Instead of using Jvm bounded Timer, current TimerChannel is used with receiveAsFlow extension function.

Author: İbrahim Yilmaz

kotlinx-coroutines-core/jvm/src/flow/TickerFlow.kt

@@ -1,9 +1,11 @@
 package kotlinx.coroutines.flow
 
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.channels.TickerMode
+import kotlinx.coroutines.channels.ticker
 import java.util.*
-import kotlin.concurrent.schedule
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
 
 /**
  * Creates a flow that produces the first item after the given initial delay and subsequent items with the
@@ -13,21 +15,17 @@ import kotlin.concurrent.schedule
  *
  * This Flow stops producing elements immediately after [Job.cancel] invocation.
  *
- * @param period period between each element in milliseconds.
- * @param initialDelay delay after which the first element will be produced (it is equal to [period] by default) in milliseconds.
+ * @param delayMillis delay between each element in milliseconds.
+ * @param initialDelayMillis delay after which the first element will be produced (it is equal to [delayMillis] by default) in milliseconds.
+ * @param context context of the producing coroutine.
+ * @param mode specifies behavior when elements are not received ([FIXED_PERIOD][TickerMode.FIXED_PERIOD] by default).
  */
 public fun tickerFlow(
-        period: Long,
-        initialDelay: Long = period
-): Flow<Unit> = callbackFlow {
-    require(period > 0)
-    require(initialDelay > -1)
-
-    val timer = Timer()
-    timer.schedule(initialDelay, period) {
-        offer(Unit)
-    }
-
-    awaitClose { timer.cancel() }
-}
-
+        delayMillis: Long,
+        initialDelayMillis: Long = delayMillis,
+        context: CoroutineContext = EmptyCoroutineContext,
+        mode: TickerMode = TickerMode.FIXED_PERIOD
+): Flow<Unit> {
+    require(delayMillis > 0)
+    return ticker(delayMillis, initialDelayMillis, context, mode).receiveAsFlow()
+}

kotlinx-coroutines-core/jvm/test/flow/TickerFlowTest.kt

@@ -1,7 +1,6 @@
 package flow
 
 import kotlinx.coroutines.TestBase
-import kotlinx.coroutines.cancelAndJoin
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
@@ -37,17 +36,14 @@ class TickerFlowTest : TestBase() {
         val inbox = mutableListOf<Unit>()
 
         // WHEN
-        val periodicTicker =
-                tickerFlow(100, 100).onEach {
-                    inbox.add(Unit)
-                }.launchIn(this)
+        tickerFlow(100, 200).onEach {
+            inbox.add(Unit)
+        }.launchIn(this)
 
         delay(500)
 
         // THEN
         assertEquals(4, inbox.size)
-
-        periodicTicker.cancelAndJoin()
     }
 
     @Test
@@ -56,17 +52,14 @@ class TickerFlowTest : TestBase() {
         val inbox = mutableListOf<Unit>()
 
         // WHEN
-        val periodicTicker =
-                tickerFlow(100, 0).onEach {
-                    inbox.add(Unit)
-                }.launchIn(this)
+        tickerFlow(100, 0).onEach {
+            inbox.add(Unit)
+        }.launchIn(this)
 
         delay(500)
 
         // THEN
-        assertEquals(5, inbox.size)
-
-        periodicTicker.cancelAndJoin()
+        assertEquals(6, inbox.size)
     }
 
 
@@ -76,17 +69,14 @@ class TickerFlowTest : TestBase() {
         val inbox = mutableListOf<Unit>()
 
         // WHEN
-        val periodicTicker =
-                tickerFlow(100).onEach {
-                    inbox.add(Unit)
-                }.launchIn(this)
+        tickerFlow(100).onEach {
+            inbox.add(Unit)
+        }.launchIn(this)
 
         delay(500)
 
         // THEN
-        assertEquals(4, inbox.size)
-
-        periodicTicker.cancelAndJoin()
+        assertEquals(5, inbox.size)
     }
 
     @Test
@@ -106,6 +96,4 @@ class TickerFlowTest : TestBase() {
         // THEN
         assertEquals(0, inbox.size)
     }
-
-
 }