zachjsh commented on code in PR #13165: URL: https://github.com/apache/druid/pull/13165#discussion_r1007255579
########## extensions-core/druid-catalog/src/main/java/org/apache/druid/catalog/storage/sql/CatalogManager.java: ########## @@ -0,0 +1,202 @@ +/* + * 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.druid.catalog.storage.sql; + +import org.apache.druid.catalog.model.TableId; +import org.apache.druid.catalog.model.TableMetadata; +import org.apache.druid.catalog.model.TableSpec; + +import javax.annotation.Nullable; + +import java.util.List; +import java.util.function.Function; + +/** + * Manages catalog data. Used in Coordinator, which will be in either + * an leader or standby state. The Coordinator calls the {@link #start()} + * method when it becomes the leader. + * + * Performs detailed CRUD operations on the catalog tables table. + * Higher-level operations appear elsewhere. + */ +public interface CatalogManager +{ + /** + * Thrown with an "optimistic lock" fails: the version of a + * catalog object being updated is not the same as that of + * the expected version. + */ + class OutOfDateException extends Exception + { + public OutOfDateException(String msg) + { + super(msg); + } + } + + /** + * Thrown when a record does not exist in the database. Allows + * the caller to check for this specific case in a generic way. + */ + class NotFoundException extends Exception + { + public NotFoundException(String msg) + { + super(msg); + } + } + + /** + * Indicates an attempt to insert a duplicate key into a table. + * This could indicate a logic error, or a race condition. It is + * generally not retryable: it us unrealistic to expect the other + * thread to helpfully delete the record it just added. + */ + class DuplicateKeyException extends Exception + { + public DuplicateKeyException(String msg, Exception e) + { + super(msg, e); + } + } + + /** + * Generic interface for changes to the catalog at the storage level. + * Implemented by the catalog sync mechanism to send update events + * to the Broker. Note that these events are about the <i>catalog</li>, + * not about the physical storage of tables (i.e. datasources.) + */ + interface Listener + { + /** + * A new catalog table entry was added. + */ + void added(TableMetadata table); + + /** + * An existing catalog table entry was updated. + */ + void updated(TableMetadata table); + + /** + * An existing catalog table entry was deleted. + */ + void deleted(TableId id); + } + + /** + * Start the catalog manager within a Druid run. Called from lifecycle + * management and when a coordinator becomes the leader node. + */ + void start(); + + /** + * Register a listener for catalog events. + */ + void register(Listener listener); + + /** + * Create a table entry. + * + * @return the version of the newly created table. Call + * {@link TableMetadata#asUpdate(long)} if you want a new + * {@link TableMetadata} with the new version. + * @throws {@link DuplicateKeyException} if the row is a duplicate + * (schema, name) pair. This generally indicates a code error, + * or since our code is perfect, a race condition or a DB + * update outside of Druid. In any event, the error is not + * retryable: the user should pick another name, or update the + * existing table + */ + long create(TableMetadata table) throws DuplicateKeyException; + + /** + * Update a table definition. + * <p> + * If {@code oldVersion == 0}, overwrites any current content. + * This is a potential race conditions if this is a partial update + * because of the possibility of another user doing an update since the + * read. Fine when the goal is to replace the entire definition. + * Else, only does the update is at the given version. + * <p> + * Retryable only if the version is given, and an + * {@code OutOfDateException} is thrown. + */ + long update(TableMetadata table, long oldVersion) throws OutOfDateException, NotFoundException; + + /** + * Update the table spec incrementally using the transform provided. Performs the update + * in a transaction to ensure the read and write are atomic. + * + * @param id the table to update + * @param transform the transform to apply to the table spec + * @return the update timestamp (version) of the updated record + */ + long updatePayload(TableId id, Function<TableSpec, TableSpec> transform) throws NotFoundException; + + /** + * Move the table to the deleting state. No version check: fine + * if the table is already in the deleting state. Does nothing if the + * table does not exist. + * + * @return new table update timestamp, or 0 if the table does not + * exist + */ + long markDeleting(TableId id); + + /** + * Read the table record for the given ID. + * + * @return the table record, or {@code null} if the entry is not + * found in the DB. + */ + @Nullable TableMetadata read(TableId id); + + /** + * Delete the table record for the given ID. Essentially does a + * "DELETE IF EXISTS". There is no version check. Delete should be + * called only when there are no segments left for the table: use + * {@link #markDeleting(TableId)} to indicates that the segments are + * being deleted. Call this method after deletion is complete. + * <p> + * Does not cascade deletes yet. Eventually, should delete all entries + * for the table. + * + * @return {@code true} if the table exists and was deleted, + * {@code false} if the table did not exist. + */ + boolean delete(TableId id); + + /** + * Returns a list of the ids (schema, name) of all tables in the catalog. + */ + List<TableId> list(); Review Comment: nit: think `listIds` would be more clear. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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