Wrapping LSHost's cancellationtoken with a throttle

Author: jramsay

src/harness/unittests/tsserverProjectSystem.ts

@@ -176,11 +176,11 @@ namespace ts.projectSystem {
         }
     };
 
-    export function createSession(host: server.ServerHost, typingsInstaller?: server.ITypingsInstaller, projectServiceEventHandler?: server.ProjectServiceEventHandler, cancellationToken?: server.ServerCancellationToken) {
+    export function createSession(host: server.ServerHost, typingsInstaller?: server.ITypingsInstaller, projectServiceEventHandler?: server.ProjectServiceEventHandler, cancellationToken?: server.ServerCancellationToken, throttleWaitMilliseconds?: number) {
         if (typingsInstaller === undefined) {
             typingsInstaller = new TestTypingsInstaller("/a/data/", /*throttleLimit*/5, host);
         }
-        return new TestSession(host, cancellationToken || server.nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ projectServiceEventHandler !== undefined, projectServiceEventHandler);
+        return new TestSession(host, cancellationToken || server.nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ projectServiceEventHandler !== undefined, projectServiceEventHandler, throttleWaitMilliseconds);
     }
 
     export interface CreateProjectServiceParameters {
@@ -3320,6 +3320,7 @@ namespace ts.projectSystem {
                 },
                 resetRequest: noop
             }
+
             const session = createSession(host, /*typingsInstaller*/ undefined, /*projectServiceEventHandler*/ undefined, cancellationToken);
 
             expectedRequestId = session.getNextSeq();
@@ -3492,7 +3493,7 @@ namespace ts.projectSystem {
             };
             const cancellationToken = new TestServerCancellationToken(/*cancelAfterRequest*/ 3);
             const host = createServerHost([f1, config]);
-            const session = createSession(host, /*typingsInstaller*/ undefined, () => { }, cancellationToken);
+            const session = createSession(host, /*typingsInstaller*/ undefined, () => { }, cancellationToken, /*throttleWaitMilliseconds*/ 0);
             {
                 session.executeCommandSeq(<protocol.OpenRequest>{
                     command: "open",

src/server/editorServices.ts

@@ -270,7 +270,8 @@ namespace ts.server {
             public readonly cancellationToken: HostCancellationToken,
             public readonly useSingleInferredProject: boolean,
             readonly typingsInstaller: ITypingsInstaller = nullTypingsInstaller,
-            private readonly eventHandler?: ProjectServiceEventHandler) {
+            private readonly eventHandler?: ProjectServiceEventHandler,
+            public readonly throttleWaitMilliseconds?: number) {
 
             Debug.assert(!!host.createHash, "'ServerHost.createHash' is required for ProjectService");
 

src/server/lsHost.ts

@@ -16,6 +16,7 @@ namespace ts.server {
         readonly realpath?: (path: string) => string;
 
         constructor(private readonly host: ServerHost, private readonly project: Project, private readonly cancellationToken: HostCancellationToken) {
+            this.cancellationToken = new ThrottledCancellationToken(cancellationToken, project.projectService.throttleWaitMilliseconds);
             this.getCanonicalFileName = ts.createGetCanonicalFileName(this.host.useCaseSensitiveFileNames);
 
             if (host.trace) {

src/server/session.ts

@@ -338,7 +338,8 @@ namespace ts.server {
             private hrtime: (start?: number[]) => number[],
             protected logger: Logger,
             protected readonly canUseEvents: boolean,
-            eventHandler?: ProjectServiceEventHandler) {
+            eventHandler?: ProjectServiceEventHandler,
+            private readonly throttleWaitMilliseconds?: number) {
 
             this.eventHander = canUseEvents
                 ? eventHandler || (event => this.defaultEventHandler(event))
@@ -353,7 +354,7 @@ namespace ts.server {
                 isCancellationRequested: () => cancellationToken.isCancellationRequested()
             }
             this.errorCheck = new MultistepOperation(multistepOperationHost);
-            this.projectService = new ProjectService(host, logger, cancellationToken, useSingleInferredProject, typingsInstaller, this.eventHander);
+            this.projectService = new ProjectService(host, logger, cancellationToken, useSingleInferredProject, typingsInstaller, this.eventHander, this.throttleWaitMilliseconds);
             this.gcTimer = new GcTimer(host, /*delay*/ 7000, logger);
         }
 

src/services/navigationBar.ts

@@ -2,6 +2,36 @@
 
 /* @internal */
 namespace ts.NavigationBar {
+    /**
+     * Matches all whitespace characters in a string. Eg:
+     *
+     * "app.
+     *
+     * onactivated"
+     *
+     * matches because of the newline, whereas
+     *
+     * "app.onactivated"
+     *
+     * does not match.
+     */
+    const whiteSpaceRegex = /\s+/g;
+
+    // Keep sourceFile handy so we don't have to search for it every time we need to call `getText`.
+    let curCancellationToken: CancellationToken;
+    let curSourceFile: SourceFile;
+
+    /**
+     * For performance, we keep navigation bar parents on a stack rather than passing them through each recursion.
+     * `parent` is the current parent and is *not* stored in parentsStack.
+     * `startNode` sets a new parent and `endNode` returns to the previous parent.
+     */
+    let parentsStack: NavigationBarNode[] = [];
+    let parent: NavigationBarNode;
+
+    // NavigationBarItem requires an array, but will not mutate it, so just give it this for performance.
+    let emptyChildItemArray: NavigationBarItem[] = [];
+
     /**
      * Represents a navigation bar item and its children.
      * The returned NavigationBarItem is more complicated and doesn't include 'parent', so we use these to do work before converting.
@@ -21,8 +51,7 @@ namespace ts.NavigationBar {
             return map(topLevelItems(rootNavigationBarNode(sourceFile)), convertToTopLevelItem);
         }
         finally {
-            curSourceFile = undefined;
-            curCancellationToken = undefined;
+            reset();
         }
     }
 
@@ -33,14 +62,18 @@ namespace ts.NavigationBar {
             return convertToTree(rootNavigationBarNode(sourceFile));
         }
         finally {
-            curSourceFile = undefined;
-            curCancellationToken = undefined;
+            reset();
         }
     }
 
-    // Keep sourceFile handy so we don't have to search for it every time we need to call `getText`.
-    let curCancellationToken: CancellationToken;
-    let curSourceFile: SourceFile;
+    function reset() {
+        curSourceFile = undefined;
+        curCancellationToken = undefined;
+        parentsStack = [];
+        parent = undefined;
+        emptyChildItemArray = [];
+    }
+
     function nodeText(node: Node): string {
         return node.getText(curSourceFile);
     }
@@ -58,14 +91,6 @@ namespace ts.NavigationBar {
         }
     }
 
-    /*
-    For performance, we keep navigation bar parents on a stack rather than passing them through each recursion.
-    `parent` is the current parent and is *not* stored in parentsStack.
-    `startNode` sets a new parent and `endNode` returns to the previous parent.
-    */
-    const parentsStack: NavigationBarNode[] = [];
-    let parent: NavigationBarNode;
-
     function rootNavigationBarNode(sourceFile: SourceFile): NavigationBarNode {
         Debug.assert(!parentsStack.length);
         const root: NavigationBarNode = { node: sourceFile, additionalNodes: undefined, parent: undefined, children: undefined, indent: 0 };
@@ -500,9 +525,6 @@ namespace ts.NavigationBar {
         }
     }
 
-    // NavigationBarItem requires an array, but will not mutate it, so just give it this for performance.
-    const emptyChildItemArray: NavigationBarItem[] = [];
-
     function convertToTree(n: NavigationBarNode): NavigationTree {
         return {
             text: getItemName(n.node),
@@ -623,19 +645,4 @@ namespace ts.NavigationBar {
     function isFunctionOrClassExpression(node: Node): boolean {
         return node.kind === SyntaxKind.FunctionExpression || node.kind === SyntaxKind.ArrowFunction || node.kind === SyntaxKind.ClassExpression;
     }
-
-    /**
-     * Matches all whitespace characters in a string. Eg:
-     *
-     * "app.
-     *
-     * onactivated"
-     *
-     * matches because of the newline, whereas
-     *
-     * "app.onactivated"
-     *
-     * does not match.
-     */
-    const whiteSpaceRegex = /\s+/g;
 }

src/services/services.ts

@@ -972,6 +972,36 @@ namespace ts {
         }
     }
 
+    /* @internal */
+    /** A cancellation that throttles calls to the host */
+    export class ThrottledCancellationToken implements CancellationToken {
+        // Store when we last tried to cancel.  Checking cancellation can be expensive (as we have
+        // to marshall over to the host layer).  So we only bother actually checking once enough
+        // time has passed.
+        private lastCancellationCheckTime = 0;
+
+        constructor(private hostCancellationToken: HostCancellationToken, private readonly throttleWaitMilliseconds = 20) {
+        }
+
+        public isCancellationRequested(): boolean {
+            const time = timestamp();
+            const duration = Math.abs(time - this.lastCancellationCheckTime);
+            if (duration >= this.throttleWaitMilliseconds) {
+                // Check no more than once every throttle wait milliseconds
+                this.lastCancellationCheckTime = time;
+                return this.hostCancellationToken.isCancellationRequested();
+            }
+
+            return false;
+        }
+
+        public throwIfCancellationRequested(): void {
+            if (this.isCancellationRequested()) {
+                throw new OperationCanceledException();
+            }
+        }
+    }
+
     export function createLanguageService(host: LanguageServiceHost,
         documentRegistry: DocumentRegistry = createDocumentRegistry(host.useCaseSensitiveFileNames && host.useCaseSensitiveFileNames(), host.getCurrentDirectory())): LanguageService {
 

src/services/shims.ts

@@ -469,29 +469,6 @@ namespace ts {
         }
     }
 
-    /** A cancellation that throttles calls to the host */
-    class ThrottledCancellationToken implements HostCancellationToken {
-        // Store when we last tried to cancel.  Checking cancellation can be expensive (as we have
-        // to marshall over to the host layer).  So we only bother actually checking once enough
-        // time has passed.
-        private lastCancellationCheckTime = 0;
-
-        constructor(private hostCancellationToken: HostCancellationToken) {
-        }
-
-        public isCancellationRequested(): boolean {
-            const time = timestamp();
-            const duration = Math.abs(time - this.lastCancellationCheckTime);
-            if (duration > 10) {
-                // Check no more than once every 10 ms.
-                this.lastCancellationCheckTime = time;
-                return this.hostCancellationToken.isCancellationRequested();
-            }
-
-            return false;
-        }
-    }
-
     export class CoreServicesShimHostAdapter implements ParseConfigHost, ModuleResolutionHost {
 
         public directoryExists: (directoryName: string) => boolean;