/**
 * Core type definitions for Smart Tiered Cache
 * Requirements: 2.1, 2.2, 2.3
 */
/**
 * Storage tier types representing the three-tier architecture.
 * - 'ram': Fastest tier for hot (frequently accessed) data
 * - 'ssd': Intermediate tier using RocksDB for warm data
 * - 'db': Persistent tier for cold (rarely accessed) data
 */
export type Tier = 'ram' | 'ssd' | 'db';
/**
 * Represents a cached value with its associated metadata.
 * Used when retrieving data from the cache engine.
 */
export interface CacheValue {
    /** The raw data stored in the cache */
    data: Buffer;
    /** The storage tier where this value currently resides */
    tier: Tier;
    /** Unix timestamp (ms) when this value expires, undefined if no expiration */
    expiresAt?: number;
}
/**
 * Metadata associated with a cached key.
 * Used for tracking key lifecycle and tier placement.
 */
export interface KeyMetadata {
    /** Unix timestamp (ms) when this key expires, undefined if no expiration */
    expiresAt?: number;
    /** Unix timestamp (ms) when this key was created */
    createdAt: number;
    /** The storage tier where this key currently resides */
    tier: Tier;
}
/**
 * Entry in the unified key index for O(1) tier location lookup.
 * Requirement 2.7: Maintain a unified key index across all tiers
 */
export interface KeyIndexEntry {
    /** The cache key */
    key: string;
    /** The storage tier where this key currently resides */
    tier: Tier;
    /** Size of the value in bytes */
    sizeBytes: number;
    /** Unix timestamp (ms) when this key expires, null if no expiration */
    expiresAt: number | null;
    /** Unix timestamp (ms) when this key was created */
    createdAt: number;
}
/**
 * Options for SET operations.
 * Supports TTL and conditional set operations (NX/XX).
 */
export interface SetOptions {
    /** Time-to-live in seconds */
    ttlSeconds?: number;
    /** Only set if key does not exist (SET NX) */
    nx?: boolean;
    /** Only set if key already exists (SET XX) */
    xx?: boolean;
}
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