simplify murmurhash, fix test

amplitude · Sep 20, 2023 · efc50bd · efc50bd
1 parent cc30f88
commit efc50bd
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Showing 3 changed files with 16 additions and 14 deletions.
diff --git a/evaluation-core/src/commonMain/kotlin/Murmur3.kt b/evaluation-core/src/commonMain/kotlin/Murmur3.kt
@@ -78,19 +78,12 @@ internal object Murmur3 {
         return hashResult
     }
 
-    private fun Int.reverseBytes(): Int {
-        return (this and -0x1000000 ushr 24) or
-            (this and 0x00ff0000 ushr 8) or
-            (this and 0x0000ff00 shl 8) or
-            (this and 0x000000ff shl 24)
-    }
-
     private fun ByteArray.readIntLe(index: Int = 0): Int {
         return (
-            this[index].toInt() and 0xff shl 24
-                or (this[index + 1].toInt() and 0xff shl 16)
-                or (this[index + 2].toInt() and 0xff shl 8)
-                or (this[index + 3].toInt() and 0xff)
-            ).reverseBytes()
+            this[index].toInt() and 0xff
+                or (this[index + 1].toInt() and 0xff shl 8)
+                or (this[index + 2].toInt() and 0xff shl 16)
+                or (this[index + 3].toInt() and 0xff shl 24)
+            )
     }
 }
diff --git a/evaluation-core/src/commonTest/kotlin/EvaluationIntegrationTest.kt b/evaluation-core/src/commonTest/kotlin/EvaluationIntegrationTest.kt
@@ -318,8 +318,8 @@ class EvaluationIntegrationTest {
 
     @Test
     fun `test device id bucketing`() {
-        val user = userContext(userId = "device_id")
-        val result = engine.evaluate(user, flags)["test-user-id-bucketing"]
+        val user = userContext(deviceId = "device_id")
+        val result = engine.evaluate(user, flags)["test-device-id-bucketing"]
         DefaultAsserter.assertEquals(
             "Unexpected evaluation result",
             "on",

diff --git a/evaluation-core/src/commonTest/kotlin/MurMurEnglishTest.kt b/evaluation-core/src/commonTest/kotlin/MurMurEnglishTest.kt
@@ -2,6 +2,7 @@ package com.amplitude.experiment.evaluation
 
 import com.amplitude.experiment.evaluation.util.ENGLISH_WORDS
 import com.amplitude.experiment.evaluation.util.HASH3_X86_32
+import io.ktor.utils.io.core.toByteArray
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
@@ -15,6 +16,14 @@ class Murmur3Test {
     private val englishWords = ENGLISH_WORDS.trim()
     private val hash3X8632 = HASH3_X86_32.trim()
 
+    @Test
+    fun testMurMur3HashSimple() {
+        val input = "brian".toByteArray()
+        val result = Murmur3.hash32x86(input, input.size, MURMUR_SEED).toLong()
+        val expected = (3948467465 and 0xffffffff)
+        assertEquals(3948467465, expected)
+    }
+
     @Test
     fun testEnglishWordsMurmur3_x86_32() {
         testHashes(object : StringHashFunction {