From b155da424a0b2a48b3c248decac809ecaf93408c Mon Sep 17 00:00:00 2001
From: Flaper Fesp <flaper87@gmail.com>
Date: Wed, 2 Jan 2013 12:20:02 +0100
Subject: [PATCH] Check whether poll is available or not and let eventlet chose
 the best hub when it isn't.

Change-Id: I5fb05a71e8c62d84cee1da9ea05f67ffbad18b9d
---
 swift/common/utils.py   | 25 +++++++++++++++++++++++++
 swift/common/wsgi.py    |  5 +++--
 swift/obj/replicator.py |  4 ++--
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/swift/common/utils.py b/swift/common/utils.py
index fc28fb74e3..233c3c96af 100644
--- a/swift/common/utils.py
+++ b/swift/common/utils.py
@@ -751,6 +751,31 @@ def get_logger(conf, name=None, log_to_console=False, log_route=None,
     return adapted_logger
 
 
+def get_hub():
+    """
+    Checks whether poll is available and falls back
+    on select if it isn't.
+
+    Note about epoll:
+
+    Review: https://review.openstack.org/#/c/18806/
+
+    There was a problem where once out of every 30 quadrillion
+    connections, a coroutine wouldn't wake up when the client
+    closed its end. Epoll was not reporting the event or it was
+    getting swallowed somewhere. Then when that file descriptor
+    was re-used, eventlet would freak right out because it still
+    thought it was waiting for activity from it in some other coro.
+    """
+    try:
+        import select
+        if hasattr(select, "poll"):
+            return "poll"
+        return "selects"
+    except ImportError:
+        return None
+
+
 def drop_privileges(user):
     """
     Sets the userid/groupid of the current process, get session leader, etc.
diff --git a/swift/common/wsgi.py b/swift/common/wsgi.py
index 8a892a67e3..02dccfba99 100644
--- a/swift/common/wsgi.py
+++ b/swift/common/wsgi.py
@@ -33,7 +33,7 @@ from urllib import unquote
 from swift.common.swob import Request
 from swift.common.utils import capture_stdio, disable_fallocate, \
     drop_privileges, get_logger, NullLogger, config_true_value, \
-    validate_configuration
+    validate_configuration, get_hub
 
 
 def monkey_patch_mimetools():
@@ -135,7 +135,8 @@ def run_wsgi(conf_file, app_section, *args, **kwargs):
         wsgi.HttpProtocol.log_message = \
             lambda s, f, *a: logger.error('ERROR WSGI: ' + f % a)
         wsgi.WRITE_TIMEOUT = int(conf.get('client_timeout') or 60)
-        eventlet.hubs.use_hub('poll')
+
+        eventlet.hubs.use_hub(get_hub())
         eventlet.patcher.monkey_patch(all=False, socket=True)
         eventlet_debug = config_true_value(conf.get('eventlet_debug', 'no'))
         eventlet.debug.hub_exceptions(eventlet_debug)
diff --git a/swift/obj/replicator.py b/swift/obj/replicator.py
index fb1d6974f3..56cceb5b95 100644
--- a/swift/obj/replicator.py
+++ b/swift/obj/replicator.py
@@ -33,13 +33,13 @@ from eventlet.support.greenlets import GreenletExit
 from swift.common.ring import Ring
 from swift.common.utils import whataremyips, unlink_older_than, lock_path, \
     compute_eta, get_logger, write_pickle, renamer, dump_recon_cache, \
-    rsync_ip, mkdirs, config_true_value, list_from_csv
+    rsync_ip, mkdirs, config_true_value, list_from_csv, get_hub
 from swift.common.bufferedhttp import http_connect
 from swift.common.daemon import Daemon
 from swift.common.http import HTTP_OK, HTTP_INSUFFICIENT_STORAGE
 from swift.common.exceptions import PathNotDir
 
-hubs.use_hub('poll')
+hubs.use_hub(get_hub())
 
 PICKLE_PROTOCOL = 2
 ONE_WEEK = 604800