lockfile

type Locker interface {
	// Acquire a writer lock.
	// The default unix implementation panics if:
	// - opening the lockfile failed
	// - tried to lock a read-only lock-file
	Lock()

	// Unlock the lock.
	// The default unix implementation panics if:
	// - unlocking an unlocked lock
	// - if the lock counter is corrupted
	Unlock()

	// Acquire a reader lock.
	RLock()

	// Touch records, for others sharing the lock, that the caller was the
	// last writer.  It should only be called with the lock held.
	Touch() error

	// Modified() checks if the most recent writer was a party other than the
	// last recorded writer.  It should only be called with the lock held.
	Modified() (bool, error)

	// TouchedSince() checks if the most recent writer modified the file (likely using Touch()) after the specified time.
	TouchedSince(when time.Time) bool

	// IsReadWrite() checks if the lock file is read-write
	IsReadWrite() bool

	// AssertLocked() can be used by callers that _know_ that they hold the lock (for reading or writing), for sanity checking.
	// It might do nothing at all, or it may panic if the caller is not the owner of this lock.
	AssertLocked()

	// AssertLocked() can be used by callers that _know_ that they hold the lock locked for writing, for sanity checking.
	// It might do nothing at all, or it may panic if the caller is not the owner of this lock for writing.
	AssertLockedForWriting()
}