First time I actually used a decorator. I knew about them, but I never thought of a use for them. Ok I am slow :)
from persistent import Persistent
from BTrees.LOBTree import LOBTree
from ZODB.POSException import ConflictError
import Queue
import transaction
import time
def transactionDecorator(fn):
def newfn(*args,**kwargs) :
while 1 :
try :
transaction.manager.begin()
result = fn(*args,**kwargs)
transaction.manager.commit()
return result
except ConflictError:
time.sleep(0.01)
except Exception,e:
transaction.manager.abort()
raise e
return newfn
class BTreeQueue(Persistent) :
def __init__(self):
self.bTree = LOBTree()
@transactionDecorator
def push(self,item):
key = None
try :
key = self.bTree.maxKey()
except ValueError :
key = 0
self.bTree.insert(key+1,item)
@transactionDecorator
def extend(self,items) :
start = None
try :
start = self.bTree.maxKey()
except ValueError :
start = 0
start += 1
result = {}
for i,key in enumerate(range(start,start+len(items))) :
result[key] = items[i]
self.bTree.update(result)
@transactionDecorator
def pop(self):
item = None
error = False
try :
key =self.bTree.minKey()
item = self.bTree.pop(key)
except ValueError :
error = True
finally :
if error :
raise Queue.Empty()
else :
return item
@transactionDecorator
def rotate(self):
"""pops a item then puts it on end again, returns value"""
item = None
error = False
key =self.bTree.minKey()
item = self.bTree.pop(key)
self.bTree.insert(self.bTree.maxKey()+1,item)
return item
@transactionDecorator
def count(self):
count = None
try :
count = self.bTree.maxKey() - self.bTree.minKey() + 1
except ValueError :
count = 0
return count
@transactionDecorator
def empty(self):
self.bTree.clear()
