PHPLIB-413: Add support for read concerns in aggregations with an $out stage

Author: alcaeus

src/Collection.php

@@ -69,6 +69,7 @@ class Collection
     private static $wireVersionForFindAndModifyWriteConcern = 4;
     private static $wireVersionForReadConcern = 4;
     private static $wireVersionForWritableCommandWriteConcern = 5;
+    private static $wireVersionForReadConcernWithOutStage = 8;
 
     private $collectionName;
     private $databaseName;
@@ -201,15 +202,16 @@ public function aggregate(array $pipeline, array $options = [])
 
         $server = $this->manager->selectServer($options['readPreference']);
 
-        /* A "majority" read concern is not compatible with the $out stage, so
-         * avoid providing the Collection's read concern if it would conflict.
+        /* MongoDB 4.2 and later supports a read concern when an $out stage is
+         * being used, but earlier versions do not.
          *
          * A read concern is also not compatible with transactions.
          */
         if ( ! isset($options['readConcern']) &&
-            ! ($hasOutStage && $this->readConcern->getLevel() === ReadConcern::MAJORITY) &&
             \MongoDB\server_supports_feature($server, self::$wireVersionForReadConcern) &&
-            ! \MongoDB\is_in_transaction($options)) {
+            ! \MongoDB\is_in_transaction($options) &&
+            ( ! $hasOutStage || \MongoDB\server_supports_feature($server, self::$wireVersionForReadConcernWithOutStage))
+        ) {
             $options['readConcern'] = $this->readConcern;
         }
 

src/Database.php

@@ -48,6 +48,7 @@ class Database
     ];
     private static $wireVersionForReadConcern = 4;
     private static $wireVersionForWritableCommandWriteConcern = 5;
+    private static $wireVersionForReadConcernWithOutStage = 8;
 
     private $databaseName;
     private $manager;
@@ -186,15 +187,16 @@ public function aggregate(array $pipeline, array $options = [])
 
         $server = $this->manager->selectServer($options['readPreference']);
 
-        /* A "majority" read concern is not compatible with the $out stage, so
-         * avoid providing the Collection's read concern if it would conflict.
+        /* MongoDB 4.2 and later supports a read concern when an $out stage is
+         * being used, but earlier versions do not.
          *
          * A read concern is also not compatible with transactions.
          */
         if ( ! isset($options['readConcern']) &&
-            ! ($hasOutStage && $this->readConcern->getLevel() === ReadConcern::MAJORITY) &&
             \MongoDB\server_supports_feature($server, self::$wireVersionForReadConcern) &&
-            ! \MongoDB\is_in_transaction($options)) {
+            ! \MongoDB\is_in_transaction($options) &&
+            ( ! $hasOutStage || \MongoDB\server_supports_feature($server, self::$wireVersionForReadConcernWithOutStage))
+        ) {
             $options['readConcern'] = $this->readConcern;
         }
 

tests/SpecTests/Context.php

@@ -59,6 +59,10 @@ public static function fromCrud(stdClass $test, $databaseName, $collectionName)
 
         $clientOptions = isset($test->clientOptions) ? (array) $test->clientOptions : [];
 
+        if (isset($test->outcome->collection->name)) {
+            $o->outcomeCollectionName = $test->outcome->collection->name;
+        }
+
         $o->client = new Client(FunctionalTestCase::getUri(), $clientOptions);
 
         return $o;

tests/SpecTests/CrudSpecTest.php

@@ -19,11 +19,6 @@ class CrudSpecTest extends FunctionalTestCase
         'aggregate-merge: Aggregate with $merge and majority readConcern' => 'PHPLIB-438',
         'aggregate-merge: Aggregate with $merge and local readConcern' => 'PHPLIB-438',
         'aggregate-merge: Aggregate with $merge and available readConcern' => 'PHPLIB-438',
-        'aggregate-out-readConcern: readConcern majority with out stage' => 'PHPLIB-431',
-        'aggregate-out-readConcern: readConcern local with out stage' => 'PHPLIB-431',
-        'aggregate-out-readConcern: readConcern available with out stage' => 'PHPLIB-431',
-        'aggregate-out-readConcern: readConcern linearizable with out stage' => 'PHPLIB-431',
-        'aggregate-out-readConcern: invalid readConcern with out stage' => 'PHPLIB-431',
         'bulkWrite-arrayFilters: BulkWrite with arrayFilters' => 'Fails due to command assertions',
         'updateWithPipelines: UpdateOne using pipelines' => 'PHPLIB-418',
         'updateWithPipelines: UpdateMany using pipelines' => 'PHPLIB-418',