kubernetes/pkg/registry/core/service/portallocator/operation.go

type PortAllocationOperation …

// Creates a portAllocationOperation, tracking a set of allocations & releases
// If dryRun is specified, never actually allocate or release anything
func StartOperation(pa Interface, dryRun bool) *PortAllocationOperation { … }

// Will rollback unless marked as shouldRollback = false by a Commit().  Call from a defer block
func (op *PortAllocationOperation) Finish() { … }

// (Try to) undo any operations we did
func (op *PortAllocationOperation) Rollback() []error { … }

// (Try to) perform any deferred operations.
// Note that even if this fails, we don't rollback; we always want to err on the side of over-allocation,
// and Commit should be called _after_ the owner is written
func (op *PortAllocationOperation) Commit() []error { … }

// Allocates a port, and record it for future rollback
func (op *PortAllocationOperation) Allocate(port int) error { … }

// Allocates a port, and record it for future rollback
func (op *PortAllocationOperation) AllocateNext() (int, error) { … }

// Marks a port so that it will be released if this operation Commits
func (op *PortAllocationOperation) ReleaseDeferred(port int) { … }