feat: add DisposableHandle and AsyncDisposableHandle

giladgd · Sep 17, 2024 · 3df1087 · 3df1087
1 parent 7c072ef
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diff --git a/README.md b/README.md
@@ -187,6 +187,92 @@ disposeAggregator.add(async () => {
 disposeAggregator.dispose();
 ```
 
+### `DisposableHandle`
+An object that provides a `.dispose()` method that can called only once.
+
+Calling `.dispose()` will call the provided `onDispose` function only once.
+Any subsequent calls to `.dispose()` will do nothing.
+
+```typescript
+import {DisposableHandle} from "lifecycle-utils";
+
+function createHandle() {
+    console.log("allocating resources");
+
+    return new DisposableHandle(() => {
+        console.log("resources disposed");
+    });
+}
+
+const handle = createHandle();
+handle.dispose();
+```
+
+Using the `using` feature of TypeScript is also supported:
+```typescript
+import {DisposableHandle} from "lifecycle-utils";
+
+function createHandle() {
+    console.log("allocating resources");
+
+    return new DisposableHandle(() => {
+        console.log("resources disposed");
+    });
+}
+
+function doWork() {
+    using handle = createHandle();
+}
+
+doWork();
+// resources disposed
+// the dispose function was called since the scope of the `doWork` function ended
+```
+
+### `AsyncDisposableHandle`
+An object that provides an async `.dispose()` method that can called only once.
+
+Calling `.dispose()` will call the provided `onDispose` function only once.
+Any subsequent calls to `.dispose()` will do nothing.
+
+```typescript
+import {AsyncDisposableHandle} from "lifecycle-utils";
+
+function createHandle() {
+    console.log("allocating resources");
+
+    return new AsyncDisposableHandle(async () => {
+        await new Promise(resolve => setTimeout(resolve, 1000));
+        console.log("resources disposed");
+    });
+}
+
+const handle = createHandle();
+await handle.dispose();
+```
+
+Using the `await using` feature of TypeScript is also supported:
+```typescript
+import {AsyncDisposableHandle} from "lifecycle-utils";
+
+function createHandle() {
+    console.log("allocating resources");
+
+    return new AsyncDisposableHandle(async () => {
+        await new Promise(resolve => setTimeout(resolve, 1000));
+        console.log("resources disposed");
+    });
+}
+
+async function doWork() {
+    await using handle = createHandle();
+}
+
+await doWork();
+// resources disposed
+// the dispose function was called since the scope of the `doWork` function ended
+```
+
 ### `MultiKeyMap`
 `MultiKeyMap` is a utility class that works like a `Map`, but accepts multiple values as the key for each value.
 

diff --git a/src/AsyncDisposableHandle.ts b/src/AsyncDisposableHandle.ts
@@ -0,0 +1,33 @@
+/**
+ * An object that provides an async `.dispose()` method that can called only once.
+ *
+ * Calling `.dispose()` will call the provided `onDispose` function only once.
+ * Any subsequent calls to `.dispose()` will do nothing.
+ */
+export class AsyncDisposableHandle {
+    /** @internal */ private _onDispose: (() => Promise<void>) | undefined;
+
+    public constructor(onDispose: () => Promise<void>) {
+        this._onDispose = onDispose;
+
+        this.dispose = this.dispose.bind(this);
+        this[Symbol.asyncDispose] = this[Symbol.asyncDispose].bind(this);
+    }
+
+    public get disposed() {
+        return this._onDispose == null;
+    }
+
+    public async [Symbol.asyncDispose]() {
+        await this.dispose();
+    }
+
+    public async dispose() {
+        if (this._onDispose != null) {
+            const onDispose = this._onDispose;
+            delete this._onDispose;
+
+            await onDispose();
+        }
+    }
+}
diff --git a/src/DisposableHandle.ts b/src/DisposableHandle.ts
@@ -0,0 +1,33 @@
+/**
+ * An object that provides a `.dispose()` method that can called only once.
+ *
+ * Calling `.dispose()` will call the provided `onDispose` function only once.
+ * Any subsequent calls to `.dispose()` will do nothing.
+ */
+export class DisposableHandle {
+    /** @internal */ private _onDispose: (() => void) | undefined;
+
+    public constructor(onDispose: () => void) {
+        this._onDispose = onDispose;
+
+        this.dispose = this.dispose.bind(this);
+        this[Symbol.dispose] = this[Symbol.dispose].bind(this);
+    }
+
+    public get disposed() {
+        return this._onDispose == null;
+    }
+
+    public [Symbol.dispose]() {
+        this.dispose();
+    }
+
+    public dispose() {
+        if (this._onDispose != null) {
+            const onDispose = this._onDispose;
+            delete this._onDispose;
+
+            onDispose();
+        }
+    }
+}
diff --git a/src/index.ts b/src/index.ts
@@ -4,6 +4,8 @@ export * from "./LongTimeout.js";
 export * from "./State.js";
 export * from "./DisposeAggregator.js";
 export * from "./AsyncDisposeAggregator.js";
+export * from "./DisposableHandle.js";
+export * from "./AsyncDisposableHandle.js";
 export * from "./MultiKeyMap.js";
 export * from "./splitText.js";
 export * from "./DisposedError.js";
diff --git a/test/AsyncDisposableHandle.test.ts b/test/AsyncDisposableHandle.test.ts
@@ -0,0 +1,77 @@
+import {describe, expect, test} from "vitest";
+import {AsyncDisposableHandle} from "../src/index.js";
+
+describe("AsyncDisposableHandle", () => {
+    test("disposing only happens once", async () => {
+        let disposeTimes = 0;
+        const handle = new AsyncDisposableHandle(async () => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        await handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        await handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+
+    test("marked as disposed before the callback finishes", async () => {
+        let disposeTimes = 0;
+        const handle = new AsyncDisposableHandle(async () => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        void handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        void handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+
+    test("Symbol.dispose works", async () => {
+        let disposeTimes = 0;
+        const handle = new AsyncDisposableHandle(async () => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        await handle[Symbol.asyncDispose]();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        await handle[Symbol.asyncDispose]();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+
+    test("Storing dispose function in a variable", () => {
+        let disposeTimes = 0;
+        const handle = new AsyncDisposableHandle(async () => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        const dispose = handle.dispose;
+        dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+});
diff --git a/test/DisposableHandle.test.ts b/test/DisposableHandle.test.ts
@@ -0,0 +1,59 @@
+import {describe, expect, test} from "vitest";
+import {DisposableHandle} from "../src/index.js";
+
+describe("DisposableHandle", () => {
+    test("disposing only happens once", () => {
+        let disposeTimes = 0;
+        const handle = new DisposableHandle(() => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        handle.dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+
+    test("Symbol.dispose works", () => {
+        let disposeTimes = 0;
+        const handle = new DisposableHandle(() => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        handle[Symbol.dispose]();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        handle[Symbol.dispose]();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+
+    test("Storing dispose function in a variable", () => {
+        let disposeTimes = 0;
+        const handle = new DisposableHandle(() => {
+            disposeTimes++;
+        });
+
+        expect(disposeTimes).toBe(0);
+        expect(handle.disposed).toBe(false);
+
+        const dispose = handle.dispose;
+        dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+
+        dispose();
+        expect(disposeTimes).toBe(1);
+        expect(handle.disposed).toBe(true);
+    });
+});