conn: create from socket fd

This patch adds the ability to create Tarantool connection
using an existing socket fd.

Closes #304

Author: askalt

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Added
+- The ability to connect to the Tarantool using an existing socket fd (#304).
+
 ## 1.1.2 - 2023-09-20
 
 ### Fixed

tarantool/__init__.py

@@ -51,7 +51,7 @@
     __version__ = '0.0.0-dev'
 
 
-def connect(host="localhost", port=33013, user=None, password=None,
+def connect(host="localhost", port=33013, user=None, password=None, use_socket_fd=False,
             encoding=ENCODING_DEFAULT, transport=DEFAULT_TRANSPORT,
             ssl_key_file=DEFAULT_SSL_KEY_FILE,
             ssl_cert_file=DEFAULT_SSL_CERT_FILE,
@@ -69,6 +69,9 @@ def connect(host="localhost", port=33013, user=None, password=None,
     :param password: Refer to
         :paramref:`~tarantool.Connection.params.password`.
 
+    :param use_socket_fd: Refer to
+        :paramref:`~tarantool.Connection.params.use_socket_fd`.
+
     :param encoding: Refer to
         :paramref:`~tarantool.Connection.params.encoding`.
 
@@ -104,7 +107,8 @@ def connect(host="localhost", port=33013, user=None, password=None,
                       ssl_key_file=ssl_key_file,
                       ssl_cert_file=ssl_cert_file,
                       ssl_ca_file=ssl_ca_file,
-                      ssl_ciphers=ssl_ciphers)
+                      ssl_ciphers=ssl_ciphers,
+                      use_socket_fd=use_socket_fd)
 
 
 def connectmesh(addrs=({'host': 'localhost', 'port': 3301},), user=None,

tarantool/connection.py

@@ -595,6 +595,7 @@ class Connection(ConnectionInterface):
     """
 
     def __init__(self, host, port,
+                 use_socket_fd=False,
                  user=None,
                  password=None,
                  socket_timeout=SOCKET_TIMEOUT,
@@ -626,6 +627,9 @@ def __init__(self, host, port,
         :param port: Server port or Unix socket path.
         :type port: :obj:`int` or :obj:`str`
 
+        :param use_socket_fd: If ``True``, port is treated as socket fd.
+        :type use_socket_fd: :obj:`bool`, optional
+
         :param user: User name for authentication on the Tarantool
             server.
         :type user: :obj:`str` or :obj:`None`, optional
@@ -865,6 +869,7 @@ def __init__(self, host, port,
         self._server_features = None
         self.required_protocol_version = required_protocol_version
         self.required_features = copy(required_features)
+        self.use_socket_fd = use_socket_fd
 
         if connect_now:
             self.connect()
@@ -941,9 +946,13 @@ def connect_unix(self):
             self.connected = True
             if self._socket:
                 self._socket.close()
-            self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            if self.use_socket_fd:
+                # Use an existing fd to create a socket, take ownership.
+                self._socket = socket.socket(fileno=self.port)
+            else:
+                self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+                self._socket.connect(self.port)
             self._socket.settimeout(self.connection_timeout)
-            self._socket.connect(self.port)
             self._socket.settimeout(self.socket_timeout)
         except socket.error as exc:
             self.connected = False

test/suites/test_dml.py

@@ -1,6 +1,7 @@
 """
 This module tests basic data operations.
 """
+import socket
 # pylint: disable=missing-class-docstring,missing-function-docstring,protected-access,fixme,too-many-public-methods,duplicate-code
 
 import sys
@@ -430,6 +431,21 @@ def test_16_extra_error_info_fields(self):
         else:
             self.fail('Expected error')
 
+    def test_17_unix_socket_fd_connect(self):
+        if sys.platform.startswith("win"):
+            self.skipTest("Skip UNIX socket tests on Windows since it uses remote server")
+
+        # pylint: disable=E1101
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        sock.connect(self.sock_srv.args['primary'])
+
+        sock_con = tarantool.connect(self.sock_srv.host, sock.fileno(), use_socket_fd=True)
+        sock.detach()
+        try:
+            self.assertEqual(sock_con.ping(notime=True), "Success")
+        finally:
+            sock_con.close()
+
     @classmethod
     def tearDownClass(cls):
         cls.con.close()