Provide saga functionality (based on interceptors)

all/pom.xml

@@ -202,6 +202,11 @@
             <artifactId>seata-tcc</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.seata</groupId>
+            <artifactId>seata-saga</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.seata</groupId>
             <artifactId>seata-tm</artifactId>
@@ -524,6 +529,7 @@
                                     <include>io.seata:seata-sofa-rpc</include>
                                     <include>io.seata:seata-spring</include>
                                     <include>io.seata:seata-tcc</include>
+				    <include>io.seata:seata-saga</include>
                                     <include>io.seata:seata-tm</include>
                                     <include>io.seata:seata-codec-seata</include>
                                     <include>io.seata:seata-codec-protobuf</include>

common/src/main/java/io/seata/common/Constants.java

@@ -84,21 +84,40 @@ public class Constants {
      */
     public final static String TCC_METHOD_RESULT = "result";
 
+    /**
+     * The constant SAGA_METHOD_RESULT.
+     */
+    public final static String  SAGA_METHOD_RESULT    = "result";
+
     /**
      * The constant TCC_METHOD_ARGUMENTS.
      */
     public final static String TCC_METHOD_ARGUMENTS = "arguments";
 
+    /**
+     */
+    public final static String  SAGA_METHOD_ARGUMENTS = "arguments";
+
     /**
      * transaction context
      */
-    public final static String TCC_ACTIVITY_CONTEXT = "activityContext";
+    public final static String  TCC_ACTIVITY_CONTEXT  = "activityContext";
 
+    /**
+     * transaction context
+     */
+    public final static String  SAGA_ACTIVITY_CONTEXT  = "activityContext";
+
     /**
      * branch context
      */
     public final static String TCC_ACTION_CONTEXT = "actionContext";
 
+    /**
+     * branch context
+     */
+    public final static String  SAGA_ACTION_CONTEXT   = "actionContext";
+
     /**
      * default charset name
      */

core/src/main/java/io/seata/core/context/RootContext.java

@@ -17,6 +17,7 @@
 
 import io.seata.common.exception.ShouldNeverHappenException;
 
+import io.seata.common.util.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -32,21 +33,32 @@ public class RootContext {
     /**
      * The constant KEY_XID.
      */
-    public static final String KEY_XID = "TX_XID";
-
-    public static final String KEY_GLOBAL_LOCK_FLAG = "TX_LOCK";
-
-    private static ContextCore CONTEXT_HOLDER = ContextCoreLoader.load();
-
+    public static final String  KEY_XID              = "TX_XID";
+
+    public static final String  KEY_XID_TYPE         = "TX_XID_TYPE";
+
+    public static final String  KEY_GLOBAL_LOCK_FLAG = "TX_LOCK";
+
+    private static ContextCore  CONTEXT_HOLDER       = ContextCoreLoader.load();
+
     /**
      * Gets xid.
      *
      * @return the xid
      */
     public static String getXID() {
-        return CONTEXT_HOLDER.get(KEY_XID);
-    }
+        String xid =  CONTEXT_HOLDER.get(KEY_XID);
+        if(StringUtils.isNotBlank(xid)){
+            return xid;
+        }
 
+        String xidType = CONTEXT_HOLDER.get(KEY_XID_TYPE);
+        if(StringUtils.isNotBlank(xidType)){
+            return xidType.split("_")[0];
+        }
+        return null;
+    }
+
     /**
      * Bind.
      *
@@ -59,6 +71,18 @@ public static void bind(String xid) {
         CONTEXT_HOLDER.put(KEY_XID, xid);
     }
 
+    /**
+     * Bind type
+     *
+     * @param xidType
+     */
+    public static void bindType(String xidType) {
+        if (LOGGER.isDebugEnabled()) {
+            LOGGER.debug("bind type " + xidType);
+        }
+        CONTEXT_HOLDER.put(KEY_XID_TYPE, xidType);
+    }
+
     /**
      * declare local transactions will use global lock check for update/delete/insert/selectForUpdate SQL
      */
@@ -84,7 +108,20 @@ public static String unbind() {
         }
         return xid;
     }
-
+
+    /**
+     * Unbind temporary string
+     *
+     * @return the string
+     */
+    public static String unbindType() {
+        String xidType = CONTEXT_HOLDER.remove(KEY_XID_TYPE);
+        if (LOGGER.isDebugEnabled()) {
+            LOGGER.debug("unbind type " + xidType);
+        }
+        return xidType;
+    }
+
     public static void unbindGlobalLockFlag() {
         String lockFlag = CONTEXT_HOLDER.remove(KEY_GLOBAL_LOCK_FLAG);
         if (LOGGER.isDebugEnabled() && lockFlag != null) {

core/src/main/java/io/seata/core/model/BranchType.java

@@ -27,7 +27,13 @@ public enum BranchType {
      */
     // AT Branch
     AT,
-
+
+    /**
+     * The At.
+     */
+    // AT Branch
+    SAGA,
+
     /**
      * The TCC.
      */

pom.xml

@@ -39,6 +39,7 @@
         <module>server</module>
         <module>spring</module>
         <module>tcc</module>
+        <module>saga</module>
         <module>test</module>
         <module>tm</module>
         <module>metrics</module>

saga/README.MD

@@ -0,0 +1,69 @@
+### TCC
+
+
+#### TCC 简介
+
+在2PC（两阶段提交）协议中，事务管理器分两阶段协调资源管理，资源管理器对外提供了3个操作，分别是一阶段的准备操作，二阶段的提交操作和回滚操作；
+
+TCC服务作为一种事务资源，遵循两阶段提交协议，由业务层面自定义，需要用户根据业务逻辑编码实现；其包含Try、Confirm 和 Cancel 3个操作，其中Try操作对应分布式事务一阶段的准备，Confirm操作对应分布式事务二阶段提交，Cancel对应分布式事务二阶段回滚：
+
+- Try：
+
+资源的检查和预留；
+
+- Comfirm：
+
+使用预留的资源，完成真正的业务操作；要求Try成功Confirm 一定要能成功；
+
+- Cancel：
+
+释放预留资源；
+
+
+TCC的3个方法均由用户根据业务场景编码实现，并对外发布成微服务，供事务管理器调用；事务管理器在一阶段调用TCC的Try方法，在二阶段提交时调用Confirm方法，在二阶段回滚时调用Cancel方法。
+
+
+#### TCC实现
+
+##### 1、TCC微服务
+
+TCC服务由用户编码实现并对外发布成微服务，目前支持3种形式的TCC微服务，分别是：
+
+- SofaRpc 服务
+
+用户将实现的TCC操作对外发布成 SofaRpc 服务，事务管理器通过订阅SofaRpc服务，来协调TCC资源；
+
+- Dubbo 服务
+
+将TCC发布成dubbo服务，事务管理器订阅dubbo服务，来协调TCC资源；
+
+- Local TCC
+
+本地普通的TCC Bean，非远程服务；事务管理器通过本地方法调用，来协调TCC 资源；
+
+##### 2、TCC资源动态代理
+
+对TCC服务进行动态代理，GlobalTransactionScanner中当扫描到TCC 服务的 ‘reference’时，会对其进行动态代理；
+
+TCC 动态代理的主要功能是：生成TCC运行时上下文、透传业务参数、注册分支事务记录；
+
+#### 模块说明
+
+seata-tcc 包含TCC主要代码：
+
+- interceptor：TCC 动态代理；
+
+- remoting：TCC微服务扫描、RPC协议解析、TCC资源注册；
+
+- TccResourceManager、RMHandlerTCC： TCC资源管理器；
+
+
+
+
+#### 其他说明：
+
+本此为了区分AT、TCC 2种资源类型，在客户端和服务端通信的接口中，均添加了 BranchType 参数；
+
+
+
+

saga/pom.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~  Copyright 1999-2019 Seata.io Group.
+  ~
+  ~  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.
+  -->
+
+<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">
+    <parent>
+        <groupId>io.seata</groupId>
+        <artifactId>seata-parent</artifactId>
+        <version>${revision}</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>seata-saga</artifactId>
+    <packaging>jar</packaging>
+    <name>seata-saga ${project.version}</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>seata-core</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>seata-rm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+    </dependencies>
+
+
+</project>

saga/src/main/java/io/seata/rm/saga/RMHandlerSAGA.java

@@ -0,0 +1,51 @@
+/*
+ *  Copyright 1999-2019 Seata.io Group.
+ *
+ *  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 io.seata.rm.saga;
+
+import io.seata.core.model.BranchType;
+import io.seata.core.model.ResourceManager;
+import io.seata.core.protocol.transaction.UndoLogDeleteRequest;
+import io.seata.rm.AbstractRMHandler;
+import io.seata.rm.DefaultResourceManager;
+
+/**
+ * The type Rm handler saga.
+ *
+ * @author zhangsen
+ */
+public class RMHandlerSAGA extends AbstractRMHandler {
+
+    @Override
+    public void handle(UndoLogDeleteRequest request) {
+        //DO nothing
+    }
+
+    /**
+     * get TCC resource manager
+     *
+     * @return
+     */
+    @Override
+    protected ResourceManager getResourceManager() {
+        return DefaultResourceManager.get().getResourceManager(BranchType.SAGA);
+    }
+
+    @Override
+    public BranchType getBranchType() {
+        return BranchType.SAGA;
+    }
+
+}