Cache existing flow paths

lib/flowMain.js

@@ -1,50 +1,56 @@
-/* @flow */
-
-/*
- Copyright (c) 2015-present, Facebook, Inc.
- All rights reserved.
- *
- * This source code is licensed under the license found in the LICENSE file in
- the root directory of this source tree.
- */
-
-// Necessary to get the regenerator runtime, which transpiled async functions need
-import * as _ from 'regenerator-runtime/runtime';
-
-import * as vscode from 'vscode';
-
-import {CompletionSupport} from './flowCompletion';
-import {HoverSupport} from './flowHover'
-import {DeclarationSupport} from './flowDeclaration';
-import {setupDiagnostics} from './flowDiagnostics';
-
-import {checkNode, checkFlow, isFlowEnabled} from './utils'
-
-type Context = {
-	subscriptions: Array<vscode.Disposable>
-}
-
-const languages = [
-	{ language: 'javascript', scheme: 'file' },
-	'javascriptreact'
-]
-
-export function activate(context: Context): void {
-	//User can disable flow for some projects that previously used flow, but it's not have actual typing
-	if (!isFlowEnabled()) {
-		return
-	}
-	global.vscode = vscode
-	checkNode()
-	checkFlow()
-	// Language features
-	languages.forEach(lang => {
-		context.subscriptions.push(vscode.languages.registerHoverProvider(lang, new HoverSupport));
-		context.subscriptions.push(vscode.languages.registerDefinitionProvider(lang, new DeclarationSupport()));
-		context.subscriptions.push(vscode.languages.registerCompletionItemProvider(lang, new CompletionSupport(), '.'));
-	})
-	// https://github.com/Microsoft/vscode/issues/7031 Workaround for language scoring for language and in-memory. Check in nearest Insiders build
-	// context.subscriptions.push(vscode.languages.registerCompletionItemProvider({ language: 'javascript' }, new CompletionSupport(), '.'));
-	// Diagnostics
-	setupDiagnostics(context.subscriptions);
-}
+/* @flow */
+
+/*
+ Copyright (c) 2015-present, Facebook, Inc.
+ All rights reserved.
+ *
+ * This source code is licensed under the license found in the LICENSE file in
+ the root directory of this source tree.
+ */
+
+// Necessary to get the regenerator runtime, which transpiled async functions need
+import * as _ from 'regenerator-runtime/runtime';
+
+import * as vscode from 'vscode';
+
+import {CompletionSupport} from './flowCompletion';
+import {HoverSupport} from './flowHover'
+import {DeclarationSupport} from './flowDeclaration';
+import {setupDiagnostics} from './flowDiagnostics';
+
+import {checkNode, checkFlow, isFlowEnabled} from './utils'
+import {clearCaches} from './pkg/flow-base/lib/FlowHelpers'
+
+type Context = {
+	subscriptions: Array<vscode.Disposable>
+}
+
+const languages = [
+	{ language: 'javascript', scheme: 'file' },
+	'javascriptreact'
+]
+
+export function activate(context: Context): void {
+	//User can disable flow for some projects that previously used flow, but it's not have actual typing
+	if (!isFlowEnabled()) {
+		return
+	}
+	global.vscode = vscode
+	checkNode()
+	checkFlow()
+
+	// Language features
+	languages.forEach(lang => {
+		context.subscriptions.push(vscode.languages.registerHoverProvider(lang, new HoverSupport));
+		context.subscriptions.push(vscode.languages.registerDefinitionProvider(lang, new DeclarationSupport()));
+		context.subscriptions.push(vscode.languages.registerCompletionItemProvider(lang, new CompletionSupport(), '.'));
+	})
+	// https://github.com/Microsoft/vscode/issues/7031 Workaround for language scoring for language and in-memory. Check in nearest Insiders build
+	// context.subscriptions.push(vscode.languages.registerCompletionItemProvider({ language: 'javascript' }, new CompletionSupport(), '.'));
+	// Diagnostics
+	setupDiagnostics(context.subscriptions);
+}
+
+vscode.workspace.onDidChangeConfiguration(params => {
+	clearWorkspaceCaches();
+});

lib/pkg/flow-base/lib/FlowHelpers.js

@@ -124,6 +124,12 @@ function isOptional(param: string): boolean {
   return lastChar === '?';
 }
 
+function clearWorkspaceCaches() {
+  flowPathCache.reset();
+  flowConfigDirCache.reset();
+  cachedPathToFlowBin = undefined;
+}
+
 async function isFlowInstalled(): Promise<boolean> {
   const flowPath = await getPathToFlow();
   if (!flowPathCache.has(flowPath)) {
@@ -144,32 +150,38 @@ async function canFindFlow(flowPath: string): Promise<boolean> {
 }
 
 /**
- * @return The path to Flow on the user's machine. First using the the user's config, then looking into
- *   the node_modules for the project.
- *   It is recommended not to cache the result of this function in case the user updates his or her 
- *   preferences in Atom, in which case the return value will be stale.
+ * @return The path to Flow on the user's machine. First using the the user's 
+ *   config, then looking into the node_modules for the project.
+ * 
+ *   It is cached, so it is expected that changing the users settings will 
+ *   trigger a call to `clearWorkspaceCaches`.
  */
+let cachedPathToFlowBin = undefined
 async function getPathToFlow(): Promise<string> {
-  const config = global.vscode.workspace.getConfiguration('flow')
-  const userPath = config.get('pathToFlow')
+  if (cachedPathToFlowBin) return { cachedPathToFlow }
 
-  if (await canFindFlow(userPath)) {
-    return userPath
+  const config = global.vscode.workpace.getConfiguration('flow');
+  const shouldUseNodeModule = config.get('useNPMPackagedFlow');
+
+  if (shouldUseNodeModule && await canFindFlow(nodeModuleFlowLocation())){
+    cachedPathToFlow = nodeModuleFlowLocation(); 
+    return cachedPathToFlow
   }
 
-  const shouldUseNodeModule = config.get('useNPMPackagedFlow')
-  if (shouldUseNodeModule && await canFindFlow(fallbackNodeModuleFlowLocation())){
-    return fallbackNodeModuleFlowLocation()
+  const userPath = config.get('pathToFlow');
+  if (await canFindFlow(userPath)) {
+    cachedPathToFlow = userPath 
+    return cachedPathToFlow
   }
-  return userPath
 }
 
 /**
- * @return The potential path to Flow on the user's machine if they are using NPM/Yarn to manage
+ * @returnThe potential path to Flow on the user's machine if they are using NPM/Yarn to manage
  * their installs of flow.
  */
-function fallbackNodeModuleFlowLocation(): string {
-  return global.vscode.workspace.rootPath + "/node_modules/.bin/flow"
+function nodeModuleFlowLocation(): string {
+  const flowBin = process.platform === 'win32' ? 'flow.cmd' : 'flow'
+  return `${global.vscode.workspace.rootPath}/node_modules/.bin/${flowBin}`
 }
 
 function getStopFlowOnExit(): boolean {
@@ -212,4 +224,5 @@ module.exports = {
   processAutocompleteItem,
   groupParamNames,
   flowCoordsToAtomCoords,
+  clearWorkspaceCaches
 };