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// Copyright 2017 Vector Creations Ltd
// Copyright 2017-2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package caching
import (
"sync"
"time"
)
const defaultTypingTimeout = 10 * time.Second
// userSet is a map of user IDs to a timer, timer fires at expiry.
type userSet map[string]*time.Timer
// TimeoutCallbackFn is a function called right after the removal of a user
// from the typing user list due to timeout.
// latestSyncPosition is the typing sync position after the removal.
type TimeoutCallbackFn func(userID, roomID string, latestSyncPosition int64)
type roomData struct {
syncPosition int64
userSet userSet
}
// EDUCache maintains a list of users typing in each room.
type EDUCache struct {
sync.RWMutex
latestSyncPosition int64
data map[string]*roomData
timeoutCallback TimeoutCallbackFn
}
// Create a roomData with its sync position set to the latest sync position.
// Must only be called after locking the cache.
func (t *EDUCache) newRoomData() *roomData {
return &roomData{
syncPosition: t.latestSyncPosition,
userSet: make(userSet),
}
}
// NewTypingCache returns a new EDUCache initialised for use.
func NewTypingCache() *EDUCache {
return &EDUCache{data: make(map[string]*roomData)}
}
// SetTimeoutCallback sets a callback function that is called right after
// a user is removed from the typing user list due to timeout.
func (t *EDUCache) SetTimeoutCallback(fn TimeoutCallbackFn) {
t.timeoutCallback = fn
}
// GetTypingUsers returns the list of users typing in a room.
func (t *EDUCache) GetTypingUsers(roomID string) []string {
users, _ := t.GetTypingUsersIfUpdatedAfter(roomID, 0)
// 0 should work above because the first position used will be 1.
return users
}
// GetTypingUsersIfUpdatedAfter returns all users typing in this room with
// updated == true if the typing sync position of the room is after the given
// position. Otherwise, returns an empty slice with updated == false.
func (t *EDUCache) GetTypingUsersIfUpdatedAfter(
roomID string, position int64,
) (users []string, updated bool) {
t.RLock()
defer t.RUnlock()
roomData, ok := t.data[roomID]
if ok && roomData.syncPosition > position {
updated = true
userSet := roomData.userSet
users = make([]string, 0, len(userSet))
for userID := range userSet {
users = append(users, userID)
}
}
return
}
// AddTypingUser sets an user as typing in a room.
// expire is the time when the user typing should time out.
// if expire is nil, defaultTypingTimeout is assumed.
// Returns the latest sync position for typing after update.
func (t *EDUCache) AddTypingUser(
userID, roomID string, expire *time.Time,
) int64 {
expireTime := getExpireTime(expire)
if until := time.Until(expireTime); until > 0 {
timer := time.AfterFunc(until, func() {
latestSyncPosition := t.RemoveUser(userID, roomID)
if t.timeoutCallback != nil {
t.timeoutCallback(userID, roomID, latestSyncPosition)
}
})
return t.addUser(userID, roomID, timer)
}
return t.GetLatestSyncPosition()
}
// addUser with mutex lock & replace the previous timer.
// Returns the latest typing sync position after update.
func (t *EDUCache) addUser(
userID, roomID string, expiryTimer *time.Timer,
) int64 {
t.Lock()
defer t.Unlock()
t.latestSyncPosition++
if t.data[roomID] == nil {
t.data[roomID] = t.newRoomData()
} else {
t.data[roomID].syncPosition = t.latestSyncPosition
}
// Stop the timer to cancel the call to timeoutCallback
if timer, ok := t.data[roomID].userSet[userID]; ok {
// It may happen that at this stage the timer fires, but we now have a lock on
// it. Hence the execution of timeoutCallback will happen after we unlock. So
// we may lose a typing state, though this is highly unlikely. This can be
// mitigated by keeping another time.Time in the map and checking against it
// before removing, but its occurrence is so infrequent it does not seem
// worthwhile.
timer.Stop()
}
t.data[roomID].userSet[userID] = expiryTimer
return t.latestSyncPosition
}
// RemoveUser with mutex lock & stop the timer.
// Returns the latest sync position for typing after update.
func (t *EDUCache) RemoveUser(userID, roomID string) int64 {
t.Lock()
defer t.Unlock()
roomData, ok := t.data[roomID]
if !ok {
return t.latestSyncPosition
}
timer, ok := roomData.userSet[userID]
if !ok {
return t.latestSyncPosition
}
timer.Stop()
delete(roomData.userSet, userID)
t.latestSyncPosition++
t.data[roomID].syncPosition = t.latestSyncPosition
return t.latestSyncPosition
}
func (t *EDUCache) GetLatestSyncPosition() int64 {
t.Lock()
defer t.Unlock()
return t.latestSyncPosition
}
func getExpireTime(expire *time.Time) time.Time {
if expire != nil {
return *expire
}
return time.Now().Add(defaultTypingTimeout)
}
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