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Posted to commits@hugegraph.apache.org by GitBox <gi...@apache.org> on 2022/08/16 07:46:08 UTC
[GitHub] [incubator-hugegraph] javeme commented on a diff in pull request #1943: feat(core): cluster role automatic management
javeme commented on code in PR #1943:
URL: https://github.com/apache/incubator-hugegraph/pull/1943#discussion_r946424038
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
Review Comment:
mark final
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
+
+ Integer epoch;
+
+ public UnKnownState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ MetaDataAdapter adapter = context.adapter();
+ Optional<MetaData> metaDataOpt = adapter.query();
+ if (!metaDataOpt.isPresent()) {
+ context.reset();
+ this.epoch = this.epoch == null ? 1 : this.epoch + 1;
+ context.epoch(this.epoch);
+ return new CandidateState(this.epoch);
+ }
+
+ MetaData metaData = metaDataOpt.get();
+ context.epoch(metaData.epoch());
+ if (metaData.isMaster(context.node())) {
+ return new MasterState(metaData);
+ } else {
+ return new WorkerState(metaData);
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::unknown;
+ }
+ }
+
+ private static class SafeState implements RoleState {
+
+ Integer epoch;
+
+ public SafeState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ RoleState.heartBeatPark(context);
+ return new UnKnownState(this.epoch).transform(context);
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::safe;
+ }
+ }
+
+ private static class MasterState implements RoleState {
+
+ MetaData metaData;
Review Comment:
ditto
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaData.java:
##########
@@ -0,0 +1,45 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Objects;
+
+public class MetaData {
+
+ String node;
+ long count;
+ int epoch;
+
+ public MetaData(String node, int epoch) {
+ this.node = node;
+ this.epoch = epoch;
+ this.count = 1;
+ }
+
+ public void increaseCount() {
+ this.count++;
+ }
+
+ public boolean isMaster(String node) {
+ return Objects.equals(this.node, node);
+ }
+
+ public int epoch() {
+ return this.epoch;
+ }
+
+ public long count() {
+ return this.count;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof MetaData)) return false;
Review Comment:
ditto
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
+
+ Integer epoch;
+
+ public UnKnownState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ MetaDataAdapter adapter = context.adapter();
+ Optional<MetaData> metaDataOpt = adapter.query();
+ if (!metaDataOpt.isPresent()) {
+ context.reset();
+ this.epoch = this.epoch == null ? 1 : this.epoch + 1;
+ context.epoch(this.epoch);
+ return new CandidateState(this.epoch);
+ }
+
+ MetaData metaData = metaDataOpt.get();
+ context.epoch(metaData.epoch());
+ if (metaData.isMaster(context.node())) {
+ return new MasterState(metaData);
+ } else {
+ return new WorkerState(metaData);
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::unknown;
+ }
+ }
+
+ private static class SafeState implements RoleState {
+
+ Integer epoch;
+
+ public SafeState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ RoleState.heartBeatPark(context);
+ return new UnKnownState(this.epoch).transform(context);
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::safe;
+ }
+ }
+
+ private static class MasterState implements RoleState {
+
+ MetaData metaData;
+
+ public MasterState(MetaData metaData) {
+ this.metaData = metaData;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ this.metaData.increaseCount();
+ RoleState.heartBeatPark(context);
+ if (context.adapter().postDelyIfPresent(this.metaData, -1)) {
+ return this;
+ }
+ context.reset();
+ context.epoch(this.metaData.epoch());
+ return new UnKnownState(this.metaData.epoch());
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::master;
+ }
+ }
+
+ private static class WorkerState implements RoleState {
+
+ private MetaData metaData;
+ private int count = 0;
+
+ public WorkerState(MetaData metaData) {
+ this.metaData = metaData;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ RoleState.heartBeatPark(context);
+ RoleState nextState = new UnKnownState(this.metaData.epoch()).transform(context);
+ if (nextState instanceof WorkerState) {
+ this.merge((WorkerState) nextState);
+ if (this.count > context.config().exceedsWorkerCount()) {
+ return new CandidateState(this.metaData.epoch() + 1);
+ } else {
+ return this;
+ }
+ } else {
+ return nextState;
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::worker;
+ }
+
+ public void merge(WorkerState state) {
+ if (state.metaData.epoch() > this.metaData.epoch()) {
+ this.count = 0;
+ this.metaData = state.metaData;
+ } else if (state.metaData.epoch() < this.metaData.epoch()){
+ throw new IllegalStateException("Epoch must increase");
+ } else if (state.metaData.epoch() == this.metaData.epoch() &&
+ state.metaData.count() < this.metaData.count()) {
+ throw new IllegalStateException("Meta count must increase");
+ } else if (state.metaData.epoch() == this.metaData.epoch() &&
+ state.metaData.count() > this.metaData.count()) {
+ this.count = 0;
+ this.metaData = state.metaData;
+ } else {
+ this.count++;
+ }
+ }
+ }
+
+ private static class CandidateState implements RoleState {
+
+ Integer epoch;
Review Comment:
ditto
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachine.java:
##########
@@ -0,0 +1,9 @@
+package com.baidu.hugegraph.election;
+
+public interface RoleElectionStateMachine {
+
+ void shutdown();
+
+ void apply(StateMachineCallback stateMachineCallback);
+
Review Comment:
delete the empty line
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaData.java:
##########
@@ -0,0 +1,45 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Objects;
+
+public class MetaData {
+
+ String node;
+ long count;
+ int epoch;
+
+ public MetaData(String node, int epoch) {
+ this.node = node;
+ this.epoch = epoch;
+ this.count = 1;
+ }
+
+ public void increaseCount() {
+ this.count++;
+ }
+
+ public boolean isMaster(String node) {
+ return Objects.equals(this.node, node);
+ }
+
+ public int epoch() {
+ return this.epoch;
+ }
+
+ public long count() {
+ return this.count;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
Review Comment:
expect to wrap line after if statement
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
Review Comment:
UnKnown => Unknown
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
+
+ Integer epoch;
+
+ public UnKnownState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ MetaDataAdapter adapter = context.adapter();
+ Optional<MetaData> metaDataOpt = adapter.query();
+ if (!metaDataOpt.isPresent()) {
+ context.reset();
+ this.epoch = this.epoch == null ? 1 : this.epoch + 1;
+ context.epoch(this.epoch);
+ return new CandidateState(this.epoch);
+ }
+
+ MetaData metaData = metaDataOpt.get();
+ context.epoch(metaData.epoch());
+ if (metaData.isMaster(context.node())) {
+ return new MasterState(metaData);
+ } else {
+ return new WorkerState(metaData);
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::unknown;
+ }
+ }
+
+ private static class SafeState implements RoleState {
+
+ Integer epoch;
Review Comment:
mark private
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaDataAdapter.java:
##########
@@ -0,0 +1,12 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+
+public interface MetaDataAdapter {
+
+ boolean postDelyIfPresent(MetaData metaData, long delySecond);
Review Comment:
Dely => Delay?
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaDataAdapter.java:
##########
@@ -0,0 +1,12 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+
+public interface MetaDataAdapter {
+
+ boolean postDelyIfPresent(MetaData metaData, long delySecond);
+
+ Optional<MetaData> queryDelay(long delySecond);
Review Comment:
delySecond => delaySecond
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
+
+ Integer epoch;
Review Comment:
ditto
##########
hugegraph-test/src/main/java/com/baidu/hugegraph/core/RoleElectionStateMachineTest.java:
##########
@@ -0,0 +1,237 @@
+package com.baidu.hugegraph.core;
+
+import java.net.SocketTimeoutException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.election.Config;
+import com.baidu.hugegraph.election.MetaData;
+import com.baidu.hugegraph.election.MetaDataAdapter;
+import com.baidu.hugegraph.election.RoleElectionStateMachine;
+import com.baidu.hugegraph.election.RoleElectionStateMachineImpl;
+import com.baidu.hugegraph.election.StateMachineCallback;
+import com.baidu.hugegraph.election.StateMachineContext;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RoleElectionStateMachineTest {
+
+ public static class LogEntry {
+
+ Integer epoch;
+ String node;
+
+ Role role;
+
+ enum Role {
+ master,
+ worker,
+ candidate,
+ safe,
+ unknown
+ }
+
+ public LogEntry(Integer epoch, String node, Role role) {
+ this.epoch = epoch;
+ this.node = node;
+ this.role = role;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof LogEntry)) return false;
+ LogEntry logEntry = (LogEntry) o;
+ return Objects.equals(epoch, logEntry.epoch) && Objects.equals(node, logEntry.node) && role == logEntry.role;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(epoch, node, role);
+ }
+
+ @Override
+ public String toString() {
+ return "LogEntry{" +
+ "epoch=" + epoch +
+ ", node='" + node + '\'' +
+ ", role=" + role +
+ '}';
+ }
+ }
+
+ private static class TestConfig implements Config {
+
+ String node;
+
+ public TestConfig(String node) {
+ this.node = node;
+ }
+
+ @Override
+ public String node() {
+ return this.node;
+ }
+
+ @Override
+ public int exceedsFailCount() {
+ return 10;
+ }
+
+ @Override
+ public long randomTimeoutMillisecond() {
+ return 400;
+ }
+
+ @Override
+ public long heartBeatIntervalSecond() {
+ return 1;
+ }
+
+ @Override
+ public int exceedsWorkerCount() {
+ return 5;
+ }
+ }
+
+ @Test
+ public void testStateMachine() throws InterruptedException {
+ final CountDownLatch stop = new CountDownLatch(3);
+ final int MAX_COUNT = 100;
+ final List<LogEntry> logRecords = Collections.synchronizedList(new ArrayList<>(MAX_COUNT));
+ final StateMachineCallback callback = new StateMachineCallback() {
+
+ @Override
+ public void master(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.master));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void worker(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.worker));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void candidate(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.candidate));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void unknown(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.unknown));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void safe(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.safe));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void error(StateMachineContext context, Throwable e) {
+
+ }
+ };
+ final MetaDataAdapter adapter = new MetaDataAdapter() {
+ int epoch = 0;
+ int count = 0;
+ Map<Integer, MetaData> data = new ConcurrentHashMap<>();
+ @Override
Review Comment:
add a blank line
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaDataAdapter.java:
##########
@@ -0,0 +1,12 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+
+public interface MetaDataAdapter {
+
+ boolean postDelyIfPresent(MetaData metaData, long delySecond);
+
+ Optional<MetaData> queryDelay(long delySecond);
Review Comment:
prefer queryWithDelay name
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaData.java:
##########
@@ -0,0 +1,45 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Objects;
+
+public class MetaData {
+
+ String node;
+ long count;
+ int epoch;
Review Comment:
mark private
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/Config.java:
##########
@@ -0,0 +1,14 @@
+package com.baidu.hugegraph.election;
Review Comment:
add license header
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaData.java:
##########
@@ -0,0 +1,45 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Objects;
+
+public class MetaData {
Review Comment:
can we rename to RoleStateData?
##########
hugegraph-test/src/main/java/com/baidu/hugegraph/core/RoleElectionStateMachineTest.java:
##########
@@ -0,0 +1,237 @@
+package com.baidu.hugegraph.core;
+
+import java.net.SocketTimeoutException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.election.Config;
+import com.baidu.hugegraph.election.MetaData;
+import com.baidu.hugegraph.election.MetaDataAdapter;
+import com.baidu.hugegraph.election.RoleElectionStateMachine;
+import com.baidu.hugegraph.election.RoleElectionStateMachineImpl;
+import com.baidu.hugegraph.election.StateMachineCallback;
+import com.baidu.hugegraph.election.StateMachineContext;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RoleElectionStateMachineTest {
+
+ public static class LogEntry {
+
+ Integer epoch;
+ String node;
+
+ Role role;
+
+ enum Role {
+ master,
+ worker,
+ candidate,
+ safe,
+ unknown
+ }
+
+ public LogEntry(Integer epoch, String node, Role role) {
+ this.epoch = epoch;
+ this.node = node;
+ this.role = role;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (!(o instanceof LogEntry)) return false;
+ LogEntry logEntry = (LogEntry) o;
+ return Objects.equals(epoch, logEntry.epoch) && Objects.equals(node, logEntry.node) && role == logEntry.role;
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(epoch, node, role);
+ }
+
+ @Override
+ public String toString() {
+ return "LogEntry{" +
+ "epoch=" + epoch +
+ ", node='" + node + '\'' +
+ ", role=" + role +
+ '}';
+ }
+ }
+
+ private static class TestConfig implements Config {
+
+ String node;
+
+ public TestConfig(String node) {
+ this.node = node;
+ }
+
+ @Override
+ public String node() {
+ return this.node;
+ }
+
+ @Override
+ public int exceedsFailCount() {
+ return 10;
+ }
+
+ @Override
+ public long randomTimeoutMillisecond() {
+ return 400;
+ }
+
+ @Override
+ public long heartBeatIntervalSecond() {
+ return 1;
+ }
+
+ @Override
+ public int exceedsWorkerCount() {
+ return 5;
+ }
+ }
+
+ @Test
+ public void testStateMachine() throws InterruptedException {
+ final CountDownLatch stop = new CountDownLatch(3);
+ final int MAX_COUNT = 100;
+ final List<LogEntry> logRecords = Collections.synchronizedList(new ArrayList<>(MAX_COUNT));
+ final StateMachineCallback callback = new StateMachineCallback() {
+
+ @Override
+ public void master(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.master));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void worker(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.worker));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void candidate(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.candidate));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void unknown(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.unknown));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void safe(StateMachineContext context) {
+ Integer epochId = context.epoch();
+ String node = context.node();
+ logRecords.add(new LogEntry(epochId, node, LogEntry.Role.safe));
+ if (logRecords.size() > MAX_COUNT) {
+ context.stateMachine().shutdown();
+ }
+ }
+
+ @Override
+ public void error(StateMachineContext context, Throwable e) {
+
+ }
+ };
Review Comment:
add a blank line
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/RoleElectionStateMachineImpl.java:
##########
@@ -0,0 +1,281 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+import java.util.concurrent.locks.LockSupport;
+
+import com.baidu.hugegraph.util.E;
+
+public class RoleElectionStateMachineImpl implements RoleElectionStateMachine {
+
+ private volatile boolean shutdown = false;
+ private Config config;
+
+ private volatile RoleState state;
+
+ private final MetaDataAdapter metaDataAdapter;
+
+ public RoleElectionStateMachineImpl(Config config, MetaDataAdapter adapter) {
+ this.config = config;
+ this.metaDataAdapter = adapter;
+ this.state = new UnKnownState(null);
+ }
+
+ @Override
+ public void shutdown() {
+ this.shutdown = true;
+ }
+
+ @Override
+ public void apply(StateMachineCallback stateMachineCallback) {
+ int failCount = 0;
+ StateMachineContextImpl context = new StateMachineContextImpl(this);
+ while (!this.shutdown) {
+ E.checkArgumentNotNull(this.state, "State don't be null");
+ try {
+ this.state = state.transform(context);
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ failCount = 0;
+ } catch (Throwable e) {
+ stateMachineCallback.error(context, e);
+ failCount ++;
+ if (failCount >= this.config.exceedsFailCount()) {
+ this.state = new SafeState(context.epoch());
+ Callback runnable = this.state.callback(stateMachineCallback);
+ runnable.call(context);
+ }
+ }
+ }
+ }
+
+ private interface RoleState {
+
+ RoleState transform(StateMachineContext context);
+
+ Callback callback(StateMachineCallback callback);
+
+ static void heartBeatPark(StateMachineContext context) {
+ long heartBeatIntervalSecond = context.config().heartBeatIntervalSecond();
+ LockSupport.parkNanos(heartBeatIntervalSecond * 1_000_000_000);
+ }
+
+ static void randomPark(StateMachineContext context) {
+ long randomTimeout = context.config().randomTimeoutMillisecond();
+ LockSupport.parkNanos(randomTimeout * 1_000_000);
+ }
+ }
+
+ @FunctionalInterface
+ private interface Callback {
+
+ void call(StateMachineContext context);
+ }
+
+ private static class UnKnownState implements RoleState {
+
+ Integer epoch;
+
+ public UnKnownState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ MetaDataAdapter adapter = context.adapter();
+ Optional<MetaData> metaDataOpt = adapter.query();
+ if (!metaDataOpt.isPresent()) {
+ context.reset();
+ this.epoch = this.epoch == null ? 1 : this.epoch + 1;
+ context.epoch(this.epoch);
+ return new CandidateState(this.epoch);
+ }
+
+ MetaData metaData = metaDataOpt.get();
+ context.epoch(metaData.epoch());
+ if (metaData.isMaster(context.node())) {
+ return new MasterState(metaData);
+ } else {
+ return new WorkerState(metaData);
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::unknown;
+ }
+ }
+
+ private static class SafeState implements RoleState {
+
+ Integer epoch;
+
+ public SafeState(Integer epoch) {
+ this.epoch = epoch;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ RoleState.heartBeatPark(context);
+ return new UnKnownState(this.epoch).transform(context);
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::safe;
+ }
+ }
+
+ private static class MasterState implements RoleState {
+
+ MetaData metaData;
+
+ public MasterState(MetaData metaData) {
+ this.metaData = metaData;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ this.metaData.increaseCount();
+ RoleState.heartBeatPark(context);
+ if (context.adapter().postDelyIfPresent(this.metaData, -1)) {
+ return this;
+ }
+ context.reset();
+ context.epoch(this.metaData.epoch());
+ return new UnKnownState(this.metaData.epoch());
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::master;
+ }
+ }
+
+ private static class WorkerState implements RoleState {
+
+ private MetaData metaData;
+ private int count = 0;
+
+ public WorkerState(MetaData metaData) {
+ this.metaData = metaData;
+ }
+
+ @Override
+ public RoleState transform(StateMachineContext context) {
+ RoleState.heartBeatPark(context);
+ RoleState nextState = new UnKnownState(this.metaData.epoch()).transform(context);
+ if (nextState instanceof WorkerState) {
+ this.merge((WorkerState) nextState);
+ if (this.count > context.config().exceedsWorkerCount()) {
+ return new CandidateState(this.metaData.epoch() + 1);
+ } else {
+ return this;
+ }
+ } else {
+ return nextState;
+ }
+ }
+
+ @Override
+ public Callback callback(StateMachineCallback callback) {
+ return callback::worker;
+ }
+
+ public void merge(WorkerState state) {
+ if (state.metaData.epoch() > this.metaData.epoch()) {
+ this.count = 0;
+ this.metaData = state.metaData;
+ } else if (state.metaData.epoch() < this.metaData.epoch()){
+ throw new IllegalStateException("Epoch must increase");
+ } else if (state.metaData.epoch() == this.metaData.epoch() &&
+ state.metaData.count() < this.metaData.count()) {
Review Comment:
align with `state.metaData.epoch()`
##########
hugegraph-core/src/main/java/com/baidu/hugegraph/election/MetaDataAdapter.java:
##########
@@ -0,0 +1,12 @@
+package com.baidu.hugegraph.election;
+
+import java.util.Optional;
+
+public interface MetaDataAdapter {
+
+ boolean postDelyIfPresent(MetaData metaData, long delySecond);
Review Comment:
prefer delayIfNodePresent
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