Use atomic cache writing. (#1186)

Create a temp file, write the content and finally rename the file to the destination.
Because several concurrent processes accessing the cache are running into an error.

CHANGELOG.md

@@ -4,6 +4,7 @@ mPDF 8.1.x
 * Add Page Number Myanmar Language Support
 * new `Mpdf\Exception\FontException` extending base `MpdfException` was introduced and is thrown on Font manipulation
 * A bit cleaner exception messages for font-related errors
+* Use atomicity cache writing. Create a temp file, write the content and finally rename the file to the destination.
 
 mPDF 8.0.x
 ===========================

src/Cache.php

@@ -70,9 +70,11 @@ public function load($filename)
 
 	public function write($filename, $data)
 	{
-		$path = $this->getFilePath($filename);
+		$tempFile = tempnam($this->basePath, 'cache_tmp_');
+		file_put_contents($tempFile, $data);
 
-		file_put_contents($path, $data);
+		$path = $this->getFilePath($filename);
+		rename($tempFile, $path);
 
 		return $path;
 	}

src/Fonts/FontCache.php

@@ -53,9 +53,7 @@ public function write($filename, $data)
 
 	public function binaryWrite($filename, $data)
 	{
-		$handle = fopen($this->tempFilename($filename), 'wb');
-		fwrite($handle, $data);
-		fclose($handle);
+		return $this->cache->write($filename, $data);
 	}
 
 	public function jsonWrite($filename, $data)