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#!/usr/bin/env python
from collections import namedtuple
import struct
import time
import glob
import os
import logging
class Constants:
DB_MAX_NAME_LENGTH = 10
DB_WRITEBUF_LENGTH = 10
DBDAY_FORMAT_DAY = "%d%m%Y"
DB_OPEN_FILES = 5
INT_MILLI = 1
INT_SEC = 1000
INT_MIN = 60 * INT_SEC
INT_HOUR = 60 * INT_MIN
INT_DAY = 24 * INT_HOUR
INT_WEEK = 7 * INT_DAY
INT_MONTH = 31 * INT_DAY
INT_YEAR = 365 * INT_DAY
C = Constants
def time_ms():
return int(time.time() * 1000)
class DB(object):
def __init__(self, interval, fileinterval, directory, name):
assert len(name) <= Constants.DB_MAX_NAME_LENGTH, \
"name must be smaller than {0} (is {1})".format(Constants.DB_MAX_NAME_LENGTH, len(name))
self.interval = interval
self.fileinterval = fileinterval
self.directory = directory
self.name = name
self.isize = self.item_size() # item_size
self._files = {}
self._write_buf = {}
self.last_access = []
for path in glob.glob(self.directory + os.path.sep + name + "*"):
dbday = DBSegment.fopen(path, self)
self._files[dbday.filekey] = dbday
def __getitem__(self, key):
return self.get(key)
def get(self, key):
raise NotImplementedError()
def _get(self, key):
if not isinstance(key, int) and not isinstance(key, long):
raise TypeError("DB keys must be millisecond timestamps (int)")
logging.debug("get -> key %s fileinterval %s interval %s", key, self.fileinterval, self.interval)
filekey = self._calc_segment_key(key)
key = self._calc_key(key)
logging.debug("get => filekey %s key %s", filekey, key )
if (filekey, key) in self._write_buf.keys():
logging.debug("Write-Cache hit %s", key)
return self._write_buf[(filekey, key)]
db_segment = self.get_segment(filekey)
return db_segment[key]
def __setitem__(self, key, value):
return self.set(key, value)
def set(self, key, value):
raise NotImplementedError()
def _set(self, key, value):
if not isinstance(key, int) and not isinstance(key, long):
raise TypeError("DB keys must be millisecond timestamps (int)")
logging.debug("get -> key %s fileinterval %s interval %s", key, self.fileinterval, self.interval)
filekey = self._calc_segment_key(key)
key = self._calc_key(key)
logging.debug("get => filekey %s key %s", filekey, key )
self._write_buf[(filekey, key)] = value
if len(self._write_buf) > Constants.DB_WRITEBUF_LENGTH:
self._flush_buf()
return value
def get_segment(self, filekey):
if filekey in self._files.keys():
return self._files[filekey]
else:
header = DBSegment.header( filekey=filekey,
isize=self.isize, interval=self.interval,
fileinterval=self.fileinterval, dbname=self.name)
path = self.directory + os.path.sep + self.name + str(filekey)
db_segment = DBSegment(self, path, header)
logging.info("New File %s", db_segment.path)
self._files[filekey] = db_segment
return db_segment
def _calc_key(self, key):
return int( (key % self.fileinterval) / self.interval)
def _calc_segment_key(self, key):
return int( key / self.fileinterval )
def _flush_buf(self):
logging.debug("flush")
keys = self._write_buf.keys()
keys.sort()
for (filekey,key) in keys:
db_segment = self.get_segment(filekey)
db_segment[key] = self._write_buf[(filekey, key)]
self._write_buf.clear()
def close(self):
self._flush_buf()
def item_size(self):
""""""
raise NotImplementedError()
class InvalidSegmentError(Exception):
def __init__(self, header, *args):
Exception.__init__(self, *args)
self.header = header
class _LazyEval(object):
def __init__(self, func, *args, **kwargs):
self.func, self.args, self.kwargs = func, args, kwargs
def __str__(self):
return self.func(*self.args, **self.kwargs)
def _to_hexstring(input_string):
def _do(string):
return " ".join(map(lambda c:"%02x"%ord(c), string)).upper()
return _LazyEval(_do, input_string)
class DBSegment(object):
header = namedtuple('Header', 'filekey isize interval fileinterval dbname')
header_format = "iiii%dp"%Constants.DB_MAX_NAME_LENGTH
header_size = struct.calcsize( "iiii%dp"%Constants.DB_MAX_NAME_LENGTH )
@staticmethod
def fopen(path, db):
filekey = int( os.path.basename(path)[len(db.name):] )
with file(path, "rb") as fh:
header = DBSegment.header._make( struct.unpack( DBSegment.header_format, fh.read( DBSegment.header_size ) ) )
if not (header.filekey == filekey
and header.interval == db.interval
and header.fileinterval == db.fileinterval
and header.dbname == db.name):
raise InvalidSegmentError(header)
f = DBSegment(db, path, header)
return f
def __init__(self, db, path, header):
self.db = db
self.path = path
self.header = header
self.filekey = header.filekey
if not os.path.exists(self.path):
logging.info("Write header in new file %s", self.path)
self.fh = file(self.path, "wb")
self.fh.write( struct.pack( DBSegment.header_format, *list(header) ) )
end = ( DBSegment.header_size +
( self.db.fileinterval / self.db.interval ) * self.db.isize)
self.fh.seek( end )
self.fh.write( "\0" )
self.fh.close()
self.fh = None
self.open()
def __setitem__(self, key, data):
logging.debug("Set %s = %s", key, _to_hexstring(data))
self._seek(key)
self.fh.write( data[:self.db.isize] )
self.lastpos = self.fh.tell()
def __getitem__(self, key):
self._seek(key)
data = self.fh.read( self.db.isize )
self.lastpos = self.fh.tell()
logging.debug("Get %s => %s", key, _to_hexstring(data))
return data
def _seek(self, key):
offset = DBSegment.header_size + \
key * self.db.isize
if self.lastpos == offset:
logging.debug("continue at %s", self.lastpos)
else:
logging.debug("seek to %s in %s instance %s (lastpos = %s)", offset, self.path, id(self), self.lastpos)
if not self.fh:
self.open()
self.fh.seek( offset )
def open(self):
if not self.fh:
logging.debug("Open %s",self.path)
self.fh = file(self.path, "r+b")
self.lastpos = self.fh.tell()
def close(self):
logging.info("Close %s instance %s", self.path, id(self))
if self.fh:
self.fh.close()
self.fh = None
class DBInt(DB):
payload = namedtuple("payload", "x y z")
payload_format = "iii"
def get(self, key):
return DBInt.payload._make(
struct.unpack(
DBInt.payload_format, self._get(key) ) )
def set(self, key, value):
return self._set(key,
struct.pack(DBInt.payload_format, *list(value)))
def item_size(self):
return struct.calcsize( DBInt.payload_format )
class DBSimpleInt(DB):
def get(self, key):
return struct.unpack("i", self._get(key))[0]
def set(self, key, value):
return self._set(key,
struct.pack("i", value))
def item_size(self):
return struct.calcsize( "i" )
import random
if __name__ == "__main__":
#logging.basicConfig(level=logging.DEBUG)
logging.basicConfig(level=logging.INFO)
#logging.basicConfig(level=logging.ERROR)
# Alle 5 sek.
start = time_ms()
stop = time_ms() + Constants.INT_DAY*2
db = DBSimple(1000 * Constants.INT_MILLI, Constants.INT_DAY, ".", "testdb")
rand = 123456
for ts in range(start, stop, 1000*Constants.INT_MILLI):
db[ts] = -ts % rand
assert db[ts] == -ts%rand, "%s != %s"%(db[ts], ts)
r = range(start, stop, 1000*Constants.INT_MILLI)
r.reverse()
for ts in r:
assert db[ts] == -ts%rand, "%s != %s"%(db[ts], -ts%rand)
db.close()
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