traffic-shm

Overview

traffic-shm (Shared Memory) is a Java based message library, which is designed for interprocess communication (IPC) on the same server.

Features

1. Pure Java

Shared memory is an efficient mechanism for interprocess communication. Memory mapped files offer a dynamical memory management feature that allows applications to access files on disk in the same way they attach the shared segment of physical memory to their virtual address spaces.

traffic-shm provides a pure java implementation using sun.misc.Unsafe and FileChannel, JDK 1.6+ is required.

2. Cross-Platform

alignment: 4-bytes aligned byteorder: big-endian

Most of the major operating systems like Linux, macOS, Windows, AIX and HP-UX are supported.

Note:

• set -Xmpas:on on HP-UX
• set --add-opens=java.base/jdk.internal.misc=ALL-UNNAMED option to support JDK 9+

3. Async Mode:

3.1 Lock-Free

With non-blocking algorithm, implementation of multi-producer/single-consumer and multi-producer/multi-consumer concurrent queue, traffic-shm could be use to build a real-time system with high throughput and low latency.

3.2 Message Ordering

traffic-shm provides a FIFO queue which is ONCE-AND-ONLY-ONCE guaranteed. cursor is forward only, once a message is delivered successfully, message is AUTOMATIC ACKNOWLEDGEMENT which means that a message is acknowledged as soon as the receiver gets it.

4. Sync Mode:

4.1 Segmental Lock

offer a multi-producer/single-consumer concurrent data structure

Data Structure Layout

Async Mode:

Getting Started

Async:

Reader:

Queue queue = Queue.map("/Users/peptos/ashm", 2000L);;

while (running) {
	Block block = queue.poll();
	if (block != null) {
		System.out.println(new String(block.getPayload(), "UTF-8"));
	} else {
		Util.pause(10);
	}
}

queue.close();

Writer:

Queue queue = Queue.attach("/Users/peptos/ashm");

String string = "hello, world";
byte[] bytes = string.getBytes("UTF-8");
System.out.println(queue.offer(new Block(bytes)));

queue.close();