config: make I/O operations synchronous

app/server/lib/config.ts

@@ -2,9 +2,9 @@ import * as fse from "fs-extra";
 
 // Export dependencies for stubbing in tests.
 export const Deps = {
-  readFile: fse.readFile,
+  readFile: fse.readFileSync,
   writeFile: fse.writeFile,
-  pathExists: fse.pathExists,
+  pathExists: fse.pathExistsSync,
 };
 
 /**
@@ -56,15 +56,15 @@ export class FileConfig<FileContents> {
    * @param validator - Validates the contents are in the correct format, and converts to the correct type.
    *  Should throw an error or return null if not valid.
    */
-  public static async create<CreateConfigFileContents>(
+  public static create<CreateConfigFileContents>(
     configPath: string,
     validator: FileContentsValidator<CreateConfigFileContents>
-  ): Promise<FileConfig<CreateConfigFileContents>> {
+  ): FileConfig<CreateConfigFileContents> {
     // Start with empty object, as it can be upgraded to a full config.
     let rawFileContents: any = {};
 
-    if (await Deps.pathExists(configPath)) {
-      rawFileContents = JSON.parse(await Deps.readFile(configPath, 'utf8'));
+    if (Deps.pathExists(configPath)) {
+      rawFileContents = JSON.parse(Deps.readFile(configPath, 'utf8'));
     }
 
     let fileContents = null;
@@ -97,7 +97,7 @@ export class FileConfig<FileContents> {
     await this.persistToDisk();
   }
 
-  public async persistToDisk(): Promise<void> {
+  public async persistToDisk() {
     await Deps.writeFile(this._filePath, JSON.stringify(this._rawConfig, null, 2));
   }
 }

app/server/lib/configCore.ts

@@ -15,8 +15,8 @@ export interface IGristCoreConfig {
   edition: IWritableConfigValue<Edition>;
 }
 
-export async function loadGristCoreConfigFile(configPath?: string): Promise<IGristCoreConfig> {
-  const fileConfig = configPath ? await FileConfig.create(configPath, convertToCoreFileContents) : undefined;
+export function loadGristCoreConfigFile(configPath?: string): IGristCoreConfig {
+  const fileConfig = configPath ? FileConfig.create(configPath, convertToCoreFileContents) : undefined;
   return loadGristCoreConfig(fileConfig);
 }
 

app/server/mergedServerMain.ts

@@ -71,7 +71,7 @@ export async function main(port: number, serverTypes: ServerType[],
   const includeStatic = serverTypes.includes("static");
   const includeApp = serverTypes.includes("app");
 
-  options.settings ??= await getGlobalConfig();
+  options.settings ??= getGlobalConfig();
 
   const server = new FlexServer(port, `server(${serverTypes.join(",")})`, options);
 

stubs/app/server/lib/globalConfig.ts

@@ -9,10 +9,10 @@ let cachedGlobalConfig: IGristCoreConfig | undefined = undefined;
 /**
  * Retrieves the cached grist config, or loads it from the default global path.
  */
-export async function getGlobalConfig(): Promise<IGristCoreConfig> {
+export function getGlobalConfig(): IGristCoreConfig {
   if (!cachedGlobalConfig) {
     log.info(`Loading config file from ${globalConfigPath}`);
-    cachedGlobalConfig = await loadGristCoreConfigFile(globalConfigPath);
+    cachedGlobalConfig = loadGristCoreConfigFile(globalConfigPath);
   }
 
   return cachedGlobalConfig;

test/server/lib/config.ts

@@ -18,7 +18,7 @@ describe('FileConfig', () => {
   const useFakeConfigFile = (contents: string) => {
     const fakeFile = { contents };
     sinon.replace(Deps, 'pathExists', sinon.fake.resolves(true));
-    sinon.replace(Deps, 'readFile', sinon.fake((path, encoding: string) => Promise.resolve(fakeFile.contents)) as any);
+    sinon.replace(Deps, 'readFile', sinon.fake((path, encoding: string) => fakeFile.contents) as any);
     sinon.replace(Deps, 'writeFile', sinon.fake((path, newContents) => {
       fakeFile.contents = newContents;
       return Promise.resolve();
@@ -31,17 +31,17 @@ describe('FileConfig', () => {
     sinon.restore();
   });
 
-  it('throws an error from create if the validator does not return a value', async () => {
+  it('throws an error from create if the validator does not return a value', () => {
     useFakeConfigFile(testFileContentsJSON);
     const validator = () => null;
-    await assert.isRejected(FileConfig.create<TestFileContents>("anypath.json", validator));
+    assert.throws(() => FileConfig.create<TestFileContents>("anypath.json", validator));
   });
 
   it('persists changes when values are assigned', async () => {
     const fakeFile = useFakeConfigFile(testFileContentsJSON);
     // Don't validate - this is guaranteed to be valid above.
     const validator = (input: any) => input as TestFileContents;
-    const fileConfig = await FileConfig.create("anypath.json", validator);
+    const fileConfig = FileConfig.create("anypath.json", validator);
     await fileConfig.set("myNum", 999);
 
     assert.equal(fileConfig.get("myNum"), 999);
@@ -58,7 +58,7 @@ describe('FileConfig', () => {
     const fakeFile = useFakeConfigFile(JSON.stringify(configWithExtraProperties));
     // It's entirely possible the validator can damage the extra properties, but that's not in scope for this test.
     const validator = (input: any) => input as TestFileContents;
-    const fileConfig = await FileConfig.create("anypath.json", validator);
+    const fileConfig = FileConfig.create("anypath.json", validator);
     // Triggering a write to the file
     await fileConfig.set("myNum", 999);
     await fileConfig.set("myStr", "Something");
@@ -94,7 +94,7 @@ describe('createConfigValue', () => {
     assert.equal(accessors.get(), 2);
   });
 
-  it('initialises with the persistent value if available', async () => {
+  it('initialises with the persistent value if available', () => {
     const accessors = makeInMemoryAccessors(22);
     const configValue = createConfigValue(1, accessors);
     assert.equal(configValue.get(), 22);

test/server/lib/configCore.ts

@@ -15,12 +15,12 @@ describe('loadGristCoreConfig', () => {
   });
 
   it('will function correctly when no config file is present', async () => {
-    sinon.replace(Deps, 'pathExists', sinon.fake.resolves(false));
-    sinon.replace(Deps, 'readFile', sinon.fake.resolves(""));
+    sinon.replace(Deps, 'pathExists', sinon.fake.returns(false));
+    sinon.replace(Deps, 'readFile', sinon.fake.returns("" as any));
     const writeFileFake = sinon.fake.resolves(undefined);
     sinon.replace(Deps, 'writeFile', writeFileFake);
 
-    const config = await loadGristCoreConfigFile("doesntmatter.json");
+    const config = loadGristCoreConfigFile("doesntmatter.json");
     assert.exists(config.edition.get());
 
     await config.edition.set("enterprise");

test/server/lib/configCoreFileFormats.ts

@@ -2,7 +2,7 @@ import { assert } from 'chai';
 import { convertToCoreFileContents, IGristCoreConfigFileLatest } from "app/server/lib/configCoreFileFormats";
 
 describe('convertToCoreFileContents', () => {
-  it('fails with a malformed config', async () => {
+  it('fails with a malformed config', () => {
     const badConfig = {
       version: "This is a random version number that will never exist",
     };