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