| /* |
| * Copyright (c) 1998, 2020 Oracle and/or its affiliates. All rights reserved. |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v. 2.0 which is available at |
| * http://www.eclipse.org/legal/epl-2.0, |
| * or the Eclipse Distribution License v. 1.0 which is available at |
| * http://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause |
| */ |
| |
| // Contributors: |
| // Oracle - initial API and implementation from Oracle TopLink |
| package org.eclipse.persistence.internal.sequencing; |
| |
| import java.util.*; |
| import java.util.concurrent.*; |
| |
| /** |
| * Handles the storage and allocation of sequence values. |
| * This is held by the session (ServerSession) through the SequencingManager. |
| * @see SequencingManager |
| */ |
| class PreallocationHandler implements SequencingLogInOut { |
| protected Map<String, Queue> preallocatedSequences; |
| |
| public PreallocationHandler() { |
| super(); |
| } |
| |
| /** |
| * Returns the Queue of sequences from the global sequences for the seqName. |
| * If there is not one, a new empty Queue is registered. |
| * This queue is thread-safe, and threads can concurrent poll the queue to remove the first element. |
| */ |
| public Queue getPreallocated(String sequenceName) { |
| Queue sequences = preallocatedSequences.get(sequenceName); |
| if (sequences == null) { |
| synchronized (preallocatedSequences) { |
| sequences = preallocatedSequences.get(sequenceName); |
| if (sequences == null) { |
| sequences = new ConcurrentLinkedQueue(); |
| preallocatedSequences.put(sequenceName, sequences); |
| } |
| } |
| } |
| return sequences; |
| } |
| |
| // SequencingLogInOut |
| @Override |
| public void onConnect() { |
| initializePreallocated(); |
| } |
| |
| @Override |
| public void onDisconnect() { |
| preallocatedSequences = null; |
| } |
| |
| @Override |
| public boolean isConnected() { |
| return preallocatedSequences != null; |
| } |
| |
| /** |
| * Removes all preallocated objects. |
| * A dangerous method to use in multithreaded environment method, |
| * but so handy for testing. |
| */ |
| public void initializePreallocated() { |
| preallocatedSequences = new ConcurrentHashMap(20); |
| } |
| |
| /** |
| * Removes all preallocated objects for the specified seqName. |
| * A dangerous method to use in multithreaded environment method, |
| * but so handy for testing. |
| */ |
| public void initializePreallocated(String seqName) { |
| preallocatedSequences.remove(seqName); |
| } |
| |
| /** |
| * Add the preallocated sequences to the global sequence pool for the sequence name. |
| * Although this method is thread-safe, a lock should typically be obtained from the sequence manager before calling this method, |
| * to ensure sequential numbers. |
| */ |
| public void setPreallocated(String seqName, Vector sequences) { |
| getPreallocated(seqName).addAll(sequences); |
| } |
| } |