66 lines
2.5 KiB
JavaScript
66 lines
2.5 KiB
JavaScript
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import path from "node:path";
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import fs from "node:fs/promises";
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import { BaseCache, getCacheKey, serializeGeneration, deserializeStoredGeneration, } from "@langchain/core/caches";
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/**
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* A cache that uses the local filesystem as the backing store.
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* This is useful for local development and testing. But it is not recommended for production use.
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*/
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export class LocalFileCache extends BaseCache {
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constructor(cacheDir) {
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super();
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Object.defineProperty(this, "cacheDir", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: void 0
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});
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this.cacheDir = cacheDir;
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}
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/**
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* Create a new cache backed by the local filesystem.
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* It ensures that the cache directory exists before returning.
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* @param cacheDir
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*/
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static async create(cacheDir) {
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if (!cacheDir) {
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// eslint-disable-next-line no-param-reassign
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cacheDir = await fs.mkdtemp("langchain-cache-");
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}
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else {
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// ensure the cache directory exists
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await fs.mkdir(cacheDir, { recursive: true });
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}
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return new LocalFileCache(cacheDir);
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}
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/**
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* Retrieves data from the cache. It constructs a cache key from the given
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* `prompt` and `llmKey`, and retrieves the corresponding value from the
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* cache files.
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* @param prompt The prompt used to construct the cache key.
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* @param llmKey The LLM key used to construct the cache key.
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* @returns An array of Generations if found, null otherwise.
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*/
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async lookup(prompt, llmKey) {
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const key = `${getCacheKey(prompt, llmKey)}.json`;
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try {
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const content = await fs.readFile(path.join(this.cacheDir, key));
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return JSON.parse(content.toString()).map(deserializeStoredGeneration);
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}
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catch {
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return null;
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}
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}
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/**
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* Updates the cache with new data. It constructs a cache key from the
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* given `prompt` and `llmKey`, and stores the `value` in a specific
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* file in the cache directory.
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* @param prompt The prompt used to construct the cache key.
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* @param llmKey The LLM key used to construct the cache key.
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* @param generations The value to be stored in the cache.
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*/
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async update(prompt, llmKey, generations) {
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const key = `${getCacheKey(prompt, llmKey)}.json`;
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await fs.writeFile(path.join(this.cacheDir, key), JSON.stringify(generations.map(serializeGeneration)));
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}
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}
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