atomic lock + last invoice id

src/Lock.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace OblioSoftware;
+
+class Lock {
+    protected $_path;
+    protected $_timeout = 30;
+    protected $_lockfileName = '.lockfile';
+    protected $_file;
+
+    public function __construct($path, $timeout = 30)
+    {
+        $this->_path = $path;
+        $this->_timeout = $timeout;
+        $this->_file = rtrim($this->_path, '/') . '/' . $this->_lockfileName;
+        $now = time();
+        while (file_exists($this->_file)) {
+            if (time() > $now + $timeout) {
+                return;
+            }
+            usleep(100000);
+        }
+        file_put_contents($this->_file, time());
+    }
+
+    public function __destruct()
+    {
+        $this->close();
+    }
+
+    public function close()
+    {
+        if (file_exists($this->_file)) {
+            unlink($this->_file);
+        }
+    }
+
+    public static function open()
+    {
+        return new self(WP_OBLIO_DIR);
+    } 
+}

view/components/order_details_invoice_box.php

@@ -36,8 +36,13 @@
 
     $order_meta_table = OblioSoftware\Order::get_meta_table_name();
     $field_name = OblioSoftware\Order::get_meta_table_field_name();
-    $sql = "SELECT {$field_name} FROM `{$order_meta_table}` WHERE meta_key='{$number_key}' AND meta_value<>'' ORDER BY `meta_value` DESC LIMIT 1";
-    $lastInvoice = $wpdb->get_var($sql);
+    $sql = "SELECT pmn.{$field_name} " . 
+		"FROM `{$order_meta_table}` pmn " . 
+		"JOIN `{$order_meta_table}` pms ON(pmn.post_id=pms.post_id AND pmn.meta_key='{$number_key}' AND pms.meta_key='{$series_name_key}') " . 
+		"WHERE pmn.meta_value<>'' AND pms.meta_value='{$series_name}' " . 
+		"ORDER BY pmn.`meta_value` DESC " . 
+		"LIMIT 1";
+    $lastInvoice = !$link ? null : $wpdb->get_var($sql);
     if ($link) {
         echo sprintf('<p><a class="button" href="%s" target="_blank">%s</a></p>',
             _wp_oblio_build_url('oblio-view-' . $options['docType'], $post), sprintf(__('Vezi %s %s %d', 'woocommerce-oblio'), $options['name'], $series_name, $number));