[WIP] Basic file streaming examples

.gitignore

@@ -1,2 +1,3 @@
+examples/file_stream_write.php.time
 vendor
 .phpunit.result.cache

examples/file_stream_read.php

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+<?php
+
+use React\Filesystem\Factory;
+use React\Filesystem\Node\FileInterface;
+use React\Stream\ReadableStreamInterface;
+use React\Stream\ThroughStream;
+
+require 'vendor/autoload.php';
+
+const READ_CHUNK_SIZE = 16; // Use 65536 for everything but this example
+
+function streamFile(FileInterface $file): ReadableStreamInterface
+{
+    $offset = 0;
+    $stream = new ThroughStream();
+
+    $read = function () use (&$read, $stream, &$offset, $file): void {
+        $file->getContents($offset, READ_CHUNK_SIZE)->then(
+            function (string $contents) use (&$read, $stream, &$offset, $file): void {
+                $length = strlen($contents);
+                if ($length === 0) {
+                    $stream->end('');
+                    return;
+                }
+                $offset += $length;
+                $stream->write($contents);
+                $read();
+            },
+            function (Throwable $throwable) use ($stream) {
+                $stream->emit('error', $throwable);
+                $stream->close();
+            }
+        );
+    };
+
+    $read();
+
+    return $stream;
+}
+
+Factory::create()->detect(__FILE__)->then(function (FileInterface $file) {
+    $stream = streamFile($file);
+    $stream->on('data', function (string $contents): void {
+        echo $contents;
+    });
+    $stream->on('error', function (Throwable $throwable): void {
+        echo $throwable;
+    });
+})->done();

examples/file_stream_write.php

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+<?php
+
+use React\EventLoop\Loop;
+use React\Filesystem\Factory;
+use React\Filesystem\Node\FileInterface;
+use React\Stream\ReadableStreamInterface;
+use React\Stream\ThroughStream;
+
+require 'vendor/autoload.php';
+
+function streamFile(FileInterface $file, ReadableStreamInterface $readableStream): void
+{
+    $buffer = '';
+    $writing = false;
+
+    $readableStream->on('data', function ($data) use (&$buffer, &$writing, $file): void {
+        $buffer .= $data;
+
+        if ($writing === false) {
+            $writing = true;
+            $writeData = $buffer;
+            $buffer = '';
+            $file->putContents($writeData, FILE_APPEND)->then(function (int $bytesWritten) use (&$buffer, &$writing, $writeData): void {
+                $writing = false;
+                $buffer = substr($writeData, $bytesWritten) . $buffer;
+            })->done();
+        }
+    });
+}
+
+file_put_contents(__FILE__ . '.time', '', FILE_APPEND);
+Factory::create()->detect(__FILE__ . '.time')->then(function (FileInterface $file) {
+    $stream = new ThroughStream();
+    streamFile($file, $stream);
+    for ($i = 0; $i < 13; $i++) {
+        Loop::addTimer($i, function () use ($stream): void {
+            $stream->write(time() . PHP_EOL);
+        });
+    }
+    Loop::addTimer(15, function () use ($stream): void {
+        $stream->end(time() . PHP_EOL);
+    });
+})->done();