update

README.md

@@ -3,6 +3,8 @@
 
 ### 局限性
 只能在同一台服务器内生效
+需要临时目录写入权限
+    (会在临时目录创建一个 _PHP_FileLock_xxx 类似的文件)
 
 ### Install
 
@@ -13,5 +15,15 @@ composer require sn01615/file-lock
 
 ```php
 use PhpUtils\FileLock;
-FileLock::lock('lockKey');
+
+# Get lock
+$status = FileLock::getLock('lockKey');
+if ($status) {
+    # Get lock success
+} else {
+    # It's locked.
+}
+
+# Unlock
+FileLock::unlock('lockKey');
 ```

src/FileLock.php

@@ -14,6 +14,16 @@ class FileLock
     private $lockFile;
 
     public static function lock($tag)
+    {
+        self::getLock($tag, true);
+    }
+
+    /**
+     * @param string $tag Unique identification
+     * @param bool $die Failed to acquire exclusive lock is whether to execute die()
+     * @return bool If get exclusive lock fail return false, else return true.
+     */
+    public static function getLock($tag, $die = null)
     {
         if (!self::$prefix) {
             self::$prefix = sys_get_temp_dir() . '/_PHP_FileLock_';
@@ -23,10 +33,12 @@ public static function lock($tag)
         file_put_contents($filename, time());
         self::$fp = fopen($filename, "r+");
         if (!flock(self::$fp, LOCK_EX | LOCK_NB)) {
-            die(0);
+            if ($die) die(0);
+            return false;
         }
         self::$instances[$tag] = new static();
         self::$instances[$tag]->lockFile = $filename;
+        return true;
     }
 
     public static function unlock($tag)