001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.activemq.usage;
018    
019    /**
020     * Used to keep track of how much of something is being used so that a
021     * productive working set usage can be controlled. Main use case is manage
022     * memory usage.
023     * 
024     * @org.apache.xbean.XBean
025     * 
026     */
027    public class MemoryUsage extends Usage<MemoryUsage> {
028    
029        private long usage;
030    
031        public MemoryUsage() {
032            this(null, null);
033        }
034    
035        /**
036         * Create the memory manager linked to a parent. When the memory manager is
037         * linked to a parent then when usage increased or decreased, the parent's
038         * usage is also increased or decreased.
039         * 
040         * @param parent
041         */
042        public MemoryUsage(MemoryUsage parent) {
043            this(parent, "default");
044        }
045    
046        public MemoryUsage(String name) {
047            this(null, name);
048        }
049    
050        public MemoryUsage(MemoryUsage parent, String name) {
051            this(parent, name, 1.0f);
052        }
053    
054        public MemoryUsage(MemoryUsage parent, String name, float portion) {
055            super(parent, name, portion);
056        }
057    
058        /**
059         * @throws InterruptedException
060         */
061        public void waitForSpace() throws InterruptedException {
062            if (parent != null) {
063                parent.waitForSpace();
064            }
065            synchronized (usageMutex) {
066                for (int i = 0; percentUsage >= 100; i++) {
067                    usageMutex.wait();
068                }
069            }
070        }
071    
072        /**
073         * @param timeout
074         * @throws InterruptedException
075         * @return true if space
076         */
077        public boolean waitForSpace(long timeout) throws InterruptedException {
078            if (parent != null) {
079                if (!parent.waitForSpace(timeout)) {
080                    return false;
081                }
082            }
083            synchronized (usageMutex) {
084                if (percentUsage >= 100) {
085                    usageMutex.wait(timeout);
086                }
087                return percentUsage < 100;
088            }
089        }
090    
091        public boolean isFull() {
092            if (parent != null && parent.isFull()) {
093                return true;
094            }
095            synchronized (usageMutex) {
096                return percentUsage >= 100;
097            }
098        }
099    
100        /**
101         * Tries to increase the usage by value amount but blocks if this object is
102         * currently full.
103         * 
104         * @param value
105         * @throws InterruptedException
106         */
107        public void enqueueUsage(long value) throws InterruptedException {
108            waitForSpace();
109            increaseUsage(value);
110        }
111    
112        /**
113         * Increases the usage by the value amount.
114         * 
115         * @param value
116         */
117        public void increaseUsage(long value) {
118            if (value == 0) {
119                return;
120            }
121            int percentUsage;
122            synchronized (usageMutex) {
123                usage += value;
124                percentUsage = caclPercentUsage();
125            }
126            setPercentUsage(percentUsage);
127            if (parent != null) {
128                ((MemoryUsage)parent).increaseUsage(value);
129            }
130        }
131    
132        /**
133         * Decreases the usage by the value amount.
134         * 
135         * @param value
136         */
137        public void decreaseUsage(long value) {
138            if (value == 0) {
139                return;
140            }
141            int percentUsage;
142            synchronized (usageMutex) {
143                usage -= value;
144                percentUsage = caclPercentUsage();
145            }
146            setPercentUsage(percentUsage);
147            if (parent != null) {
148                parent.decreaseUsage(value);
149            }
150        }
151    
152        protected long retrieveUsage() {
153            return usage;
154        }
155    
156        public long getUsage() {
157            return usage;
158        }
159    
160        public void setUsage(long usage) {
161            this.usage = usage;
162        }
163    }