[5.2] Stabilized table aliases for self joins by adding count (#13401)

* stabilized table aliases for self joins by adding count, in order to improve query cacheability

* style fixes

* changed prefix to laravel_reserved_ for self join alias

src/Illuminate/Database/Eloquent/Relations/BelongsTo.php

@@ -30,6 +30,13 @@ class BelongsTo extends Relation
      */
     protected $relation;
 
+    /**
+     * The count of self joins.
+     *
+     * @var int
+     */
+    protected static $selfJoinCount = 0;
+
     /**
      * Create a new belongs to relationship instance.
      *
@@ -125,7 +132,7 @@ public function getRelationQueryForSelfRelation(Builder $query, Builder $parent,
      */
     public function getRelationCountHash()
     {
-        return 'self_'.md5(microtime(true));
+        return 'laravel_reserved_'.static::$selfJoinCount++;
     }
 
     /**

src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php

@@ -67,6 +67,13 @@ class BelongsToMany extends Relation
      */
     protected $pivotUpdatedAt;
 
+    /**
+     * The count of self joins.
+     *
+     * @var int
+     */
+    protected static $selfJoinCount = 0;
+
     /**
      * Create a new belongs to many relationship instance.
      *
@@ -376,7 +383,7 @@ public function getRelationQueryForSelfJoin(Builder $query, Builder $parent, $co
      */
     public function getRelationCountHash()
     {
-        return 'self_'.md5(microtime(true));
+        return 'laravel_reserved_'.static::$selfJoinCount++;
     }
 
     /**

src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php

@@ -23,6 +23,13 @@ abstract class HasOneOrMany extends Relation
      */
     protected $localKey;
 
+    /**
+     * The count of self joins.
+     *
+     * @var int
+     */
+    protected static $selfJoinCount = 0;
+
     /**
      * Create a new has one or many relationship instance.
      *
@@ -99,7 +106,7 @@ public function getRelationQueryForSelfRelation(Builder $query, Builder $parent,
      */
     public function getRelationCountHash()
     {
-        return 'self_'.md5(microtime(true));
+        return 'laravel_reserved_'.static::$selfJoinCount++;
     }
 
     /**

tests/Database/DatabaseEloquentBuilderTest.php

@@ -553,7 +553,7 @@ public function testSelfHasNested()
 
         // alias has a dynamic hash, so replace with a static string for comparison
         $alias = 'self_alias_hash';
-        $aliasRegex = '/\b(self_[a-f0-9]{32})(\b|$)/i';
+        $aliasRegex = '/\b(laravel_reserved_\d)(\b|$)/i';
 
         $nestedSql = preg_replace($aliasRegex, $alias, $nestedSql);
         $dotSql = preg_replace($aliasRegex, $alias, $dotSql);
@@ -569,7 +569,7 @@ public function testSelfHasNestedUsesAlias()
 
         // alias has a dynamic hash, so replace with a static string for comparison
         $alias = 'self_alias_hash';
-        $aliasRegex = '/\b(self_[a-f0-9]{32})(\b|$)/i';
+        $aliasRegex = '/\b(laravel_reserved_\d)(\b|$)/i';
 
         $sql = preg_replace($aliasRegex, $alias, $sql);