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import bsddb
from _bsddb import DBNotFoundError
import json
import time
import os
import numpy
import struct
from threading import Lock
try:
from collections import OrderedDict
except ImportError:
from ordereddict import OrderedDict
__all__ = ['Datastore', 'Interval']
class UnknownTableError(Exception): pass
class EmptyTableError(Exception): pass
class ReadOnlyError(Exception): pass
class Interval:
MS=1
SEC=1000*MS
MIN=60*SEC
HOUR=60*MIN
DAY=24*HOUR
MONTH=30.5*DAY
YEAR=365*MONTH
class Datastore(object):
def __init__(self,directory,readonly=False,chunkInterval=Interval.DAY):
if not os.path.exists(directory):
raise Exception("No such directory {d}".format(d=directory))
self.directory = directory
self.readonly = readonly
self.chunkInterval = chunkInterval
self.tables = OrderedDict()
self.tableLock = Lock()
def openChunkTable(self, name, timestamp):
with self.tableLock:
chunkTimestamp = timestamp - (timestamp % self.chunkInterval)
key = "{n:s}:{ts:d}".format(n=name, ts=chunkTimestamp)
if key in self.tables:
return self.tables[key]
path_dir = os.path.join(self.directory, name)
if not os.path.exists(path_dir):
raise UnknownTableError("no table with name {0}".format(name))
path_time = time.strftime("%Y_%m_%d-%H_%M_%S",
time.gmtime(chunkTimestamp/Interval.SEC))
path = os.path.join(path_dir, path_time + ".bdb")
print "open key={k} open-files={c}".format(k=key,c=len(self.tables))
if len(self.tables) > 800:
while len(self.tables) > 500:
closekey = self.tables.keys()[0]
self.tables.pop( closekey )
print "closed key={name} open-files={c}".format(name=closekey,c=len(self.tables))
if self.readonly:
try:
self.tables[key] = bsddb.btopen(path,"r")
except bsddb.db.DBNoSuchFileError:
raise EmptyTableError(key)
else:
self.tables[key] = bsddb.btopen(path)
return self.tables[key]
def createTable(self, name, format):
if self.readonly:
raise ReadOnlyError()
with self.tableLock:
path_dir = os.path.join(self.directory, name)
if os.path.exists(path_dir):
raise Exception("table exists")
os.mkdir(path_dir)
configfile = open(os.path.join(path_dir, "config.json"), "w")
config = {'name':name, 'format':format, 'created':time.time()}
print "Create config={config}".format(config=config)
json.dump(config, configfile)
configfile.close()
def get_config(self, name):
with self.tableLock:
path_dir = os.path.join(self.directory, name)
if not os.path.exists(path_dir):
raise UnknownTableError(name)
return json.load(open(os.path.join(path_dir, "config.json"), "r"))
def has_table(self,name):
with self.tableLock:
return os.path.exists( os.path.join(self.directory, name) )
def _addValue(self, name, ts, value, format):
try:
t = self.openChunkTable(name, ts)
except UnknownTableError:
self.createTable(name, format)
t = self.openChunkTable(name, ts)
key = str(ts)
value = struct.pack(format, value)
t[key] = value
def addValueInt(self, name, ts, value): self._addValue(name, ts, value, "q")
def addValueString(self, name, ts, value): self._addValue(name, ts, value, "30s")
def addValueFloat(self, name, ts, value): self._addValue(name, ts, value, "d")
def get_range_n(self, name, start, end, number=500):
print "get_range_n start={s} end={e} number={n}".format(
s=start, e=end, n=number)
for kv in self.get_range(name, start, end,
step=long(numpy.ceil((end-start)/float(number)))):
yield kv
def get_range(self, name, start, end, step=None):
print "get_range name={n} start={s} end={e} step={p}({t})".format(
n=name, s=start, e=end, p=step, t=type(step))
assert step == None or step > 0
config = self.get_config(name)
unpackFunc = lambda v: struct.unpack(config['format'], v)[0]
currentChunk = start - (start % self.chunkInterval)
key = start
while key<=end:
try:
t = self.openChunkTable(name,currentChunk)
except EmptyTableError:
# if the current chunk is empty switch to the next
currentChunk += self.chunkInterval
key = currentChunk
continue
try:
key_b = str(key)
(key_b, value) = t.set_location(key_b)
key = long(key_b)
except DBNotFoundError:
# if a item does not exist it will point to the next item
# in sorted order. If event that does not exist something is terrible
# wrong and we continue with the next chunk
currentChunk += self.chunkInterval
key = currentChunk
continue
while key <= currentChunk + self.chunkInterval:
#print time.strftime("%c", time.gmtime(key/1000)), unpack(value)
yield (key, unpackFunc(value))
try:
if step:
key += step
key_b = str(key)
key_b, value = t.set_location(key_b)
else:
key_b, value = t.next()
key = long(key_b)
except DBNotFoundError,e:
# if key is not found then no data is
# left in this btree chunk
break
currentChunk += self.chunkInterval
def close(self):
with self.tableLock:
while len(self.tables) > 0:
closekey = self.tables.keys()[0]
self.tables.pop( closekey )
print "closed key={name} open-files={c}".format(name=closekey,c=len(self.tables))
# vim: autoindent tabstop=4 shiftwidth=4 expandtab softtabstop=4 filetype=python
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