nats.docs/_examples/drain_conn.html

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	<pre id="drain_conn_go_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/go-nats-examples/blob/master/api-examples/drain_conn/main.go#L12-64"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-go">wg := sync.WaitGroup{}
wg.Add(1)

errCh := make(chan error, 1)

// To simulate a timeout, you would set the DrainTimeout()
// to a value less than the time spent in the message callback,
// so say: nats.DrainTimeout(10*time.Millisecond).

nc, err := nats.Connect(&#34;demo.nats.io&#34;,
	nats.DrainTimeout(10*time.Second),
	nats.ErrorHandler(func(_ *nats.Conn, _ *nats.Subscription, err error) {
		errCh &lt;- err
	}),
	nats.ClosedHandler(func(_ *nats.Conn) {
		wg.Done()
	}))
if err != nil {
	log.Fatal(err)
}

// Just to not collide using the demo server with other users.
subject := nats.NewInbox()

// Subscribe, but add some delay while processing.
if _, err := nc.Subscribe(subject, func(_ *nats.Msg) {
	time.Sleep(200 * time.Millisecond)
}); err != nil {
	log.Fatal(err)
}

// Publish a message
if err := nc.Publish(subject, []byte(&#34;hello&#34;)); err != nil {
	log.Fatal(err)
}

// Drain the connection, which will close it when done.
if err := nc.Drain(); err != nil {
	log.Fatal(err)
}

// Wait for the connection to be closed.
wg.Wait()

// Check if there was an error
select {
case e := &lt;-errCh:
	log.Fatal(e)
default:
}

</code></pre>
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	<pre id="drain_conn_java_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/java-nats-examples/blob/master/src/main/java/io/nats/examples/DrainConn.java#L16-40"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-java">Connection nc = Nats.connect(&#34;nats://demo.nats.io:4222&#34;);

// Use a latch to wait for a message to arrive
CountDownLatch latch = new CountDownLatch(1);

// Create a dispatcher and inline message handler
Dispatcher d = nc.createDispatcher((msg) -&gt; {
    String str = new String(msg.getData(), StandardCharsets.UTF_8);
    System.out.println(str);
    latch.countDown();
});

// Subscribe
d.subscribe(&#34;updates&#34;);

// Wait for a message to come in
latch.await();

// Drain the connection, which will close it
CompletableFuture&lt;Boolean&gt; drained = nc.drain(Duration.ofSeconds(10));

// Wait for the drain to complete
drained.get();
</code></pre>
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	<pre id="drain_conn_js_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/node-nats-examples/blob/master/src/connection_samples.js#L91-111"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript">let nc = NATS.connect({url: &#34;nats://demo.nats.io:4222&#34;});
let inbox = createInbox();
let counter = 0;
nc.subscribe(inbox, () =&gt; {
    counter&#43;&#43;;
});

nc.publish(inbox);
nc.drain((err)=&gt; {
    if(err) {
        t.log(err);
    }
    t.log(&#39;connection is closed:&#39;, nc.closed);
    t.log(&#39;processed&#39;, counter, &#39;messages&#39;);
    t.pass();
    // the snippet is running as a promise in a test
    // and calls resolve to pass the test
    resolve();
});
</code></pre>
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	<pre id="drain_conn_py_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/asyncio-nats-examples/blob/master/drain_conn.py#L1-34"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-python">import asyncio
from nats.aio.client import Client as NATS

async def example(loop):
    nc = NATS()

    await nc.connect(&#34;nats://127.0.0.1:4222&#34;, loop=loop)

    async def handler(msg):
        print(&#34;[Received] &#34;, msg)
        await nc.publish(msg.reply, b&#39;I can help&#39;)

        # Can check whether client is in draining state
        if nc.is_draining:
            print(&#34;Connection is draining&#34;)

    await nc.subscribe(&#34;help&#34;, &#34;workers&#34;, cb=handler)
    await nc.flush()

    requests = []
    for i in range(0, 10):
        request = nc.request(&#34;help&#34;, b&#39;help!&#39;, timeout=1)
        requests.append(request)

    # Wait for all the responses
    responses = []
    responses = await asyncio.gather(*requests)

    # Gracefully close the connection.
    await nc.drain()

    print(&#34;Received {} responses&#34;.format(len(responses)))
</code></pre>
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	<pre id="drain_conn_ruby_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ruby-nats-examples/blob/master/drain_conn.rb#L3-26"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-ruby">NATS.start(drain_timeout: 1) do |nc|
  NATS.subscribe(&#39;foo&#39;, queue: &#34;workers&#34;) do |msg, reply, sub|
    nc.publish(reply, &#34;ACK:#{msg}&#34;)
  end

  NATS.subscribe(&#39;bar&#39;, queue: &#34;workers&#34;) do |msg, reply, sub|
    nc.publish(reply, &#34;ACK:#{msg}&#34;)
  end

  NATS.subscribe(&#39;quux&#39;, queue: &#34;workers&#34;) do |msg, reply, sub|
    nc.publish(reply, &#34;ACK:#{msg}&#34;)
  end

  EM.add_timer(2) do
    next if NATS.draining?

    # Drain gracefully closes the connection.
    NATS.drain do
      puts &#34;Done draining. Connection is closed.&#34;
    end
  end
end
</code></pre>
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	<pre id="drain_conn_ts_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ts-nats-examples/blob/master/src/connection_samples.ts#L73-83"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript">let sub = await nc.subscribe(&#39;updates&#39;, (err, msg) =&gt; {
    t.log(&#39;worker got message&#39;, msg.data);
}, {queue: &#34;workers&#34;});
// [end drain_sub]
nc.flush();

await nc.drain();
// client must close when the connection drain resolves
nc.close();
</code></pre>
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