Overhauled "lock" functionality

src/Util/Lock.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Friendica\Util;
+
+/**
+ * @file src/Util/Lock.php
+ * @brief Functions for preventing parallel execution of functions
+ *
+ */
+
+use dba;
+use dbm;
+
+/**
+ * @brief This class contain Functions for preventing parallel execution of functions
+ */
+class Lock {
+
+
+// Provide some ability to lock a PHP function so that multiple processes
+// can't run the function concurrently
+
+	public static function set($fn_name, $wait_sec = 2, $timeout = 30) {
+		if ($wait_sec == 0) {
+			$wait_sec = 2;
+		}
+
+		$got_lock = false;
+		$start = time();
+
+		do {
+			dba:p("LOCK TABLE `locks` WRITE");
+			$lock = dba::select('locks', array('locked'), array('name' => $fn_name), array('limit' => 1));
+
+			if ((dbm::is_result($lock)) AND !$lock['locked']) {
+				dba::update('locks', array('locked' => true), array('name' => $fn_name));
+				$got_lock = true;
+			} elseif (!dbm::is_result($lock)) {
+				dbm::insert('locks', array('name' => $fn_name, 'locked' => true));
+				$got_lock = true;
+			}
+
+			dbm::p("UNLOCK TABLES");
+
+			if (!$got_lock) {
+				sleep($wait_sec);
+			}
+		} while (!$got_lock AND ((time() - $start) < $timeout));
+
+		logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
+
+		return $got_lock;
+	}
+
+	public static function remove($fn_name) {
+		dba::update('locks', array('locked' => false), array('name' => $fn_name));
+
+		logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
+
+		return;
+	}
+}