From 9ee76b10fac4f1aeeec27b1576873d8c1057fd48 Mon Sep 17 00:00:00 2001
From: Matt Low <matt@mlow.ca>
Date: Fri, 5 Mar 2021 12:56:20 -0700
Subject: [PATCH] Add USE_WORKER_THREADS environment var

---
 src/graphql/sudoku.ts | 18 ++++++++++--------
 src/main.ts           | 22 ++++++++++++++++++++++
 src/sudoku/index.ts   |  5 ++---
 3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/graphql/sudoku.ts b/src/graphql/sudoku.ts
index 81f7373..3271699 100644
--- a/src/graphql/sudoku.ts
+++ b/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),
   },
 };
diff --git a/src/main.ts b/src/main.ts
index 7d6ebc1..a8b122b 100644
--- a/src/main.ts
+++ b/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(
diff --git a/src/sudoku/index.ts b/src/sudoku/index.ts
index 056c2f9..891094c 100644
--- a/src/sudoku/index.ts
+++ b/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(