import { routes } from "@lodestar/api";
import { CachedBeaconStateAllForks } from "@lodestar/state-transition";
import { Epoch, RootHex, phase0 } from "@lodestar/types";
export type CheckpointHex = {
    epoch: Epoch;
    rootHex: RootHex;
};
/**
 * Lodestar currently keeps two state caches around.
 *
 * 1. BlockStateCache is keyed by state root, and intended to keep extremely recent states around (eg: post states from the latest blocks)
 *    These states are most likely to be useful for state transition of new blocks.
 *
 * 2. CheckpointStateCache is keyed by checkpoint, and intended to keep states which have just undergone an epoch transition.
 *    These states are useful for gossip verification and for avoiding an epoch transition during state transition of first-in-epoch blocks
 */
/**
 * Store up to n recent block states.
 *
 * The cache key is state root
 */
export interface BlockStateCache {
    get(rootHex: RootHex): CachedBeaconStateAllForks | null;
    add(item: CachedBeaconStateAllForks): void;
    setHeadState(item: CachedBeaconStateAllForks | null): void;
    /**
     * Get a seed state for state reload.
     */
    getSeedState(): CachedBeaconStateAllForks;
    clear(): void;
    size: number;
    prune(headStateRootHex: RootHex): void;
    deleteAllBeforeEpoch(finalizedEpoch: Epoch): void;
    dumpSummary(): routes.lodestar.StateCacheItem[];
    /** Expose beacon states stored in cache. Use with caution */
    getStates(): IterableIterator<CachedBeaconStateAllForks>;
}
/**
 * Store checkpoint states to preserve epoch transition, this helps lodestar run exactly 1 epoch transition per epoch in normal network conditions.
 *
 * There are 2 types of checkpoint states:
 *
 * - Previous Root Checkpoint State: where root is from previous epoch, this is added when we prepare for next slot,
 * or to validate gossip block
 * ```
 *        epoch:       (n-2)   (n-1)     n     (n+1)
 *               |-------|-------|-------|-------|
 *        root     ---------------------^
 * ```
 *
 * - Current Root Checkpoint State: this is added when we process block slot 0 of epoch n, note that this block could
 * be skipped so we don't always have this checkpoint state
 * ```
 *        epoch:       (n-2)   (n-1)     n     (n+1)
 *               |-------|-------|-------|-------|
 *        root      ---------------------^
 * ```
 */
export interface CheckpointStateCache {
    init?: () => Promise<void>;
    getOrReload(cp: CheckpointHex): Promise<CachedBeaconStateAllForks | null>;
    getStateOrBytes(cp: CheckpointHex): Promise<CachedBeaconStateAllForks | Uint8Array | null>;
    get(cpOrKey: CheckpointHex | string): CachedBeaconStateAllForks | null;
    add(cp: phase0.Checkpoint, state: CachedBeaconStateAllForks): void;
    getLatest(rootHex: RootHex, maxEpoch: Epoch): CachedBeaconStateAllForks | null;
    getOrReloadLatest(rootHex: RootHex, maxEpoch: Epoch): Promise<CachedBeaconStateAllForks | null>;
    updatePreComputedCheckpoint(rootHex: RootHex, epoch: Epoch): number | null;
    prune(finalizedEpoch: Epoch, justifiedEpoch: Epoch): void;
    pruneFinalized(finalizedEpoch: Epoch): void;
    processState(blockRootHex: RootHex, state: CachedBeaconStateAllForks): Promise<number>;
    clear(): void;
    dumpSummary(): routes.lodestar.StateCacheItem[];
    /** Expose beacon states stored in cache. Use with caution */
    getStates(): IterableIterator<CachedBeaconStateAllForks>;
}
export declare enum CacheItemType {
    persisted = "persisted",
    inMemory = "in-memory"
}
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