Fix issues surrounding initial web server load. (#4509)

- Clean up watcher behaviors.

src/node/routes/vscode.ts

@@ -4,7 +4,7 @@ import { WebsocketRequest } from "../../../typings/pluginapi"
 import { logError } from "../../common/util"
 import { isDevMode } from "../constants"
 import { ensureAuthenticated, authenticated, redirect } from "../http"
-import { loadAMDModule } from "../util"
+import { loadAMDModule, readCompilationStats } from "../util"
 import { Router as WsRouter } from "../wsRouter"
 import { errorHandler } from "./errors"
 
@@ -40,7 +40,6 @@ export class CodeServerRouteWrapper {
       if (error instanceof Error && ["EntryNotFound", "FileNotFound", "HttpError"].includes(error.message)) {
         next()
       }
-
       errorHandler(error, req, res, next)
     }
 
@@ -62,9 +61,21 @@ export class CodeServerRouteWrapper {
    */
   private ensureCodeServerLoaded: express.Handler = async (req, _res, next) => {
     if (this._codeServerMain) {
+      // Already loaded...
       return next()
     }
 
+    if (isDevMode) {
+      // Is the development mode file watcher still busy?
+      const compileStats = await readCompilationStats()
+
+      if (!compileStats || !compileStats.lastCompiledAt) {
+        return next(new Error("VS Code may still be compiling..."))
+      }
+    }
+
+    // Create the server...
+
     const { args } = req
 
     /**
@@ -84,10 +95,7 @@ export class CodeServerRouteWrapper {
       })
     } catch (createServerError) {
       logError(logger, "CodeServerRouteWrapper", createServerError)
-
-      const loggedError = isDevMode ? new Error("VS Code may still be compiling...") : createServerError
-
-      return next(loggedError)
+      return next(createServerError)
     }
 
     return next()

src/node/util.ts

@@ -3,14 +3,15 @@ import * as argon2 from "argon2"
 import * as cp from "child_process"
 import * as crypto from "crypto"
 import envPaths from "env-paths"
-import { promises as fs } from "fs"
+import { promises as fs, Stats } from "fs"
 import * as net from "net"
 import * as os from "os"
 import * as path from "path"
 import safeCompare from "safe-compare"
 import * as util from "util"
 import xdgBasedir from "xdg-basedir"
-import { vsRootPath } from "./constants"
+import { logError } from "../common/util"
+import { isDevMode, rootPath, vsRootPath } from "./constants"
 
 export interface Paths {
   data: string
@@ -25,10 +26,11 @@ const pattern = [
 ].join("|")
 const re = new RegExp(pattern, "g")
 
+export type OnLineCallback = (strippedLine: string, originalLine: string) => void
 /**
  * Split stdout on newlines and strip ANSI codes.
  */
-export const onLine = (proc: cp.ChildProcess, callback: (strippedLine: string, originalLine: string) => void): void => {
+export const onLine = (proc: cp.ChildProcess, callback: OnLineCallback): void => {
   let buffer = ""
   if (!proc.stdout) {
     throw new Error("no stdout")
@@ -521,3 +523,41 @@ export const loadAMDModule = async <T>(amdPath: string, exportName: string): Pro
 
   return module[exportName] as T
 }
+
+export const enum VSCodeCompileStatus {
+  Loading = "Loading",
+  Compiling = "Compiling",
+  Compiled = "Compiled",
+}
+
+export interface CompilationStats {
+  status: VSCodeCompileStatus
+  lastCompiledAt: Date
+}
+
+export const readCompilationStats = async (): Promise<null | CompilationStats> => {
+  if (!isDevMode) {
+    throw new Error("Compilation stats are only present in development")
+  }
+
+  const filePath = path.join(rootPath, "out/watcher.json")
+  let stat: Stats
+  try {
+    stat = await fs.stat(filePath)
+  } catch (error) {
+    return null
+  }
+
+  if (!stat.isFile()) {
+    return null
+  }
+
+  try {
+    const file = await fs.readFile(filePath)
+    return JSON.parse(file.toString("utf-8"))
+  } catch (error) {
+    logError(logger, "VS Code", error)
+  }
+
+  return null
+}