fjage and Fjage.jl startup stages don't agree

[ettersi]

The Fjåge MasterContainer sends out an "{\"alive\": true}" message once initialisation completed.

fjage/src/main/java/org/arl/fjage/remote/MasterContainer.java

Lines 347 to 352 in c53ff1d

	protected void initComplete() {
	synchronized(slaves) {
	for (ConnectionHandler slave: slaves) {
	if (!slave.isAlive()) slave.start();
	}
	}

fjage/src/main/java/org/arl/fjage/remote/ConnectionHandler.java

Lines 75 to 98 in c53ff1d

	public void run() {
	BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
	out = new DataOutputStream(conn.getOutputStream());
	if (keepAlive) {
	if (closeOnDead) {
	(new Thread(getName()+":init") {
	@Override
	public void run() {
	println(ALIVE);
	try {
	Thread.sleep(TIMEOUT);
	} catch (InterruptedException ex) {
	// do nothing
	}
	if (!alive) {
	log.fine("Connection dead");
	close();
	}
	}
	}).start();
	} else {
	println(ALIVE);
	}
	}

However, Container.send() only forwards messages after the container has started.

fjage/src/main/java/org/arl/fjage/remote/MasterContainer.java

Lines 220 to 221 in c53ff1d

	public boolean send(Message m, boolean relay) {
	if (!running) return false;

This is a problem because Fjage.jl interprets the "{\"alive\": true}" messages as a signal that the master container is now ready to accept messages.

https://github.com/org-arl/Fjage.jl/blob/b109126034cbdc517d8003e783df890677657002/src/gw.jl#L145-L148
https://github.com/org-arl/Fjage.jl/blob/b109126034cbdc517d8003e783df890677657002/src/container.jl#L468-L476

The result is that messages sent by slave-container agents may not reach their destination if these messages happen to fall in the gap between init() and start() on the master container.

Demonstration:

using Fjage

@agent struct Dummy; end
function Fjage.startup(agent::Dummy)
    node = agentforservice(agent, "org.arl.unet.Services.NODE_INFO")
    # Shouldn't trigger, but does
    @assert !isnothing(node.address)
end

simulator = run(`bin/unet samples/2-node-network.groovy`, wait = false)
try
    container = SlaveContainer("localhost", 1101, reconnect = false)
    add(container, Dummy())
    while true
        try
            start(container)
            break
        catch e
            sleep(0.01)
        end
    end
    sleep(3.0)
finally
    kill(simulator)
end