[IMPR] Add a WaitingMixin to Requests and SparqlQuery class

Add a WaitingMixin class which handles wait cycles to Requests and
SparqlQuery class to prevent code duplication.

Change-Id: Id1f528044a4d95587431b0ccd7fa10330c6a9826
---
M pywikibot/data/sparql.py
M pywikibot/data/__init__.py
M pywikibot/data/api/_requests.py
3 files changed, 81 insertions(+), 45 deletions(-)

diff --git a/pywikibot/data/__init__.py b/pywikibot/data/__init__.py
index 7db53e3..1dd0b02 100644
--- a/pywikibot/data/__init__.py
+++ b/pywikibot/data/__init__.py
@@ -1,6 +1,56 @@
 """Module providing several layers of data access to the wiki."""
 #
-# (C) Pywikibot team, 2007-2022
+# (C) Pywikibot team, 2007-2023
 #
 # Distributed under the terms of the MIT license.
 #
+from typing import Optional
+
+import pywikibot
+
+
+class WaitingMixin:
+
+    """A mixin to implement wait cycles.
+
+    .. versionadded:: 8.4
+
+    :ivar int max_retries: Maximum number of times to retry an API
+        request before quitting. Defaults to ``config.max_retries`` if
+        attribute is missing.
+    :ivar int retry_wait: Minimum time to wait before resubmitting a
+        failed API request. Defaults to ``config.retry_wait`` if
+        attribute is missing.
+    :ivar int current_retries: counter of retries made for the current
+        request. Starting with 1 if attribute is missing.
+    """
+
+    def wait(self, delay: Optional[int] = None) -> None:
+        """Determine how long to wait after a failed request.
+
+        :param delay: Minimum time in seconds to wait. Overwrites
+            ``retry_wait`` variable if given. The delay doubles each
+            retry until ``retry_max`` seconds is reached.
+        """
+        if not hasattr(self, 'max_retries'):
+            self.max_retries = pywikibot.config.max_retries
+
+        if not hasattr(self, 'retry_wait'):
+            self.retry_wait = pywikibot.config.retry_wait
+
+        if self.current_retries > self.max_retries:
+            raise pywikibot.exceptions.TimeoutError(
+                'Maximum retries attempted without success.')
+
+        if not hasattr(self, 'current_retries'):
+            self.current_retries = 1
+        else:
+            self.current_retries += 1
+
+        # double the next wait, but do not exceed config.retry_max seconds
+        delay = delay or self.retry_wait
+        delay *= 2 ** (self.current_retries - 1)
+        delay = min(delay, pywikibot.config.retry_max)
+
+        pywikibot.warning(f'Waiting {delay:.1f} seconds before retrying.')
+        pywikibot.sleep(delay)
diff --git a/pywikibot/data/api/_requests.py b/pywikibot/data/api/_requests.py
index 7e7758c..e13bd6f 100644
--- a/pywikibot/data/api/_requests.py
+++ b/pywikibot/data/api/_requests.py
@@ -24,6 +24,7 @@
 from pywikibot import config
 from pywikibot.backports import Callable, Dict, Match, Tuple, removeprefix
 from pywikibot.comms import http
+from pywikibot.data import WaitingMixin
 from pywikibot.exceptions import (
     Client414Error,
     Error,
@@ -32,7 +33,6 @@
     NoUsernameError,
     Server504Error,
     SiteDefinitionError,
-    TimeoutError,
 )
 from pywikibot.login import LoginStatus
 from pywikibot.textlib import removeDisabledParts, removeHTMLParts
@@ -72,7 +72,7 @@
     r'Waiting for [\w.: ]+: (?P<lag>\d+(?:\.\d+)?) seconds? lagged')
 
 
-class Request(MutableMapping):
+class Request(MutableMapping, WaitingMixin):
 
     """A request to a Site's api.php interface.
 
@@ -126,6 +126,9 @@
     True
     >>> sorted(data['query'])
     ['namespaces', 'userinfo']
+
+    .. versionchanged:: 8.4
+       inherited from WaitingMixin.
     """
 
     # To make sure the default value of 'parameters' can be identified.
@@ -194,14 +197,9 @@
 
         self.throttle = throttle
         self.use_get = use_get
-        if max_retries is None:
-            self.max_retries = pywikibot.config.max_retries
-        else:
+        if max_retries is not None:
             self.max_retries = max_retries
-        self.current_retries = 0
-        if retry_wait is None:
-            self.retry_wait = pywikibot.config.retry_wait
-        else:
+        if retry_wait is not None:
             self.retry_wait = retry_wait
         self.json_warning = False
         # The only problem with that system is that it won't detect when
@@ -1120,20 +1118,6 @@
 
         raise MaxlagTimeoutError(msg)
 
-    def wait(self, delay=None):
-        """Determine how long to wait after a failed request."""
-        self.current_retries += 1
-        if self.current_retries > self.max_retries:
-            raise TimeoutError('Maximum retries attempted without success.')
-
-        # double the next wait, but do not exceed config.retry_max seconds
-        delay = delay or self.retry_wait
-        delay *= 2 ** (self.current_retries - 1)
-        delay = min(delay, config.retry_max)
-
-        pywikibot.warning(f'Waiting {delay:.1f} seconds before retrying.')
-        pywikibot.sleep(delay)
-
 
 class CachedRequest(Request):
 
diff --git a/pywikibot/data/sparql.py b/pywikibot/data/sparql.py
index 5c4e14e..23ffb1d 100644
--- a/pywikibot/data/sparql.py
+++ b/pywikibot/data/sparql.py
@@ -10,10 +10,11 @@
 
 from requests.exceptions import Timeout
 
-from pywikibot import Site, config, sleep, warning
+from pywikibot import Site
 from pywikibot.backports import Dict, List, removeprefix
 from pywikibot.comms import http
-from pywikibot.exceptions import Error, TimeoutError
+from pywikibot.data import WaitingMixin
+from pywikibot.exceptions import Error
 
 
 try:
@@ -25,11 +26,14 @@
                    'Accept': 'application/sparql-results+json'}
 
 
-class SparqlQuery:
-    """
-    SPARQL Query class.
+class SparqlQuery(WaitingMixin):
+    """SPARQL Query class.
 
     This class allows to run SPARQL queries against any SPARQL endpoint.
+
+    .. versionchanged:: 8.4
+       inherited from :class:`data.WaitingMixin` which provides a
+       :meth:`data.WaitingMixin.wait` method.
     """
 
     def __init__(self,
@@ -78,13 +82,9 @@
 
         self.last_response = None
 
-        if max_retries is None:
-            self.max_retries = config.max_retries
-        else:
+        if max_retries is not None:
             self.max_retries = max_retries
-        if retry_wait is None:
-            self.retry_wait = config.retry_wait
-        else:
+        if retry_wait is not None:
             self.retry_wait = retry_wait
 
     def get_last_response(self):
@@ -158,16 +158,6 @@
 
         return None
 
-    def wait(self):
-        """Determine how long to wait after a failed request."""
-        self.max_retries -= 1
-        if self.max_retries < 0:
-            raise TimeoutError('Maximum retries attempted without success.')
-        warning(f'Waiting {self.retry_wait} seconds before retrying.')
-        sleep(self.retry_wait)
-        # double the next wait, but do not exceed config.retry_max seconds
-        self.retry_wait = min(config.retry_max, self.retry_wait * 2)
-
     def ask(self, query: str,
             headers: Optional[Dict[str, str]] = None) -> bool:
         """

