insertBorrowHandle method

int insertBorrowHandle(int sourceHandle, WASIComponentCanonicalBorrowScope scope)

Creates a canonical borrowed handle owned by scope.

The alias keeps sourceHandle live, exposes the same nominal resource and representation, and never runs the resource destructor. Dropping the alias releases both the source handle and the original borrow scope even when another task performs the drop.

Implementation

int insertBorrowHandle(
  int sourceHandle,
  WASIComponentCanonicalBorrowScope scope,
) {
  final source = _entryForHandle(sourceHandle);
  if (source == null) {
    throw StateError(
      'Unknown WASI component resource handle: $sourceHandle.',
    );
  }
  _validateScopeAccess(sourceHandle, source);
  final ambientScope = _currentScope;
  if (ambientScope?.isClosed ?? false) {
    throw StateError(
      'Cannot allocate a WASI component resource after its scope closed.',
    );
  }
  final aliasScope = ambientScope ?? source.scope;

  scope.addBorrow();
  source.borrowCount++;
  try {
    final slotIndex = _allocateSlot();
    final handle = _allocateHandle();
    final slot = _slots[slotIndex];
    slot.entry = source.borrowedAlias(
      _WASIComponentCanonicalBorrow(source, scope),
      aliasScope,
    );
    _handleToSlot[handle] = slotIndex;
    _activeCount++;
    aliasScope?._handles.add(handle);
    _recordResourceType(source.type, aliasScope);
    return handle;
  } catch (_) {
    source.borrowCount--;
    scope.releaseBorrow();
    rethrow;
  }
}