From 9d50093bee736d2b7b43756e9a41cfafbd568ee2 Mon Sep 17 00:00:00 2001
From: Alan Young <consult.awy@gmail.com>
Date: Mon, 18 Apr 2016 17:37:46 +0100
Subject: Rework Signals for time and space optimizations

Each Signal* class extends BaseSignal. Each Slot* class extends
BaseSlot.

BaseSignal manages the set of binds associated with it via addBind() and
getBinds() which are called from Signal*. It is optimized for the cases
of zero or one bind, only allocating a HashMap to hold a larger set when
needed.

The interaction with SignalConnection to handle disconnection is
effected via a callback interface rather than another Signal.

Change-Id: Ifa44c1eb40b778c303db947a6e74fe20d1b41a90

diff --git a/src/com/isode/stroke/muc/MUCImpl.java b/src/com/isode/stroke/muc/MUCImpl.java
index 444b331..26be309 100644
--- a/src/com/isode/stroke/muc/MUCImpl.java
+++ b/src/com/isode/stroke/muc/MUCImpl.java
@@ -724,7 +724,7 @@ public class MUCImpl extends MUC {
 	@Override
 	public void disconnect() {
 		if (scopedConnection_ != null) {
-			scopedConnection_.onDestroyed.emit();
+			scopedConnection_.disconnect();
 			scopedConnection_ = null;
 		}
 	}
diff --git a/src/com/isode/stroke/signals/BaseSignal.java b/src/com/isode/stroke/signals/BaseSignal.java
new file mode 100644
index 0000000..de1bd6e
--- /dev/null
+++ b/src/com/isode/stroke/signals/BaseSignal.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2015, Isode Limited, London, England.
+ * All rights reserved.
+ */
+package com.isode.stroke.signals;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/* package */ abstract class BaseSignal implements SignalConnection.DisconnectListener {
+    
+    // Optimized for the case of 0 or 1 bind
+    private SignalConnection connection_;
+    private BaseSlot bind_;
+    private Map<SignalConnection, BaseSlot> binds_;
+    
+    protected final synchronized SignalConnection addBind(final BaseSlot bind) {
+        final SignalConnection connection = new SignalConnection(this);
+        if (binds_ != null) {
+            binds_.put(connection, bind);
+        } else if (connection_ != null) {
+            binds_ = new HashMap<SignalConnection, BaseSlot>();
+            binds_.put(connection_, bind_);
+            connection_ = null;
+            bind_ = null;
+            binds_.put(connection, bind);
+        } else {
+            connection_ = connection;
+            bind_ = bind;
+        }
+        return connection;
+    }
+    
+    protected final synchronized BaseSlot[] getBinds() {
+        if (binds_ != null) {
+            return binds_.values().toArray(new BaseSlot[binds_.size()]);
+        } else if (connection_ != null) {
+            return new BaseSlot[]{bind_};
+        } else {
+            return null; // return null rather than allocate an empty array
+        }
+    }
+    
+    @Override
+    public final synchronized void onSignalConnectionDisconnect(final SignalConnection connection) {
+        if (binds_ != null) {
+            binds_.remove(connection);
+        } else if (connection_ == connection) {
+            connection_ = null;
+            bind_ = null;
+        }
+    }
+
+    public final synchronized void disconnectAll() {
+        if (binds_ != null) {
+            binds_.clear();
+        } else {
+            connection_ = null;
+            bind_ = null;
+        }
+    }
+}
diff --git a/src/com/isode/stroke/signals/BaseSlot.java b/src/com/isode/stroke/signals/BaseSlot.java
new file mode 100644
index 0000000..9b8ac13
--- /dev/null
+++ b/src/com/isode/stroke/signals/BaseSlot.java
@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2015, Isode Limited, London, England.
+ * All rights reserved.
+ */
+package com.isode.stroke.signals;
+
+/* package */ interface BaseSlot {
+
+}
diff --git a/src/com/isode/stroke/signals/Signal.java b/src/com/isode/stroke/signals/Signal.java
index cfa8665..1821cb0 100644
--- a/src/com/isode/stroke/signals/Signal.java
+++ b/src/com/isode/stroke/signals/Signal.java
@@ -1,31 +1,17 @@
 /*
- * Copyright (c) 2010, Isode Limited, London, England.
+ * Copyright (c) 2010-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
 
 /**
  * An approximation of the boost::signals system, although a little more warty.
  */
-public class Signal {
-
-    private final Map<SignalConnection, Slot> binds_ = Collections.synchronizedMap(new HashMap<SignalConnection, Slot>());
+public final class Signal extends BaseSignal {
 
     public SignalConnection connect(Slot bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connectWithoutReturn(new Slot() {
-
-            public void call() {
-                binds_.remove(connection);
-            }
-        });
-        return connection;
+        return addBind(bind);
     }
 
     public SignalConnection connect(final Signal target) {
@@ -36,19 +22,12 @@ public class Signal {
         });
     }
 
-    void connectWithoutReturn(Slot bind) {
-        binds_.put(null, bind);
-    }
-
     public void emit() {
-        ArrayList<Slot> binds = new ArrayList<Slot>();
-        binds.addAll(binds_.values());
-        for (Slot bind : binds) {
-            bind.call();
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot)bind).call();
         }
     }
 
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/Signal1.java b/src/com/isode/stroke/signals/Signal1.java
index c799d4c..9787096 100644
--- a/src/com/isode/stroke/signals/Signal1.java
+++ b/src/com/isode/stroke/signals/Signal1.java
@@ -1,36 +1,25 @@
 /*
- * Copyright (c) 2010, Isode Limited, London, England.
+ * Copyright (c) 2010-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
 
 /**
  * An approximation of the boost::signals system, although a little more warty.
  */
-public class Signal1<T1> {
-    private final Map<SignalConnection, Slot1<T1> > binds_ = Collections.synchronizedMap(new HashMap<SignalConnection, Slot1<T1> >());
+public final class Signal1<T1> extends BaseSignal {
     public SignalConnection connect(Slot1<T1> bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connect(new Slot() {
-           public void call() {
-               binds_.remove(connection);
-           }
-        });
-        return connection;
+        return addBind(bind);
     }
 
+    @SuppressWarnings("unchecked")
     public void emit(T1 p1) {
-        ArrayList<Slot1<T1>> binds = new ArrayList<Slot1<T1>>();
-        binds.addAll(binds_.values());
-        for (Slot1<T1> bind : binds) {
-            bind.call(p1);
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot1<T1>)bind).call(p1);
         }
     }
 
@@ -41,8 +30,4 @@ public class Signal1<T1> {
             }
         });
     }
-
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/Signal2.java b/src/com/isode/stroke/signals/Signal2.java
index fa3c4b5..72c9de0 100644
--- a/src/com/isode/stroke/signals/Signal2.java
+++ b/src/com/isode/stroke/signals/Signal2.java
@@ -1,40 +1,25 @@
 /*
- * Copyright (c) 2010, Isode Limited, London, England.
+ * Copyright (c) 2010-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
 
 /**
  * An approximation of the boost::signals system, although a little more warty.
  */
-public class Signal2<T1, T2> {
-    private final Map<SignalConnection, Slot2<T1, T2> > binds_ = Collections.synchronizedMap(new HashMap<SignalConnection, Slot2<T1, T2> >());
+public class Signal2<T1, T2> extends BaseSignal {
     public SignalConnection connect(Slot2<T1, T2> bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connect(new Slot() {
-           public void call() {
-               binds_.remove(connection);
-           }
-        });
-        return connection;
+        return addBind(bind);
     }
 
+    @SuppressWarnings("unchecked")
     public void emit(T1 p1, T2 p2) {
-        ArrayList<Slot2<T1,T2>> binds = new ArrayList<Slot2<T1, T2>>();
-        binds.addAll(binds_.values());
-        for (Slot2<T1, T2> bind : binds) {
-            bind.call(p1, p2);
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot2<T1, T2>)bind).call(p1, p2);
         }
     }
-
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/Signal3.java b/src/com/isode/stroke/signals/Signal3.java
index b9151dc..014f047 100644
--- a/src/com/isode/stroke/signals/Signal3.java
+++ b/src/com/isode/stroke/signals/Signal3.java
@@ -1,15 +1,10 @@
 /*
- * Copyright (c) 2012, Isode Limited, London, England.
+ * Copyright (c) 2010-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
 
 /**
  * An approximation of the boost::signals system with 3 parameters
@@ -17,24 +12,14 @@ import java.util.Map;
  * @param <T2> Type 2
  * @param <T3> Type 3
  */
-public class Signal3<T1, T2, T3> {
-    private final Map<SignalConnection, Slot3<T1, T2,T3> > binds_ = Collections.synchronizedMap(
-            new HashMap<SignalConnection, Slot3<T1, T2,T3> >());
-
+public class Signal3<T1, T2, T3> extends BaseSignal {
     /**
      * Add a slot which will be notified
      * @param bind slot, not null
      * @return signal connection
      */
     public SignalConnection connect(Slot3<T1, T2,T3> bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connect(new Slot() {
-            public void call() {
-                binds_.remove(connection);
-            }
-        });
-        return connection;
+        return addBind(bind);
     }
 
     /**
@@ -43,18 +28,12 @@ public class Signal3<T1, T2, T3> {
      * @param p2 parameter value 2
      * @param p3 parameter value 3
      */
-    public void emit(T1 p1, T2 p2,T3 p3) {
-        List<Slot3<T1,T2, T3>> binds = new ArrayList<Slot3<T1, T2, T3>>();
-        binds.addAll(binds_.values());
-        for (Slot3<T1, T2, T3> bind : binds) {
-            bind.call(p1, p2, p3);
+    @SuppressWarnings("unchecked")
+    public void emit(T1 p1, T2 p2, T3 p3) {
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot3<T1, T2, T3>)bind).call(p1, p2, p3);
         }
     }
-
-    /**
-     * Remove all slots(listeners) 
-     */
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/Signal4.java b/src/com/isode/stroke/signals/Signal4.java
index 6a29641..edf30ed 100644
--- a/src/com/isode/stroke/signals/Signal4.java
+++ b/src/com/isode/stroke/signals/Signal4.java
@@ -1,18 +1,10 @@
 /*
- * Copyright (c) 2012-2013, Isode Limited, London, England.
+ * Copyright (c) 2012-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import com.isode.stroke.signals.SignalConnection;
-import com.isode.stroke.signals.Slot;
 
 
 /**
@@ -22,24 +14,14 @@ import com.isode.stroke.signals.Slot;
  * @param <T3> Type 3
  * @param <T4> Type 4
  */
-public class Signal4<T1, T2, T3, T4> {
-    private final Map<SignalConnection, Slot4<T1, T2, T3, T4> > binds_ = Collections.synchronizedMap(
-            new HashMap<SignalConnection, Slot4<T1, T2, T3, T4> >());
-
+public class Signal4<T1, T2, T3, T4> extends BaseSignal {
     /**
      * Add a slot which will be notified
      * @param bind slot, not null
      * @return signal connection
      */
     public SignalConnection connect(Slot4<T1, T2, T3, T4> bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connect(new Slot() {
-            public void call() {
-                binds_.remove(connection);
-            }
-        });
-        return connection;
+        return addBind(bind);
     }
 
     /**
@@ -49,18 +31,12 @@ public class Signal4<T1, T2, T3, T4> {
      * @param p3 parameter value 3
      * @param p4 parameter value 4
      */
+    @SuppressWarnings("unchecked")
     public void emit(T1 p1, T2 p2, T3 p3, T4 p4) {
-        List<Slot4<T1, T2, T3, T4>> binds = new ArrayList<Slot4<T1, T2, T3, T4>>();
-        binds.addAll(binds_.values());
-        for (Slot4<T1, T2, T3, T4> bind : binds) {
-            bind.call(p1, p2, p3, p4);
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot4<T1, T2, T3, T4>)bind).call(p1, p2, p3, p4);
         }
     }
-
-    /**
-     * Remove all slots(listeners)
-     */
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/Signal7.java b/src/com/isode/stroke/signals/Signal7.java
index 296cc02..bbf6559 100644
--- a/src/com/isode/stroke/signals/Signal7.java
+++ b/src/com/isode/stroke/signals/Signal7.java
@@ -5,14 +5,6 @@
 
 package com.isode.stroke.signals;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import com.isode.stroke.signals.SignalConnection;
-import com.isode.stroke.signals.Slot;
 
 
 /**
@@ -22,24 +14,14 @@ import com.isode.stroke.signals.Slot;
  * @param <T3> Type 3
  * @param <T4> Type 4
  */
-public class Signal7<T1, T2, T3, T4, T5, T6, T7> {
-    private final Map<SignalConnection, Slot7<T1, T2, T3, T4, T5, T6, T7> > binds_ = Collections.synchronizedMap(
-            new HashMap<SignalConnection, Slot7<T1, T2, T3, T4, T5, T6, T7> >());
-
+public class Signal7<T1, T2, T3, T4, T5, T6, T7> extends BaseSignal {
     /**
      * Add a slot which will be notified
      * @param bind slot, not null
      * @return signal connection
      */
     public SignalConnection connect(Slot7<T1, T2, T3, T4, T5, T6, T7> bind) {
-        final SignalConnection connection = new SignalConnection();
-        binds_.put(connection, bind);
-        connection.onDestroyed.connect(new Slot() {
-            public void call() {
-                binds_.remove(connection);
-            }
-        });
-        return connection;
+        return addBind(bind);
     }
 
     /**
@@ -49,18 +31,12 @@ public class Signal7<T1, T2, T3, T4, T5, T6, T7> {
      * @param p3 parameter value 3
      * @param p4 parameter value 4
      */
+    @SuppressWarnings("unchecked")
     public void emit(T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6, T7 p7) {
-        List<Slot7<T1, T2, T3, T4, T5, T6, T7>> binds = new ArrayList<Slot7<T1, T2, T3, T4, T5, T6, T7>>();
-        binds.addAll(binds_.values());
-        for (Slot7<T1, T2, T3, T4, T5, T6, T7> bind : binds) {
-            bind.call(p1, p2, p3, p4, p5, p6, p7);
+        final BaseSlot[] binds = getBinds();
+        if (binds == null) {return;}
+        for (BaseSlot bind : binds) {
+            ((Slot7<T1, T2, T3, T4, T5, T6, T7>)bind).call(p1, p2, p3, p4, p5, p6, p7);
         }
     }
-
-    /**
-     * Remove all slots(listeners)
-     */
-    public void disconnectAll() {
-        binds_.clear();
-    }
 }
diff --git a/src/com/isode/stroke/signals/SignalConnection.java b/src/com/isode/stroke/signals/SignalConnection.java
index 452c80b..30bbf82 100644
--- a/src/com/isode/stroke/signals/SignalConnection.java
+++ b/src/com/isode/stroke/signals/SignalConnection.java
@@ -1,15 +1,22 @@
 /*
- * Copyright (c) 2010, Isode Limited, London, England.
+ * Copyright (c) 2010-2015, Isode Limited, London, England.
  * All rights reserved.
  */
 
 package com.isode.stroke.signals;
 
-
 public class SignalConnection {
-    public final Signal onDestroyed = new Signal();
-
+    interface DisconnectListener {
+        void onSignalConnectionDisconnect(SignalConnection connection);
+    }
+    
+    private final DisconnectListener listener;
+    
+    SignalConnection(DisconnectListener listener) {
+        this.listener = listener;
+    }
+    
     public void disconnect() {
-        onDestroyed.emit();
+        listener.onSignalConnectionDisconnect(this);
     }
 }
diff --git a/src/com/isode/stroke/signals/Slot.java b/src/com/isode/stroke/signals/Slot.java
index 35b8c70..780892d 100644
--- a/src/com/isode/stroke/signals/Slot.java
+++ b/src/com/isode/stroke/signals/Slot.java
@@ -8,6 +8,6 @@ package com.isode.stroke.signals;
 /**
  * Bind class for connecting to a signal.
  */
-public interface Slot {
+public interface Slot extends BaseSlot {
     void call();
 }
diff --git a/src/com/isode/stroke/signals/Slot1.java b/src/com/isode/stroke/signals/Slot1.java
index a8f0179..001dca7 100644
--- a/src/com/isode/stroke/signals/Slot1.java
+++ b/src/com/isode/stroke/signals/Slot1.java
@@ -8,6 +8,6 @@ package com.isode.stroke.signals;
 /**
  * Bind class for connecting to a signal.
  */
-public interface Slot1<T1> {
+public interface Slot1<T1> extends BaseSlot {
     void call(T1 p1);
 }
diff --git a/src/com/isode/stroke/signals/Slot2.java b/src/com/isode/stroke/signals/Slot2.java
index b3b9330..03eb9a6 100644
--- a/src/com/isode/stroke/signals/Slot2.java
+++ b/src/com/isode/stroke/signals/Slot2.java
@@ -8,6 +8,6 @@ package com.isode.stroke.signals;
 /**
  * Bind class for connecting to a signal.
  */
-public interface Slot2<T1, T2> {
+public interface Slot2<T1, T2> extends BaseSlot {
     void call(T1 p1, T2 p2);
 }
diff --git a/src/com/isode/stroke/signals/Slot3.java b/src/com/isode/stroke/signals/Slot3.java
index ee5ccbc..63c371c 100644
--- a/src/com/isode/stroke/signals/Slot3.java
+++ b/src/com/isode/stroke/signals/Slot3.java
@@ -11,7 +11,7 @@ package com.isode.stroke.signals;
  * @param <T2> Type 2
  * @param <T3> Type 3
  */
-public interface Slot3<T1, T2,T3> {
+public interface Slot3<T1, T2,T3> extends BaseSlot {
     /**
      * This method will be called on notification from a signal
      * @param p1 parameter value 1
diff --git a/src/com/isode/stroke/signals/Slot4.java b/src/com/isode/stroke/signals/Slot4.java
index 02e6fd9..93401db 100644
--- a/src/com/isode/stroke/signals/Slot4.java
+++ b/src/com/isode/stroke/signals/Slot4.java
@@ -12,7 +12,7 @@ package com.isode.stroke.signals;
  * @param <T3> Type 3
  * @param <T4> Type 4
  */
-public interface Slot4<T1, T2, T3, T4> {
+public interface Slot4<T1, T2, T3, T4> extends BaseSlot {
     /**
      * This method will be called on notification from a signal
      * @param p1 parameter value 1
diff --git a/src/com/isode/stroke/signals/Slot7.java b/src/com/isode/stroke/signals/Slot7.java
index 7df6973..752d9a8 100644
--- a/src/com/isode/stroke/signals/Slot7.java
+++ b/src/com/isode/stroke/signals/Slot7.java
@@ -15,7 +15,7 @@ package com.isode.stroke.signals;
  * @param <T6> Type 6
  * @param <T7> Type 7
  */
-public interface Slot7<T1, T2, T3, T4, T5, T6, T7> {
+public interface Slot7<T1, T2, T3, T4, T5, T6, T7> extends BaseSlot {
     /**
      * This method will be called on notification from a signal
      * @param p1 parameter value 1
-- 
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