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Timothy Arceri authored
This code provides for an on-disk cache of objects. Objects are stored and retrieved via names that are arbitrary 20-byte sequences, (intended to be SHA-1 hashes of something identifying for the content). The directory used for the cache can be specified by means of environment variables in the following priority order: $MESA_GLSL_CACHE_DIR $XDG_CACHE_HOME/mesa <user-home-directory>/.cache/mesa By default the cache will be limited to a maximum size of 1GB. The environment variable: $MESA_GLSL_CACHE_MAX_SIZE can be set (at the time of GL context creation) to choose some other size. This variable is a number that can optionally be followed by 'K', 'M', or 'G' to select a size in kilobytes, megabytes, or gigabytes. By default, an unadorned value will be interpreted as gigabytes. The cache will be entirely disabled at runtime if the variable MESA_GLSL_CACHE_DISABLE is set at the time of GL context creation. Many thanks to Kristian Høgsberg <krh@bitplanet.net> for the initial implementation of code that led to this patch. In particular, the idea of using an mmapped file, (indexed by a portion of the SHA-1), for the efficent implementation of cache_has_key was entirely his idea. Kristian also provided some very helpful advice in discussions regarding various race conditions to be avoided in this code. Signed-off-by: Timothy Arceri <timothy.arceri@collabora.com> Reviewed-by: Eric Anholt <eric@anholt.net>
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