Rename the typing server to EDU server (#948)

* Blunt move and sed rename

* Rename common/ refs to typing

* Rename internal stuff in eduserver

* Rename docs and scripts

* Rename constants/filenames, goimports everything to re-order imports

6 files changed, 543 insertions, 0 deletions

diff --git a/eduserver/api/input.go b/eduserver/api/input.go
new file mode 100644
index 00000000..c95acaf1
--- /dev/null
+++ b/eduserver/api/input.go
@@ -0,0 +1,83 @@
+// 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 api provides the types that are used to communicate with the typing server.
+package api
+
+import (
+	"context"
+	"net/http"
+
+	commonHTTP "github.com/matrix-org/dendrite/common/http"
+	"github.com/matrix-org/gomatrixserverlib"
+	opentracing "github.com/opentracing/opentracing-go"
+)
+
+// InputTypingEvent is an event for notifying the typing server about typing updates.
+type InputTypingEvent struct {
+	// UserID of the user to update typing status.
+	UserID string `json:"user_id"`
+	// RoomID of the room the user is typing (or has stopped).
+	RoomID string `json:"room_id"`
+	// Typing is true if the user is typing, false if they have stopped.
+	Typing bool `json:"typing"`
+	// Timeout is the interval for which the user should be marked as typing.
+	Timeout int64 `json:"timeout"`
+	// OriginServerTS when the server received the update.
+	OriginServerTS gomatrixserverlib.Timestamp `json:"origin_server_ts"`
+}
+
+// InputTypingEventRequest is a request to EDUServerInputAPI
+type InputTypingEventRequest struct {
+	InputTypingEvent InputTypingEvent `json:"input_typing_event"`
+}
+
+// InputTypingEventResponse is a response to InputTypingEvents
+type InputTypingEventResponse struct{}
+
+// EDUServerInputAPI is used to write events to the typing server.
+type EDUServerInputAPI interface {
+	InputTypingEvent(
+		ctx context.Context,
+		request *InputTypingEventRequest,
+		response *InputTypingEventResponse,
+	) error
+}
+
+// EDUServerInputTypingEventPath is the HTTP path for the InputTypingEvent API.
+const EDUServerInputTypingEventPath = "/api/eduserver/input"
+
+// NewEDUServerInputAPIHTTP creates a EDUServerInputAPI implemented by talking to a HTTP POST API.
+func NewEDUServerInputAPIHTTP(eduServerURL string, httpClient *http.Client) EDUServerInputAPI {
+	if httpClient == nil {
+		httpClient = http.DefaultClient
+	}
+	return &httpEDUServerInputAPI{eduServerURL, httpClient}
+}
+
+type httpEDUServerInputAPI struct {
+	eduServerURL string
+	httpClient   *http.Client
+}
+
+// InputRoomEvents implements EDUServerInputAPI
+func (h *httpEDUServerInputAPI) InputTypingEvent(
+	ctx context.Context,
+	request *InputTypingEventRequest,
+	response *InputTypingEventResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "InputTypingEvent")
+	defer span.Finish()
+
+	apiURL := h.eduServerURL + EDUServerInputTypingEventPath
+	return commonHTTP.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
diff --git a/eduserver/api/output.go b/eduserver/api/output.go
new file mode 100644
index 00000000..8696acf4
--- /dev/null
+++ b/eduserver/api/output.go
@@ -0,0 +1,34 @@
+// 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 api
+
+import "time"
+
+// OutputTypingEvent is an entry in typing server output kafka log.
+// This contains the event with extra fields used to create 'm.typing' event
+// in clientapi & federation.
+type OutputTypingEvent struct {
+	// The Event for the typing edu event.
+	Event TypingEvent `json:"event"`
+	// ExpireTime is the interval after which the user should no longer be
+	// considered typing. Only available if Event.Typing is true.
+	ExpireTime *time.Time
+}
+
+// TypingEvent represents a matrix edu event of type 'm.typing'.
+type TypingEvent struct {
+	Type   string `json:"type"`
+	RoomID string `json:"room_id"`
+	UserID string `json:"user_id"`
+	Typing bool   `json:"typing"`
+}
diff --git a/eduserver/cache/cache.go b/eduserver/cache/cache.go
new file mode 100644
index 00000000..46f7a2b1
--- /dev/null
+++ b/eduserver/cache/cache.go
@@ -0,0 +1,180 @@
+// 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
+
+// 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),
+	}
+}
+
+// New returns a new EDUCache initialised for use.
+func New() *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)
+}
diff --git a/eduserver/cache/cache_test.go b/eduserver/cache/cache_test.go
new file mode 100644
index 00000000..8a1b6f79
--- /dev/null
+++ b/eduserver/cache/cache_test.go
@@ -0,0 +1,99 @@
+// 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 TestEDUCache(t *testing.T) {
+	tCache := New()
+	if tCache == nil {
+		t.Fatal("New 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 *EDUCache) { // nolint: unparam
+	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 *EDUCache) {
+	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 *EDUCache) {
+	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)
+		}
+	}
+}
diff --git a/eduserver/eduserver.go b/eduserver/eduserver.go
new file mode 100644
index 00000000..8ddd2c52
--- /dev/null
+++ b/eduserver/eduserver.go
@@ -0,0 +1,40 @@
+// 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 eduserver
+
+import (
+	"net/http"
+
+	"github.com/matrix-org/dendrite/common/basecomponent"
+	"github.com/matrix-org/dendrite/eduserver/api"
+	"github.com/matrix-org/dendrite/eduserver/cache"
+	"github.com/matrix-org/dendrite/eduserver/input"
+)
+
+// SetupEDUServerComponent sets up and registers HTTP handlers for the
+// EDUServer component. Returns instances of the various roomserver APIs,
+// allowing other components running in the same process to hit the query the
+// APIs directly instead of having to use HTTP.
+func SetupEDUServerComponent(
+	base *basecomponent.BaseDendrite,
+	eduCache *cache.EDUCache,
+) api.EDUServerInputAPI {
+	inputAPI := &input.EDUServerInputAPI{
+		Cache:                  eduCache,
+		Producer:               base.KafkaProducer,
+		OutputTypingEventTopic: string(base.Cfg.Kafka.Topics.OutputTypingEvent),
+	}
+
+	inputAPI.SetupHTTP(http.DefaultServeMux)
+	return inputAPI
+}
diff --git a/eduserver/input/input.go b/eduserver/input/input.go
new file mode 100644
index 00000000..e0cc6922
--- /dev/null
+++ b/eduserver/input/input.go
@@ -0,0 +1,107 @@
+// 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 input
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"time"
+
+	"github.com/matrix-org/dendrite/common"
+	"github.com/matrix-org/dendrite/eduserver/api"
+	"github.com/matrix-org/dendrite/eduserver/cache"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+	"gopkg.in/Shopify/sarama.v1"
+)
+
+// EDUServerInputAPI implements api.EDUServerInputAPI
+type EDUServerInputAPI struct {
+	// Cache to store the current typing members in each room.
+	Cache *cache.EDUCache
+	// The kafka topic to output new typing events to.
+	OutputTypingEventTopic string
+	// kafka producer
+	Producer sarama.SyncProducer
+}
+
+// InputTypingEvent implements api.EDUServerInputAPI
+func (t *EDUServerInputAPI) InputTypingEvent(
+	ctx context.Context,
+	request *api.InputTypingEventRequest,
+	response *api.InputTypingEventResponse,
+) error {
+	ite := &request.InputTypingEvent
+	if ite.Typing {
+		// user is typing, update our current state of users typing.
+		expireTime := ite.OriginServerTS.Time().Add(
+			time.Duration(ite.Timeout) * time.Millisecond,
+		)
+		t.Cache.AddTypingUser(ite.UserID, ite.RoomID, &expireTime)
+	} else {
+		t.Cache.RemoveUser(ite.UserID, ite.RoomID)
+	}
+
+	return t.sendEvent(ite)
+}
+
+func (t *EDUServerInputAPI) sendEvent(ite *api.InputTypingEvent) error {
+	ev := &api.TypingEvent{
+		Type:   gomatrixserverlib.MTyping,
+		RoomID: ite.RoomID,
+		UserID: ite.UserID,
+		Typing: ite.Typing,
+	}
+	ote := &api.OutputTypingEvent{
+		Event: *ev,
+	}
+
+	if ev.Typing {
+		expireTime := ite.OriginServerTS.Time().Add(
+			time.Duration(ite.Timeout) * time.Millisecond,
+		)
+		ote.ExpireTime = &expireTime
+	}
+
+	eventJSON, err := json.Marshal(ote)
+	if err != nil {
+		return err
+	}
+
+	m := &sarama.ProducerMessage{
+		Topic: string(t.OutputTypingEventTopic),
+		Key:   sarama.StringEncoder(ite.RoomID),
+		Value: sarama.ByteEncoder(eventJSON),
+	}
+
+	_, _, err = t.Producer.SendMessage(m)
+	return err
+}
+
+// SetupHTTP adds the EDUServerInputAPI handlers to the http.ServeMux.
+func (t *EDUServerInputAPI) SetupHTTP(servMux *http.ServeMux) {
+	servMux.Handle(api.EDUServerInputTypingEventPath,
+		common.MakeInternalAPI("inputTypingEvents", func(req *http.Request) util.JSONResponse {
+			var request api.InputTypingEventRequest
+			var response api.InputTypingEventResponse
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := t.InputTypingEvent(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+}