Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-20151116-1' into staging

vnc: buffer code improvements, bugfixes.

# gpg: Signature made Mon 16 Nov 2015 17:20:02 GMT using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-vnc-20151116-1:
  vnc: fix mismerge
  buffer: allow a buffer to shrink gracefully
  buffer: factor out buffer_adj_size
  buffer: factor out buffer_req_size
  vnc: recycle empty vs->output buffer
  vnc: fix local state init
  vnc: only alloc server surface with clients connected
  vnc: use vnc_{width,height} in vnc_set_area_dirty
  vnc: factor out vnc_update_server_surface
  vnc: add vnc_width+vnc_height helpers
  vnc: zap dead code
  vnc-jobs: move buffer reset, use new buffer move
  vnc: kill jobs queue buffer
  vnc: attach names to buffers
  buffer: add tracing
  buffer: add buffer_shrink
  buffer: add buffer_move
  buffer: add buffer_move_empty
  buffer: add buffer_init
  buffer: make the Buffer capacity increase in powers of two

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

5 files changed, 245 insertions, 40 deletions

diff --git a/include/qemu/buffer.h b/include/qemu/buffer.h
index b380cec6fa..dead9b77e1 100644
--- a/include/qemu/buffer.h
+++ b/include/qemu/buffer.h
@@ -34,12 +34,35 @@ typedef struct Buffer Buffer;
  */
 
 struct Buffer {
+    char *name;
     size_t capacity;
     size_t offset;
+    uint64_t avg_size;
     uint8_t *buffer;
 };
 
 /**
+ * buffer_init:
+ * @buffer: the buffer object
+ * @name: buffer name
+ *
+ * Optionally attach a name to the buffer, to make it easier
+ * to identify in debug traces.
+ */
+void buffer_init(Buffer *buffer, const char *name, ...)
+        GCC_FMT_ATTR(2, 3);
+
+/**
+ * buffer_shrink:
+ * @buffer: the buffer object
+ *
+ * Try to shrink the buffer.  Checks current buffer capacity and size
+ * and reduces capacity in case only a fraction of the buffer is
+ * actually used.
+ */
+void buffer_shrink(Buffer *buffer);
+
+/**
  * buffer_reserve:
  * @buffer: the buffer object
  * @len: the minimum required free space
@@ -115,4 +138,24 @@ uint8_t *buffer_end(Buffer *buffer);
  */
 gboolean buffer_empty(Buffer *buffer);
 
+/**
+ * buffer_move_empty:
+ * @to: destination buffer object
+ * @from: source buffer object
+ *
+ * Moves buffer, without copying data.  'to' buffer must be empty.
+ * 'from' buffer is empty and zero-sized on return.
+ */
+void buffer_move_empty(Buffer *to, Buffer *from);
+
+/**
+ * buffer_move:
+ * @to: destination buffer object
+ * @from: source buffer object
+ *
+ * Moves buffer, copying data (unless 'to' buffer happens to be empty).
+ * 'from' buffer is empty and zero-sized on return.
+ */
+void buffer_move(Buffer *to, Buffer *from);
+
 #endif /* QEMU_BUFFER_H__ */
diff --git a/trace-events b/trace-events
index ef6bc41a56..0b0ff02442 100644
--- a/trace-events
+++ b/trace-events
@@ -1419,6 +1419,12 @@ ppc_tb_adjust(uint64_t offs1, uint64_t offs2, int64_t diff, int64_t seconds) "ad
 prep_io_800_writeb(uint32_t addr, uint32_t val) "0x%08" PRIx32 " => 0x%02" PRIx32
 prep_io_800_readb(uint32_t addr, uint32_t retval) "0x%08" PRIx32 " <= 0x%02" PRIx32
 
+# io/buffer.c
+buffer_resize(const char *buf, size_t olen, size_t len) "%s: old %zd, new %zd"
+buffer_move_empty(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
+buffer_move(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
+buffer_free(const char *buf, size_t len) "%s: capacity %zd"
+
 # util/hbitmap.c
 hbitmap_iter_skip_words(const void *hb, void *hbi, uint64_t pos, unsigned long cur) "hb %p hbi %p pos %"PRId64" cur 0x%lx"
 hbitmap_reset(void *hb, uint64_t start, uint64_t count, uint64_t sbit, uint64_t ebit) "hb %p items %"PRIu64",%"PRIu64" bits %"PRIu64"..%"PRIu64
diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
index 9512b87183..aa21191ea2 100644
--- a/ui/vnc-jobs.c
+++ b/ui/vnc-jobs.c
@@ -29,6 +29,7 @@
 #include "vnc.h"
 #include "vnc-jobs.h"
 #include "qemu/sockets.h"
+#include "qemu/main-loop.h"
 #include "block/aio.h"
 
 /*
@@ -54,7 +55,6 @@ struct VncJobQueue {
     QemuCond cond;
     QemuMutex mutex;
     QemuThread thread;
-    Buffer buffer;
     bool exit;
     QTAILQ_HEAD(, VncJob) jobs;
 };
@@ -166,8 +166,11 @@ void vnc_jobs_consume_buffer(VncState *vs)
 
     vnc_lock_output(vs);
     if (vs->jobs_buffer.offset) {
-        vnc_write(vs, vs->jobs_buffer.buffer, vs->jobs_buffer.offset);
-        buffer_reset(&vs->jobs_buffer);
+        if (vs->csock != -1 && buffer_empty(&vs->output)) {
+            qemu_set_fd_handler(vs->csock, vnc_client_read,
+                                vnc_client_write, vs);
+        }
+        buffer_move(&vs->output, &vs->jobs_buffer);
     }
     flush = vs->csock != -1 && vs->abort != true;
     vnc_unlock_output(vs);
@@ -182,6 +185,9 @@ void vnc_jobs_consume_buffer(VncState *vs)
  */
 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 {
+    buffer_init(&local->output, "vnc-worker-output");
+    local->csock = -1; /* Don't do any network work on this thread */
+
     local->vnc_encoding = orig->vnc_encoding;
     local->features = orig->features;
     local->vd = orig->vd;
@@ -193,10 +199,6 @@ static void vnc_async_encoding_start(VncState *orig, VncState *local)
     local->zlib = orig->zlib;
     local->hextile = orig->hextile;
     local->zrle = orig->zrle;
-    local->output =  queue->buffer;
-    local->csock = -1; /* Don't do any network work on this thread */
-
-    buffer_reset(&local->output);
 }
 
 static void vnc_async_encoding_end(VncState *orig, VncState *local)
@@ -206,15 +208,13 @@ static void vnc_async_encoding_end(VncState *orig, VncState *local)
     orig->hextile = local->hextile;
     orig->zrle = local->zrle;
     orig->lossy_rect = local->lossy_rect;
-
-    queue->buffer = local->output;
 }
 
 static int vnc_worker_thread_loop(VncJobQueue *queue)
 {
     VncJob *job;
     VncRectEntry *entry, *tmp;
-    VncState vs;
+    VncState vs = {};
     int n_rectangles;
     int saved_offset;
 
@@ -235,6 +235,14 @@ static int vnc_worker_thread_loop(VncJobQueue *queue)
         vnc_unlock_output(job->vs);
         goto disconnected;
     }
+    if (buffer_empty(&job->vs->output)) {
+        /*
+         * Looks like a NOP as it obviously moves no data.  But it
+         * moves the empty buffer, so we don't have to malloc a new
+         * one for vs.output
+         */
+        buffer_move_empty(&vs.output, &job->vs->output);
+    }
     vnc_unlock_output(job->vs);
 
     /* Make a local copy of vs and switch output buffers */
@@ -274,14 +282,13 @@ static int vnc_worker_thread_loop(VncJobQueue *queue)
 
     vnc_lock_output(job->vs);
     if (job->vs->csock != -1) {
-        buffer_reserve(&job->vs->jobs_buffer, vs.output.offset);
-        buffer_append(&job->vs->jobs_buffer, vs.output.buffer,
-                      vs.output.offset);
+        buffer_move(&job->vs->jobs_buffer, &vs.output);
         /* Copy persistent encoding data */
         vnc_async_encoding_end(job->vs, &vs);
 
 	qemu_bh_schedule(job->vs->bh);
     }  else {
+        buffer_reset(&vs.output);
         /* Copy persistent encoding data */
         vnc_async_encoding_end(job->vs, &vs);
     }
@@ -310,7 +317,6 @@ static void vnc_queue_clear(VncJobQueue *q)
 {
     qemu_cond_destroy(&queue->cond);
     qemu_mutex_destroy(&queue->mutex);
-    buffer_free(&queue->buffer);
     g_free(q);
     queue = NULL; /* Unset global queue */
 }
diff --git a/ui/vnc.c b/ui/vnc.c
index f20c08db4a..c9f2fed9c9 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -615,10 +615,25 @@ static void framebuffer_update_request(VncState *vs, int incremental,
 static void vnc_refresh(DisplayChangeListener *dcl);
 static int vnc_refresh_server_surface(VncDisplay *vd);
 
+static int vnc_width(VncDisplay *vd)
+{
+    return MIN(VNC_MAX_WIDTH, ROUND_UP(surface_width(vd->ds),
+                                       VNC_DIRTY_PIXELS_PER_BIT));
+}
+
+static int vnc_height(VncDisplay *vd)
+{
+    return MIN(VNC_MAX_HEIGHT, surface_height(vd->ds));
+}
+
 static void vnc_set_area_dirty(DECLARE_BITMAP(dirty[VNC_MAX_HEIGHT],
                                VNC_MAX_WIDTH / VNC_DIRTY_PIXELS_PER_BIT),
-                               int width, int height,
-                               int x, int y, int w, int h) {
+                               VncDisplay *vd,
+                               int x, int y, int w, int h)
+{
+    int width = vnc_width(vd);
+    int height = vnc_height(vd);
+
     /* this is needed this to ensure we updated all affected
      * blocks if x % VNC_DIRTY_PIXELS_PER_BIT != 0 */
     w += (x % VNC_DIRTY_PIXELS_PER_BIT);
@@ -640,10 +655,8 @@ static void vnc_dpy_update(DisplayChangeListener *dcl,
 {
     VncDisplay *vd = container_of(dcl, VncDisplay, dcl);
     struct VncSurface *s = &vd->guest;
-    int width = pixman_image_get_width(vd->server);
-    int height = pixman_image_get_height(vd->server);
 
-    vnc_set_area_dirty(s->dirty, width, height, x, y, w, h);
+    vnc_set_area_dirty(s->dirty, vd, x, y, w, h);
 }
 
 void vnc_framebuffer_update(VncState *vs, int x, int y, int w, int h,
@@ -713,6 +726,21 @@ void *vnc_server_fb_ptr(VncDisplay *vd, int x, int y)
     return ptr;
 }
 
+static void vnc_update_server_surface(VncDisplay *vd)
+{
+    qemu_pixman_image_unref(vd->server);
+    vd->server = NULL;
+
+    if (QTAILQ_EMPTY(&vd->clients)) {
+        return;
+    }
+
+    vd->server = pixman_image_create_bits(VNC_SERVER_FB_FORMAT,
+                                          vnc_width(vd),
+                                          vnc_height(vd),
+                                          NULL, 0);
+}
+
 static void vnc_dpy_switch(DisplayChangeListener *dcl,
                            DisplaySurface *surface)
 {
@@ -721,26 +749,19 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl,
     int width, height;
 
     vnc_abort_display_jobs(vd);
+    vd->ds = surface;
 
     /* server surface */
-    qemu_pixman_image_unref(vd->server);
-    vd->ds = surface;
-    width = MIN(VNC_MAX_WIDTH, ROUND_UP(surface_width(vd->ds),
-                                        VNC_DIRTY_PIXELS_PER_BIT));
-    height = MIN(VNC_MAX_HEIGHT, surface_height(vd->ds));
-    vd->server = pixman_image_create_bits(VNC_SERVER_FB_FORMAT,
-                                          width, height, NULL, 0);
+    vnc_update_server_surface(vd);
 
     /* guest surface */
-#if 0 /* FIXME */
-    if (ds_get_bytes_per_pixel(ds) != vd->guest.ds->pf.bytes_per_pixel)
-        console_color_init(ds);
-#endif
     qemu_pixman_image_unref(vd->guest.fb);
     vd->guest.fb = pixman_image_ref(surface->image);
     vd->guest.format = surface->format;
+    width = vnc_width(vd);
+    height = vnc_height(vd);
     memset(vd->guest.dirty, 0x00, sizeof(vd->guest.dirty));
-    vnc_set_area_dirty(vd->guest.dirty, width, height, 0, 0,
+    vnc_set_area_dirty(vd->guest.dirty, vd, 0, 0,
                        width, height);
 
     QTAILQ_FOREACH(vs, &vd->clients, next) {
@@ -750,7 +771,7 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl,
             vnc_cursor_define(vs);
         }
         memset(vs->dirty, 0x00, sizeof(vs->dirty));
-        vnc_set_area_dirty(vs->dirty, width, height, 0, 0,
+        vnc_set_area_dirty(vs->dirty, vd, 0, 0,
                            width, height);
     }
 }
@@ -1224,6 +1245,10 @@ void vnc_disconnect_finish(VncState *vs)
     if (vs->initialized) {
         QTAILQ_REMOVE(&vs->vd->clients, vs, next);
         qemu_remove_mouse_mode_change_notifier(&vs->mouse_mode_notifier);
+        if (QTAILQ_EMPTY(&vs->vd->clients)) {
+            /* last client gone */
+            vnc_update_server_surface(vs->vd);
+        }
     }
 
     if (vs->vd->lock_key_sync)
@@ -2006,9 +2031,6 @@ static void ext_key_event(VncState *vs, int down,
 static void framebuffer_update_request(VncState *vs, int incremental,
                                        int x, int y, int w, int h)
 {
-    int width = pixman_image_get_width(vs->vd->server);
-    int height = pixman_image_get_height(vs->vd->server);
-
     vs->need_update = 1;
 
     if (incremental) {
@@ -2016,7 +2038,7 @@ static void framebuffer_update_request(VncState *vs, int incremental,
     }
 
     vs->force_update = 1;
-    vnc_set_area_dirty(vs->dirty, width, height, x, y, w, h);
+    vnc_set_area_dirty(vs->dirty, vs->vd, x, y, w, h);
 }
 
 static void send_ext_key_event_ack(VncState *vs)
@@ -2988,6 +3010,26 @@ static void vnc_connect(VncDisplay *vd, int csock,
     vs->csock = csock;
     vs->vd = vd;
 
+    buffer_init(&vs->input,          "vnc-input/%d", csock);
+    buffer_init(&vs->output,         "vnc-output/%d", csock);
+    buffer_init(&vs->ws_input,       "vnc-ws_input/%d", csock);
+    buffer_init(&vs->ws_output,      "vnc-ws_output/%d", csock);
+    buffer_init(&vs->jobs_buffer,    "vnc-jobs_buffer/%d", csock);
+
+    buffer_init(&vs->tight.tight,    "vnc-tight/%d", csock);
+    buffer_init(&vs->tight.zlib,     "vnc-tight-zlib/%d", csock);
+    buffer_init(&vs->tight.gradient, "vnc-tight-gradient/%d", csock);
+#ifdef CONFIG_VNC_JPEG
+    buffer_init(&vs->tight.jpeg,     "vnc-tight-jpeg/%d", csock);
+#endif
+#ifdef CONFIG_VNC_PNG
+    buffer_init(&vs->tight.png,      "vnc-tight-png/%d", csock);
+#endif
+    buffer_init(&vs->zlib.zlib,      "vnc-zlib/%d", csock);
+    buffer_init(&vs->zrle.zrle,      "vnc-zrle/%d", csock);
+    buffer_init(&vs->zrle.fb,        "vnc-zrle-fb/%d", csock);
+    buffer_init(&vs->zrle.zlib,      "vnc-zrle-zlib/%d", csock);
+
     if (skipauth) {
 	vs->auth = VNC_AUTH_NONE;
 	vs->subauth = VNC_AUTH_INVALID;
@@ -3045,6 +3087,7 @@ void vnc_init_state(VncState *vs)
 {
     vs->initialized = true;
     VncDisplay *vd = vs->vd;
+    bool first_client = QTAILQ_EMPTY(&vd->clients);
 
     vs->last_x = -1;
     vs->last_y = -1;
@@ -3058,6 +3101,9 @@ void vnc_init_state(VncState *vs)
     vs->bh = qemu_bh_new(vnc_jobs_bh, vs);
 
     QTAILQ_INSERT_TAIL(&vd->clients, vs, next);
+    if (first_client) {
+        vnc_update_server_surface(vd);
+    }
 
     graphic_hw_update(vd->dcl.con);
 
@@ -3571,8 +3617,6 @@ void vnc_display_open(const char *id, Error **errp)
 
             if (to) {
                 saddr->u.inet->has_to = true;
-                saddr->u.inet->to = to;
-                saddr->u.inet->has_to = true;
                 saddr->u.inet->to = to + 5900;
             }
             saddr->u.inet->ipv4 = saddr->u.inet->has_ipv4 = has_ipv4;
diff --git a/util/buffer.c b/util/buffer.c
index cedd055680..8b27c08aac 100644
--- a/util/buffer.c
+++ b/util/buffer.c
@@ -19,12 +19,77 @@
  */
 
 #include "qemu/buffer.h"
+#include "trace.h"
+
+#define BUFFER_MIN_INIT_SIZE     4096
+#define BUFFER_MIN_SHRINK_SIZE  65536
+
+/* define the factor alpha for the expentional smoothing
+ * that is used in the average size calculation. a shift
+ * of 7 results in an alpha of 1/2^7. */
+#define BUFFER_AVG_SIZE_SHIFT       7
+
+static size_t buffer_req_size(Buffer *buffer, size_t len)
+{
+    return MAX(BUFFER_MIN_INIT_SIZE,
+               pow2ceil(buffer->offset + len));
+}
+
+static void buffer_adj_size(Buffer *buffer, size_t len)
+{
+    size_t old = buffer->capacity;
+    buffer->capacity = buffer_req_size(buffer, len);
+    buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+    trace_buffer_resize(buffer->name ?: "unnamed",
+                        old, buffer->capacity);
+
+    /* make it even harder for the buffer to shrink, reset average size
+     * to currenty capacity if it is larger than the average. */
+    buffer->avg_size = MAX(buffer->avg_size,
+                           buffer->capacity << BUFFER_AVG_SIZE_SHIFT);
+}
+
+void buffer_init(Buffer *buffer, const char *name, ...)
+{
+    va_list ap;
+
+    va_start(ap, name);
+    buffer->name = g_strdup_vprintf(name, ap);
+    va_end(ap);
+}
+
+static uint64_t buffer_get_avg_size(Buffer *buffer)
+{
+    return buffer->avg_size >> BUFFER_AVG_SIZE_SHIFT;
+}
+
+void buffer_shrink(Buffer *buffer)
+{
+    size_t new;
+
+    /* Calculate the average size of the buffer as
+     * avg_size = avg_size * ( 1 - a ) + required_size * a
+     * where a is 1 / 2 ^ BUFFER_AVG_SIZE_SHIFT. */
+    buffer->avg_size *= (1 << BUFFER_AVG_SIZE_SHIFT) - 1;
+    buffer->avg_size >>= BUFFER_AVG_SIZE_SHIFT;
+    buffer->avg_size += buffer_req_size(buffer, 0);
+
+    /* And then only shrink if the average size of the buffer is much
+     * too big, to avoid bumping up & down the buffers all the time.
+     * realloc() isn't exactly cheap ...  */
+    new = buffer_req_size(buffer, buffer_get_avg_size(buffer));
+    if (new < buffer->capacity >> 3 &&
+        new >= BUFFER_MIN_SHRINK_SIZE) {
+        buffer_adj_size(buffer, buffer_get_avg_size(buffer));
+    }
+
+    buffer_adj_size(buffer, 0);
+}
 
 void buffer_reserve(Buffer *buffer, size_t len)
 {
     if ((buffer->capacity - buffer->offset) < len) {
-        buffer->capacity += (len + 1024);
-        buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+        buffer_adj_size(buffer, len);
     }
 }
 
@@ -41,14 +106,18 @@ uint8_t *buffer_end(Buffer *buffer)
 void buffer_reset(Buffer *buffer)
 {
     buffer->offset = 0;
+    buffer_shrink(buffer);
 }
 
 void buffer_free(Buffer *buffer)
 {
+    trace_buffer_free(buffer->name ?: "unnamed", buffer->capacity);
     g_free(buffer->buffer);
+    g_free(buffer->name);
     buffer->offset = 0;
     buffer->capacity = 0;
     buffer->buffer = NULL;
+    buffer->name = NULL;
 }
 
 void buffer_append(Buffer *buffer, const void *data, size_t len)
@@ -62,4 +131,41 @@ void buffer_advance(Buffer *buffer, size_t len)
     memmove(buffer->buffer, buffer->buffer + len,
             (buffer->offset - len));
     buffer->offset -= len;
+    buffer_shrink(buffer);
+}
+
+void buffer_move_empty(Buffer *to, Buffer *from)
+{
+    trace_buffer_move_empty(to->name ?: "unnamed",
+                            from->offset,
+                            from->name ?: "unnamed");
+    assert(to->offset == 0);
+
+    g_free(to->buffer);
+    to->offset = from->offset;
+    to->capacity = from->capacity;
+    to->buffer = from->buffer;
+
+    from->offset = 0;
+    from->capacity = 0;
+    from->buffer = NULL;
+}
+
+void buffer_move(Buffer *to, Buffer *from)
+{
+    if (to->offset == 0) {
+        buffer_move_empty(to, from);
+        return;
+    }
+
+    trace_buffer_move(to->name ?: "unnamed",
+                      from->offset,
+                      from->name ?: "unnamed");
+    buffer_reserve(to, from->offset);
+    buffer_append(to, from->buffer, from->offset);
+
+    g_free(from->buffer);
+    from->offset = 0;
+    from->capacity = 0;
+    from->buffer = NULL;
 }