Add config for GQL requests cache (#228)

* Add config and a method to set cache control settings for GQL requests

* Add option for max size in GQL cache config

* Fix failing tests

packages/util/src/config.ts

@@ -29,6 +29,13 @@ export interface JobQueueConfig {
   prefetchBlockCount: number;
 }
 
+export interface GQLCacheConfig {
+  enabled: boolean;
+  maxCacheSize?: number;
+  maxAge: number;
+  timeTravelMaxAge: number;
+}
+
 export interface ServerConfig {
   host: string;
   port: number;
@@ -54,6 +61,9 @@ export interface ServerConfig {
 
   // Boolean to load GQL query nested entity relations sequentially.
   loadRelationsSequential: boolean;
+
+  // GQL cache-control max-age settings (in seconds)
+  gqlCache: GQLCacheConfig
 }
 
 export interface UpstreamConfig {

packages/util/src/constants.ts

@@ -23,3 +23,5 @@ export const UNKNOWN_EVENT_NAME = '__unknown__';
 
 export const KIND_ACTIVE = 'active';
 export const KIND_LAZY = 'lazy';
+
+export const DEFAULT_MAX_GQL_CACHE_SIZE = Math.pow(2, 20) * 8; // 8 MB

packages/util/src/misc.ts

@@ -9,17 +9,20 @@ import { hideBin } from 'yargs/helpers';
 import { utils, providers } from 'ethers';
 import JSONbig from 'json-bigint';
 import Decimal from 'decimal.js';
+import { GraphQLResolveInfo } from 'graphql';
+import _ from 'lodash';
 
 import { EthClient } from '@cerc-io/ipld-eth-client';
 
 import { DEFAULT_CONFIG_PATH } from './constants';
-import { Config } from './config';
+import { GQLCacheConfig, Config } from './config';
 import { JobQueue } from './job-queue';
 import { GraphDecimal } from './graph-decimal';
 import * as EthDecoder from './eth';
 import { getCachedBlockSize } from './block-size-cache';
 import { ResultEvent } from './indexer';
 import { EventInterface } from './types';
+import { BlockHeight } from './database';
 
 const JSONbigNative = JSONbig({ useNativeBigInt: true });
 
@@ -287,3 +290,15 @@ export const getResultEvent = (event: EventInterface): ResultEvent => {
     proof: JSON.parse(event.proof)
   };
 };
+
+export const setGQLCacheHints = (info: GraphQLResolveInfo, block: BlockHeight, gqlCache: GQLCacheConfig): void => {
+  if (!gqlCache || !gqlCache.enabled) {
+    return;
+  }
+
+  assert(gqlCache.maxAge, 'Missing server gqlCache.maxAge');
+  assert(gqlCache.timeTravelMaxAge, 'Missing server gqlCache.timeTravelMaxAge');
+
+  const maxAge = _.isEmpty(block) ? gqlCache.maxAge : gqlCache.timeTravelMaxAge;
+  info.cacheControl.setCacheHint({ maxAge });
+};