platform: Deprecate twisted and cares resolvers

These were most interesting when the default resolver blocked the main thread. Now that the default is to use a thread pool, there is little if any demand for alternative resolvers just to avoid threads.
jeyrce · Aug 25, 2021 · b7b6f2a · b7b6f2a
1 parent 187e1a5
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diff --git a/docs/caresresolver.rst b/docs/caresresolver.rst
@@ -18,3 +18,7 @@ wrapper ``pycares``).
     so it is only recommended for use in ``AF_INET`` (i.e. IPv4).  This is
     the default for ``tornado.simple_httpclient``, but other libraries
     may default to ``AF_UNSPEC``.
+
+    .. deprecated:: 6.2
+       This class is deprecated and will be removed in Tornado 7.0. Use the default
+       thread-based resolver instead.
diff --git a/docs/twisted.rst b/docs/twisted.rst
@@ -53,3 +53,8 @@ Twisted DNS resolver
 
     .. versionchanged:: 5.0
        The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+
+    .. deprecated:: 6.2
+       This class is deprecated and will be removed in Tornado 7.0. Use the default
+       thread-based resolver instead.
+
diff --git a/tornado/platform/caresresolver.py b/tornado/platform/caresresolver.py
@@ -26,6 +26,10 @@ class CaresResolver(Resolver):
 
     .. versionchanged:: 5.0
        The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+
+    .. deprecated:: 6.2
+       This class is deprecated and will be removed in Tornado 7.0. Use the default
+       thread-based resolver instead.
     """
 
     def initialize(self) -> None:

diff --git a/tornado/platform/twisted.py b/tornado/platform/twisted.py
@@ -52,6 +52,10 @@ class TwistedResolver(Resolver):
 
     .. versionchanged:: 5.0
        The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+
+    .. deprecated:: 6.2
+       This class is deprecated and will be removed in Tornado 7.0. Use the default
+       thread-based resolver instead.
     """
 
     def initialize(self) -> None: