[Spice-devel] [PATCH spice-streaming-agent v2 3/5] Starts/stops the agent based on VT status

Frediano Ziglio fziglio at redhat.com
Tue May 22 11:46:48 UTC 2018


> 
> On Mon, May 21, 2018 at 11:45:29AM +0100, Frediano Ziglio wrote:
> > Check if the current display server is active or not and stream only if
> > active.
> > This will allow to support multiple display servers running.
> > When multiple display servers are running only one have the GPU
> > associated and is writing to the screen.
> > Stop capturing and release resources when the display server is not
> > active and vice versa.
> 
> Is your goal to achieve something similar to
> https://cgit.freedesktop.org/spice/linux/vd_agent/commit/?id=93003ec27d98cb47b8ea0435179a66c14ff610ce
> ?
> 
> Christophe
> 

I basically need to follow the active session on seat0 (the physical one,
like the physical display).
Usually GPU is attached to a single session and by the way we don't want
to stream all possible sessions active but just the one that is active.

> > 
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> >  src/Makefile.am               |  2 ++
> >  src/eventfd.cpp               | 38 ++++++++++++++++++++
> >  src/eventfd.hpp               | 34 ++++++++++++++++++
> >  src/spice-streaming-agent.cpp | 65 +++++++++++++++++++++++++++++++----
> >  4 files changed, 132 insertions(+), 7 deletions(-)
> >  create mode 100644 src/eventfd.cpp
> >  create mode 100644 src/eventfd.hpp
> > 
> > diff --git a/src/Makefile.am b/src/Makefile.am
> > index 276478f..ffc52b2 100644
> > --- a/src/Makefile.am
> > +++ b/src/Makefile.am
> > @@ -62,4 +62,6 @@ spice_streaming_agent_SOURCES = \
> >  	jpeg.hpp \
> >  	stream-port.cpp \
> >  	stream-port.hpp \
> > +	eventfd.cpp \
> > +	eventfd.hpp \
> >  	$(NULL)
> > diff --git a/src/eventfd.cpp b/src/eventfd.cpp
> > new file mode 100644
> > index 0000000..e3c1e72
> > --- /dev/null
> > +++ b/src/eventfd.cpp
> > @@ -0,0 +1,38 @@
> > +/* Linux event file descriptors
> > + *
> > + * \copyright
> > + * Copyright 2018 Red Hat Inc. All rights reserved.
> > + */
> > +#include <config.h>
> > +#include "eventfd.hpp"
> > +
> > +#include <stdexcept>
> > +#include <sys/eventfd.h>
> > +
> > +template<typename T>
> > +inline void ignore_result(T /* unused result */) {}
> > +
> > +namespace spice {
> > +namespace streaming_agent {
> > +
> > +EventFD::EventFD():
> > +    fd(eventfd(0, EFD_CLOEXEC|EFD_NONBLOCK))
> > +{
> > +    if (fd < 0) {
> > +        throw std::runtime_error("Failed to create eventfd");
> > +    }
> > +}
> > +
> > +void EventFD::signal()
> > +{
> > +    uint64_t n = 1;
> > +    ignore_result(write(fd, &n, sizeof(n)));
> > +}
> > +
> > +void EventFD::ack()
> > +{
> > +    uint64_t n;
> > +    ignore_result(read(fd, &n, sizeof(n)));
> > +}
> > +
> > +}} // namespace spice::streaming_agent
> > diff --git a/src/eventfd.hpp b/src/eventfd.hpp
> > new file mode 100644
> > index 0000000..48a175c
> > --- /dev/null
> > +++ b/src/eventfd.hpp
> > @@ -0,0 +1,34 @@
> > +/* Linux event file descriptors
> > + *
> > + * \copyright
> > + * Copyright 2018 Red Hat Inc. All rights reserved.
> > + */
> > +#ifndef SPICE_STREAMING_AGENT_EVENTFD_HPP
> > +#define SPICE_STREAMING_AGENT_EVENTFD_HPP
> > +
> > +#include <unistd.h>
> > +
> > +namespace spice {
> > +namespace streaming_agent {
> > +
> > +class EventFD {
> > +public:
> > +    EventFD();
> > +    ~EventFD() { close(fd); }
> > +    void signal();
> > +    void ack();
> > +    /**
> > +     * Returns underlying file descriptor.
> > +     * Do not close, should just be used for polling.
> > +     */
> > +    int raw_fd() const { return fd; }
> > +private:
> > +    EventFD(const EventFD&) = delete;
> > +    void operator=(const EventFD&) = delete;
> > +
> > +    int fd;
> > +};
> > +
> > +}} // namespace spice::streaming_agent
> > +
> > +#endif // SPICE_STREAMING_AGENT_EVENTFD_HPP
> > diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
> > index 6388bb2..240b9c7 100644
> > --- a/src/spice-streaming-agent.cpp
> > +++ b/src/spice-streaming-agent.cpp
> > @@ -10,6 +10,7 @@
> >  #include "stream-port.hpp"
> >  #include "error.hpp"
> >  #include "xorg-utils.hpp"
> > +#include "eventfd.hpp"
> >  
> >  #include <spice/stream-device.h>
> >  #include <spice/enums.h>
> > @@ -36,6 +37,7 @@
> >  #include <thread>
> >  #include <vector>
> >  #include <string>
> > +#include <atomic>
> >  #include <functional>
> >  #include <X11/Xlib.h>
> >  #include <X11/extensions/Xfixes.h>
> > @@ -61,12 +63,21 @@ static bool quit_requested = false;
> >  static bool log_binary = false;
> >  static bool log_frames = false;
> >  static std::set<SpiceVideoCodecType> client_codecs;
> > +static EventFD update_fd;
> > +static const char vt_property_name[] = "XFree86_has_VT";
> > +static const char *stream_port_name =
> > "/dev/virtio-ports/org.spice-space.stream.0";
> > +static Atom vt_property = None;
> > +static std::atomic_bool vt_active;
> >  
> > -static bool have_something_to_read(StreamPort &stream_port, bool blocking)
> > +static bool have_something_to_read(StreamPort &stream_port, bool blocking,
> > int &fd)
> >  {
> > -    struct pollfd pollfd = {stream_port.fd, POLLIN, 0};
> > +    struct pollfd pollfds[2] = {
> > +        { stream_port.fd, POLLIN, 0 },
> > +        { update_fd.raw_fd(), POLLIN, 0 },
> > +    };
> >  
> > -    if (poll(&pollfd, 1, blocking ? -1 : 0) < 0) {
> > +    fd = -1;
> > +    if (poll(pollfds, 2, blocking ? -1 : 0) < 0) {
> >          if (errno == EINTR) {
> >              // report nothing to read, next iteration of the enclosing
> >              loop will retry
> >              return false;
> > @@ -75,7 +86,13 @@ static bool have_something_to_read(StreamPort
> > &stream_port, bool blocking)
> >          throw IOError("poll failed on the device", errno);
> >      }
> >  
> > -    if (pollfd.revents & POLLIN) {
> > +    if (pollfds[1].revents & POLLIN) {
> > +        fd = update_fd.raw_fd();
> > +        return true;
> > +    }
> > +
> > +    if (pollfds[0].revents & POLLIN) {
> > +        fd = stream_port.fd;
> >          return true;
> >      }
> >  
> > @@ -173,8 +190,18 @@ static void read_command_from_device(StreamPort
> > &stream_port)
> >  static void read_command(StreamPort &stream_port, bool blocking)
> >  {
> >      while (!quit_requested) {
> > -        if (have_something_to_read(stream_port, blocking)) {
> > -            read_command_from_device(stream_port);
> > +        int fd;
> > +        if (have_something_to_read(stream_port, blocking, fd)) {
> > +            if (fd == stream_port.fd) {
> > +                read_command_from_device(stream_port);
> > +            } else if (fd == update_fd.raw_fd()) {
> > +                update_fd.ack();
> > +                bool vt_active =
> > ::vt_active.load(std::memory_order_relaxed);
> > +                if (!vt_active) {
> > +                    throw std::runtime_error("VT disabled");
> > +                }
> > +                continue;
> > +            }
> >              break;
> >          }
> >  
> > @@ -305,10 +332,22 @@ send_cursor(StreamPort &stream_port, unsigned width,
> > unsigned height, int hotspo
> >  static void cursor_changes(StreamPort *stream_port, Display *display, int
> >  event_base)
> >  {
> >      unsigned long last_serial = 0;
> > +    Window rootwindow = DefaultRootWindow(display);
> >  
> >      while (1) {
> >          XEvent event;
> >          XNextEvent(display, &event);
> > +
> > +        if (event.type == PropertyNotify) {
> > +            if (vt_property == None || event.xproperty.atom !=
> > vt_property)
> > +                continue;
> > +            // update vt property, activate screen read if needed
> > +            vt_active.store(get_win_prop_int(display, rootwindow,
> > vt_property) != 0, std::memory_order_relaxed);
> > +            std::atomic_thread_fence(std::memory_order_acquire);
> > +            update_fd.signal();
> > +            continue;
> > +        }
> > +
> >          if (event.type != event_base + 1) {
> >              continue;
> >          }
> > @@ -416,7 +455,6 @@ do_capture(StreamPort &stream_port, FILE *f_log)
> >  
> >  int main(int argc, char* argv[])
> >  {
> > -    const char *stream_port_name =
> > "/dev/virtio-ports/org.spice-space.stream.0";
> >      int opt;
> >      const char *log_filename = NULL;
> >      int logmask = LOG_UPTO(LOG_WARNING);
> > @@ -522,6 +560,19 @@ int main(int argc, char* argv[])
> >      Window rootwindow = DefaultRootWindow(display);
> >      XFixesSelectCursorInput(display, rootwindow,
> >      XFixesDisplayCursorNotifyMask);
> >  
> > +    vt_property = XInternAtom(display, vt_property_name, True);
> > +    if (vt_property == None) {
> > +        syslog(LOG_ERR, "VT property not found\n");
> > +        return EXIT_FAILURE;
> > +    }
> > +    XSelectInput(display, rootwindow, PropertyChangeMask);
> > +
> > +    vt_active.store(get_win_prop_int(display, rootwindow, vt_property) !=
> > 0, std::memory_order_relaxed);
> > +    if (!::vt_active.load(std::memory_order_relaxed)) {
> > +        syslog(LOG_ERR, "VT is disabled");
> > +        return EXIT_FAILURE;
> > +    }
> > +
> >      int ret = EXIT_SUCCESS;
> >  
> >      try {

Frediano


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