add statemachine

cola-statemachine/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.alibaba.cola</groupId>
+    <artifactId>statemachine</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <java.version>1.8</java.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+    </properties>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.9</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-core</artifactId>
+            <version>1.2.3</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.2.3</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.16.22</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/Action.java

@@ -0,0 +1,21 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * Generic strategy interface used by a state machine to respond
+ * events by executing an {@code Action} with a {@link StateContext}.
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 2:51 PM
+ */
+public interface Action<S, E, C> {
+
+//    /**
+//     * Execute action with a {@link StateContext}.
+//     *
+//     * @param context the state context
+//     */
+//    void execute(StateContext<S, E> context);
+
+    public void execute(S from, S to, E event, C context);
+
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/Condition.java

@@ -0,0 +1,20 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * Condition
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 2:50 PM
+ */
+public interface Condition<C> {
+
+    /**
+     * @param context context object
+     * @return whether the context satisfied current condition
+     */
+    boolean isSatisfied(C context);
+
+    default String name(){
+        return this.getClass().getSimpleName();
+    }
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/State.java

@@ -0,0 +1,38 @@
+package com.alibaba.cola.statemachine;
+
+import com.alibaba.cola.statemachine.impl.TransitionType;
+
+import java.util.Collection;
+import java.util.Optional;
+
+/**
+ * State
+ *
+ * @param <S> the type of state
+ * @param <E> the type of event
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 2:12 PM
+ */
+public interface State<S,E,C> extends Visitable{
+
+    /**
+     * Gets the state identifier.
+     *
+     * @return the state identifiers
+     */
+    S getId();
+
+    /**
+     * Add transition to the state
+     * @param event the event of the Transition
+     * @param target the target of the transition
+     * @return
+     */
+    Transition<S,E,C> addTransition(E event, State<S, E, C> target, TransitionType transitionType);
+
+    Optional<Transition<S,E,C>> getTransition(E event);
+
+    Collection<Transition<S,E,C>> getTransitions();
+
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/StateContext.java

@@ -0,0 +1,23 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * StateContext
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 2:49 PM
+ */
+public interface StateContext<S, E, C> {
+    /**
+     * Gets the transition.
+     *
+     * @return the transition
+     */
+    Transition<S, E, C> getTransition();
+
+    /**
+     * Gets the state machine.
+     *
+     * @return the state machine
+     */
+    StateMachine<S, E, C> getStateMachine();
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/StateMachine.java

@@ -0,0 +1,37 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * StateMachine
+ *
+ * @author Frank Zhang
+ *
+ * @param <S> the type of state
+ * @param <E> the type of event
+ * @param <C> the user defined context
+ * @date 2020-02-07 2:13 PM
+ */
+public interface StateMachine<S, E, C> extends Visitable{
+
+    /**
+     * Send an event {@code E} to the state machine.
+     *
+     * @param sourceState the source state
+     * @param event the event to send
+     * @param ctx the user defined context
+     * @return the target state
+     */
+     S fireEvent(S sourceState, E event, C ctx);
+
+    /**
+     * MachineId is the identifier for a State Machine
+     * @return
+     */
+    String getMachineId();
+
+    /**
+     * Use visitor pattern to display the structure of the state machine
+     */
+    void showStateMachine();
+
+    void generatePlantUML();
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/StateMachineFactory.java

@@ -0,0 +1,32 @@
+package com.alibaba.cola.statemachine;
+
+import com.alibaba.cola.statemachine.impl.StateMachineException;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * StateMachineFactory
+ *
+ * @author Frank Zhang
+ * @date 2020-02-08 10:21 PM
+ */
+public class StateMachineFactory {
+    static Map<String /* machineId */, StateMachine> stateMachineMap = new ConcurrentHashMap<>();
+
+    public static void register(StateMachine stateMachine){
+        String machineId = stateMachine.getMachineId();
+        if(stateMachineMap.get(machineId) != null){
+            throw new StateMachineException("The state machine with id ["+machineId+"] is already built, no need to build again");
+        }
+        stateMachineMap.put(stateMachine.getMachineId(), stateMachine);
+    }
+
+    public static StateMachine get(String machineId){
+        StateMachine stateMachine = stateMachineMap.get(machineId);
+        if(stateMachine == null){
+            throw new StateMachineException("There is no stateMachine instance for "+machineId+", please build it first");
+        }
+        return stateMachine;
+    }
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/Transition.java

@@ -0,0 +1,65 @@
+package com.alibaba.cola.statemachine;
+
+import com.alibaba.cola.statemachine.impl.TransitionType;
+
+/**
+ * {@code Transition} is something what a state machine associates with a state
+ * changes.
+ *
+ * @author Frank Zhang
+ *
+ * @param <S> the type of state
+ * @param <E> the type of event
+ * @param <C> the type of user defined context, which is used to hold application data
+ *
+ * @date 2020-02-07 2:20 PM
+ */
+public interface Transition<S, E, C>{
+    /**
+     * Gets the source state of this transition.
+     *
+     * @return the source state
+     */
+    State<S,E,C> getSource();
+
+    void setSource(State<S, E, C> state);
+
+    E getEvent();
+
+    void setEvent(E event);
+
+    void setType(TransitionType type);
+    /**
+     * Gets the target state of this transition.
+     *
+     * @return the target state
+     */
+    State<S,E,C> getTarget();
+
+    void setTarget(State<S, E, C> state);
+
+    /**
+     * Gets the guard of this transition.
+     *
+     * @return the guard
+     */
+    Condition<C> getCondition();
+
+    void setCondition(Condition<C> condition);
+
+    Action<S,E,C> getAction();
+
+    void setAction(Action<S, E, C> action);
+
+    /**
+     * Do transition from source state to target state.
+     *
+     * @return the target state
+     */
+
+    State<S,E,C> transit(C ctx);
+    /**
+     * Verify transition correctness
+     */
+    void verify();
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/Visitable.java

@@ -0,0 +1,11 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * Visitable
+ *
+ * @author Frank Zhang
+ * @date 2020-02-08 8:41 PM
+ */
+public interface Visitable {
+    void accept(final Visitor visitor);
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/Visitor.java

@@ -0,0 +1,29 @@
+package com.alibaba.cola.statemachine;
+
+/**
+ * Visitor
+ *
+ * @author Frank Zhang
+ * @date 2020-02-08 8:41 PM
+ */
+public interface Visitor {
+    /**
+     * @param visitable the element to be visited.
+     */
+    void visitOnEntry(StateMachine<?, ?, ?> visitable);
+
+    /**
+     * @param visitable the element to be visited.
+     */
+    void visitOnExit(StateMachine<?, ?, ?> visitable);
+
+    /**
+     * @param visitable the element to be visited.
+     */
+    void visitOnEntry(State<?, ?, ?> visitable);
+
+    /**
+     * @param visitable the element to be visited.
+     */
+    void visitOnExit(State<?, ?, ?> visitable);
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/builder/ExternalTransitionBuilder.java

@@ -0,0 +1,17 @@
+package com.alibaba.cola.statemachine.builder;
+
+/**
+ * ExternalTransitionBuilder
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 6:11 PM
+ */
+public interface ExternalTransitionBuilder<S, E, C> {
+    /**
+     * Build transition source state.
+     * @param stateId id of state
+     * @return from clause builder
+     */
+    From<S, E, C> from(S stateId);
+
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/builder/ExternalTransitionsBuilder.java

@@ -0,0 +1,13 @@
+package com.alibaba.cola.statemachine.builder;
+
+/**
+ * ExternalTransitionsBuilder
+ *
+ * This builder is for multiple transitions, currently only support multiple sources <----> one target
+ *
+ * @author Frank Zhang
+ * @date 2020-02-08 7:41 PM
+ */
+public interface ExternalTransitionsBuilder<S, E, C> {
+    From<S, E, C> fromAmong(S... stateIds);
+}

cola-statemachine/src/main/java/com/alibaba/cola/statemachine/builder/From.java

@@ -0,0 +1,17 @@
+package com.alibaba.cola.statemachine.builder;
+
+/**
+ * From
+ *
+ * @author Frank Zhang
+ * @date 2020-02-07 6:13 PM
+ */
+public interface From<S, E, C> {
+    /**
+     * Build transition target state and return to clause builder
+     * @param stateId id of state
+     * @return To clause builder
+     */
+    To<S, E, C> to(S stateId);
+
+}