Unit tests and I/O bindings (#8)

* Added composer config, added IO/error tests using phpunit

* Added ApiGen doc comments

* Added test to ensure last_error is not set from loading up the CRT

lib/crt.php

@@ -1,35 +1,105 @@
 <?php
-require_once('preload.php');
 
+/**
+ * Wrapper for the FFI interface to the CRT. There only ever needs to be one of these.
+ * Creating an instance of any NativeResource will activate the CRT binding. User code
+ * should only need to create one of these if they are only accessing CRT:: functions.
+ */
 final class CRT {
     private static $ffi = null;
+    private static $refcount = 0;
+
     function __construct() {
         if (is_null(self::$ffi)) {
             try {
                 self::$ffi = FFI::cdef(file_get_contents(__DIR__ . "/api.h"), __DIR__ . "/libaws-crt-ffi.so");
+                self::init();
             } catch (Exception $e) {
-                echo 'Exception: ', $e->getMessage(), "\n";
+                echo 'Exception while initializing CRT via FFI: ', $e->getMessage(), "\n";
             }
         }
+        ++self::$refcount;
+    }
+
+    function __destruct() {
+        if (--self::$refcount == 0) {
+            self::clean_up();
+            self::$ffi = null;
+        }
     }
 
-    function init() {
+    private static function init() {
         return self::$ffi->aws_crt_init();
     }
 
-    function clean_up() {
+    private static function clean_up() {
         return self::$ffi->aws_crt_clean_up();
     }
 
-    function last_error() {
+    /**
+     * @return integer last error code reported within the CRT
+     */
+    public static function last_error() {
         return self::$ffi->aws_crt_last_error();
     }
 
-    function error_str($error) {
+    /**
+     * @param integer $error Error code from the CRT, usually delivered via callback or {@see last_error}
+     * @return string Human-readable description of the provided error code
+     */
+    public static function error_str($error) {
         return self::$ffi->aws_crt_error_str((int) $error);
     }
 
-    function error_name($error) {
+    /**
+     * @param integer $error Error code from the CRT, usually delivered via callback or {@see last_error}
+     * @return string Name/enum identifier for the provided error code
+     */
+    public static function error_name($error) {
         return self::$ffi->aws_crt_error_name((int) $error);
     }
+
+    function event_loop_group_new($options) {
+        return self::$ffi->aws_crt_event_loop_group_new($options->num_threads);
+    }
+
+    function event_loop_group_release($elg) {
+        return self::$ffi->aws_crt_event_loop_group_release($elg);
+    }
+}
+
+/**
+ * Base class for all native resources, tracks all outstanding resources
+ * and provides basic leak checking
+ */
+abstract class NativeResource {
+    protected static $crt = null;
+    protected static $resources = [];
+    protected $native = null;
+
+    function __construct() {
+        if (is_null(self::$crt)) {
+            try {
+                self::$crt = new CRT();
+            } catch (Exception $e) {
+                echo 'Exception while loading CRT: ', $e->getMessage(), "\n";
+            }
+        }
+
+        self::$resources[spl_object_hash($this)] = 1;
+    }
+
+    protected function acquire($handle) {
+        $this->native = $handle;
+    }
+
+    protected function release() {
+        $this->native = null;
+    }
+
+    function __destruct() {
+        // Should have been destroyed and released by derived resource
+        assert($this->native == null);
+        unset(self::$resources[spl_object_hash($this)]);
+    }
 }