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