diff options
| -rw-r--r-- | ui/vnc.c | 72 | ||||
| -rw-r--r-- | ui/vnc.h | 6 |
2 files changed, 70 insertions, 8 deletions
@@ -60,6 +60,7 @@ static QTAILQ_HEAD(, VncDisplay) vnc_displays = static int vnc_cursor_define(VncState *vs); static void vnc_release_modifiers(VncState *vs); +static void vnc_update_throttle_offset(VncState *vs); static void vnc_set_share_mode(VncState *vs, VncShareMode mode) { @@ -766,6 +767,7 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl, vnc_set_area_dirty(vs->dirty, vd, 0, 0, vnc_width(vd), vnc_height(vd)); + vnc_update_throttle_offset(vs); } } @@ -961,16 +963,67 @@ static int find_and_clear_dirty_height(VncState *vs, return h; } +/* + * Figure out how much pending data we should allow in the output + * buffer before we throttle incremental display updates, and/or + * drop audio samples. + * + * We allow for equiv of 1 full display's worth of FB updates, + * and 1 second of audio samples. If audio backlog was larger + * than that the client would already suffering awful audio + * glitches, so dropping samples is no worse really). + */ +static void vnc_update_throttle_offset(VncState *vs) +{ + size_t offset = + vs->client_width * vs->client_height * vs->client_pf.bytes_per_pixel; + + if (vs->audio_cap) { + int freq = vs->as.freq; + /* We don't limit freq when reading settings from client, so + * it could be upto MAX_INT in size. 48khz is a sensible + * upper bound for trustworthy clients */ + int bps; + if (freq > 48000) { + freq = 48000; + } + switch (vs->as.fmt) { + default: + case AUD_FMT_U8: + case AUD_FMT_S8: + bps = 1; + break; + case AUD_FMT_U16: + case AUD_FMT_S16: + bps = 2; + break; + case AUD_FMT_U32: + case AUD_FMT_S32: + bps = 4; + break; + } + offset += freq * bps * vs->as.nchannels; + } + + /* Put a floor of 1MB on offset, so that if we have a large pending + * buffer and the display is resized to a small size & back again + * we don't suddenly apply a tiny send limit + */ + offset = MAX(offset, 1024 * 1024); + + vs->throttle_output_offset = offset; +} + static bool vnc_should_update(VncState *vs) { switch (vs->update) { case VNC_STATE_UPDATE_NONE: break; case VNC_STATE_UPDATE_INCREMENTAL: - /* Only allow incremental updates if the output buffer - * is empty, or if audio capture is enabled. + /* Only allow incremental updates if the pending send queue + * is less than the permitted threshold */ - if (!vs->output.offset || vs->audio_cap) { + if (vs->output.offset < vs->throttle_output_offset) { return true; } break; @@ -1084,11 +1137,13 @@ static void audio_capture(void *opaque, void *buf, int size) VncState *vs = opaque; vnc_lock_output(vs); - vnc_write_u8(vs, VNC_MSG_SERVER_QEMU); - vnc_write_u8(vs, VNC_MSG_SERVER_QEMU_AUDIO); - vnc_write_u16(vs, VNC_MSG_SERVER_QEMU_AUDIO_DATA); - vnc_write_u32(vs, size); - vnc_write(vs, buf, size); + if (vs->output.offset < vs->throttle_output_offset) { + vnc_write_u8(vs, VNC_MSG_SERVER_QEMU); + vnc_write_u8(vs, VNC_MSG_SERVER_QEMU_AUDIO); + vnc_write_u16(vs, VNC_MSG_SERVER_QEMU_AUDIO_DATA); + vnc_write_u32(vs, size); + vnc_write(vs, buf, size); + } vnc_unlock_output(vs); vnc_flush(vs); } @@ -2288,6 +2343,7 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len) break; } + vnc_update_throttle_offset(vs); vnc_read_when(vs, protocol_client_msg, 1); return 0; } @@ -298,6 +298,12 @@ struct VncState VncClientInfo *info; + /* We allow multiple incremental updates or audio capture + * samples to be queued in output buffer, provided the + * buffer size doesn't exceed this threshold. The value + * is calculating dynamically based on framebuffer size + * and audio sample settings in vnc_update_throttle_offset() */ + size_t throttle_output_offset; Buffer output; Buffer input; /* current output mode information */ |