From cdd7118cbf23e21c376092b3b2734407004b8dbf Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Mon, 30 Dec 2019 22:53:21 +0100
Subject: Don't request inline hints repeatedly

---
 editors/code/src/ctx.ts         | 13 ++++++++-----
 editors/code/src/inlay_hints.ts | 23 ++++++++++++++++++-----
 2 files changed, 26 insertions(+), 10 deletions(-)

(limited to 'editors/code')

diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index 75b3542f4..d3ef27e43 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -62,20 +62,23 @@ export class Ctx {
         this.extCtx.subscriptions.push(d);
     }
 
-    async sendRequestWithRetry<R>(method: string, param: any): Promise<R> {
+    async sendRequestWithRetry<R>(method: string, param: any, token: vscode.CancellationToken): Promise<R> {
         await this.client.onReady();
-        const nRetries = 3;
-        for (let triesLeft = nRetries; ; triesLeft--) {
+        for (const delay of [2, 4, 6, 8, 10, null]) {
             try {
-                return await this.client.sendRequest(method, param);
+                return await this.client.sendRequest(method, param, token);
             } catch (e) {
-                if (e.code === lc.ErrorCodes.ContentModified && triesLeft > 0) {
+                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/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index 16faea22e..d41297407 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -41,6 +41,7 @@ const typeHintDecorationType = vscode.window.createTextEditorDecorationType({
 });
 
 class HintsUpdater {
+    private pending: Map<string, vscode.CancellationTokenSource> = new Map();
     private ctx: Ctx;
     private enabled = true;
 
@@ -67,7 +68,8 @@ class HintsUpdater {
 
     private async refreshEditor(editor: vscode.TextEditor): Promise<void> {
         const newHints = await this.queryHints(editor.document.uri.toString());
-        const newDecorations = (newHints ? newHints : []).map(hint => ({
+        if (newHints == null) return;
+        const newDecorations = newHints.map(hint => ({
             range: hint.range,
             renderOptions: {
                 after: {
@@ -98,9 +100,20 @@ class HintsUpdater {
         const request: InlayHintsParams = {
             textDocument: { uri: documentUri },
         };
-        return this.ctx.sendRequestWithRetry<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)
+            }
+        }
     }
 }
-- 
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