org.jgroups.protocols

Class Discovery

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.Discovery

Direct Known Subclasses:

FILE_PING, JDBC_PING, PING, SHARED_LOOPBACK_PING, TCPGOSSIP, TCPPING

public abstract class Discovery
extends Protocol

The Discovery protocol retrieves the initial membership (used by GMS and MERGE3) by sending discovery requests. We do this in subclasses of Discovery, e.g. by mcasting a discovery request (PING) or, if gossiping is enabled, by contacting the GossipRouter (TCPGOSSIP).

The responses should allow us to determine the coordinator which we have to contact, e.g. in case we want to join the group, or to see if we have diverging views in case of MERGE2.

When we are a server (after having received the BECOME_SERVER event), we'll respond to discovery requests with a discovery response.

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	Discovery.DiscoveryCacheDisseminationTask

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	always_send_physical_addr_with_discovery_request Deprecated.
protected boolean	async_discovery
protected boolean	async_discovery_use_separate_thread_per_request
protected boolean	break_on_coord_rsp
protected java.lang.String	cluster_name
protected Address	current_coord
protected long	discovery_rsp_expiry_time
protected boolean	force_sending_discovery_rsps
protected boolean	is_coord
protected boolean	is_leaving
protected boolean	is_server
protected Address	local_addr
protected int	max_members_in_discovery_request
protected java.util.List<Address>	members
protected int	num_discovery_requests
protected int	num_initial_members Deprecated.
protected int	num_initial_srv_members Deprecated.
protected java.util.Map<java.lang.Long,Responses>	ping_responses
protected boolean	return_entire_cache
protected boolean	send_cache_on_join
protected long	stagger_timeout
protected long	timeout Deprecated.
protected TimeScheduler	timer
protected boolean	transport_supports_multicasting
protected boolean	use_disk_cache
protected View	view
protected static byte[]	WHITESPACE

Fields inherited from class org.jgroups.stack.Protocol

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

Constructor Summary

Constructors

Constructor and Description
Discovery()

Method Summary

Modifier and Type	Method and Description
protected boolean	addDiscoveryResponseToCaches(Address mbr, java.lang.String logical_name, PhysicalAddress physical_addr)
protected void	addResponse(PingData rsp, boolean overwrite)
protected static java.lang.String	addressAsString(Address address)
void	addToCache(java.lang.String filename)
boolean	breakOnCoordResponse()
Discovery	breakOnCoordResponse(boolean flag)
protected static PingData	deserialize(byte[] data)
void	discoveryRequestReceived(Address sender, java.lang.String logical_name, PhysicalAddress physical_addr)
Discovery	discoveryRspExpiryTime(long t)
protected void	disseminateDiscoveryInformation(java.util.List current_mbrs, java.util.List<Address> left_mbrs, java.util.List<Address> new_mbrs) Disseminates cache information (UUID/IP adddress/port/name) to the given members
java.lang.Object	down(Event evt) An event is to be sent down the stack.
void	dumpCache(java.lang.String output_filename)
java.lang.String	findInitialMembersAsString()
Responses	findMembers(java.util.List<Address> members, boolean initial_discovery, boolean async)
protected abstract void	findMembers(java.util.List<Address> members, boolean initial_discovery, Responses responses) Fetches information (e.g.
boolean	forceDiscoveryResponses()
Discovery	forceDiscoveryResponses(boolean f)
java.lang.String	getCurrentCoord()
int	getNumberOfDiscoveryRequestsSent()
int	getNumInitialMembers() Deprecated.
long	getTimeout()
java.lang.String	getView()
ViewId	getViewId()
void	handleConnect()
void	handleDisconnect()
protected void	handleDiscoveryResponse(PingData data, Address sender)
void	init() Called after instance has been created (null constructor) and before protocol is started.
protected boolean	isCoord(Address member)
abstract boolean	isDynamic()
protected boolean	isMergeRunning()
static Buffer	marshal(PingData data)
long	numInitialMembers() Deprecated.
Discovery	numInitialMembers(int num) Deprecated.
java.util.List<java.lang.Integer>	providedUpServices() List of events that are provided to layers above (they will be handled when sent down from above)
protected java.util.List<PingData>	read(java.io.InputStream in)
protected PingData	readPingData(byte[] buffer, int offset, int length)
void	resetStats()
boolean	returnEntireCache()
Discovery	returnEntireCache(boolean flag)
void	sendCacheInformation()
protected void	sendDiscoveryResponse(Address logical_addr, PhysicalAddress physical_addr, java.lang.String logical_name, Address sender, boolean coord)
protected byte[]	serializeWithoutView(PingData data) Creates a byte[] representation of the PingData, but DISCARDING the view it contains.
void	setForceSendingDiscoveryRsps(boolean flag)
void	setNumInitialMembers(int num) Deprecated.
void	setTimeout(long timeout)
long	staggerTimeout()
Discovery	staggerTimeout(long timeout)
void	start() This method is called on a Channel.connect(String).
protected void	startCacheDissemination(java.util.List<Address> curr_mbrs, java.util.List<Address> left_mbrs, java.util.List<Address> new_mbrs)
void	stop() This method is called on a Channel.disconnect().
long	timeout()
Discovery	timeout(long timeout)
java.lang.Object	up(Event evt) An event was received from the layer below.
boolean	useDiskCache()
Discovery	useDiskCache(boolean flag)
void	weedOutCompletedDiscoveryResponses() Removes responses which are done or whose timeout has expired (in the latter case, an expired response is marked as done)
protected void	write(java.util.List<PingData> list, java.io.OutputStream out)

Methods inherited from class org.jgroups.stack.Protocol

accept, afterCreationHook, destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, printStats, providedDownServices, requiredDownServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled, up

Methods inherited from class java.lang.Object

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

Field Detail

timeout

@Deprecated
protected long timeout

Deprecated.

num_initial_members

@Deprecated
protected int num_initial_members

Deprecated.

num_initial_srv_members

@Deprecated
protected int num_initial_srv_members

Deprecated.

break_on_coord_rsp

protected boolean break_on_coord_rsp

return_entire_cache

protected boolean return_entire_cache

stagger_timeout

protected long stagger_timeout

force_sending_discovery_rsps

protected boolean force_sending_discovery_rsps

use_disk_cache

protected boolean use_disk_cache

always_send_physical_addr_with_discovery_request

@Deprecated
protected boolean always_send_physical_addr_with_discovery_request

Deprecated.

max_members_in_discovery_request

protected int max_members_in_discovery_request

discovery_rsp_expiry_time

protected long discovery_rsp_expiry_time

async_discovery

protected boolean async_discovery

async_discovery_use_separate_thread_per_request

protected boolean async_discovery_use_separate_thread_per_request

send_cache_on_join

protected boolean send_cache_on_join

num_discovery_requests

protected int num_discovery_requests

is_server

protected volatile boolean is_server

is_leaving

protected volatile boolean is_leaving

timer

protected TimeScheduler timer

view

protected View view

members

protected final java.util.List<Address> members

is_coord

protected boolean is_coord

local_addr

protected Address local_addr

current_coord

protected Address current_coord

cluster_name

protected java.lang.String cluster_name

ping_responses

protected final java.util.Map<java.lang.Long,Responses> ping_responses

transport_supports_multicasting

protected boolean transport_supports_multicasting

WHITESPACE

protected static final byte[] WHITESPACE

Constructor Detail

Discovery

public Discovery()

Method Detail

setForceSendingDiscoveryRsps

public void setForceSendingDiscoveryRsps(boolean flag)

init

public void init()
          throws java.lang.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 Protocol

Throws:

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

isDynamic

public abstract boolean isDynamic()

handleDisconnect

public void handleDisconnect()

handleConnect

public void handleConnect()

discoveryRequestReceived

public void discoveryRequestReceived(Address sender,
                                     java.lang.String logical_name,
                                     PhysicalAddress physical_addr)

getTimeout

public long getTimeout()

setTimeout

public void setTimeout(long timeout)

getNumInitialMembers

@Deprecated
public int getNumInitialMembers()

Deprecated.

setNumInitialMembers

@Deprecated
public void setNumInitialMembers(int num)

Deprecated.

getNumberOfDiscoveryRequestsSent

public int getNumberOfDiscoveryRequestsSent()

timeout

public long timeout()

timeout

public Discovery timeout(long timeout)

numInitialMembers

@Deprecated
public long numInitialMembers()

Deprecated.

numInitialMembers

@Deprecated
public Discovery numInitialMembers(int num)

Deprecated.

breakOnCoordResponse

public boolean breakOnCoordResponse()

breakOnCoordResponse

public Discovery breakOnCoordResponse(boolean flag)

returnEntireCache

public boolean returnEntireCache()

returnEntireCache

public Discovery returnEntireCache(boolean flag)

staggerTimeout

public long staggerTimeout()

staggerTimeout

public Discovery staggerTimeout(long timeout)

forceDiscoveryResponses

public boolean forceDiscoveryResponses()

forceDiscoveryResponses

public Discovery forceDiscoveryResponses(boolean f)

useDiskCache

public boolean useDiskCache()

useDiskCache

public Discovery useDiskCache(boolean flag)

discoveryRspExpiryTime

public Discovery discoveryRspExpiryTime(long t)

getView

public java.lang.String getView()

getViewId

public ViewId getViewId()

getCurrentCoord

public java.lang.String getCurrentCoord()

isMergeRunning

protected boolean isMergeRunning()

sendCacheInformation

public void sendCacheInformation()

providedUpServices

public java.util.List<java.lang.Integer> providedUpServices()

Description copied from class: Protocol

List of events that are provided to layers above (they will be handled when sent down from above)

Overrides:

providedUpServices in class Protocol

resetStats

public void resetStats()

Overrides:

resetStats in class Protocol

start

public void start()
           throws java.lang.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 Protocol

Throws:

java.lang.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 Protocol

findMembers

protected abstract void findMembers(java.util.List<Address> members,
                                    boolean initial_discovery,
                                    Responses responses)

Fetches information (e.g. physical address, logical name) for the given member addresses. Needs to add responses to the Responses object. If async_discovery is true, this method will be called in a separate thread, otherwise the caller's thread will be used.

Parameters:

members - A list of logical addresses (typically UUIDs). If null, then information for all members is fetched

initial_discovery - Set to true if this is for the initial membership discovery. Some protocols (e.g. file based ones) may return only the information for the coordinator(s).

responses - The list to which responses should be added

findMembers

public Responses findMembers(java.util.List<Address> members,
                             boolean initial_discovery,
                             boolean async)

findInitialMembersAsString

public java.lang.String findInitialMembersAsString()

addToCache

public void addToCache(java.lang.String filename)
                throws java.lang.Exception

Throws:

java.lang.Exception

dumpCache

public void dumpCache(java.lang.String output_filename)
               throws java.lang.Exception

Throws:

java.lang.Exception

up

public java.lang.Object up(Event evt)

Description copied from class: Protocol

An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().

Overrides:

up in class Protocol

handleDiscoveryResponse

protected void handleDiscoveryResponse(PingData data,
                                       Address sender)

down

public java.lang.Object down(Event evt)

Description copied from class: Protocol

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 down_prot.down(). 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().

Overrides:

down in class Protocol

read

protected java.util.List<PingData> read(java.io.InputStream in)

write

protected void write(java.util.List<PingData> list,
                     java.io.OutputStream out)
              throws java.lang.Exception

Throws:

java.lang.Exception

addResponse

protected void addResponse(PingData rsp,
                           boolean overwrite)

weedOutCompletedDiscoveryResponses

public void weedOutCompletedDiscoveryResponses()

Removes responses which are done or whose timeout has expired (in the latter case, an expired response is marked as done)

addDiscoveryResponseToCaches

protected boolean addDiscoveryResponseToCaches(Address mbr,
                                               java.lang.String logical_name,
                                               PhysicalAddress physical_addr)

startCacheDissemination

protected void startCacheDissemination(java.util.List<Address> curr_mbrs,
                                       java.util.List<Address> left_mbrs,
                                       java.util.List<Address> new_mbrs)

serializeWithoutView

protected byte[] serializeWithoutView(PingData data)

Creates a byte[] representation of the PingData, but DISCARDING the view it contains.

Parameters:

data - the PingData instance to serialize.

Returns:

deserialize

protected static PingData deserialize(byte[] data)
                               throws java.lang.Exception

Throws:

java.lang.Exception

marshal

public static Buffer marshal(PingData data)

readPingData

protected PingData readPingData(byte[] buffer,
                                int offset,
                                int length)

sendDiscoveryResponse

protected void sendDiscoveryResponse(Address logical_addr,
                                     PhysicalAddress physical_addr,
                                     java.lang.String logical_name,
                                     Address sender,
                                     boolean coord)

addressAsString

protected static java.lang.String addressAsString(Address address)

isCoord

protected boolean isCoord(Address member)

disseminateDiscoveryInformation

protected void disseminateDiscoveryInformation(java.util.List current_mbrs,
                                               java.util.List<Address> left_mbrs,
                                               java.util.List<Address> new_mbrs)

Disseminates cache information (UUID/IP adddress/port/name) to the given members

Parameters:

current_mbrs - The current members. Guaranteed to be non-null. This is a copy and can be modified.

left_mbrs - The members which left. These are excluded from dissemination. Can be null if no members left

new_mbrs - The new members that we need to disseminate the information to. Will be all members if null.