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/*
* Copyright (c) 2011-Present, Redis Ltd.
* All rights reserved.
*
* Licensed under your choice of (a) the Redis Source Available License 2.0
* (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
* GNU Affero General Public License v3 (AGPLv3).
*
* estore.h -- Expiration Store implementation
*
* ESTORE (Expiration Store)
* =========================
*
* Index-based expiration store implementation. Similar to kvstore, but built
* on top of ebuckets instead of dict. Items stored in estore must embed an
* ExpireMeta, enabling efficient active-expiration.
*
* Estore is currently used to manage "subexpiry" only for hash objects with
* field-level expiration (HFE). Each hash with HFE is registered in estore
* with the earliest expiration time among its fields.
*
* USAGE IN REDIS
* ==============
* This implementation is used to efficiently track hash objects that have
* field-level expiration (HFE):
* - Each hash with HFE is registered with its earliest field expiration time
* - Enables efficient active expiration of hash fields
* - Uses Fenwick tree for efficient iteration through non-empty buckets
* - Supports cluster mode with per-slot buckets
*
* IMPLEMENTATION NOTES
* ====================
* - Built on top of ebuckets data structure for expiration management
* - Uses Fenwick tree to track cumulative item counts across buckets
* - Supports both single bucket (standalone) and multiple buckets (cluster) modes
* - All operations have O(log n) time complexity for bucket selection
*
* STRUCTURE
* =========
* - ebArray: Array of ebuckets (one per slot in cluster mode, or just one)
* - buckets_sizes: Fenwick tree tracking cumulative counts for efficient iteration
* - bucket_type: EbucketsType defining callbacks for the stored items
*/
#ifndef __ESTORE_H
#define __ESTORE_H
#include "ebuckets.h"
#include "fwtree.h"
/* Forward declaration of the estore structure */
typedef struct _estore estore;
/* Estore API */
estore *estoreCreate(EbucketsType *type, int num_buckets_bits);
void estoreEmpty(estore *es);
int estoreIsEmpty(estore *es);
void estoreRelease(estore *es);
void estoreActiveExpire(estore *es, int eidx, ExpireInfo *info);
uint64_t estoreRemove(estore *es, int eidx, eItem item);
void estoreAdd(estore *es, int eidx, eItem item, uint64_t when);
void estoreUpdate(estore *es, int eidx, eItem item, uint64_t when);
uint64_t estoreSize(estore *es);
ebuckets *estoreGetBuckets(estore *es, int eidx);
int estoreGetFirstNonEmptyBucket(estore *es);
int estoreGetNextNonEmptyBucket(estore *es, int eidx);
void estoreMoveEbuckets(estore *src, estore *dst, int eidx);
/* Hash-specific function to get ExpireMeta from a hash kvobj.
* Once we shall have another data-type with subexpiry, we should refactor
* ExpireMeta to optionally reside as part of kvobj struct */
ExpireMeta *hashGetExpireMeta(const eItem kvobjHash);
#ifdef REDIS_TEST
int estoreTest(int argc, char *argv[], int flags);
#endif
#endif /* __ESTORE_H */
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