Lattice 0.8.7 - Folia Thread-Safety Hardening

Fixed

Critical (AsyncCatcher Errors)

• [CRITICAL] Fixed PaperTaskService.scheduleEntity() thread validation

  • Added thread ownership validation before entity access
  • Prevents unsafe entity lookups from async contexts
  • Uses ReentrantLock for better granularity

• [CRITICAL] Fixed race conditions in UI event handlers

  • Synchronized onInventoryClick() with ReentrantLock
  • Synchronized onPrepareAnvil() with ReentrantLock
  • Added closed() checks to prevent operations on closed sessions

• [CRITICAL] Fixed block/player access in text input renderers

  • Protected getBlock() calls in PaperVirtualSignTextInputRenderer.restore()
  • Protected getLocation() calls in both virtual sign and anvil renderers
  • Prevents AsyncCatcher errors during text input UI operations

• [CRITICAL] Fixed PacketEvents callback thread safety

  • Wrapped PacketEvents listeners to execute in global region scheduler
  • Prevents unsafe operations from packet thread

Important (Race Conditions)

• [IMPORTANT] Added volatile modifiers to PaperTextInputUiSession

  • completed, anvilView, signPosition, signLocation are now volatile
  • Ensures visibility across event handler and scheduler threads

• [IMPORTANT] Synchronized handleVirtualSignChange() with ReentrantLock

  • Prevents race condition with concurrent session removal

• [IMPORTANT] Synchronized PaperInventorySurfaceRenderer.render() page access

  • Copies button list atomically to avoid concurrent modification
  • Prevents IndexOutOfBoundsException

• [IMPORTANT] Synchronized runOnPlayer() ownership check

  • Prevents race condition between region ownership check and schedule

• [IMPORTANT] Added thread-safety documentation to PlaceholderAPI integrations

  • Documents that handlers are called from arbitrary threads
  • Lists unsafe and safe operations

Minor (Edge Cases)

• Improved lock granularity in session(Inventory) lookup
• Prevented double registration in registerRefreshEvent()