PHPLIB-618: Change estimatedDocumentCount to use $collStats (#811)

* PHPLIB-618: Change estimatedDocumentCount to use $collStats

* Address CR

* Fix checkstyle errors

Author: alcaeus

src/Operation/EstimatedDocumentCount.php

@@ -17,12 +17,18 @@
 
 namespace MongoDB\Operation;
 
+use MongoDB\Driver\Exception\CommandException;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
+use MongoDB\Driver\ReadConcern;
+use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnexpectedValueException;
 use MongoDB\Exception\UnsupportedException;
 use function array_intersect_key;
+use function is_integer;
+use function MongoDB\server_supports_feature;
 
 /**
  * Operation for obtaining an estimated count of documents in a collection
@@ -42,11 +48,15 @@ class EstimatedDocumentCount implements Executable, Explainable
     /** @var array */
     private $options;
 
-    /** @var Count */
-    private $count;
+    /** @var int */
+    private static $errorCodeCollectionNotFound = 26;
+
+    /** @var int */
+    private static $wireVersionForCollStats = 12;
 
     /**
-     * Constructs a count command.
+     * Constructs a command to get the estimated number of documents in a
+     * collection.
      *
      * Supported options:
      *
@@ -73,9 +83,24 @@ public function __construct($databaseName, $collectionName, array $options = [])
     {
         $this->databaseName = (string) $databaseName;
         $this->collectionName = (string) $collectionName;
-        $this->options = array_intersect_key($options, ['maxTimeMS' => 1, 'readConcern' => 1, 'readPreference' => 1, 'session' => 1]);
 
-        $this->count = $this->createCount();
+        if (isset($options['maxTimeMS']) && ! is_integer($options['maxTimeMS'])) {
+            throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
+        }
+
+        if (isset($options['readConcern']) && ! $options['readConcern'] instanceof ReadConcern) {
+            throw InvalidArgumentException::invalidType('"readConcern" option', $options['readConcern'], ReadConcern::class);
+        }
+
+        if (isset($options['readPreference']) && ! $options['readPreference'] instanceof ReadPreference) {
+            throw InvalidArgumentException::invalidType('"readPreference" option', $options['readPreference'], ReadPreference::class);
+        }
+
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], Session::class);
+        }
+
+        $this->options = array_intersect_key($options, ['maxTimeMS' => 1, 'readConcern' => 1, 'readPreference' => 1, 'session' => 1]);
     }
 
     /**
@@ -90,18 +115,54 @@ public function __construct($databaseName, $collectionName, array $options = [])
      */
     public function execute(Server $server)
     {
-        return $this->count->execute($server);
+        $command = $this->createCommand($server);
+
+        if ($command instanceof Aggregate) {
+            try {
+                $cursor = $command->execute($server);
+            } catch (CommandException $e) {
+                if ($e->getCode() == self::$errorCodeCollectionNotFound) {
+                    return 0;
+                }
+
+                throw $e;
+            }
+
+            $cursor->rewind();
+
+            return $cursor->current()->n;
+        }
+
+        return $command->execute($server);
     }
 
     public function getCommandDocument(Server $server)
     {
-        return $this->count->getCommandDocument($server);
+        return $this->createCommand($server)->getCommandDocument($server);
     }
 
-    /**
-     * @return Count
-     */
-    private function createCount()
+    private function createAggregate() : Aggregate
+    {
+        return new Aggregate(
+            $this->databaseName,
+            $this->collectionName,
+            [
+                ['$collStats' => ['count' => (object) []]],
+                ['$group' => ['_id' => 1, 'n' => ['$sum' => '$count']]],
+            ],
+            $this->options
+        );
+    }
+
+    /** @return Aggregate|Count */
+    private function createCommand(Server $server)
+    {
+        return server_supports_feature($server, self::$wireVersionForCollStats)
+            ? $this->createAggregate()
+            : $this->createCount();
+    }
+
+    private function createCount() : Count
     {
         return new Count($this->databaseName, $this->collectionName, [], $this->options);
     }

tests/FunctionalTestCase.php

@@ -32,6 +32,7 @@
 use function phpinfo;
 use function preg_match;
 use function preg_quote;
+use function preg_replace;
 use function sprintf;
 use function version_compare;
 use const INFO_MODULES;
@@ -278,7 +279,7 @@ protected function getServerVersion(ReadPreference $readPreference = null)
         $document = current($cursor->toArray());
 
         if (isset($document['version']) && is_string($document['version'])) {
-            return $document['version'];
+            return preg_replace('#^(\d+\.\d+\.\d+).*$#', '\1', $document['version']);
         }
 
         throw new UnexpectedValueException('Could not determine server version');

tests/SpecTests/ClientSideEncryptionSpecTest.php

@@ -395,8 +395,8 @@ function ($command) use (&$commands) {
                     }
                 );
 
-            $test->assertCount(2, $commands);
-        },
+                $test->assertCount(2, $commands);
+            },
         ];
 
         yield 'Test 4' => [
@@ -424,8 +424,8 @@ function ($command) use (&$commands) {
                     }
                 );
 
-            $test->assertCount(2, $commands);
-        },
+                $test->assertCount(2, $commands);
+            },
         ];
 
         yield 'Test 5' => [