Refactor redisReceiver to eliminate global state and prevent memory leaks

[AbanoubGhadban]

Problem

The redisReceiver.ts module in the dummy app currently uses global module-level state that causes several issues:

Global State Issues

1. Shared Redis Client - Single sharedRedisClient connection shared across ALL concurrent requests
2. Global pendingPromises Map - Promise tracking map shared across ALL listeners, regardless of requestId
3. Global activeListeners Map - Listener cache that accumulates undefined entries (never cleaned up properly)

Memory Leak Risk

• pendingPromises and activeListeners maps only set entries to undefined instead of deleting them
• Over time in long-running processes, these maps accumulate undefined entries
• Global state prevents proper garbage collection between requests

Request Isolation Issues

• Multiple concurrent requests share the same Redis client connection
• pendingPromises being global means different requestIds can interfere with each other's promise resolution
• No proper isolation between independent stream listeners

Solution

Refactor to eliminate all global state by moving to request-scoped encapsulation:

Changes

1. Remove all module-level state variables:

   • sharedRedisClient ❌
   • isClientConnected ❌
   • activeListeners ❌
   • pendingPromises ❌

2. Create private state per listenToRequestData() call:

   • Each listener gets its own dedicated Redis client instance
   • Each listener has its own isolated pendingPromises map
   • Each listener manages its own connection lifecycle

3. Proper cleanup:

   • Use delete instead of setting to undefined
   • Always close Redis client in close() method
   • Clear all Maps completely on cleanup

Benefits

✅ No memory leaks - All state properly cleaned up per request
✅ Request isolation - Each stream listener is completely independent
✅ Simpler code - No global state management complexity
✅ Better resource management - Each listener owns its connection lifecycle
✅ Same API - No breaking changes to consumers

Scope

Files modified:

• /react_on_rails_pro/spec/dummy/client/app/utils/redisReceiver.ts - Internal refactoring only

No changes needed:

• Consumer components (RedisReceiver.jsx, RSCPostsPageOverRedis.jsx)
• E2E tests
• Backend Ruby controllers

Behavioral differences:

• Removed listener caching by requestId (each call creates fresh listener)
• Each listener has isolated state and own Redis connection
• External API and behavior unchanged