// subscribe subscribes to the topic for this game
// Returns a channel of Messages that can be used to receive messages
// Make sure to send it a new redis.Conn. It will handle closing it
// when finished.
func subscribe(ctx context.Context, con redis.Conn, g *Game) (<-chan *message, error) {
lc := "Subscribe"
c := make(chan *message)
psc := redis.PubSubConn{con}
logger.Info(ctx, lc, "Subscribing to topic '%v'", g.ID)
err := psc.Subscribe(g.ID)
if err != nil {
logger.Info(ctx, lc, "Error Subscribing. %v", err)
close(c)
return c, err
}
go func(c chan<- *message) {
defer con.Close()
defer close(c)
for {
switch v := psc.Receive().(type) {
case redis.Message:
msg := new(message)
err := msg.unmarshalGob(v.Data)
if err != nil {
logger.Error(ctx, lc, "Could not decode message. Closing channel. %v, %v", v, err)
return
}
logger.Info(ctx, lc, "Received Message. Sending %#v to channel.", msg)
c <- msg
// special case for LostMessage, since we know to close at this point.
if msg.Type == lostMessage {
logger.Info(ctx, lc, "Lost Message, Closing Subscribe Pipeline.")
return
}
case error:
logger.Error(ctx, lc, "Error processing messages. Closing channel. %v", err)
return
default:
logger.Info(ctx, lc, "Received unknown message. Ignored: %#v", v)
}
}
}(c)
return c, nil
}
// findGame finds a game in the list of open games. If one doesn't exist, creates a new gameid
// returns a new Game and if it's a new game or not.
func findGame(ctx context.Context, con redis.Conn) (*Game, bool, error) {
lc := "FindGame"
// do we have an open game?
gameID, err := redis.String(con.Do("RPOP", openGames))
// ignore nil errors, since that is expected
if err != nil && err != redis.ErrNil {
logger.Error(ctx, lc, "Error finding open game: %v", err)
return new(Game), false, err
}
// is this a brand new game?
isNew := (gameID == "")
if isNew {
logger.Info(ctx, lc, "Could not find open game, creating one... ")
u, err := uuid.NewV4()
if err != nil {
return nil, false, err
}
gameID = u.String()
}
return NewGame(gameID), isNew, nil
}
// ensureSubscribers Make sure n number of Game subscriptions at this point.
// Blocks until we have two people. Times out on too many retries.
func ensureSubscribers(ctx context.Context, con redis.Conn, g *Game, n int) error {
lc := "EnsureSubscribers"
for i := 0; i <= 5; i++ {
res, err := con.Do("PUBSUB", "NUMSUB", g.ID)
if err != nil {
logger.Error(ctx, lc, "Error getting number of subscriptions: %v", err)
return err
}
vals, err := redis.Values(res, err)
if err != nil {
logger.Error(ctx, lc, "Error converting to values: %v", err)
return err
}
if l := len(vals); l != 2 {
err := fmt.Errorf("Should only be two items in the result. Weird. %#v. %v.", vals, l)
logger.Error(ctx, lc, err.Error())
return err
}
count, ok := vals[1].(int64)
if !ok {
val := vals[1]
err := fmt.Errorf("Second value should be an integer. %T %#v", val, val)
logger.Error(ctx, lc, err.Error())
return err
}
logger.Info(ctx, lc, "Found %v subscriptions for Game. Require %v", count, n)
if int(count) == n {
return nil
}
logger.Info(ctx, lc, "Could not find enough subscriptions, retrying...")
time.Sleep(100 * time.Millisecond)
}
err := errors.New("Timeout attempting to ensure subscriber count of " + strconv.Itoa(n))
logger.Error(ctx, lc, err.Error())
return err
}
// beginHandler Streams BEGIN to client once we are good to go.
func beginHandler(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer, msg *message) error {
lc := "beginHandler"
ctx := stream.Context()
res := &Response{Event: &Response_Turn{Turn: Response_BEGIN}}
err := sendResponse(stream, res)
if err != nil {
logger.Error(ctx, lc, "Error sending BEGIN event. %v", err)
return err
}
// if not the player that BEGAN (so first player to join), then START your turn
if msg.Player == player.Id {
logger.Info(ctx, lc, "Publishing end turn %v", stopTurnMessage)
return publish(ctx, con, game, message{Player: player.Id, Type: stopTurnMessage, Data: msg.Data})
}
logger.Info(ctx, lc, "Not doing anything with Begin. It's not my job.")
return nil
}
// sendResponse Sends a request.
func sendResponse(stream SimonSays_GameServer, r *Response) error {
lc := "Response"
ctx := stream.Context()
logger.Info(ctx, lc, "Sending response: %v", r)
err := stream.Send(r)
if err != nil {
logger.Error(ctx, lc, "Error sending: %v", err)
}
return err
}
// handle Processing pub/sub events and does things with them
// Think "controller".
func handle(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer, msg *message) error {
lc := "Handler"
ctx := stream.Context()
logger.Info(ctx, lc, "Handling Message: %#v", msg)
fn, ok := handlers[msg.Type]
if !ok {
logger.Error(ctx, lc, "Could not find a handler for this event. %#v", msg)
return handlerNotFoundError("msg.Type")
}
return fn(con, game, player, stream, msg)
}
// sendLightupEvent sends out a lightup event to everyone.
func sendLightupEvent(press *Request_Press, stream SimonSays_GameServer, con redis.Conn, game *Game) error {
buf := new(bytes.Buffer)
err := gob.NewEncoder(buf).Encode(press.Press)
ctx := stream.Context()
if err != nil {
logger.Info(ctx, "sendLightupEvent", "Error gob encoding Color. %v, %v", press.Press, err)
return err
}
// send out lightup events.
return publish(ctx, con, game, message{Type: lightUpMessage, Data: buf.Bytes()})
}
// handleColorPress handles one color being pressed.
// If it's the player turn it modifies the given game and sends a lightUpMessage to Redis.
// This function is thread safe.
func handleColorPress(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer) (bool, error) {
lc := "handleColorPress"
ctx := stream.Context()
press, err := receivePressRequest(stream)
if err != nil {
logger.Error(ctx, lc, "Press Error. Sending to err channel, and shutting down %v", err)
return true, err
}
logger.Info(ctx, lc, "Press Received: %v", press)
//lock the game for this entire block, since we are doing lots of things with
//it, and this will prevent any concurrency issues.
game.mu.Lock()
defer game.mu.Unlock()
// only accept input when it is my turn!
if !game.isMyTurn() {
logger.Info(ctx, lc, "Not my turn. Ignored press.")
return false, nil
}
err = game.pressColor(press.Press)
if err == ErrColorPressedOutOfTurn {
logger.Info(ctx, lc, "Colour pressed out of turn. Ignored.")
} else if err != nil {
return true, err
}
err = sendLightupEvent(press, stream, con, game)
if err != nil {
return true, err
}
// When you reach the point that the game has turned.
return handleEndOfTurn(stream, con, game, player)
}
// receiveRequest receives a request.
func receiveRequest(stream SimonSays_GameServer) (*Request, error) {
lc := "Request"
ctx := stream.Context()
req, err := stream.Recv()
if err != nil {
logger.Error(ctx, lc, "Error recieving: %v", err)
return nil, err
}
logger.Info(ctx, lc, "Received: %v", req)
return req, nil
}
// lightUpHandler handles LIGHTUP events, letting everyone know to lightup
// their colours.
func lightUpHandler(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer, msg *message) error {
lc := "lightUpHandler"
ctx := stream.Context()
c := new(Color)
buf := bytes.NewBuffer(msg.Data)
err := gob.NewDecoder(buf).Decode(c)
if err != nil {
logger.Error(ctx, lc, "Could not convert colour. %#v. %v", msg, err)
return err
}
logger.Info(ctx, lc, "Sending stream response to Light Up %v", c)
return sendResponse(stream, &Response{Event: &Response_Lightup{Lightup: *c}})
}
// publish publishes a message to the game's topic.
func publish(ctx context.Context, con redis.Conn, g *Game, msg message) error {
lc := "Publish"
logger.Info(ctx, lc, "Sending message: %#v, to topic: '%v'", msg, g.ID)
data, err := msg.marshalGob()
if err != nil {
logger.Error(ctx, lc, "Error encoding message. %#v, %v", msg, err)
return err
}
_, err = con.Do("PUBLISH", g.ID, data)
if err != nil {
logger.Error(ctx, lc, "Error publishing message. %#v, %v", msg, err)
}
return err
}
// what happens when the game is lost. Returns io.EOF to show that the game should be shut down.
func lostHandler(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer, msg *message) error {
lc := "lostHandler"
ctx := stream.Context()
logger.Info(ctx, lc, "Received Lost Event: %#v", msg)
var err error
// if I lost...
turn := Response_WIN
if msg.Player == player.Id {
turn = Response_LOSE
}
err = sendResponse(stream, &Response{Event: &Response_Turn{Turn: turn}})
if err != nil {
return err
}
return io.EOF
}
// recvPress Manages receiving Press Events through a go-routine.
// Will need it's own Redis connection, that it will close once complete.
// Sends io.EOF when the connection closes, and pushes the error into the chan if it
// occurs.
func recvPress(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer) <-chan error {
lc := "RecvPress"
ctx := stream.Context()
c := make(chan error, 10)
logger.Info(ctx, lc, "Start recieving Press events...")
go func() {
defer close(c)
defer con.Close()
for {
stop, err := handleColorPress(con, game, player, stream)
if err != nil {
c <- err
return
} else if stop {
return
}
}
}()
return c
}
// stopTurnHandler My turn has finished, so, tell the other player
// to START_TURN, and me to END_TURN.
func stopTurnHandler(con redis.Conn, game *Game, player *Request_Player, stream SimonSays_GameServer, msg *message) error {
lc := "stopTurnHandler"
ctx := stream.Context()
// if I'm the player that sent out the message, let the client know
if player.Id == msg.Player {
return sendResponse(stream, &Response{Event: &Response_Turn{Turn: Response_STOP_TURN}})
}
// otherwise, it's time for the other player to start
buf := bytes.NewBuffer(msg.Data)
c := []Color{}
err := gob.NewDecoder(buf).Decode(&c)
if err != nil {
logger.Error(ctx, lc, "Error decoding message colors. %#v. %v", msg, err)
return err
}
logger.Info(ctx, lc, "Starting turn with colors: %v", c)
game.StartTurn(c)
return sendResponse(stream, &Response{Event: &Response_Turn{Turn: Response_START_TURN}})
}
// handleEndOfTurn handles if it is the end of the turn, and if the player has lost (bool).
func handleEndOfTurn(stream SimonSays_GameServer, con redis.Conn, game *Game, player *Request_Player) (bool, error) {
lc := "handleEndOfTurn"
ctx := stream.Context()
// if not my turn, exit early.
if game.isMyTurn() {
return false, nil
}
if game.match() {
b, err := game.encodePresses()
if err != nil {
logger.Error(ctx, lc, "Error encoding presses: %#v, %v", game, err)
return false, err
}
msg := message{Type: stopTurnMessage, Player: player.Id, Data: b}
if err := publish(ctx, con, game, msg); err != nil {
logger.Error(ctx, lc, "error publishing StopTurnMessage %#v, %v", msg, err)
return false, err
}
return false, nil
}
// if there is no match, you did something wrong. otherwise, my friend, you have lost the game.
msg := message{Type: lostMessage, Player: player.Id}
if err := publish(ctx, con, game, msg); err != nil {
logger.Error(ctx, lc, "error publishing LostMessage %#v, %v", msg, err)
return false, err
}
// and we are done taking input - end of game!
logger.Info(ctx, lc, "We are done taking input. Returning that we have lost. %#v", game)
return true, nil
}
// closeOpenGame make sure the open game is removed
// from the open game list.
func closeOpenGame(ctx context.Context, con redis.Conn, g *Game) error {
logger.Info(ctx, "CloseOpenGame", "Removing open game %v", g.ID)
_, err := con.Do("LREM", openGames, 1, g.ID)
return err
}
// addOpenGame Adds an open game to the list.
func addOpenGame(ctx context.Context, con redis.Conn, g *Game) error {
logger.Info(ctx, "AddOpenGame", "Adding open game %v", g.ID)
_, err := con.Do("LPUSH", openGames, g.ID)
return err
}
// Game function is an implementation of the gRPC Game Service.
// When connected, this is the main functionality of running a
// Game for the connected player.
func (s *SimonSays) Game(stream SimonSays_GameServer) error {
ctx := stream.Context()
defer logger.Clear(ctx)
lc := "Game"
// first let's get the player
req, err := receiveRequest(stream)
if err != nil {
return err
}
player := req.GetJoin()
if player == nil {
logger.Error(ctx, lc, "Player was nil on initial join request. %v", req)
return errors.New("Player was nil on initial join request.")
}
logger.Set(ctx, "Player", player.Id)
logger.Info(ctx, lc, "Player %#v is attempting to join.", player)
// find what game to join
con := s.pool.Get()
defer con.Close()
game, isNew, err := findGame(ctx, con)
if err != nil {
return err
}
logger.Set(ctx, "Game", game.ID)
logger.Info(ctx, lc, "Connecting to game %v. New?: %v", game.ID, isNew)
logger.Info(ctx, lc, "Start to receive PubSub messages")
// make sure that you always unjoin, if something happens to go wrong.
defer func() {
con := s.pool.Get()
err := closeOpenGame(ctx, con, game)
if err != nil {
logger.Error(ctx, lc, "Error attempting to close game. %v", err)
}
err = con.Close()
if err != nil {
logger.Error(ctx, lc, "Error closing close open game connection. %v", err)
}
}()
// make sure that at the end, you always unsubscribe.
defer func() {
con := s.pool.Get()
err := redis.PubSubConn{con}.Unsubscribe(game.ID)
if err != nil {
logger.Error(ctx, lc, "Error unsubscribing from Game Topic %v, %v", game.ID, err)
}
err = con.Close()
if err != nil {
logger.Error(ctx, lc, "Error closing unsubscribe connection. %v", err)
}
}()
msgs, err := subscribe(ctx, s.pool.Get(), game)
if err != nil {
return err
}
if err := connectGame(ctx, con, game, player, isNew); err != nil {
return err
}
// subscribe to incoming key events, and get back a channel of errors.
perrs := recvPress(s.pool.Get(), game, player, stream)
for {
select {
// process incoming messages from RedisPubSub, and send messages.
case msg := <-msgs:
if msg == nil {
logger.Error(ctx, lc, "Message Channel has closed. Exiting.")
return nil
}
logger.Info(ctx, lc, "Handling incoming messsage...")
err := handle(con, game, player, stream, msg)
if err != nil {
// if we are EOF, then simply exit.
if err == io.EOF {
logger.Info(ctx, lc, "[Game] EOF. Closing connection.")
return nil
}
return err
}
// check to see if there are any issues with press errors.
case err := <-perrs:
// remember, a closed channel, will return a nil err.
if err != nil {
logger.Error(ctx, lc, "There was a press error. %v", err)
return err
}
}
}
}