Backport selector performance improvements from cpython

python/cpython#106665
python/cpython#106555
python/cpython#106754
python/cpython#106528

Author: bdraco

python/3.11/gh-106527-asyncio-optimize-to-add-remove-readers-and.patch

@@ -0,0 +1,113 @@
+From b7dc795dfd175c0d25a479cfaf94a13c368a5a7b Mon Sep 17 00:00:00 2001
+From: "J. Nick Koston" <[email protected]>
+Date: Sat, 22 Jul 2023 16:07:40 -0500
+Subject: [PATCH] gh-106527: asyncio: optimize to add/remove readers and
+ writers (#106528)
+
+---
+ Lib/asyncio/selector_events.py                | 64 +++++++++----------
+ Lib/test/test_asyncio/test_selector_events.py | 36 +++++------
+ 2 files changed, 47 insertions(+), 53 deletions(-)
+
+diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
+index f895750e3c..d521b4e2e2 100644
+--- a/Lib/asyncio/selector_events.py
++++ b/Lib/asyncio/selector_events.py
+@@ -274,9 +274,8 @@ def _ensure_fd_no_transport(self, fd):
+     def _add_reader(self, fd, callback, *args):
+         self._check_closed()
+         handle = events.Handle(callback, args, self, None)
+-        try:
+-            key = self._selector.get_key(fd)
+-        except KeyError:
++        key = self._selector.get_map().get(fd)
++        if key is None:
+             self._selector.register(fd, selectors.EVENT_READ,
+                                     (handle, None))
+         else:
+@@ -290,30 +289,27 @@ def _add_reader(self, fd, callback, *args):
+     def _remove_reader(self, fd):
+         if self.is_closed():
+             return False
+-        try:
+-            key = self._selector.get_key(fd)
+-        except KeyError:
++        key = self._selector.get_map().get(fd)
++        if key is None:
+             return False
++        mask, (reader, writer) = key.events, key.data
++        mask &= ~selectors.EVENT_READ
++        if not mask:
++            self._selector.unregister(fd)
+         else:
+-            mask, (reader, writer) = key.events, key.data
+-            mask &= ~selectors.EVENT_READ
+-            if not mask:
+-                self._selector.unregister(fd)
+-            else:
+-                self._selector.modify(fd, mask, (None, writer))
++            self._selector.modify(fd, mask, (None, writer))
+ 
+-            if reader is not None:
+-                reader.cancel()
+-                return True
+-            else:
+-                return False
++        if reader is not None:
++            reader.cancel()
++            return True
++        else:
++            return False
+ 
+     def _add_writer(self, fd, callback, *args):
+         self._check_closed()
+         handle = events.Handle(callback, args, self, None)
+-        try:
+-            key = self._selector.get_key(fd)
+-        except KeyError:
++        key = self._selector.get_map().get(fd)
++        if key is None:
+             self._selector.register(fd, selectors.EVENT_WRITE,
+                                     (None, handle))
+         else:
+@@ -328,24 +324,22 @@ def _remove_writer(self, fd):
+         """Remove a writer callback."""
+         if self.is_closed():
+             return False
+-        try:
+-            key = self._selector.get_key(fd)
+-        except KeyError:
++        key = self._selector.get_map().get(fd)
++        if key is None:
+             return False
++        mask, (reader, writer) = key.events, key.data
++        # Remove both writer and connector.
++        mask &= ~selectors.EVENT_WRITE
++        if not mask:
++            self._selector.unregister(fd)
+         else:
+-            mask, (reader, writer) = key.events, key.data
+-            # Remove both writer and connector.
+-            mask &= ~selectors.EVENT_WRITE
+-            if not mask:
+-                self._selector.unregister(fd)
+-            else:
+-                self._selector.modify(fd, mask, (reader, None))
++            self._selector.modify(fd, mask, (reader, None))
+ 
+-            if writer is not None:
+-                writer.cancel()
+-                return True
+-            else:
+-                return False
++        if writer is not None:
++            writer.cancel()
++            return True
++        else:
++            return False
+ 
+     def add_reader(self, fd, callback, *args):
+         """Add a reader callback."""
+-- 
+2.39.2 (Apple Git-143)
+

python/3.11/gh-106554-replace-_BaseSelectorImpl._key_from_fd-wit.patch

@@ -0,0 +1,73 @@
+From aeef8591e41b68341af308e56a744396c66879cc Mon Sep 17 00:00:00 2001
+From: "J. Nick Koston" <[email protected]>
+Date: Fri, 14 Jul 2023 08:46:30 -1000
+Subject: [PATCH] gh-106554: replace `_BaseSelectorImpl._key_from_fd` with
+ `dict.get` (#106555)
+
+---
+ Lib/selectors.py | 21 ++++-----------------
+ 1 file changed, 4 insertions(+), 17 deletions(-)
+
+diff --git a/Lib/selectors.py b/Lib/selectors.py
+index dfcc125dcd..6d82935445 100644
+--- a/Lib/selectors.py
++++ b/Lib/selectors.py
+@@ -276,19 +276,6 @@ def close(self):
+     def get_map(self):
+         return self._map
+ 
+-    def _key_from_fd(self, fd):
+-        """Return the key associated to a given file descriptor.
+-
+-        Parameters:
+-        fd -- file descriptor
+-
+-        Returns:
+-        corresponding key, or None if not found
+-        """
+-        try:
+-            return self._fd_to_key[fd]
+-        except KeyError:
+-            return None
+ 
+ 
+ class SelectSelector(_BaseSelectorImpl):
+@@ -336,7 +323,7 @@ def select(self, timeout=None):
+             if fd in w:
+                 events |= EVENT_WRITE
+ 
+-            key = self._key_from_fd(fd)
++            key = self._fd_to_key.get(fd)
+             if key:
+                 ready.append((key, events & key.events))
+         return ready
+@@ -426,7 +413,7 @@ def select(self, timeout=None):
+             if event & ~self._EVENT_WRITE:
+                 events |= EVENT_READ
+ 
+-            key = self._key_from_fd(fd)
++            key = self._fd_to_key.get(fd)
+             if key:
+                 ready.append((key, events & key.events))
+         return ready
+@@ -479,7 +466,7 @@ def select(self, timeout=None):
+                 if event & ~select.EPOLLOUT:
+                     events |= EVENT_READ
+ 
+-                key = self._key_from_fd(fd)
++                key = self._fd_to_key.get(fd)
+                 if key:
+                     ready.append((key, events & key.events))
+             return ready
+@@ -574,7 +561,7 @@ def select(self, timeout=None):
+                 if flag == select.KQ_FILTER_WRITE:
+                     events |= EVENT_WRITE
+ 
+-                key = self._key_from_fd(fd)
++                key = self._fd_to_key.get(fd)
+                 if key:
+                     ready.append((key, events & key.events))
+             return ready
+-- 
+2.39.2 (Apple Git-143)
+

python/3.11/gh-106664-selectors-add-get-method-to-_SelectorMappi.patch

@@ -0,0 +1,43 @@
+From 8d2f3c36caf9ecdee1176314b18388aef6e7f2c2 Mon Sep 17 00:00:00 2001
+From: "J. Nick Koston" <[email protected]>
+Date: Thu, 13 Jul 2023 09:18:53 -1000
+Subject: [PATCH] gh-106664: selectors: add get() method to _SelectorMapping
+ (#106665)
+
+It can be used to avoid raising and catching KeyError twice via __getitem__.
+
+Co-authored-by: Inada Naoki <[email protected]>
+---
+ Lib/selectors.py           | 14 +++++++++-----
+ Lib/test/test_selectors.py |  6 ++++++
+ 2 files changed, 15 insertions(+), 5 deletions(-)
+
+diff --git a/Lib/selectors.py b/Lib/selectors.py
+index af6a4f94b5..dfcc125dcd 100644
+--- a/Lib/selectors.py
++++ b/Lib/selectors.py
+@@ -66,12 +66,16 @@ def __init__(self, selector):
+     def __len__(self):
+         return len(self._selector._fd_to_key)
+ 
++    def get(self, fileobj, default=None):
++        fd = self._selector._fileobj_lookup(fileobj)
++        return self._selector._fd_to_key.get(fd, default)
++
+     def __getitem__(self, fileobj):
+-        try:
+-            fd = self._selector._fileobj_lookup(fileobj)
+-            return self._selector._fd_to_key[fd]
+-        except KeyError:
+-            raise KeyError("{!r} is not registered".format(fileobj)) from None
++        fd = self._selector._fileobj_lookup(fileobj)
++        key = self._selector._fd_to_key.get(fd)
++        if key is None:
++            raise KeyError("{!r} is not registered".format(fileobj))
++        return key
+ 
+     def __iter__(self):
+         return iter(self._selector._fd_to_key)
+-- 
+2.39.2 (Apple Git-143)
+

python/3.11/gh-106751-selectors-optimize-EpollSelector.select-10.patch

@@ -0,0 +1,57 @@
+From aecf6aca515a203a823a87c711f15cbb82097c8b Mon Sep 17 00:00:00 2001
+From: "J. Nick Koston" <[email protected]>
+Date: Tue, 18 Jul 2023 00:16:32 -1000
+Subject: [PATCH] gh-106751: selectors: optimize EpollSelector.select()
+ (#106754)
+
+Co-authored-by: Pieter Eendebak <[email protected]>
+---
+ Lib/selectors.py | 17 +++++++++--------
+ 1 file changed, 9 insertions(+), 8 deletions(-)
+
+diff --git a/Lib/selectors.py b/Lib/selectors.py
+index 6d82935445..a42d156340 100644
+--- a/Lib/selectors.py
++++ b/Lib/selectors.py
+@@ -430,6 +430,9 @@ class PollSelector(_PollLikeSelector):
+ 
+ if hasattr(select, 'epoll'):
+ 
++    _NOT_EPOLLIN = ~select.EPOLLIN
++    _NOT_EPOLLOUT = ~select.EPOLLOUT
++
+     class EpollSelector(_PollLikeSelector):
+         """Epoll-based selector."""
+         _selector_cls = select.epoll
+@@ -452,22 +455,20 @@ def select(self, timeout=None):
+             # epoll_wait() expects `maxevents` to be greater than zero;
+             # we want to make sure that `select()` can be called when no
+             # FD is registered.
+-            max_ev = max(len(self._fd_to_key), 1)
++            max_ev = len(self._fd_to_key) or 1
+ 
+             ready = []
+             try:
+                 fd_event_list = self._selector.poll(timeout, max_ev)
+             except InterruptedError:
+                 return ready
+-            for fd, event in fd_event_list:
+-                events = 0
+-                if event & ~select.EPOLLIN:
+-                    events |= EVENT_WRITE
+-                if event & ~select.EPOLLOUT:
+-                    events |= EVENT_READ
+ 
+-                key = self._fd_to_key.get(fd)
++            fd_to_key = self._fd_to_key
++            for fd, event in fd_event_list:
++                key = fd_to_key.get(fd)
+                 if key:
++                    events = ((event & _NOT_EPOLLIN and EVENT_WRITE)
++                              | (event & _NOT_EPOLLOUT and EVENT_READ))
+                     ready.append((key, events & key.events))
+             return ready
+ 
+-- 
+2.39.2 (Apple Git-143)
+