Nir Soffer has uploaded a new change for review.
Change subject: vdsm: add eventfd and EventFile synchronization
......................................................................
vdsm: add eventfd and EventFile synchronization
Change-Id: I0d237f13c42b1f4505c90d30c6d3c3ecbd1e9fa7
Signed-off-by: Federico Simoncelli <fsimo...@redhat.com>
---
M lib/vdsm/Makefile.am
A lib/vdsm/eventfd.py
M tests/Makefile.am
A tests/eventfdTests.py
4 files changed, 251 insertions(+), 0 deletions(-)
git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/87/33687/1
diff --git a/lib/vdsm/Makefile.am b/lib/vdsm/Makefile.am
index 4bebf28..e712cad 100644
--- a/lib/vdsm/Makefile.am
+++ b/lib/vdsm/Makefile.am
@@ -25,6 +25,7 @@
__init__.py \
compat.py \
define.py \
+ eventfd.py \
exception.py \
ipwrapper.py \
libvirtconnection.py \
diff --git a/lib/vdsm/eventfd.py b/lib/vdsm/eventfd.py
new file mode 100644
index 0000000..b2a7084
--- /dev/null
+++ b/lib/vdsm/eventfd.py
@@ -0,0 +1,140 @@
+#
+# Copyright 2014 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+#
+# Refer to the README and COPYING files for full details of the license
+#
+
+"""\
+This module provides the support for eventfd(2).
+
+More information about eventfd and usage examples can be found in the
+eventfd(2) man page.
+
+The EventFile class provides a single synchronization object exposing
+the python Event interface and associated eventfds.
+
+The eventfd() context manager returns a file descriptor that can be
+used to provide the event notice to select, poll and epoll, e.g.
+
+ import os
+ import sys
+ import select
+ import threading
+ import time
+ from vdsm.eventfd import EventFile, DATASIZE
+
+ e = EventFile()
+ p = select.epoll()
+
+ threading.Timer(5, e.set).start()
+
+ with e.eventfd() as efd:
+ p.register(efd, select.EPOLLIN)
+ p.register(sys.stdin.fileno(), select.EPOLLIN)
+
+ print "Echoing lines until event is received"
+ event_received = False
+
+ while not event_received:
+ for fileno, event in p.poll():
+ if not event & select.EPOLLIN:
+ continue
+
+ if fileno == efd:
+ os.read(efd, DATASIZE)
+ event_received = True
+ elif fileno == sys.stdin.fileno():
+ print os.read(sys.stdin.fileno(), 1024),
+
+ print "Event received!"
+
+
+The Event set() semantic is preserved in the eventfd context manager:
+if the event is set then the eventfd already contains the notification.
+This is both to maintain the semantic and to avoid possible races as:
+
+ if not e.is_set():
+ with e.eventfd() as efd:
+ ...
+"""
+
+import os
+import ctypes
+import threading
+
+from contextlib import contextmanager
+
+_libc = ctypes.CDLL('libc.so.6', use_errno=True)
+
+EFD_NONBLOCK = os.O_NONBLOCK
+EFD_CLOEXEC = 02000000 # os.O_CLOEXEC in python 3.3
+EFD_SEMAPHORE = 00000001
+
+DATASIZE = ctypes.sizeof(ctypes.c_ulonglong)
+
+
+def eventfd(initval, flags):
+ return _libc.eventfd(initval, flags)
+
+
+class EventFile(object):
+ def __init__(self, event=None):
+ self.__lock = threading.Lock()
+ self.__fds = set()
+ self.__event = event or threading.Event()
+
+ @staticmethod
+ def __fire_event(fd):
+ os.write(fd, ctypes.c_ulonglong(1))
+
+ def open_eventfd(self):
+ with self.__lock:
+ fd = eventfd(0, 0)
+
+ self.__fds.add(fd)
+
+ if self.__event.is_set():
+ self.__fire_event(fd)
+
+ return fd
+
+ @contextmanager
+ def eventfd(self):
+ fd = self.open_eventfd()
+
+ yield fd
+
+ with self.__lock:
+ self.__fds.remove(fd)
+ os.close(fd)
+
+ def isSet(self):
+ return self.__event.isSet()
+
+ is_set = isSet
+
+ def set(self):
+ with self.__lock:
+ self.__event.set()
+ for fd in self.__fds:
+ self.__fire_event(fd)
+
+ def clear(self):
+ self.__event.clear()
+
+ def wait(self, timeout=None, balancing=True):
+ self.__event.wait(timeout)
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 449d7b1..120712e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -31,6 +31,7 @@
clientifTests.py \
configNetworkTests.py \
domainMonitorTests.py \
+ eventfdTests.py \
fileVolumeTests.py \
fileUtilTests.py \
fuserTests.py \
diff --git a/tests/eventfdTests.py b/tests/eventfdTests.py
new file mode 100644
index 0000000..be15248
--- /dev/null
+++ b/tests/eventfdTests.py
@@ -0,0 +1,109 @@
+#
+# Copyright 2014 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+#
+# Refer to the README and COPYING files for full details of the license
+#
+
+import os
+import select
+from vdsm.eventfd import EventFile, DATASIZE
+from nose.tools import timed, raises, TimeExpired
+
+TEST_TIMEOUT = 1
+WAIT_TIMEOUT = 2
+
+
+def test_set():
+ e = EventFile()
+ e.set()
+ assert e.is_set()
+ assert e.isSet()
+
+
+def text_clear():
+ e = EventFile()
+ e.set()
+ assert e.is_set()
+ e.clear()
+ assert not e.is_set()
+
+
+@timed(TEST_TIMEOUT)
+def test_wait_set():
+ e = EventFile()
+ e.set()
+ e.wait(WAIT_TIMEOUT)
+
+
+@raises(TimeExpired)
+@timed(TEST_TIMEOUT)
+def test_wait_noset():
+ e = EventFile()
+ e.wait(WAIT_TIMEOUT)
+
+
+@timed(TEST_TIMEOUT)
+def test_eventfd_earlyset():
+ e = EventFile()
+ e.set()
+ with e.eventfd() as fd:
+ assert len(__select_and_read(fd)) == DATASIZE
+
+
+@timed(TEST_TIMEOUT)
+def test_eventfd_lateset():
+ e = EventFile()
+ with e.eventfd() as fd:
+ e.set()
+ assert len(__select_and_read(fd)) == DATASIZE
+
+
+@raises(TimeExpired)
+@timed(TEST_TIMEOUT)
+def test_eventfd_noset():
+ e = EventFile()
+ with e.eventfd() as fd:
+ assert len(__select_and_read(fd)) != DATASIZE
+
+
+@timed(TEST_TIMEOUT)
+def test_eventfd_multiple():
+ e = EventFile()
+ e.set()
+ with e.eventfd() as fd1:
+ assert len(__select_and_read(fd1)) == DATASIZE
+ with e.eventfd() as fd2:
+ assert len(__select_and_read(fd2)) == DATASIZE
+ with e.eventfd() as fd3:
+ assert len(__select_and_read(fd3)) == DATASIZE
+
+
+@raises(TimeExpired)
+@timed(TEST_TIMEOUT)
+def test_eventfd_clear():
+ e = EventFile()
+ e.set()
+ e.clear()
+ with e.eventfd() as fd:
+ assert len(__select_and_read(fd)) != DATASIZE
+
+
+def __select_and_read(fd):
+ rd, wr, ex = select.select((fd,), (), (), WAIT_TIMEOUT)
+ if fd in rd:
+ return os.read(fd, DATASIZE)
+ return ''
--
To view, visit https://gerrit.ovirt.org/33687
To unsubscribe, visit https://gerrit.ovirt.org/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I0d237f13c42b1f4505c90d30c6d3c3ecbd1e9fa7
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Federico Simoncelli <fsimo...@redhat.com>
Gerrit-Reviewer: Dan Kenigsberg <dan...@redhat.com>
Gerrit-Reviewer: Federico Simoncelli <fsimo...@redhat.com>
Gerrit-Reviewer: Francesco Romani <from...@redhat.com>
Gerrit-Reviewer: Jenkins CI
Gerrit-Reviewer: Jenkins CI RO
Gerrit-Reviewer: Nir Soffer <nsof...@redhat.com>
Gerrit-Reviewer: Saggi Mizrahi <smizr...@redhat.com>
Gerrit-Reviewer: gerrit-hooks <automat...@ovirt.org>
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