org.jgroups.blocks

Class MultiRequest

java.lang.Object

org.jgroups.blocks.Request

org.jgroups.blocks.MultiRequest

All Implemented Interfaces:

java.util.concurrent.Future, RspCollector, Command, NotifyingFuture

public class MultiRequest
extends Request

Sends a request to multiple destinations. Alternative implementation when we have few targets: between UnicastRequest with 1 target and GroupRequest with many destination members. Performance is about the same as for GroupRequest, but this class should use less memory as it doesn't create hashmaps. Don't use with many targets as we have to do a linear search through an array of targets to match a response to a request.

MultiRequest is currently not used

Since:

2.9

Author:

Bela Ban

Field Summary

Fields

Modifier and Type	Field and Description
protected int	expected_mbrs

Fields inherited from class org.jgroups.blocks.Request

block_for_results, completed, corr, done, GET_ABS_MAJORITY, GET_ALL, GET_FIRST, GET_MAJORITY, GET_N, GET_NONE, listener, lock, log, options, req_id, REQUEST_ID, request_msg, transport

Constructor Summary

Constructors

Constructor and Description
MultiRequest(Message m, RequestCorrelator corr, Address target, RequestOptions options, int expected_mbrs)
MultiRequest(Message m, RequestCorrelator corr, java.util.Collection<Address> mbrs, RequestOptions options, int expected_mbrs)
MultiRequest(Message m, Transport transport, java.util.Collection<Address> mbrs, RequestOptions options, int expected_mbrs)

Method Summary

Modifier and Type	Method and Description
RspList	get()
RspList	get(long timeout, java.util.concurrent.TimeUnit unit)
boolean	getAnycasting()
RspList	getResults() Returns the results as a RspList
void	receiveResponse(java.lang.Object response_value, Address sender) Callback (called by RequestCorrelator or Transport).
protected boolean	responsesComplete()
void	sendRequest()
void	setAnycasting(boolean anycasting)
void	suspect(Address suspected_member) Callback (called by RequestCorrelator or Transport).
java.lang.String	toString()
void	viewChange(View new_view) Any member of 'membership' that is not in the new view is flagged as SUSPECTED.

Methods inherited from class org.jgroups.blocks.Request

cancel, checkCompletion, execute, getBlockForResults, getRequestId, getResponsesComplete, isCancelled, isDone, modeToString, responsesComplete, setBlockForResults, setListener, setResponseFilter, waitForResults

Methods inherited from class java.lang.Object

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

Field Detail

expected_mbrs

protected final int expected_mbrs

Constructor Detail

MultiRequest

public MultiRequest(Message m,
                    RequestCorrelator corr,
                    java.util.Collection<Address> mbrs,
                    RequestOptions options,
                    int expected_mbrs)

Parameters:

m - The message to be sent

corr - The request correlator to be used. A request correlator sends requests tagged with a unique ID and notifies the sender when matching responses are received. The reason GroupRequest uses it instead of a Transport is that multiple requests/responses might be sent/received concurrently.

mbrs - The initial membership. This value reflects the membership to which the request is sent (and from which potential responses are expected). Is reset by reset().

options - The options to be passed to the request

MultiRequest

public MultiRequest(Message m,
                    RequestCorrelator corr,
                    Address target,
                    RequestOptions options,
                    int expected_mbrs)

MultiRequest

public MultiRequest(Message m,
                    Transport transport,
                    java.util.Collection<Address> mbrs,
                    RequestOptions options,
                    int expected_mbrs)

Parameters:

timeout - Time to wait for responses (ms). A value of <= 0 means wait indefinitely (e.g. if a suspicion service is available; timeouts are not needed).

Method Detail

getAnycasting

public boolean getAnycasting()

setAnycasting

public void setAnycasting(boolean anycasting)

sendRequest

public void sendRequest()
                 throws java.lang.Exception

Specified by:

sendRequest in class Request

Throws:

java.lang.Exception

receiveResponse

public void receiveResponse(java.lang.Object response_value,
                            Address sender)

Callback (called by RequestCorrelator or Transport). Adds a response to the response table. When all responses have been received, execute() returns.

Specified by:

receiveResponse in interface RspCollector

Specified by:

receiveResponse in class Request

suspect

public void suspect(Address suspected_member)

Callback (called by RequestCorrelator or Transport). Report to GroupRequest that a member is reported as faulty (suspected). This method would probably be called when getting a suspect message from a failure detector (where available). It is used to exclude faulty members from the response list.

Specified by:

suspect in interface RspCollector

Specified by:

suspect in class Request

viewChange

public void viewChange(View new_view)

Any member of 'membership' that is not in the new view is flagged as SUSPECTED. Any member in the new view that is not in the membership (ie, the set of responses expected for the current RPC) will not be added to it. If we did this we might run into the following problem:

• Membership is {A,B}
• A sends a synchronous group RPC (which sleeps for 60 secs in the invocation handler)
• C joins while A waits for responses from A and B
• If this would generate a new view {A,B,C} and if this expanded the response set to {A,B,C}, A would wait forever on C's response because C never received the request in the first place, therefore won't send a response.

Specified by:

viewChange in interface RspCollector

Specified by:

viewChange in class Request

getResults

public RspList getResults()

Returns the results as a RspList

get

public RspList get()
            throws java.lang.InterruptedException,
                   java.util.concurrent.ExecutionException

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

get

public RspList get(long timeout,
                   java.util.concurrent.TimeUnit unit)
            throws java.lang.InterruptedException,
                   java.util.concurrent.ExecutionException,
                   java.util.concurrent.TimeoutException

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

java.util.concurrent.TimeoutException

toString

public java.lang.String toString()

Overrides:

toString in class Request

responsesComplete

protected boolean responsesComplete()

Specified by:

responsesComplete in class Request