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Make FastRandom global instance thread-safe #1968

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merged 1 commit into from
Oct 24, 2023
Merged

Make FastRandom global instance thread-safe #1968

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13 changes: 6 additions & 7 deletions korge-foundation/src/common/korlibs/datastructure/_Datastructure_random.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -2,11 +2,8 @@

package korlibs.datastructure.random

import kotlin.native.concurrent.ThreadLocal
import kotlin.random.Random

@ThreadLocal
private val LocalFastRandom = FastRandom(Random.Default.nextLong())
import korlibs.datastructure.lock.*
import kotlin.random.*

// Copy of XorWowRandom from the Kotlin Standard library but optimizing some methods
open class FastRandom private constructor(
Expand All @@ -18,8 +15,10 @@ open class FastRandom private constructor(
private var addend: Int
) : Random() {
companion object : FastRandom() {
val Default get() = LocalFastRandom
override fun nextBits(bitCount: Int): Int = LocalFastRandom.nextBits(bitCount)
private val _instance = FastRandom(Random.Default.nextLong())
val Default: FastRandom get() = this
private val lock = Lock()
override fun nextBits(bitCount: Int): Int = lock { _instance.nextBits(bitCount) }
}

private constructor(seed1: Int, seed2: Int) :
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6 changes: 6 additions & 0 deletions korge-foundation/test/common/korlibs/datastructure/FastRandomTest.kt
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Expand Up @@ -82,4 +82,10 @@ class FastRandomTest {
assertEquals(3f, floatArrayOf(3f).random(random))
assertEquals(7.0, doubleArrayOf(7.0).random(random))
}

@Test
fun testGlobalInstance() {
println((0 until 10).map { FastRandom.nextInt() })
assertTrue { (0 until 10).map { FastRandom.nextInt() }.distinct().size >= 2 }
}
}