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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2023 Red Hat
*/
#ifndef UDS_SPARSE_CACHE_H
#define UDS_SPARSE_CACHE_H
#include "geometry.h"
#include "indexer.h"
/*
* The sparse cache is a cache of entire chapter indexes from sparse chapters used for searching
* for names after all other search paths have failed. It contains only complete chapter indexes;
* record pages from sparse chapters and single index pages used for resolving hooks are kept in
* the regular page cache in the volume.
*
* The most important property of this cache is the absence of synchronization for read operations.
* Safe concurrent access to the cache by the zone threads is controlled by the triage queue and
* the barrier requests it issues to the zone queues. The set of cached chapters does not and must
* not change between the carefully coordinated calls to uds_update_sparse_cache() from the zone
* threads. Outside of updates, every zone will get the same result when calling
* uds_sparse_cache_contains() as every other zone.
*/
struct index_zone;
struct sparse_cache;
int __must_check uds_make_sparse_cache(const struct index_geometry *geometry,
unsigned int capacity, unsigned int zone_count,
struct sparse_cache **cache_ptr);
void uds_free_sparse_cache(struct sparse_cache *cache);
bool uds_sparse_cache_contains(struct sparse_cache *cache, u64 virtual_chapter,
unsigned int zone_number);
int __must_check uds_update_sparse_cache(struct index_zone *zone, u64 virtual_chapter);
void uds_invalidate_sparse_cache(struct sparse_cache *cache);
int __must_check uds_search_sparse_cache(struct index_zone *zone,
const struct uds_record_name *name,
u64 *virtual_chapter_ptr, u16 *record_page_ptr);
#endif /* UDS_SPARSE_CACHE_H */
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