49 lines
1.6 KiB
Go
49 lines
1.6 KiB
Go
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// Copyright (C) 2022 The pages authors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero 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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// This program 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 Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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package lock
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import (
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"context"
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)
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// New creates a Lock and populates its channel. Once constructed, callers can use the Lock(ctx) method to lock a
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// portion of code. Unlike the sync.Mutex implementation, this allows a Lock operation to be deadlined or cancelled
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// using the provided context.
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func New() Lock {
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lock := Lock{ch: make(chan bool, 1)}
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lock.ch <- true
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return lock
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}
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// Lock encapsulates the channel used to provide locking and unlocking capabilities. We don't want this channel
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// exposed as someone may interact with it in malicious ways.
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type Lock struct {
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ch chan bool
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}
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// Lock attempts to obtain the lock given the provided context. This call can be time-bound using the
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// context.WithDeadline method call to decorate the context with a halting point.
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func (l Lock) Lock(ctx context.Context) (unlock func(), err error) {
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case v := <-l.ch:
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return func() { l.ch <- v }, nil
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}
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}
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