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#!/usr/bin/python
#
# Copyright (C) Citrix Systems Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; version 2.1 only.
#
# 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser 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
#
# Persistent reference counter. This refcounter can maintain two separate
# refcounts: one binary (which can have a value of 0 or 1) and one normal. The
# parameter "binary" specifies which of the two counters to update, while the
# return value is zero IFF both counters are zero
#
# Synchronization must be done at a higher level, by the users of this module
#
import os
import util
from lock import Lock
import errno
class RefCounterException(util.SMException):
pass
class RefCounter:
"""Persistent local-FS file-based reference counter. The
operations are get() and put(), and they are atomic."""
BASE_DIR = "/var/run/sm/refcount"
def get(obj, binary, ns = None):
"""Get (inc ref count) 'obj' in namespace 'ns' (optional).
Returns new ref count"""
if binary:
return RefCounter._adjust(ns, obj, 0, 1)
else:
return RefCounter._adjust(ns, obj, 1, 0)
get = staticmethod(get)
def put(obj, binary, ns = None):
"""Put (dec ref count) 'obj' in namespace 'ns' (optional). If ref
count was zero already, this operation is a no-op.
Returns new ref count"""
if binary:
return RefCounter._adjust(ns, obj, 0, -1)
else:
return RefCounter._adjust(ns, obj, -1, 0)
put = staticmethod(put)
def set(obj, count, binaryCount, ns = None):
"""Set normal & binary counts explicitly to the specified values.
Returns new ref count"""
(obj, ns) = RefCounter._getSafeNames(obj, ns)
assert(count >= 0 and binaryCount >= 0)
if binaryCount > 1:
raise RefCounterException("Binary count = %d > 1" % binaryCount)
RefCounter._set(ns, obj, count, binaryCount)
set = staticmethod(set)
def check(obj, ns = None):
"""Get the ref count values for 'obj' in namespace 'ns' (optional)"""
(obj, ns) = RefCounter._getSafeNames(obj, ns)
return RefCounter._get(ns, obj)
check = staticmethod(check)
def checkLocked(obj, ns):
"""Lock-protected access"""
lock = Lock(obj, ns)
lock.acquire()
try:
return RefCounter.check(obj, ns)
finally:
lock.release()
checkLocked = staticmethod(checkLocked)
def reset(obj, ns = None):
"""Reset ref counts for 'obj' in namespace 'ns' (optional) to 0."""
RefCounter.resetAll(ns, obj)
reset = staticmethod(reset)
def resetAll(ns = None, obj = None):
"""Reset ref counts of 'obj' in namespace 'ns' to 0. If obj is not
provided, reset all existing objects in 'ns' to 0. If neither obj nor
ns are supplied, do this for all namespaces"""
if obj:
(obj, ns) = RefCounter._getSafeNames(obj, ns)
if ns:
nsList = [ns]
else:
if not util.pathexists(RefCounter.BASE_DIR):
return
try:
nsList = os.listdir(RefCounter.BASE_DIR)
except OSError:
raise RefCounterException("failed to get namespace list")
for ns in nsList:
RefCounter._reset(ns, obj)
resetAll = staticmethod(resetAll)
def _adjust(ns, obj, delta, binaryDelta):
"""Add 'delta' to the normal refcount and 'binaryDelta' to the binary
refcount of 'obj' in namespace 'ns'.
Returns new ref count"""
115 if binaryDelta > 1 or binaryDelta < -1:
raise RefCounterException("Binary delta = %d outside [-1;1]" % \
binaryDelta)
(obj, ns) = RefCounter._getSafeNames(obj, ns)
(count, binaryCount) = RefCounter._get(ns, obj)
newCount = count + delta
newBinaryCount = binaryCount + binaryDelta
if newCount < 0:
util.SMlog("WARNING: decrementing normal refcount of 0")
newCount = 0
if newBinaryCount < 0:
util.SMlog("WARNING: decrementing binary refcount of 0")
newBinaryCount = 0
if newBinaryCount > 1:
newBinaryCount = 1
util.SMlog("Refcount for %s:%s (%d, %d) + (%d, %d) => (%d, %d)" % \
(ns, obj, count, binaryCount, delta, binaryDelta,
newCount, newBinaryCount))
RefCounter._set(ns, obj, newCount, newBinaryCount)
return newCount + newBinaryCount
_adjust = staticmethod(_adjust)
def _get(ns, obj):
"""Get the ref count values for 'obj' in namespace 'ns'"""
objFile = os.path.join(RefCounter.BASE_DIR, ns, obj)
(count, binaryCount) = (0, 0)
if util.pathexists(objFile):
(count, binaryCount) = RefCounter._readCount(objFile)
return (count, binaryCount)
_get = staticmethod(_get)
def _set(ns, obj, count, binaryCount):
"""Set the ref count values for 'obj' in namespace 'ns'"""
util.SMlog("Refcount for %s:%s set => (%d, %db)" % \
(ns, obj, count, binaryCount))
if count == 0 and binaryCount == 0:
RefCounter._removeObject(ns, obj)
else:
objFile = os.path.join(RefCounter.BASE_DIR, ns, obj)
while not RefCounter._writeCount(objFile, count, binaryCount):
RefCounter._createNamespace(ns)
_set = staticmethod(_set)
def _getSafeNames(obj, ns):
"""Get a name that can be used as a file name"""
if not ns:
ns = obj.split('/')[0]
if not ns:
ns = "default"
for char in ['/', '*', '?', '\\']:
obj = obj.replace(char, "_")
return (obj, ns)
_getSafeNames = staticmethod(_getSafeNames)
def _createNamespace(ns):
nsDir = os.path.join(RefCounter.BASE_DIR, ns)
try:
os.makedirs(nsDir)
except OSError, e:
if e.errno != errno.EEXIST:
raise RefCounterException("failed to makedirs '%s' (%s)" % \
(nsDir, e))
_createNamespace = staticmethod(_createNamespace)
def _removeObject(ns, obj):
nsDir = os.path.join(RefCounter.BASE_DIR, ns)
objFile = os.path.join(nsDir, obj)
if not util.pathexists(objFile):
return
try:
os.unlink(objFile)
except OSError:
raise RefCounterException("failed to remove '%s'" % objFile)
try:
os.rmdir(nsDir)
except OSError, e:
namespaceAlreadyCleanedUp = e.errno == errno.ENOENT
newObjectAddedToNamespace = e.errno == errno.ENOTEMPTY
200 if namespaceAlreadyCleanedUp or newObjectAddedToNamespace:
pass
else:
raise RefCounterException("failed to remove '%s'" % nsDir)
_removeObject = staticmethod(_removeObject)
def _reset(ns, obj = None):
nsDir = os.path.join(RefCounter.BASE_DIR, ns)
if not util.pathexists(nsDir):
return
if obj:
209 if not util.pathexists(os.path.join(nsDir, obj)):
return
objList = [obj]
else:
try:
objList = os.listdir(nsDir)
except OSError:
raise RefCounterException("failed to list '%s'" % ns)
for obj in objList:
RefCounter._removeObject(ns, obj)
_reset = staticmethod(_reset)
def _readCount(fn):
try:
f = open(fn, 'r')
line = f.readline()
nums = line.split()
count = int(nums[0])
binaryCount = int(nums[1])
f.close()
except IOError:
raise RefCounterException("failed to read file '%s'" % fn)
return (count, binaryCount)
_readCount = staticmethod(_readCount)
def _writeCount(fn, count, binaryCount):
try:
f = open(fn, 'w')
f.write("%d %d\n" % (count, binaryCount))
f.close()
return True
except IOError, e:
fileNotFound = e.errno == errno.ENOENT
243 if fileNotFound:
return False
raise RefCounterException("failed to write '(%d %d)' to '%s': %s" \
% (count, binaryCount, fn, e))
_writeCount = staticmethod(_writeCount)
def _runTests():
"Unit tests"
RefCounter.resetAll()
# A
(cnt, bcnt) = RefCounter.check("X", "A")
256 if cnt != 0 or bcnt != 0:
print "Error: check = %d != 0 in the beginning" % cnt
return -1
cnt = RefCounter.get("X", False, "A")
261 if cnt != 1:
print "Error: count = %d != 1 after first get()" % cnt
return -1
(cnt, bcnt) = RefCounter.check("X", "A")
265 if cnt != 1:
print "Error: check = %d != 1 after first get()" % cnt
return -1
cnt = RefCounter.put("X", False, "A")
270 if cnt != 0:
print "Error: count = %d != 0 after get-put" % cnt
return -1
(cnt, bcnt) = RefCounter.check("X", "A")
274 if cnt != 0:
print "Error: check = %d != 0 after get-put" % cnt
return -1
cnt = RefCounter.get("X", False, "A")
279 if cnt != 1:
print "Error: count = %d != 1 after get-put-get" % cnt
return -1
cnt = RefCounter.get("X", False, "A")
284 if cnt != 2:
print "Error: count = %d != 2 after second get()" % cnt
return -1
cnt = RefCounter.get("X", False, "A")
289 if cnt != 3:
print "Error: count = %d != 3 after third get()" % cnt
return -1
(cnt, bcnt) = RefCounter.check("X", "A")
293 if cnt != 3:
print "Error: check = %d != 3 after third get()" % cnt
return -1
cnt = RefCounter.put("Y", False, "A")
298 if cnt != 0:
print "Error: count = %d != 0 after first put()" % cnt
return -1
(cnt, bcnt) = RefCounter.check("Y", "A")
302 if cnt != 0:
print "Error: check = %d != 0 after first put()" % cnt
return -1
cnt = RefCounter.put("X", False, "A")
307 if cnt != 2:
print "Error: count = %d != 2 after 3get-1put" % cnt
return -1
cnt = RefCounter.put("X", False, "A")
312 if cnt != 1:
print "Error: count = %d != 1 after 3get-2put" % cnt
return -1
cnt = RefCounter.get("X", False, "A")
317 if cnt != 2:
print "Error: count = %d != 2 after 4get-2put" % cnt
return -1
(cnt, bcnt) = RefCounter.check("X", "A")
321 if cnt != 2:
print "Error: check = %d != 2 after 4get-2put" % cnt
return -1
cnt = RefCounter.put("X", False, "A")
326 if cnt != 1:
print "Error: count = %d != 0 after 4get-3put" % cnt
return -1
cnt = RefCounter.put("X", False, "A")
331 if cnt != 0:
print "Error: count = %d != 0 after 4get-4put" % cnt
return -1
(cnt, bcnt) = RefCounter.check("X", "A")
335 if cnt != 0:
print "Error: check = %d != 0 after 4get-4put" % cnt
return -1
# B
cnt = RefCounter.put("Z", False, "B")
341 if cnt != 0:
print "Error: count = %d != 0 after new put()" % cnt
return -1
cnt = RefCounter.get("Z", False, "B")
346 if cnt != 1:
print "Error: count = %d != 1 after put-get" % cnt
return -1
cnt = RefCounter.put("Z", False, "B")
351 if cnt != 0:
print "Error: count = %d != 0 after put-get-put" % cnt
return -1
(cnt, bcnt) = RefCounter.check("Z", "B")
355 if cnt != 0:
print "Error: check = %d != 0 after put-get-put" % cnt
return -1
cnt = RefCounter.get("Z", False, "B")
360 if cnt != 1:
print "Error: count = %d != 1 after put-get-put-get" % cnt
return -1
(cnt, bcnt) = RefCounter.check("Z", "B")
364 if cnt != 1:
print "Error: check = %d != 1 after put-get-put-get" % cnt
return -1
# set
(cnt, bcnt) = RefCounter.check("a/b")
370 if cnt != 0:
print "Error: count = %d != 0 initially" % cnt
return -1
RefCounter.set("a/b", 2, 0)
(cnt, bcnt) = RefCounter.check("a/b")
375 if cnt != 2 or bcnt != 0:
print "Error: count = (%d,%d) != (2,0) after set(2,0)" % (cnt, bcnt)
return -1
cnt = RefCounter.put("a/b", False)
379 if cnt != 1:
print "Error: count = %d != 1 after set(2)-put" % cnt
return -1
cnt = RefCounter.get("a/b", False)
383 if cnt != 2:
print "Error: count = %d != 2 after set(2)-put-get" % cnt
return -1
RefCounter.set("a/b", 100, 0)
(cnt, bcnt) = RefCounter.check("a/b")
388 if cnt != 100 or bcnt != 0:
print "Error: cnt,bcnt = (%d,%d) != (100,0) after set(100,0)" % \
(cnt, bcnt)
return -1
cnt = RefCounter.get("a/b", False)
393 if cnt != 101:
print "Error: count = %d != 101 after get" % cnt
return -1
RefCounter.set("a/b", 100, 1)
(cnt, bcnt) = RefCounter.check("a/b")
398 if cnt != 100 or bcnt != 1:
print "Error: cnt,bcnt = (%d,%d) != (100,1) after set(100,1)" % \
(cnt, bcnt)
return -1
RefCounter.reset("a/b")
(cnt, bcnt) = RefCounter.check("a/b")
404 if cnt != 0:
print "Error: check = %d != 0 after reset" % cnt
return -1
# binary
cnt = RefCounter.get("A", True)
410 if cnt != 1:
print "Error: count = %d != 1 after get(bin)" % cnt
return -1
cnt = RefCounter.get("A", True)
414 if cnt != 1:
print "Error: count = %d != 1 after get(bin)*2" % cnt
return -1
cnt = RefCounter.put("A", True)
418 if cnt != 0:
print "Error: count = %d != 0 after get(bin)*2-put(bin)" % cnt
return -1
cnt = RefCounter.put("A", True)
422 if cnt != 0:
print "Error: count = %d != 0 after get(bin)*2-put(bin)*2" % cnt
return -1
try:
RefCounter.set("A", 0, 2)
print "Error: set(0,2) was allowed"
return -1
except RefCounterException:
pass
cnt = RefCounter.get("A", True)
432 if cnt != 1:
print "Error: count = %d != 1 after get(bin)" % cnt
return -1
cnt = RefCounter.get("A", False)
436 if cnt != 2:
print "Error: count = %d != 2 after get(bin)-get" % cnt
return -1
cnt = RefCounter.get("A", False)
440 if cnt != 3:
print "Error: count = %d != 3 after get(bin)-get-get" % cnt
return -1
cnt = RefCounter.get("A", True)
444 if cnt != 3:
print "Error: count = %d != 3 after get(bin)-get*2-get(bin)" % cnt
return -1
cnt = RefCounter.put("A", False)
448 if cnt != 2:
print "Error: count = %d != 2 after get(bin)*2-get*2-put" % cnt
return -1
cnt = RefCounter.put("A", True)
452 if cnt != 1:
print "Error: cnt = %d != 1 after get(b)*2-get*2-put-put(b)" % cnt
return -1
cnt = RefCounter.put("A", False)
456 if cnt != 0:
print "Error: cnt = %d != 0 after get(b)*2-get*2-put*2-put(b)" % cnt
return -1
# names
cnt = RefCounter.get("Z", False)
462 if cnt != 1:
print "Error: count = %d != 1 after get (no ns 1)" % cnt
return -1
cnt = RefCounter.get("Z/", False)
467 if cnt != 1:
print "Error: count = %d != 1 after get (no ns 2)" % cnt
return -1
cnt = RefCounter.get("/Z", False)
472 if cnt != 1:
print "Error: count = %d != 1 after get (no ns 3)" % cnt
return -1
cnt = RefCounter.get("/Z/*/?/\\", False)
477 if cnt != 1:
print "Error: count = %d != 1 after get (no ns 4)" % cnt
return -1
cnt = RefCounter.get("Z", False)
482 if cnt != 2:
print "Error: count = %d != 2 after get (no ns 1)" % cnt
return -1
cnt = RefCounter.get("Z/", False)
487 if cnt != 2:
print "Error: count = %d != 2 after get (no ns 2)" % cnt
return -1
cnt = RefCounter.get("/Z", False)
492 if cnt != 2:
print "Error: count = %d != 2 after get (no ns 3)" % cnt
return -1
cnt = RefCounter.get("/Z/*/?/\\", False)
497 if cnt != 2:
print "Error: count = %d != 2 after get (no ns 4)" % cnt
return -1
# resetAll
RefCounter.resetAll("B")
cnt = RefCounter.get("Z", False, "B")
504 if cnt != 1:
print "Error: count = %d != 1 after resetAll-get" % cnt
return -1
cnt = RefCounter.get("Z", False, "C")
509 if cnt != 1:
print "Error: count = %d != 1 after C.get" % cnt
return -1
RefCounter.resetAll("B")
cnt = RefCounter.get("Z", False, "B")
515 if cnt != 1:
print "Error: count = %d != 1 after second resetAll-get" % cnt
return -1
cnt = RefCounter.get("Z", False, "C")
520 if cnt != 2:
print "Error: count = %d != 2 after second C.get" % cnt
return -1
RefCounter.resetAll("D")
RefCounter.resetAll()
cnt = RefCounter.put("Z", False, "B")
527 if cnt != 0:
print "Error: count = %d != 0 after resetAll-put" % cnt
return -1
cnt = RefCounter.put("Z", False, "C")
532 if cnt != 0:
print "Error: count = %d != 0 after C.resetAll-put" % cnt
return -1
RefCounter.resetAll()
return 0
_runTests = staticmethod(_runTests)
542if __name__ == '__main__':
print "Running unit tests..."
try:
if RefCounter._runTests() == 0:
print "All done, no errors"
except RefCounterException, e:
print "FAIL: Got exception: %s" % e
raise
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