k0smik0 / jbbp

Persister based on Java BerkeleyDB

#JBBP - Java BerkeleyDB Based Persister

This is a persister using Java BerkeleyDB.

BerkeleyDB is a key-value DB, supporting full ACID transactions, DPL Java access, multi-threading model but single process based, keyed and sequential data retrieval, and so on.

However, using BerkeleyDB requires some annoying boilerplate codes in order to setup a production environment, so I wrote JBBP, a proxy/wrapper for BerkeleyDB under the hood.

Some examples:

• create:

MyUser myUser = ...;
persister.create(myUser);

• update:

MyUser myUser = ...;
persister.update(myUser.getId(), myUser);

Agreeing with BerkeleyDB architecture, Value object, properly annotated, has to provide a unique id (for internal keys mapping), so MyUser could be something as:

@Entity
public class MyUser {
    @PrimaryKey
    private String id;

    ...
}

(Only native and String type are supported for PrimaryKey)

• sequential retrieve (using Java8 lambdas):

persister.valuesIterator()
.forEachRemaining( a->myMap.put(a.getUid(), a) );

Setup How-To

#####1 Extends Helper (inheriting BerkeleyDBAutoCommittableHelper or BerkeleyDBTransactionableHelper):

// first generics parameter is String => Key type is String
public class YourHelper<Y extends YourValueObject> 
extends BerkeleyDBAutoCommittableHelper<String,Y> { // <- note "String" type
    public YourDBAutoCommittableHelper(String yourCorpusName, String yourSiloName) { ... }
...
}

Using AutoCommittableHelper each operations (create/put/delete) will be persisted immediately; using TransactionableHelper you must begin your persisting area codes with persister.beginTransaction(); and end with persister.commit();

#####2 Extends Persister, specifying key and value type (key is first parameter, value the second one):

public class YourPersister<Y extends YourValueObject> extends Persister<String, Y> {
    public YourPersister(YourHelper<Y> yourHelper, Class<Y> valueClass) {
        // second parameter is String, because key type is string, coherently with Helper
    	super(yourHelper, String.class, valueClass);
    }
}

#####3 Use persister as showed in examples ;D

ps: obviously, you could use Guice to inject dependencies easily.

Enjoy it ;D !