mirror of
https://github.com/ProtonMail/proton-bridge.git
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51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
// Copyright (c) 2020 Proton Technologies AG
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//
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// This file is part of ProtonMail Bridge.
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//
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// ProtonMail Bridge is free software: you can redistribute it and/or modify
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// it under the terms of the GNU 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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// ProtonMail Bridge 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 General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with ProtonMail Bridge. If not, see <https://www.gnu.org/licenses/>.
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package updater
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import (
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"sync/atomic"
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"github.com/pkg/errors"
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)
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var ErrOperationOngoing = errors.New("the operation is already ongoing")
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// locker is an easy way to ensure we only perform one update at a time.
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type locker struct {
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ongoing atomic.Value
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}
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func newLocker() *locker {
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l := &locker{}
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l.ongoing.Store(false)
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return l
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}
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func (l *locker) doOnce(fn func() error) error {
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if l.ongoing.Load().(bool) {
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return ErrOperationOngoing
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}
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l.ongoing.Store(true)
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defer func() { l.ongoing.Store(false) }()
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return fn()
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}
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