Share extended config watchers across projects in server

New shared watcher map in ProjectService that stores callbacks per
project to be invoked when the file watcher is triggered. The
FileWatcher is created with the watch options of the first Project to
watch the extended config.

Author: molisani

src/compiler/watchPublic.ts

@@ -792,7 +792,7 @@ namespace ts {
         }
 
         function watchExtendedConfigFiles() {
-            const configFile = builderProgram.getCompilerOptions().configFile;
+            const { configFile } = builderProgram.getCompilerOptions();
             if (configFile) {
                 updateExtendedConfigFilesWatch(
                     configFile,

src/compiler/watchUtilities.ts

@@ -282,6 +282,73 @@ namespace ts {
         );
     }
 
+    export interface SharedExtendedConfigFileWatcher<P> {
+        watcher: FileWatcher;
+        callbacks: ESMap<P, FileWatcherCallback>;
+    }
+
+    export function updateSharedExtendedConfigFilesWatch<P>(
+        project: P,
+        projectCallback: FileWatcherCallback,
+        configFile: TsConfigSourceFile,
+        sharedExtendedConfigFilesMap: ESMap<string, SharedExtendedConfigFileWatcher<P>>,
+        watchFactory: WatchFactory<WatchType, any>,
+        watchOptions: WatchOptions | undefined
+    ) {
+        const extendedSourceFiles = configFile.extendedSourceFiles || emptyArray;
+        const newSharedExtendedConfigFilesMap = arrayToMap(extendedSourceFiles, identity, returnTrue);
+
+        sharedExtendedConfigFilesMap.forEach((existingWatcher, key) => {
+            if (newSharedExtendedConfigFilesMap.has(key)) {
+                existingWatcher.callbacks.set(project, projectCallback);
+            }
+            else {
+                existingWatcher.callbacks.delete(project);
+                if (existingWatcher.callbacks.size === 0) {
+                    sharedExtendedConfigFilesMap.delete(key);
+                    closeFileWatcherOf(existingWatcher);
+                }
+            }
+        });
+
+        newSharedExtendedConfigFilesMap.forEach((_true, extendedConfigPath) => {
+            if (!sharedExtendedConfigFilesMap.has(extendedConfigPath)) {
+                const newWatcher = createSharedExtendedConfigFileWatcher(extendedConfigPath);
+                sharedExtendedConfigFilesMap.set(extendedConfigPath, newWatcher);
+            }
+        });
+
+        function createSharedExtendedConfigFileWatcher(extendedConfigPath: string) {
+            const callbacks = new Map<P, FileWatcherCallback>();
+            callbacks.set(project, projectCallback);
+            const watcher = watchFactory.watchFile(
+                extendedConfigPath,
+                invokeProjectCallbacks,
+                PollingInterval.High,
+                watchOptions,
+                WatchType.ExtendedConfigFile
+            );
+            return { watcher, callbacks };
+
+            function invokeProjectCallbacks(fileName: string, eventKind: FileWatcherEventKind) {
+                return callbacks.forEach((callback) => callback(fileName, eventKind));
+            }
+        }
+    }
+
+    export function removeProjectFromSharedExtendedConfigFilesWatch<P>(
+        project: P,
+        sharedExtendedConfigFilesMap: ESMap<string, SharedExtendedConfigFileWatcher<P>>
+    ) {
+        sharedExtendedConfigFilesMap.forEach((existingWatcher, key) => {
+            existingWatcher.callbacks.delete(project);
+            if (existingWatcher.callbacks.size === 0) {
+                sharedExtendedConfigFilesMap.delete(key);
+                closeFileWatcherOf(existingWatcher);
+            }
+        });
+    }
+
     /**
      * Updates the existing missing file watches with the new set of missing files after new program is created
      */

src/server/editorServices.ts

@@ -756,6 +756,9 @@ namespace ts.server {
         /*@internal*/
         readonly watchFactory: WatchFactory<WatchType, Project>;
 
+        /*@internal*/
+        private sharedExtendedConfigFilesMap = new Map<string, SharedExtendedConfigFileWatcher<Project>>();
+
         /*@internal*/
         readonly packageJsonCache: PackageJsonCache;
         /*@internal*/
@@ -1384,6 +1387,7 @@ namespace ts.server {
             project.print(/*writeProjectFileNames*/ true);
 
             project.close();
+            removeProjectFromSharedExtendedConfigFilesWatch(project, this.sharedExtendedConfigFilesMap);
             if (Debug.shouldAssert(AssertionLevel.Normal)) {
                 this.filenameToScriptInfo.forEach(info => Debug.assert(
                     !info.isAttached(project),
@@ -2156,15 +2160,24 @@ namespace ts.server {
             const lastFileExceededProgramSize = this.getFilenameForExceededTotalSizeLimitForNonTsFiles(project.canonicalConfigFilePath, compilerOptions, parsedCommandLine.fileNames, fileNamePropertyReader);
             if (lastFileExceededProgramSize) {
                 project.disableLanguageService(lastFileExceededProgramSize);
-                project.stopWatchingExtendedConfigFiles();
                 project.stopWatchingWildCards();
+                removeProjectFromSharedExtendedConfigFilesWatch(project, this.sharedExtendedConfigFilesMap);
             }
             else {
                 project.setCompilerOptions(compilerOptions);
                 project.setWatchOptions(parsedCommandLine.watchOptions);
                 project.enableLanguageService();
-                project.watchExtendedConfigFiles();
                 project.watchWildcards(new Map(getEntries(parsedCommandLine.wildcardDirectories!))); // TODO: GH#18217
+                if (compilerOptions.configFile) {
+                    updateSharedExtendedConfigFilesWatch(
+                        project,
+                        (fileName) => this.onExtendedConfigChangedForConfiguredProject(project, fileName),
+                        compilerOptions.configFile,
+                        this.sharedExtendedConfigFilesMap,
+                        this.watchFactory,
+                        this.hostConfiguration.watchOptions,
+                    );
+                }
             }
             project.enablePluginsWithOptions(compilerOptions, this.currentPluginConfigOverrides);
             const filesToAdd = parsedCommandLine.fileNames.concat(project.getExternalFiles());

src/server/project.ts

@@ -2046,8 +2046,6 @@ namespace ts.server {
     export class ConfiguredProject extends Project {
         /* @internal */
         configFileWatcher: FileWatcher | undefined;
-        /* @internal */
-        private extendedConfigFileWatchers: ESMap<string, FileWatcher> | undefined;
         private directoriesWatchedForWildcards: ESMap<string, WildcardDirectoryWatcher> | undefined;
         readonly canonicalConfigFilePath: NormalizedPath;
 
@@ -2261,38 +2259,6 @@ namespace ts.server {
             this.projectErrors = projectErrors;
         }
 
-        /* @internal */
-        createExtendedConfigFileWatcher(extendedConfigFile: string): FileWatcher {
-            return this.projectService.watchFactory.watchFile(
-                extendedConfigFile,
-                (fileName) => this.projectService.onExtendedConfigChangedForConfiguredProject(this, fileName),
-                PollingInterval.High,
-                this.projectService.getWatchOptions(this),
-                WatchType.ExtendedConfigFile,
-                this
-            );
-        }
-
-        /* @internal */
-        watchExtendedConfigFiles() {
-            const configFile = this.getCompilerOptions().configFile;
-            if (configFile) {
-                updateExtendedConfigFilesWatch(
-                    configFile,
-                    this.extendedConfigFileWatchers || (this.extendedConfigFileWatchers = new Map()),
-                    (extendedConfigFile) => this.createExtendedConfigFileWatcher(extendedConfigFile),
-                );
-            }
-        }
-
-        /* @internal */
-        stopWatchingExtendedConfigFiles() {
-            if (this.extendedConfigFileWatchers) {
-                clearMap(this.extendedConfigFileWatchers, closeFileWatcher);
-                this.extendedConfigFileWatchers = undefined;
-            }
-        }
-
         /*@internal*/
         watchWildcards(wildcardDirectories: ESMap<string, WatchDirectoryFlags>) {
             updateWatchingWildcardDirectories(
@@ -2317,7 +2283,6 @@ namespace ts.server {
                 this.configFileWatcher = undefined;
             }
 
-            this.stopWatchingExtendedConfigFiles();
             this.stopWatchingWildCards();
             this.configFileSpecs = undefined;
             this.openFileWatchTriggered.clear();