Changes to affect disconnect stability

[adamb3ll]

Summary

Enhanced the WebSockets library with ESP32-specific optimisations to prevent pbuf_free crashes and improve connection stability.

Changes Made

1. Enhanced dropNativeClient() Function

• Added buffer cleanup timing for ESP32
• Implemented 10ms delay before tcp->stop() to allow pending network operations to complete
• Added 5ms delay after stop for additional cleanup time
• Added yield() calls to prevent blocking during cleanup

2. Improved clientDisconnect() Function

• Added safety checks before calling dropNativeClient()
• Ensured network operations complete before cleanup
• Added yield() to prevent race conditions

3. Enhanced clientIsConnected() Function

• Added 5ms delays before disconnection calls to prevent rapid disconnection events
• Improved timing to prevent overwhelming the network stack
• Added yield() calls for better task management

4. Conservative Main Loop Functions

• Added 5ms timing control to WebSocketsServerCore::loop() and WebSocketsServer::loop()
• Prevents overwhelming the ESP32 network stack
• Reduces frequency of WebSocket event processing

Technical Details

• Target Platform: ESP32-specific optimizations using #if(WEBSOCKETS_NETWORK_TYPE == NETWORK_ESP32) conditionals
• Root Cause: ESP32's lwIP stack requires more careful buffer management than other platforms
• Solution: Conservative timing and proper cleanup sequences

Benefits

• Eliminates pbuf_free crashes during WebSocket disconnections
• Improves connection stability for long-running applications
• Prevents network stack overload on ESP32
• Maintains compatibility with other platforms (conditionals ensure changes only apply to ESP32)

Testing

• Successfully tested with extended soak testing (>2 hour)
• No crashes observed during rapid connection/disconnection cycles
• Improved stability for permanent WebSocket connections

This enhancement specifically addresses ESP32's unique network stack requirements while maintaining full compatibility with other Arduino platforms.