001/*
002 * Copyright 2012-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.boot.actuate.audit;
018
019import java.time.Instant;
020import java.util.LinkedList;
021import java.util.List;
022
023import org.springframework.util.Assert;
024
025/**
026 * In-memory {@link AuditEventRepository} implementation.
027 *
028 * @author Dave Syer
029 * @author Phillip Webb
030 * @author Vedran Pavic
031 */
032public class InMemoryAuditEventRepository implements AuditEventRepository {
033
034        private static final int DEFAULT_CAPACITY = 1000;
035
036        private final Object monitor = new Object();
037
038        /**
039         * Circular buffer of the event with tail pointing to the last element.
040         */
041        private AuditEvent[] events;
042
043        private volatile int tail = -1;
044
045        public InMemoryAuditEventRepository() {
046                this(DEFAULT_CAPACITY);
047        }
048
049        public InMemoryAuditEventRepository(int capacity) {
050                this.events = new AuditEvent[capacity];
051        }
052
053        /**
054         * Set the capacity of this event repository.
055         * @param capacity the capacity
056         */
057        public void setCapacity(int capacity) {
058                synchronized (this.monitor) {
059                        this.events = new AuditEvent[capacity];
060                }
061        }
062
063        @Override
064        public void add(AuditEvent event) {
065                Assert.notNull(event, "AuditEvent must not be null");
066                synchronized (this.monitor) {
067                        this.tail = (this.tail + 1) % this.events.length;
068                        this.events[this.tail] = event;
069                }
070        }
071
072        @Override
073        public List<AuditEvent> find(String principal, Instant after, String type) {
074                LinkedList<AuditEvent> events = new LinkedList<>();
075                synchronized (this.monitor) {
076                        for (int i = 0; i < this.events.length; i++) {
077                                AuditEvent event = resolveTailEvent(i);
078                                if (event != null && isMatch(principal, after, type, event)) {
079                                        events.addFirst(event);
080                                }
081                        }
082                }
083                return events;
084        }
085
086        private boolean isMatch(String principal, Instant after, String type,
087                        AuditEvent event) {
088                boolean match = true;
089                match = match && (principal == null || event.getPrincipal().equals(principal));
090                match = match && (after == null || event.getTimestamp().isAfter(after));
091                match = match && (type == null || event.getType().equals(type));
092                return match;
093        }
094
095        private AuditEvent resolveTailEvent(int offset) {
096                int index = ((this.tail + this.events.length - offset) % this.events.length);
097                return this.events[index];
098        }
099
100}