[Spice-devel] [PATCH 13/22] Convert message writing from C style to C++ style
Lukáš Hrázký
lhrazky at redhat.com
Thu Mar 1 13:45:20 UTC 2018
On Wed, 2018-02-28 at 16:43 +0100, Christophe de Dinechin wrote:
> From: Christophe de Dinechin <dinechin at redhat.com>
>
> - The Stream class now deals with locking and sending messages
> - The Message<> template class deals with the general writing mechanisms
> - Classes, FormatMessage, FrameMessage, CapabilitiesMessage and
> X11CursorMessage represent individual messages
>
> The various classes should be moved to separate headers in a
> subsequent operation
>
> The design uses the "curiously recurring template pattern" (CRTP) to
> defer some of the code to a derived class. This is done to avoid
> runtime overhead: all the calls are static.
>
> Signed-off-by: Christophe de Dinechin <dinechin at redhat.com>
> ---
> src/spice-streaming-agent.cpp | 279 +++++++++++++++++++-----------------------
> 1 file changed, 128 insertions(+), 151 deletions(-)
>
> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
> index 23ee824..8bbd457 100644
> --- a/src/spice-streaming-agent.cpp
> +++ b/src/spice-streaming-agent.cpp
> @@ -48,24 +48,6 @@ namespace spice
> namespace streaming_agent
> {
>
> -struct FormatMessage
> -{
> - StreamDevHeader hdr;
> - StreamMsgFormat msg;
> -};
> -
> -struct DataMessage
> -{
> - StreamDevHeader hdr;
> - StreamMsgData msg;
> -};
> -
> -struct CursorMessage
> -{
> - StreamDevHeader hdr;
> - StreamMsgCursorSet msg;
> -};
> -
> class Stream
> {
> typedef std::set<SpiceVideoCodecType> codecs_t;
> @@ -87,13 +69,17 @@ public:
> const codecs_t &client_codecs() { return codecs; }
> bool streaming_requested() { return is_streaming; }
>
> + template <typename Message, typename ...PayloadArgs>
> + void send(PayloadArgs... payload)
I'd use perfect forwarding here.
> + {
> + Message message(payload...);
> + std::lock_guard<std::mutex> stream_guard(mutex);
> + message.write_header(*this);
> + message.write_message_body(*this, payload...);
> + }
> +
> int read_command(bool blocking);
> - size_t write_all(const void *buf, const size_t len);
> - int send_format(unsigned w, unsigned h, uint8_t c);
> - int send_frame(const void *buf, const unsigned size);
> - void send_cursor(uint16_t width, uint16_t height,
> - uint16_t hotspot_x, uint16_t hotspot_y,
> - std::function<void(uint32_t *)> fill_cursor);
> + void write_all(const char *operation, const void *buf, const size_t len);
>
> private:
> int have_something_to_read(int timeout);
> @@ -109,6 +95,117 @@ private:
> bool is_streaming = false;
> };
>
> +template <typename Payload, typename Info, unsigned Type>
> +class Message
> +{
> +public:
> + template <typename ...PayloadArgs>
> + Message(PayloadArgs... payload)
Also perfect forwarding. And I'd still rather see "PayloadArgs...
payload_args" here :) (and to be consistent, in Stream::send(...)
above, too)
> + : hdr(StreamDevHeader {
> + .protocol_version = STREAM_DEVICE_PROTOCOL,
> + .padding = 0, // Workaround GCC bug "sorry: not implemented"
> + .type = Type,
> + .size = (uint32_t) Info::size(payload...)
> + })
> + { }
> + void write_header(Stream &stream)
> + {
> + stream.write_all("header", &hdr, sizeof(hdr));
> + }
> +
> +protected:
> + StreamDevHeader hdr;
> + typedef Payload payload_t;
> +};
> +
> +class FormatMessage : public Message<StreamMsgFormat, FormatMessage, STREAM_TYPE_FORMAT>
> +{
> +public:
> + FormatMessage(unsigned w, unsigned h, uint8_t c) : Message(w, h, c) {}
> + static size_t size(unsigned width, unsigned height, uint8_t codec)
> + {
> + return sizeof(payload_t);
> + }
> + void write_message_body(Stream &stream, unsigned w, unsigned h, uint8_t c)
> + {
> + StreamMsgFormat msg = { .width = w, .height = h, .codec = c, .padding1 = {} };
> + stream.write_all("format", &msg, sizeof(msg));
> + }
> +};
> +
> +class FrameMessage : public Message<StreamMsgData, FrameMessage, STREAM_TYPE_DATA>
> +{
> +public:
> + FrameMessage(const void *frame, size_t length) : Message(frame, length) {}
> + static size_t size(const void *frame, size_t length)
> + {
> + return sizeof(payload_t) + length;
> + }
> + void write_message_body(Stream &stream, const void *frame, size_t length)
> + {
> + stream.write_all("frame", frame, length);
> + }
> +};
> +
> +class CapabilitiesMessage : public Message<StreamMsgData, CapabilitiesMessage, STREAM_TYPE_CAPABILITIES>
> +{
> +public:
> + CapabilitiesMessage() : Message() {}
> + static size_t size()
> + {
> + return sizeof(payload_t);
> + }
> + void write_message_body(Stream &stream)
> + {
> + /* No body for capabilities message */
> + }
> +};
> +
> +class X11CursorMessage : public Message<StreamMsgCursorSet, X11CursorMessage, STREAM_TYPE_CURSOR_SET>
> +{
> +public:
> + X11CursorMessage(XFixesCursorImage *cursor): Message(cursor) {}
> + static size_t size(XFixesCursorImage *cursor)
> + {
> + return sizeof(payload_t) + sizeof(uint32_t) * pixel_count(cursor);
> + }
> +
> + void write_message_body(Stream &stream, XFixesCursorImage *cursor)
> + {
> + StreamMsgCursorSet msg = {
> + .width = cursor->width,
> + .height = cursor->height,
> + .hot_spot_x = cursor->xhot,
> + .hot_spot_y = cursor->yhot,
> + .type = SPICE_CURSOR_TYPE_ALPHA,
> + .padding1 = { },
> + .data = { }
> + };
> +
> + size_t pixcount = pixel_count(cursor);
> + size_t pixsize = pixcount * sizeof(uint32_t);
> + std::unique_ptr<uint32_t[]> pixels(new uint32_t[pixcount]);
> + uint32_t *pixbuf = pixels.get();
> + fill_pixels(cursor, pixcount, pixbuf);
> +
> + stream.write_all("cursor message", &msg, sizeof(msg));
> + stream.write_all("cursor pixels", pixbuf, pixsize);
> + }
> +
> +private:
> + static size_t pixel_count(XFixesCursorImage *cursor)
> + {
> + return cursor->width * cursor->height;
> + }
> +
> + void fill_pixels(XFixesCursorImage *cursor, unsigned count, uint32_t *pixbuf)
> + {
> + for (unsigned i = 0; i < count; ++i) {
> + pixbuf[i] = cursor->pixels[i];
> + }
> + }
Both methods above const. fill_pixels() used only once and very short,
perhaps drop the method and use the code directly?
> +};
I like how the message classes came out nice and terse :)
> +
> }} // namespace spice::streaming_agent
>
> static bool quit_requested = false;
> @@ -166,15 +263,7 @@ void Stream::handle_stream_capabilities(uint32_t len)
> }
>
> // we currently do not support extensions so just reply so
> - StreamDevHeader hdr = {
> - STREAM_DEVICE_PROTOCOL,
> - 0,
> - STREAM_TYPE_CAPABILITIES,
> - 0
> - };
> - if (write_all(&hdr, sizeof(hdr)) != sizeof(hdr)) {
> - throw std::runtime_error("error writing capabilities");
> - }
> + send<CapabilitiesMessage>();
> }
>
> void Stream::handle_stream_error(uint32_t len)
> @@ -228,7 +317,7 @@ int Stream::read_command(bool blocking)
> return 1;
> }
>
> -size_t Stream::write_all(const void *buf, const size_t len)
> +void Stream::write_all(const char *operation, const void *buf, const size_t len)
> {
> size_t written = 0;
> while (written < len) {
> @@ -237,73 +326,11 @@ size_t Stream::write_all(const void *buf, const size_t len)
> if (errno == EINTR) {
> continue;
> }
> - syslog(LOG_ERR, "write failed - %m");
> - return l;
> + throw WriteError("write failed", operation, errno).syslog();
> }
> written += l;
> }
> - syslog(LOG_DEBUG, "write_all -- %u bytes written\n", (unsigned)written);
> - return written;
> -}
> -
> -int Stream::send_format(unsigned w, unsigned h, uint8_t c)
> -{
> - const size_t msgsize = sizeof(FormatMessage);
> - const size_t hdrsize = sizeof(StreamDevHeader);
> - FormatMessage msg = {
> - .hdr = {
> - .protocol_version = STREAM_DEVICE_PROTOCOL,
> - .padding = 0, // Workaround GCC "not implemented" bug
> - .type = STREAM_TYPE_FORMAT,
> - .size = msgsize - hdrsize
> - },
> - .msg = {
> - .width = w,
> - .height = h,
> - .codec = c,
> - .padding1 = { }
> - }
> - };
> - syslog(LOG_DEBUG, "writing format\n");
> - std::lock_guard<std::mutex> stream_guard(mutex);
> - if (write_all(&msg, msgsize) != msgsize) {
> - return EXIT_FAILURE;
> - }
> - return EXIT_SUCCESS;
> -}
> -
> -int Stream::send_frame(const void *buf, const unsigned size)
> -{
> - ssize_t n;
> - const size_t msgsize = sizeof(FormatMessage);
> - DataMessage msg = {
> - .hdr = {
> - .protocol_version = STREAM_DEVICE_PROTOCOL,
> - .padding = 0, // Workaround GCC "not implemented" bug
> - .type = STREAM_TYPE_DATA,
> - .size = size /* includes only the body? */
> - },
> - .msg = {}
> - };
> -
> - std::lock_guard<std::mutex> stream_guard(mutex);
> - n = write_all(&msg, msgsize);
> - syslog(LOG_DEBUG,
> - "wrote %ld bytes of header of data msg with frame of size %u bytes\n",
> - n, msg.hdr.size);
> - if (n != msgsize) {
> - syslog(LOG_WARNING, "write_all header: wrote %ld expected %lu\n",
> - n, msgsize);
> - return EXIT_FAILURE;
> - }
> - n = write_all(buf, size);
> - syslog(LOG_DEBUG, "wrote data msg body of size %ld\n", n);
> - if (n != size) {
> - syslog(LOG_WARNING, "write_all header: wrote %ld expected %u\n",
> - n, size);
> - return EXIT_FAILURE;
> - }
> - return EXIT_SUCCESS;
> + syslog(LOG_DEBUG, "write_all -- %zu bytes written\n", written);
> }
>
> /* returns current time in micro-seconds */
> @@ -350,46 +377,6 @@ static void usage(const char *progname)
> exit(1);
> }
>
> -void
> -Stream::send_cursor(uint16_t width, uint16_t height,
> - uint16_t hotspot_x, uint16_t hotspot_y,
> - std::function<void(uint32_t *)> fill_cursor)
> -{
> - if (width >= STREAM_MSG_CURSOR_SET_MAX_WIDTH || height >= STREAM_MSG_CURSOR_SET_MAX_HEIGHT) {
> - return;
> - }
> -
> - const uint32_t msgsize = sizeof(CursorMessage) + width * height * sizeof(uint32_t);
> - const uint32_t hdrsize = sizeof(StreamDevHeader);
> -
> - std::unique_ptr<uint8_t[]> storage(new uint8_t[msgsize]);
> -
> - CursorMessage *cursor_msg =
> - new(storage.get()) CursorMessage {
> - .hdr = {
> - .protocol_version = STREAM_DEVICE_PROTOCOL,
> - .padding = 0, // Workaround GCC internal / not implemented compiler error
> - .type = STREAM_TYPE_CURSOR_SET,
> - .size = msgsize - hdrsize
> - },
> - .msg = {
> - .width = width,
> - .height = height,
> - .hot_spot_x = hotspot_x,
> - .hot_spot_y = hotspot_y,
> - .type = SPICE_CURSOR_TYPE_ALPHA,
> - .padding1 = { },
> - .data = { }
> - }
> - };
> -
> - uint32_t *pixels = reinterpret_cast<uint32_t *>(cursor_msg->msg.data);
> - fill_cursor(pixels);
> -
> - std::lock_guard<std::mutex> stream_guard(mutex);
> - write_all(storage.get(), msgsize);
> -}
> -
> static void cursor_changes(Stream *stream, Display *display, int event_base)
> {
> unsigned long last_serial = 0;
> @@ -411,12 +398,7 @@ static void cursor_changes(Stream *stream, Display *display, int event_base)
> }
>
> last_serial = cursor->cursor_serial;
> - auto fill_cursor = [cursor](uint32_t *pixels) {
> - for (unsigned i = 0; i < cursor->width * cursor->height; ++i)
> - pixels[i] = cursor->pixels[i];
> - };
> - stream->send_cursor(cursor->width, cursor->height,
> - cursor->xhot, cursor->yhot, fill_cursor);
> + stream->send<X11CursorMessage>(cursor);
> }
> }
>
> @@ -471,9 +453,7 @@ do_capture(Stream &stream, const char *streamport, FILE *f_log)
>
> syslog(LOG_DEBUG, "wXh %uX%u codec=%u\n", width, height, codec);
>
> - if (stream.send_format(width, height, codec) == EXIT_FAILURE) {
> - throw std::runtime_error("FAILED to send format message");
> - }
> + stream.send<FormatMessage>(width, height, codec);
> }
> if (f_log) {
> if (log_binary) {
> @@ -484,10 +464,7 @@ do_capture(Stream &stream, const char *streamport, FILE *f_log)
> hexdump(frame.buffer, frame.buffer_size, f_log);
> }
> }
> - if (stream.send_frame(frame.buffer, frame.buffer_size) == EXIT_FAILURE) {
> - syslog(LOG_ERR, "FAILED to send a frame\n");
> - break;
> - }
> + stream.send<FrameMessage>(frame.buffer, frame.buffer_size);
> //usleep(1);
> if (stream.read_command(false) < 0) {
> syslog(LOG_ERR, "FAILED to read command\n");
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