From a76cac78402df7ad01841c93fb64b02af4700b07 Mon Sep 17 00:00:00 2001
From: Vendula Poncova <vponcova@redhat.com>
Date: Thu, 9 Jun 2022 15:41:08 +0200
Subject: [PATCH] Raise TimeoutError if a DBus call times out

* Raise the TimeoutError exception instead of the original GLib.Error.
* Improve the documentation of the timeout and add an example.
---
 dasbus/client/handler.py | 49 ++++++++++++++++++++++++++++------------
 docs/examples.rst        | 11 +++++++++
 tests/test_client.py     | 18 ++++++++++++++-
 tests/test_dbus.py       | 21 +++++++++++++++++
 4 files changed, 84 insertions(+), 15 deletions(-)

diff --git a/dasbus/client/handler.py b/dasbus/client/handler.py
index 839f5a6..43b22f6 100644
--- a/dasbus/client/handler.py
+++ b/dasbus/client/handler.py
@@ -137,6 +137,12 @@ class GLibClient(object):
         """Unsubscribe from a signal."""
         connection.signal_unsubscribe(subscription_id)
 
+    @classmethod
+    def is_timeout_error(cls, error):
+        """Is it a timeout error?"""
+        return isinstance(error, GLib.Error) \
+            and error.matches(Gio.io_error_quark(), Gio.IOErrorEnum.TIMED_OUT)
+
     @classmethod
     def is_remote_error(cls, error):
         """Is it a remote DBus error?"""
@@ -479,22 +485,37 @@ class ClientObjectHandler(AbstractClientObjectHandler):
     def _handle_method_error(self, error):
         """Handle an error of a DBus call.
 
+        If the call returned a DBus error, it will be mapped
+        to a Python exception based on the rules defined in
+        the available error mapper. It should be a subclass
+        of DBusError.
+
         :param error: an exception raised during the call
+        :raise Exception: if the call unexpectedly failed
+        :raise TimeoutError: if the DBus call timed out
+        :raise DBusError: if the call returned a DBus error
         """
-        # Re-raise if it is not a remote DBus error.
-        if not self._client.is_remote_error(error):
-            raise error
-
-        name = self._client.get_remote_error_name(error)
-        cls = self._error_mapper.get_exception_type(name)
-        message = self._client.get_remote_error_message(error)
-
-        # Create a new exception.
-        exception = cls(message)
-        exception.dbus_name = name
-
-        # Raise a new instance of the exception class.
-        raise exception from None
+        if self._client.is_remote_error(error):
+            # Handle a remote DBus error.
+            name = self._client.get_remote_error_name(error)
+            cls = self._error_mapper.get_exception_type(name)
+            message = self._client.get_remote_error_message(error)
+
+            # Create a new exception.
+            exception = cls(message)
+            exception.dbus_name = name
+
+            # Raise a new instance of the exception class.
+            raise exception from None
+
+        if self._client.is_timeout_error(error):
+            # Handle a timeout error.
+            raise TimeoutError(
+                "The DBus call timeout was reached."
+            ) from None
+
+        # Or re-raise the original error.
+        raise error
 
     def _handle_method_result(self, result):
         """Handle a result of a DBus call.
diff --git a/docs/examples.rst b/docs/examples.rst
index 8d272a8..176c0b4 100644
--- a/docs/examples.rst
+++ b/docs/examples.rst
@@ -129,6 +129,17 @@ mapper to transform Python exceptions to DBus errors and back.
     class InvalidArgs(DBusError):
         pass
 
+Call DBus methods with a timeout (specified in milliseconds).
+
+.. code-block:: python
+
+    proxy = NETWORK_MANAGER.get_proxy()
+
+    try:
+        proxy.CheckConnectivity(timeout=3)
+    except TimeoutError:
+        print("The call timed out!")
+
 Call DBus methods asynchronously.
 
 .. code-block:: python
diff --git a/tests/test_client.py b/tests/test_client.py
index 03890ea..dcbdbb9 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -30,7 +30,8 @@ from dasbus.typing import get_variant, get_variant_type, VariantType
 
 import gi
 gi.require_version("Gio", "2.0")
-from gi.repository import Gio
+gi.require_version("GLib", "2.0")
+from gi.repository import Gio, GLib
 
 
 class FakeException(Exception):
@@ -230,6 +231,21 @@ class DBusClientTestCase(unittest.TestCase):
 
         self.assertEqual(str(cm.exception), "My message.")
 
+        # Handle timeout exception.
+        self._set_reply(GLib.Error.new_literal(
+            Gio.io_error_quark(),
+            "Timeout was reached",
+            Gio.IOErrorEnum.TIMED_OUT
+        ))
+
+        with self.assertRaises(TimeoutError) as cm:
+            self.proxy.Method1()
+
+        self.assertEqual(
+            str(cm.exception),
+            "The DBus call timeout was reached."
+        )
+
         # Handle local exception.
         self._set_reply(Exception("My message."))
 
diff --git a/tests/test_dbus.py b/tests/test_dbus.py
index d62e25c..4e372dc 100644
--- a/tests/test_dbus.py
+++ b/tests/test_dbus.py
@@ -283,6 +283,27 @@ class DBusTestCase(unittest.TestCase):
 
         self.assertEqual(sorted(self.service._names), ["Bar", "Foo"])
 
+    def test_timeout(self):
+        """Call a DBus method with a timeout."""
+        self._set_service(ExampleInterface())
+        self.assertEqual(self.service._names, [])
+
+        def test1():
+            proxy = self._get_proxy()
+            proxy.Hello("Foo", timeout=1000)
+
+        def test2():
+            proxy = self._get_proxy()
+
+            with self.assertRaises(TimeoutError):
+                proxy.Hello("Bar", timeout=0)
+
+        self._add_client(test1)
+        self._add_client(test2)
+        self._run_test()
+
+        self.assertEqual(sorted(self.service._names), ["Bar", "Foo"])
+
     def test_name(self):
         """Use a DBus read-only property."""
         self._set_service(ExampleInterface())
-- 
2.33.0