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.

diff --git a/docs/caresresolver.rst b/docs/caresresolver.rst
index b5d6ddd1019437c1b5abee9dc3f84a5a081f816a..4e0058eac09c750202f900c1e489d346be5f4f96 100644 (file)
--- 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
index f834eb55b212eabc845f74216d65cf59411ac8fa..5d8fe8fbc80d01a93009ad231f8a3f5f6736278c 100644 (file)
--- 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
index e2c5009ac0c632bf52605284e4088b604a09fb69..962f84f48f53d9ed5ab621e513eabcdac9bd9c08 100644 (file)
--- 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
index 0987a84ab74f78d12174fa8d2bc82121356644fe..153fe436eb83159767b4ca801866022ece723a3e 100644 (file)
--- 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: