Merge pull request #87 from clue-labs/lazy-connection

Add new createLazyConnection() method to only connect only on demand (on first command)

Author: WyriHaximus

README.md

@@ -15,6 +15,7 @@ It is written in pure PHP and does not require any extensions.
 * [Usage](#usage)
   * [Factory](#factory)
     * [createConnection()](#createconnection)
+    * [createLazyConnection()](#createlazyconnection)
   * [ConnectionInterface](#connectioninterface)
     * [query()](#query)
     * [queryStream()](#querystream)
@@ -35,20 +36,20 @@ $loop = React\EventLoop\Factory::create();
 $factory = new Factory($loop);
 
 $uri = 'test:test@localhost/test';
-$factory->createConnection($uri)->then(function (ConnectionInterface $connection) {
-    $connection->query('SELECT * FROM book')->then(
-        function (QueryResult $command) {
-            print_r($command->resultFields);
-            print_r($command->resultRows);
-            echo count($command->resultRows) . ' row(s) in set' . PHP_EOL;
-        },
-        function (Exception $error) {
-            echo 'Error: ' . $error->getMessage() . PHP_EOL;
-        }
-    );
-    
-    $connection->quit();
-});
+$connection = $factory->createLazyConnection($uri);
+
+$connection->query('SELECT * FROM book')->then(
+    function (QueryResult $command) {
+        print_r($command->resultFields);
+        print_r($command->resultRows);
+        echo count($command->resultRows) . ' row(s) in set' . PHP_EOL;
+    },
+    function (Exception $error) {
+        echo 'Error: ' . $error->getMessage() . PHP_EOL;
+    }
+);
+
+$connection->quit();
 
 $loop->run();
 ```
@@ -154,6 +155,76 @@ authentication. You can explicitly pass a custom timeout value in seconds
 $factory->createConnection('localhost?timeout=0.5');
 ```
 
+#### createLazyConnection()
+
+Creates a new connection.
+
+It helps with establishing a TCP/IP connection to your MySQL database
+and issuing the initial authentication handshake.
+
+```php
+$connection = $factory->createLazyConnection($url);
+
+$connection->query(…);
+```
+
+This method immediately returns a "virtual" connection implementing the
+[`ConnectionInterface`](#connectioninterface) that can be used to
+interface with your MySQL database. Internally, it lazily creates the
+underlying database connection (which may take some time) only once the
+first request is invoked on this instance and will queue all outstanding
+requests until the underlying connection is ready.
+
+From a consumer side this means that you can start sending queries to the
+database right away while the actual connection may still be outstanding.
+It will ensure that all commands will be executed in the order they are
+enqueued once the connection is ready. If the database connection fails,
+it will emit an `error` event, reject all outstanding commands and `close`
+the connection as described in the `ConnectionInterface`. In other words,
+it behaves just like a real connection and frees you from having to deal
+with its async resolution.
+
+Note that creating the underlying connection will be deferred until the
+first request is invoked. Accordingly, any eventual connection issues
+will be detected once this instance is first used. Similarly, calling
+`quit()` on this instance before invoking any requests will succeed
+immediately and will not wait for an actual underlying connection.
+
+Depending on your particular use case, you may prefer this method or the
+underlying `createConnection()` which resolves with a promise. For many
+simple use cases it may be easier to create a lazy connection.
+
+The `$url` parameter must contain the database host, optional
+authentication, port and database to connect to:
+
+```php
+$factory->createLazyConnection('user:secret@localhost:3306/database');
+```
+
+You can omit the port if you're connecting to default port `3306`:
+
+```php
+$factory->createLazyConnection('user:secret@localhost/database');
+```
+
+If you do not include authentication and/or database, then this method
+will default to trying to connect as user `root` with an empty password
+and no database selected. This may be useful when initially setting up a
+database, but likely to yield an authentication error in a production system:
+
+```php
+$factory->createLazyConnection('localhost');
+```
+
+This method respects PHP's `default_socket_timeout` setting (default 60s)
+as a timeout for establishing the underlying connection and waiting for
+successful authentication. You can explicitly pass a custom timeout value
+in seconds (or use a negative number to not apply a timeout) like this:
+
+```php
+$factory->createLazyConnection('localhost?timeout=0.5');
+```
+
 ### ConnectionInterface
 
 The `ConnectionInterface` represents a connection that is responsible for

composer.json

@@ -8,6 +8,7 @@
         "evenement/evenement": "^3.0 || ^2.1 || ^1.1",
         "react/event-loop": "^1.0 || ^0.5 || ^0.4",
         "react/promise": "^2.7",
+        "react/promise-stream": "^1.1",
         "react/promise-timer": "^1.5",
         "react/socket": "^1.1"
     },

examples/01-query.php

@@ -1,6 +1,5 @@
 <?php
 
-use React\MySQL\ConnectionInterface;
 use React\MySQL\Factory;
 use React\MySQL\QueryResult;
 
@@ -12,27 +11,27 @@
 $uri = 'test:test@localhost/test';
 $query = isset($argv[1]) ? $argv[1] : 'select * from book';
 
-//create a mysql connection for executing query
-$factory->createConnection($uri)->then(function (ConnectionInterface $connection) use ($query) {
-    $connection->query($query)->then(function (QueryResult $command) {
-        if (isset($command->resultRows)) {
-            // this is a response to a SELECT etc. with some rows (0+)
-            print_r($command->resultFields);
-            print_r($command->resultRows);
-            echo count($command->resultRows) . ' row(s) in set' . PHP_EOL;
-        } else {
-            // this is an OK message in response to an UPDATE etc.
-            if ($command->insertId !== 0) {
-                var_dump('last insert ID', $command->insertId);
-            }
-            echo 'Query OK, ' . $command->affectedRows . ' row(s) affected' . PHP_EOL;
+//create a lazy mysql connection for executing query
+$connection = $factory->createLazyConnection($uri);
+
+$connection->query($query)->then(function (QueryResult $command) {
+    if (isset($command->resultRows)) {
+        // this is a response to a SELECT etc. with some rows (0+)
+        print_r($command->resultFields);
+        print_r($command->resultRows);
+        echo count($command->resultRows) . ' row(s) in set' . PHP_EOL;
+    } else {
+        // this is an OK message in response to an UPDATE etc.
+        if ($command->insertId !== 0) {
+            var_dump('last insert ID', $command->insertId);
         }
-    }, function (Exception $error) {
-        // the query was not executed successfully
-        echo 'Error: ' . $error->getMessage() . PHP_EOL;
-    });
+        echo 'Query OK, ' . $command->affectedRows . ' row(s) affected' . PHP_EOL;
+    }
+}, function (Exception $error) {
+    // the query was not executed successfully
+    echo 'Error: ' . $error->getMessage() . PHP_EOL;
+});
 
-    $connection->quit();
-}, 'printf');
+$connection->quit();
 
 $loop->run();

examples/02-query-stream.php

@@ -2,7 +2,6 @@
 
 // $ php examples/02-query-stream.php "SHOW VARIABLES"
 
-use React\MySQL\ConnectionInterface;
 use React\MySQL\Factory;
 
 require __DIR__ . '/../vendor/autoload.php';
@@ -13,23 +12,23 @@
 $uri = 'test:test@localhost/test';
 $query = isset($argv[1]) ? $argv[1] : 'select * from book';
 
-//create a mysql connection for executing query
-$factory->createConnection($uri)->then(function (ConnectionInterface $connection) use ($query) {
-    $stream = $connection->queryStream($query);
+//create a lazy mysql connection for executing query
+$connection = $factory->createLazyConnection($uri);
 
-    $stream->on('data', function ($row) {
-        echo json_encode($row, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) . PHP_EOL;
-    });
+$stream = $connection->queryStream($query);
 
-    $stream->on('error', function (Exception $e) {
-        echo 'Error: ' . $e->getMessage() . PHP_EOL;
-    });
+$stream->on('data', function ($row) {
+    echo json_encode($row, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) . PHP_EOL;
+});
 
-    $stream->on('close', function () {
-        echo 'CLOSED' . PHP_EOL;
-    });
+$stream->on('error', function (Exception $e) {
+    echo 'Error: ' . $e->getMessage() . PHP_EOL;
+});
 
-    $connection->quit();
-}, 'printf');
+$stream->on('close', function () {
+    echo 'CLOSED' . PHP_EOL;
+});
+
+$connection->quit();
 
 $loop->run();

src/Factory.php

@@ -13,6 +13,7 @@
 use React\Socket\Connector;
 use React\Socket\ConnectorInterface;
 use React\Socket\ConnectionInterface;
+use React\MySQL\Io\LazyConnection;
 
 class Factory
 {
@@ -194,4 +195,81 @@ public function createConnection($uri)
             throw $e;
         });
     }
+
+    /**
+     * Creates a new connection.
+     *
+     * It helps with establishing a TCP/IP connection to your MySQL database
+     * and issuing the initial authentication handshake.
+     *
+     * ```php
+     * $connection = $factory->createLazyConnection($url);
+     *
+     * $connection->query(…);
+     * ```
+     *
+     * This method immediately returns a "virtual" connection implementing the
+     * [`ConnectionInterface`](#connectioninterface) that can be used to
+     * interface with your MySQL database. Internally, it lazily creates the
+     * underlying database connection (which may take some time) only once the
+     * first request is invoked on this instance and will queue all outstanding
+     * requests until the underlying connection is ready.
+     *
+     * From a consumer side this means that you can start sending queries to the
+     * database right away while the actual connection may still be outstanding.
+     * It will ensure that all commands will be executed in the order they are
+     * enqueued once the connection is ready. If the database connection fails,
+     * it will emit an `error` event, reject all outstanding commands and `close`
+     * the connection as described in the `ConnectionInterface`. In other words,
+     * it behaves just like a real connection and frees you from having to deal
+     * with its async resolution.
+     *
+     * Note that creating the underlying connection will be deferred until the
+     * first request is invoked. Accordingly, any eventual connection issues
+     * will be detected once this instance is first used. Similarly, calling
+     * `quit()` on this instance before invoking any requests will succeed
+     * immediately and will not wait for an actual underlying connection.
+     *
+     * Depending on your particular use case, you may prefer this method or the
+     * underlying `createConnection()` which resolves with a promise. For many
+     * simple use cases it may be easier to create a lazy connection.
+     *
+     * The `$url` parameter must contain the database host, optional
+     * authentication, port and database to connect to:
+     *
+     * ```php
+     * $factory->createLazyConnection('user:secret@localhost:3306/database');
+     * ```
+     *
+     * You can omit the port if you're connecting to default port `3306`:
+     *
+     * ```php
+     * $factory->createLazyConnection('user:secret@localhost/database');
+     * ```
+     *
+     * If you do not include authentication and/or database, then this method
+     * will default to trying to connect as user `root` with an empty password
+     * and no database selected. This may be useful when initially setting up a
+     * database, but likely to yield an authentication error in a production system:
+     *
+     * ```php
+     * $factory->createLazyConnection('localhost');
+     * ```
+     *
+     * This method respects PHP's `default_socket_timeout` setting (default 60s)
+     * as a timeout for establishing the underlying connection and waiting for
+     * successful authentication. You can explicitly pass a custom timeout value
+     * in seconds (or use a negative number to not apply a timeout) like this:
+     *
+     * ```php
+     * $factory->createLazyConnection('localhost?timeout=0.5');
+     * ```
+     *
+     * @param string $uri
+     * @return ConnectionInterface
+     */
+    public function createLazyConnection($uri)
+    {
+        return new LazyConnection($this, $uri);
+    }
 }