Merge pull request #8125 from eugenp/revert-8119-BAEL-3275-2

Revert "BAEL-3275: Using blocking queue for pub-sub"

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/applicationreview/ApplicationReviewEvents.java

@@ -0,0 +1,5 @@
+package com.baeldung.spring.statemachine.applicationreview;
+
+public enum ApplicationReviewEvents {
+    APPROVE, REJECT
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/applicationreview/ApplicationReviewStates.java

@@ -0,0 +1,5 @@
+package com.baeldung.spring.statemachine.applicationreview;
+
+public enum ApplicationReviewStates {
+    PEER_REVIEW, PRINCIPAL_REVIEW, APPROVED, REJECTED
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/ForkJoinStateMachineConfiguration.java

@@ -0,0 +1,74 @@
+package com.baeldung.spring.statemachine.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.statemachine.config.EnableStateMachine;
+import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
+import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
+import org.springframework.statemachine.guard.Guard;
+
+@Configuration
+@EnableStateMachine
+public class ForkJoinStateMachineConfiguration extends StateMachineConfigurerAdapter<String, String> {
+
+    @Override
+    public void configure(StateMachineConfigurationConfigurer<String, String> config)
+            throws Exception {
+        config
+                .withConfiguration()
+                .autoStartup(true)
+                .listener(new StateMachineListener());
+    }
+
+    @Override
+    public void configure(StateMachineStateConfigurer<String, String> states) throws Exception {
+        states
+                .withStates()
+                .initial("SI")
+                .fork("SFork")
+                .join("SJoin")
+                .end("SF")
+                .and()
+                .withStates()
+                    .parent("SFork")
+                    .initial("Sub1-1")
+                    .end("Sub1-2")
+                .and()
+                .withStates()
+                    .parent("SFork")
+                    .initial("Sub2-1")
+                    .end("Sub2-2");
+    }
+
+    @Override
+    public void configure(StateMachineTransitionConfigurer<String, String> transitions) throws Exception {
+        transitions.withExternal()
+                .source("SI").target("SFork").event("E1")
+                .and().withExternal()
+                    .source("Sub1-1").target("Sub1-2").event("sub1")
+                .and().withExternal()
+                    .source("Sub2-1").target("Sub2-2").event("sub2")
+                .and()
+                .withFork()
+                    .source("SFork")
+                    .target("Sub1-1")
+                    .target("Sub2-1")
+                .and()
+                .withJoin()
+                    .source("Sub1-2")
+                    .source("Sub2-2")
+                    .target("SJoin");
+    }
+
+    @Bean
+    public Guard<String, String> mediumGuard() {
+        return ctx -> false;
+    }
+
+    @Bean
+    public Guard<String, String> highGuard() {
+        return ctx -> false;
+    }
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/HierarchicalStateMachineConfiguration.java

@@ -0,0 +1,47 @@
+package com.baeldung.spring.statemachine.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.statemachine.config.EnableStateMachine;
+import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
+import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
+
+@Configuration
+@EnableStateMachine
+public class HierarchicalStateMachineConfiguration extends StateMachineConfigurerAdapter<String, String> {
+
+    @Override
+    public void configure(StateMachineConfigurationConfigurer<String, String> config)
+            throws Exception {
+        config
+                .withConfiguration()
+                .autoStartup(true)
+                .listener(new StateMachineListener());
+    }
+
+    @Override
+    public void configure(StateMachineStateConfigurer<String, String> states) throws Exception {
+        states
+                .withStates()
+                .initial("SI")
+                .state("SI")
+                .end("SF")
+                .and()
+                .withStates()
+                    .parent("SI")
+                    .initial("SUB1")
+                    .state("SUB2")
+                    .end("SUBEND");
+    }
+
+    @Override
+    public void configure(StateMachineTransitionConfigurer<String, String> transitions) throws Exception {
+        transitions.withExternal()
+                .source("SI").target("SF").event("end")
+                .and().withExternal()
+                .source("SUB1").target("SUB2").event("se1")
+                .and().withExternal()
+                .source("SUB2").target("SUBEND").event("s-end");
+    }
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/JunctionStateMachineConfiguration.java

@@ -0,0 +1,60 @@
+package com.baeldung.spring.statemachine.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.statemachine.config.EnableStateMachine;
+import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
+import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
+import org.springframework.statemachine.guard.Guard;
+
+@Configuration
+@EnableStateMachine
+public class JunctionStateMachineConfiguration extends StateMachineConfigurerAdapter<String, String> {
+
+    @Override
+    public void configure(StateMachineConfigurationConfigurer<String, String> config)
+            throws Exception {
+        config
+                .withConfiguration()
+                .autoStartup(true)
+                .listener(new StateMachineListener());
+    }
+
+    @Override
+    public void configure(StateMachineStateConfigurer<String, String> states) throws Exception {
+        states
+                .withStates()
+                .initial("SI")
+                .junction("SJ")
+                .state("high")
+                .state("medium")
+                .state("low")
+                .end("SF");
+    }
+
+    @Override
+    public void configure(StateMachineTransitionConfigurer<String, String> transitions) throws Exception {
+        transitions.withExternal()
+                .source("SI").target("SJ").event("E1")
+                .and()
+                .withJunction()
+                .source("SJ")
+                .first("high", highGuard())
+                .then("medium", mediumGuard())
+                .last("low")
+                .and().withExternal()
+                .source("low").target("SF").event("end");
+    }
+
+    @Bean
+    public Guard<String, String> mediumGuard() {
+        return ctx -> false;
+    }
+
+    @Bean
+    public Guard<String, String> highGuard() {
+        return ctx -> false;
+    }
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/SimpleEnumStateMachineConfiguration.java

@@ -0,0 +1,47 @@
+package com.baeldung.spring.statemachine.config;
+
+import com.baeldung.spring.statemachine.applicationreview.ApplicationReviewEvents;
+import com.baeldung.spring.statemachine.applicationreview.ApplicationReviewStates;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.statemachine.config.EnableStateMachine;
+import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
+import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
+
+@Configuration
+@EnableStateMachine
+public class SimpleEnumStateMachineConfiguration extends StateMachineConfigurerAdapter<ApplicationReviewStates, ApplicationReviewEvents> {
+
+    @Override
+    public void configure(StateMachineConfigurationConfigurer<ApplicationReviewStates, ApplicationReviewEvents> config)
+            throws Exception {
+        config
+                .withConfiguration()
+                .autoStartup(true)
+                .listener(new StateMachineListener());
+    }
+
+    @Override
+    public void configure(StateMachineStateConfigurer<ApplicationReviewStates, ApplicationReviewEvents> states) throws Exception {
+        states
+                .withStates()
+                .initial(ApplicationReviewStates.PEER_REVIEW)
+                .state(ApplicationReviewStates.PRINCIPAL_REVIEW)
+                .end(ApplicationReviewStates.APPROVED)
+                .end(ApplicationReviewStates.REJECTED);
+
+    }
+
+    @Override
+    public void configure(StateMachineTransitionConfigurer<ApplicationReviewStates, ApplicationReviewEvents> transitions) throws Exception {
+        transitions.withExternal()
+                .source(ApplicationReviewStates.PEER_REVIEW).target(ApplicationReviewStates.PRINCIPAL_REVIEW).event(ApplicationReviewEvents.APPROVE)
+                .and().withExternal()
+                .source(ApplicationReviewStates.PRINCIPAL_REVIEW).target(ApplicationReviewStates.APPROVED).event(ApplicationReviewEvents.APPROVE)
+                .and().withExternal()
+                .source(ApplicationReviewStates.PEER_REVIEW).target(ApplicationReviewStates.REJECTED).event(ApplicationReviewEvents.REJECT)
+                .and().withExternal()
+                .source(ApplicationReviewStates.PRINCIPAL_REVIEW).target(ApplicationReviewStates.REJECTED).event(ApplicationReviewEvents.REJECT);
+    }
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/SimpleStateMachineConfiguration.java

@@ -0,0 +1,146 @@
+package com.baeldung.spring.statemachine.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.statemachine.action.Action;
+import org.springframework.statemachine.config.EnableStateMachine;
+import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
+import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
+import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
+import org.springframework.statemachine.guard.Guard;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.logging.Logger;
+
+@Configuration
+@EnableStateMachine
+public class SimpleStateMachineConfiguration extends StateMachineConfigurerAdapter<String, String> {
+
+    private static final Logger LOGGER = Logger.getLogger(SimpleStateMachineConfiguration.class.getName());
+
+    @Override
+    public void configure(StateMachineConfigurationConfigurer<String, String> config) throws Exception {
+        config
+          .withConfiguration()
+          .autoStartup(true)
+          .listener(new StateMachineListener());
+    }
+
+    @Override
+    public void configure(StateMachineStateConfigurer<String, String> states) throws Exception {
+        states
+          .withStates()
+          .initial("SI")
+          .end("SF")
+          .states(new HashSet<>(Arrays.asList("S1", "S2")))
+          .stateEntry("S3", entryAction())
+          .stateExit("S3", exitAction())
+          .state("S4", executeAction(), errorAction())
+          .stateDo("S5", executeAction());
+
+    }
+
+    @Override
+    public void configure(StateMachineTransitionConfigurer<String, String> transitions) throws Exception {
+        transitions
+          .withExternal()
+          .source("SI")
+          .target("S1")
+          .event("E1")
+          .action(initAction())
+          .and()
+          .withExternal()
+          .source("S1")
+          .target("S2")
+          .event("E2")
+          .and()
+          .withExternal()
+          .source("SI")
+          .target("S3")
+          .event("E3")
+          .and()
+          .withExternal()
+          .source("S3")
+          .target("S4")
+          .event("E4")
+          .and()
+          .withExternal()
+          .source("S4")
+          .target("S5")
+          .event("E5")
+          .and()
+          .withExternal()
+          .source("S5")
+          .target("SF")
+          .event("end")
+          .guard(simpleGuard());
+    }
+
+    @Bean
+    public Guard<String, String> simpleGuard() {
+        return ctx -> {
+            int approvalCount = (int) ctx
+              .getExtendedState()
+              .getVariables()
+              .getOrDefault("approvalCount", 0);
+            return approvalCount > 0;
+        };
+    }
+
+    @Bean
+    public Action<String, String> entryAction() {
+        return ctx -> LOGGER.info("Entry " + ctx
+          .getTarget()
+          .getId());
+    }
+
+    @Bean
+    public Action<String, String> doAction() {
+        return ctx -> LOGGER.info("Do " + ctx
+          .getTarget()
+          .getId());
+    }
+
+    @Bean
+    public Action<String, String> executeAction() {
+        return ctx -> {
+            LOGGER.info("Execute " + ctx
+              .getTarget()
+              .getId());
+            int approvals = (int) ctx
+              .getExtendedState()
+              .getVariables()
+              .getOrDefault("approvalCount", 0);
+            approvals++;
+            ctx
+              .getExtendedState()
+              .getVariables()
+              .put("approvalCount", approvals);
+        };
+    }
+
+    @Bean
+    public Action<String, String> exitAction() {
+        return ctx -> LOGGER.info("Exit " + ctx
+          .getSource()
+          .getId() + " -> " + ctx
+          .getTarget()
+          .getId());
+    }
+
+    @Bean
+    public Action<String, String> errorAction() {
+        return ctx -> LOGGER.info("Error " + ctx
+          .getSource()
+          .getId() + ctx.getException());
+    }
+
+    @Bean
+    public Action<String, String> initAction() {
+        return ctx -> LOGGER.info(ctx
+          .getTarget()
+          .getId());
+    }
+}

spring-state-machine/src/main/java/com/baeldung/spring/statemachine/config/StateMachineListener.java

@@ -0,0 +1,16 @@
+package com.baeldung.spring.statemachine.config;
+
+import org.springframework.statemachine.listener.StateMachineListenerAdapter;
+import org.springframework.statemachine.state.State;
+
+import java.util.logging.Logger;
+
+public class StateMachineListener extends StateMachineListenerAdapter {
+
+    private static final Logger LOGGER = Logger.getLogger(StateMachineListener.class.getName());
+
+    @Override
+    public void stateChanged(State from, State to) {
+        LOGGER.info(() -> String.format("Transitioned from %s to %s%n", from == null ? "none" : from.getId(), to.getId()));
+    }
+}

spring-state-machine/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>