/*
* Copyright (c) 2008-2013, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.replicatedmap.impl.record;
import com.hazelcast.core.Member;
import com.hazelcast.instance.MemberImpl;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;
import com.hazelcast.replicatedmap.impl.operation.ReplicatedMapDataSerializerHook;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
/**
* A vector clock implementation based on hashcodes of the Hazelcast members UUID to solve conflicts on
* replication updates
*/
public final class VectorClockTimestamp
implements IdentifiedDataSerializable {
private Map<Member, Integer> clocks;
public VectorClockTimestamp() {
this.clocks = Collections.emptyMap();
}
private VectorClockTimestamp(Map<Member, Integer> clocks) {
this.clocks = Collections.unmodifiableMap(clocks);
}
VectorClockTimestamp incrementClock0(Member localMember) {
Map<Member, Integer> copy = new HashMap<Member, Integer>(clocks);
Integer clock = copy.get(localMember);
if (clock == null) {
clock = 0;
}
copy.put(localMember, ++clock);
return new VectorClockTimestamp(copy);
}
VectorClockTimestamp applyVector0(VectorClockTimestamp update) {
Map<Member, Integer> copy = new HashMap<Member, Integer>(clocks);
for (Member m : update.clocks.keySet()) {
final Integer currentClock = copy.get(m);
final Integer updateClock = update.clocks.get(m);
if (smaller(currentClock, updateClock)) {
copy.put(m, updateClock);
}
}
return new VectorClockTimestamp(copy);
}
@Override
public void writeData(ObjectDataOutput dataOutput)
throws IOException {
Map<Member, Integer> clocks = this.clocks;
dataOutput.writeInt(clocks.size());
for (Entry<Member, Integer> entry : clocks.entrySet()) {
entry.getKey().writeData(dataOutput);
dataOutput.writeInt(entry.getValue());
}
}
@Override
public void readData(ObjectDataInput dataInput)
throws IOException {
int size = dataInput.readInt();
Map<Member, Integer> data = new HashMap<Member, Integer>();
for (int i = 0; i < size; i++) {
Member m = new MemberImpl();
m.readData(dataInput);
int clock = dataInput.readInt();
data.put(m, clock);
}
this.clocks = Collections.unmodifiableMap(data);
}
@Override
public int getId() {
return ReplicatedMapDataSerializerHook.VECTOR;
}
@Override
public int getFactoryId() {
return ReplicatedMapDataSerializerHook.F_ID;
}
@Override
public String toString() {
return "Vector{" + "clocks=" + clocks + '}';
}
private boolean smaller(Integer int1, Integer int2) {
int i1 = int1 == null ? 0 : int1;
int i2 = int2 == null ? 0 : int2;
return i1 < i2;
}
static VectorClockTimestamp copyVector(VectorClockTimestamp vectorClockTimestamp) {
Map<Member, Integer> clocks = new HashMap<Member, Integer>();
for (Entry<Member, Integer> entry : vectorClockTimestamp.clocks.entrySet()) {
MemberImpl member = new MemberImpl((MemberImpl) entry.getKey());
Integer value = entry.getValue();
clocks.put(member, value);
}
return new VectorClockTimestamp(clocks);
}
static boolean happenedBefore(VectorClockTimestamp x, VectorClockTimestamp y) {
Set<Member> members = new HashSet<Member>(x.clocks.keySet());
members.addAll(y.clocks.keySet());
boolean hasLesser = false;
for (Member m : members) {
int xi = x.clocks.get(m) != null ? x.clocks.get(m) : 0;
int yi = y.clocks.get(m) != null ? y.clocks.get(m) : 0;
if (xi > yi) {
return false;
}
if (xi < yi) {
hasLesser = true;
}
}
return hasLesser;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
VectorClockTimestamp that = (VectorClockTimestamp) o;
if (clocks != null ? !clocks.equals(that.clocks) : that.clocks != null) {
return false;
}
return true;
}
@Override
public int hashCode() {
return clocks != null ? clocks.hashCode() : 0;
}
}