only allow a feed to have one connection open

hawkular · Jul 14, 2015 · 6389c32 · 6389c32
1 parent c5b23e5
commit 6389c32
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Showing 3 changed files with 46 additions and 12 deletions.
diff --git a/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/ConnectedFeeds.java b/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/ConnectedFeeds.java
@@ -26,6 +26,7 @@
 import javax.ejb.LockType;
 import javax.ejb.Singleton;
 import javax.ejb.Startup;
+import javax.websocket.CloseReason;
 import javax.websocket.Session;
 
 /**
@@ -57,18 +58,43 @@ public Session getSession(String feedId) {
     }
 
     @Lock(LockType.WRITE)
-    public void addSession(String feedId, Session feedSession) {
-        // TODO what happens if a feed already has a session open?
-        this.sessions.put(feedId, feedSession);
-        MsgLogger.LOG.infof("A feed session has been added [%s]. There are now [%d] connected feeds",
-                feedId, this.sessions.size());
+    public void addSession(String feedId, Session newSession) {
+        Session oldSession = this.sessions.putIfAbsent(feedId, newSession);
+        if (oldSession == null) {
+            MsgLogger.LOG.infof("A feed session has been added [%s]. There are now [%d] connected feeds",
+                    feedId, this.sessions.size());
+        } else {
+            // a feed already had a session open, cannot open more than one
+            try {
+                MsgLogger.LOG.errorClosingExtraFeedSession(feedId);
+                newSession.close(new CloseReason(CloseReason.CloseCodes.VIOLATED_POLICY,
+                        "Cannot have multiple sessions open, the new one will be closed"));
+            } catch (Exception e) {
+                MsgLogger.LOG.errorCannotCloseExtraFeedSession(feedId, e);
+            }
+        }
     }
 
     @Lock(LockType.WRITE)
-    public void removeSession(String feedId) {
-        this.sessions.remove(feedId);
-        MsgLogger.LOG.infof("A feed session has been removed [%s]. There are now [%d] connected feeds",
-                feedId, this.sessions.size());
+    public void removeSession(String feedId, Session doomedSession) {
+        boolean removed = false;
+
+        // If no session was passed in, remove any session associated with the given feed.
+        // If a session was passed in, only remove it if the feedId is associated with that session.
+        // This is to support the need to close extra sessions a feed might have created.
+        if (doomedSession == null) {
+            removed = this.sessions.remove(feedId) != null;
+        } else {
+            Session existingSession = this.sessions.get(feedId);
+            if (existingSession != null && existingSession.getId().equals(doomedSession.getId())) {
+                removed = this.sessions.remove(feedId) != null;
+            }
+        }
+
+        if (removed) {
+            MsgLogger.LOG.infof("A feed session has been removed [%s]. There are now [%d] connected feeds",
+                    feedId, this.sessions.size());
+        }
     }
 
 }
diff --git a/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/FeedCommWebSocket.java b/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/FeedCommWebSocket.java
@@ -48,7 +48,7 @@ public class FeedCommWebSocket {
 
     @OnOpen
     public void feedSessionOpen(Session session, @PathParam("feedId") String feedId) {
-        MsgLogger.LOG.infof("Feed [%s] connected", feedId);
+        MsgLogger.LOG.infof("Feed [%s] session opened", feedId);
         connectedFeeds.addSession(feedId, session);
     }
 
@@ -89,7 +89,7 @@ public String feedMessage(String commandAndJsonStr, Session session, @PathParam(
 
     @OnClose
     public void feedSessionClose(Session session, CloseReason reason, @PathParam("feedId") String feedId) {
-        MsgLogger.LOG.infof("Feed [%s] closed session. Reason=[%s]", feedId, reason);
-        connectedFeeds.removeSession(feedId);
+        MsgLogger.LOG.infof("Feed [%s] session closed. Reason=[%s]", feedId, reason);
+        connectedFeeds.removeSession(feedId, session);
     }
 }
diff --git a/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/MsgLogger.java b/modules/feed-comm/src/main/java/org/hawkular/feedcomm/ws/MsgLogger.java
@@ -38,4 +38,12 @@ public interface MsgLogger extends BasicLogger {
     @Message(id = 2, value = "Failed to execute command [%s] with json [%s] for feed [%s]")
     void errorCommandExecutionFailure(String feedId, String commandName, String json, @Cause Throwable t);
 
+    @LogMessage(level = Logger.Level.ERROR)
+    @Message(id = 3, value = "A feed [%s] opened multiple sessions. This is a violation; closing the extra session")
+    void errorClosingExtraFeedSession(String feedId);
+
+    @LogMessage(level = Logger.Level.ERROR)
+    @Message(id = 4, value = "Cannot close the extra session created by feed [%s]")
+    void errorCannotCloseExtraFeedSession(String feedId, @Cause Throwable t);
+
 }