SPARK-24252: Add v2 data source mix-in for catalog support.

sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/CaseInsensitiveStringMap.java

@@ -0,0 +1,107 @@
+/*
+ * 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.spark.sql.catalog.v2;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Case-insensitive map of string keys to string values.
+ * <p>
+ * This is used to pass options to v2 implementations to ensure consistent case insensitivity.
+ * <p>
+ * Methods that return keys in this map, like {@link #entrySet()} and {@link #keySet()}, return
+ * keys converted to lower case.
+ */
+public class CaseInsensitiveStringMap implements Map<String, String> {
+
+  public static CaseInsensitiveStringMap empty() {
+    return new CaseInsensitiveStringMap();
+  }
+
+  private final Map<String, String> delegate;
+
+  private CaseInsensitiveStringMap() {
+    this.delegate = new HashMap<>();
+  }
+
+  @Override
+  public int size() {
+    return delegate.size();
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return delegate.isEmpty();
+  }
+
+  @Override
+  public boolean containsKey(Object key) {
+    return delegate.containsKey(key.toString().toLowerCase(Locale.ROOT));
+  }
+
+  @Override
+  public boolean containsValue(Object value) {
+    return delegate.containsValue(value);
+  }
+
+  @Override
+  public String get(Object key) {
+    return delegate.get(key.toString().toLowerCase(Locale.ROOT));
+  }
+
+  @Override
+  public String put(String key, String value) {
+    return delegate.put(key.toLowerCase(Locale.ROOT), value);
+  }
+
+  @Override
+  public String remove(Object key) {
+    return delegate.remove(key.toString().toLowerCase(Locale.ROOT));
+  }
+
+  @Override
+  public void putAll(Map<? extends String, ? extends String> m) {
+    for (Map.Entry<? extends String, ? extends String> entry : m.entrySet()) {
+      delegate.put(entry.getKey().toLowerCase(Locale.ROOT), entry.getValue());
+    }
+  }
+
+  @Override
+  public void clear() {
+    delegate.clear();
+  }
+
+  @Override
+  public Set<String> keySet() {
+    return delegate.keySet();
+  }
+
+  @Override
+  public Collection<String> values() {
+    return delegate.values();
+  }
+
+  @Override
+  public Set<Map.Entry<String, String>> entrySet() {
+    return delegate.entrySet();
+  }
+}

sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/CatalogProvider.java

@@ -0,0 +1,50 @@
+/*
+ * 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.spark.sql.catalog.v2;
+
+import org.apache.spark.sql.internal.SQLConf;
+
+/**
+ * A marker interface to provide a catalog implementation for Spark.
+ * <p>
+ * Implementations can provide catalog functions by implementing additional interfaces, like
+ * {@link TableCatalog} to expose table operations.
+ * <p>
+ * Catalog implementations must implement this marker interface to be loaded by
+ * {@link Catalogs#load(String, SQLConf)}. The loader will instantiate catalog classes using the
+ * required public no-arg constructor. After creating an instance, it will be configured by calling
+ * {@link #initialize(CaseInsensitiveStringMap)}.
+ * <p>
+ * Catalog implementations are registered to a name by adding a configuration option to Spark:
+ * {@code spark.sql.catalog.catalog-name=com.example.YourCatalogClass}. All configuration properties
+ * in the Spark configuration that share the catalog name prefix,
+ * {@code spark.sql.catalog.catalog-name.(key)=(value)} will be passed in the case insensitive
+ * string map of options in initialization with the prefix removed. An additional property,
+ * {@code name}, is also added to the options and will contain the catalog's name; in this case,
+ * "catalog-name".
+ */
+public interface CatalogProvider {
+  /**
+   * Called to initialize configuration.
+   * <p>
+   * This method is called once, just after the provider is instantiated.
+   *
+   * @param options a case-insensitive string map of configuration
+   */
+  void initialize(CaseInsensitiveStringMap options);
+}

sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/Catalogs.java

@@ -0,0 +1,109 @@
+/*
+ * 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.spark.sql.catalog.v2;
+
+import org.apache.spark.SparkException;
+import org.apache.spark.sql.internal.SQLConf;
+import org.apache.spark.util.Utils;
+
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static scala.collection.JavaConverters.mapAsJavaMapConverter;
+
+public class Catalogs {
+  private Catalogs() {
+  }
+
+  /**
+   * Load and configure a catalog by name.
+   * <p>
+   * This loads, instantiates, and initializes the catalog provider for each call; it does not
+   * cache or reuse instances.
+   *
+   * @param name a String catalog name
+   * @param conf a SQLConf
+   * @return an initialized CatalogProvider
+   * @throws SparkException If the provider class cannot be found or instantiated
+   */
+  public static CatalogProvider load(String name, SQLConf conf) throws SparkException {
+    String providerClassName = conf.getConfString("spark.sql.catalog." + name, null);
+    if (providerClassName == null) {
+      throw new SparkException(String.format(
+          "Catalog '%s' provider not found: spark.sql.catalog.%s is not defined", name, name));
+    }
+
+    ClassLoader loader = Utils.getContextOrSparkClassLoader();
+
+    try {
+      Class<?> providerClass = loader.loadClass(providerClassName);
+
+      if (!CatalogProvider.class.isAssignableFrom(providerClass)) {
+        throw new SparkException(String.format(
+            "Provider class for catalog '%s' does not implement CatalogProvider: %s",
+            name, providerClassName));
+      }
+
+      CatalogProvider provider = CatalogProvider.class.cast(providerClass.newInstance());
+
+      provider.initialize(catalogOptions(name, conf));
+
+      return provider;
+
+    } catch (ClassNotFoundException e) {
+      throw new SparkException(String.format(
+          "Cannot find catalog provider class for catalog '%s': %s", name, providerClassName));
+
+    } catch (IllegalAccessException e) {
+      throw new SparkException(String.format(
+          "Failed to call public no-arg constructor for catalog '%s': %s", name, providerClassName),
+          e);
+
+    } catch (InstantiationException e) {
+      throw new SparkException(String.format(
+          "Failed while instantiating provider for catalog '%s': %s", name, providerClassName),
+          e.getCause());
+    }
+  }
+
+  /**
+   * Extracts a named catalog's configuration from a SQLConf.
+   *
+   * @param name a catalog name
+   * @param conf a SQLConf
+   * @return a case insensitive string map of options starting with spark.sql.catalog.(name).
+   */
+  private static CaseInsensitiveStringMap catalogOptions(String name, SQLConf conf) {
+    Map<String, String> allConfs = mapAsJavaMapConverter(conf.getAllConfs()).asJava();
+    Pattern prefix = Pattern.compile("^spark\\.sql\\.catalog\\." + name + "\\.(.+)");
+
+    CaseInsensitiveStringMap options = CaseInsensitiveStringMap.empty();
+    for (Map.Entry<String, String> entry : allConfs.entrySet()) {
+      Matcher matcher = prefix.matcher(entry.getKey());
+      if (matcher.matches() && matcher.groupCount() > 0) {
+        options.put(matcher.group(1), entry.getValue());
+      }
+    }
+
+    // add name last to ensure it overwrites any conflicting options
+    options.put("name", name);
+
+    return options;
+  }
+}

sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/Table.java

@@ -0,0 +1,47 @@
+/*
+ * 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.spark.sql.catalog.v2;
+
+import org.apache.spark.sql.catalyst.expressions.Expression;
+import org.apache.spark.sql.types.StructType;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Represents table metadata from a {@link TableCatalog} or other table sources.
+ */
+public interface Table {
+  /**
+   * Return the table properties.
+   * @return this table's map of string properties
+   */
+  Map<String, String> properties();
+
+  /**
+   * Return the table schema.
+   * @return this table's schema as a struct type
+   */
+  StructType schema();
+
+  /**
+   * Return the table partitioning expressions.
+   * @return this table's partitioning expressions
+   */
+  List<Expression> partitionExpressions();
+}