ui/vnc: Introduce the VncWorker type

The worker thread copies data in VncState to avoid race, but some
data are too big to copy. Such data are held with pointers to avoid
the overhead to copy, but it requires tedious memory management and
makes them vulnerable to race.

Introduce the VncWorker type to contain all data shared without copying.
It allows allocating and freeing all shared data at once and shows that
the race with the worker thread needs to be taken care of when
accessing them.

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20250603-zlib-v3-2-20b857bd8d05@rsg.ci.i.u-tokyo.ac.jp>

1 files changed, 31 insertions, 18 deletions

diff --git a/ui/vnc.h b/ui/vnc.h
index 8df0cbab25..f2dab2f4d9 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -272,8 +272,6 @@ struct VncState
     gboolean disconnecting;
 
     DECLARE_BITMAP(dirty[VNC_MAX_HEIGHT], VNC_DIRTY_BITS);
-    uint8_t **lossy_rect; /* Not an Array to avoid costly memcpy in
-                           * vnc-jobs-async.c */
 
     VncDisplay *vd;
     VncStateUpdate update; /* Most recent pending request from client */
@@ -341,10 +339,7 @@ struct VncState
     /* Encoding specific, if you add something here, don't forget to
      *  update vnc_async_encoding_start()
      */
-    VncTight *tight;
-    VncZlib *zlib;
     VncHextile hextile;
-    VncZrle *zrle;
     VncZywrle zywrle;
 
     Notifier mouse_mode_notifier;
@@ -356,6 +351,19 @@ struct VncState
     QTAILQ_ENTRY(VncState) next;
 };
 
+typedef struct VncWorker {
+    uint8_t lossy_rect[VNC_STAT_ROWS][VNC_STAT_COLS];
+
+    VncTight tight;
+    VncZlib zlib;
+    VncZrle zrle;
+} VncWorker;
+
+typedef struct VncConnection {
+    VncState vs;
+    VncWorker worker;
+} VncConnection;
+
 
 /*****************************************************************************
  *
@@ -602,10 +610,11 @@ int vnc_server_fb_stride(VncDisplay *vd);
 
 void vnc_convert_pixel(VncState *vs, uint8_t *buf, uint32_t v);
 double vnc_update_freq(VncState *vs, int x, int y, int w, int h);
-void vnc_sent_lossy_rect(VncState *vs, int x, int y, int w, int h);
+void vnc_sent_lossy_rect(VncWorker *worker, int x, int y, int w, int h);
 
 /* Encodings */
-int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
+int vnc_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                int x, int y, int w, int h);
 
 int vnc_raw_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
 
@@ -615,17 +624,21 @@ void vnc_hextile_set_pixel_conversion(VncState *vs, int generic);
 
 void *vnc_zlib_zalloc(void *x, unsigned items, unsigned size);
 void vnc_zlib_zfree(void *x, void *addr);
-int vnc_zlib_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
-void vnc_zlib_clear(VncState *vs);
-
-int vnc_tight_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
-int vnc_tight_png_send_framebuffer_update(VncState *vs, int x, int y,
-                                          int w, int h);
-void vnc_tight_clear(VncState *vs);
-
-int vnc_zrle_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
-int vnc_zywrle_send_framebuffer_update(VncState *vs, int x, int y, int w, int h);
-void vnc_zrle_clear(VncState *vs);
+int vnc_zlib_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                     int x, int y, int w, int h);
+void vnc_zlib_clear(VncWorker *worker);
+
+int vnc_tight_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                      int x, int y, int w, int h);
+int vnc_tight_png_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                          int x, int y, int w, int h);
+void vnc_tight_clear(VncWorker *worker);
+
+int vnc_zrle_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                     int x, int y, int w, int h);
+int vnc_zywrle_send_framebuffer_update(VncState *vs, VncWorker *worker,
+                                       int x, int y, int w, int h);
+void vnc_zrle_clear(VncWorker *worker);
 
 /* vnc-clipboard.c */
 void vnc_server_cut_text_caps(VncState *vs);