status-go/vendor/github.com/ethereum/go-ethereum/internal/syncx/mutex.go

65 lines
1.7 KiB
Go

// Copyright 2021 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package syncx contains exotic synchronization primitives.
package syncx
// ClosableMutex is a mutex that can also be closed.
// Once closed, it can never be taken again.
type ClosableMutex struct {
ch chan struct{}
}
func NewClosableMutex() *ClosableMutex {
ch := make(chan struct{}, 1)
ch <- struct{}{}
return &ClosableMutex{ch}
}
// TryLock attempts to lock cm.
// If the mutex is closed, TryLock returns false.
func (cm *ClosableMutex) TryLock() bool {
_, ok := <-cm.ch
return ok
}
// MustLock locks cm.
// If the mutex is closed, MustLock panics.
func (cm *ClosableMutex) MustLock() {
_, ok := <-cm.ch
if !ok {
panic("mutex closed")
}
}
// Unlock unlocks cm.
func (cm *ClosableMutex) Unlock() {
select {
case cm.ch <- struct{}{}:
default:
panic("Unlock of already-unlocked ClosableMutex")
}
}
// Close locks the mutex, then closes it.
func (cm *ClosableMutex) Close() {
_, ok := <-cm.ch
if !ok {
panic("Close of already-closed ClosableMutex")
}
close(cm.ch)
}