Async file reading and dns_lookup

examples/Async/dns_lookup.php

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+<?php
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+$ip = \Rx\Swoole\Async::dns_lookup('www.google.com');
+
+$ip->subscribe(
+    'print_r',
+    function (Throwable $throwable) {
+        echo "Error: " . $throwable->getMessage() . "\n";
+    },
+    function () {
+        echo "Completed.\n";
+    });

examples/Async/read.php

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+<?php
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+$file = \Rx\Swoole\Async::read(
+    __DIR__ . '/some_file.txt',
+    5);
+
+$file->subscribe(
+    'print_r',
+    function (Throwable $throwable) {
+        echo "Error: " . $throwable->getMessage() . "\n";
+    },
+    function () {
+        echo "Completed.\n";
+    });

examples/Async/some_file.txt

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+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

src/Async.php

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+<?php
+
+namespace Rx\Swoole;
+
+use Rx\Disposable\CallbackDisposable;
+use Rx\Disposable\EmptyDisposable;
+use Rx\Observable\AnonymousObservable;
+use Rx\ObserverInterface;
+
+final class Async
+{
+    public static function read(string $filename, int $size = 8192, int $offset = 0)
+    {
+        return new AnonymousObservable(function (ObserverInterface $observer) use ($filename, $size, $offset) {
+            $disposed = false;
+
+            $disposable = new CallbackDisposable(function () use (&$disposed) {
+                $disposed = true;
+            });
+
+            $callback = function ($filename, $data) use ($observer, &$disposed) {
+                if ($data === '') { // read complete
+                    $observer->onCompleted();
+                    return false;
+                }
+                if ($disposed) {
+                    return false;
+                }
+
+                $observer->onNext($data);
+                return true;
+            };
+
+            $retVal = \Swoole\Async::read($filename, $callback, $size, $offset);
+
+            if ($retVal === false) {
+                $observer->onError(new \Exception('Swoole\Asynd::read returned false'));
+                return;
+            }
+
+            return $disposable;
+        });
+    }
+
+    public static function dns_lookup($host)
+    {
+        return new AnonymousObservable(function (ObserverInterface $observer) use ($host) {
+            $callback = function ($host, $ip) use ($observer) {
+                if (empty($ip)) {
+                    $observer->onError(new \Exception('dns_lookup failed'));
+                }
+
+                $observer->onNext($ip);
+                $observer->onCompleted();
+            };
+
+            swoole_async_dns_lookup($host, $callback);
+
+            return new EmptyDisposable();
+        });
+    }
+}