llmRedis.js

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// llmRedis.js - Redis-backed LLM utilities for llama.cpp
const Redis = require('ioredis');
const crypto = require('crypto');
const redisConfig = require('../config/redis');
const redis = new Redis(redisConfig);
 
/**
 * Generate SHA-256 hash of text.
 * @param {string} text - Text to hash
 * @returns {string} Hex-encoded hash
 */
function hash(text) {
  return crypto.createHash('sha256').update(text).digest('hex');
}
 
/**
 * Get cached LLM result from Redis.
 * @param {string} type - LLM operation type (e.g., 'summarize', 'classify')
 * @param {string} text - Input text
 * @returns {Promise<string|null>} Cached result or null
 */
async function getCachedLLMResult(type, text) {
  const key = `llm:${type}:${hash(text)}`;
  return await redis.get(key);
}
 
/**
 * Set cached LLM result in Redis.
 * @param {string} type - LLM operation type
 * @param {string} text - Input text
 * @param {string} result - LLM result to cache
 * @param {number} [ttl] - Time to live in seconds (default: 604800 = 7 days)
 * @returns {Promise<void>}
 */
async function setCachedLLMResult(type, text, result, ttl = 604800) {
  const key = `llm:${type}:${hash(text)}`;
  await redis.set(key, result, 'EX', ttl);
}
 
/**
 * Check rate limit for tenant.
 * @param {number} tenantId - Tenant ID
 * @param {number} [limit] - Maximum requests allowed (default: 20)
 * @param {number} [window] - Time window in seconds (default: 60)
 * @returns {Promise<boolean>} True if rate limit exceeded
 */
async function rateLimit(tenantId, limit = 20, window = 60) {
  const key = `llm:rate:${tenantId}`;
  const count = await redis.incr(key);
  if (count === 1) await redis.expire(key, window);
  return count > limit;
}
 
/**
 * Acquire lock for document processing.
 * @param {string} docId - Document ID
 * @param {number} [ttl] - Lock TTL in seconds (default: 3)
 * @returns {Promise<boolean>} True if lock acquired
 */
async function acquireLock(docId, ttl = 3) {
  const key = `llm:lock:${docId}`;
  const lock = await redis.set(key, 1, 'NX', 'EX', ttl);
  return !!lock;
}
 
module.exports = {
  getCachedLLMResult,
  setCachedLLMResult,
  rateLimit,
  acquireLock,
};