traffic-shm (Shared Memory) is a Java based message library, which is designed for interprocess communication (IPC) on the same server.
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.
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+
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.
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.
offer a multi-producer/single-consumer concurrent data structure
Async Mode:
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();