Initial commit

kirby/src/Cms/ContentLocks.php

@@ -0,0 +1,228 @@
+<?php
+
+namespace Kirby\Cms;
+
+use Kirby\Data\Data;
+use Kirby\Exception\Exception;
+use Kirby\Filesystem\F;
+
+/**
+ * Manages all content lock files
+ *
+ * @package   Kirby Cms
+ * @author    Nico Hoffmann <nico@getkirby.com>,
+ *            Lukas Bestle <lukas@getkirby.com>
+ * @link      https://getkirby.com
+ * @copyright Bastian Allgeier
+ * @license   https://getkirby.com/license
+ */
+class ContentLocks
+{
+    /**
+     * Data from the `.lock` files
+     * that have been read so far
+     * cached by `.lock` file path
+     *
+     * @var array
+     */
+    protected $data = [];
+
+    /**
+     * PHP file handles for all currently
+     * open `.lock` files
+     *
+     * @var array
+     */
+    protected $handles = [];
+
+    /**
+     * Closes the open file handles
+     *
+     * @codeCoverageIgnore
+     */
+    public function __destruct()
+    {
+        foreach ($this->handles as $file => $handle) {
+            $this->closeHandle($file);
+        }
+    }
+
+    /**
+     * Removes the file lock and closes the file handle
+     *
+     * @param string $file
+     * @return void
+     * @throws \Kirby\Exception\Exception
+     */
+    protected function closeHandle(string $file)
+    {
+        if (isset($this->handles[$file]) === false) {
+            return;
+        }
+
+        $handle = $this->handles[$file];
+        $result = flock($handle, LOCK_UN) && fclose($handle);
+
+        if ($result !== true) {
+            throw new Exception('Unexpected file system error.'); // @codeCoverageIgnore
+        }
+
+        unset($this->handles[$file]);
+    }
+
+    /**
+     * Returns the path to a model's lock file
+     *
+     * @param \Kirby\Cms\ModelWithContent $model
+     * @return string
+     */
+    public static function file(ModelWithContent $model): string
+    {
+        return $model->contentFileDirectory() . '/.lock';
+    }
+
+    /**
+     * Returns the lock/unlock data for the specified model
+     *
+     * @param \Kirby\Cms\ModelWithContent $model
+     * @return array
+     */
+    public function get(ModelWithContent $model): array
+    {
+        $file = static::file($model);
+        $id   = static::id($model);
+
+        // return from cache if file was already loaded
+        if (isset($this->data[$file]) === true) {
+            return $this->data[$file][$id] ?? [];
+        }
+
+        // first get a handle to ensure a file system lock
+        $handle = $this->handle($file);
+
+        if (is_resource($handle) === true) {
+            // read data from file
+            clearstatcache();
+            $filesize = filesize($file);
+
+            if ($filesize > 0) {
+                // always read the whole file
+                rewind($handle);
+                $string = fread($handle, $filesize);
+                $data   = Data::decode($string, 'yaml');
+            }
+        }
+
+        $this->data[$file] = $data ?? [];
+
+        return $this->data[$file][$id] ?? [];
+    }
+
+    /**
+     * Returns the file handle to a `.lock` file
+     *
+     * @param string $file
+     * @param bool $create Whether to create the file if it does not exist
+     * @return resource|null File handle
+     * @throws \Kirby\Exception\Exception
+     */
+    protected function handle(string $file, bool $create = false)
+    {
+        // check for an already open handle
+        if (isset($this->handles[$file]) === true) {
+            return $this->handles[$file];
+        }
+
+        // don't create a file if not requested
+        if (is_file($file) !== true && $create !== true) {
+            return null;
+        }
+
+        $handle = @fopen($file, 'c+b');
+        if (is_resource($handle) === false) {
+            throw new Exception('Lock file ' . $file . ' could not be opened.'); // @codeCoverageIgnore
+        }
+
+        // lock the lock file exclusively to prevent changes by other threads
+        $result = flock($handle, LOCK_EX);
+        if ($result !== true) {
+            throw new Exception('Unexpected file system error.'); // @codeCoverageIgnore
+        }
+
+        return $this->handles[$file] = $handle;
+    }
+
+    /**
+     * Returns model ID used as the key for the data array;
+     * prepended with a slash because the $site otherwise won't have an ID
+     *
+     * @param \Kirby\Cms\ModelWithContent $model
+     * @return string
+     */
+    public static function id(ModelWithContent $model): string
+    {
+        return '/' . $model->id();
+    }
+
+    /**
+     * Sets and writes the lock/unlock data for the specified model
+     *
+     * @param \Kirby\Cms\ModelWithContent $model
+     * @param array $data
+     * @return bool
+     * @throws \Kirby\Exception\Exception
+     */
+    public function set(ModelWithContent $model, array $data): bool
+    {
+        $file   = static::file($model);
+        $id     = static::id($model);
+        $handle = $this->handle($file, true);
+
+        $this->data[$file][$id] = $data;
+
+        // make sure to unset model id entries,
+        // if no lock data for the model exists
+        foreach ($this->data[$file] as $id => $data) {
+            // there is no data for that model whatsoever
+            if (
+                isset($data['lock']) === false &&
+                (isset($data['unlock']) === false ||
+                count($data['unlock']) === 0)
+            ) {
+                unset($this->data[$file][$id]);
+
+            // there is empty unlock data, but still lock data
+            } elseif (
+                isset($data['unlock']) === true &&
+                count($data['unlock']) === 0
+            ) {
+                unset($this->data[$file][$id]['unlock']);
+            }
+        }
+
+        // there is no data left in the file whatsoever, delete the file
+        if (count($this->data[$file]) === 0) {
+            unset($this->data[$file]);
+
+            // close the file handle, otherwise we can't delete it on Windows
+            $this->closeHandle($file);
+
+            return F::remove($file);
+        }
+
+        $yaml = Data::encode($this->data[$file], 'yaml');
+
+        // delete all file contents first
+        if (rewind($handle) !== true || ftruncate($handle, 0) !== true) {
+            throw new Exception('Could not write lock file ' . $file . '.'); // @codeCoverageIgnore
+        }
+
+        // write the new contents
+        $result = fwrite($handle, $yaml);
+        if (is_int($result) === false || $result === 0) {
+            throw new Exception('Could not write lock file ' . $file . '.'); // @codeCoverageIgnore
+        }
+
+        return true;
+    }
+}