聊聊dubbo的DataStore

序

本文主要研究一下dubbo的DataStore

DataStore

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/store/DataStore.java

@SPI("simple")
public interface DataStore {
?
 /**
 * return a snapshot value of componentName
 */
 Map<String, Object> get(String componentName);
?
 Object get(String componentName, String key);
?
 void put(String componentName, String key, Object value);
?
 void remove(String componentName, String key);
?
}

• DataStore定义了get、put、remove方法，它有一个实现类为SimpleDataStore

SimpleDataStore

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/store/support/SimpleDataStore.java

public class SimpleDataStore implements DataStore {
?
 // <component name or id, <data-name, data-value>>
 private ConcurrentMap<String, ConcurrentMap<String, Object>> data =
 new ConcurrentHashMap<String, ConcurrentMap<String, Object>>();
?
 @Override
 public Map<String, Object> get(String componentName) {
 ConcurrentMap<String, Object> value = data.get(componentName);
 if (value == null) {
 return new HashMap<String, Object>();
 }
?
 return new HashMap<String, Object>(value);
 }
?
 @Override
 public Object get(String componentName, String key) {
 if (!data.containsKey(componentName)) {
 return null;
 }
 return data.get(componentName).get(key);
 }
?
 @Override
 public void put(String componentName, String key, Object value) {
 Map<String, Object> componentData = data.get(componentName);
 if (null == componentData) {
 data.putIfAbsent(componentName, new ConcurrentHashMap<String, Object>());
 componentData = data.get(componentName);
 }
 componentData.put(key, value);
 }
?
 @Override
 public void remove(String componentName, String key) {
 if (!data.containsKey(componentName)) {
 return;
 }
 data.get(componentName).remove(key);
 }
?
}

• SimpleDataStore使用ConcurrentHashMap来存储数据，每个key存储的是ConcurrentMap

实例

dubbo-2.7.2/dubbo-common/src/test/java/org/apache/dubbo/common/store/support/SimpleDataStoreTest.java

public class SimpleDataStoreTest {
 private SimpleDataStore dataStore = new SimpleDataStore();
?
 @Test
 public void testPutGet() throws Exception {
 assertNull(dataStore.get("xxx", "yyy"));
?
 dataStore.put("name", "key", "1");
 assertEquals("1", dataStore.get("name", "key"));
?
 assertNull(dataStore.get("xxx", "yyy"));
 }
?
 @Test
 public void testRemove() throws Exception {
 dataStore.remove("xxx", "yyy");
?
 dataStore.put("name", "key", "1");
 dataStore.remove("name", "key");
 assertNull(dataStore.get("name", "key"));
 }
?
 @Test
 public void testGetComponent() throws Exception {
 Map<String, Object> map = dataStore.get("component");
 assertTrue(map != null && map.isEmpty());
 dataStore.put("component", "key", "value");
 map = dataStore.get("component");
 assertTrue(map != null && map.size() == 1);
 dataStore.remove("component", "key");
 assertNotEquals(map, dataStore.get("component"));
 }
}

• 这里使用testPutGet、testRemove、testGetComponent进行了验证

小结

DataStore定义了get、put、remove方法，它有一个实现类为SimpleDataStore；SimpleDataStore使用ConcurrentHashMap来存储数据，每个key存储的是ConcurrentMap

doc

• DataStore