[Spice-devel] [spice-gtk PATCH] This adds reference counting to cached images.

[Marc-André Lureau]

Hi

----- Original Message -----
> Windows guests with multi-monitors will often send down the same image
> via different channels. If these instances are not counted, one channel
> can delete an image before all the rest of the channels are finished with
> it. In this case, the client will hang.
> 

This looks like a change in the protocol.
- an image with an existing id will no longer replace it
- there is extra data being sent by the server
- this looks like a server bug to me if an image is being removed and later referenced

Could this be addressed on server side to not change the current behaviour and avoid unnecessary data being sent to the client?

> Addresses bug: https://bugzilla.redhat.com/show_bug.cgi?id=1194354
> ---
> src/spice-channel-cache.h | 60
> ++++++++++++++++++++++++++++++++++++-----------
> src/spice-session.c | 2 +-
> 2 files changed, 47 insertions(+), 15 deletions(-)
> 
> diff --git a/src/spice-channel-cache.h b/src/spice-channel-cache.h
> index 17775e6..968e661 100644
> --- a/src/spice-channel-cache.h
> +++ b/src/spice-channel-cache.h
> @@ -27,15 +27,20 @@ G_BEGIN_DECLS
> typedef struct display_cache_item {
> guint64 id;
> gboolean lossy;
> + uint32_t ref_count;
> } display_cache_item;
> 
> -typedef GHashTable display_cache;
> +typedef struct display_cache {
> + GHashTable *table;
> + gboolean ref_counted;
> +}display_cache;
> 
> static inline display_cache_item* cache_item_new(guint64 id, gboolean lossy)
> {
> display_cache_item *self = g_slice_new(display_cache_item);
> self->id = id;
> self->lossy = lossy;
> + self->ref_count = 1;
> return self;
> }
> 
> @@ -46,18 +51,24 @@ static inline void
> cache_item_free(display_cache_item *self)
> 
> static inline display_cache* cache_new(GDestroyNotify value_destroy)
> {
> - GHashTable* self;
> -
> - self = g_hash_table_new_full(g_int64_hash, g_int64_equal,
> - (GDestroyNotify)cache_item_free,
> - value_destroy);
> -
> + display_cache * self = g_slice_new(display_cache);
> + self->table = g_hash_table_new_full(g_int64_hash, g_int64_equal,
> + (GDestroyNotify) cache_item_free,
> + value_destroy);
> + self->ref_counted = FALSE;
> return self;
> }
> 
> +static inline display_cache * cache_image_new(GDestroyNotify value_destroy)
> +{
> + display_cache * self = cache_new(value_destroy);
> + self->ref_counted = TRUE;
> + return self;
> +};
> +
> static inline gpointer cache_find(display_cache *cache, uint64_t id)
> {
> - return g_hash_table_lookup(cache, &id);
> + return g_hash_table_lookup(cache->table, &id);
> }
> 
> static inline gpointer cache_find_lossy(display_cache *cache, uint64_t
> id, gboolean *lossy)
> @@ -65,7 +76,7 @@ static inline gpointer cache_find_lossy(display_cache
> *cache, uint64_t id, gbool
> gpointer value;
> display_cache_item *item;
> 
> - if (!g_hash_table_lookup_extended(cache, &id, (gpointer*)&item, &value))
> + if (!g_hash_table_lookup_extended(cache->table, &id, (gpointer*)&item,
> &value))
> return NULL;
> 
> *lossy = item->lossy;
> @@ -77,8 +88,17 @@ static inline void cache_add_lossy(display_cache
> *cache, uint64_t id,
> gpointer value, gboolean lossy)
> {
> display_cache_item *item = cache_item_new(id, lossy);
> -
> - g_hash_table_replace(cache, item, value);
> + display_cache_item *current_item;
> + gpointer current_image;
> +
> + //If image is currently in the table add its reference count before
> replacing it
> + if(cache->ref_counted) {
> + if(g_hash_table_lookup_extended(cache->table, &id, (gpointer*) ¤t_item,
> + (gpointer*) ¤t_image)) {
> + item->ref_count = current_item->ref_count + 1;
> + }
> + }
> + g_hash_table_replace(cache->table, item, value);
> }
> 
> static inline void cache_add(display_cache *cache, uint64_t id, gpointer
> value)
> @@ -88,17 +108,29 @@ static inline void cache_add(display_cache *cache,
> uint64_t id, gpointer value)
> 
> static inline gboolean cache_remove(display_cache *cache, uint64_t id)
> {
> - return g_hash_table_remove(cache, &id);
> + display_cache_item * item;
> + gpointer value;
> +
> + if( g_hash_table_lookup_extended(cache->table, &id, (gpointer*) &item,
> &value)) {
> + --item->ref_count;
> + if(!cache->ref_counted || !item->ref_count ) {
> + return g_hash_table_remove(cache->table, &id);
> + }
> + }
> + else {
> + return FALSE;
> + }
> + return TRUE;
> }
> 
> static inline void cache_clear(display_cache *cache)
> {
> - g_hash_table_remove_all(cache);
> + g_hash_table_remove_all(cache->table);
> }
> 
> static inline void cache_unref(display_cache *cache)
> {
> - g_hash_table_unref(cache);
> + g_hash_table_unref(cache->table);
> }
> 
> G_END_DECLS
> diff --git a/src/spice-session.c b/src/spice-session.c
> index 778d82a..a252448 100644
> --- a/src/spice-session.c
> +++ b/src/spice-session.c
> @@ -257,7 +257,7 @@ static void spice_session_init(SpiceSession *session)
> g_free(channels);
> 
> ring_init(&s->channels);
> - s->images = cache_new((GDestroyNotify)pixman_image_unref);
> + s->images = cache_image_new((GDestroyNotify)pixman_image_unref);
> s->glz_window = glz_decoder_window_new();
> update_proxy(session, NULL);
> }
> --
> 1.9.5.msysgit.0
> 
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