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https://issues.apache.org/jira/browse/FLINK-3035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15140934#comment-15140934
]
ASF GitHub Bot commented on FLINK-3035:
---------------------------------------
Github user mjsax commented on a diff in the pull request:
https://github.com/apache/flink/pull/1617#discussion_r52468108
--- Diff:
flink-contrib/flink-statebackend-redis/src/main/java/org/apache/flink/contrib/streaming/state/AbstractRedisState.java
---
@@ -0,0 +1,374 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.flink.contrib.streaming.state;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.IOUtils;
+import org.apache.flink.api.common.state.State;
+import org.apache.flink.api.common.state.StateDescriptor;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.core.memory.DataOutputView;
+import org.apache.flink.core.memory.DataOutputViewStreamWrapper;
+import org.apache.flink.runtime.state.AbstractStateBackend;
+import org.apache.flink.runtime.state.KvState;
+import org.apache.flink.runtime.state.KvStateSnapshot;
+import org.apache.flink.util.HDFSCopyFromLocal;
+import org.apache.flink.util.HDFSCopyToLocal;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import redis.clients.jedis.BinaryJedis;
+import redis.clients.jedis.exceptions.JedisConnectionException;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URI;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Base class for {@link State} implementations that store state in a
Redis database.
+ *
+ * <p>This base class is responsible for setting up the Redis database, for
+ * checkpointing/restoring the database and for disposal in the {@link
#dispose()} method. The
+ * concrete subclasses just use the Redis handle to store/retrieve state.
+ *
+ * @param <K> The type of the key.
+ * @param <N> The type of the namespace.
+ * @param <S> The type of {@link State}.
+ * @param <SD> The type of {@link StateDescriptor}.
+ * @param <Backend> The type of the backend that snapshots this key/value
state.
+ */
+public abstract class AbstractRedisState<K, N, S extends State, SD extends
StateDescriptor<S, ?>, Backend extends AbstractStateBackend>
+ implements KvState<K, N, S, SD, Backend>, State {
+
+ /** Serializer for the keys */
+ protected final TypeSerializer<K> keySerializer;
+
+ /** Serializer for the namespace */
+ protected final TypeSerializer<N> namespaceSerializer;
+
+ /** The current key, which the next value methods will refer to */
+ protected K currentKey;
+
+ /** The current namespace, which the next value methods will refer to */
+ protected N currentNamespace;
+
+ /** Store it so that we can clean up in dispose() */
+ protected final File dbPath;
+
+ protected final String checkpointPath;
+
+ /** Our Redis instance */
+ protected Process redisServerProcess;
+ protected final BinaryJedis db;
+
+ /**
+ * Creates a new Redis backed state.
+ *
+ * @param redisExecPath The path on the local system where Redis
executable file can be found.
+ * @param port The port to start Redis server
+ * @param keySerializer The serializer for the keys.
+ * @param namespaceSerializer The serializer for the namespace.
+ * @param dbPath The path on the local system where Redis data should
be stored.
+ */
+ protected AbstractRedisState(String redisExecPath, int port,
TypeSerializer<K> keySerializer, TypeSerializer<N> namespaceSerializer, File
dbPath, String checkpointPath) {
+ this.keySerializer = keySerializer;
+ this.namespaceSerializer = namespaceSerializer;
+ this.dbPath = dbPath;
+ this.checkpointPath = checkpointPath;
+
+ if (!dbPath.exists()) {
+ if (!dbPath.mkdirs()) {
+ throw new RuntimeException("Could not create
Redis data directory.");
+ }
+ }
+
+ try {
+ startRedisServer(redisExecPath, "--port",
String.valueOf(port), "--dir", dbPath.getAbsolutePath());
+ } catch (IOException e) {
+ throw new RuntimeException("Could not start Redis
server", e);
+ }
+
+ try {
+ db = new BinaryJedis("localhost", port);
+ db.ping();
+ } catch (JedisConnectionException e) {
+ throw new RuntimeException("Error while opening
connection to Redis server", e);
+ }
+ }
+
+ /**
+ * Creates a new Redis backed state and restores from the given backup
directory. After
+ * restoring the backup directory is deleted.
+ *
+ * @param redisExecPath The path on the local system where Redis
executable file can be found.
+ * @param port The port to start Redis server
+ * @param keySerializer The serializer for the keys.
+ * @param namespaceSerializer The serializer for the namespace.
+ * @param dbPath The path on the local system where RocksDB data should
be stored.
+ * @param restorePath The path to a backup directory from which to
restore Redis database.
+ */
+ protected AbstractRedisState(String redisExecPath, int port,
TypeSerializer<K> keySerializer, TypeSerializer<N> namespaceSerializer, File
dbPath, String checkpointPath, String restorePath) {
+ try {
+ HDFSCopyToLocal.copyToLocal(new URI(restorePath +
"/dump.rdb"), dbPath);
+ } catch (Exception e) {
+ throw new RuntimeException("Error while restoring Redis
state from " + restorePath, e);
+ }
+
+ try {
+ startRedisServer(redisExecPath, "--port",
String.valueOf(port), "--dir", dbPath.getAbsolutePath());
+ } catch (IOException e) {
+ throw new RuntimeException("Could not start Redis
server");
+ }
+
+ this.keySerializer = keySerializer;
+ this.namespaceSerializer = namespaceSerializer;
+ this.dbPath = dbPath;
+ this.checkpointPath = checkpointPath;
+
+ if (!dbPath.exists()) {
+ if (!dbPath.mkdirs()) {
+ throw new RuntimeException("Could not create
Redis data directory.");
+ }
+ }
+
+ try {
+ db = new BinaryJedis("localhost", port);
+ db.ping();
+ } catch (JedisConnectionException e) {
+ throw new RuntimeException("Error while opening
connection to Redis server", e);
+ }
+ }
+
+ //
------------------------------------------------------------------------
+
+ @Override
+ final public void clear() {
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ DataOutputViewStreamWrapper out = new
DataOutputViewStreamWrapper(baos);
+ try {
+ writeKeyAndNamespace(out);
+ byte[] key = baos.toByteArray();
+ db.del(key);
+ } catch (IOException e) {
+ throw new RuntimeException("Error while removing entry
from Redis", e);
+ }
+ }
+
+ protected void writeKeyAndNamespace(DataOutputView out) throws
IOException {
+ keySerializer.serialize(currentKey, out);
+ out.writeByte(42);
+ namespaceSerializer.serialize(currentNamespace, out);
+ }
+
+ @Override
+ public void setCurrentKey(K currentKey) {
+ this.currentKey = currentKey;
+ }
+
+ @Override
+ public void setCurrentNamespace(N currentNamespace) {
+ this.currentNamespace = currentNamespace;
+ }
+
+ protected abstract KvStateSnapshot<K, N, S, SD, Backend>
createRedisSnapshot(URI backupUri, long checkpointId);
+
+ @Override
+ public KvStateSnapshot<K, N, S, SD, Backend> snapshot(long
checkpointId, long timestamp) throws Exception {
+ boolean success = false;
+
+ final File localBackupPath = new File(dbPath, "backup-" +
checkpointId);
+ final URI backupUri = new URI(checkpointPath + "/chk-" +
checkpointId);
+
+ try {
+ if (!localBackupPath.exists()) {
+ if (!localBackupPath.mkdirs()) {
+ throw new RuntimeException("Could not
create local backup path " + localBackupPath);
+ }
+ }
+
+ db.configSet("dir".getBytes(),
localBackupPath.getAbsolutePath().getBytes());
+ db.save();
+
+ HDFSCopyFromLocal.copyFromLocal(localBackupPath,
backupUri);
+ KvStateSnapshot<K, N, S, SD, Backend> result =
createRedisSnapshot(backupUri, checkpointId);
+ success = true;
+ return result;
+ }finally {
+ FileUtils.deleteDirectory(localBackupPath);
+ if (!success) {
+ FileSystem fs = FileSystem.get(backupUri, new
Configuration());
+ fs.delete(new Path(backupUri), true);
+ }
+ }
+ }
+
+ @Override
+ public void dispose() {
+ db.disconnect();
+ stopRedisServer();
+ try {
+ FileUtils.deleteDirectory(dbPath);
+ } catch (IOException e) {
+ throw new RuntimeException("Error disposing Redis data
directory.", e);
+ }
+ }
+
+ /**
+ * Starts the Redis server
+ *
+ * @param args
+ * @throws IOException
+ */
+ private synchronized void startRedisServer(String... args) throws
IOException {
+ List<String> argsList = Arrays.asList(args);
+ File executable = new File(argsList.get(0));
+ ProcessBuilder pb = new ProcessBuilder(argsList);
+ pb.directory(executable.getParentFile());
+
+ redisServerProcess = pb.start();
+
+ BufferedReader reader = new BufferedReader(new
InputStreamReader(redisServerProcess.getInputStream()));
+ try {
+ String outputLine;
+ do {
+ outputLine = reader.readLine();
+ if (outputLine == null) {
+ //Something goes wrong. Stream is ended
before server was activated.
+ throw new RuntimeException("Can't start
redis server. Check logs for details.");
+ }
+ } while (!outputLine.matches(".*The server is now ready
to accept connections on port.*"));
--- End diff --
Is there a better way to check this condition?
> Redis as State Backend
> ----------------------
>
> Key: FLINK-3035
> URL: https://issues.apache.org/jira/browse/FLINK-3035
> Project: Flink
> Issue Type: New Feature
> Components: Streaming
> Reporter: Matthias J. Sax
> Assignee: Subhobrata Dey
> Priority: Minor
>
> Add Redis as a state backend for distributed snapshots.
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