ref(flags): Refactor LaunchDarkly integration to reusable functions

Moves core logic into re-usable functions so that we can re-use for other integrations.

Author: billyvg

packages/browser/src/integrations/featureFlags/launchdarkly/integration.ts

@@ -1,8 +1,8 @@
 import type { Client, Event, EventHint, IntegrationFn } from '@sentry/types';
 import type { LDContext, LDEvaluationDetail, LDInspectionFlagUsedHandler } from './types';
 
-import { defineIntegration, getCurrentScope } from '@sentry/core';
-import { insertToFlagBuffer } from '../../../utils/featureFlags';
+import { defineIntegration } from '@sentry/core';
+import { copyFlagsFromScopeToEvent, insertToFlagBuffer } from '../../../utils/featureFlags';
 
 /**
  * Sentry integration for capturing feature flags from LaunchDarkly.
@@ -24,15 +24,7 @@ export const launchDarklyIntegration = defineIntegration(() => {
     name: 'LaunchDarkly',
 
     processEvent(event: Event, _hint: EventHint, _client: Client): Event {
-      const scope = getCurrentScope();
-      const flagContext = scope.getScopeData().contexts.flags;
-      const flagBuffer = flagContext ? flagContext.values : [];
-
-      if (event.contexts === undefined) {
-        event.contexts = {};
-      }
-      event.contexts.flags = { values: [...flagBuffer] };
-      return event;
+      return copyFlagsFromScopeToEvent(event);
     },
   };
 }) satisfies IntegrationFn;
@@ -54,15 +46,7 @@ export function buildLaunchDarklyFlagUsedHandler(): LDInspectionFlagUsedHandler
      * Handle a flag evaluation by storing its name and value on the current scope.
      */
     method: (flagKey: string, flagDetail: LDEvaluationDetail, _context: LDContext) => {
-      if (typeof flagDetail.value === 'boolean') {
-        const scopeContexts = getCurrentScope().getScopeData().contexts;
-        if (!scopeContexts.flags) {
-          scopeContexts.flags = { values: [] };
-        }
-        const flagBuffer = scopeContexts.flags.values;
-        insertToFlagBuffer(flagBuffer, flagKey, flagDetail.value);
-      }
-      return;
+      insertToFlagBuffer(flagKey, flagDetail.value);
     },
   };
 }

packages/browser/src/utils/featureFlags.ts

@@ -1,4 +1,5 @@
-import type { FeatureFlag } from '@sentry/types';
+import { getCurrentScope } from '@sentry/core';
+import type { Event, FeatureFlag } from '@sentry/types';
 import { logger } from '@sentry/utils';
 import { DEBUG_BUILD } from '../debug-build';
 
@@ -13,6 +14,21 @@ import { DEBUG_BUILD } from '../debug-build';
  */
 export const FLAG_BUFFER_SIZE = 100;
 
+/**
+ * Copies feature flags that are in current scope context to the event context
+ */
+export function copyFlagsFromScopeToEvent(event: Event): Event {
+  const scope = getCurrentScope();
+  const flagContext = scope.getScopeData().contexts.flags;
+  const flagBuffer = flagContext ? flagContext.values : [];
+
+  if (event.contexts === undefined) {
+    event.contexts = {};
+  }
+  event.contexts.flags = { values: [...flagBuffer] };
+  return event;
+}
+
 /**
  * Insert into a FeatureFlag array while maintaining ordered LRU properties. Not
  * thread-safe. After inserting:
@@ -21,18 +37,23 @@ export const FLAG_BUFFER_SIZE = 100;
  * - The length of `flags` does not exceed `maxSize`. The oldest flag is evicted
  *  as needed.
  *
- * @param flags    The array to insert into.
  * @param name     Name of the feature flag to insert.
  * @param value    Value of the feature flag.
  * @param maxSize  Max number of flags the buffer should store. It's recommended
  *   to keep this consistent across insertions. Default is DEFAULT_MAX_SIZE
  */
-export function insertToFlagBuffer(
-  flags: FeatureFlag[],
-  name: string,
-  value: boolean,
-  maxSize: number = FLAG_BUFFER_SIZE,
-): void {
+export function insertToFlagBuffer(name: string, value: unknown, maxSize: number = FLAG_BUFFER_SIZE): void {
+  // Currently only accepts boolean values
+  if (typeof value !== 'boolean') {
+    return;
+  }
+
+  const scopeContexts = getCurrentScope().getScopeData().contexts;
+  if (!scopeContexts.flags) {
+    scopeContexts.flags = { values: [] };
+  }
+  const flags = scopeContexts.flags.values as FeatureFlag[];
+
   if (flags.length > maxSize) {
     DEBUG_BUILD && logger.error(`[Feature Flags] insertToFlagBuffer called on a buffer larger than maxSize=${maxSize}`);
     return;