Created the facilities for transmitting distributed objects and derived

classes over the wire (by inspecting their fields and sending those
directly).


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@8 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/dobj/io/DObjectFactory.java

@@ -1,12 +1,15 @@
 //
-// $Id: DObjectFactory.java,v 1.1 2001/05/29 03:27:59 mdb Exp $
+// $Id: DObjectFactory.java,v 1.2 2001/05/30 00:16:00 mdb Exp $
 
-package com.samskivert.cocktail.cher.dobj;
+package com.samskivert.cocktail.cher.dobj.net;
 
 import java.io.IOException;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
+import java.util.HashMap;
 
+import com.samskivert.cocktail.cher.Log;
+import com.samskivert.cocktail.cher.dobj.DObject;
 import com.samskivert.cocktail.cher.io.ObjectStreamException;
 
 /**
@@ -16,22 +19,40 @@ import com.samskivert.cocktail.cher.io.ObjectStreamException;
  */
 public class DObjectFactory
 {
+    /**
+     * Writes the supplied distributed object out to the specified data
+     * output stream.
+     */
     public static void writeTo (DataOutputStream out, DObject dobj)
         throws IOException
     {
-        // first we write the class of the object to the stream
-        out.writeUTF(dobj.getClass().getName());
-        // then we write the object itself
-        dobj.writeTo(out);
+        Log.info("Marshalling object: " + dobj);
+        // look up the marshaller for this object
+        Class clazz = dobj.getClass();
+        Marshaller marsh = getMarshaller(clazz);
+        // then write the class of the object to the stream
+        out.writeUTF(clazz.getName());
+        // then use the marshaller to write the object itself
+        marsh.writeTo(out, dobj);
     }
 
+    /**
+     * Reads a distributed object from the specified input stream.
+     */
     public static DObject readFrom (DataInputStream in)
         throws IOException
     {
         try {
+            // read in the class name and create an instance of that class
             Class clazz = Class.forName(in.readUTF());
             DObject dobj = (DObject)clazz.newInstance();
-            dobj.readFrom(in);
+            Log.info("Unmarshalling object: " + dobj);
+
+            // look up the marshaller for that class
+            Marshaller marsh = getMarshaller(clazz);
+            // use it to reconstitute the object from the stream
+            marsh.readFrom(in, dobj);
+
             return dobj;
 
         } catch (Exception e) {
@@ -39,4 +60,17 @@ public class DObjectFactory
             throw new ObjectStreamException(errmsg);
         }
     }
+
+    protected static Marshaller getMarshaller (Class clazz)
+        throws IOException
+    {
+        Marshaller marsh = (Marshaller)_marshallers.get(clazz);
+        // create a new marshaller if we don't already have one
+        if (marsh == null) {
+            _marshallers.put(clazz, marsh = new Marshaller(clazz));
+        }
+        return marsh;
+    }
+
+    protected static HashMap _marshallers = new HashMap();
 }

src/java/com/threerings/presents/io/BooleanFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: BooleanFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class BooleanFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public boolean prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeBoolean(field.getBoolean(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setBoolean(dobj, in.readBoolean());
+    }
+}

src/java/com/threerings/presents/io/DoubleFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: DoubleFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class DoubleFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public double prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeDouble(field.getDouble(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setDouble(dobj, in.readDouble());
+    }
+}

src/java/com/threerings/presents/io/FieldMarshaller.java

@@ -0,0 +1,25 @@
+//
+// $Id: FieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+/**
+ * A field marshaller knows how to marshall and unmarshall a particular
+ * data type. It is called upon to do the actual on the wire
+ * encoding/decoding of a field.
+ */
+public interface FieldMarshaller
+{
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException;
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException;
+}

src/java/com/threerings/presents/io/FieldMarshallerRegistry.java

@@ -0,0 +1,67 @@
+//
+// $Id: FieldMarshallerRegistry.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.lang.reflect.Field;
+import java.util.Hashtable;
+import com.samskivert.cocktail.cher.Log;
+
+/**
+ * Field marshaller instances are registered for each type of field that
+ * is supported in a distributed object.
+ */
+public class FieldMarshallerRegistry
+{
+    /**
+     * Returns a field marshaller that can marshall and unmarshall the
+     * specified type of field. If no marshaller is registered for that
+     * field type, an illegal argument exception will be thrown.
+     * Distributed objects must not contain fields that cannot be
+     * transmitted on the wire.
+     */
+    public static FieldMarshaller getMarshaller (Field field)
+    {
+        Class clazz = field.getType();
+        FieldMarshaller marsh = (FieldMarshaller)_registry.get(clazz);
+        if (marsh == null) {
+            String errmsg = "No field marshaller registered for fields " +
+                "of type " + clazz.getName() + ".";
+            throw new IllegalArgumentException(errmsg);
+        }
+        return marsh;
+    }
+
+    /**
+     * Registers the specified field marshaller as the one to use for
+     * fields of the specified class. This assumes that the field
+     * marshaller implementation provides a prototype field of the type it
+     * knows how to marshall by the name of <code>prototype</code>.
+     *
+     * @param clazz the field marshaller class to be registered.
+     */
+    protected static void registerMarshaller (Class clazz)
+    {
+        try {
+            _registry.put(clazz.getField("prototype").getType(),
+                          clazz.newInstance());
+        } catch (Exception e) {
+            Log.warning("Unable to register field marshaller " +
+                        "[class=" + clazz.getName() + "].");
+            Log.logStackTrace(e);
+        }
+    }
+
+    protected static Hashtable _registry = new Hashtable();
+
+    static {
+        // register our field marshallers
+        registerMarshaller(BooleanFieldMarshaller.class);
+        registerMarshaller(ShortFieldMarshaller.class);
+        registerMarshaller(IntFieldMarshaller.class);
+        registerMarshaller(LongFieldMarshaller.class);
+        registerMarshaller(FloatFieldMarshaller.class);
+        registerMarshaller(DoubleFieldMarshaller.class);
+        registerMarshaller(StringFieldMarshaller.class);
+    }
+}

src/java/com/threerings/presents/io/FloatFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: FloatFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class FloatFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public float prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeFloat(field.getFloat(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setFloat(dobj, in.readFloat());
+    }
+}

src/java/com/threerings/presents/io/IntFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: IntFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class IntFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public int prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeInt(field.getInt(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setInt(dobj, in.readInt());
+    }
+}

src/java/com/threerings/presents/io/LongFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: LongFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class LongFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public long prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeLong(field.getLong(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setLong(dobj, in.readLong());
+    }
+}

src/java/com/threerings/presents/io/Marshaller.java

@@ -0,0 +1,113 @@
+//
+// $Id: Marshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.Comparator;
+
+import com.samskivert.cocktail.cher.Log;
+import com.samskivert.cocktail.cher.dobj.DObject;
+import com.samskivert.cocktail.cher.io.ObjectStreamException;
+
+/**
+ * The marshaller inspects the class with which it is constructed and
+ * caches the reflection information it needs to marshall and unmarshall
+ * instances of that class.
+ */
+public class Marshaller
+{
+    public Marshaller (Class clazz)
+    {
+        // we introspect on the class and cache the public data members
+        _fields = clazz.getFields();
+        // sort the fields so that they are written and read in the same
+        // order on all VMs
+        Arrays.sort(_fields, FIELD_COMP);
+
+        // now select field marshallers for each of the fields based on
+        // their type
+        _marshallers = new FieldMarshaller[_fields.length];
+        for (int i = 0; i < _fields.length; i++) {
+            _marshallers[i] =
+                FieldMarshallerRegistry.getMarshaller(_fields[i]);
+            // Log.info("Assigned [field=" + _fields[i] +
+            // ", marshaller=" + _marshallers[i] + "].");
+        }
+    }
+
+    /**
+     * Writes out all of the fields of the specified distributed object to
+     * the supplied data output stream.
+     */
+    public void writeTo (DataOutputStream out, DObject dobj)
+        throws IOException
+    {
+        // we simply iterate over our marshallers, writing each field
+        // out in succession
+        for (int i = 0; i < _fields.length; i++) {
+            try {
+                _marshallers[i].writeTo(out, _fields[i], dobj);
+
+            } catch (IllegalAccessException iae) {
+                // this shouldn't happen because we only attempt to marshall
+                // public fields, but we'll pass it on none the less
+                String errmsg = "Unable to marshall dobj field " +
+                    "[field=" + _fields[i].getName() +
+                    ", dobj=" + dobj  + "].";
+                throw new ObjectStreamException(errmsg);
+            }
+        }
+    }
+
+    /**
+     * Reads in all of the fields of the specified distributed object from
+     * the supplied data input stream.
+     */
+    public void readFrom (DataInputStream in, DObject dobj)
+        throws IOException
+    {
+        // we simply iterate over our marshallers, reading each field in
+        // in succession
+        for (int i = 0; i < _fields.length; i++) {
+            try {
+                _marshallers[i].readFrom(in, _fields[i], dobj);
+
+            } catch (IllegalAccessException iae) {
+                // this shouldn't happen because we only attempt to
+                // unmarshall public fields, but we'll pass it on anyway
+                String errmsg = "Unable to unmarshall dobj field " +
+                    "[field=" + _fields[i].getName() +
+                    ", dobj=" + dobj  + "].";
+                throw new ObjectStreamException(errmsg);
+            }
+        }
+    }
+
+    /**
+     * Used to sort object fields into a predictable order.
+     */
+    protected static class FieldComparator implements Comparator
+    {
+        public int compare (Object o1, Object o2)
+        {
+            return ((Field)o1).getName().compareTo(((Field)o2).getName());
+        }
+
+        public boolean equals (Object obj)
+        {
+            // we don't care about comparing this comparator to others
+            return obj == this;
+        }
+    }
+
+    protected Field[] _fields;
+    protected FieldMarshaller[] _marshallers;
+
+    /** We use this to sort the fields into a predictable order. */
+    protected static final FieldComparator FIELD_COMP = new FieldComparator();
+}

src/java/com/threerings/presents/io/ShortFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: ShortFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class ShortFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public short prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeShort(field.getShort(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.setShort(dobj, in.readShort());
+    }
+}

src/java/com/threerings/presents/io/StringFieldMarshaller.java

@@ -0,0 +1,29 @@
+//
+// $Id: StringFieldMarshaller.java,v 1.1 2001/05/30 00:16:00 mdb Exp $
+
+package com.samskivert.cocktail.cher.dobj.net;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import com.samskivert.cocktail.cher.dobj.DObject;
+
+public class StringFieldMarshaller implements FieldMarshaller
+{
+    /** This is the sort of field that we marshall. */
+    public String prototype;
+
+    public void writeTo (DataOutputStream out, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        out.writeUTF((String)field.get(dobj));
+    }
+
+    public void readFrom (DataInputStream in, Field field, DObject dobj)
+        throws IOException, IllegalAccessException
+    {
+        field.set(dobj, in.readUTF());
+    }
+}

src/java/com/threerings/presents/net/AuthResponse.java

@@ -1,5 +1,5 @@
 //
-// $Id: AuthResponse.java,v 1.3 2001/05/29 03:27:59 mdb Exp $
+// $Id: AuthResponse.java,v 1.4 2001/05/30 00:16:00 mdb Exp $
 
 package com.samskivert.cocktail.cher.net;
 
@@ -7,7 +7,7 @@ import java.io.IOException;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 
-import com.samskivert.cocktail.cher.dobj.DObjectFactory;
+import com.samskivert.cocktail.cher.dobj.net.DObjectFactory;
 
 /**
  * The auth response communicates authentication success or failure as

src/java/com/threerings/presents/net/AuthResponseData.java

@@ -1,5 +1,5 @@
 //
-// $Id: AuthResponseData.java,v 1.2 2001/05/29 03:27:59 mdb Exp $
+// $Id: AuthResponseData.java,v 1.3 2001/05/30 00:16:00 mdb Exp $
 
 package com.samskivert.cocktail.cher.net;
 
@@ -23,17 +23,8 @@ public class AuthResponseData extends DObject
      */
     public String code;
 
-    public void writeTo (DataOutputStream out)
-        throws IOException
+    public String toString ()
     {
-        super.writeTo(out);
-        out.writeUTF(code);
-    }
-
-    public void readFrom (DataInputStream in)
-        throws IOException
-    {
-        super.readFrom(in);
-        code = in.readUTF();
+        return "[code=" + code + "]";
     }
 }

src/java/com/threerings/presents/net/ObjectResponse.java

@@ -1,5 +1,5 @@
 //
-// $Id: ObjectResponse.java,v 1.3 2001/05/29 03:28:50 mdb Exp $
+// $Id: ObjectResponse.java,v 1.4 2001/05/30 00:16:00 mdb Exp $
 
 package com.samskivert.cocktail.cher.net;
 
@@ -8,7 +8,7 @@ import java.io.DataInputStream;
 import java.io.DataOutputStream;
 
 import com.samskivert.cocktail.cher.dobj.DObject;
-import com.samskivert.cocktail.cher.dobj.DObjectFactory;
+import com.samskivert.cocktail.cher.dobj.net.DObjectFactory;
 
 public class ObjectResponse extends DownstreamMessage
 {