semaphore

Documentation

Index

• func Unlink(name string) error
• type Semaphore
  • func Open(name string, excl bool, perm os.FileMode, val int) (Semaphore, error)

Functions

func Unlink

func Unlink(name string) error

Unlink removes the named semaphore referred to by name. The semaphore name is removed immediately. The semaphore is destroyed once all other processes that have the semaphore open close it.

Types

type Semaphore

type Semaphore interface {

	// Name returns the name of the semaphore.
	Name() string

	// Close closes the semaphore.
	Close() error

	// Signal increments (unlocks) the semaphore pointed to by sem.  If
	// the semaphore's value consequently becomes greater than zero, then
	// another process or thread blocked in a Wait() call will be woken
	// up and proceed to lock the semaphore.
	Signal() error

	// Wait decrements (locks) the semaphore pointed to by sem.  If
	// the semaphore's value is greater than zero, then the decrement
	// proceeds, and the function returns, immediately.  If the semaphore
	// currently has the value zero, then the call blocks until either it
	// becomes possible to perform the decrement (i.e., the semaphore value
	// ises above zero), or a signal handler interrupts the call.
	Wait() error

	// TryWait is the same as Wait(), except that if the decrement
	// cannot be immediately performed, then call returns a true flag and
	// no error.
	TryWait() (bool, error)

	// TimedWait is the same as Wait(), except that abs_timeout
	// specifies a limit on the amount of time that the call should block if
	// the decrement cannot be immediately performed.
	TimedWait(timeout time.Duration) error

	// Value returns the current value of the semaphore. If one or more
	// processes or threads are blocked waiting to lock the
	// semaphore with Wait(), POSIX.1 permits two possibilities for the
	// value returned in sval: either 0 is returned; or a negative number
	// whose absolute value is the count of the number of processes and
	// threads currently blocked in Wait().  Linux adopts the former
	// behavior.
	Value() (int, error)
}

Semaphore enables processes and threads to synchronize their actions.

func Open

func Open(
	name string, excl bool, perm os.FileMode, val int) (Semaphore, error)

Open creates a new, named semaphore or opens an existing one if one exists with the given name.