fix(server): simplify GameRoom join code

Author: xeruf

server/src/sc/server/gaming/GameRoom.java

@@ -213,23 +213,17 @@ public String getId() {
    * Join a client into this room.
    * Starts the game if full.
    *
-   * @return true if successfully joined
+   * @return true if successfully joined,
+   * false if there was no free slot
    */
-  public synchronized boolean join(Client client) throws GameRoomException {
-    for (PlayerSlot slot : this.playerSlots) {
-      // find PlayerSlot that it not in use for the new Client
-      if (slot.isEmpty() && !slot.isReserved()) {
-        fillSlot(slot, client);
-        return true;
-      }
-    }
-
-    if (this.playerSlots.size() < getMaximumPlayerCount()) {
-      fillSlot(openSlot(), client);
-      return true;
-    }
-
-    return false;
+  public synchronized boolean join(Client client) {
+    PlayerSlot slot = playerSlots.stream()
+        .filter(PlayerSlot::isFree).findFirst()
+        .orElseGet(() -> playerSlots.size() < getMaximumPlayerCount() ? openSlot() : null);
+    if(slot == null)
+      return false;
+    fillSlot(slot, client);
+    return true;
   }
 
   /**
@@ -238,7 +232,7 @@ public synchronized boolean join(Client client) throws GameRoomException {
    * @param openSlot PlayerSlot to fill
    * @param client   Client to fill PlayerSlot
    */
-  synchronized void fillSlot(PlayerSlot openSlot, Client client) throws GameRoomException {
+  synchronized void fillSlot(PlayerSlot openSlot, Client client) {
     openSlot.setClient(client); // sets role of Slot as PlayerRole
     client.send(new JoinedRoomResponse(getId()));
     startIfReady();
@@ -250,7 +244,7 @@ private boolean isReady() {
   }
 
   /** Starts game if ready and not over. */
-  private void startIfReady() throws GameRoomException {
+  private void startIfReady() {
     logger.debug("startIfReady called");
     if (isOver()) {
       logger.warn("Game already over: {}", game);

server/src/sc/server/gaming/GameRoomManager.java

@@ -142,14 +142,15 @@ public synchronized RoomWasJoinedEvent createAndJoinGame(Client client, String g
   public synchronized RoomWasJoinedEvent joinOrCreateGame(Client client, String gameType)
           throws RescuableClientException {
     for (GameRoom gameRoom : getGames()) {
+      // TODO gameType isn't checked
       if (gameRoom.join(client)) {
         return roomJoined(gameRoom);
       }
     }
     return createAndJoinGame(client, gameType);
   }
 
-  private RoomWasJoinedEvent roomJoined(GameRoom room) {
+  protected RoomWasJoinedEvent roomJoined(GameRoom room) {
     return new RoomWasJoinedEvent(room.getId(), room.getClients().size());
   }
 

server/src/sc/server/gaming/PlayerSlot.java

@@ -26,6 +26,10 @@ public GameRoom getRoom() {
     return this.room;
   }
 
+  public boolean isFree() {
+    return isEmpty() && !isReserved();
+  }
+
   public boolean isEmpty() {
     return this.client == null;
   }