netutil: Use a threaded resolver by default

Uses IOLoop.run_in_executor.
concurrent.futures is now required on Python 2.

diff --git a/.travis.yml b/.travis.yml
index cd2021bd6a8f627ec7d9ba30f62f723f35af3263..df37efa50a15126158974e6d61a07b532b2e9aea 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,8 +20,8 @@ python:
     - pypy3.5-5.8.0
 
 install:
-    - if [[ $TRAVIS_PYTHON_VERSION == 2* ]]; then travis_retry pip install futures mock monotonic; fi
-    - if [[ $TRAVIS_PYTHON_VERSION == 'pypy' ]]; then travis_retry pip install futures mock; fi
+    - if [[ $TRAVIS_PYTHON_VERSION == 2* ]]; then travis_retry pip install mock monotonic; fi
+    - if [[ $TRAVIS_PYTHON_VERSION == 'pypy' ]]; then travis_retry pip install mock; fi
     # TODO(bdarnell): pycares tests are currently disabled on travis due to ipv6 issues.
     #- if [[ $TRAVIS_PYTHON_VERSION != 'pypy'* ]]; then travis_retry pip install pycares; fi
     - if [[ $TRAVIS_PYTHON_VERSION != 'pypy'* ]]; then travis_retry pip install pycurl; fi
@@ -66,7 +66,6 @@ script:
     - LANG=C python $TARGET
     - LANG=en_US.utf-8 python $TARGET
     - if [[ $TRAVIS_PYTHON_VERSION == 3* ]]; then python -bb $TARGET; fi
-    - if [[ $TRAVIS_PYTHON_VERSION != pypy* ]]; then python $TARGET --resolver=tornado.netutil.ThreadedResolver; fi
     - if [[ $TRAVIS_PYTHON_VERSION == 2* ]]; then python $TARGET --httpclient=tornado.curl_httpclient.CurlAsyncHTTPClient; fi
     - if [[ $TRAVIS_PYTHON_VERSION == 2* ]]; then python $TARGET --ioloop=tornado.platform.twisted.TwistedIOLoop; fi
     - if [[ $TRAVIS_PYTHON_VERSION == 2* ]]; then python $TARGET --resolver=tornado.platform.twisted.TwistedResolver; fi

diff --git a/docs/guide/async.rst b/docs/guide/async.rst
index 5082f3fba45b131f1232ecb16ad101523789ceca..60f8a23b34a77151829a2613c9dd031b751ab651 100644 (file)
--- a/docs/guide/async.rst
+++ b/docs/guide/async.rst
@@ -27,11 +27,7 @@ hundreds of milliseconds of CPU time, far more than a typical network
 or disk access).
 
 A function can be blocking in some respects and non-blocking in
-others.  For example, `tornado.httpclient` in the default
-configuration blocks on DNS resolution but not on other network access
-(to mitigate this use `.ThreadedResolver` or a
-``tornado.curl_httpclient`` with a properly-configured build of
-``libcurl``).  In the context of Tornado we generally talk about
+others.  In the context of Tornado we generally talk about
 blocking in the context of network I/O, although all kinds of blocking
 are to be minimized.
 

diff --git a/docs/index.rst b/docs/index.rst
index ed24eb6232b8082ec22c550f6f0cc386f15f961d..ce4156c4fcb8579788c72f4bff5b28bf54f155b0 100644 (file)
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -73,10 +73,6 @@ older python versions). In addition to the requirements
 which will be installed automatically by ``pip`` or ``setup.py install``,
 the following optional packages may be useful:
 
-* `concurrent.futures <https://pypi.python.org/pypi/futures>`_ is the
-  recommended thread pool for use with Tornado and enables the use of
-  `~tornado.netutil.ThreadedResolver`.  It is needed only on Python 2;
-  Python 3 includes this package in the standard library.
 * `pycurl <http://pycurl.sourceforge.net>`_ is used by the optional
   ``tornado.curl_httpclient``.  Libcurl version 7.22 or higher is required.
 * `Twisted <http://www.twistedmatrix.com>`_ may be used with the classes in

diff --git a/docs/releases/v5.0.0.rst b/docs/releases/v5.0.0.rst
index 6456090d8b4098c9849e9f70b50d6c355702b2e1..0ef227a980e038489d7a690ec38726919d61be95 100644 (file)
--- a/docs/releases/v5.0.0.rst
+++ b/docs/releases/v5.0.0.rst
@@ -71,6 +71,8 @@ Backwards-compatibility notes
 Other notes
 ~~~~~~~~~~~
 
+- The ``futures`` (`concurrent.futures` backport) package is now required
+  on Python 2.7.
 - The ``certifi`` and ``backports.ssl-match-hostname`` packages are no
   longer required on Python 2.7.
 - Python 3.6 or higher is recommended, because it features more
@@ -204,6 +206,9 @@ Other notes
 `tornado.netutil`
 ~~~~~~~~~~~~~~~~~
 
+- The default `.Resolver` now uses `.IOLoop.run_in_executor`.
+  `.ExecutorResolver`, `.BlockingResolver`, and `.ThreadedResolver` are
+  deprecated.
 - The ``io_loop`` arguments to `.add_accept_handler`,
   `.ExecutorResolver`, and `.ThreadedResolver` have been removed.
 - `.add_accept_handler` returns a callable which can be used to remove

diff --git a/setup.py b/setup.py
index 26bb716d52a490533091056a1d72486390f1c543..37ea05942620797bc469c7e6de228a94eca87e36 100644 (file)
--- a/setup.py
+++ b/setup.py
@@ -127,6 +127,8 @@ if (platform.python_implementation() == 'CPython' and
 if setuptools is not None:
     # If setuptools is not available, you're on your own for dependencies.
     install_requires = []
+    if sys.version_info < (3, 2):
+        install_requires.append('futures')
     if sys.version_info < (3, 4):
         install_requires.append('singledispatch')
     if sys.version_info < (3, 5):

diff --git a/tornado/netutil.py b/tornado/netutil.py
index 1469b90c0b972d502da0a10be8e501c12b012079..caaa09090cc55cc20c10724e2090a2e0d2bff968 100644 (file)
--- a/tornado/netutil.py
+++ b/tornado/netutil.py
@@ -25,6 +25,7 @@ import socket
 import stat
 
 from tornado.concurrent import dummy_executor, run_on_executor
+from tornado import gen
 from tornado.ioloop import IOLoop
 from tornado.platform.auto import set_close_exec
 from tornado.util import PY3, Configurable, errno_from_exception
@@ -292,11 +293,16 @@ class Resolver(Configurable):
 
     The implementations of this interface included with Tornado are
 
-    * `tornado.netutil.BlockingResolver`
-    * `tornado.netutil.ThreadedResolver`
+    * `tornado.netutil.DefaultExecutorResolver`
+    * `tornado.netutil.BlockingResolver` (deprecated)
+    * `tornado.netutil.ThreadedResolver` (deprecated)
     * `tornado.netutil.OverrideResolver`
     * `tornado.platform.twisted.TwistedResolver`
     * `tornado.platform.caresresolver.CaresResolver`
+
+    .. versionchanged:: 5.0
+       The default implementation has changed from `BlockingResolver` to
+       `DefaultExecutorResolver`.
     """
     @classmethod
     def configurable_base(cls):
@@ -304,7 +310,7 @@ class Resolver(Configurable):
 
     @classmethod
     def configurable_default(cls):
-        return BlockingResolver
+        return DefaultExecutorResolver
 
     def resolve(self, host, port, family=socket.AF_UNSPEC, callback=None):
         """Resolves an address.
@@ -335,6 +341,31 @@ class Resolver(Configurable):
         pass
 
 
+def _resolve_addr(host, port, family=socket.AF_UNSPEC):
+    # On Solaris, getaddrinfo fails if the given port is not found
+    # in /etc/services and no socket type is given, so we must pass
+    # one here.  The socket type used here doesn't seem to actually
+    # matter (we discard the one we get back in the results),
+    # so the addresses we return should still be usable with SOCK_DGRAM.
+    addrinfo = socket.getaddrinfo(host, port, family, socket.SOCK_STREAM)
+    results = []
+    for family, socktype, proto, canonname, address in addrinfo:
+        results.append((family, address))
+    return results
+
+
+class DefaultExecutorResolver(Resolver):
+    """Resolver implementation using `.IOLoop.run_in_executor`.
+
+    .. versionadded:: 5.0
+    """
+    @gen.coroutine
+    def resolve(self, host, port, family=socket.AF_UNSPEC):
+        result = yield IOLoop.current().run_in_executor(
+            None, _resolve_addr, host, port, family)
+        raise gen.Return(result)
+
+
 class ExecutorResolver(Resolver):
     """Resolver implementation using a `concurrent.futures.Executor`.
 
@@ -347,6 +378,10 @@ class ExecutorResolver(Resolver):
 
     .. versionchanged:: 5.0
        The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+
+    .. deprecated:: 5.0
+       The default `Resolver` now uses `.IOLoop.run_in_executor`; use that instead
+       of this class.
     """
     def initialize(self, executor=None, close_executor=True):
         self.io_loop = IOLoop.current()
@@ -364,16 +399,7 @@ class ExecutorResolver(Resolver):
 
     @run_on_executor
     def resolve(self, host, port, family=socket.AF_UNSPEC):
-        # On Solaris, getaddrinfo fails if the given port is not found
-        # in /etc/services and no socket type is given, so we must pass
-        # one here.  The socket type used here doesn't seem to actually
-        # matter (we discard the one we get back in the results),
-        # so the addresses we return should still be usable with SOCK_DGRAM.
-        addrinfo = socket.getaddrinfo(host, port, family, socket.SOCK_STREAM)
-        results = []
-        for family, socktype, proto, canonname, address in addrinfo:
-            results.append((family, address))
-        return results
+        return _resolve_addr(host, port, family)
 
 
 class BlockingResolver(ExecutorResolver):
@@ -381,6 +407,10 @@ class BlockingResolver(ExecutorResolver):
 
     The `.IOLoop` will be blocked during the resolution, although the
     callback will not be run until the next `.IOLoop` iteration.
+
+    .. deprecated:: 5.0
+       The default `Resolver` now uses `.IOLoop.run_in_executor`; use that instead
+       of this class.
     """
     def initialize(self):
         super(BlockingResolver, self).initialize()
@@ -401,6 +431,10 @@ class ThreadedResolver(ExecutorResolver):
     .. versionchanged:: 3.1
        All ``ThreadedResolvers`` share a single thread pool, whose
        size is set by the first one to be created.
+
+    .. deprecated:: 5.0
+       The default `Resolver` now uses `.IOLoop.run_in_executor`; use that instead
+       of this class.
     """
     _threadpool = None  # type: ignore
     _threadpool_pid = None  # type: int

diff --git a/tornado/platform/twisted.py b/tornado/platform/twisted.py
index f8d32193ea243e6c256eea37d58230d4a4ef30e2..43e447c13dbb4276f3ea48d16c8ab0a2edd8aac6 100644 (file)
--- a/tornado/platform/twisted.py
+++ b/tornado/platform/twisted.py
@@ -520,7 +520,7 @@ class TwistedResolver(Resolver):
     recommended only when threads cannot be used, since it has
     limitations compared to the standard ``getaddrinfo``-based
     `~tornado.netutil.Resolver` and
-    `~tornado.netutil.ThreadedResolver`.  Specifically, it returns at
+    `~tornado.netutil.DefaultExecutorResolver`.  Specifically, it returns at
     most one result, and arguments other than ``host`` and ``family``
     are ignored.  It may fail to resolve when ``family`` is not
     ``socket.AF_UNSPEC``.

diff --git a/tox.ini b/tox.ini
index 2cc0a67ce78c61248d6a06465d3d7a39c6e79a6d..603914b5468baa404152f078e8d99d9a9473136e 100644 (file)
--- a/tox.ini
+++ b/tox.ini
@@ -32,7 +32,6 @@ envlist =
         py2-twistedlayered,
 
         # Alternate Resolvers.
-        {py2,py3}-full-{threadedresolver},
         {py2,py3}-full-caresresolver,
 
         # Other configurations; see comments below.
@@ -73,8 +72,6 @@ deps =
      {py27,py34,py35,py36}-full: twisted
      {py2,py3}: twisted
      {py2,py3,py27,py34,py35,py36}-full: pycares
-     # futures became standard in py32
-     {py2,py27,pypy}-full: futures
      # mock became standard in py33
      {py2,py27,pypy,pypy3}-full: mock
      # singledispatch became standard in py34.