1 files changed, 54 insertions, 10 deletions

diff --git a/editors/code/src/util.ts b/editors/code/src/util.ts
index 352ef9162..970fedb37 100644
--- a/editors/code/src/util.ts
+++ b/editors/code/src/util.ts
@@ -2,6 +2,7 @@ import * as lc from "vscode-languageclient";
 import * as vscode from "vscode";
 import { strict as nativeAssert } from "assert";
 import { spawnSync } from "child_process";
+import { inspect } from "util";
 
 export function assert(condition: boolean, explanation: string): asserts condition {
     try {
@@ -14,22 +15,46 @@ export function assert(condition: boolean, explanation: string): asserts conditi
 
 export const log = new class {
     private enabled = true;
+    private readonly output = vscode.window.createOutputChannel("Rust Analyzer Client");
 
     setEnabled(yes: boolean): void {
         log.enabled = yes;
     }
 
-    debug(message?: any, ...optionalParams: any[]): void {
+    // Hint: the type [T, ...T[]] means a non-empty array
+    debug(...msg: [unknown, ...unknown[]]): void {
         if (!log.enabled) return;
-        // eslint-disable-next-line no-console
-        console.log(message, ...optionalParams);
+        log.write("DEBUG", ...msg);
+        log.output.toString();
     }
 
-    error(message?: any, ...optionalParams: any[]): void {
-        if (!log.enabled) return;
+    info(...msg: [unknown, ...unknown[]]): void {
+        log.write("INFO", ...msg);
+    }
+
+    warn(...msg: [unknown, ...unknown[]]): void {
+        debugger;
+        log.write("WARN", ...msg);
+    }
+
+    error(...msg: [unknown, ...unknown[]]): void {
         debugger;
-        // eslint-disable-next-line no-console
-        console.error(message, ...optionalParams);
+        log.write("ERROR", ...msg);
+        log.output.show(true);
+    }
+
+    private write(label: string, ...messageParts: unknown[]): void {
+        const message = messageParts.map(log.stringify).join(" ");
+        const dateTime = new Date().toLocaleString();
+        log.output.appendLine(`${label} [${dateTime}]: ${message}`);
+    }
+
+    private stringify(val: unknown): string {
+        if (typeof val === "string") return val;
+        return inspect(val, {
+            colors: false,
+            depth: 6, // heuristic
+        });
     }
 };
 
@@ -47,7 +72,7 @@ export async function sendRequestWithRetry<TParam, TRet>(
             );
         } catch (error) {
             if (delay === null) {
-                log.error("LSP request timed out", { method: reqType.method, param, error });
+                log.warn("LSP request timed out", { method: reqType.method, param, error });
                 throw error;
             }
 
@@ -56,7 +81,7 @@ export async function sendRequestWithRetry<TParam, TRet>(
             }
 
             if (error.code !== lc.ErrorCodes.ContentModified) {
-                log.error("LSP request failed", { method: reqType.method, param, error });
+                log.warn("LSP request failed", { method: reqType.method, param, error });
                 throw error;
             }
 
@@ -90,7 +115,8 @@ export function isValidExecutable(path: string): boolean {
 
     const res = spawnSync(path, ["--version"], { encoding: 'utf8' });
 
-    log.debug(res, "--version output:", res.output);
+    const printOutput = res.error && (res.error as any).code !== 'ENOENT' ? log.warn : log.debug;
+    printOutput(path, "--version:", res);
 
     return res.status === 0;
 }
@@ -99,3 +125,21 @@ export function isValidExecutable(path: string): boolean {
 export function setContextValue(key: string, value: any): Thenable<void> {
     return vscode.commands.executeCommand('setContext', key, value);
 }
+
+/**
+ * Returns a higher-order function that caches the results of invoking the
+ * underlying function.
+ */
+export function memoize<Ret, TThis, Param extends string>(func: (this: TThis, arg: Param) => Ret) {
+    const cache = new Map<string, Ret>();
+
+    return function(this: TThis, arg: Param) {
+        const cached = cache.get(arg);
+        if (cached) return cached;
+
+        const result = func.call(this, arg);
+        cache.set(arg, result);
+
+        return result;
+    };
+}