/**
 * Storage Tier Interface
 * Defines the contract for all storage tier implementations (RAM, SSD, DB)
 * Requirements: 2.1, 2.2, 2.3, 2.4
 */
import { KeyMetadata } from '../types/index.js';
/**
 * Configuration options for initializing a storage tier
 */
export interface TierConfig {
    /** Maximum capacity in bytes for this tier */
    capacityBytes: number;
    /** Optional path for persistent storage (SSD/DB tiers) */
    storagePath?: string;
    /** Optional connection string for database tier */
    connectionString?: string;
}
/**
 * StorageTier interface defines the contract for all storage tier implementations.
 * Each tier (RAM, SSD, DB) must implement this interface to provide consistent
 * access patterns across the tiered cache system.
 */
export interface StorageTier {
    /**
     * Retrieve a value by key
     * @param key - The cache key to retrieve
     * @returns The value as a Buffer, or null if not found
     */
    get(key: string): Promise<Buffer | null>;
    /**
     * Store a key-value pair with metadata
     * @param key - The cache key
     * @param value - The value to store
     * @param metadata - Associated metadata (expiration, creation time, tier)
     */
    set(key: string, value: Buffer, metadata: KeyMetadata): Promise<void>;
    /**
     * Delete a key from the tier
     * @param key - The cache key to delete
     * @returns true if the key was deleted, false if it didn't exist
     */
    delete(key: string): Promise<boolean>;
    /**
     * Check if a key exists in this tier
     * @param key - The cache key to check
     * @returns true if the key exists, false otherwise
     */
    exists(key: string): Promise<boolean>;
    /**
     * Retrieve multiple values by keys (bulk operation)
     * @param keys - Array of cache keys to retrieve
     * @returns Map of key to value for keys that exist
     */
    mget(keys: string[]): Promise<Map<string, Buffer>>;
    /**
     * Store multiple key-value pairs (bulk operation)
     * @param entries - Map of key to value
     * @param metadata - Metadata to apply to all entries
     */
    mset(entries: Map<string, Buffer>, metadata: KeyMetadata): Promise<void>;
    /**
     * Get the current used bytes in this tier
     * @returns Number of bytes currently used
     */
    getUsedBytes(): number;
    /**
     * Get the maximum capacity in bytes for this tier
     * @returns Maximum capacity in bytes
     */
    getCapacityBytes(): number;
    /**
     * Iterate over keys in this tier, optionally filtered by pattern
     * @param pattern - Optional glob pattern to filter keys
     * @returns AsyncIterator yielding matching keys
     */
    keys(pattern?: string): AsyncIterableIterator<string>;
    /**
     * Initialize and open the storage tier
     * @param config - Configuration options for the tier
     */
    open(config: TierConfig): Promise<void>;
    /**
     * Close the storage tier and release resources
     */
    close(): Promise<void>;
    /**
     * Flush any pending writes to persistent storage
     */
    flush(): Promise<void>;
}
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