[Spice-devel] [PATCH 11/17] Move read, write and locking into the 'Stream' class

Christophe de Dinechin christophe.de.dinechin at gmail.com
Tue Feb 20 09:47:16 UTC 2018



> On 20 Feb 2018, at 10:43, Lukáš Hrázký <lhrazky at redhat.com> wrote:
> 
> On Fri, 2018-02-16 at 17:15 +0100, Christophe de Dinechin wrote:
>> From: Christophe de Dinechin <dinechin at redhat.com>
>> 
>> Signed-off-by: Christophe de Dinechin <dinechin at redhat.com>
>> ---
>> src/spice-streaming-agent.cpp | 86 +++++++++++++++++++++++--------------------
>> 1 file changed, 47 insertions(+), 39 deletions(-)
>> 
>> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
>> index f0d79ae..a989ee7 100644
>> --- a/src/spice-streaming-agent.cpp
>> +++ b/src/spice-streaming-agent.cpp
>> @@ -71,18 +71,30 @@ class Stream
>> public:
>>     Stream(const char *name)
> 
> I would like to name the class something more descriptive for what it
> is becoming. Class named Stream in a file named "stream.{cpp,hpp}"
> could be almost anything.

But it’s not named “Stream”, it’s called “spice::streaming_agent::Stream” ;-)

I chose short names because I was in that namespace. Otherwise, I agree with you.

Do you think that the name is still too vague even within the namespace?

> My best name is StreamDispatcher so far, not
> entirely happy about it :)


> 
>>     {
>> -        fd = open(name, O_RDWR);
>> -        if (fd < 0)
>> +        streamfd = open(name, O_RDWR);
>> +        if (streamfd < 0)
>>             throw std::runtime_error("failed to open streaming device");
>>     }
>>     ~Stream()
>>     {
>> -        close(fd);
>> +        close(streamfd);
>>     }
>> -    operator int() { return fd; }
>> +    operator int() { return streamfd; }
>> +
>> +    int have_something_to_read(int timeout);
>> +    int read_command_from_device(void);
>> +    int read_command(bool blocking);
>> +
>> +    size_t write_all(const void *buf, const size_t len);
> 
> This method could also use a better name. write_bytes()?
> write_buffer()?

I intended to do a rename in a follow up. My current choice was “write_packet”, because precisely, it’s not writing bytes or a buffer, it’s making sure the whole packet gets sent.

> 
>> +    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);
>> 
>> private:
>> -    int fd = -1;
>> +    int streamfd = -1;
>> +    std::mutex mutex;
>> };
>> 
>> }} // namespace spice::streaming_agent
>> @@ -92,9 +104,8 @@ static bool streaming_requested = false;
>> static bool quit_requested = false;
>> static bool log_binary = false;
>> static std::set<SpiceVideoCodecType> client_codecs;
>> -static std::mutex stream_mtx;
>> 
>> -static int have_something_to_read(int streamfd, int timeout)
>> +int Stream::have_something_to_read(int timeout)
>> {
>>     struct pollfd pollfd = {streamfd, POLLIN, 0};
>> 
>> @@ -110,13 +121,13 @@ static int have_something_to_read(int streamfd, int timeout)
>>     return 0;
>> }
>> 
>> -static int read_command_from_device(int streamfd)
>> +int Stream::read_command_from_device()
>> {
>>     StreamDevHeader hdr;
>>     uint8_t msg[64];
>>     int n;
>> 
>> -    std::lock_guard<std::mutex> stream_guard(stream_mtx);
>> +    std::lock_guard<std::mutex> stream_guard(mutex);
>>     n = read(streamfd, &hdr, sizeof(hdr));
>>     if (n != sizeof(hdr)) {
>>         syslog(LOG_WARNING,
>> @@ -155,29 +166,28 @@ static int read_command_from_device(int streamfd)
>>     return 1;
>> }
>> 
>> -static int read_command(int streamfd, bool blocking)
>> +int Stream::read_command(bool blocking)
>> {
>>     int timeout = blocking?-1:0;
>>     while (!quit_requested) {
>> -        if (!have_something_to_read(streamfd, timeout)) {
>> +        if (!have_something_to_read(timeout)) {
>>             if (!blocking) {
>>                 return 0;
>>             }
>>             sleep(1);
>>             continue;
>>         }
>> -        return read_command_from_device(streamfd);
>> +        return read_command_from_device();
>>     }
>> 
>>     return 1;
>> }
>> 
>> -static size_t
>> -write_all(int fd, const void *buf, const size_t len)
>> +size_t Stream::write_all(const void *buf, const size_t len)
>> {
>>     size_t written = 0;
>>     while (written < len) {
>> -        int l = write(fd, (const char *) buf + written, len - written);
>> +        int l = write(streamfd, (const char *) buf + written, len - written);
>>         if (l < 0) {
>>             if (errno == EINTR) {
>>                 continue;
>> @@ -191,7 +201,7 @@ write_all(int fd, const void *buf, const size_t len)
>>     return written;
>> }
>> 
>> -static int spice_stream_send_format(int streamfd, unsigned w, unsigned h, uint8_t c)
>> +int Stream::send_format(unsigned w, unsigned h, uint8_t c)
>> {
>>     const size_t msgsize = sizeof(FormatMessage);
>>     const size_t hdrsize  = sizeof(StreamDevHeader);
>> @@ -210,14 +220,14 @@ static int spice_stream_send_format(int streamfd, unsigned w, unsigned h, uint8_
>>         }
>>     };
>>     syslog(LOG_DEBUG, "writing format\n");
>> -    std::lock_guard<std::mutex> stream_guard(stream_mtx);
>> -    if (write_all(streamfd, &msg, msgsize) != msgsize) {
>> +    std::lock_guard<std::mutex> stream_guard(mutex);
>> +    if (write_all(&msg, msgsize) != msgsize) {
>>         return EXIT_FAILURE;
>>     }
>>     return EXIT_SUCCESS;
>> }
>> 
>> -static int spice_stream_send_frame(int streamfd, const void *buf, const unsigned size)
>> +int Stream::send_frame(const void *buf, const unsigned size)
>> {
>>     ssize_t n;
>>     const size_t msgsize = sizeof(FormatMessage);
>> @@ -231,8 +241,8 @@ static int spice_stream_send_frame(int streamfd, const void *buf, const unsigned
>>         .msg = {}
>>     };
>> 
>> -    std::lock_guard<std::mutex> stream_guard(stream_mtx);
>> -    n = write_all(streamfd, &msg, msgsize);
>> +    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);
>> @@ -241,7 +251,7 @@ static int spice_stream_send_frame(int streamfd, const void *buf, const unsigned
>>                n, msgsize);
>>         return EXIT_FAILURE;
>>     }
>> -    n = write_all(streamfd, buf, size);
>> +    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",
>> @@ -294,11 +304,10 @@ static void usage(const char *progname)
>>     exit(1);
>> }
>> 
>> -static void
>> -send_cursor(int streamfd,
>> -            uint16_t width, uint16_t height,
>> -            uint16_t hotspot_x, uint16_t hotspot_y,
>> -            std::function<void(uint32_t *)> fill_cursor)
>> +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)
>> @@ -332,11 +341,11 @@ send_cursor(int streamfd,
>>     uint32_t *pixels = reinterpret_cast<uint32_t *>(cursor_msg->msg.data);
>>     fill_cursor(pixels);
>> 
>> -    std::lock_guard<std::mutex> stream_guard(stream_mtx);
>> -    write_all(streamfd, storage.get(), cursor_msgsize);
>> +    std::lock_guard<std::mutex> stream_guard(mutex);
>> +    write_all(storage.get(), cursor_msgsize);
>> }
>> 
>> -static void cursor_changes(int streamfd, Display *display, int event_base)
>> +static void cursor_changes(Stream *stream, Display *display, int event_base)
>> {
>>     unsigned long last_serial = 0;
>> 
>> @@ -358,18 +367,18 @@ static void cursor_changes(int streamfd, Display *display, int event_base)
>>             for (unsigned i = 0; i < cursor->width * cursor->height; ++i)
>>                 pixels[i] = cursor->pixels[i];
>>         };
>> -        send_cursor(streamfd,
>> -                    cursor->width, cursor->height, cursor->xhot, cursor->yhot, fill_cursor);
>> +        stream->send_cursor(cursor->width, cursor->height,
>> +                            cursor->xhot, cursor->yhot, fill_cursor);
>>     }
>> }
>> 
>> static void
>> -do_capture(int streamfd, const char *streamport, FILE *f_log)
>> +do_capture(Stream &stream, const char *streamport, FILE *f_log)
>> {
>>     unsigned int frame_count = 0;
>>     while (!quit_requested) {
>>         while (!quit_requested && !streaming_requested) {
>> -            if (read_command(streamfd, true) < 0) {
>> +            if (stream.read_command(true) < 0) {
>>                 syslog(LOG_ERR, "FAILED to read command\n");
>>                 return;
>>             }
>> @@ -413,7 +422,7 @@ do_capture(int streamfd, const char *streamport, FILE *f_log)
>> 
>>                 syslog(LOG_DEBUG, "wXh %uX%u  codec=%u\n", width, height, codec);
>> 
>> -                if (spice_stream_send_format(streamfd, width, height, codec) == EXIT_FAILURE)
>> +                if (stream.send_format(width, height, codec) == EXIT_FAILURE)
>>                     throw std::runtime_error("FAILED to send format message");
>>             }
>>             if (f_log) {
>> @@ -425,13 +434,12 @@ do_capture(int streamfd, const char *streamport, FILE *f_log)
>>                     hexdump(frame.buffer, frame.buffer_size, f_log);
>>                 }
>>             }
>> -            if (spice_stream_send_frame(streamfd,
>> -                                        frame.buffer, frame.buffer_size) == EXIT_FAILURE) {
>> +            if (stream.send_frame(frame.buffer, frame.buffer_size) == EXIT_FAILURE) {
>>                 syslog(LOG_ERR, "FAILED to send a frame\n");
>>                 break;
>>             }
>>             //usleep(1);
>> -            if (read_command(streamfd, false) < 0) {
>> +            if (stream.read_command(false) < 0) {
>>                 syslog(LOG_ERR, "FAILED to read command\n");
>>                 return;
>>             }
>> @@ -520,7 +528,7 @@ int main(int argc, char* argv[])
>>     XFixesSelectCursorInput(display, rootwindow, XFixesDisplayCursorNotifyMask);
>> 
>>     Stream streamfd(streamport);
>> -    std::thread cursor_th(cursor_changes, (int) streamfd, display, event_base);
>> +    std::thread cursor_th(cursor_changes, &streamfd, display, event_base);
>>     cursor_th.detach();
>> 
>>     int ret = EXIT_SUCCESS;



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