Implement custom trace repository

- Upgrade to boot 2.0.0.RC1
- Copy original boot's tracing features to get used
  as a base impl for statemachine.
- Fix samples, tests.
- Fixes #491

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/actuate/InMemoryStateMachineTraceRepository.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * 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 org.springframework.statemachine.boot.actuate;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Date;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * In-memory implementation of {@link StateMachineTraceRepository}.
+ *
+ * @author Janne Valkealahti
+ *
+ */
+public class InMemoryStateMachineTraceRepository implements StateMachineTraceRepository {
+
+	private int capacity = 100;
+	private boolean reverse = true;
+	private final List<StateMachineTrace> traces = new LinkedList<StateMachineTrace>();
+
+	/**
+	 * Flag to say that the repository lists traces in reverse order.
+	 * @param reverse flag value (default true)
+	 */
+	public void setReverse(boolean reverse) {
+		synchronized (this.traces) {
+			this.reverse = reverse;
+		}
+	}
+
+	/**
+	 * Set the capacity of the in-memory repository.
+	 * @param capacity the capacity
+	 */
+	public void setCapacity(int capacity) {
+		synchronized (this.traces) {
+			this.capacity = capacity;
+		}
+	}
+
+	@Override
+	public List<StateMachineTrace> findAll() {
+		synchronized (this.traces) {
+			return Collections.unmodifiableList(new ArrayList<StateMachineTrace>(this.traces));
+		}
+	}
+
+	@Override
+	public void add(Map<String, Object> map) {
+		StateMachineTrace trace = new StateMachineTrace(new Date(), map);
+		synchronized (this.traces) {
+			while (this.traces.size() >= this.capacity) {
+				this.traces.remove(this.reverse ? this.capacity - 1 : 0);
+			}
+			if (this.reverse) {
+				this.traces.add(0, trace);
+			}
+			else {
+				this.traces.add(trace);
+			}
+		}
+	}
+}

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/actuate/StateMachineTrace.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * 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 org.springframework.statemachine.boot.actuate;
+
+import java.util.Date;
+import java.util.Map;
+
+import org.springframework.util.Assert;
+
+/**
+ * A value object representing a statemachine trace event: at a particular time
+ * with a simple (map) information.
+ *
+ * @author Janne Valkealahti
+ *
+ */
+public final class StateMachineTrace {
+
+	private final Date timestamp;
+	private final Map<String, Object> info;
+
+	/**
+	 * Instantiate a new {@code StateMachineTrace}.
+	 *
+	 * @param timestamp the timestamp
+	 * @param info the trace info
+	 */
+	public StateMachineTrace(Date timestamp, Map<String, Object> info) {
+		super();
+		Assert.notNull(timestamp, "Timestamp must not be null");
+		Assert.notNull(info, "Info must not be null");
+		this.timestamp = timestamp;
+		this.info = info;
+	}
+
+	/**
+	 * Gets a timestamp
+	 *
+	 * @return a trace timestamp
+	 */
+	public Date getTimestamp() {
+		return this.timestamp;
+	}
+
+	/**
+	 * Gets a trace info.
+	 *
+	 * @return a trace info
+	 */
+	public Map<String, Object> getInfo() {
+		return this.info;
+	}
+}

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/actuate/StateMachineTraceEndpoint.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * 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 org.springframework.statemachine.boot.actuate;
+
+import java.util.List;
+
+import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
+import org.springframework.boot.actuate.endpoint.annotation.ReadOperation;
+import org.springframework.util.Assert;
+
+/**
+ * {@code Endpoint} to expose {@link StateMachineTrace} information.
+ *
+ * @author Janne Valkealahti
+ *
+ */
+@Endpoint(id = "statemachinetrace")
+public class StateMachineTraceEndpoint {
+
+	private final StateMachineTraceRepository repository;
+
+	/**
+	 * Create a new {@link StateMachineTraceEndpoint} instance.
+	 *
+	 * @param repository the trace repository
+	 */
+	public StateMachineTraceEndpoint(StateMachineTraceRepository repository) {
+		Assert.notNull(repository, "Repository must not be null");
+		this.repository = repository;
+	}
+
+	@ReadOperation
+	public List<StateMachineTrace> invoke() {
+		return this.repository.findAll();
+	}
+}

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/actuate/StateMachineTraceRepository.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * 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 org.springframework.statemachine.boot.actuate;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A repository for {@link StateMachineTrace}s.
+ *
+ * @author Janne Valkealahti
+ *
+ */
+public interface StateMachineTraceRepository {
+
+	/**
+	 * Find all {@link StateMachineTrace} objects contained in the repository.
+	 *
+	 * @return the results
+	 */
+	List<StateMachineTrace> findAll();
+
+	/**
+	 * Add a new {@link StateMachineTrace} object at the current time.
+	 *
+	 * @param traceInfo trace information
+	 */
+	void add(Map<String, Object> traceInfo);
+}

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/autoconfigure/StateMachineAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,14 +16,18 @@
 package org.springframework.statemachine.boot.autoconfigure;
 
 import org.springframework.beans.factory.ObjectProvider;
-import org.springframework.boot.actuate.trace.TraceRepository;
+import org.springframework.boot.actuate.autoconfigure.web.ManagementContextConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.statemachine.boot.StateMachineProperties;
+import org.springframework.statemachine.boot.actuate.InMemoryStateMachineTraceRepository;
+import org.springframework.statemachine.boot.actuate.StateMachineTraceEndpoint;
+import org.springframework.statemachine.boot.actuate.StateMachineTraceRepository;
 import org.springframework.statemachine.boot.support.BootStateMachineMonitor;
 
 import io.micrometer.core.instrument.MeterRegistry;
@@ -36,25 +40,44 @@ import io.micrometer.core.instrument.MeterRegistry;
  */
 @Configuration
 @EnableConfigurationProperties({ StateMachineProperties.class })
+@ConditionalOnClass(MeterRegistry.class)
+@ConditionalOnProperty(prefix = "spring.statemachine.monitor", name = "enabled", havingValue = "true", matchIfMissing = true)
 public class StateMachineAutoConfiguration {
 
+	@ManagementContextConfiguration
+	public static class StateMachineTraceEndpointConfiguration {
+
+	    @Bean
+	    public StateMachineTraceEndpoint stateMachieTraceEndpoint(StateMachineTraceRepository stateMachineTraceRepository) {
+			return new StateMachineTraceEndpoint(stateMachineTraceRepository);
+	    }
+	}
+
+	@Configuration
+	public static class StateMachineTraceRepositoryConfiguration {
+
+	    @ConditionalOnMissingBean(StateMachineTraceRepository.class)
+	    @Bean
+	    public InMemoryStateMachineTraceRepository stateMachineTraceRepository() {
+	            return new InMemoryStateMachineTraceRepository();
+	    }
+	}
+
 	@Configuration
-	@ConditionalOnClass(MeterRegistry.class)
-	@ConditionalOnProperty(prefix = "spring.statemachine.monitor", name = "enabled", havingValue = "true", matchIfMissing = true)
 	public static class StateMachineMonitoringConfiguration {
 
 		private final MeterRegistry meterRegistry;
-		private final TraceRepository traceRepository;
+		private final StateMachineTraceRepository stateMachineTraceRepository;
 
 		public StateMachineMonitoringConfiguration(ObjectProvider<MeterRegistry> meterRegistryProvider,
-				ObjectProvider<TraceRepository> traceRepositoryProvider) {
+				ObjectProvider<StateMachineTraceRepository> traceRepositoryProvider) {
 			this.meterRegistry = meterRegistryProvider.getIfAvailable();
-			this.traceRepository = traceRepositoryProvider.getIfAvailable();
+			this.stateMachineTraceRepository = traceRepositoryProvider.getIfAvailable();
 		}
 
 		@Bean
 		public BootStateMachineMonitor<?, ?> bootStateMachineMonitor() {
-			return new BootStateMachineMonitor<>(meterRegistry, traceRepository);
+			return new BootStateMachineMonitor<>(meterRegistry, stateMachineTraceRepository);
 		}
 	}
 }

spring-statemachine-boot/src/main/java/org/springframework/statemachine/boot/support/BootStateMachineMonitor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,9 +19,9 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
-import org.springframework.boot.actuate.trace.TraceRepository;
 import org.springframework.statemachine.StateMachine;
 import org.springframework.statemachine.action.Action;
+import org.springframework.statemachine.boot.actuate.StateMachineTraceRepository;
 import org.springframework.statemachine.monitor.AbstractStateMachineMonitor;
 import org.springframework.statemachine.monitor.StateMachineMonitor;
 import org.springframework.statemachine.state.State;
@@ -44,18 +44,19 @@ import io.micrometer.core.instrument.Timer;
  */
 public class BootStateMachineMonitor<S, E> extends AbstractStateMachineMonitor<S, E> {
 
-	private final TraceRepository traceRepository;
+	private final StateMachineTraceRepository traceRepository;
 	private final MeterRegistry meterRegistry;
 
 	/**
 	 * Instantiates a new boot state machine monitor.
 	 *
 	 * @param meterRegistry the meter registry
-	 * @param traceRepository the trace repository
+	 * @param stateMachineTraceRepository the statemachine trace repository
 	 */
-	public BootStateMachineMonitor(MeterRegistry meterRegistry, TraceRepository traceRepository) {
+	public BootStateMachineMonitor(MeterRegistry meterRegistry,
+			StateMachineTraceRepository stateMachineTraceRepository) {
 		this.meterRegistry = meterRegistry;
-		this.traceRepository = traceRepository;
+		this.traceRepository = stateMachineTraceRepository;
 	}
 
 	@Override