6 files changed, 124 insertions, 143 deletions

diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index c3a3583b5..d3ef27e43 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -1,6 +1,7 @@
 import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
 import { Server } from './server';
+import { Config } from './config';
 
 export class Ctx {
     private extCtx: vscode.ExtensionContext;
@@ -13,6 +14,10 @@ export class Ctx {
         return Server.client;
     }
 
+    get config(): Config {
+        return Server.config;
+    }
+
     get activeRustEditor(): vscode.TextEditor | undefined {
         const editor = vscode.window.activeTextEditor;
         return editor && editor.document.languageId === 'rust'
@@ -56,6 +61,24 @@ export class Ctx {
     pushCleanup(d: { dispose(): any }) {
         this.extCtx.subscriptions.push(d);
     }
+
+    async sendRequestWithRetry<R>(method: string, param: any, token: vscode.CancellationToken): Promise<R> {
+        await this.client.onReady();
+        for (const delay of [2, 4, 6, 8, 10, null]) {
+            try {
+                return await this.client.sendRequest(method, param, token);
+            } catch (e) {
+                if (e.code === lc.ErrorCodes.ContentModified && delay !== null) {
+                    await sleep(10 * (1 << delay))
+                    continue;
+                }
+                throw e;
+            }
+        }
+        throw 'unreachable'
+    }
 }
 
 export type Cmd = (...args: any[]) => any;
+
+const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms))
diff --git a/editors/code/src/events/change_active_text_editor.ts b/editors/code/src/events/change_active_text_editor.ts
deleted file mode 100644
index 4384ee567..000000000
--- a/editors/code/src/events/change_active_text_editor.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-import { TextEditor } from 'vscode';
-import { TextDocumentIdentifier } from 'vscode-languageclient';
-import { Decoration } from '../highlighting';
-import { Server } from '../server';
-
-export function makeHandler() {
-    return async function handle(editor: TextEditor | undefined) {
-        if (!editor || editor.document.languageId !== 'rust') {
-            return;
-        }
-
-        if (!Server.config.highlightingOn) {
-            return;
-        }
-
-        const params: TextDocumentIdentifier = {
-            uri: editor.document.uri.toString(),
-        };
-        const decorations = await Server.client.sendRequest<Decoration[]>(
-            'rust-analyzer/decorationsRequest',
-            params,
-        );
-        Server.highlighter.setHighlights(editor, decorations);
-    };
-}
diff --git a/editors/code/src/events/index.ts b/editors/code/src/events/index.ts
deleted file mode 100644
index be135474d..000000000
--- a/editors/code/src/events/index.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import * as changeActiveTextEditor from './change_active_text_editor';
-
-export { changeActiveTextEditor };
diff --git a/editors/code/src/highlighting.ts b/editors/code/src/highlighting.ts
index 4e224a54c..333319b85 100644
--- a/editors/code/src/highlighting.ts
+++ b/editors/code/src/highlighting.ts
@@ -1,10 +1,31 @@
-import seedrandom = require('seedrandom');
 import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
+import * as seedrandom_ from 'seedrandom';
+const seedrandom = seedrandom_; // https://github.com/jvandemo/generator-angular2-library/issues/221#issuecomment-355945207
+
 import * as scopes from './scopes';
 import * as scopesMapper from './scopes_mapper';
 
 import { Server } from './server';
+import { Ctx } from './ctx';
+
+export function activateHighlighting(ctx: Ctx) {
+    vscode.window.onDidChangeActiveTextEditor(
+        async (editor: vscode.TextEditor | undefined) => {
+            if (!editor || editor.document.languageId !== 'rust') return;
+            if (!ctx.config.highlightingOn) return;
+
+            const params: lc.TextDocumentIdentifier = {
+                uri: editor.document.uri.toString(),
+            };
+            const decorations = await ctx.client.sendRequest<Decoration[]>(
+                'rust-analyzer/decorationsRequest',
+                params,
+            );
+            Server.highlighter.setHighlights(editor, decorations);
+        },
+    );
+}
 
 export interface Decoration {
     range: lc.Range;
diff --git a/editors/code/src/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index 4581e2278..d41297407 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -1,41 +1,27 @@
 import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
-import { Server } from './server';
+
 import { Ctx } from './ctx';
 
 export function activateInlayHints(ctx: Ctx) {
-    const hintsUpdater = new HintsUpdater();
-    hintsUpdater.refreshHintsForVisibleEditors().then(() => {
-        // vscode may ignore top level hintsUpdater.refreshHintsForVisibleEditors()
-        // so update the hints once when the focus changes to guarantee their presence
-        let editorChangeDisposable: vscode.Disposable | null = null;
-        editorChangeDisposable = vscode.window.onDidChangeActiveTextEditor(
-            _ => {
-                if (editorChangeDisposable !== null) {
-                    editorChangeDisposable.dispose();
-                }
-                return hintsUpdater.refreshHintsForVisibleEditors();
-            },
-        );
+    const hintsUpdater = new HintsUpdater(ctx);
+    vscode.window.onDidChangeVisibleTextEditors(async _ => {
+        await hintsUpdater.refresh();
+    }, ctx.subscriptions);
 
-        ctx.pushCleanup(
-            vscode.window.onDidChangeVisibleTextEditors(_ =>
-                hintsUpdater.refreshHintsForVisibleEditors(),
-            ),
-        );
-        ctx.pushCleanup(
-            vscode.workspace.onDidChangeTextDocument(e =>
-                hintsUpdater.refreshHintsForVisibleEditors(e),
-            ),
-        );
-        ctx.pushCleanup(
-            vscode.workspace.onDidChangeConfiguration(_ =>
-                hintsUpdater.toggleHintsDisplay(
-                    Server.config.displayInlayHints,
-                ),
-            ),
-        );
-    });
+    vscode.workspace.onDidChangeTextDocument(async e => {
+        if (e.contentChanges.length === 0) return;
+        if (e.document.languageId !== 'rust') return;
+        await hintsUpdater.refresh();
+    }, ctx.subscriptions);
+
+    vscode.workspace.onDidChangeConfiguration(_ => {
+        hintsUpdater.setEnabled(ctx.config.displayInlayHints);
+    }, ctx.subscriptions);
+
+    // XXX: don't await here;
+    // Who knows what happens if an exception is thrown here...
+    hintsUpdater.refresh();
 }
 
 interface InlayHintsParams {
@@ -55,95 +41,79 @@ const typeHintDecorationType = vscode.window.createTextEditorDecorationType({
 });
 
 class HintsUpdater {
-    private displayHints = true;
+    private pending: Map<string, vscode.CancellationTokenSource> = new Map();
+    private ctx: Ctx;
+    private enabled = true;
 
-    public async toggleHintsDisplay(displayHints: boolean): Promise<void> {
-        if (this.displayHints !== displayHints) {
-            this.displayHints = displayHints;
-            return this.refreshVisibleEditorsHints(
-                displayHints ? undefined : [],
-            );
-        }
+    constructor(ctx: Ctx) {
+        this.ctx = ctx;
     }
 
-    public async refreshHintsForVisibleEditors(
-        cause?: vscode.TextDocumentChangeEvent,
-    ): Promise<void> {
-        if (!this.displayHints) return;
-
-        if (
-            cause !== undefined &&
-            (cause.contentChanges.length === 0 ||
-                !this.isRustDocument(cause.document))
-        ) {
-            return;
+    async setEnabled(enabled: boolean) {
+        if (this.enabled == enabled) return;
+        this.enabled = enabled;
+
+        if (this.enabled) {
+            await this.refresh();
+        } else {
+            this.allEditors.forEach(it => this.setDecorations(it, []));
         }
-        return this.refreshVisibleEditorsHints();
     }
 
-    private async refreshVisibleEditorsHints(
-        newDecorations?: vscode.DecorationOptions[],
-    ) {
-        const promises: Array<Promise<void>> = [];
-
-        for (const rustEditor of vscode.window.visibleTextEditors.filter(
-            editor => this.isRustDocument(editor.document),
-        )) {
-            if (newDecorations !== undefined) {
-                promises.push(
-                    Promise.resolve(
-                        rustEditor.setDecorations(
-                            typeHintDecorationType,
-                            newDecorations,
-                        ),
-                    ),
-                );
-            } else {
-                promises.push(this.updateDecorationsFromServer(rustEditor));
-            }
-        }
+    async refresh() {
+        if (!this.enabled) return;
+        const promises = this.allEditors.map(it => this.refreshEditor(it));
+        await Promise.all(promises);
+    }
 
-        for (const promise of promises) {
-            await promise;
-        }
+    private async refreshEditor(editor: vscode.TextEditor): Promise<void> {
+        const newHints = await this.queryHints(editor.document.uri.toString());
+        if (newHints == null) return;
+        const newDecorations = newHints.map(hint => ({
+            range: hint.range,
+            renderOptions: {
+                after: {
+                    contentText: `: ${hint.label}`,
+                },
+            },
+        }));
+        this.setDecorations(editor, newDecorations);
     }
 
-    private isRustDocument(document: vscode.TextDocument): boolean {
-        return document && document.languageId === 'rust';
+    private get allEditors(): vscode.TextEditor[] {
+        return vscode.window.visibleTextEditors.filter(
+            editor => editor.document.languageId === 'rust',
+        );
     }
 
-    private async updateDecorationsFromServer(
+    private setDecorations(
         editor: vscode.TextEditor,
-    ): Promise<void> {
-        const newHints = await this.queryHints(editor.document.uri.toString());
-        if (newHints !== null) {
-            const newDecorations = newHints.map(hint => ({
-                range: hint.range,
-                renderOptions: {
-                    after: {
-                        contentText: `: ${hint.label}`,
-                    },
-                },
-            }));
-            return editor.setDecorations(
-                typeHintDecorationType,
-                newDecorations,
-            );
-        }
+        decorations: vscode.DecorationOptions[],
+    ) {
+        editor.setDecorations(
+            typeHintDecorationType,
+            this.enabled ? decorations : [],
+        );
     }
 
     private async queryHints(documentUri: string): Promise<InlayHint[] | null> {
         const request: InlayHintsParams = {
             textDocument: { uri: documentUri },
         };
-        const client = Server.client;
-        return client
-            .onReady()
-            .then(() =>
-                client.sendRequest<InlayHint[] | null>(
-                    'rust-analyzer/inlayHints',
-                    request,
-                ),
+        let tokenSource = new vscode.CancellationTokenSource();
+        let prev = this.pending.get(documentUri);
+        if (prev) prev.cancel()
+        this.pending.set(documentUri, tokenSource);
+        try {
+            return await this.ctx.sendRequestWithRetry<InlayHint[] | null>(
+                'rust-analyzer/inlayHints',
+                request,
+                tokenSource.token,
             );
+        } finally {
+            if (!tokenSource.token.isCancellationRequested) {
+                this.pending.delete(documentUri)
+            }
+        }
     }
 }
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 7e63a9cac..345ae0685 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -4,10 +4,10 @@ import * as lc from 'vscode-languageclient';
 import * as commands from './commands';
 import { activateInlayHints } from './inlay_hints';
 import { StatusDisplay } from './status_display';
-import * as events from './events';
 import * as notifications from './notifications';
 import { Server } from './server';
 import { Ctx } from './ctx';
+import { activateHighlighting } from './highlighting';
 
 let ctx!: Ctx;
 
@@ -28,15 +28,15 @@ export async function activate(context: vscode.ExtensionContext) {
     ctx.registerCommand('runSingle', commands.runSingle);
     ctx.registerCommand('showReferences', commands.showReferences);
 
-    if (Server.config.enableEnhancedTyping) {
+    if (ctx.config.enableEnhancedTyping) {
         ctx.overrideCommand('type', commands.onEnter);
     }
 
-    const watchStatus = new StatusDisplay(
-        Server.config.cargoWatchOptions.command,
-    );
+    const watchStatus = new StatusDisplay(ctx.config.cargoWatchOptions.command);
     ctx.pushCleanup(watchStatus);
 
+    activateHighlighting(ctx);
+
     // Notifications are events triggered by the language server
     const allNotifications: [string, lc.GenericNotificationHandler][] = [
         [
@@ -49,11 +49,6 @@ export async function activate(context: vscode.ExtensionContext) {
         ],
     ];
 
-    // The events below are plain old javascript events, triggered and handled by vscode
-    vscode.window.onDidChangeActiveTextEditor(
-        events.changeActiveTextEditor.makeHandler(),
-    );
-
     const startServer = () => Server.start(allNotifications);
     const reloadCommand = () => reloadServer(startServer);
 
@@ -66,7 +61,7 @@ export async function activate(context: vscode.ExtensionContext) {
         vscode.window.showErrorMessage(e.message);
     }
 
-    if (Server.config.displayInlayHints) {
+    if (ctx.config.displayInlayHints) {
         activateInlayHints(ctx);
     }
 }