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DISK_FORMAT_VERSION

micromegas::object_cache::foyer_backend

Constant DISK_FORMAT_VERSION 

Source 
pub const DISK_FORMAT_VERSION: u32 = 1; // 1u32
Expand description

On-disk format version for the foyer disk tier. The serialized value layout (CachedBlock’s Code impl) carries no self-describing version, so a layout change would otherwise misdecode entries recovered from a persisted store on restart. On startup the store directory is wiped iff the persisted marker does not match this constant.

BUMP THIS whenever CachedBlock’s Code encode/decode (or any on-disk layout foyer persists for us) changes.

History:

  • v1: CachedBlock = [i64 LE disk_write_ms][length-prefixed Bytes]. The unversioned predecessor layout was Bytes-only; upgrading onto a store it wrote is the crash this guard prevents.