qom-obj-y)
> >
> > -tests/test-char$(EXESUF): tests/test-char.o qemu-char.o qemu-timer.o
> > $(test-util-obj-y) $(qtest-obj-y) $(test-io-obj-y)
> > +tests/test-char$(EXESUF): tests/test-char.o qemu-char.o qemu-timer.o
> > $(test-util-obj-y) $(qtest-obj-y) $(test-io-obj-y) $(test-block-obj-y)
>
> I guess this is a hint for moving coroutine code into a lower level library
> like
> util.
The coroutine code is already in util/, so I'm assuming this is actually
for the AioContext stuff. Yes, though, AioContext ought to be moved into
util/ as part of this series IMHO, since the io/ channel code shouldn't
have a dependancy on block/ layer.
Regards,
Daniel
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