An alternative coordinator that makes local decisions based on membership service

DinkyCoordinator.java (text/x-java), 2.18 KB, created by Robert Newson on 2008-06-26 10:16:13 UTC

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Description: An alternative coordinator that makes local decisions based on membership service

Filename:

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Creator: Robert Newson

Created: 2008-06-26 10:16:13 UTC

Size: 2.18 KB

patch

obsolete

>package com.ironmountain.bedrock.groups.impl; > >import static java.util.concurrent.TimeUnit.MILLISECONDS; > >import java.util.Arrays; >import java.util.concurrent.atomic.AtomicBoolean; > >import org.apache.catalina.tribes.ChannelException; >import org.apache.catalina.tribes.Member; >import org.apache.catalina.tribes.group.AbsoluteOrder; >import org.apache.catalina.tribes.group.ChannelInterceptorBase; > >/** > * A dinky coordinator, just uses a sorted version of the member array. > * > * @author rnewson > * > */ >public class DinkyCoordinator extends ChannelInterceptorBase { > > private Member[] view; > > private AtomicBoolean membershipChanged = new AtomicBoolean(); > > private void membershipChanged() { > membershipChanged.set(true); > } > > @Override > public void memberAdded(final Member member) { > super.memberAdded(member); > membershipChanged(); > installViewWhenStable(); > } > > @Override > public void memberDisappeared(final Member member) { > super.memberDisappeared(member); > membershipChanged(); > installViewWhenStable(); > } > > /** > * Override to receive view changes. > * > * @param view > */ > protected void viewChange(final Member[] view) { > } > > @Override > public void start(int svc) throws ChannelException { > super.start(svc); > installViewWhenStable(); > } > > private void installViewWhenStable() { > int stableCount = 0; > > while (stableCount < 10) { > if (membershipChanged.compareAndSet(true, false)) { > stableCount = 0; > } else { > stableCount++; > } > try { > MILLISECONDS.sleep(250); > } catch (final InterruptedException e) { > Thread.currentThread().interrupt(); > } > } > > final Member[] members = getMembers(); > final Member[] view = Arrays.copyOf(members, members.length + 1); > view[members.length] = getLocalMember(false); > Arrays.sort(view, AbsoluteOrder.comp); > if (Arrays.equals(view, this.view)) { > return; > } > this.view = view; > viewChange(view); > } > > @Override > public void stop(int svc) throws ChannelException { > super.stop(svc); > } > > public Member[] getView() { > return view; > } > > public Member getCoordinator() { > return view == null ? null : view[0]; > } > > public boolean isCoordinator() { > return view == null ? false : getLocalMember(false).equals( > getCoordinator()); > } > >} View Attachment As Raw

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