refactor(debounce): avoid reimplementations of the same logic.

[Hweinstock]

Problem

debounce is reimplemented in multiple places. There is debounce:

aws-toolkit-vscode/packages/core/src/shared/utilities/functionUtils.ts

Lines 89 to 108 in 100eb07

	export function debounce<T>(cb: () => T | Promise<T>, delay: number = 0): () => Promise<T> {
	let timeout: Timeout | undefined
	let promise: Promise<T> | undefined
	return () => {
	timeout?.refresh()
	return (promise ??= new Promise<T>((resolve, reject) => {
	timeout = new Timeout(delay)
	timeout.onCompletion(async () => {
	timeout = promise = undefined
	try {
	resolve(await cb())
	} catch (err) {
	reject(err)
	}
	})
	}))
	}
	}

cancellableDebounce:

aws-toolkit-vscode/packages/core/src/shared/utilities/functionUtils.ts

Lines 114 to 147 in 100eb07

	export function cancellableDebounce<T, U extends any[]>(
	cb: (...args: U) => T | Promise<T>,
	delay: number = 0
	): { promise: (...args: U) => Promise<T>; cancel: () => void } {
	let timeout: Timeout | undefined
	let promise: Promise<T> | undefined
	const cancel = (): void => {
	if (timeout) {
	timeout.cancel()
	timeout = undefined
	promise = undefined
	}
	}
	return {
	promise: (...arg) => {
	timeout?.refresh()
	return (promise ??= new Promise<T>((resolve, reject) => {
	timeout = new Timeout(delay)
	timeout.onCompletion(async () => {
	timeout = promise = undefined
	try {
	resolve(await cb(...arg))
	} catch (err) {
	reject(err)
	}
	})
	}))
	},
	cancel: cancel,
	}
	}

and a very similar function keyedDebounce:

aws-toolkit-vscode/packages/core/src/auth/auth.ts

Lines 107 to 122 in 100eb07

	function keyedDebounce<T, U extends any[], K extends string = string>(
	fn: (key: K, ...args: U) => Promise<T>
	): typeof fn {
	const pending = new Map<K, Promise<T>>()
	return (key, ...args) => {
	if (pending.has(key)) {
	return pending.get(key)!
	}
	const promise = fn(key, ...args).finally(() => pending.delete(key))
	pending.set(key, promise)
	return promise
	}
	}

These functions should share common implementation logic, and live in the same place for easier discoverability.

Solution

• reimplement debounce in terms of cancellableDebounce since its a special case.
• move these functions to shared, common location.
• augment debounce to allow the callback to take arguments.

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
  • Confirm whether tests should be added or ensure the PR description explains why tests are not required.