Added FetchExceptionHandler interface.

Added Stateless- and ExponentialSleep FetchExceptionHandler implementations.
Changed FEH defacto type from callable to FetchExceptionHandler.

Author: Bilge

src/Connector/ConnectionContext.php

@@ -1,6 +1,8 @@
 <?php
 namespace ScriptFUSION\Porter\Connector;
 
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\FetchExceptionHandler;
+
 /**
  * Specifies runtime connection settings and provides utility methods.
  */
@@ -24,7 +26,7 @@ final class ConnectionContext
 
     private $maxFetchAttempts;
 
-    public function __construct($mustCache, callable $fetchExceptionHandler, $maxFetchAttempts)
+    public function __construct($mustCache, FetchExceptionHandler $fetchExceptionHandler, $maxFetchAttempts)
     {
         $this->mustCache = (bool)$mustCache;
         $this->fetchExceptionHandler = $fetchExceptionHandler;
@@ -50,11 +52,13 @@ public function mustCache()
      */
     public function retry(callable $callback)
     {
+        $userHandlerReset = false;
+
         return \ScriptFUSION\Retry\retry(
             $this->maxFetchAttempts,
             $callback,
-            function (\Exception $exception) {
-                // Throw exception if unrecoverable.
+            function (\Exception $exception) use (&$userHandlerReset) {
+                // Throw exception instead of retrying, if unrecoverable.
                 if (!$exception instanceof RecoverableConnectorException) {
                     throw $exception;
                 }
@@ -64,7 +68,12 @@ function (\Exception $exception) {
                     call_user_func($this->providerFetchExceptionHandler, $exception);
                 }
 
-                // TODO Clone exception handler to avoid persisting state between calls.
+                if (!$userHandlerReset) {
+                    $this->fetchExceptionHandler->reset();
+                    $userHandlerReset = true;
+                }
+
+                // TODO: Remove call_user_func calls when PHP 5 support dropped.
                 call_user_func($this->fetchExceptionHandler, $exception);
             }
         );

src/Connector/FetchExceptionHandler/ExponentialSleepFetchExceptionHandler.php

@@ -0,0 +1,22 @@
+<?php
+namespace ScriptFUSION\Porter\Connector\FetchExceptionHandler;
+
+use ScriptFUSION\Retry\ExceptionHandler\ExponentialBackoffExceptionHandler;
+
+/**
+ * Sleeps for an exponentially increasing series of delays specified in microseconds.
+ */
+class ExponentialSleepFetchExceptionHandler implements FetchExceptionHandler
+{
+    private $handler;
+
+    public function reset()
+    {
+        $this->handler = new ExponentialBackoffExceptionHandler;
+    }
+
+    public function __invoke(\Exception $exception)
+    {
+        call_user_func($this->handler, $exception);
+    }
+}

src/Connector/FetchExceptionHandler/FetchExceptionHandler.php

@@ -0,0 +1,9 @@
+<?php
+namespace ScriptFUSION\Porter\Connector\FetchExceptionHandler;
+
+interface FetchExceptionHandler
+{
+    public function reset();
+
+    public function __invoke(\Exception $exception);
+}

src/Connector/FetchExceptionHandler/StatelessFetchExceptionHandler.php

@@ -0,0 +1,25 @@
+<?php
+namespace ScriptFUSION\Porter\Connector\FetchExceptionHandler;
+
+/**
+ * Contains a stateless fetch exception handler that does not respond to reset() calls.
+ */
+final class StatelessFetchExceptionHandler implements FetchExceptionHandler
+{
+    private $handler;
+
+    public function __construct(callable $handler)
+    {
+        $this->handler = $handler;
+    }
+
+    public function reset()
+    {
+        // Intentionally empty.
+    }
+
+    public function __invoke(\Exception $exception)
+    {
+        call_user_func($this->handler, $exception);
+    }
+}

src/Specification/ImportSpecification.php

@@ -1,9 +1,10 @@
 <?php
 namespace ScriptFUSION\Porter\Specification;
 
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\ExponentialSleepFetchExceptionHandler;
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\FetchExceptionHandler;
 use ScriptFUSION\Porter\Provider\Resource\ProviderResource;
 use ScriptFUSION\Porter\Transform\Transformer;
-use ScriptFUSION\Retry\ExceptionHandler\ExponentialBackoffExceptionHandler;
 
 /**
  * Specifies which resource to import and how the data should be transformed.
@@ -237,21 +238,22 @@ final public function setMaxFetchAttempts($attempts)
     /**
      * Gets the exception handler invoked each time a fetch attempt fails.
      *
-     * @return callable Exception handler.
+     * @return FetchExceptionHandler Fetch exception handler.
      */
     final public function getFetchExceptionHandler()
     {
-        return $this->fetchExceptionHandler ?: $this->fetchExceptionHandler = new ExponentialBackoffExceptionHandler;
+        return $this->fetchExceptionHandler ?: $this->fetchExceptionHandler
+            = new ExponentialSleepFetchExceptionHandler;
     }
 
     /**
      * Sets the exception handler invoked each time a fetch attempt fails.
      *
-     * @param callable $fetchExceptionHandler Exception handler.
+     * @param FetchExceptionHandler $fetchExceptionHandler Fetch exception handler.
      *
      * @return $this
      */
-    final public function setFetchExceptionHandler(callable $fetchExceptionHandler)
+    final public function setFetchExceptionHandler(FetchExceptionHandler $fetchExceptionHandler)
     {
         $this->fetchExceptionHandler = $fetchExceptionHandler;
 

test/FixtureFactory.php

@@ -2,6 +2,7 @@
 namespace ScriptFUSIONTest;
 
 use ScriptFUSION\Porter\Connector\ConnectionContext;
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\StatelessFetchExceptionHandler;
 use ScriptFUSION\Porter\Specification\ImportSpecification;
 use ScriptFUSION\StaticClass;
 
@@ -25,9 +26,9 @@ public static function buildConnectionContext(
     ) {
         return new ConnectionContext(
             $cacheAdvice,
-            $fetchExceptionHandler ?: function () {
+            $fetchExceptionHandler ?: new StatelessFetchExceptionHandler(static function () {
                 // Intentionally empty.
-            },
+            }),
             $maxFetchAttempts
         );
     }

test/Integration/Porter/PorterTest.php

@@ -12,6 +12,8 @@
 use ScriptFUSION\Porter\Connector\ConnectionContext;
 use ScriptFUSION\Porter\Connector\Connector;
 use ScriptFUSION\Porter\Connector\ConnectorOptions;
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\FetchExceptionHandler;
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\StatelessFetchExceptionHandler;
 use ScriptFUSION\Porter\Connector\ImportConnector;
 use ScriptFUSION\Porter\Connector\RecoverableConnectorException;
 use ScriptFUSION\Porter\ImportException;
@@ -25,7 +27,6 @@
 use ScriptFUSION\Porter\Specification\StaticDataImportSpecification;
 use ScriptFUSION\Porter\Transform\FilterTransformer;
 use ScriptFUSION\Porter\Transform\Transformer;
-use ScriptFUSION\Retry\ExceptionHandler\ExponentialBackoffExceptionHandler;
 use ScriptFUSION\Retry\FailingTooHardException;
 use ScriptFUSIONTest\MockFactory;
 
@@ -286,15 +287,17 @@ public function testUnrecoverableException()
     }
 
     /**
-     * Tests that a when custom fetch exception handler is specified and the connector throws a recoverable exception
+     * Tests that when a custom fetch exception handler is specified and the connector throws a recoverable exception
      * type, the handler is called on each retry.
      */
     public function testCustomFetchExceptionHandler()
     {
         $this->specification->setFetchExceptionHandler(
-            \Mockery::mock(ExponentialBackoffExceptionHandler::class)
+            \Mockery::mock(FetchExceptionHandler::class)
+                ->shouldReceive('reset')
+                    ->once()
                 ->shouldReceive('__invoke')
-                ->times(ImportSpecification::DEFAULT_FETCH_ATTEMPTS - 1)
+                    ->times(ImportSpecification::DEFAULT_FETCH_ATTEMPTS - 1)
                 ->getMock()
         );
 
@@ -310,9 +313,9 @@ public function testCustomFetchExceptionHandler()
      */
     public function testCustomProviderFetchExceptionHandler()
     {
-        $this->specification->setFetchExceptionHandler(function () {
+        $this->specification->setFetchExceptionHandler(new StatelessFetchExceptionHandler(function () {
             throw new \LogicException('This exception must not be thrown!');
-        });
+        }));
 
         $this->arrangeConnectorException($connectorException =
             new RecoverableConnectorException('This exception is caught by the provider handler.'));

test/Unit/Porter/ImportSpecificationTest.php

@@ -1,11 +1,11 @@
 <?php
 namespace ScriptFUSIONTest\Unit\Porter;
 
+use ScriptFUSION\Porter\Connector\FetchExceptionHandler\FetchExceptionHandler;
 use ScriptFUSION\Porter\Provider\Resource\ProviderResource;
 use ScriptFUSION\Porter\Specification\DuplicateTransformerException;
 use ScriptFUSION\Porter\Specification\ImportSpecification;
 use ScriptFUSION\Porter\Transform\Transformer;
-use ScriptFUSIONTest\Stubs\Invokable;
 
 /**
  * @see ImportSpecification
@@ -30,7 +30,7 @@ public function testClone()
         $this->specification
             ->addTransformer(\Mockery::mock(Transformer::class))
             ->setContext($context = (object)[])
-            ->setFetchExceptionHandler($handler = new Invokable)
+            ->setFetchExceptionHandler($handler = \Mockery::mock(FetchExceptionHandler::class))
         ;
 
         $specification = clone $this->specification;
@@ -141,7 +141,7 @@ public function provideFetchAttempts()
     public function testExceptionHandler()
     {
         self::assertSame(
-            $handler = new Invokable,
+            $handler = \Mockery::mock(FetchExceptionHandler::class),
             $this->specification->setFetchExceptionHandler($handler)->getFetchExceptionHandler()
         );
     }