[GitHub] [incubator-iceberg] waterlx commented on a change in pull request #653: Add CachingCatalog

[GitBox <gi...@apache.org>]

waterlx commented on a change in pull request #653: Add CachingCatalog
URL: https://github.com/apache/incubator-iceberg/pull/653#discussion_r368864075
 
 

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 File path: core/src/main/java/org/apache/iceberg/CachingCatalog.java
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+/*
+ * 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.iceberg;
+
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import org.apache.iceberg.catalog.Catalog;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.exceptions.AlreadyExistsException;
+
+public class CachingCatalog implements Catalog {
+
+  public static Catalog wrap(Catalog catalog) {
+    return new CachingCatalog(catalog);
+  }
+
+  private final Cache<TableIdentifier, Table> tableCache = Caffeine.newBuilder()
+      .softValues()
+      .expireAfterAccess(1, TimeUnit.MINUTES)
+      .build();
+  private final Catalog catalog;
+
+  private CachingCatalog(Catalog catalog) {
+    this.catalog = catalog;
+  }
+
+  @Override
+  public Table loadTable(TableIdentifier ident) {
+    return tableCache.get(ident, catalog::loadTable);
+  }
+
+  @Override
+  public Table createTable(TableIdentifier ident, Schema schema, PartitionSpec spec, String location,
+                           Map<String, String> properties) {
+    AtomicBoolean created = new AtomicBoolean(false);
+    Table table = tableCache.get(ident, identifier -> {
+      created.set(true);
+      return catalog.createTable(identifier, schema, spec, location, properties);
+    });
+
+    if (!created.get()) {
+      throw new AlreadyExistsException("Table already exists: %s", ident);
+    }
+
+    return table;
+  }
+
+  @Override
+  public Transaction newCreateTableTransaction(TableIdentifier ident, Schema schema, PartitionSpec spec,
+                                               String location, Map<String, String> properties) {
+    // create a new transaction without altering the cache. the table doesn't exist until the transaction is committed.
+    // if the table is created before the transaction commits, any cached version is correct and the transaction create
+    // will fail. if the transaction commits before another create, then the cache will be empty.
+    return catalog.newCreateTableTransaction(ident, schema, spec, location, properties);
+  }
+
+  @Override
+  public Transaction newReplaceTableTransaction(TableIdentifier ident, Schema schema, PartitionSpec spec,
+                                                String location, Map<String, String> properties, boolean orCreate) {
+    // create a new transaction without altering the cache. the table doesn't change until the transaction is committed.
+    // when the transaction commits, invalidate the table in the cache if it is present.
+    return CommitCallbackTransaction.addCallback(
+        catalog.newReplaceTableTransaction(ident, schema, spec, location, properties, orCreate),
+        () -> tableCache.invalidate(ident));
+  }
+
+  @Override
+  public boolean dropTable(TableIdentifier ident, boolean purge) {
+    boolean dropped = catalog.dropTable(ident, false);
 
 Review comment:
   Hi @rdblue could you please share your idea why purge is not passed further but dropTable with "false" instead?

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