127 lines
2.3 KiB
Go
127 lines
2.3 KiB
Go
/**
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* Standalone signaling server for the Nextcloud Spreed app.
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* Copyright (C) 2022 struktur AG
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*
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* @author Joachim Bauch <bauch@struktur.de>
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*
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* @license GNU AGPL version 3 or any later version
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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 signaling
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import (
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"context"
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"sync"
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)
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type SingleWaiter struct {
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root bool
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ch chan struct{}
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once sync.Once
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}
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func newSingleWaiter() *SingleWaiter {
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return &SingleWaiter{
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root: true,
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ch: make(chan struct{}),
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}
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}
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func (w *SingleWaiter) subWaiter() *SingleWaiter {
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return &SingleWaiter{
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ch: w.ch,
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}
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}
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func (w *SingleWaiter) Wait(ctx context.Context) error {
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select {
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case <-w.ch:
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return nil
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case <-ctx.Done():
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return ctx.Err()
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}
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}
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func (w *SingleWaiter) cancel() {
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if !w.root {
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return
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}
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w.once.Do(func() {
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close(w.ch)
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})
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}
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type SingleNotifier struct {
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sync.Mutex
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waiter *SingleWaiter
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waiters map[*SingleWaiter]bool
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}
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func (n *SingleNotifier) NewWaiter() *SingleWaiter {
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n.Lock()
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defer n.Unlock()
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if n.waiter == nil {
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n.waiter = newSingleWaiter()
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}
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if n.waiters == nil {
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n.waiters = make(map[*SingleWaiter]bool)
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}
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w := n.waiter.subWaiter()
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n.waiters[w] = true
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return w
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}
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func (n *SingleNotifier) Reset() {
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n.Lock()
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defer n.Unlock()
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if n.waiter != nil {
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n.waiter.cancel()
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n.waiter = nil
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}
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n.waiters = nil
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}
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func (n *SingleNotifier) Release(w *SingleWaiter) {
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n.Lock()
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defer n.Unlock()
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if _, found := n.waiters[w]; found {
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delete(n.waiters, w)
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if len(n.waiters) == 0 {
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n.waiters = nil
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if n.waiter != nil {
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n.waiter.cancel()
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n.waiter = nil
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}
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}
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}
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}
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func (n *SingleNotifier) Notify() {
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n.Lock()
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defer n.Unlock()
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if n.waiter != nil {
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n.waiter.cancel()
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}
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n.waiters = nil
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}
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