org.jgroups.protocols

Class FILE_PING

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.Discovery

org.jgroups.protocols.FILE_PING

Direct Known Subclasses:

JDBC_PING, S3_PING

public class FILE_PING
extends Discovery

Simple discovery protocol which uses a file on shared storage such as an SMB share, NFS mount or S3. The local address information, e.g. UUID and physical addresses mappings are written to the file and the content is read and added to our transport's UUID-PhysicalAddress cache.

The design is at doc/design/FILE_PING.txt

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	FILE_PING.WriterTask

Nested classes/interfaces inherited from class org.jgroups.protocols.Discovery

Discovery.Responses

Field Summary

Fields

Modifier and Type	Field and Description
protected FilenameFilter	filter
protected long	interval
protected String	location
protected File	root_dir
protected static String	SUFFIX

Fields inherited from class org.jgroups.protocols.Discovery

break_on_coord_rsp, current_coord, force_sending_discovery_rsps, group_addr, is_coord, is_leaving, is_server, local_addr, members, num_discovery_requests, num_initial_members, num_initial_srv_members, ping_responses, return_entire_cache, stagger_timeout, timeout, timer, view

Fields inherited from class org.jgroups.stack.Protocol

down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
FILE_PING()

Method Summary

Methods

Modifier and Type	Method and Description
protected static String	addressAsString(Address address)
protected void	createRootDir()
Object	down(Event evt) An event is to be sent down the stack.
Collection<PhysicalAddress>	fetchClusterMembers(String cluster_name) Grab all current cluster members
protected void	handleView(View view)
void	init() Called after instance has been created (null constructor) and before protocol is started.
boolean	isDynamic()
protected List<PingData>	readAll(String clustername) Reads all information from the given directory under clustername
protected static PingData	readFile(File file)
protected void	remove(String clustername, Address addr)
boolean	sendDiscoveryRequestsInParallel() Whether or not to send each discovery request on a separate (timer) thread.
void	start() This method is called on a Channel.connect(String).
void	stop() This method is called on a Channel.disconnect().
protected void	writeToFile(PingData data, String clustername)

Methods inherited from class org.jgroups.protocols.Discovery

deserialize, discoveryRequestReceived, findAllViews, findAllViewsAsString, findInitialMembers, findInitialMembersAsString, findMembers, getCurrentCoord, getNumberOfDiscoveryRequestsSent, getNumInitialMembers, getTimeout, getView, getViewId, handleConnect, handleDisconnect, isMergeRunning, providedUpServices, resetStats, sendDiscoveryRequest, sendDiscoveryResponse, sendMcastDiscoveryRequest, serializeWithoutView, setForceSendingDiscoveryRsps, setNumInitialMembers, setTimeout, up

Methods inherited from class org.jgroups.stack.Protocol

destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedDownServices, requiredDownServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SUFFIX

protected static final String SUFFIX

See Also:

Constant Field Values

location

protected String location

interval

protected long interval

root_dir

protected File root_dir

filter

protected FilenameFilter filter

Constructor Detail

FILE_PING

public FILE_PING()

Method Detail

init

public void init()
          throws Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Discovery

Throws:

Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

start

public void start()
           throws Exception

Description copied from class: Protocol

This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.

Overrides:

start in class Discovery

Throws:

Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception

stop

public void stop()

Description copied from class: Protocol

This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

Overrides:

stop in class Discovery

isDynamic

public boolean isDynamic()

Specified by:

isDynamic in class Discovery

fetchClusterMembers

public Collection<PhysicalAddress> fetchClusterMembers(String cluster_name)

Description copied from class: Discovery

Grab all current cluster members

Specified by:

fetchClusterMembers in class Discovery

Returns:

A list of the cluster members (usually IpAddresses), or null if the transport is multicast-enabled. Returns an empty list if no cluster members could be found.

sendDiscoveryRequestsInParallel

public boolean sendDiscoveryRequestsInParallel()

Description copied from class: Discovery

Whether or not to send each discovery request on a separate (timer) thread. If disabled, a discovery request will be sent to all members fetched by Discovery.fetchClusterMembers(String) sequentially

Specified by:

sendDiscoveryRequestsInParallel in class Discovery

down

public Object down(Event evt)

Description copied from class: Discovery

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using PassDown. In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up(). The PING protocol is interested in several different down events, Event.FIND_INITIAL_MBRS - sent by the GMS layer and expecting a GET_MBRS_OK Event.TMP_VIEW and Event.VIEW_CHANGE - a view change event Event.BECOME_SERVER - called after client has joined and is fully working group member Event.CONNECT, Event.DISCONNECT.

Overrides:

down in class Discovery

createRootDir

protected void createRootDir()

handleView

protected void handleView(View view)

remove

protected void remove(String clustername,
          Address addr)

readAll

protected List<PingData> readAll(String clustername)

Reads all information from the given directory under clustername

Returns:

readFile

protected static PingData readFile(File file)

writeToFile

protected void writeToFile(PingData data,
               String clustername)

addressAsString

protected static String addressAsString(Address address)