From 1769de903392ab14ffb6c366ab86dc24b5289e81 Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@users.noreply.github.com>
Date: Thu, 19 Nov 2020 18:07:51 -0300
Subject: [PATCH] feat(android): setInterval closer to web spec (#9044)

---
 apps/automated/src/timer/timer-tests.ts | 34 +++++++++++++++++++++++++
 packages/core/timer/index.android.ts    |  8 ++++--
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/apps/automated/src/timer/timer-tests.ts b/apps/automated/src/timer/timer-tests.ts
index 99c633828..4f8f10bbb 100644
--- a/apps/automated/src/timer/timer-tests.ts
+++ b/apps/automated/src/timer/timer-tests.ts
@@ -171,6 +171,40 @@ export function test_setInterval_callbackCalledWithExtraArgs(done) {
 	);
 }
 
+export function test_setInterval_callbackNotDelayedByBusyWork() {
+	let calls = 0;
+
+	let firstCall = true;
+	const id = timer.setInterval(() => {
+		calls++;
+		if (firstCall) {
+			firstCall = false;
+			TKUnit.wait(0.025);
+		}
+	}, 50);
+
+	TKUnit.wait(0.11);
+	timer.clearInterval(id);
+	TKUnit.assertEqual(calls, 2, 'Callback should be called multiple times with busy wait');
+}
+
+export function test_setInterval_callbackSkippedByBusyWork() {
+	let calls = 0;
+
+	let firstCall = true;
+	const id = timer.setInterval(() => {
+		calls++;
+		if (firstCall) {
+			firstCall = false;
+			TKUnit.wait(0.051);
+		}
+	}, 50);
+
+	TKUnit.wait(0.16);
+	timer.clearInterval(id);
+	TKUnit.assertEqual(calls, 2, 'Callback should be called skipped when it takes too long to process');
+}
+
 export function test_setInterval_callbackShouldBeCleared(done) {
 	const start = TKUnit.time();
 	// >> timer-set-interval
diff --git a/packages/core/timer/index.android.ts b/packages/core/timer/index.android.ts
index 06d42d958..8bf793113 100644
--- a/packages/core/timer/index.android.ts
+++ b/packages/core/timer/index.android.ts
@@ -58,12 +58,16 @@ export function setInterval(callback: Function, milliseconds = 0, ...args): numb
 	const handler = timeoutHandler;
 	const invoke = () => callback(...args);
 	const zoneBound = zonedCallback(invoke);
+	const startOffset = milliseconds > 0 ? Date.now() % milliseconds : 0;
+	function nextCallMs() {
+		return milliseconds > 0 ? milliseconds - ((Date.now() - startOffset) % milliseconds) : milliseconds;
+	}
 
 	const runnable = new java.lang.Runnable({
 		run: () => {
 			zoneBound();
 			if (timeoutCallbacks[id]) {
-				handler.postDelayed(runnable, long(milliseconds));
+				handler.postDelayed(runnable, long(nextCallMs()));
 			}
 		},
 	});
@@ -72,7 +76,7 @@ export function setInterval(callback: Function, milliseconds = 0, ...args): numb
 		timeoutCallbacks[id] = runnable;
 	}
 
-	timeoutHandler.postDelayed(runnable, long(milliseconds));
+	timeoutHandler.postDelayed(runnable, long(nextCallMs()));
 
 	return id;
 }