Fix graceful shutdown

src/Client.php

@@ -7,6 +7,7 @@
 use Amp\Cancellation;
 use Amp\Future;
 use Amp\Pipeline;
+use Thesis\Nats\Exception\ConnectionWasClosed;
 use Thesis\Nats\Internal\Connection;
 use Thesis\Nats\Internal\Hooks;
 use Thesis\Nats\Internal\Id;
@@ -21,6 +22,7 @@
 use Thesis\Nats\Serialization\Serializer;
 use Thesis\Nats\Serialization\ValinorSerializer;
 use function Amp\async;
+use function Amp\weakClosure;
 
 /**
  * @api
@@ -331,36 +333,43 @@ private function disconnect(
             return;
         }
 
-        [$subscribers, $this->subscribers] = [$this->subscribers, []];
+        $completes = [];
 
-        /** @var ?Subscription $subscription */
-        foreach ($subscribers as [$_, $subscription]) {
+        foreach ($this->subscribers as [$_, $subscription]) {
             if ($subscription !== null) {
-                $do($subscription);
+                $completes[] = async($do, $subscription);
             }
         }
 
-        $this->rpc?->await($cancellation)?->shutdown($cancellation);
+        $rpc = $this->rpc?->await($cancellation);
 
-        $this->rpc = null;
-        $this->connection = null;
-        $connection->close();
+        if ($rpc !== null) {
+            $completes[] = async($rpc->shutdown(...), $cancellation);
+        }
+
+        try {
+            Future\await($completes, $cancellation);
+        } finally {
+            $this->subscribers = [];
+            $this->rpc = null;
+            $this->connection = null;
+            $connection->close();
+        }
     }
 
     private function connection(?Cancellation $cancellation = null): Connection\Connection
     {
-        $connectionFactory = $this->connectionFactory;
-        $invokeSubscriber = $this->invokeSubscriber(...);
+        $this->connection ??= async(weakClosure(function () use ($cancellation): Connection\Connection {
+            $connection = $this->connectionFactory->connect();
+            $connection->hooks()->onMessage($this->invokeSubscriber(...));
+            $connection->hooks()->onClose(function () use ($cancellation): void {
+                $e = new ConnectionWasClosed();
 
-        $this->connection ??= async(static function () use (
-            $connectionFactory,
-            $invokeSubscriber,
-        ): Connection\Connection {
-            $connection = $connectionFactory->connect();
-            $connection->hooks()->onMessage($invokeSubscriber);
+                $this->disconnect(static fn(Subscription $subscription) => $subscription->error($e, $cancellation));
+            });
 
             return $connection;
-        });
+        }));
 
         return $this->connection->await($cancellation);
     }

src/Internal/Connection/ConnectionState.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Nats\Internal\Connection;
+
+/**
+ * @internal
+ */
+enum ConnectionState
+{
+    case Idle;
+    case Alive;
+    case Closed;
+    case GracefulClosed;
+}

src/Internal/Connection/SocketConnection.php

@@ -32,7 +32,7 @@ final class SocketConnection implements Connection
 
     private ?ConnectionInfo $info = null;
 
-    private bool $running = false;
+    private ConnectionState $state = ConnectionState::Idle;
 
     private readonly Signer $signer;
 
@@ -63,7 +63,7 @@ public function startup(): void
             );
         }
 
-        if (!$this->running) {
+        if ($this->state !== ConnectionState::Alive) {
             $this->run();
         }
 
@@ -124,8 +124,7 @@ public function info(): ConnectionInfo
     public function close(): void
     {
         $this->hooks->dispatch(Hooks\ConnectionClosed::Event);
-
-        $this->running = false;
+        $this->state = ConnectionState::GracefulClosed;
         $this->socket->close();
     }
 
@@ -134,15 +133,17 @@ private function run(): void
         $framer = $this->framer;
         $queue = $this->queue;
         $hooks = $this->hooks;
-        $running = &$this->running;
+        $socket = $this->socket;
+        $state = &$this->state;
 
         EventLoop::queue(static function () use (
             $framer,
             $queue,
             $hooks,
-            &$running,
+            $socket,
+            &$state,
         ): void {
-            while ($running) {
+            while ($state === ConnectionState::Alive) {
                 try {
                     while (($frame = $framer->readFrame()) !== null) {
                         $event = match (true) {
@@ -170,28 +171,27 @@ private function run(): void
                         $deferred->error($e);
                     }
                 } finally {
-                    $running = false;
-                    $hooks->dispatch(Hooks\ConnectionClosed::Event);
+                    if ($state !== ConnectionState::GracefulClosed) { // @phpstan-ignore notIdentical.alwaysTrue
+                        $state = ConnectionState::Closed;
+                        $socket->close();
+                        $hooks->dispatch(Hooks\ConnectionClosed::Event);
+                    }
                 }
             }
         });
 
-        $this->running = true;
+        $this->state = ConnectionState::Alive;
     }
 
     /**
      * @throws \Exception
      */
     private function generateSignature(?string $nonce, ?string $nkey): ?string
     {
-        if ($nonce === null) {
-            return null;
-        }
-
-        if ($nkey === null) {
-            return null;
+        if ($nonce !== null && $nkey !== null) {
+            return $this->signer->sign($nonce, $nkey);
         }
 
-        return $this->signer->sign($nonce, $nkey);
+        return null;
     }
 }