[GitHub] [incubator-gobblin] jack-moseley commented on a change in pull request #2631: [GOBBLIN-768] Add MySQL implementation of SpecStore

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jack-moseley commented on a change in pull request #2631: [GOBBLIN-768] Add MySQL implementation of SpecStore
URL: https://github.com/apache/incubator-gobblin/pull/2631#discussion_r283487436
 
 

 ##########
 File path: gobblin-runtime/src/main/java/org/apache/gobblin/runtime/spec_store/MysqlSpecStore.java
 ##########
 @@ -0,0 +1,215 @@
+/*
+ * 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.gobblin.runtime.spec_store;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.net.URI;
+import java.sql.Blob;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.Lists;
+import com.typesafe.config.Config;
+
+import javax.sql.DataSource;
+
+import org.apache.gobblin.broker.SharedResourcesBrokerFactory;
+import org.apache.gobblin.configuration.ConfigurationKeys;
+import org.apache.gobblin.metastore.MysqlDataSourceFactory;
+import org.apache.gobblin.runtime.api.Spec;
+import org.apache.gobblin.runtime.api.SpecNotFoundException;
+import org.apache.gobblin.runtime.api.SpecStore;
+
+
+/**
+ * Implementation of {@link SpecStore} that stores specs as serialized java objects in MySQL. Note that versions are not
+ * supported, so the version parameter will be ignored in methods that have it.
+ */
+public class MysqlSpecStore implements SpecStore {
+  private static final String CREATE_TABLE_STATEMENT =
+      "CREATE TABLE IF NOT EXISTS %s (spec_uri VARCHAR(128) NOT NULL, spec LONGBLOB, PRIMARY KEY (spec_uri))";
+  private static final String EXISTS_STATEMENT = "SELECT EXISTS(SELECT * FROM %s WHERE spec_uri = ?)";
+  private static final String INSERT_STATEMENT = "INSERT INTO %s (spec_uri, spec) VALUES (?, ?) ON DUPLICATE KEY UPDATE spec = VALUES(spec)";
+  private static final String DELETE_STATEMENT = "DELETE FROM %s WHERE spec_uri = ?";
+  private static final String GET_STATEMENT = "SELECT spec FROM %s WHERE spec_uri = ?";
+  private static final String GET_ALL_STATEMENT = "SELECT spec_uri, spec FROM %s";
+
+  private DataSource dataSource;
+  private String tableName;
+  private URI specStoreURI;
+
+  public MysqlSpecStore(Config config) throws IOException {
+    this.dataSource = MysqlDataSourceFactory.get(config, SharedResourcesBrokerFactory.getImplicitBroker());
+    this.tableName = config.getString(ConfigurationKeys.STATE_STORE_DB_TABLE_KEY);
+    this.specStoreURI = URI.create(config.getString(ConfigurationKeys.STATE_STORE_DB_URL_KEY));
+    try (Connection connection = this.dataSource.getConnection();
+        PreparedStatement statement = connection.prepareStatement(String.format(CREATE_TABLE_STATEMENT, this.tableName))) {
+      statement.executeUpdate();
+    } catch (SQLException e) {
+      throw new IOException(e);
+    }
+  }
+
+  @Override
+  public boolean exists(URI specUri) throws IOException {
+    try (Connection connection = this.dataSource.getConnection();
+        PreparedStatement statement = connection.prepareStatement(String.format(EXISTS_STATEMENT, this.tableName))) {
+      statement.setString(1, specUri.toString());
+      ResultSet rs = statement.executeQuery();
+      rs.next();
+      return rs.getBoolean(1);
+    } catch (SQLException e) {
+      throw new IOException(e);
+    }
+  }
+
+  @Override
+  public void addSpec(Spec spec) throws IOException {
+    try (Connection connection = this.dataSource.getConnection();
+        PreparedStatement statement = connection.prepareStatement(String.format(INSERT_STATEMENT, this.tableName));
+        ByteArrayOutputStream aos = new ByteArrayOutputStream();
+        ObjectOutputStream oos = new ObjectOutputStream(aos)) {
+
+      oos.writeObject(spec);
 
 Review comment:
   I think @jhsenjaliya is correct though, it's probably better to pass a `SpecSerDe` in the constructor and use it for serializing the same way it's done in `FSSpecStore`.

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