[vlc-devel] [PATCH] cache_block: account alloc size instead of payload

[Francois Cartegnie]

Current block_cache accounts only payload data which
results in storing far more data, than the expected
STREAM_CACHE_SIZE limit, when the access allocs
larger blocks than payload.

Ex: UDP 2^16 (max MTU), dtv (20 * 128).
reading re-streamed rtsp allocates more than 300MB
before reaching the payload cache size.

OOM'ing client only depends on bw if a server sends
zero or one byte sized payload UDP (limit becoming ~12*256GB)

refs #16315, #14458, #16270
---
 modules/stream_filter/cache_block.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/modules/stream_filter/cache_block.c b/modules/stream_filter/cache_block.c
index dc31506..24f253a 100644
--- a/modules/stream_filter/cache_block.c
+++ b/modules/stream_filter/cache_block.c
@@ -72,7 +72,8 @@ struct stream_sys_t
     uint64_t     i_offset;       /* Offset for data in p_current */
     block_t     *p_current;     /* Current block */
 
-    uint64_t     i_size;         /* Total amount of data in the list */
+    uint64_t     i_alloc_size;   /* Total amount of allocated data in the list */
+    uint64_t     i_size;         /* Total amount of payload data in the list */
     block_t     *p_first;
     block_t    **pp_last;
 
@@ -102,18 +103,19 @@ static int AStreamRefillBlock(stream_t *s)
     stream_sys_t *sys = s->p_sys;
 
     /* Release data */
-    while (sys->i_size >= STREAM_CACHE_SIZE &&
+    while (sys->i_alloc_size >= STREAM_CACHE_SIZE &&
            sys->p_first != sys->p_current)
     {
         block_t *b = sys->p_first;
 
         sys->i_start += b->i_buffer;
         sys->i_size  -= b->i_buffer;
+        sys->i_alloc_size -= b->i_size;
         sys->p_first  = b->p_next;
 
         block_Release(b);
     }
-    if (sys->i_size >= STREAM_CACHE_SIZE &&
+    if (sys->i_alloc_size >= STREAM_CACHE_SIZE &&
         sys->p_current == sys->p_first &&
         sys->p_current->p_next)    /* At least 2 packets */
     {
@@ -144,6 +146,7 @@ static int AStreamRefillBlock(stream_t *s)
     {
         /* Append the block */
         sys->i_size += b->i_buffer;
+        sys->i_alloc_size += b->i_size;
         *sys->pp_last = b;
         sys->pp_last = &b->p_next;
 
@@ -203,6 +206,7 @@ static void AStreamPrebufferBlock(stream_t *s)
         {
             /* Append the block */
             sys->i_size += b->i_buffer;
+            sys->i_alloc_size += b->i_size;
             *sys->pp_last = b;
             sys->pp_last = &b->p_next;
 
@@ -472,6 +476,7 @@ static int Open(vlc_object_t *obj)
     sys->i_offset = 0;
     sys->p_current = NULL;
     sys->i_size = 0;
+    sys->i_alloc_size = 0;
     sys->p_first = NULL;
     sys->pp_last = &sys->p_first;
 
-- 
2.5.0