[Mesa-dev] [PATCH 2/4] util/disk_cache: add struct cache_item_metadata

[Nicolai Hähnle]

On 15.08.2017 01:26, Timothy Arceri wrote:
> This will be used to store more information about the cache item
> in it's header. This information is intended for 3rd party and
> cache analysis use but can also be used for detecting the unlikely
> scenario of cache collisions.
> ---
>   src/util/disk_cache.h | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
> 
> diff --git a/src/util/disk_cache.h b/src/util/disk_cache.h
> index 9aade16a9e..d6d7609ffb 100644
> --- a/src/util/disk_cache.h
> +++ b/src/util/disk_cache.h
> @@ -34,20 +34,42 @@
>   
>   #ifdef __cplusplus
>   extern "C" {
>   #endif
>   
>   /* Size of cache keys in bytes. */
>   #define CACHE_KEY_SIZE 20
>   
>   typedef uint8_t cache_key[CACHE_KEY_SIZE];
>   
> +/* WARNING: 3rd party applications might be reading the cache item metadata.
> + * Do not change these values without making the change widely known.
> + * Please contact Valve developers and make them aware of this change.
> + */
> +#define CACHE_ITEM_TYPE_UNKNOWN  0x0
> +#define CACHE_ITEM_TYPE_GLSL     0x1
> +
> +typedef uint32_t cache_item_metadata_type;

Please don't do typedefs like that, they just obfuscate. If you don't 
want to just use uint32_t, I'd suggest to use an enum.

At a higher level, what is this actually good for? So I get Valve wants 
to parse something in the shader cache, but why / what for?

Cheers,
Nicolai


> +
> +struct cache_item_metadata {
> +   /**
> +    * The cache item type. This could be used to identify a GLSL cache item,
> +    * a certain type of IR (tgsi, nir, etc), or signal that it is the final
> +    * binary form of the shader.
> +    */
> +   cache_item_metadata_type type;
> +
> +   /** GLSL cache item metadata */
> +   cache_key *keys;   /* sha1 list of shaders that make up the cache item */
> +   uint32_t num_keys;
> +};
> +
>   struct disk_cache;
>   
>   static inline bool
>   disk_cache_get_function_timestamp(void *ptr, uint32_t* timestamp)
>   {
>   #ifdef ENABLE_SHADER_CACHE
>      Dl_info info;
>      struct stat st;
>      if (!dladdr(ptr, &info) || !info.dli_fname) {
>         return false;
> 


-- 
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Aber vergiss niemals, wie sie sein sollte.