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implement a multi-tiered cache for aws
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‎packages/open-next/src/overrides/incrementalCache/multi-tier-ddb-s3.ts‎

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import type { CacheValue, IncrementalCache } from "types/overrides";
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import S3Cache, { getAwsClient } from "./s3-lite";
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import { customFetchClient } from "utils/fetch";
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import { debug } from "../../adapters/logger";
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// TTL for the local cache in milliseconds
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const localCacheTTL = process.env.OPEN_NEXT_LOCAL_CACHE_TTL
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? Number.parseInt(process.env.OPEN_NEXT_LOCAL_CACHE_TTL)
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: 0;
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// Maximum size of the local cache in nb of entries
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const maxCacheSize = process.env.OPEN_NEXT_LOCAL_CACHE_SIZE
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? Number.parseInt(process.env.OPEN_NEXT_LOCAL_CACHE_SIZE)
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: 1000;
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class LRUCache {
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private cache: Map<
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string,
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{
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value: CacheValue<boolean>;
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lastModified: number;
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}
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> = new Map();
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private maxSize: number;
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constructor(maxSize: number) {
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this.maxSize = maxSize;
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}
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// isFetch is not used here, only used for typing
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get<T extends boolean = false>(key: string, isFetch?: T) {
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return this.cache.get(key) as {
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value: CacheValue<T>;
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lastModified: number;
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};
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}
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set(key: string, value: any) {
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if (this.cache.size >= this.maxSize) {
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const firstKey = this.cache.keys().next().value;
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if (firstKey) {
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this.cache.delete(firstKey);
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}
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}
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this.cache.set(key, value);
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}
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delete(key: string) {
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this.cache.delete(key);
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}
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}
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const localCache = new LRUCache(maxCacheSize);
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const awsFetch = (body: RequestInit["body"], type: "get" | "set" = "get") => {
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const { CACHE_BUCKET_REGION } = process.env;
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const client = getAwsClient();
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return customFetchClient(client)(
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`https://dynamodb.${CACHE_BUCKET_REGION}.amazonaws.com`,
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{
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method: "POST",
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headers: {
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"Content-Type": "application/x-amz-json-1.0",
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"X-Amz-Target": `DynamoDB_20120810.${
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type === "get" ? "GetItem" : "PutItem"
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}`,
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},
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body,
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},
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);
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};
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const buildDynamoKey = (key: string) => {
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const { NEXT_BUILD_ID } = process.env;
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return `__meta_${NEXT_BUILD_ID}_${key}`;
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};
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/**
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* This cache implementation uses a multi-tier cache with a local cache, a DynamoDB metadata cache and an S3 cache.
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* It uses the same DynamoDB table as the default tag cache and the same S3 bucket as the default incremental cache.
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* It will first check the local cache.
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* If the local cache is expired, it will check the DynamoDB metadata cache to see if the local cache is still valid.
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* Lastly it will check the S3 cache.
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*/
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const multiTierCache: IncrementalCache = {
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name: "multi-tier-ddb-s3",
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async get(key, isFetch) {
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// First we check the local cache
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const localCacheEntry = localCache.get(key, isFetch);
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if (localCacheEntry) {
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if (Date.now() - localCacheEntry.lastModified < localCacheTTL) {
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debug("Using local cache without checking ddb");
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return localCacheEntry;
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}
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try {
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// Here we'll check ddb metadata to see if the local cache is still valid
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const { CACHE_DYNAMO_TABLE } = process.env;
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const result = await awsFetch(
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JSON.stringify({
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TableName: CACHE_DYNAMO_TABLE,
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Key: {
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path: { S: buildDynamoKey(key) },
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tag: { S: buildDynamoKey(key) },
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},
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}),
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);
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if (result.status === 200) {
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const data = await result.json();
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const hasBeenDeleted = data.Item?.deleted?.BOOL;
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if (hasBeenDeleted) {
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localCache.delete(key);
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return { value: undefined, lastModified: 0 };
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}
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// If the metadata is older than the local cache, we can use the local cache
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// If it's not found we assume that no write has been done yet and we can use the local cache
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const lastModified = data.Item?.revalidatedAt?.N
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? Number.parseInt(data.Item.revalidatedAt.N)
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: 0;
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if (lastModified <= localCacheEntry.lastModified) {
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debug("Using local cache after checking ddb");
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return localCacheEntry;
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}
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}
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} catch (e) {
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debug("Failed to get metadata from ddb", e);
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}
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}
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const result = await S3Cache.get(key, isFetch);
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if (result.value) {
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localCache.set(key, {
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value: result.value,
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lastModified: result.lastModified ?? Date.now(),
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});
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}
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return result;
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},
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async set(key, value, isFetch) {
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const revalidatedAt = Date.now();
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await S3Cache.set(key, value, isFetch);
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await awsFetch(
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JSON.stringify({
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TableName: process.env.CACHE_DYNAMO_TABLE,
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Item: {
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tag: { S: buildDynamoKey(key) },
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path: { S: buildDynamoKey(key) },
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revalidatedAt: { N: String(revalidatedAt) },
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},
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}),
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"set",
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);
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localCache.set(key, {
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value,
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lastModified: revalidatedAt,
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});
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},
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async delete(key) {
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await S3Cache.delete(key);
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await awsFetch(
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JSON.stringify({
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TableName: process.env.CACHE_DYNAMO_TABLE,
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Item: {
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tag: { S: buildDynamoKey(key) },
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path: { S: buildDynamoKey(key) },
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deleted: { BOOL: true },
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},
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}),
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"set",
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);
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localCache.delete(key);
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},
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};
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export default multiTierCache;

‎packages/open-next/src/overrides/incrementalCache/s3-lite.ts‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@ import { parseNumberFromEnv } from "../../adapters/util";
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let awsClient: AwsClient | null = null;
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const getAwsClient = () => {
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export const getAwsClient = () => {
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const { CACHE_BUCKET_REGION } = process.env;
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if (awsClient) {
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return awsClient;

‎packages/open-next/src/types/open-next.ts‎

Lines changed: 6 additions & 1 deletion
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@@ -136,7 +136,12 @@ export interface MiddlewareResult
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export type IncludedQueue = "sqs" | "sqs-lite" | "direct" | "dummy";
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export type IncludedIncrementalCache = "s3" | "s3-lite" | "fs-dev" | "dummy";
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export type IncludedIncrementalCache =
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| "s3"
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| "s3-lite"
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| "multi-tier-ddb-s3"
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| "fs-dev"
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| "dummy";
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export type IncludedTagCache =
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| "dynamodb"

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