Add SAVEPOINT (Fixes #56)

lib/Pheasant/Database/Mysqli/Connection.php

@@ -5,6 +5,7 @@
 use Pheasant\Database\Dsn;
 use Pheasant\Database\FilterChain;
 use Pheasant\Database\MysqlPlatform;
+use Pheasant\Database\Mysqli\SavePointStack;
 
 /**
  * A connection to a MySql database
@@ -19,6 +20,8 @@ class Connection
         $_sequencePool,
         $_strict,
         $_selectedDatabase,
+        $_savePointStack,
+        $_events,
         $_debug=false
         ;
 
@@ -43,7 +46,45 @@ public function __construct(Dsn $dsn)
         if(!empty($this->_dsn->database))
             $this->_selectedDatabase = $this->_dsn->database;
 
+        $this->_events = new \Pheasant\Events();
         $this->_debug = getenv('PHEASANT_DEBUG');
+
+        // Setup a transaction stack
+        $this->_savePointStack = new SavePointStack();
+
+        // Keep a copy of ourselves around
+        $self = $this;
+
+        // The beforeTransaction event is where we will BEGIN or SAVEPOINT
+        $this->_events->register('beforeTransaction', function() use($self) {
+            // if `descend` returns null, there is nothing on the stack
+            // so we should BEGIN a transaction instead of a numbered SAVEPOINT.
+            $savepoint = $self->savePointStack()->descend();
+            $self->execute($savepoint === null ? "BEGIN" : "SAVEPOINT {$savepoint}");
+        });
+
+        // The afterTransaction replaces commitTransaction, and is where
+        // we will COMMIT or RELEASE
+        $this->_events->register('afterTransaction', function() use($self) {
+            // if `pop` returns null, then the stack is now empty
+            // so we should COMMIT instead of RELEASE.
+            $savepoint = $self->savePointStack()->pop();
+
+            // If the savepoint is null, then we are committing the
+            // transaction, and should fire the appropriate events.
+            $callback_name = $savepoint === null ? 'Commit' : 'SavePoint';
+            $self->events()->wrap($callback_name, $self, function($self) use($savepoint) {
+                $self->execute($savepoint === null ? "COMMIT" : "RELEASE SAVEPOINT {$savepoint}");
+            });
+        });
+
+        // The rollbackTransaction event is fired when we need to ROLLBACK
+        $this->_events->register('rollback', function() use($self) {
+            // if `pop` returns null, then the stack is now empty
+            // so we should ROLLBACK instead of ROLLBACK_TO.
+            $savepoint = $self->savePointStack()->pop();
+            $self->execute($savepoint === null ? "ROLLBACK" : "ROLLBACK TO {$savepoint}");
+        });
     }
 
     /**
@@ -248,4 +289,22 @@ public function selectedDatabase()
     {
         return $this->_selectedDatabase;
     }
+
+    /**
+     * Returns the Event object
+     * @return Event
+     */
+    public function events()
+    {
+        return $this->_events;
+    }
+
+    /**
+     * Returns the transaction stack
+     * @return SavePointStack
+     */
+    public function savePointStack()
+    {
+        return $this->_savePointStack;
+    }
 }

lib/Pheasant/Database/Mysqli/SavePointStack.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Pheasant\Database\Mysqli;
+
+/**
+ * A Transaction Stack that keeps track of open savepoints
+ */
+class SavePointStack
+{
+    private
+        $_savePointStack = array()
+        ;
+
+    /**
+     * Get the depth of the stack
+     * @return integer
+     */
+    public function depth()
+    {
+        return count($this->_savePointStack);
+    }
+
+    /**
+     * Decend deeper into the transaction stack and return a unique
+     * transaction savepoint name
+     * @return string
+     */
+    public function descend()
+    {
+        $this->_savePointStack[] = current($this->_savePointStack) === false
+            ? null
+            : 'savepoint_'.$this->depth();
+
+        return end($this->_savePointStack);
+    }
+
+    /**
+     * Pop off the last savepoint
+     * @return string
+     */
+    public function pop()
+    {
+      return array_pop($this->_savePointStack);
+    }
+}

lib/Pheasant/Database/Mysqli/Transaction.php

@@ -20,21 +20,19 @@ class Transaction
     public function __construct($connection=null)
     {
         $this->_connection = $connection ?: \Pheasant::instance()->connection();
-        $this->_events = new \Pheasant\Events();
+        $this->_events = new \Pheasant\Events(array(), $this->_connection->events());
     }
 
     public function execute()
     {
         $this->results = array();
 
         try {
-            $this->_connection->execute('BEGIN');
-            $this->_events->trigger('startTransaction', $this->_connection);
-            $this->_connection->execute('COMMIT');
-            $this->_events->trigger('commitTransaction', $this->_connection);
+            $this->_events->wrap('Transaction', $this, function($self) {
+              $self->events()->trigger('transaction', $self->connection());
+            });
         } catch (\Exception $e) {
-            $this->_connection->execute('ROLLBACK');
-            $this->_events->trigger('rollbackTransaction', $this->_connection);
+            $this->_events->trigger('rollback', $this->_connection);
             throw $e;
         }
 
@@ -51,7 +49,7 @@ public function callback($callback)
         $args = array_slice(func_get_args(),1);
 
         // use an event handler to dispatch to the callback
-        $this->_events->register('startTransaction', function($event, $connection) use ($t, $callback, $args) {
+        $this->_events->register('transaction', function($event, $connection) use ($t, $callback, $args) {
             $t->results []= call_user_func_array($callback, $args);
         });
 
@@ -67,23 +65,35 @@ public function events()
         return $this->_events;
     }
 
+    /**
+     * Get the connection object
+     * @return Connection
+     */
+    public function connection()
+    {
+        return $this->_connection;
+    }
+
     /**
      * Links another Events object such that events in it are corked until either commit/rollback and then uncorked
      * @chainable
      */
     public function deferEvents($events)
     {
         $this->_events
-            ->register('startTransaction', function() use ($events) {
+            ->registerOne('beforeTransaction', function() use ($events) {
                 $events->cork();
             })
-            ->register('commitTransaction', function() use ($events) {
-                $events->uncork();
-            })
-            ->register('rollbackTransaction', function() use ($events) {
+            ->registerOne('rollback', function() use ($events) {
                 $events->discard()->uncork();
             })
             ;
+
+        $this->connection()->events()->registerOne('afterCommit', function() use ($events) {
+                $events->uncork();
+            });
+
+        return $this;
     }
     /**
      * Creates a transaction and optionally execute a transaction

lib/Pheasant/Events.php

@@ -10,6 +10,7 @@ class Events
 {
     private
         $_handlers = array(),
+        $_oneHandlers = array(),
         $_queue = array(),
         $_corked = false,
         $_upstream
@@ -77,9 +78,18 @@ private function _callbacksFor($event)
     {
         $events = isset($this->_handlers[$event]) ? $this->_handlers[$event] : array();
 
+        if(isset($this->_oneHandlers[$event]))
+            $events = array_merge($events, $this->_oneHandlers[$event]);
+
+        if(isset($this->_oneHandlers['*']))
+            $events = array_merge($events, $this->_oneHandlers['*']);
+
         if(isset($this->_handlers['*']))
             $events = array_merge($events, $this->_handlers['*']);
 
+        // Clear the events that should only be run once
+        $this->_oneHandlers[$event] = array();
+
         return $events;
     }
 
@@ -94,6 +104,19 @@ public function register($event, $callback)
         return $this;
     }
 
+    /**
+     * Registers a handler for an event that is immediately removed
+     * after it is executed.
+     * @chainable
+     */
+    public function registerOne($event, $callback)
+    {
+        $this->_oneHandlers[$event][] = $callback;
+
+        return $this;
+    }
+
+
     /**
      * Unregisters an event handler based on event, or all
      * @chainable

tests/Pheasant/Tests/EventsTest.php

@@ -197,4 +197,19 @@ public function testSaveInAfterCreateDoesntLoop()
         $do->test = "blargh";
         $do->save();
     }
+
+    public function testRegisterOneEventBinding()
+    {
+        $fired = array();
+
+        $events = new Events();
+        $events->registerOne('fireOnceEvent', function() use(&$fired) {
+            $fired[] = 1;
+        });
+
+        $events->trigger('fireOnceEvent', new \stdClass());
+        $events->trigger('fireOnceEvent', new \stdClass());
+
+        $this->assertCount(1, $fired);
+    }
 }