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)

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

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.

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

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; } 

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