class StateBasedChainer(MultiTargetChainer):
"""<class maturity="stable" abstract="yes">
<summary>
Class encapsulating connection establishment with multiple
target addresses and keeping down state between connects.
</summary>
<description>
<para>
This class encapsulates a real TCP/IP connection
establishment, and is used when a top-level proxy wants to
perform chaining. In addition to ConnectChainer, this class
adds the capability to perform stateful, load balance
server connections among a set of IP addresses.
</para>
<note>
<para>Both the <link linkend="python.Chainer.FailoverChainer">FailoverChainer</link>
and <link linkend="python.Chainer.RoundRobinChainer">RoundRobinChainer</link>
classes are derived from StateBasedChainer.</para>
</note>
</description>
<metainfo>
<attributes>
<attribute internal="yes">
<name>state</name>
<type></type>
<description>Down state of target hosts.
</description>
</attribute>
</attributes>
</metainfo>
</class>
"""
def __init__(self,
protocol=ZD_PROTO_AUTO,
timeout_connect=None,
timeout_state=None):
"""<method maturity="stable">
<summary>
Constructor to initialize a StateBasedChainer instance.
</summary>
<description>
<para>
This constructor initializes a StateBasedChainer class by
filling arguments with appropriate values and calling the
inherited constructor.
</para>
</description>
<metainfo>
<arguments>
<argument maturity="stable">
<name>protocol</name>
<type>
<link id="zorp.proto.id"/>
</type>
<default>ZD_PROTO_AUTO</default>
<description>
Optional, specifies connection protocol (<parameter>
ZD_PROTO_TCP</parameter> or <parameter>ZD_PROTO_UDP
</parameter>), when not specified it
defaults to the same protocol used on the
client side.
</description>
</argument>
<argument>
<name>timeout_connect</name>
<type>
<integer/>
</type>
<default>30000</default>
<description>
Specifies connection timeout to be used when
connecting to the target server.
</description>
</argument>
<argument>
<name>timeout_state</name>
<type>
<integer/>
</type>
<default>60000</default>
<description>
The down state of remote hosts is kept for this interval in miliseconds.
</description>
</argument>
</arguments>
</metainfo>
</method>
"""
MultiTargetChainer.__init__(self, protocol, timeout_connect)
if not timeout_state:
timeout_state = 60000
self.state = TimedCache('chainer-state',
int((timeout_state + 999) / 1000),
update_stamp=FALSE)
def getNextTarget(self, session):
"""<method internal="yes">
</method>
"""
while 1:
(target_local,
target_remote) = MultiTargetChainer.getNextTarget(self, session)
if not target_remote:
# we enumerated all targets
try:
session.chainer_targets_enumerated = session.chainer_targets_enumerated + 1
except AttributeError:
session.chainer_targets_enumerated = 1
if not self.state or session.chainer_targets_enumerated == 2:
# we enumerated all our targets twice, once
# with state held, and then all state
# cleared, we were not successful, terminate
# target iteration
log(
None, CORE_MESSAGE, 4,
"All destinations are down for two full iterations, giving up;"
)
return (None, None)
## LOG ##
# This message reports that the remote end is down and Zorp stores the
# down state of the remote end, so Zorp wont try to connect to it within the
# timeout latter.
##
log(
None, CORE_MESSAGE, 4,
"All destinations are down, clearing cache and trying again;"
)
# we enumerated all targets, and all of them were
# down, clear our state and try once more
self.state.clear()
self.restart(session)
continue
is_host_down = self.state.lookup(target_remote.ip_s)
if not is_host_down:
return (target_local, target_remote)
else:
## LOG ##
# This message reports that the remote end is down, but Zorp does not store the
# down state of the remote end, so Zorp will try to connect to it next time.
##
log(session.session_id, CORE_MESSAGE, 4,
"Destination is down, skipping; remote='%s'",
(target_remote, ))
def disableTarget(self, session, target_local, target_remote):
"""<method internal="yes">
</method>
"""
## LOG ##
# This message reports that the remote end is down and Zorp stores the
# down state of the remote end, so Zorp wont try to connect to it within the
# timeout latter.
##
log(session.session_id, CORE_MESSAGE, 4,
"Destination is down, keeping state; remote='%s'",
(target_remote, ))
self.state.store(target_remote.ip_s, 1)
class StateBasedChainer(MultiTargetChainer):
"""<class maturity="stable" abstract="yes">
<summary>
Class encapsulating connection establishment with multiple
target addresses and keeping down state between connects.
</summary>
<description>
<para>
This class encapsulates a real TCP/IP connection
establishment, and is used when a top-level proxy wants to
perform chaining. In addition to ConnectChainer, this class
adds the capability to perform stateful, load balance
server connections among a set of IP addresses.
</para>
<note>
<para>Both the <link linkend="python.Chainer.FailoverChainer">FailoverChainer</link>
and <link linkend="python.Chainer.RoundRobinChainer">RoundRobinChainer</link>
classes are derived from StateBasedChainer.</para>
</note>
</description>
<metainfo>
<attributes>
<attribute internal="yes">
<name>state</name>
<type></type>
<description>Down state of target hosts.
</description>
</attribute>
</attributes>
</metainfo>
</class>
"""
def __init__(self, protocol=ZD_PROTO_AUTO, timeout_connect=None, timeout_state=None):
"""<method maturity="stable">
<summary>
Constructor to initialize a StateBasedChainer instance.
</summary>
<description>
<para>
This constructor initializes a StateBasedChainer class by
filling arguments with appropriate values and calling the
inherited constructor.
</para>
</description>
<metainfo>
<arguments>
<argument maturity="stable">
<name>protocol</name>
<type>
<link id="zorp.proto.id"/>
</type>
<default>ZD_PROTO_AUTO</default>
<description>
Optional, specifies connection protocol (<parameter>
ZD_PROTO_TCP</parameter> or <parameter>ZD_PROTO_UDP
</parameter>), when not specified it
defaults to the same protocol used on the
client side.
</description>
</argument>
<argument>
<name>timeout_connect</name>
<type>
<integer/>
</type>
<default>30000</default>
<description>
Specifies connection timeout to be used when
connecting to the target server.
</description>
</argument>
<argument>
<name>timeout_state</name>
<type>
<integer/>
</type>
<default>60000</default>
<description>
The down state of remote hosts is kept for this interval in miliseconds.
</description>
</argument>
</arguments>
</metainfo>
</method>
"""
MultiTargetChainer.__init__(self, protocol, timeout_connect)
if not timeout_state:
timeout_state = 60000
self.state = TimedCache('chainer-state', int((timeout_state + 999) / 1000), update_stamp=FALSE)
def getNextTarget(self, session):
"""<method internal="yes">
</method>
"""
while 1:
(target_local, target_remote) = MultiTargetChainer.getNextTarget(self, session)
if not target_remote:
# we enumerated all targets
try:
session.chainer_targets_enumerated = session.chainer_targets_enumerated + 1
except AttributeError:
session.chainer_targets_enumerated = 1
if not self.state or session.chainer_targets_enumerated == 2:
# we enumerated all our targets twice, once
# with state held, and then all state
# cleared, we were not successful, terminate
# target iteration
log(None, CORE_MESSAGE, 4, "All destinations are down for two full iterations, giving up;")
return (None, None)
## LOG ##
# This message reports that the remote end is down and Zorp stores the
# down state of the remote end, so Zorp wont try to connect to it within the
# timeout latter.
##
log(None, CORE_MESSAGE, 4, "All destinations are down, clearing cache and trying again;")
# we enumerated all targets, and all of them were
# down, clear our state and try once more
self.state.clear()
self.restart(session)
continue
is_host_down = self.state.lookup(target_remote.ip_s)
if not is_host_down:
return (target_local, target_remote)
else:
## LOG ##
# This message reports that the remote end is down, but Zorp does not store the
# down state of the remote end, so Zorp will try to connect to it next time.
##
log(session.session_id, CORE_MESSAGE, 4, "Destination is down, skipping; remote='%s'", (target_remote,))
def disableTarget(self, session, target_local, target_remote):
"""<method internal="yes">
</method>
"""
## LOG ##
# This message reports that the remote end is down and Zorp stores the
# down state of the remote end, so Zorp wont try to connect to it within the
# timeout latter.
##
log(session.session_id, CORE_MESSAGE, 4, "Destination is down, keeping state; remote='%s'", (target_remote,))
self.state.store(target_remote.ip_s, 1)
