Accomodate GQL requests caching in code generator (#237)

* Accomodate GQL requests caching in code generator

* Add GQL API request queuing

packages/codegen/src/schema.ts

@@ -3,7 +3,7 @@
 //
 
 import assert from 'assert';
-import { GraphQLSchema, parse, printSchema, print } from 'graphql';
+import { GraphQLSchema, parse, printSchema, print, GraphQLDirective, GraphQLInt, GraphQLBoolean } from 'graphql';
 import { ObjectTypeComposer, ObjectTypeComposerDefinition, ObjectTypeComposerFieldConfigMapDefinition, SchemaComposer } from 'graphql-compose';
 import { Writable } from 'stream';
 import { utils } from 'ethers';
@@ -19,6 +19,7 @@ export class Schema {
     this._composer = new SchemaComposer();
     this._events = [];
 
+    this._addGQLCacheTypes();
     this._addBasicTypes();
   }
 
@@ -271,6 +272,28 @@ export class Schema {
     this._composer.addSchemaMustHaveType(typeComposer);
   }
 
+  _addGQLCacheTypes (): void {
+    // Create a enum type composer to add enum CacheControlScope in the schema composer.
+    const enumTypeComposer = this._composer.createEnumTC(`
+      enum CacheControlScope {
+        PUBLIC
+        PRIVATE
+      }
+    `);
+    this._composer.addSchemaMustHaveType(enumTypeComposer);
+
+    // Add the directive cacheControl in the schema composer.
+    this._composer.addDirective(new GraphQLDirective({
+      name: 'cacheControl',
+      locations: ['FIELD_DEFINITION', 'OBJECT', 'INTERFACE', 'UNION'],
+      args: {
+        maxAge: { type: GraphQLInt },
+        inheritMaxAge: { type: GraphQLBoolean },
+        scope: { type: enumTypeComposer.getType() }
+      }
+    }));
+  }
+
   /**
    * Adds types 'ResultEvent' and 'WatchedEvent' to the schema.
    */

packages/codegen/src/templates/config-template.handlebars

@@ -30,6 +30,19 @@
   # Use -1 for skipping check on block range.
   maxEventsBlockRange = 1000
 
+  # GQL cache settings
+  [server.gqlCache]
+    enabled = true
+
+    # Max in-memory cache size (in bytes) (default 8 MB)
+    # maxCacheSize
+
+    # GQL cache-control max-age settings (in seconds)
+    maxAge = 15
+    {{#if (subgraphPath)}}
+    timeTravelMaxAge = 86400 # 1 day
+    {{/if}}
+
 [metrics]
   host = "127.0.0.1"
   port = 9000

packages/codegen/src/templates/readme-template.handlebars

@@ -59,6 +59,18 @@
 
   * Edit the custom hook function `createStateCheckpoint` (triggered just before default and CLI checkpoint) in [hooks.ts](./src/hooks.ts) to save the state in a `checkpoint` `State` using the `Indexer` object.
 
+### GQL Caching
+
+To enable GQL requests caching:
+
+* Update the `server.gqlCache` config with required settings.
+
+* In the GQL [schema file](./src/schema.gql), use the `cacheControl` directive to apply cache hints at schema level.
+
+  * Eg. Set `inheritMaxAge` to true for non-scalar fields of a type.
+
+* In the GQL [resolvers file](./src/resolvers.ts), uncomment the `setGQLCacheHints()` calls in resolvers for required queries.
+
 ## Run
 
 * Run the watcher:

packages/codegen/src/templates/resolvers-template.handlebars

@@ -8,7 +8,7 @@ import debug from 'debug';
 import Decimal from 'decimal.js';
 import { GraphQLResolveInfo, GraphQLScalarType } from 'graphql';
 
-import { ValueResult, BlockHeight, gqlTotalQueryCount, gqlQueryCount, jsonBigIntStringReplacer, getResultState } from '@cerc-io/util';
+import { ValueResult, BlockHeight, gqlTotalQueryCount, gqlQueryCount, jsonBigIntStringReplacer, getResultState, setGQLCacheHints } from '@cerc-io/util';
 
 import { Indexer } from './indexer';
 import { EventWatcher } from './events';
@@ -22,6 +22,8 @@ const log = debug('vulcanize:resolver');
 export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatcher): Promise<any> => {
   assert(indexer);
 
+  const gqlCacheConfig = indexer.serverConfig.gqlCache;
+
   return {
     BigInt: new BigInt('bigInt'),
 
@@ -63,14 +65,22 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
 
     Query: {
       {{#each queries}}
-      {{this.name}}: (_: any, { blockHash, contractAddress
-      {{~#each this.params}}, {{this.name~}} {{/each}} }: { blockHash: string, contractAddress: string
-      {{~#each this.params}}, {{this.name}}: {{this.type~}} {{/each}} }): Promise<ValueResult> => {
+      {{this.name}}: (
+        _: any,
+        { blockHash, contractAddress
+        {{~#each this.params}}, {{this.name~}} {{/each}} }: { blockHash: string, contractAddress: string
+        {{~#each this.params}}, {{this.name}}: {{this.type~}} {{/each}} },
+        __: any,
+        info: GraphQLResolveInfo
+      ): Promise<ValueResult> => {
         log('{{this.name}}', blockHash, contractAddress
         {{~#each this.params}}, {{this.name~}} {{/each}});
         gqlTotalQueryCount.inc(1);
         gqlQueryCount.labels('{{this.name}}').inc(1);
 
+        // Set cache-control hints
+        // setGQLCacheHints(info, {}, gqlCacheConfig);
+
         return indexer.{{this.name}}(blockHash, contractAddress
         {{~#each this.params}}, {{this.name~}} {{/each}});
       },
@@ -79,7 +89,7 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
 
       {{~#each subgraphQueries}}
       {{this.queryName}}: async (
-         _: any,
+        _: any,
         { id, block = {} }: { id: string, block: BlockHeight },
         __: any,
         info: GraphQLResolveInfo
@@ -89,6 +99,9 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
         gqlQueryCount.labels('{{this.queryName}}').inc(1);
         assert(info.fieldNodes[0].selectionSet);
 
+        // Set cache-control hints
+        // setGQLCacheHints(info, block, gqlCacheConfig);
+
         return indexer.getSubgraphEntity({{this.entityName}}, id, block, info.fieldNodes[0].selectionSet.selections);
       },
 

packages/codegen/src/templates/server-template.handlebars

@@ -39,7 +39,7 @@ export const main = async (): Promise<any> => {
   const config: Config = await getConfig(argv.f);
   const { ethClient, ethProvider } = await initClients(config);
 
-  const { host, port, kind: watcherKind } = config.server;
+  const { kind: watcherKind } = config.server;
 
   const db = new Database(config.database);
   await db.init();
@@ -85,7 +85,7 @@ export const main = async (): Promise<any> => {
 
   // Create an Express app
   const app: Application = express();
-  const server = createAndStartServer(app, typeDefs, resolvers, { host, port });
+  const server = createAndStartServer(app, typeDefs, resolvers, config.server);
 
   startGQLMetricsServer(config);