From 3a029b8e80b98930b64894831d77f86089c04dc4 Mon Sep 17 00:00:00 2001
From: Ilya Gorbunov <ilya.gorbunov@jetbrains.com>
Date: Thu, 30 Jun 2022 02:09:37 +0300
Subject: [PATCH] Fix ValueTimeMark adjustment in rare cases and properly test
 it

---
 .../src/kotlin/time/longSaturatedMath.kt      | 14 ++++++++-----
 libraries/stdlib/test/time/TimeMarkTest.kt    | 20 +++++++++++--------
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/libraries/stdlib/src/kotlin/time/longSaturatedMath.kt b/libraries/stdlib/src/kotlin/time/longSaturatedMath.kt
index cb526891001..c04782d8e9d 100644
--- a/libraries/stdlib/src/kotlin/time/longSaturatedMath.kt
+++ b/libraries/stdlib/src/kotlin/time/longSaturatedMath.kt
@@ -12,10 +12,10 @@ import kotlin.time.Duration.Companion.nanoseconds
 
 internal fun saturatingAdd(longNs: Long, duration: Duration): Long {
     val durationNs = duration.inWholeNanoseconds
-    if ((longNs - 1) or 1 == Long.MAX_VALUE) { // MIN_VALUE or MAX_VALUE - the reading is infinite
+    if (longNs.isSaturated()) { // MIN_VALUE or MAX_VALUE - the reading is infinite
         return checkInfiniteSumDefined(longNs, duration, durationNs)
     }
-    if ((durationNs - 1) or 1 == Long.MAX_VALUE) { // duration doesn't fit in Long nanos
+    if (durationNs.isSaturated()) { // duration doesn't fit in Long nanos
         return saturatingAddInHalves(longNs, duration)
     }
 
@@ -33,16 +33,16 @@ private fun checkInfiniteSumDefined(longNs: Long, duration: Duration, durationNs
 
 private fun saturatingAddInHalves(longNs: Long, duration: Duration): Long {
     val half = duration / 2
-    if ((half.inWholeNanoseconds - 1) or 1 == Long.MAX_VALUE) {
+    if (half.inWholeNanoseconds.isSaturated()) {
         // this will definitely saturate
         return (longNs + duration.toDouble(DurationUnit.NANOSECONDS)).toLong()
     } else {
-        return saturatingAdd(saturatingAdd(longNs, half), half)
+        return saturatingAdd(saturatingAdd(longNs, half), duration - half)
     }
 }
 
 internal fun saturatingDiff(valueNs: Long, originNs: Long): Duration {
-    if ((originNs - 1) or 1 == Long.MAX_VALUE) { // MIN_VALUE or MAX_VALUE
+    if (originNs.isSaturated()) { // MIN_VALUE or MAX_VALUE
         return -(originNs.toDuration(DurationUnit.DAYS)) // saturate to infinity
     }
     val result = valueNs - originNs
@@ -53,3 +53,7 @@ internal fun saturatingDiff(valueNs: Long, originNs: Long): Duration {
     }
     return result.nanoseconds
 }
+
+@Suppress("NOTHING_TO_INLINE")
+private inline fun Long.isSaturated(): Boolean =
+    (this - 1) or 1 == Long.MAX_VALUE // == either MAX_VALUE or MIN_VALUE
diff --git a/libraries/stdlib/test/time/TimeMarkTest.kt b/libraries/stdlib/test/time/TimeMarkTest.kt
index 3a740595f69..6dd650f2656 100644
--- a/libraries/stdlib/test/time/TimeMarkTest.kt
+++ b/libraries/stdlib/test/time/TimeMarkTest.kt
@@ -75,13 +75,15 @@ class TimeMarkTest {
 
 
         val longDuration = Long.MAX_VALUE.nanoseconds
-        val long2Duration = longDuration * 2
+        val long2Duration = longDuration + 1001.milliseconds
 
         val pastMark = baseMark - longDuration
         val futureMark = pastMark + long2Duration
-        val sameMark = futureMark - longDuration
-        val elapsedDiff = sameMark.elapsedNow() - baseMark.elapsedNow()
-        assertTrue(elapsedDiff < 1.milliseconds, "$elapsedDiff")
+        val sameMark = futureMark - (long2Duration - longDuration)
+
+        val elapsedDiff = (sameMark.elapsedNow() - baseMark.elapsedNow()).absoluteValue
+        val elapsedDiff2 = (baseMark.elapsedNow() - sameMark.elapsedNow()).absoluteValue
+        assertTrue(maxOf(elapsedDiff, elapsedDiff2) < 1.milliseconds, "$elapsedDiff, $elapsedDiff2")
     }
 
     @Test
@@ -144,12 +146,14 @@ class TimeMarkTest {
         assertFailsWith<IllegalArgumentException> { infinitePastMark + Duration.INFINITE }
 
         val longDuration = Long.MAX_VALUE.nanoseconds
-        val long2Duration = longDuration * 2
+        val long2Duration = longDuration + 1001.milliseconds
 
         val pastMark = baseMark - longDuration
         val futureMark = pastMark + long2Duration
-        val sameMark = futureMark - longDuration
-        val elapsedDiff = sameMark.elapsedNow() - baseMark.elapsedNow()
-        assertTrue(elapsedDiff < 1.milliseconds, "$elapsedDiff")
+        val sameMark = futureMark - (long2Duration - longDuration)
+
+        val elapsedDiff = (sameMark.elapsedNow() - baseMark.elapsedNow()).absoluteValue
+        val elapsedDiff2 = (baseMark.elapsedNow() - sameMark.elapsedNow()).absoluteValue
+        assertTrue(maxOf(elapsedDiff, elapsedDiff2) < 1.milliseconds, "$elapsedDiff, $elapsedDiff2")
     }
 }