Add Config Center (#3020)

* Initialize config server module.

* Initialize config server module.

* Add TypeBasedSPI dependency.

* Modify Config Center related.

* Add Config Center Zookeeper related.

* Modify CuratorZookeeperConfigCenter and format pom.xml.

* Add Integration Test for Registry Center and Config Center.

* Modify Integration Test for Registry Center.

* Modify Config Center related functions.

* Modify Config Center related functions.

* Modify pom.xml.

* Modify services org.apache.shardingsphere.orchestration.config.api.ConfigCenter

* Modify pom.xml file.

* Add Unit test cases.

* format java file.

* Add Unit Test for ConfigCenterServiceLoader.

* Modify ConfigCenter.

sharding-orchestration/pom.xml

@@ -31,5 +31,6 @@
         <module>sharding-orchestration-core</module>
         <module>sharding-orchestration-reg</module>
         <module>sharding-orchestration-zookeeper-curator-integration-test</module>
+        <module>sharding-orchestration-config</module>
     </modules>
 </project>

sharding-orchestration/sharding-orchestration-config/pom.xml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to You 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">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <artifactId>sharding-orchestration</artifactId>
+        <groupId>org.apache.shardingsphere</groupId>
+        <version>4.0.0-RC3-SNAPSHOT</version>
+    </parent>
+    <artifactId>sharding-orchestration-config</artifactId>
+    <name>${project.artifactId}</name>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>sharding-orchestration-config-api</module>
+        <module>sharding-orchestration-config-zookeeper-curator</module>
+    </modules>
+</project>

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/pom.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to You 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">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <artifactId>sharding-orchestration-config</artifactId>
+        <groupId>org.apache.shardingsphere</groupId>
+        <version>4.0.0-RC3-SNAPSHOT</version>
+    </parent>
+    <artifactId>sharding-orchestration-config-api</artifactId>
+    <name>${project.artifactId}</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.shardingsphere</groupId>
+            <artifactId>sharding-core-api</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+    </dependencies>
+</project>

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/src/main/java/org/apache/shardingsphere/orchestration/config/api/ConfigCenter.java

@@ -0,0 +1,111 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.shardingsphere.orchestration.config.api;
+
+import org.apache.shardingsphere.orchestration.config.listener.DataChangedEventListener;
+import org.apache.shardingsphere.spi.TypeBasedSPI;
+
+import java.util.List;
+
+/**
+ * Config center.
+ * 
+ * @author wangguangyuan
+ */
+public interface ConfigCenter extends TypeBasedSPI {
+
+    /**
+     * Initialize config center.
+     * 
+     * @param config config center configuration
+     */
+    void init(ConfigCenterConfiguration config);
+
+    /**
+     * Get data from config center.
+     * 
+     * <p>Maybe use cache if existed.</p>
+     * 
+     * @param key key of data
+     * @return value of data
+     */
+    String get(String key);
+
+    /**
+     * Get data from config center directly.
+     * 
+     * <p>Cannot use cache.</p>
+     *
+     * @param key key of data
+     * @return value of data
+     */
+    String getDirectly(String key);
+
+    /**
+     * Judge data is existed or not.
+     * 
+     * @param key key of data
+     * @return data is existed or not
+     */
+    boolean isExisted(String key);
+
+    /**
+     * Get node's sub-nodes list.
+     *
+     * @param key key of data
+     * @return sub-nodes name list
+     */
+    List<String> getChildrenKeys(String key);
+
+    /**
+     * Persist data.
+     * 
+     * @param key key of data
+     * @param value value of data
+     */
+    void persist(String key, String value);
+
+    /**
+     * Update data.
+     *
+     * @param key key of data
+     * @param value value of data
+     */
+    void update(String key, String value);
+
+    /**
+     * Persist ephemeral data.
+     *
+     * @param key key of data
+     * @param value value of data
+     */
+    void persistEphemeral(String key, String value);
+
+    /**
+     * Watch key or path of the config server.
+     *
+     * @param key key of data
+     * @param dataChangedEventListener data changed event listener
+     */
+    void watch(String key, DataChangedEventListener dataChangedEventListener);
+
+    /**
+     * Close.
+      */
+    void close();
+}

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/src/main/java/org/apache/shardingsphere/orchestration/config/api/ConfigCenterConfiguration.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.shardingsphere.orchestration.config.api;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.apache.shardingsphere.api.config.TypeBasedSPIConfiguration;
+
+import java.util.Properties;
+
+/**
+ * Config center configuration.
+ *
+ * @author wangguangyuan
+ */
+@Getter
+@Setter
+public final class ConfigCenterConfiguration extends TypeBasedSPIConfiguration {
+
+    /**
+     * Server list of config center.
+     */
+    private String serverLists;
+
+    /**
+     * Namespace of config center.
+     */
+    private String namespace;
+
+    /**
+     * Digest of config center.
+     */
+    private String digest;
+
+    /**
+     * Operation timeout time in milliseconds.
+     */
+    private int operationTimeoutMilliseconds = 500;
+
+    /**
+     * Max number of times to retry.
+     */
+    private int maxRetries = 3;
+
+    /**
+     * Time interval in milliseconds on each retry.
+     */
+    private int retryIntervalMilliseconds = 500;
+
+    /**
+     * Time to live in seconds of ephemeral keys.
+     */
+    private int timeToLiveSeconds = 60;
+
+    public ConfigCenterConfiguration(final String type) {
+        super(type);
+    }
+
+    public ConfigCenterConfiguration(final String type, final Properties properties) {
+        super(type, properties);
+    }
+}

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/src/main/java/org/apache/shardingsphere/orchestration/config/exception/ConfigCenterException.java

@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.shardingsphere.orchestration.config.exception;
+
+/**
+ * Config center exception.
+ * 
+ * @author wangguangyuan
+ */
+public final class ConfigCenterException extends RuntimeException {
+
+    private static final long serialVersionUID = -6417179023552012152L;
+
+    public ConfigCenterException(final String errorMessage, final Object... args) {
+        super(String.format(errorMessage, args));
+    }
+
+    public ConfigCenterException(final Exception cause) {
+        super(cause);
+    }
+}

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/src/main/java/org/apache/shardingsphere/orchestration/config/listener/DataChangedEvent.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.shardingsphere.orchestration.config.listener;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+/**
+ * Data changed event.
+ *
+ * @author wangguangyuan
+ */
+@RequiredArgsConstructor
+@Getter
+public final class DataChangedEvent {
+
+    private final String key;
+
+    private final String value;
+
+    private final ChangedType changedType;
+
+    /**
+     * Data changed type.
+     */
+    public enum ChangedType {
+
+        UPDATED, DELETED, IGNORED
+    }
+}

sharding-orchestration/sharding-orchestration-config/sharding-orchestration-config-api/src/main/java/org/apache/shardingsphere/orchestration/config/listener/DataChangedEventListener.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.shardingsphere.orchestration.config.listener;
+
+/**
+ * Listener for data changed event.
+ *
+ * @author wangguangyuan
+ */
+public interface DataChangedEventListener {
+
+    /**
+     * Fire when data changed.
+     * 
+     * @param dataChangedEvent data changed event
+     */
+    void onChange(DataChangedEvent dataChangedEvent);
+}