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"""Gdbm database engine."""
try:
import gdbm as gdbm
_has_gdbm = True
except ImportError:
try:
import dbm.gnu as gdbm
_has_gdbm = True
except ImportError:
_has_gdbm = False
import time
import logging
import datetime
import threading
from pyzor.engines.common import Record, DBHandle, BaseEngine
def _dt_decode(datetime_str):
"""Decode a string into a datetime object."""
if datetime_str == 'None':
return None
try:
return datetime.datetime.strptime(datetime_str, "%Y-%m-%d %H:%M:%S.%f")
except ValueError:
return datetime.datetime.strptime(datetime_str, "%Y-%m-%d %H:%M:%S")
class GdbmDBHandle(BaseEngine):
absolute_source = True
handles_one_step = False
sync_period = 60
reorganize_period = 3600 * 24 # 1 day
fields = ('r_count', 'r_entered', 'r_updated',
'wl_count', 'wl_entered', 'wl_updated')
_fields = [('r_count', int),
('r_entered', _dt_decode),
('r_updated', _dt_decode),
('wl_count', int),
('wl_entered', _dt_decode),
('wl_updated', _dt_decode)]
this_version = '1'
log = logging.getLogger("pyzord")
def __init__(self, fn, mode, max_age=None):
self.max_age = max_age
self.db = gdbm.open(fn, mode)
self.reorganize_timer = None
self.sync_timer = None
self.start_reorganizing()
self.start_syncing()
def __iter__(self):
k = self.db.firstkey()
while k is not None:
yield k
k = self.db.nextkey(k)
def _iteritems(self):
for k in self:
try:
yield k, self._really_getitem(k)
except Exception as e:
self.log.warning("Invalid record %s: %s", k, e)
def iteritems(self):
return self._iteritems()
def items(self):
return list(self._iteritems())
def apply_method(self, method, varargs=(), kwargs=None):
if kwargs is None:
kwargs = {}
return apply(method, varargs, kwargs)
def __getitem__(self, key):
return self.apply_method(self._really_getitem, (key,))
def _really_getitem(self, key):
return GdbmDBHandle.decode_record(self.db[key])
def __setitem__(self, key, value):
self.apply_method(self._really_setitem, (key, value))
def _really_setitem(self, key, value):
self.db[key] = GdbmDBHandle.encode_record(value)
def __delitem__(self, key):
self.apply_method(self._really_delitem, (key,))
def _really_delitem(self, key):
del self.db[key]
def start_syncing(self):
if self.db:
self.apply_method(self._really_sync)
self.sync_timer = threading.Timer(self.sync_period,
self.start_syncing)
self.sync_timer.setDaemon(True)
self.sync_timer.start()
def _really_sync(self):
self.db.sync()
def start_reorganizing(self):
if not self.max_age:
return
if self.db:
self.apply_method(self._really_reorganize)
self.reorganize_timer = threading.Timer(self.reorganize_period,
self.start_reorganizing)
self.reorganize_timer.setDaemon(True)
self.reorganize_timer.start()
def _really_reorganize(self):
self.log.debug("reorganizing the database")
key = self.db.firstkey()
breakpoint = time.time() - self.max_age
while key is not None:
rec = self._really_getitem(key)
delkey = None
if int(time.mktime(rec.r_updated.timetuple())) < breakpoint:
self.log.debug("deleting key %s", key)
delkey = key
key = self.db.nextkey(key)
if delkey:
self._really_delitem(delkey)
self.db.reorganize()
@classmethod
def encode_record(cls, value):
values = [cls.this_version]
values.extend(["%s" % getattr(value, x) for x in cls.fields])
return ",".join(values)
@classmethod
def decode_record(cls, s):
try:
s = s.decode("utf8")
except UnicodeError:
raise StandardError("don't know how to handle db value %s" %
repr(s))
parts = s.split(',')
version = parts[0]
if len(parts) == 3:
dispatch = cls.decode_record_0
elif version == '1':
dispatch = cls.decode_record_1
else:
raise StandardError("don't know how to handle db value %s" %
repr(s))
return dispatch(s)
@staticmethod
def decode_record_0(s):
r = Record()
parts = s.split(',')
fields = ('r_count', 'r_entered', 'r_updated')
assert len(parts) == len(fields)
for i in range(len(parts)):
setattr(r, fields[i], int(parts[i]))
return r
@classmethod
def decode_record_1(cls, s):
r = Record()
parts = s.split(',')[1:]
assert len(parts) == len(cls.fields)
for part, field in zip(parts, cls._fields):
f, decode = field
setattr(r, f, decode(part))
return r
class ThreadedGdbmDBHandle(GdbmDBHandle):
"""Like GdbmDBHandle, but handles multi-threaded access."""
def __init__(self, fn, mode, max_age=None, bound=None):
self.db_lock = threading.Lock()
GdbmDBHandle.__init__(self, fn, mode, max_age=max_age)
def apply_method(self, method, varargs=(), kwargs=None):
if kwargs is None:
kwargs = {}
with self.db_lock:
return GdbmDBHandle.apply_method(self, method, varargs=varargs,
kwargs=kwargs)
# This won't work because the gdbm object needs to be in shared memory of the
# spawned processes.
# class ProcessGdbmDBHandle(ThreadedGdbmDBHandle):
# def __init__(self, fn, mode, max_age=None, bound=None):
# ThreadedGdbmDBHandle.__init__(self, fn, mode, max_age=max_age,
# bound=bound)
# self.db_lock = multiprocessing.Lock()
if not _has_gdbm:
handle = DBHandle(single_threaded=None,
multi_threaded=None,
multi_processing=None,
prefork=None)
else:
handle = DBHandle(single_threaded=GdbmDBHandle,
multi_threaded=ThreadedGdbmDBHandle,
multi_processing=None,
prefork=None)
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