Fantom-foundation/go-lachesis

package utils

import (
    "runtime"
    "sync/atomic"
)

// SpinLock implements a simple atomic spin lock, the zero value for a SpinLock is an unlocked spinlock.
type SpinLock struct {
    f uint32
}

// Lock locks sl. If the lock is already in use, the caller blocks until Unlock is called
func (sl *SpinLock) Lock() {
    for !sl.TryLock() {
        runtime.Gosched() // allow other goroutines to do work.
    }
}

// Unlock unlocks sl, unlike [Mutex.Unlock](http://golang.org/pkg/sync/#Mutex.Unlock),
// there's no harm calling it on an unlocked SpinLock
func (sl *SpinLock) Unlock() {
    atomic.StoreUint32(&sl.f, 0)
}

// TryLock will try to lock sl and return whether it succeed or not without blocking.
func (sl *SpinLock) TryLock() bool {
    return atomic.CompareAndSwapUint32(&sl.f, 0, 1)
}

// String is human readable lock state
func (sl *SpinLock) String() string {
    if atomic.LoadUint32(&sl.f) == 1 {
        return "Locked"
    }
    return "Unlocked"
}