Abstract state stuff into new ServerStatus class, provide much more useful debugging and enforce legal state transitions

Issue 1767

git-svn-id: http://svn.dmdirc.com/trunk@4766 00569f92-eb28-0410-84fd-f71c24880f

src/com/dmdirc/Server.java

@@ -99,7 +99,8 @@ public final class Server extends WritableFrameContainer implements Serializable
     private transient Identity profile;
 
     /** The current state of this server. */
-    private ServerState myState = ServerState.DISCONNECTED;
+    private final ServerStatus myState = new ServerStatus();
+
     /** The timer we're using to delay reconnects. */
     private Timer reconnectTimer;
 
@@ -238,7 +239,7 @@ public final class Server extends WritableFrameContainer implements Serializable
         assert profile != null;
 
         synchronized (this) {
-            switch (myState) {
+            switch (myState.getState()) {
                 case RECONNECT_WAIT:
                     reconnectTimer.cancel();
                     break;
@@ -262,7 +263,7 @@ public final class Server extends WritableFrameContainer implements Serializable
                         + "is still connected.\n\nMy state:" + myState);
             }
             
-            myState = ServerState.CONNECTING;
+            myState.transition(ServerState.CONNECTING);
         
             ActionManager.processEvent(CoreActionType.SERVER_CONNECTING, null, this);
 
@@ -327,7 +328,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      */
     public void reconnect(final String reason) {
         synchronized (this) {
-            if (myState == ServerState.CLOSING) {
+            if (myState.getState() == ServerState.CLOSING) {
                 return;
             }
         
@@ -358,7 +359,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      */
     public void disconnect(final String reason) {
         synchronized (this) {
-            switch (myState) {
+            switch (myState.getState()) {
             case CLOSING:
             case DISCONNECTED:
             case TRANSIENTLY_DISCONNECTED:
@@ -370,13 +371,13 @@ public final class Server extends WritableFrameContainer implements Serializable
                 break;
             }
 
-            myState = ServerState.DISCONNECTING;
+            myState.transition(ServerState.DISCONNECTING);
         
             removeInvites();
             updateIcon();
 
             if (parser == null) {
-                myState = ServerState.DISCONNECTED;
+                myState.transition(ServerState.DISCONNECTED);
             } else {
                 parser.disconnect(reason);
             }
@@ -401,7 +402,7 @@ public final class Server extends WritableFrameContainer implements Serializable
     @Precondition("The server state is transiently disconnected")
     private void doDelayedReconnect() {
         synchronized (this) {
-            if (myState != ServerState.TRANSIENTLY_DISCONNECTED) {
+            if (myState.getState() != ServerState.TRANSIENTLY_DISCONNECTED) {
                 throw new IllegalStateException("doDelayedReconnect when not "
                         + "transiently disconnected\n\nState: " + myState);
             }
@@ -416,15 +417,15 @@ public final class Server extends WritableFrameContainer implements Serializable
                 @Override
                 public void run() {
                     synchronized (Server.this) {
-                        if (myState == ServerState.RECONNECT_WAIT) {
-                            myState = ServerState.TRANSIENTLY_DISCONNECTED;
+                        if (myState.getState() == ServerState.RECONNECT_WAIT) {
+                            myState.transition(ServerState.TRANSIENTLY_DISCONNECTED);
                             reconnect();
                         }
                     }
                 }
             }, delay);
 
-            myState = ServerState.RECONNECT_WAIT;
+            myState.transition(ServerState.RECONNECT_WAIT);
             updateIcon();
         }
     }
@@ -560,7 +561,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      */
     public void addChannel(final ChannelInfo chan) {
         synchronized (this) {
-            if (myState == ServerState.CLOSING) {
+            if (myState.getState() == ServerState.CLOSING) {
                 // Can't join channels while the server is closing
                 return;
             }
@@ -585,7 +586,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      */
     public void addQuery(final String host) {
         synchronized (this) {
-            if (myState == ServerState.CLOSING) {
+            if (myState.getState() == ServerState.CLOSING) {
                 // Can't open queries while the server is closing
                 return;
             }
@@ -660,7 +661,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      * Updates this server's icon.
      */
     private void updateIcon() {
-        final String icon = myState == ServerState.CONNECTED
+        final String icon = myState.getState() == ServerState.CONNECTED
                     ? serverInfo.getSSL() ? "secure-server" : "server"
                     : "server-disconnected";
         setIcon(icon);
@@ -709,7 +710,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      */
     public void join(final String channel) {
         synchronized (this) {
-            if (myState == ServerState.CONNECTED) {
+            if (myState.getState() == ServerState.CONNECTED) {
                 removeInvites(channel);
 
                 if (hasChannel(channel)) {
@@ -728,7 +729,7 @@ public final class Server extends WritableFrameContainer implements Serializable
     @Override
     public void sendLine(final String line) {
         synchronized (this) {
-            if (parser != null && myState == ServerState.CONNECTED) {
+            if (parser != null && myState.getState() == ServerState.CONNECTED) {
                 parser.sendLine(window.getTranscoder().encode(line));
             }
         }
@@ -877,7 +878,7 @@ public final class Server extends WritableFrameContainer implements Serializable
      * @return This server's state
      */
     public ServerState getState() {
-        return myState;
+        return myState.getState();
     }
 
     /** {@inheritDoc} */
@@ -895,7 +896,7 @@ public final class Server extends WritableFrameContainer implements Serializable
                 disconnect();
             }
 
-            myState = ServerState.CLOSING;
+            myState.transition(ServerState.CLOSING);
             closeChannels();
             closeQueries();
             removeInvites();
@@ -1138,15 +1139,16 @@ public final class Server extends WritableFrameContainer implements Serializable
         eventHandler.unregisterCallbacks();
 
         synchronized (this) {
-            if (myState == ServerState.CLOSING || myState == ServerState.DISCONNECTED) {
+            if (myState.getState() == ServerState.CLOSING
+                    || myState.getState() == ServerState.DISCONNECTED) {
                 // This has been triggered via .disconect()
                 return;
             }
             
-            if (myState == ServerState.DISCONNECTING) {
-                myState = ServerState.DISCONNECTED;
+            if (myState.getState() == ServerState.DISCONNECTING) {
+                myState.transition(ServerState.DISCONNECTED);
             } else {
-                myState = ServerState.TRANSIENTLY_DISCONNECTED;
+                myState.transition(ServerState.TRANSIENTLY_DISCONNECTED);
             }
 
             updateIcon();
@@ -1168,7 +1170,7 @@ public final class Server extends WritableFrameContainer implements Serializable
 
             if (getConfigManager().getOptionBool(DOMAIN_GENERAL,
                     "reconnectondisconnect", false)
-                    && myState == ServerState.TRANSIENTLY_DISCONNECTED) {
+                    && myState.getState() == ServerState.TRANSIENTLY_DISCONNECTED) {
                 doDelayedReconnect();
             }        
         }
@@ -1182,16 +1184,17 @@ public final class Server extends WritableFrameContainer implements Serializable
     @Precondition("The current server state is CONNECTING")
     public void onConnectError(final ParserError errorInfo) {
         synchronized (this) {
-            if (myState == ServerState.CLOSING || myState == ServerState.DISCONNECTING) {
+            if (myState.getState() == ServerState.CLOSING
+                    || myState.getState() == ServerState.DISCONNECTING) {
                 // Do nothing
                 return;
-            } else if (myState != ServerState.CONNECTING) {
+            } else if (myState.getState() != ServerState.CONNECTING) {
                 // Shouldn't happen
                 throw new IllegalStateException("Connect error when not "
                         + "connecting\n\nState: " + myState);
             }
 
-            myState = ServerState.TRANSIENTLY_DISCONNECTED;
+            myState.transition(ServerState.TRANSIENTLY_DISCONNECTED);
         
             updateIcon();
 
@@ -1251,13 +1254,13 @@ public final class Server extends WritableFrameContainer implements Serializable
     @Precondition("State is CONNECTING")
     public void onPost005() {
         synchronized (this) {
-            if (myState != ServerState.CONNECTING) {
+            if (myState.getState() != ServerState.CONNECTING) {
                 // Shouldn't happen
                 throw new IllegalStateException("Received onPost005 while not "
                         + "connecting\n\nState: " + myState);
             }
             
-            myState = ServerState.CONNECTED;
+            myState.transition(ServerState.CONNECTED);
         
             updateIcon();
 

src/com/dmdirc/ServerState.java

@@ -22,20 +22,81 @@
 
 package com.dmdirc;
 
-/** An enumeration of possible states for servers. */
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * An enumeration of possible states for servers.
+ */
 public enum ServerState {
+
     /** Indicates the client is in the process of connecting. */
-    CONNECTING,
+    CONNECTING(
+            "CONNECTED",                 // Connection attempt succeeded
+            "TRANSIENTLY_DISCONNECTED",  // Connection attempt failed
+            "DISCONNECTING",             // User ordered a disconnection
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** Indicates the client has connected to the server. */
-    CONNECTED,
+    CONNECTED(
+            "DISCONNECTING",             // User ordered a disconnection
+            "TRANSIENTLY_DISCONNECTED",  // Server caused a disconnection
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** Indicates that we've been temporarily disconnected. */
-    TRANSIENTLY_DISCONNECTED,
+    TRANSIENTLY_DISCONNECTED(
+            "CONNECTING",                // User forced a connect attempt
+            "RECONNECT_WAIT",            // Waiting for auto-reconnect
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** Indicates that the user has told us to disconnect. */
-    DISCONNECTED,
+    DISCONNECTED(
+            "CONNECTING",                // User forced a connect attempt
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** In the process of disconnecting. */
-    DISCONNECTING,
+    DISCONNECTING(
+            "DISCONNECTED",              // Socket closed
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** Indicates we're waiting for the auto-reconnect timer to fire. */
-    RECONNECT_WAIT,
+    RECONNECT_WAIT(
+            "CONNECTING",                // User forced a connect attempt
+            "TRANSIENTLY_DISCONNECTED",  // Reconnect timer expired
+            "CLOSING"                    // DMDirc is closing
+    ),
+
     /** Indicates that the server frame and its children are closing. */
-    CLOSING,
+    CLOSING;
+
+    /** The allowed transitions from this state. */
+    private final List<String> transitions;
+
+    /**
+     * Creates a new instance of ServerState.
+     *
+     * @since 0.6.3
+     * @param transitions The names of the states to which a transition is
+     * allowed from this state
+     */
+    ServerState(final String ... transitions) {
+        this.transitions = Arrays.asList(transitions);
+    }
+
+    /**
+     * Determines whether a transition from this state to the specified state
+     * would be legal.
+     *
+     * @since 0.6.3
+     * @param state The state that is being transitioned to
+     * @return True if the transition is allowed, false otherwise.
+     */
+    public boolean canTransitionTo(final ServerState state) {
+        return transitions.contains(state.name());
+    }
 }

src/com/dmdirc/ServerStatus.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2006-2008 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc;
+
+import com.dmdirc.util.RollingList;
+
+/**
+ * Describes the status of a server and manages transitions between different
+ * states.
+ *
+ * @since 0.6.3
+ * @author chris
+ */
+public class ServerStatus {
+
+    /** The current state of the server. */
+    protected ServerState state = ServerState.DISCONNECTED;
+
+    /** A history of transactions for debugging purposes. */
+    protected RollingList<String> history = new RollingList<String>(10);
+
+    /**
+     * Transitions the status of this object to the specified state.
+     *
+     * @param newState The state to transition to
+     */
+    public synchronized void transition(final ServerState newState) {
+        addHistoryEntry(state, newState);
+
+        if (state.canTransitionTo(newState)) {
+            state = newState;
+        } else {
+            throw new IllegalArgumentException("Illegal server state "
+                    + "transition\n\n" + getTransitionHistory());
+        }
+    }
+
+    /**
+     * Retrieves the current state of this status object.
+     *
+     * @return This object's current state
+     */
+    public synchronized ServerState getState() {
+        return state;
+    }
+
+    /**
+     * Adds a history entry to this status object. The history entry contains
+     * the name of the states being transitioned between, the details of the
+     * method (and class and line) which initiated the transition, and the
+     * name of the thread in which the transition is occuring.
+     *
+     * @param fromState The state which is being transitioned from
+     * @param toState The state which is being transitioned to
+     */
+    protected void addHistoryEntry(final ServerState fromState, final ServerState toState) {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(fromState.name());
+        builder.append('→');
+        builder.append(toState.name());
+        builder.append(' ');
+        builder.append(Thread.currentThread().getStackTrace()[2].toString());
+        builder.append(" [");
+        builder.append(Thread.currentThread().getName());
+        builder.append(']');
+
+        history.add(builder.toString());
+    }
+
+    /**
+     * Retrieves the transition history of this status object as a string.
+     *
+     * @see #addHistoryEntry(com.dmdirc.ServerState, com.dmdirc.ServerState)
+     * @return A line feed ('\n') delimited string containing one entry for
+     * each of the entries in this status's transition history.
+     */
+    public String getTransitionHistory() {
+        final StringBuilder builder = new StringBuilder();
+
+        for (String line : history.getList()) {
+            if (builder.length() > 0) {
+                builder.append('\n');
+            }
+
+            builder.append(line);
+        }
+
+        return builder.toString();
+    }
+
+}