OpenHFT/Java-Lang

Java Language support http://chronicle.software

Download

Step 1. Add the JitPack repository to your build file

Add it in your root settings.gradle at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url 'https://jitpack.io' }
		}
	}

Add it in your settings.gradle.kts at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url = uri("https://jitpack.io") }
		}
	}

Add to pom.xml

	<repositories>
		<repository>
		    <id>jitpack.io</id>
		    <url>https://jitpack.io</url>
		</repository>
	</repositories>

Add it in your build.sbt at the end of resolvers:

 
    resolvers += "jitpack" at "https://jitpack.io"

Add it in your project.clj at the end of repositories:

 
    :repositories [["jitpack" "https://jitpack.io"]]

Step 2. Add the dependency

	dependencies {
		implementation 'com.github.OpenHFT:Java-Lang:v6.3.4'
	}

	dependencies {
		implementation("com.github.OpenHFT:Java-Lang:v6.3.4")
	}

	<dependency>
	    <groupId>com.github.OpenHFT</groupId>
	    <artifactId>Java-Lang</artifactId>
	    <version>v6.3.4</version>
	</dependency>


                            
    libraryDependencies += "com.github.OpenHFT" % "Java-Lang" % "v6.3.4"


                            
    :dependencies [[com.github.OpenHFT/Java-Lang "v6.3.4"]]

Readme

JavaLang

This project has been superseded by Chronicle-Core and Chronicle-Bytes project. Please consider migration!

This module provides marshalling, de-marshalling and handling of thread safe off heap memory through ByteBuffers.

This module is available on maven central as

<dependency>
    <groupId>net.openhft</groupId>
    <artifactId>lang</artifactId>
    <version><!--replace with the latest version--></version>
</dependency>

The version 6.x signifies that it is build for Java 6+. (It requires Java 6 update 18 or later to build)

JavaDoc

Check out our documentation at [JavaDoc] (http://openhft.github.io/Java-Lang/apidocs/)

Working with off heap objects.

Java-Lang 6.1 adds support for basic off heap data structures. More collections types and more complex data types will be added in future versions.

public interface DataType {
     // add getters and setters here
}

// can create an array of any size (provided you have the memory) off heap.
HugeArray<DataType> array = HugeCollections.newArray(DataType.class, 10*1000*1000*1000L);
DataType dt = array.get(1111111111);

// set data on dt
array.recycle(dt); // recycle the reference (or discard it)

// create a ring writeBuffer
HugeQueue<DataType> queue = HugeCollections.newQueue(DataType.class, 10*1000*1000L);
// give me a reference to an object to populate
DataType dt2 = queue.offer();
// set the values od dt2
queue.recycle(dt2);

DataType dt3 = queue.take();
// get values
queue.recycle(dt3);

This is designed to be largely GC-less and you can queue millions of entries with 32 MB heap and not trigger GCs.

Working with buffers

To work with buffers there is a several options:

ByteBufferBytes which wraps java.nio.ByteBuffer
DirectBytes which is slices/records of DirectStore - own implementation for offheap storage

Both classes provide functionality:

write\read operations for primitives (writeLong(long n), readLong() etc.)
locking in native memory, so you can add thread safe constructs to your native record.
CAS operations for int and long boolean compareAndSwapInt(long offset, int expected, int x), boolean compareAndSwapLong(long offset, long expected, long x)
addAndGetInt and getAndAddInt operations

Example

ByteBuffer byteBuffer = ByteBuffer.allocate(SIZE);
ByteBufferBytes bytes = new ByteBufferBytes(byteBuffer);
for (long i = 0; i < bytes.maximumLimit(); i++)
    bytes.writeLong(i);
for (long i = bytes.maximumLimit()-8; i >= 0; i -= 8) {
    int j = bytes.readLong(i);
    assert i ==  j;
}

Building for eclipse

Download Java-Lang zip from git https://github.com/OpenHFT/Java-Lang/archive/master.zip

Unzip master.zip, Java-Lang-master folder will be extracted from zip.

cd Java-Lang-master
mvn eclipse:eclipse

Now you have an eclipse project, import project into Eclipse

If your Eclipse configuration is not UTF-8, after importing the project you may see some errors and strange characters in some .java files. To get rid of this problem change character enconding to UTF-8: project->properties->resource->text file encoding->utf8