From b54d481fc8f8f30885382cb4ec1d92aa2b06b551 Mon Sep 17 00:00:00 2001
From: Mateusz Kwasniewski <kwasniewski.mateusz@gmail.com>
Date: Mon, 30 Oct 2023 12:38:32 +0100
Subject: [PATCH] fix: variant hashing in playground (#5213)

---
 .../strategy/flexible-rollout-strategy.ts     |  4 ++--
 .../strategy/gradual-rollout-session-id.ts    |  4 ++--
 .../strategy/gradual-rollout-user-id.ts       |  4 ++--
 .../feature-evaluator/strategy/util.ts        | 24 ++++++++++++++++---
 .../playground/feature-evaluator/variant.ts   |  4 ++--
 5 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/src/lib/features/playground/feature-evaluator/strategy/flexible-rollout-strategy.ts b/src/lib/features/playground/feature-evaluator/strategy/flexible-rollout-strategy.ts
index 97da0f04e7..728bdec61f 100644
--- a/src/lib/features/playground/feature-evaluator/strategy/flexible-rollout-strategy.ts
+++ b/src/lib/features/playground/feature-evaluator/strategy/flexible-rollout-strategy.ts
@@ -1,6 +1,6 @@
 import { Strategy } from './strategy';
 import { Context } from '../context';
-import normalizedValue from './util';
+import { normalizedStrategyValue } from './util';
 import { resolveContextValue } from '../helpers';
 
 const STICKINESS = {
@@ -54,7 +54,7 @@ export default class FlexibleRolloutStrategy extends Strategy {
         if (!stickinessId) {
             return false;
         }
-        const normalizedUserId = normalizedValue(stickinessId, groupId);
+        const normalizedUserId = normalizedStrategyValue(stickinessId, groupId);
         return percentage > 0 && normalizedUserId <= percentage;
     }
 }
diff --git a/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-session-id.ts b/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-session-id.ts
index 391c5b62c1..3ea08d7502 100644
--- a/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-session-id.ts
+++ b/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-session-id.ts
@@ -1,5 +1,5 @@
 import { Strategy } from './strategy';
-import normalizedValue from './util';
+import { normalizedStrategyValue } from './util';
 import { Context } from '../context';
 
 export default class GradualRolloutSessionIdStrategy extends Strategy {
@@ -19,7 +19,7 @@ export default class GradualRolloutSessionIdStrategy extends Strategy {
         const percentage = Number(parameters.percentage);
         const groupId = parameters.groupId || '';
 
-        const normalizedId = normalizedValue(sessionId, groupId);
+        const normalizedId = normalizedStrategyValue(sessionId, groupId);
 
         return percentage > 0 && normalizedId <= percentage;
     }
diff --git a/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-user-id.ts b/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-user-id.ts
index e4edd7ca82..f31325a4d0 100644
--- a/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-user-id.ts
+++ b/src/lib/features/playground/feature-evaluator/strategy/gradual-rollout-user-id.ts
@@ -1,6 +1,6 @@
 import { Strategy } from './strategy';
 import { Context } from '../context';
-import normalizedValue from './util';
+import { normalizedStrategyValue } from './util';
 
 export default class GradualRolloutUserIdStrategy extends Strategy {
     constructor() {
@@ -19,7 +19,7 @@ export default class GradualRolloutUserIdStrategy extends Strategy {
         const percentage = Number(parameters.percentage);
         const groupId = parameters.groupId || '';
 
-        const normalizedUserId = normalizedValue(userId, groupId);
+        const normalizedUserId = normalizedStrategyValue(userId, groupId);
 
         return percentage > 0 && normalizedUserId <= percentage;
     }
diff --git a/src/lib/features/playground/feature-evaluator/strategy/util.ts b/src/lib/features/playground/feature-evaluator/strategy/util.ts
index c3ce7434ed..4c7cef05df 100644
--- a/src/lib/features/playground/feature-evaluator/strategy/util.ts
+++ b/src/lib/features/playground/feature-evaluator/strategy/util.ts
@@ -1,9 +1,27 @@
 import * as murmurHash3 from 'murmurhash3js';
 
-export default function normalizedValue(
+function normalizedValue(
     id: string,
     groupId: string,
-    normalizer = 100,
+    normalizer: number,
+    seed = 0,
 ): number {
-    return (murmurHash3.x86.hash32(`${groupId}:${id}`) % normalizer) + 1;
+    const hash = murmurHash3.x86.hash32(`${groupId}:${id}`, seed);
+    return (hash % normalizer) + 1;
+}
+
+const STRATEGY_SEED = 0;
+
+export function normalizedStrategyValue(id: string, groupId: string): number {
+    return normalizedValue(id, groupId, 100, STRATEGY_SEED);
+}
+
+const VARIANT_SEED = 86028157;
+
+export function normalizedVariantValue(
+    id: string,
+    groupId: string,
+    normalizer: number,
+): number {
+    return normalizedValue(id, groupId, normalizer, VARIANT_SEED);
 }
diff --git a/src/lib/features/playground/feature-evaluator/variant.ts b/src/lib/features/playground/feature-evaluator/variant.ts
index 6784836b2e..3630e8e745 100644
--- a/src/lib/features/playground/feature-evaluator/variant.ts
+++ b/src/lib/features/playground/feature-evaluator/variant.ts
@@ -1,7 +1,7 @@
 import { Context } from './context';
 // eslint-disable-next-line import/no-cycle
 import { FeatureInterface } from './feature';
-import normalizedValue from './strategy/util';
+import { normalizedVariantValue } from './strategy/util';
 import { resolveContextValue } from './helpers';
 
 interface Override {
@@ -91,7 +91,7 @@ export function selectVariantDefinition(
 
     const { stickiness } = variants[0];
 
-    const target = normalizedValue(
+    const target = normalizedVariantValue(
         getSeed(context, stickiness),
         featureName,
         totalWeight,