import org.zeromq.ZContext;
import org.zeromq.ZLoop;
import org.zeromq.ZLoop.IZLoopHandler;
import org.zeromq.ZMQ;
import org.zeromq.ZMQ.PollItem;
import org.zeromq.ZMQ.Socket;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
// Clone server - Model Five
public class clonesrv5
{
private ZContext ctx; // Context wrapper
private Map<String, kvmsg> kvmap; // Key-value store
private ZLoop loop; // zloop reactor
private int port; // Main port we're working on
private long sequence; // How many updates we're at
private Socket snapshot; // Handle snapshot requests
private Socket publisher; // Publish updates to clients
private Socket collector; // Collect updates from clients
// .split snapshot handler
// This is the reactor handler for the snapshot socket; it accepts
// just the ICANHAZ? request and replies with a state snapshot ending
// with a KTHXBAI message:
private static class Snapshots implements IZLoopHandler
{
@Override
public int handle(ZLoop loop, PollItem item, Object arg)
{
clonesrv5 srv = (clonesrv5) arg;
Socket socket = item.getSocket();
byte[] identity = socket.recv();
if (identity != null) {
// Request is in second frame of message
String request = socket.recvStr();
String subtree = null;
if (request.equals("ICANHAZ?")) {
subtree = socket.recvStr();
}
else
System.out.printf("E: bad request, aborting\n");
if (subtree != null) {
// Send state socket to client
for (Entry<String, kvmsg> entry: srv.kvmap.entrySet()) {
sendSingle(entry.getValue(), identity, subtree, socket);
}
// Now send END message with getSequence number
System.out.printf("I: sending shapshot=%d\n", srv.sequence);
socket.send(identity, ZMQ.SNDMORE);
kvmsg kvmsg = new kvmsg(srv.sequence);
kvmsg.setKey("KTHXBAI");
kvmsg.setBody(subtree.getBytes());
kvmsg.send(socket);
kvmsg.destroy();
}
}
return 0;
}
}
// .split collect updates
// We store each update with a new getSequence number, and if necessary, a
// time-to-live. We publish updates immediately on our publisher socket:
private static class Collector implements IZLoopHandler
{
@Override
public int handle(ZLoop loop, PollItem item, Object arg)
{
clonesrv5 srv = (clonesrv5) arg;
Socket socket = item.getSocket();
kvmsg msg = kvmsg.recv(socket);
if (msg != null) {
msg.setSequence(++srv.sequence);
msg.send(srv.publisher);
int ttl = Integer.parseInt(msg.getProp("ttl"));
if (ttl > 0)
msg.setProp("ttl",
"%d", System.currentTimeMillis() + ttl * 1000);
msg.store(srv.kvmap);
System.out.printf("I: publishing update=%d\n", srv.sequence);
}
return 0;
}
}
private static class FlushTTL implements IZLoopHandler
{
@Override
public int handle(ZLoop loop, PollItem item, Object arg)
{
clonesrv5 srv = (clonesrv5) arg;
if (srv.kvmap != null) {
for (kvmsg msg: new ArrayList<kvmsg>(srv.kvmap.values())) {
srv.flushSingle(msg);
}
}
return 0;
}
}
public clonesrv5 ()
{
port = 5556;
ctx = new ZContext();
kvmap = new HashMap<String, kvmsg>();
loop = new ZLoop();
loop.verbose(false);
// Set up our clone server sockets
snapshot = ctx.createSocket(ZMQ.ROUTER);
snapshot.bind(String.format("tcp://*:%d", port));
publisher = ctx.createSocket(ZMQ.PUB);
publisher.bind(String.format("tcp://*:%d", port + 1));
collector = ctx.createSocket(ZMQ.PULL);
collector.bind(String.format("tcp://*:%d", port + 2));
}
public void run()
{
// Register our handlers with reactor
PollItem poller = new PollItem(snapshot, ZMQ.Poller.POLLIN);
loop.addPoller(poller, new Snapshots(), this);
poller = new PollItem(collector, ZMQ.Poller.POLLIN);
loop.addPoller(poller, new Collector(), this);
loop.addTimer(1000, 0, new FlushTTL(), this);
loop.start();
loop.destroy();
ctx.destroy();
}
// We call this function for each getKey-value pair in our hash table
private static void sendSingle(kvmsg msg, byte[] identity, String subtree, Socket socket)
{
if (subtree.equals(msg.getKey())) {
socket.send (identity, // Choose recipient
ZMQ.SNDMORE);
msg.send(socket);
}
}
// .split flush ephemeral values
// At regular intervals, we flush ephemeral values that have expired. This
// could be slow on very large data sets:
// If getKey-value pair has expired, delete it and publish the
// fact to listening clients.
private void flushSingle(kvmsg msg)
{
long ttl = Long.parseLong(msg.getProp("ttl"));
if (ttl > 0 && System.currentTimeMillis() >= ttl) {
msg.setSequence(++sequence);
msg.setBody("".getBytes());
msg.send(publisher);
msg.store(kvmap);
System.out.printf("I: publishing delete=%d\n", sequence);
}
}
public static void main(String[] args)
{
clonesrv5 srv = new clonesrv5();
srv.run();
}
}