mirror of
https://github.com/matrix-org/dendrite
synced 2024-08-30 15:55:20 +02:00
168 lines
4.7 KiB
Go
168 lines
4.7 KiB
Go
// Copyright 2017 Vector Creations Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package notifier
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import (
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"context"
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"runtime"
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"sync"
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"time"
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"github.com/matrix-org/dendrite/syncapi/types"
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)
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// UserDeviceStream represents a communication mechanism between the /sync request goroutine
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// and the underlying sync server goroutines.
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// Goroutines can get a UserStreamListener to wait for updates, and can Broadcast()
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// updates.
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type UserDeviceStream struct {
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UserID string
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DeviceID string
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// The lock that protects changes to this struct
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lock sync.Mutex
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// Closed when there is an update.
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signalChannel chan struct{}
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// The last sync position that there may have been an update for the user
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pos types.StreamingToken
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// The last time when we had some listeners waiting
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timeOfLastChannel time.Time
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// The number of listeners waiting
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numWaiting uint
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}
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// UserDeviceStreamListener allows a sync request to wait for updates for a user.
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type UserDeviceStreamListener struct {
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userStream *UserDeviceStream
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// Whether the stream has been closed
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hasClosed bool
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}
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// NewUserDeviceStream creates a new user stream
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func NewUserDeviceStream(userID, deviceID string, currPos types.StreamingToken) *UserDeviceStream {
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return &UserDeviceStream{
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UserID: userID,
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DeviceID: deviceID,
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timeOfLastChannel: time.Now(),
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pos: currPos,
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signalChannel: make(chan struct{}),
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}
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}
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// GetListener returns UserStreamListener that a sync request can use to wait
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// for new updates with.
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// UserStreamListener must be closed
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func (s *UserDeviceStream) GetListener(ctx context.Context) UserDeviceStreamListener {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.numWaiting++ // We decrement when UserStreamListener is closed
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listener := UserDeviceStreamListener{
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userStream: s,
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}
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// Lets be a bit paranoid here and check that Close() is being called
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runtime.SetFinalizer(&listener, func(l *UserDeviceStreamListener) {
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if !l.hasClosed {
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l.Close()
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}
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})
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return listener
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}
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// Broadcast a new sync position for this user.
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func (s *UserDeviceStream) Broadcast(pos types.StreamingToken) {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.pos = pos
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close(s.signalChannel)
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s.signalChannel = make(chan struct{})
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}
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// NumWaiting returns the number of goroutines waiting for waiting for updates.
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// Used for metrics and testing.
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func (s *UserDeviceStream) NumWaiting() uint {
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s.lock.Lock()
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defer s.lock.Unlock()
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return s.numWaiting
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}
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// TimeOfLastNonEmpty returns the last time that the number of waiting listeners
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// was non-empty, may be time.Now() if number of waiting listeners is currently
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// non-empty.
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func (s *UserDeviceStream) TimeOfLastNonEmpty() time.Time {
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s.lock.Lock()
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defer s.lock.Unlock()
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if s.numWaiting > 0 {
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return time.Now()
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}
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return s.timeOfLastChannel
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}
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func (s *UserDeviceStream) ch() <-chan struct{} {
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s.lock.Lock()
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defer s.lock.Unlock()
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return s.signalChannel
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}
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// GetSyncPosition returns last sync position which the UserStream was
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// notified about
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func (s *UserDeviceStreamListener) GetSyncPosition() types.StreamingToken {
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s.userStream.lock.Lock()
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defer s.userStream.lock.Unlock()
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return s.userStream.pos
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}
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// GetNotifyChannel returns a channel that is closed when there may be an
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// update for the user.
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// sincePos specifies from which point we want to be notified about. If there
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// has already been an update after sincePos we'll return a closed channel
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// immediately.
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func (s *UserDeviceStreamListener) GetNotifyChannel(sincePos types.StreamingToken) <-chan struct{} {
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s.userStream.lock.Lock()
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defer s.userStream.lock.Unlock()
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if s.userStream.pos.IsAfter(sincePos) {
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// If the listener is behind, i.e. missed a potential update, then we
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// want them to wake up immediately. We do this by returning a new
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// closed stream, which returns immediately when selected.
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closedChannel := make(chan struct{})
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close(closedChannel)
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return closedChannel
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}
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return s.userStream.signalChannel
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}
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// Close cleans up resources used
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func (s *UserDeviceStreamListener) Close() {
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s.userStream.lock.Lock()
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defer s.userStream.lock.Unlock()
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if !s.hasClosed {
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s.userStream.numWaiting--
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s.userStream.timeOfLastChannel = time.Now()
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}
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s.hasClosed = true
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}
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