Restore logging for cache operations

`AbstractCache` exposes the ability to set a logger. Default behavior
automatically passes the logger reference down to the cache, unless a
specific cache instance was provided.

src/Mustache/Cache/AbstractCache.php

@@ -0,0 +1,27 @@
+<?php
+
+abstract class Mustache_Cache_AbstractCache implements Mustache_Cache
+{
+    private $logger = null;
+
+    public function getLogger()
+    {
+        return $this->logger;
+    }
+
+    public function setLogger($logger = null)
+    {
+        if ($logger !== null && !($logger instanceof Mustache_Logger || is_a($logger, 'Psr\\Log\\LoggerInterface'))) {
+            throw new Mustache_Exception_InvalidArgumentException('Expected an instance of Mustache_Logger or Psr\\Log\\LoggerInterface.');
+        }
+
+        $this->logger = $logger;
+    }
+
+    protected function log($level, $message, array $context = array())
+    {
+        if (isset($this->logger)) {
+            $this->logger->log($level, $message, $context);
+        }
+    }
+}

src/Mustache/Cache/FilesystemCache.php

@@ -1,6 +1,6 @@
 <?php
 
-class Mustache_Cache_FilesystemCache implements Mustache_Cache
+class Mustache_Cache_FilesystemCache extends Mustache_Cache_AbstractCache
 {
     private $directory;
     private $fileMode;
@@ -26,6 +26,13 @@ class Mustache_Cache_FilesystemCache implements Mustache_Cache
     public function cache($key, $value)
     {
         $fileName = $this->getCacheFilename($key);
+
+        $this->log(
+            Mustache_Logger::DEBUG,
+            'Writing to template cache: "{fileName}"',
+            array('fileName' => $fileName)
+        );
+
         $this->writeFile($fileName, $value);
         $this->load($key);
     }
@@ -39,6 +46,12 @@ class Mustache_Cache_FilesystemCache implements Mustache_Cache
     {
         $dirName = dirname($fileName);
         if (!is_dir($dirName)) {
+            $this->log(
+                Mustache_Logger::INFO,
+                'Creating Mustache template cache directory: "{dirName}"',
+                array('dirName' => $dirName)
+            );
+
             @mkdir($dirName, 0777, true);
             if (!is_dir($dirName)) {
                 throw new Mustache_Exception_RuntimeException(sprintf('Failed to create cache directory "%s".', $dirName));
@@ -50,6 +63,13 @@ class Mustache_Cache_FilesystemCache implements Mustache_Cache
     private function writeFile($fileName, $value)
     {
         $dirName = $this->buildDirectoryForFilename($fileName);
+
+        $this->log(
+            Mustache_Logger::DEBUG,
+            'Caching compiled template to "{fileName}"',
+            array('fileName' => $fileName)
+        );
+
         $tempFile = tempnam($dirName, basename($fileName));
         if (false !== @file_put_contents($tempFile, $value)) {
             if (@rename($tempFile, $fileName)) {
@@ -58,6 +78,12 @@ class Mustache_Cache_FilesystemCache implements Mustache_Cache
 
                 return $fileName;
             }
+
+            $this->log(
+                Mustache_Logger::ERROR,
+                'Unable to rename Mustache temp cache file: "{tempName}" -> "{fileName}"',
+                array('tempName' => $tempFile, 'fileName' => $fileName)
+            );
         }
 
         throw new Mustache_Exception_RuntimeException(sprintf('Failed to write cache file "%s".', $fileName));

src/Mustache/Cache/NoopCache.php

@@ -1,6 +1,6 @@
 <?php
 
-class Mustache_Cache_NoopCache implements Mustache_Cache
+class Mustache_Cache_NoopCache extends Mustache_Cache_AbstractCache
 {
     public function load($key)
     {
@@ -9,6 +9,11 @@ class Mustache_Cache_NoopCache implements Mustache_Cache
 
     public function cache($key, $compiled)
     {
+        $this->log(
+            Mustache_Logger::WARNING,
+            'Template cache disabled, evaluating class at runtime',
+            array()
+        );
         eval("?>".$compiled);
     }
 }

src/Mustache/Engine.php

@@ -164,6 +164,10 @@ class Mustache_Engine
         if (isset($options['strict_callables'])) {
             $this->strictCallables = $options['strict_callables'];
         }
+
+        if (!isset($options['cache']) || is_string($options['cache'])) {
+            $this->getCache()->setLogger($this->getLogger());
+        }
     }
 
     /**
@@ -506,12 +510,6 @@ class Mustache_Engine
     {
         if (!isset($this->cache)) {
             $this->cache = new Mustache_Cache_NoopCache();
-
-            $this->log(
-                Mustache_Logger::WARNING,
-                'Template cache disabled',
-                array()
-            );
         }
 
         return $this->cache;

test/Mustache/Test/EngineTest.php

@@ -294,7 +294,7 @@ class Mustache_Test_EngineTest extends PHPUnit_Framework_TestCase
         $result = $mustache->render('{{ foo }}', array('foo' => 'FOO'));
         $this->assertEquals('FOO', $result);
 
-        $this->assertContains('WARNING: Template cache disabled', file_get_contents($name));
+        $this->assertContains('WARNING: Template cache disabled, evaluating', file_get_contents($name));
     }
 
     public function testLoggingIsNotTooAnnoying()