[BEAM-13557] [Playground] show code execution time

[ElessarST]

Added code execution time to the UI.

Screen.Recording.2021-12-27.at.15.57.57.mov

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ValidatesRunner compliance status (on master branch)

Lang	ULR	Dataflow	Flink	Samza	Spark	Twister2
Go	---					---
Java
Python	---					---
XLang						---

Examples testing status on various runners

Lang	ULR	Dataflow	Flink	Samza	Spark	Twister2
Go	---	---	---	---	---	---	---
Java	---		---	---	---	---	---
Python	---	---	---	---	---	---	---
XLang	---	---	---	---	---	---	---

Post-Commit SDK/Transform Integration Tests Status (on master branch)

Go	Java	Python

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website	Whitespace	Typescript
Non-portable
Portable	---			---	---	---

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GitHub Actions Tests Status (on master branch)

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[KonradJanica]

Redundant question mark or null check.

[ElessarST]

question mark is required, because timer is not local variable

[KonradJanica]

The question mark is just a shorthand null check, so this code compiles to:

if (timer != null) {
if (timer != null) {
timer.cancel();
}
}

[KonradJanica]

Perhaps add _executionTime?.close() above this line to prevent a memory leak. I'm concerned about the circular reference inside the stopTimer and tick methods. Normally circular references are fine in JavaScript, but in this case, the setTimeout loop might cause issues.

[KonradJanica]

The question mark is just a shorthand null check, so this code compiles to:

if (timer != null) {
if (timer != null) {
timer.cancel();
}
}

[pabloem]

@ElessarST I'm happy to merge, or wait for addressing the question mark issue

[ElessarST]

@ElessarST I'm happy to merge, or wait for addressing the question mark issue

Hi @pabloem , I removed the null check and left only question mark, could you please merge?

[pabloem]

lgtm