public void launch()

in software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/cassandra/CassandraNodeSshDriver.java [232:322]
77 lines of code
17 McCabe index (conditional complexity)

    public void launch() {
        String subnetHostname = Machines.findSubnetOrPublicHostname(entity).get();
        Set<Entity> seeds = getEntity().getConfig(CassandraNode.INITIAL_SEEDS);
        List<Entity> ancestors = getCassandraAncestors();
        log.info("Launching " + entity + ": " +
                "cluster "+getClusterName()+", " +
                "hostname (public) " + getEntity().getAttribute(Attributes.HOSTNAME) + ", " +
                "hostname (subnet) " + subnetHostname + ", " +
                "seeds "+((CassandraNode)entity).getSeeds()+" (from "+seeds+")");

        boolean isFirst = seeds.iterator().next().equals(entity);
        if (isClustered() && !isFirst && CassandraDatacenter.WAIT_FOR_FIRST) {
            // wait for the first node
            long firstStartTime = Entities.submit(entity, DependentConfiguration.attributeWhenReady(
                ancestors.get(ancestors.size()-1), CassandraDatacenter.FIRST_NODE_STARTED_TIME_UTC)).getUnchecked();
            // optionally force a delay before starting subsequent nodes; see comment at CassandraCluster.DELAY_AFTER_FIRST
            Duration toWait = Duration.millis(firstStartTime + CassandraDatacenter.DELAY_AFTER_FIRST.toMilliseconds() -  System.currentTimeMillis());
            if (toWait.toMilliseconds()>0) {
                log.info("Launching " + entity + ": delaying launch of non-first node by "+toWait+" to prevent schema disagreements");
                Tasks.setBlockingDetails("Pausing to ensure first node has time to start");
                Time.sleep(toWait);
                Tasks.resetBlockingDetails();
            }
        }

        List<Entity> queuedStart = null;
        if (CassandraDatacenter.DELAY_BETWEEN_STARTS!=null && !ancestors.isEmpty()) {
            Entity root = ancestors.get(ancestors.size()-1);
            // TODO currently use the class as a semaphore; messy, and obviously will not federate;
            // should develop a brooklyn framework semaphore (similar to that done on SshMachineLocation)
            // and use it - note however the synch block is very very short so relatively safe at least
            synchronized (CassandraNode.class) {
                queuedStart = root.getAttribute(CassandraDatacenter.QUEUED_START_NODES);
                if (queuedStart==null) {
                    queuedStart = new ArrayList<Entity>();
                    root.sensors().set(CassandraDatacenter.QUEUED_START_NODES, queuedStart);
                }
                queuedStart.add(getEntity());
                root.sensors().set(CassandraDatacenter.QUEUED_START_NODES, queuedStart);
            }
            do {
                // get it again in case it is backed by something external
                queuedStart = root.getAttribute(CassandraDatacenter.QUEUED_START_NODES);
                if (queuedStart.get(0).equals(getEntity())) break;
                synchronized (queuedStart) {
                    try {
                        queuedStart.wait(1000);
                    } catch (InterruptedException e) {
                        Exceptions.propagate(e);
                    }
                }
            } while (true);

            // TODO should look at last start time... but instead we always wait
            CassandraDatacenter.DELAY_BETWEEN_STARTS.countdownTimer().waitForExpiryUnchecked();
        }

        try {
            // Relies on `bin/cassandra -p <pidfile>`, rather than us writing pid file ourselves.
            newScript(MutableMap.of(USE_PID_FILE, false), LAUNCHING)
                    .body.append(
                            // log the date to attempt to debug occasional http://wiki.apache.org/cassandra/FAQ#schema_disagreement
                            // (can be caused by machines out of synch time-wise; but in our case it seems to be caused by other things!)
                            "echo date on cassandra server `hostname` when launching is `date`",
                            launchEssentialCommand(),
                            "echo after essential command")
                    .execute();
            if (!isClustered()) {
                InputStream creationScript = DatastoreMixins.getDatabaseCreationScript(entity);
                if (creationScript!=null) {
                    Tasks.setBlockingDetails("Pausing to ensure Cassandra (singleton) has started before running creation script");
                    Time.sleep(Duration.seconds(20));
                    Tasks.resetBlockingDetails();
                    executeScriptAsync(Streams.readFullyStringAndClose(creationScript));
                }
            }
            if (isClustered() && isFirst) {
                for (Entity ancestor: getCassandraAncestors()) {
                    ancestor.sensors().set(CassandraDatacenter.FIRST_NODE_STARTED_TIME_UTC, System.currentTimeMillis());
                }
            }
        } finally {
            if (queuedStart!=null) {
                Entity head = queuedStart.remove(0);
                checkArgument(head.equals(getEntity()), "first queued node was "+head+" but we are "+getEntity());
                synchronized (queuedStart) {
                    queuedStart.notifyAll();
                }
            }
        }
    }