Add USE_WORKER_THREADS environment var

src/graphql/sudoku.ts

@@ -1,10 +1,5 @@
 import { gql } from "../mods.js";
-import {
-  solve,
-  generate,
-  GenerateArguments,
-  SolveArguments,
-} from "../sudoku/index.js";
+import { Sudoku, GenerateArguments, SolveArguments } from "../sudoku/index.js";
 
 export const typeDefs = gql`
   """
@@ -33,9 +28,16 @@ export const typeDefs = gql`
   }
 `;
 
+interface SudokuFuncs {
+  solve(args: SolveArguments): Promise<Sudoku> | Sudoku;
+  generate(args: GenerateArguments): Promise<Sudoku> | Sudoku;
+}
+
 export const resolvers = {
   Query: {
-    generate: (obj: any, args: GenerateArguments) => generate(args),
-    solve: (obj: any, args: SolveArguments) => solve(args),
+    generate: (obj: any, args: GenerateArguments, ctx: SudokuFuncs) =>
+      ctx.generate(args),
+    solve: (obj: any, args: SolveArguments, ctx: SudokuFuncs) =>
+      ctx.solve(args),
   },
 };

src/main.ts

@@ -1,6 +1,13 @@
 import { Application, bodyParser } from "./mods.js";
 import { applyGraphQL } from "./graphql.js";
 import { typeDefs, resolvers } from "./graphql/index.js";
+import {
+  initializeWorkers,
+  solve,
+  generate,
+  solveSync,
+  generateSync,
+} from "./sudoku/index.js";
 import stoppable from "stoppable";
 
 import cors from "@koa/cors";
@@ -31,10 +38,25 @@ async function main() {
     );
   });
 
+  let sudokuFuncs: any;
+  if (process.env.USE_WORKER_THREADS) {
+    initializeWorkers();
+    sudokuFuncs = {
+      solve,
+      generate,
+    };
+  } else {
+    sudokuFuncs = {
+      solve: solveSync,
+      generate: generateSync,
+    };
+  }
+
   applyGraphQL({
     app,
     typeDefs: typeDefs,
     resolvers: resolvers,
+    context: () => sudokuFuncs,
   });
 
   runtime.server = stoppable(

src/sudoku/index.ts

@@ -49,13 +49,12 @@ function spawnWorker() {
   );
 }
 
-function initialize() {
+export function initializeWorkers() {
   console.log(`Starting ${WORKERS} worker threads`);
   for (let n = 0; n < WORKERS; n++) {
     spawnWorker();
   }
 }
-initialize();
 
 function pickWorker() {
   const proxy = available.pop();
@@ -165,7 +164,7 @@ export function solveSync({
   regionWidth,
   regionHeight,
   cells,
-}: SolveArguments) {
+}: SolveArguments): Sudoku {
   const size = (regionWidth * regionHeight) ** 2;
   if (size !== cells.length) {
     throw new Error(