Add TypingCache to maintain a list of users typing (#559)

* Add typing cache

Signed-off-by: Anant Prakash <anantprakashjsr@gmail.com>

* Add tests for typingCache

* Make test stricter

* Handle cases where expireTime is updated

* Make the slice comparisons sturdy

* Use timers to call removeUser after timeout

* Add test for TypingCache.removeUser

Signed-Off-By: Matthias Kesler <krombel@krombel.de>

* Write deterministic test
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Anant Prakash 2018-07-31 16:22:57 +05:30 committed by GitHub
parent f8ca2561cc
commit 9cdd3a66e4
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// 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 cache
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
// TypingCache maintains a list of users typing in each room.
type TypingCache struct {
sync.RWMutex
data map[string]userSet
}
// NewTypingCache returns a new TypingCache initialized for use.
func NewTypingCache() *TypingCache {
return &TypingCache{data: make(map[string]userSet)}
}
// GetTypingUsers returns the list of users typing in a room.
func (t *TypingCache) GetTypingUsers(roomID string) (users []string) {
t.RLock()
usersMap, ok := t.data[roomID]
t.RUnlock()
if ok {
users = make([]string, 0, len(usersMap))
for userID := range usersMap {
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.
func (t *TypingCache) AddTypingUser(userID, roomID string, expire *time.Time) {
expireTime := getExpireTime(expire)
if until := time.Until(expireTime); until > 0 {
timer := time.AfterFunc(until, t.timeoutCallback(userID, roomID))
t.addUser(userID, roomID, timer)
}
}
// addUser with mutex lock & replace the previous timer.
func (t *TypingCache) addUser(userID, roomID string, expiryTimer *time.Timer) {
t.Lock()
defer t.Unlock()
if t.data[roomID] == nil {
t.data[roomID] = make(userSet)
}
// Stop the timer to cancel the call to timeoutCallback
if timer, ok := t.data[roomID][userID]; ok {
// It may happen that at this stage timer fires but now we have a lock on t.
// Hence the execution of timeoutCallback will happen after we unlock.
// So we may lose a typing state, though this event is highly unlikely.
// This can be mitigated by keeping another time.Time in the map and check against it
// before removing. This however is not required in most practical scenario.
timer.Stop()
}
t.data[roomID][userID] = expiryTimer
}
// Returns a function which is called after timeout happens.
// This removes the user.
func (t *TypingCache) timeoutCallback(userID, roomID string) func() {
return func() {
t.removeUser(userID, roomID)
}
}
// removeUser with mutex lock & stop the timer.
func (t *TypingCache) removeUser(userID, roomID string) {
t.Lock()
defer t.Unlock()
if timer, ok := t.data[roomID][userID]; ok {
timer.Stop()
delete(t.data[roomID], userID)
}
}
func getExpireTime(expire *time.Time) time.Time {
if expire != nil {
return *expire
}
return time.Now().Add(defaultTypingTimeout)
}

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// 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 cache
import (
"testing"
"time"
"github.com/matrix-org/dendrite/common/test"
)
func TestTypingCache(t *testing.T) {
tCache := NewTypingCache()
if tCache == nil {
t.Fatal("NewTypingCache failed")
}
t.Run("AddTypingUser", func(t *testing.T) {
testAddTypingUser(t, tCache)
})
t.Run("GetTypingUsers", func(t *testing.T) {
testGetTypingUsers(t, tCache)
})
t.Run("removeUser", func(t *testing.T) {
testRemoveUser(t, tCache)
})
}
func testAddTypingUser(t *testing.T, tCache *TypingCache) {
present := time.Now()
tests := []struct {
userID string
roomID string
expire *time.Time
}{ // Set four users typing state to room1
{"user1", "room1", nil},
{"user2", "room1", nil},
{"user3", "room1", nil},
{"user4", "room1", nil},
//typing state with past expireTime should not take effect or removed.
{"user1", "room2", &present},
}
for _, tt := range tests {
tCache.AddTypingUser(tt.userID, tt.roomID, tt.expire)
}
}
func testGetTypingUsers(t *testing.T, tCache *TypingCache) {
tests := []struct {
roomID string
wantUsers []string
}{
{"room1", []string{"user1", "user2", "user3", "user4"}},
{"room2", []string{}},
}
for _, tt := range tests {
gotUsers := tCache.GetTypingUsers(tt.roomID)
if !test.UnsortedStringSliceEqual(gotUsers, tt.wantUsers) {
t.Errorf("TypingCache.GetTypingUsers(%s) = %v, want %v", tt.roomID, gotUsers, tt.wantUsers)
}
}
}
func testRemoveUser(t *testing.T, tCache *TypingCache) {
tests := []struct {
roomID string
userIDs []string
}{
{"room3", []string{"user1"}},
{"room4", []string{"user1", "user2", "user3"}},
}
for _, tt := range tests {
for _, userID := range tt.userIDs {
tCache.AddTypingUser(userID, tt.roomID, nil)
}
length := len(tt.userIDs)
tCache.removeUser(tt.userIDs[length-1], tt.roomID)
expLeftUsers := tt.userIDs[:length-1]
if leftUsers := tCache.GetTypingUsers(tt.roomID); !test.UnsortedStringSliceEqual(leftUsers, expLeftUsers) {
t.Errorf("Response after removal is unexpected. Want = %s, got = %s", leftUsers, expLeftUsers)
}
}
}