Software Development from Ryan

Not a texas holdem server clone, or a party poker clone even, this man from Belgium wants his very own Gpokr Clone.

So aparently serialization was taking 100% of my application
cpu time. I’ve made some changes to the serialization and my apps cpu usage has gone from 100% with about 7 tables running, (approximately 60-80 clients constantaly serializing)
down to 10%. So with the same load on the server the cpu has 90% free
cycles now!

This is from making a few simple changes to
ServerSerializableTypeOracleImpl. Here’s what I did:

1)  Add a new static map to the class…

private static final Map CUSTOM_FIELD_SERIALIZERS = new HashMap();

2)  Add static initialization to the class…

static{
try{
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.boolean_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.boolean_Array_CustomFieldSer­ializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Boolean”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Boolean_CustomFieldSerialize­r”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.byte_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.byte_Array_CustomFieldSerial­izer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Byte”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Byte_CustomFieldSerializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.char_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.char_Array_CustomFieldSerial­izer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Character”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Character_CustomFieldSeriali­zer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.double_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.double_Array_CustomFieldSeri­alizer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Double”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Double_CustomFieldSerializer­”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.float_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.float_Array_CustomFieldSeria­lizer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Float”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Float_CustomFieldSerializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.int_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.int_Array_CustomFieldSeriali­zer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Integer”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Integer_CustomFieldSerialize­r”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.long_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.long_Array_CustomFieldSerial­izer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Long”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Long_CustomFieldSerializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Object_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Object_Array_CustomFieldSeri­alizer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.short_Array”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.short_Array_CustomFieldSeria­lizer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.Short”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.Short_CustomFieldSerializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.lang.String”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.lang.String_CustomFieldSerializer­”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.util.ArrayList”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.util.ArrayList_CustomFieldSeriali­zer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.util.Date”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.util.Date_CustomFieldSerializer”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.util.HashMap”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.util.HashMap_CustomFieldSerialize­r”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.util.HashSet”,
Class.forName(
“com.google.gwt.user.client.rpc.core.java.util.HashSet_CustomFieldSerialize­r”
) );
        CUSTOM_FIELD_SERIALIZERS.put(”java.util.Vector”, Class.forName(
“com.google.gwt.user.client.rpc.core.java.util.Vector_CustomFieldSerializer­”
) );
        } catch (ClassNotFoundException e) {
      // purposely ignored
    }

}

3) Change hasCustomFieldSerializer to use this map….

 public Class hasCustomFieldSerializer(Class instanceType) {
    String qualifiedTypeName;
    if (instanceType.isArray()) {
      Class componentType = instanceType.getComponentType();
      if (componentType.isPrimitive()) {
        qualifiedTypeName = “java.lang.” + componentType.getName();
      } else {
        qualifiedTypeName = Object.class.getName();
      }
      qualifiedTypeName += “_Array”;
    } else {
      qualifiedTypeName = instanceType.getName();
    }
    return (Class)CUSTOM_FIELD_SERIALIZERS.get(qualifiedTypeName);

}

Thats it! Although this limits the custom field serializaers
extensibility it works very well for me since i don’t have any custom
serializers.

The week is off to a good start with a couple big blog posts driving traffic to gpokr keeping the table full with a waiting list most of the day.

jayisgames is a online games blog by Jay Bibby where he keeps very up to date on the latest online games and has generated a quite a large following. He also visted gpokr for a while and chated with his readers and worked his way to a top position on the gpokr top players list. (he’s been bumped down to 11th while writing this),

Also, the Google Web Toolkit Blog made a post today about some of the development that the GWT has been used with and made a mention of gpokr along with some other great work including Mark Roth ’s GWT Hang Man and  Robert Hanson’s GWT Widget Library.

I had some trouble yesterday getting this done. Here's what happened:

1. I installed the jar files, both my jar file and gwt-user in /WEB-INF/lib through ftp. However tomcat loads these jar files when the server is restarted daily at 1am. This is a bit too long to wait for updates. The server does load class files immediatly. So I extracted both jars to /WEB-INF/classes.
2. There was no need to play with a web.xml file. You can access your servlet at http://www.domainname.com/servlet/servletname, (replace domainname and servletname, not servlet).
3. Running an HTTP GET on the servlet worked. So I ran GWT generated javascript to access the server. The RPC call failed. Debugging the javascript showed that it was a 500 Internal server error: Check the server logs for details.
4. Checking the server logs revealed nothing. I Called godaddy a couple times, (thank god for free long distance on skype). They didn't know why the error didn't show up in the logs and the guy I spoke with the second time didn't know what a servlet was.
5. I dug into the GWT source. The RemoteServiceServlet catchs all exceptions in the doPost method and passes them to the respondWithFailure method which adds the exception message to the tomcat log and returns the generic 500 internal error. I modified the source to return the exception and the stack.
6. The exception was a java security restriction on java.lang.reflect and happened in ServerSerializationStream.serializeClass. In this method objects are serialized and each field is set to be accessible, that is if they are private fields they become accessible for serialization. This is what you can't do on godaddy's tomcat. The code is written such that every field's accessibility is changed whether its private or not.
7. Changing the code so that it only sets the accessibility when the field is not accessible allows applications to get by with serializing classes with only public fields when on servers with this type of security restriction. Also, if you only serialized simple types, String, int etc. you most likely won't have this problem, although I haven't tested this.

It's not easy getting out of the ghetto. Today gpokr is moving on up, off my home machine to a hosted account for $6.99/month.

It didn't work for a while but after digging fairly deap there were security restrictions and the GWT source had to be modified and recompiled for the hosting to work.

I work pretty hard most of the time. Sometimes I play poker instead. Sometimes I work and play poker at the same time.

www.gpokr.com is a test of the google web toolkit. It is written completely in java. The interface is compiled down to javascript so it will work in most browsers. The backend is a java servlet running red hat on a virtual machine on my xp box. I know, ghetto. Play a hand. The demo is in alpha so it may break while I'm away, have patience and come back to check out its progress.