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"""
"""
# Created on 2014.03.14
#
# Author: Giovanni Cannata
#
# Copyright 2015 Giovanni Cannata
#
# This file is part of ldap3.
#
# ldap3 is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# ldap3 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with ldap3 in the COPYING and COPYING.LESSER files.
# If not, see <http://www.gnu.org/licenses/>.
from datetime import datetime, MINYEAR
from os import linesep
from random import randint
from time import sleep
from .. import FIRST, ROUND_ROBIN, RANDOM, POOLING_STRATEGIES, SEQUENCE_TYPES, STRING_TYPES, get_config_parameter
from .exceptions import LDAPUnknownStrategyError, LDAPServerPoolError, LDAPServerPoolExhaustedError
from .server import Server
from ..utils.log import log, log_enabled, ERROR, BASIC, NETWORK
class ServerPoolState(object):
def __init__(self, server_pool):
self.servers = [] # each element is a list: [server, last_checked_time, available]
self.strategy = server_pool.strategy
self.server_pool = server_pool
self.last_used_server = 0
self.refresh()
self.initialize_time = datetime.now()
if log_enabled(BASIC):
log(BASIC, 'instantiated ServerPoolState: <%r>', self)
def __str__(self):
s = 'servers: ' + linesep
if self.servers:
for server in self.servers:
s += str(server[0]) + linesep
else:
s += 'None' + linesep
s += 'Pool strategy: ' + str(self.strategy) + linesep
s += ' - Last used server: ' + ('None' if self.last_used_server == -1 else str(self.servers[self.last_used_server][0]))
return s
def refresh(self):
self.servers = []
for server in self.server_pool.servers:
self.servers.append([server, datetime(MINYEAR, 1, 1), True]) # server, smallest date ever, supposed available
self.last_used_server = randint(0, len(self.servers) - 1)
def get_current_server(self):
return self.servers[self.last_used_server][0]
def get_server(self):
if self.servers:
if self.server_pool.strategy == FIRST:
if self.server_pool.active:
# returns the first active server
self.last_used_server = self.find_active_server(starting=0)
else:
# returns always the first server - no pooling
self.last_used_server = 0
elif self.server_pool.strategy == ROUND_ROBIN:
if self.server_pool.active:
# returns the next active server in a circular range
self.last_used_server = self.find_active_server(self.last_used_server + 1)
else:
# returns the next server in a circular range
self.last_used_server = self.last_used_server + 1 if (self.last_used_server + 1) < len(self.servers) else 0
elif self.server_pool.strategy == RANDOM:
if self.server_pool.active:
self.last_used_server = self.find_active_random_server()
else:
# returns a random server in the pool
self.last_used_server = randint(0, len(self.servers) - 1)
else:
if log_enabled(ERROR):
log(ERROR, 'unknown server pooling strategy <%s>', self.server_pool.strategy)
raise LDAPUnknownStrategyError('unknown server pooling strategy')
if log_enabled(BASIC):
log(BASIC, 'server returned from Server Pool: <%s>', self.last_used_server)
return self.servers[self.last_used_server][0]
else:
if log_enabled(ERROR):
log(ERROR, 'no servers in Server Pool <%s>', self)
raise LDAPServerPoolError('no servers in server pool')
def find_active_random_server(self):
counter = self.server_pool.active # can be True for "forever" or the number of cycles to try
while counter:
if log_enabled(NETWORK):
log(NETWORK, 'entering loop for finding active server in pool <%s>', self)
temp_list = self.servers[:] # copy
while temp_list:
# pops a random server from a temp list and checks its
# availability, if not available tries another one
server = temp_list.pop(randint(0, len(temp_list) - 1))
if not server[2]: # server is offline
if (isinstance(self.server_pool.exhaust, bool) and self.server_pool.exhaust) or (datetime.now() - server[1]).seconds < self.server_pool.exhaust: # keeps server offline
if log_enabled(NETWORK):
log(NETWORK, 'server <%s> excluded from checking because is offline', server[0])
continue
if log_enabled(NETWORK):
log(NETWORK, 'server <%s> reinserted in pool', server[0])
server[1] = datetime.now()
if log_enabled(NETWORK):
log(NETWORK, 'checking server <%s> for availability', server[0])
if server[0].check_availability():
# returns a random active server in the pool
server[2] = True
return self.servers.index(server)[0]
else:
server[2] = False
if not isinstance(self.server_pool.active, bool):
counter -= 1
if log_enabled(ERROR):
log(ERROR, 'no random active server available in Server Pool <%s> after maximum number of tries', self)
raise LDAPServerPoolExhaustedError('no random active server available in server pool after maximum number of tries')
def find_active_server(self, starting):
counter = self.server_pool.active # can be True for "forever" or the number of cycles to try
if starting >= len(self.servers):
starting = 0
while counter:
if log_enabled(NETWORK):
log(NETWORK, 'entering loop number <%s> for finding active server in pool <%s>', counter, self)
index = -1
pool_size = len(self.servers)
while index < pool_size - 1:
index += 1
offset = index + starting if index + starting < pool_size else index + starting - pool_size
if not self.servers[offset][2]: # server is offline
if (isinstance(self.server_pool.exhaust, bool) and self.server_pool.exhaust) or (datetime.now() - self.servers[offset][1]).seconds < self.server_pool.exhaust: # keeps server offline
if log_enabled(NETWORK):
if isinstance(self.server_pool.exhaust, bool):
log(NETWORK, 'server <%s> excluded from checking because is offline', self.servers[offset][0])
else:
log(NETWORK, 'server <%s> excluded from checking because is offline for %d seconds', self.servers[offset][0], (self.server_pool.exhaust - (datetime.now() - self.servers[offset][1]).seconds))
continue
if log_enabled(NETWORK):
log(NETWORK, 'server <%s> reinserted in pool', self.servers[offset][0])
self.servers[offset][1] = datetime.now()
if log_enabled(NETWORK):
log(NETWORK, 'checking server <%s> for availability', self.servers[offset][0])
if self.servers[offset][0].check_availability():
self.servers[offset][2] = True
return offset
else:
self.servers[offset][2] = False # sets server offline
if not isinstance(self.server_pool.active, bool):
counter -= 1
if log_enabled(NETWORK):
log(NETWORK, 'waiting for %d seconds before retrying pool servers cycle', get_config_parameter('POOLING_LOOP_TIMEOUT'))
sleep(get_config_parameter('POOLING_LOOP_TIMEOUT'))
if log_enabled(ERROR):
log(ERROR, 'no active server available in Server Pool <%s> after maximum number of tries', self)
raise LDAPServerPoolExhaustedError('no active server available in server pool after maximum number of tries')
def __len__(self):
return len(self.servers)
class ServerPool(object):
def __init__(self,
servers=None,
pool_strategy=ROUND_ROBIN,
active=True,
exhaust=False):
if pool_strategy not in POOLING_STRATEGIES:
if log_enabled(ERROR):
log(ERROR, 'unknown pooling strategy <%s>', pool_strategy)
raise LDAPUnknownStrategyError('unknown pooling strategy')
if exhaust and not active:
if log_enabled(ERROR):
log(ERROR, 'cannot instantiate pool with exhaust and not active')
raise LDAPServerPoolError('pools can be exhausted only when checking for active servers')
self.servers = []
self.pool_states = dict()
self.active = active
self.exhaust = exhaust
if isinstance(servers, SEQUENCE_TYPES + (Server, )):
self.add(servers)
elif isinstance(servers, STRING_TYPES):
self.add(Server(servers))
self.strategy = pool_strategy
if log_enabled(BASIC):
log(BASIC, 'instantiated ServerPool: <%r>', self)
def __str__(self):
s = 'servers: ' + linesep
if self.servers:
for server in self.servers:
s += str(server) + linesep
else:
s += 'None' + linesep
s += 'Pool strategy: ' + str(self.strategy)
s += ' - ' + 'active: ' + (str(self.active) if self.active else 'False')
s += ' - ' + 'exhaust pool: ' + (str(self.exhaust) if self.exhaust else 'False')
return s
def __repr__(self):
r = 'ServerPool(servers='
if self.servers:
r += '['
for server in self.servers:
r += server.__repr__() + ', '
r = r[:-2] + ']'
else:
r += 'None'
r += ', pool_strategy={0.strategy!r}'.format(self)
r += ', active={0.active!r}'.format(self)
r += ', exhaust={0.exhaust!r}'.format(self)
r += ')'
return r
def __len__(self):
return len(self.servers)
def __getitem__(self, item):
return self.servers[item]
def __iter__(self):
return self.servers.__iter__()
def add(self, servers):
if isinstance(servers, Server):
if servers not in self.servers:
self.servers.append(servers)
elif isinstance(servers, STRING_TYPES):
self.servers.append(Server(servers))
elif isinstance(servers, SEQUENCE_TYPES):
for server in servers:
if isinstance(server, Server):
self.servers.append(server)
elif isinstance(server, STRING_TYPES):
self.servers.append(Server(server))
else:
if log_enabled(ERROR):
log(ERROR, 'element must be a server in Server Pool <%s>', self)
raise LDAPServerPoolError('server in ServerPool must be a Server')
else:
if log_enabled(ERROR):
log(ERROR, 'server must be a Server of a list of Servers when adding to Server Pool <%s>', self)
raise LDAPServerPoolError('server must be a Server or a list of Server')
for connection in self.pool_states:
# notifies connections using this pool to refresh
self.pool_states[connection].refresh()
def remove(self, server):
if server in self.servers:
self.servers.remove(server)
else:
if log_enabled(ERROR):
log(ERROR, 'server %s to be removed not in Server Pool <%s>', server, self)
raise LDAPServerPoolError('server not in server pool')
for connection in self.pool_states:
# notifies connections using this pool to refresh
self.pool_states[connection].refresh()
def initialize(self, connection):
pool_state = ServerPoolState(self)
# registers pool_state in ServerPool object
self.pool_states[connection] = pool_state
def get_server(self, connection):
if connection in self.pool_states:
return self.pool_states[connection].get_server()
else:
if log_enabled(ERROR):
log(ERROR, 'connection <%s> not in Server Pool State <%s>', connection, self)
raise LDAPServerPoolError('connection not in ServerPoolState')
def get_current_server(self, connection):
if connection in self.pool_states:
return self.pool_states[connection].get_current_server()
else:
if log_enabled(ERROR):
log(ERROR, 'connection <%s> not in Server Pool State <%s>', connection, self)
raise LDAPServerPoolError('connection not in ServerPoolState')
|
