Package org.jgroups.protocols.pbcast

Class Merger.MergeTask

java.lang.Object

org.jgroups.protocols.pbcast.Merger.MergeTask

All Implemented Interfaces:

java.lang.Runnable

Enclosing class:

Merger

protected class Merger.MergeTask
extends java.lang.Object
implements java.lang.Runnable

Starts the merge protocol (only run by the merge leader). Essentially sends a MERGE_REQ to all coordinators of all subgroups found. Each coord receives its digest and view and returns it. The leader then computes the digest and view for the new group from the return values. Finally, it sends this merged view/digest to all subgroup coordinators; each coordinator will install it in their subgroup.

Field Summary

Fields

Modifier and Type	Field	Description
protected java.util.concurrent.ConcurrentMap<Address,java.util.Collection<Address>>	coords	List of all subpartition coordinators and their members
protected java.util.Set<View>	subviews
protected java.lang.Thread	thread

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MergeTask()

Method Summary

Modifier and Type	Method	Description
protected void	_run(MergeId new_merge_id, java.util.Collection<Address> coordsCopy)	Runs the merge protocol as a leader
protected MutableDigest	consolidateDigests(View new_view, java.util.List<MergeData> merge_rsps)	Merge all digests into one.
protected MergeData	consolidateMergeData(java.util.List<MergeData> merge_rsps, java.util.List<View> subviews)	Merge all MergeData.
protected boolean	getMergeDataFromSubgroupCoordinators(java.util.Map<Address,java.util.Collection<Address>> coords, MergeId new_merge_id, long timeout)	Sends a MERGE_REQ to all coords and populates a list of MergeData (in merge_rsps).
boolean	isRunning()
protected void	removeRejectedMergeRequests(java.util.Collection<Address> coords)	Removed rejected merge requests from merge_rsps and coords.
void	run()
void	start(java.util.Map<Address,View> views)
void	stop()

Methods inherited from class java.lang.Object

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

Field Detail

thread

protected java.lang.Thread thread

coords

protected final java.util.concurrent.ConcurrentMap<Address,java.util.Collection<Address>> coords

List of all subpartition coordinators and their members

subviews

protected final java.util.Set<View> subviews

Constructor Detail

MergeTask

protected MergeTask()

Method Detail

start

public void start(java.util.Map<Address,View> views)

Parameters:

views - Guaranteed to be non-null and to have >= 2 members, or else this thread would not be started

stop

public void stop()

isRunning

public boolean isRunning()

run

public void run()

Specified by:

run in interface java.lang.Runnable

_run

protected void _run(MergeId new_merge_id,
                    java.util.Collection<Address> coordsCopy)
             throws java.lang.Exception

Runs the merge protocol as a leader

Throws:

java.lang.Exception

getMergeDataFromSubgroupCoordinators

protected boolean getMergeDataFromSubgroupCoordinators(java.util.Map<Address,java.util.Collection<Address>> coords,
                                                       MergeId new_merge_id,
                                                       long timeout)

Sends a MERGE_REQ to all coords and populates a list of MergeData (in merge_rsps). Returns after coords.size() response have been received, or timeout msecs have elapsed (whichever is first).

If a subgroup coordinator rejects the MERGE_REQ (e.g. because of participation in a different merge), that member will be removed from coords !

Parameters:

coords - A map of coordinatgor addresses and associated membership lists

new_merge_id - The new merge id

timeout - Max number of msecs to wait for the merge responses from the subgroup coords

removeRejectedMergeRequests

protected void removeRejectedMergeRequests(java.util.Collection<Address> coords)

Removed rejected merge requests from merge_rsps and coords. This method has a lock on merge_rsps

consolidateMergeData

protected MergeData consolidateMergeData(java.util.List<MergeData> merge_rsps,
                                         java.util.List<View> subviews)

Merge all MergeData. All MergeData elements should be disjunct (both views and digests). However, this method is prepared to resolve duplicate entries (for the same member). The resolution strategy for views is to merge only 1 of the duplicate members. Resolution strategy for digests is to take the higher seqnos for duplicate digests.

After merging all members into a Membership and subsequent sorting, the first member of the sorted membership will be the new coordinator. This method has a lock on merge_rsps.

Parameters:

merge_rsps - A list of MergeData items. Elements with merge_rejected=true were removed before. Is guaranteed not to be null and to contain at least 1 member

subviews - Contains a list of Views, each View is a subgroup

consolidateDigests

protected MutableDigest consolidateDigests(View new_view,
                                           java.util.List<MergeData> merge_rsps)

Merge all digests into one. For each sender, the new value is max(highest_delivered), max(highest_received). This method has a lock on merge_rsps