init

sentinel/sentinel-extension/sentinel-datasource-extension/pom.xml

@@ -0,0 +1,27 @@
+<?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>
+
+    <parent>
+        <groupId>com.alibaba.csp</groupId>
+        <artifactId>sentinel-extension</artifactId>
+        <version>1.8.3</version>
+    </parent>
+
+    <artifactId>sentinel-datasource-extension</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.alibaba.csp</groupId>
+            <artifactId>sentinel-core</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/AbstractDataSource.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import com.alibaba.csp.sentinel.property.DynamicSentinelProperty;
+import com.alibaba.csp.sentinel.property.SentinelProperty;
+
+/**
+ * The abstract readable data source provides basic functionality for loading and parsing config.
+ *
+ * @param <S> source data type
+ * @param <T> target data type
+ * @author Carpenter Lee
+ * @author Eric Zhao
+ */
+public abstract class AbstractDataSource<S, T> implements ReadableDataSource<S, T> {
+
+    protected final Converter<S, T> parser;
+    protected final SentinelProperty<T> property;
+
+    public AbstractDataSource(Converter<S, T> parser) {
+        if (parser == null) {
+            throw new IllegalArgumentException("parser can't be null");
+        }
+        this.parser = parser;
+        this.property = new DynamicSentinelProperty<T>();
+    }
+
+    @Override
+    public T loadConfig() throws Exception {
+        return loadConfig(readSource());
+    }
+
+    public T loadConfig(S conf) throws Exception {
+        T value = parser.convert(conf);
+        return value;
+    }
+
+    @Override
+    public SentinelProperty<T> getProperty() {
+        return property;
+    }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/AutoRefreshDataSource.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import com.alibaba.csp.sentinel.concurrent.NamedThreadFactory;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+/**
+ * A {@link ReadableDataSource} automatically fetches the backend data.
+ *
+ * @param <S> source data type
+ * @param <T> target data type
+ * @author Carpenter Lee
+ */
+public abstract class AutoRefreshDataSource<S, T> extends AbstractDataSource<S, T> {
+
+    private ScheduledExecutorService service;
+    protected long recommendRefreshMs = 3000;
+
+    public AutoRefreshDataSource(Converter<S, T> configParser) {
+        super(configParser);
+        startTimerService();
+    }
+
+    public AutoRefreshDataSource(Converter<S, T> configParser, final long recommendRefreshMs) {
+        super(configParser);
+        if (recommendRefreshMs <= 0) {
+            throw new IllegalArgumentException("recommendRefreshMs must > 0, but " + recommendRefreshMs + " get");
+        }
+        this.recommendRefreshMs = recommendRefreshMs;
+        startTimerService();
+    }
+
+    @SuppressWarnings("PMD.ThreadPoolCreationRule")
+    private void startTimerService() {
+        service = Executors.newScheduledThreadPool(1,
+            new NamedThreadFactory("sentinel-datasource-auto-refresh-task", true));
+        service.scheduleAtFixedRate(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    if (!isModified()) {
+                        return;
+                    }
+                    T newValue = loadConfig();
+                    getProperty().updateValue(newValue);
+                } catch (Throwable e) {
+                    RecordLog.info("loadConfig exception", e);
+                }
+            }
+        }, recommendRefreshMs, recommendRefreshMs, TimeUnit.MILLISECONDS);
+    }
+
+    @Override
+    public void close() throws Exception {
+        if (service != null) {
+            service.shutdownNow();
+            service = null;
+        }
+    }
+
+    protected boolean isModified() {
+        return true;
+    }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/Converter.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+/**
+ * Convert an object from source type {@code S} to target type {@code T}.
+ *
+ * @author leyou
+ * @author Eric Zhao
+ */
+public interface Converter<S, T> {
+
+    /**
+     * Convert {@code source} to the target type.
+     *
+     * @param source the source object
+     * @return the target object
+     */
+    T convert(S source);
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/EmptyDataSource.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import com.alibaba.csp.sentinel.property.NoOpSentinelProperty;
+import com.alibaba.csp.sentinel.property.SentinelProperty;
+
+/**
+ * A {@link ReadableDataSource} based on nothing. {@link EmptyDataSource#getProperty()} will always return the same cached
+ * {@link SentinelProperty} that doing nothing.
+ * <br/>
+ * This class is used when we want to use default settings instead of configs from the {@link ReadableDataSource}.
+ *
+ * @author leyou
+ */
+public final class EmptyDataSource implements ReadableDataSource<Object, Object> {
+
+    public static final ReadableDataSource<Object, Object> EMPTY_DATASOURCE = new EmptyDataSource();
+
+    private static final SentinelProperty<Object> PROPERTY = new NoOpSentinelProperty();
+
+    private EmptyDataSource() { }
+
+    @Override
+    public Object loadConfig() throws Exception {
+        return null;
+    }
+
+    @Override
+    public Object readSource() throws Exception {
+        return null;
+    }
+
+    @Override
+    public SentinelProperty<Object> getProperty() {
+        return PROPERTY;
+    }
+
+    @Override
+    public void close() throws Exception { }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/FileInJarReadableDataSource.java

@@ -0,0 +1,126 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.util.AssertUtil;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+/**
+ * <p>
+ * A {@link ReadableDataSource} based on jar file. This class can only read file initially when it loads file.
+ * </p>
+ * <p>
+ * Limitations: Default read buffer size is 1 MB, while max allowed buffer size is 4MB.
+ * File size should not exceed the buffer size, or exception will be thrown. Default charset is UTF-8.
+ * </p>
+ *
+ * @author dingq
+ * @author Eric Zhao
+ * @since 1.6.0
+ */
+public class FileInJarReadableDataSource<T> extends AbstractDataSource<String, T> {
+
+    private static final int MAX_SIZE = 1024 * 1024 * 4;
+    private static final int DEFAULT_BUF_SIZE = 1024 * 1024;
+    private static final Charset DEFAULT_CHARSET = Charset.forName("utf-8");
+
+    private final Charset charset;
+    private final String jarName;
+    private final String fileInJarName;
+
+    private byte[] buf;
+    private JarEntry jarEntry;
+    private JarFile jarFile;
+
+    /**
+     * @param jarName       the jar to read
+     * @param fileInJarName the file in jar to read
+     * @param configParser  the config decoder (parser)
+     * @throws IOException if IO failure occurs
+     */
+    public FileInJarReadableDataSource(String jarName, String fileInJarName, Converter<String, T> configParser)
+        throws IOException {
+        this(jarName, fileInJarName, configParser, DEFAULT_BUF_SIZE, DEFAULT_CHARSET);
+    }
+
+    public FileInJarReadableDataSource(String jarName, String fileInJarName, Converter<String, T> configParser,
+                                       int bufSize) throws IOException {
+        this(jarName, fileInJarName, configParser, bufSize, DEFAULT_CHARSET);
+    }
+
+    public FileInJarReadableDataSource(String jarName, String fileInJarName, Converter<String, T> configParser,
+                                       Charset charset) throws IOException {
+        this(jarName, fileInJarName, configParser, DEFAULT_BUF_SIZE, charset);
+    }
+
+    public FileInJarReadableDataSource(String jarName, String fileInJarName, Converter<String, T> configParser,
+                                       int bufSize, Charset charset) throws IOException {
+        super(configParser);
+        AssertUtil.assertNotBlank(jarName, "jarName cannot be blank");
+        AssertUtil.assertNotBlank(fileInJarName, "fileInJarName cannot be blank");
+        if (bufSize <= 0 || bufSize > MAX_SIZE) {
+            throw new IllegalArgumentException("bufSize must between (0, " + MAX_SIZE + "], but " + bufSize + " get");
+        }
+        AssertUtil.notNull(charset, "charset can't be null");
+        this.buf = new byte[bufSize];
+        this.charset = charset;
+        this.jarName = jarName;
+        this.fileInJarName = fileInJarName;
+        initializeJar();
+        firstLoad();
+    }
+
+    @Override
+    public String readSource() throws Exception {
+        if (null == jarEntry) {
+            // Will throw FileNotFoundException later.
+            RecordLog.warn(String.format("[FileInJarReadableDataSource] File does not exist: %s", jarFile.getName()));
+        }
+        try (InputStream inputStream = jarFile.getInputStream(jarEntry)) {
+            if (inputStream.available() > buf.length) {
+                throw new IllegalStateException(String.format("Size of file <%s> exceeds the bufSize (%d): %d",
+                    jarFile.getName(), buf.length, inputStream.available()));
+            }
+            int len = inputStream.read(buf);
+            return new String(buf, 0, len, charset);
+        }
+    }
+
+    private void firstLoad() {
+        try {
+            T newValue = loadConfig();
+            getProperty().updateValue(newValue);
+        } catch (Throwable e) {
+            RecordLog.warn("[FileInJarReadableDataSource] Error when loading config", e);
+        }
+    }
+
+    @Override
+    public void close() throws Exception {
+        buf = null;
+    }
+
+    private void initializeJar() throws IOException {
+        this.jarFile = new JarFile(jarName);
+        this.jarEntry = jarFile.getJarEntry(fileInJarName);
+    }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/FileRefreshableDataSource.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.nio.channels.FileChannel;
+import java.nio.charset.Charset;
+
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+/**
+ * <p>
+ * A {@link ReadableDataSource} based on file. This class will automatically
+ * fetches the backend file every isModified period.
+ * </p>
+ * <p>
+ * Limitations: Default read buffer size is 1 MB. If file size is greater than
+ * buffer size, exceeding bytes will be ignored. Default charset is UTF-8.
+ * </p>
+ *
+ * @author Carpenter Lee
+ * @author Eric Zhao
+ */
+public class FileRefreshableDataSource<T> extends AutoRefreshDataSource<String, T> {
+
+    private static final int MAX_SIZE = 1024 * 1024 * 4;
+    private static final long DEFAULT_REFRESH_MS = 3000;
+    private static final int DEFAULT_BUF_SIZE = 1024 * 1024;
+    private static final Charset DEFAULT_CHAR_SET = Charset.forName("utf-8");
+
+    private byte[] buf;
+    private final Charset charset;
+    private final File file;
+
+    private long lastModified = 0L;
+
+    /**
+     * Create a file based {@link ReadableDataSource} whose read buffer size is
+     * 1MB, charset is UTF8, and read interval is 3 seconds.
+     *
+     * @param file         the file to read
+     * @param configParser the config decoder (parser)
+     */
+    public FileRefreshableDataSource(File file, Converter<String, T> configParser) throws FileNotFoundException {
+        this(file, configParser, DEFAULT_REFRESH_MS, DEFAULT_BUF_SIZE, DEFAULT_CHAR_SET);
+    }
+
+    public FileRefreshableDataSource(String fileName, Converter<String, T> configParser) throws FileNotFoundException {
+        this(new File(fileName), configParser, DEFAULT_REFRESH_MS, DEFAULT_BUF_SIZE, DEFAULT_CHAR_SET);
+    }
+
+    public FileRefreshableDataSource(File file, Converter<String, T> configParser, int bufSize)
+        throws FileNotFoundException {
+        this(file, configParser, DEFAULT_REFRESH_MS, bufSize, DEFAULT_CHAR_SET);
+    }
+
+    public FileRefreshableDataSource(File file, Converter<String, T> configParser, Charset charset)
+        throws FileNotFoundException {
+        this(file, configParser, DEFAULT_REFRESH_MS, DEFAULT_BUF_SIZE, charset);
+    }
+
+    public FileRefreshableDataSource(File file, Converter<String, T> configParser, long recommendRefreshMs, int bufSize,
+                                     Charset charset) throws FileNotFoundException {
+        super(configParser, recommendRefreshMs);
+        if (bufSize <= 0 || bufSize > MAX_SIZE) {
+            throw new IllegalArgumentException("bufSize must between (0, " + MAX_SIZE + "], but " + bufSize + " get");
+        }
+        if (file == null || file.isDirectory()) {
+            throw new IllegalArgumentException("File can't be null or a directory");
+        }
+        if (charset == null) {
+            throw new IllegalArgumentException("charset can't be null");
+        }
+        this.buf = new byte[bufSize];
+        this.file = file;
+        this.charset = charset;
+        // If the file does not exist, the last modified will be 0.
+        this.lastModified = file.lastModified();
+        firstLoad();
+    }
+
+    private void firstLoad() {
+        try {
+            T newValue = loadConfig();
+            getProperty().updateValue(newValue);
+        } catch (Throwable e) {
+            RecordLog.info("loadConfig exception", e);
+        }
+    }
+
+    @Override
+    public String readSource() throws Exception {
+        if (!file.exists()) {
+            // Will throw FileNotFoundException later.
+            RecordLog.warn(String.format("[FileRefreshableDataSource] File does not exist: %s", file.getAbsolutePath()));
+        }
+        FileInputStream inputStream = null;
+        try {
+            inputStream = new FileInputStream(file);
+            FileChannel channel = inputStream.getChannel();
+            if (channel.size() > buf.length) {
+                throw new IllegalStateException(file.getAbsolutePath() + " file size=" + channel.size()
+                    + ", is bigger than bufSize=" + buf.length + ". Can't read");
+            }
+            int len = inputStream.read(buf);
+            return new String(buf, 0, len, charset);
+        } finally {
+            if (inputStream != null) {
+                try {
+                    inputStream.close();
+                } catch (Exception ignore) {
+                }
+            }
+        }
+    }
+
+    @Override
+    protected boolean isModified() {
+        long curLastModified = file.lastModified();
+        if (curLastModified != this.lastModified) {
+            this.lastModified = curLastModified;
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public void close() throws Exception {
+        super.close();
+        buf = null;
+    }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/FileWritableDataSource.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.nio.charset.Charset;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+/**
+ * A {@link WritableDataSource} based on file.
+ *
+ * @param <T> data type
+ * @author Eric Zhao
+ * @since 0.2.0
+ */
+public class FileWritableDataSource<T> implements WritableDataSource<T> {
+
+    private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
+
+    private final Converter<T, String> configEncoder;
+    private final File file;
+    private final Charset charset;
+
+    private final Lock lock = new ReentrantLock(true);
+
+    public FileWritableDataSource(String filePath, Converter<T, String> configEncoder) {
+        this(new File(filePath), configEncoder);
+    }
+
+    public FileWritableDataSource(File file, Converter<T, String> configEncoder) {
+        this(file, configEncoder, DEFAULT_CHARSET);
+    }
+
+    public FileWritableDataSource(File file, Converter<T, String> configEncoder, Charset charset) {
+        if (file == null || file.isDirectory()) {
+            throw new IllegalArgumentException("Bad file");
+        }
+        if (configEncoder == null) {
+            throw new IllegalArgumentException("Config encoder cannot be null");
+        }
+        if (charset == null) {
+            throw new IllegalArgumentException("Charset cannot be null");
+        }
+        this.configEncoder = configEncoder;
+        this.file = file;
+        this.charset = charset;
+    }
+
+    @Override
+    public void write(T value) throws Exception {
+        lock.lock();
+        try {
+            String convertResult = configEncoder.convert(value);
+            FileOutputStream outputStream = null;
+            try {
+                outputStream = new FileOutputStream(file);
+                byte[] bytesArray = convertResult.getBytes(charset);
+
+                RecordLog.info("[FileWritableDataSource] Writing to file {}: {}", file, convertResult);
+                outputStream.write(bytesArray);
+                outputStream.flush();
+            } finally {
+                if (outputStream != null) {
+                    try {
+                        outputStream.close();
+                    } catch (Exception ignore) {
+                        // nothing
+                    }
+                }
+            }
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    @Override
+    public void close() throws Exception {
+        // Nothing
+    }
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/ReadableDataSource.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+import com.alibaba.csp.sentinel.property.SentinelProperty;
+
+/**
+ * The readable data source is responsible for retrieving configs (read-only).
+ *
+ * @param <S> source data type
+ * @param <T> target data type
+ * @author leyou
+ * @author Eric Zhao
+ */
+public interface ReadableDataSource<S, T> {
+
+    /**
+     * Load data data source as the target type.
+     *
+     * @return the target data.
+     * @throws Exception IO or other error occurs
+     */
+    T loadConfig() throws Exception;
+
+    /**
+     * Read original data from the data source.
+     *
+     * @return the original data.
+     * @throws Exception IO or other error occurs
+     */
+    S readSource() throws Exception;
+
+    /**
+     * Get {@link SentinelProperty} of the data source.
+     *
+     * @return the property.
+     */
+    SentinelProperty<T> getProperty();
+
+    /**
+     * Close the data source.
+     *
+     * @throws Exception IO or other error occurs
+     */
+    void close() throws Exception;
+}

sentinel/sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/WritableDataSource.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.datasource;
+
+/**
+ * Interface of writable data source support.
+ *
+ * @author Eric Zhao
+ * @since 0.2.0
+ */
+public interface WritableDataSource<T> {
+
+    /**
+     * Write the {@code value} to the data source.
+     *
+     * @param value value to write
+     * @throws Exception IO or other error occurs
+     */
+    void write(T value) throws Exception;
+
+    /**
+     * Close the data source.
+     *
+     * @throws Exception IO or other error occurs
+     */
+    void close() throws Exception;
+}