| /* |
| * 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.cassandra.db; |
| |
| import org.apache.cassandra.config.CFMetaData; |
| import org.apache.cassandra.index.Index; |
| import org.apache.cassandra.utils.concurrent.OpOrder; |
| |
| public class ReadExecutionController implements AutoCloseable |
| { |
| // For every reads |
| private final OpOrder.Group baseOp; |
| private final CFMetaData baseMetadata; // kept to sanity check that we have take the op order on the right table |
| |
| // For index reads |
| private final ReadExecutionController indexController; |
| private final OpOrder.Group writeOp; |
| |
| private ReadExecutionController(OpOrder.Group baseOp, CFMetaData baseMetadata, ReadExecutionController indexController, OpOrder.Group writeOp) |
| { |
| // We can have baseOp == null, but only when empty() is called, in which case the controller will never really be used |
| // (which validForReadOn should ensure). But if it's not null, we should have the proper metadata too. |
| assert (baseOp == null) == (baseMetadata == null); |
| this.baseOp = baseOp; |
| this.baseMetadata = baseMetadata; |
| this.indexController = indexController; |
| this.writeOp = writeOp; |
| } |
| |
| public ReadExecutionController indexReadController() |
| { |
| return indexController; |
| } |
| |
| public OpOrder.Group writeOpOrderGroup() |
| { |
| return writeOp; |
| } |
| |
| public boolean validForReadOn(ColumnFamilyStore cfs) |
| { |
| return baseOp != null && cfs.metadata.cfId.equals(baseMetadata.cfId); |
| } |
| |
| public static ReadExecutionController empty() |
| { |
| return new ReadExecutionController(null, null, null, null); |
| } |
| |
| /** |
| * Creates an execution controller for the provided command. |
| * <p> |
| * Note: no code should use this method outside of {@link ReadCommand#executionController} (for |
| * consistency sake) and you should use that latter method if you need an execution controller. |
| * |
| * @param command the command for which to create a controller. |
| * @return the created execution controller, which must always be closed. |
| */ |
| @SuppressWarnings("resource") // ops closed during controller close |
| static ReadExecutionController forCommand(ReadCommand command) |
| { |
| ColumnFamilyStore baseCfs = Keyspace.openAndGetStore(command.metadata()); |
| ColumnFamilyStore indexCfs = maybeGetIndexCfs(baseCfs, command); |
| |
| if (indexCfs == null) |
| { |
| return new ReadExecutionController(baseCfs.readOrdering.start(), baseCfs.metadata, null, null); |
| } |
| else |
| { |
| OpOrder.Group baseOp = null, writeOp = null; |
| ReadExecutionController indexController = null; |
| // OpOrder.start() shouldn't fail, but better safe than sorry. |
| try |
| { |
| baseOp = baseCfs.readOrdering.start(); |
| indexController = new ReadExecutionController(indexCfs.readOrdering.start(), indexCfs.metadata, null, null); |
| // TODO: this should perhaps not open and maintain a writeOp for the full duration, but instead only *try* to delete stale entries, without blocking if there's no room |
| // as it stands, we open a writeOp and keep it open for the duration to ensure that should this CF get flushed to make room we don't block the reclamation of any room being made |
| writeOp = Keyspace.writeOrder.start(); |
| return new ReadExecutionController(baseOp, baseCfs.metadata, indexController, writeOp); |
| } |
| catch (RuntimeException e) |
| { |
| // Note that must have writeOp == null since ReadOrderGroup ctor can't fail |
| assert writeOp == null; |
| try |
| { |
| if (baseOp != null) |
| baseOp.close(); |
| } |
| finally |
| { |
| if (indexController != null) |
| indexController.close(); |
| } |
| throw e; |
| } |
| } |
| } |
| |
| private static ColumnFamilyStore maybeGetIndexCfs(ColumnFamilyStore baseCfs, ReadCommand command) |
| { |
| Index index = command.getIndex(baseCfs); |
| return index == null ? null : index.getBackingTable().orElse(null); |
| } |
| |
| public CFMetaData metaData() |
| { |
| return baseMetadata; |
| } |
| |
| public void close() |
| { |
| try |
| { |
| if (baseOp != null) |
| baseOp.close(); |
| } |
| finally |
| { |
| if (indexController != null) |
| { |
| try |
| { |
| indexController.close(); |
| } |
| finally |
| { |
| writeOp.close(); |
| } |
| } |
| } |
| } |
| } |