| // 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 |
| // 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 com.cloud.utils.db; |
| |
| import java.sql.PreparedStatement; |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| import java.util.Random; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.ThreadPoolExecutor; |
| import java.util.concurrent.TimeUnit; |
| |
| import javax.persistence.TableGenerator; |
| |
| import org.apache.log4j.Logger; |
| |
| import com.cloud.utils.concurrency.NamedThreadFactory; |
| |
| /** |
| * Since Mysql does not have sequence support, we have |
| * table retrieval was inside a transaction, the value |
| * gets locked until the transaction is over. |
| * |
| * allocation size. |
| * |
| */ |
| public class SequenceFetcher { |
| private final static Logger s_logger = Logger.getLogger(SequenceFetcher.class); |
| ExecutorService _executors; |
| private final static Random random = new Random(); |
| |
| public <T> T getNextSequence(Class<T> clazz, TableGenerator tg) { |
| return getNextSequence(clazz, tg, null, false); |
| } |
| |
| public <T> T getNextSequence(Class<T> clazz, TableGenerator tg, Object key) { |
| return getNextSequence(clazz, tg, key, false); |
| } |
| |
| public <T> T getRandomNextSequence(Class<T> clazz, TableGenerator tg) { |
| return getNextSequence(clazz, tg, null, true); |
| } |
| |
| public <T> T getNextSequence(Class<T> clazz, TableGenerator tg, Object key, boolean isRandom) { |
| Future<T> future = _executors.submit(new Fetcher<T>(clazz, tg, key, isRandom)); |
| try { |
| return future.get(); |
| } catch (Exception e) { |
| s_logger.warn("Unable to get sequeunce for " + tg.table() + ":" + tg.pkColumnValue(), e); |
| return null; |
| } |
| } |
| |
| protected SequenceFetcher() { |
| _executors = new ThreadPoolExecutor(100, 100, 120l, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(250), new NamedThreadFactory("SequenceFetcher")); |
| } |
| |
| protected static final SequenceFetcher s_instance = new SequenceFetcher(); |
| |
| public static SequenceFetcher getInstance() { |
| return s_instance; |
| } |
| |
| protected class Fetcher<T> implements Callable<T> { |
| TableGenerator _tg; |
| Class<T> _clazz; |
| Object _key; |
| boolean isRandom = false; |
| |
| protected Fetcher(Class<T> clazz, TableGenerator tg, Object key, boolean isRandom) { |
| _tg = tg; |
| _clazz = clazz; |
| _key = key; |
| this.isRandom = isRandom; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public T call() throws Exception { |
| StringBuilder sql = new StringBuilder("SELECT "); |
| sql.append(_tg.valueColumnName()).append(" FROM ").append(_tg.table()); |
| sql.append(" WHERE ").append(_tg.pkColumnName()).append(" = ? FOR UPDATE"); |
| |
| |
| try (TransactionLegacy txn = TransactionLegacy.open("Sequence"); |
| PreparedStatement selectStmt = txn.prepareStatement(sql.toString()); |
| ) { |
| if (_key == null) { |
| selectStmt.setString(1, _tg.pkColumnValue()); |
| } else { |
| selectStmt.setObject(1, _key); |
| } |
| |
| sql = new StringBuilder("UPDATE "); |
| sql.append(_tg.table()).append(" SET ").append(_tg.valueColumnName()).append("=").append("?+?"); |
| sql.append(" WHERE ").append(_tg.pkColumnName()).append("=?"); |
| |
| try (PreparedStatement updateStmt = txn.prepareStatement(sql.toString());) { |
| if (isRandom) { |
| updateStmt.setInt(2, random.nextInt(10) + 1); |
| } else { |
| updateStmt.setInt(2, _tg.allocationSize()); |
| } |
| if (_key == null) { |
| updateStmt.setString(3, _tg.pkColumnValue()); |
| } else { |
| updateStmt.setObject(3, _key); |
| } |
| |
| txn.start(); |
| Object obj = null; |
| try (ResultSet rs = selectStmt.executeQuery();) { |
| |
| while (rs.next()) { |
| if (_clazz.isAssignableFrom(Long.class)) { |
| obj = rs.getLong(1); |
| } else if (_clazz.isAssignableFrom(Integer.class)) { |
| obj = rs.getInt(1); |
| } else { |
| obj = rs.getObject(1); |
| } |
| } |
| } catch (SQLException e) { |
| s_logger.warn("Caught this exception when running: " + (selectStmt != null ? selectStmt.toString() : ""), e); |
| } |
| |
| if (obj == null) { |
| s_logger.warn("Unable to get a sequence: " + updateStmt.toString()); |
| return null; |
| } |
| |
| updateStmt.setObject(1, obj); |
| try { |
| int rows = updateStmt.executeUpdate(); |
| assert rows == 1 : "Come on....how exactly did we update this many rows " + rows + " for " + updateStmt.toString(); |
| txn.commit(); |
| return (T)obj; |
| } catch (SQLException e) { |
| s_logger.warn("Caught this exception when running: " + (updateStmt != null ? updateStmt.toString() : ""), e); |
| } |
| } |
| } |
| return null; |
| } |
| } |
| } |