From 58d2e003bca861d5b164b2afe6566f54005cbd47 Mon Sep 17 00:00:00 2001
From: Paul D'Ambra <paul@posthog.com>
Date: Thu, 31 Oct 2024 19:59:42 +0100
Subject: [PATCH] feat: allow mutation rate limiter configuration (#1506)

---
 src/extensions/replay/mutation-rate-limiter.ts | 15 +++++++++++++--
 src/extensions/replay/sessionrecording.ts      |  2 ++
 src/types.ts                                   | 14 ++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/extensions/replay/mutation-rate-limiter.ts b/src/extensions/replay/mutation-rate-limiter.ts
index a85416cc5..4c515ebc2 100644
--- a/src/extensions/replay/mutation-rate-limiter.ts
+++ b/src/extensions/replay/mutation-rate-limiter.ts
@@ -1,5 +1,6 @@
 import type { eventWithTime, mutationCallbackParam } from '@rrweb/types'
 import { INCREMENTAL_SNAPSHOT_EVENT_TYPE, MUTATION_SOURCE_TYPE, rrwebRecord } from './sessionrecording-utils'
+import { clampToRange } from '../../utils/number-utils'
 
 export class MutationRateLimiter {
     private bucketSize = 100
@@ -15,8 +16,18 @@ export class MutationRateLimiter {
             onBlockedNode?: (id: number, node: Node | null) => void
         } = {}
     ) {
-        this.refillRate = this.options.refillRate ?? this.refillRate
-        this.bucketSize = this.options.bucketSize ?? this.bucketSize
+        this.refillRate = clampToRange(
+            this.options.refillRate ?? this.refillRate,
+            0,
+            100,
+            'mutation throttling refill rate'
+        )
+        this.bucketSize = clampToRange(
+            this.options.bucketSize ?? this.bucketSize,
+            0,
+            100,
+            'mutation throttling bucket size'
+        )
         setInterval(() => {
             this.refillBuckets()
         }, 1000)
diff --git a/src/extensions/replay/sessionrecording.ts b/src/extensions/replay/sessionrecording.ts
index 771976460..f46b64d8f 100644
--- a/src/extensions/replay/sessionrecording.ts
+++ b/src/extensions/replay/sessionrecording.ts
@@ -890,6 +890,8 @@ export class SessionRecording {
         this.mutationRateLimiter =
             this.mutationRateLimiter ??
             new MutationRateLimiter(this.rrwebRecord, {
+                refillRate: this.instance.config.session_recording.__mutationRateLimiterRefillRate,
+                bucketSize: this.instance.config.session_recording.__mutationRateLimiterBucketSize,
                 onBlockedNode: (id, node) => {
                     const message = `Too many mutations on node '${id}'. Rate limiting. This could be due to SVG animations or something similar`
                     logger.info(message, {
diff --git a/src/types.ts b/src/types.ts
index ea0674763..0f6c5cfc9 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -309,6 +309,20 @@ export interface SessionRecordingOptions {
      Default is 5 minutes.
     */
     session_idle_threshold_ms?: number
+    /*
+     ADVANCED: alters the refill rate for the token bucket mutation throttling
+     Normally only altered alongside posthog support guidance.
+     Accepts values between 0 and 100
+     Default is 10.
+    */
+    __mutationRateLimiterRefillRate?: number
+    /*
+     ADVANCED: alters the bucket size for the token bucket mutation throttling
+     Normally only altered alongside posthog support guidance.
+     Accepts values between 0 and 100
+     Default is 100.
+    */
+    __mutationRateLimiterBucketSize?: number
 }
 
 export type SessionIdChangedCallback = (