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# This file is part of Buildbot. Buildbot 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, version 2.
#
# 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.
#
# Copyright Buildbot Team Members
from __future__ import with_statement
from collections import deque
import os
import cPickle as pickle
from zope.interface import implements, Interface
def ReadFile(path):
with open(path, 'rb') as f:
return f.read()
def WriteFile(path, buf):
with open(path, 'wb') as f:
f.write(buf)
class IQueue(Interface):
"""Abstraction of a queue."""
def pushItem(item):
"""Adds an individual item to the end of the queue.
Returns an item if it was overflowed."""
def insertBackChunk(items):
"""Adds a list of items as the oldest entries.
Normally called in case of failure to process the data, queue the data
back so it can be retrieved at a later time.
Returns a list of items if it was overflowed."""
def popChunk(nbItems=None):
"""Pop many items at once. Defaults to self.maxItems()."""
def save():
"""Save the queue to storage if implemented."""
def items():
"""Returns items in the queue.
Warning: Can be extremely slow for queue on disk."""
def nbItems():
"""Returns the number of items in the queue."""
def maxItems():
"""Returns the maximum number of items this queue can hold."""
class MemoryQueue(object):
"""Simple length bounded queue using deque.
list.pop(0) operation is O(n) so for a 10000 items list, it can start to
be real slow. On the contrary, deque.popleft() is O(1) most of the time.
See http://docs.python.org/library/collections.html for more
information.
"""
implements(IQueue)
def __init__(self, maxItems=None):
self._maxItems = maxItems
if self._maxItems is None:
self._maxItems = 10000
self._items = deque()
def pushItem(self, item):
ret = None
if len(self._items) == self._maxItems:
ret = self._items.popleft()
self._items.append(item)
return ret
def insertBackChunk(self, chunk):
ret = None
excess = len(self._items) + len(chunk) - self._maxItems
if excess > 0:
ret = chunk[0:excess]
chunk = chunk[excess:]
self._items.extendleft(reversed(chunk))
return ret
def popChunk(self, nbItems=None):
if nbItems is None:
nbItems = self._maxItems
if nbItems > len(self._items):
items = list(self._items)
self._items = deque()
else:
items = []
for i in range(nbItems):
items.append(self._items.popleft())
return items
def save(self):
pass
def items(self):
return list(self._items)
def nbItems(self):
return len(self._items)
def maxItems(self):
return self._maxItems
class DiskQueue(object):
"""Keeps a list of abstract items and serializes it to the disk.
Use pickle for serialization."""
implements(IQueue)
def __init__(self, path, maxItems=None, pickleFn=pickle.dumps,
unpickleFn=pickle.loads):
"""
@path: directory to save the items.
@maxItems: maximum number of items to keep on disk, flush the
older ones.
@pickleFn: function used to pack the items to disk.
@unpickleFn: function used to unpack items from disk.
"""
self.path = path
self._maxItems = maxItems
if self._maxItems is None:
self._maxItems = 100000
if not os.path.isdir(self.path):
os.mkdir(self.path)
self.pickleFn = pickleFn
self.unpickleFn = unpickleFn
# Total number of items.
self._nbItems = 0
# The actual items id start at one.
self.firstItemId = 0
self.lastItemId = 0
self._loadFromDisk()
def pushItem(self, item):
ret = None
if self._nbItems == self._maxItems:
id = self._findNext(self.firstItemId)
path = os.path.join(self.path, str(id))
ret = self.unpickleFn(ReadFile(path))
os.remove(path)
self.firstItemId = id + 1
else:
self._nbItems += 1
self.lastItemId += 1
path = os.path.join(self.path, str(self.lastItemId))
if os.path.exists(path):
raise IOError('%s already exists.' % path)
WriteFile(path, self.pickleFn(item))
return ret
def insertBackChunk(self, chunk):
ret = None
excess = self._nbItems + len(chunk) - self._maxItems
if excess > 0:
ret = chunk[0:excess]
chunk = chunk[excess:]
for i in reversed(chunk):
self.firstItemId -= 1
path = os.path.join(self.path, str(self.firstItemId))
if os.path.exists(path):
raise IOError('%s already exists.' % path)
WriteFile(path, self.pickleFn(i))
self._nbItems += 1
return ret
def popChunk(self, nbItems=None):
if nbItems is None:
nbItems = self._maxItems
ret = []
for i in range(nbItems):
if self._nbItems == 0:
break
id = self._findNext(self.firstItemId)
path = os.path.join(self.path, str(id))
ret.append(self.unpickleFn(ReadFile(path)))
os.remove(path)
self._nbItems -= 1
self.firstItemId = id + 1
return ret
def save(self):
pass
def items(self):
"""Warning, very slow."""
ret = []
for id in range(self.firstItemId, self.lastItemId + 1):
path = os.path.join(self.path, str(id))
if os.path.exists(path):
ret.append(self.unpickleFn(ReadFile(path)))
return ret
def nbItems(self):
return self._nbItems
def maxItems(self):
return self._maxItems
#### Protected functions
def _findNext(self, id):
while True:
path = os.path.join(self.path, str(id))
if os.path.isfile(path):
return id
id += 1
return None
def _loadFromDisk(self):
"""Loads the queue from disk upto self.maxMemoryItems items into
self.items.
"""
def SafeInt(item):
try:
return int(item)
except ValueError:
return None
files = filter(None, [SafeInt(x) for x in os.listdir(self.path)])
files.sort()
self._nbItems = len(files)
if self._nbItems:
self.firstItemId = files[0]
self.lastItemId = files[-1]
class PersistentQueue(object):
"""Keeps a list of abstract items and serializes it to the disk.
It has 2 layers of queue, normally an in-memory queue and an on-disk queue.
When the number of items in the primary queue gets too large, the new items
are automatically saved to the secondary queue. The older items are kept in
the primary queue.
"""
implements(IQueue)
def __init__(self, primaryQueue=None, secondaryQueue=None, path=None):
"""
@primaryQueue: memory queue to use before buffering to disk.
@secondaryQueue: disk queue to use as permanent buffer.
@path: path is a shortcut when using default DiskQueue settings.
"""
self.primaryQueue = primaryQueue
if self.primaryQueue is None:
self.primaryQueue = MemoryQueue()
self.secondaryQueue = secondaryQueue
if self.secondaryQueue is None:
self.secondaryQueue = DiskQueue(path)
# Preload data from the secondary queue only if we know we won't start
# using the secondary queue right away.
if self.secondaryQueue.nbItems() < self.primaryQueue.maxItems():
self.primaryQueue.insertBackChunk(
self.secondaryQueue.popChunk(self.primaryQueue.maxItems()))
def pushItem(self, item):
# If there is already items in secondaryQueue, we'd need to pop them
# all to start inserting them into primaryQueue so don't bother and
# just push it in secondaryQueue.
if (self.secondaryQueue.nbItems() or
self.primaryQueue.nbItems() == self.primaryQueue.maxItems()):
item = self.secondaryQueue.pushItem(item)
if item is None:
return item
# If item is not None, secondaryQueue overflowed. We need to push it
# back to primaryQueue so the oldest item is dumped.
# Or everything fit in the primaryQueue.
return self.primaryQueue.pushItem(item)
def insertBackChunk(self, chunk):
ret = None
# Overall excess
excess = self.nbItems() + len(chunk) - self.maxItems()
if excess > 0:
ret = chunk[0:excess]
chunk = chunk[excess:]
# Memory excess
excess = (self.primaryQueue.nbItems() + len(chunk) -
self.primaryQueue.maxItems())
if excess > 0:
chunk2 = []
for i in range(excess):
chunk2.append(self.primaryQueue.items().pop())
chunk2.reverse()
x = self.primaryQueue.insertBackChunk(chunk)
assert x is None, "primaryQueue.insertBackChunk did not return None"
if excess > 0:
x = self.secondaryQueue.insertBackChunk(chunk2)
assert x is None, ("secondaryQueue.insertBackChunk did not return "
" None")
return ret
def popChunk(self, nbItems=None):
if nbItems is None:
nbItems = self.primaryQueue.maxItems()
ret = self.primaryQueue.popChunk(nbItems)
nbItems -= len(ret)
if nbItems and self.secondaryQueue.nbItems():
ret.extend(self.secondaryQueue.popChunk(nbItems))
return ret
def save(self):
self.secondaryQueue.insertBackChunk(self.primaryQueue.popChunk())
def items(self):
return self.primaryQueue.items() + self.secondaryQueue.items()
def nbItems(self):
return self.primaryQueue.nbItems() + self.secondaryQueue.nbItems()
def maxItems(self):
return self.primaryQueue.maxItems() + self.secondaryQueue.maxItems()
class IndexedQueue(object):
"""Adds functionality to a IQueue object to track its usage.
Adds a new member function getIndex() and modify popChunk() and
insertBackChunk() to keep a virtual pointer to the queue's first entry
index."""
implements(IQueue)
def __init__(self, queue):
# Copy all the member functions from the other object that this class
# doesn't already define.
assert IQueue.providedBy(queue)
def Filter(m):
return (m[0] != '_' and callable(getattr(queue, m))
and not hasattr(self, m))
for member in filter(Filter, dir(queue)):
setattr(self, member, getattr(queue, member))
self.queue = queue
self._index = 0
def getIndex(self):
return self._index
def popChunk(self, *args, **kwargs):
items = self.queue.popChunk(*args, **kwargs)
if items:
self._index += len(items)
return items
def insertBackChunk(self, items):
self._index -= len(items)
ret = self.queue.insertBackChunk(items)
if ret:
self._index += len(ret)
return ret
def ToIndexedQueue(queue):
"""If the IQueue wasn't already a IndexedQueue, makes it an IndexedQueue."""
if not IQueue.providedBy(queue):
raise TypeError("queue doesn't implement IQueue", queue)
if isinstance(queue, IndexedQueue):
return queue
return IndexedQueue(queue)
# vim: set ts=4 sts=4 sw=4 et:
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