About The Project

ConcurrentHashMap with indexing technology that improve performance. Used as an in-memory key-value database for Objects.

Getting Started

1. Clone the repository

   git clone https://github.com/keich/IndexedHashMap.git

2. Install NPM packages

   npm install

3. Add dependency to your project

  	<dependency>
  		<groupId>ru.keich.mon</groupId>
  		<artifactId>IndexedHashMap</artifactId>
  		<version>0.2.0</version>
  	</dependency>

Usage

1. Create class extended BaseEntity

	public static class TestEntity {
	    private final String name;
	    private final Long version;

	    public TestEntity(String name, Long version) {
	        this.name = name;
	        this.version = version;
	    }
	    
	    public static final String FIELD_NAME = "name";
	    
	    public String getName() {
	    	return name;
	    }
	      
	    public static Set<Object> getNameForIndex(TestEntity e) {
	        return Collections.singleton(e.getName());
	    } 
	}

2. Create instance of IndexedHashMap

IndexedHashMap<String, TestEntity> store = new IndexedHashMap<>(null,"DBName");

3. Put and get data

		TestEntity entity = new TestEntity("Hello word", 1L);
		store.put("key1", entity);
		TestEntity result = store.get("key1");

4. Lock object for insert or update

		store.compute("key1", (k, obj) -> {
		    // Object with key1 missing
		    if(obj == null) {
		        //Insert
		        return new TestEntity("Hello word", 1L);
		    }
		    // Object exists
		    // Replace
		    return new TestEntity("Hello word 2", 1L);
		    // Or remove
		    //return null;
		});

Work with indexes

1. Determine what data to put in the index

public static final String FIELD_NAME = "name";
      
public static Set<Object> getNameForIndex(TestEntity e) {
	return Collections.singleton(e.getName());
}       

2. Do before insert data

store.addIndexEqual(TestEntity.FIELD_NAME, TestEntity::getNameForIndex);

3. Query objects from store

QueryPredicate repdicate = QueryPredicate.notEqual(TestEntity.FIELD_NAME, "Hello world");
Set<String> result = store.keySet(repdicate);
result.forEach(key -> {
	System.out.println(store.get(key));
});

Index data type support

Any object with hash and equal or any object implements Comparable.(depends on predicate)

Operator	Description	Long	Class String	Class Map.Entry	Class Set
EQ	Equal	ok	ok	The key is equal and the value is equal	A object in set is equal the specified object
NE	Not equal	ok	ok	Undefined behavior	Undefined behavior. Use NI
LT	Less than	ok	ok	Exception	Exception
GT	Gather than	ok	ok	Exception	Exception
GE	Gather equal	ok	ok	Exception	Exception
CO	Contain(Like)	Undefined behavior	The string contains the specified string	The key is equal and the value contains the specified string	A string in the set contains the specified string
NC	Not contain(Not Like)	Undefined behavior	Vice versa CO	The key is equal and the value not contains the specified string	Undefined behavior
NI	Not include(uses for Set)	Undefined behavior	Vice versa CO	Undefined behavior	Return object with set not contains object

Index types

Index class	Description
IndexEqual	Index from HashMap
IndexLongUniq	Index from TreeMap for uniq Long values
IndexSorted	Index from TreeMap for a objects implements Comparable
IndexSortedUniq	Index from TreeMap for uniq a objects implements Comparable
IndexSmallInt	Index for Integer with small range(Uses array)

Work without indexes

1. Do before insert data

store.addQueryField(TestEntity.FIELD_NAME, TestEntity::getSomeSetForIndex);

2. Query objects from store

QueryPredicate predicate = Predicates.notEqual(TestEntity.FIELD_NAME, "Hello world");
Set<String> result = store.keySet(predicate);
result.forEach(key -> {
	System.out.println(store.get(key));
});