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1   /**
2    * Copyright The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  
21  package org.apache.hadoop.hbase.util;
22  
23  import java.lang.reflect.Field;
24  import java.lang.reflect.Modifier;
25  import java.util.concurrent.ConcurrentHashMap;
26  import java.util.concurrent.ConcurrentSkipListMap;
27  
28  import org.apache.commons.logging.Log;
29  import org.apache.commons.logging.LogFactory;
30  import org.apache.hadoop.classification.InterfaceAudience;
31  
32  /**
33   * Class for determining the "size" of a class, an attempt to calculate the
34   * actual bytes that an object of this class will occupy in memory
35   *
36   * The core of this class is taken from the Derby project
37   */
38  @InterfaceAudience.Private
39  public class ClassSize {
40    static final Log LOG = LogFactory.getLog(ClassSize.class);
41  
42    private static int nrOfRefsPerObj = 2;
43  
44    /** Array overhead */
45    public static final int ARRAY;
46  
47    /** Overhead for ArrayList(0) */
48    public static final int ARRAYLIST;
49  
50    /** Overhead for ByteBuffer */
51    public static final int BYTE_BUFFER;
52  
53    /** Overhead for an Integer */
54    public static final int INTEGER;
55  
56    /** Overhead for entry in map */
57    public static final int MAP_ENTRY;
58  
59    /** Object overhead is minimum 2 * reference size (8 bytes on 64-bit) */
60    public static final int OBJECT;
61  
62    /** Reference size is 8 bytes on 64-bit, 4 bytes on 32-bit */
63    public static final int REFERENCE;
64  
65    /** String overhead */
66    public static final int STRING;
67  
68    /** Overhead for TreeMap */
69    public static final int TREEMAP;
70  
71    /** Overhead for ConcurrentHashMap */
72    public static final int CONCURRENT_HASHMAP;
73  
74    /** Overhead for ConcurrentHashMap.Entry */
75    public static final int CONCURRENT_HASHMAP_ENTRY;
76  
77    /** Overhead for ConcurrentHashMap.Segment */
78    public static final int CONCURRENT_HASHMAP_SEGMENT;
79  
80    /** Overhead for ConcurrentSkipListMap */
81    public static final int CONCURRENT_SKIPLISTMAP;
82  
83    /** Overhead for ConcurrentSkipListMap Entry */
84    public static final int CONCURRENT_SKIPLISTMAP_ENTRY;
85  
86    /** Overhead for ReentrantReadWriteLock */
87    public static final int REENTRANT_LOCK;
88  
89    /** Overhead for AtomicLong */
90    public static final int ATOMIC_LONG;
91  
92    /** Overhead for AtomicInteger */
93    public static final int ATOMIC_INTEGER;
94  
95    /** Overhead for AtomicBoolean */
96    public static final int ATOMIC_BOOLEAN;
97  
98    /** Overhead for CopyOnWriteArraySet */
99    public static final int COPYONWRITE_ARRAYSET;
100 
101   /** Overhead for CopyOnWriteArrayList */
102   public static final int COPYONWRITE_ARRAYLIST;
103 
104   /** Overhead for timerange */
105   public static final int TIMERANGE;
106 
107   /** Overhead for TimeRangeTracker */
108   public static final int TIMERANGE_TRACKER;
109 
110   /** Overhead for KeyValueSkipListSet */
111   public static final int KEYVALUE_SKIPLIST_SET;
112 
113   /* Are we running on jdk7? */
114   private static final boolean JDK7;
115   static {
116     final String version = System.getProperty("java.version");
117     // Verify String looks like this: 1.6.0_29
118     if (!version.matches("\\d\\.\\d\\..*")) {
119       throw new RuntimeException("Unexpected version format: " + version);
120     }
121     // Convert char to int
122     int major = (int)(version.charAt(0) - '0');
123     int minor = (int)(version.charAt(2) - '0');
124     JDK7 = major == 1 && minor == 7;
125   }
126 
127   /**
128    * Method for reading the arc settings and setting overheads according
129    * to 32-bit or 64-bit architecture.
130    */
131   static {
132     //Default value is set to 8, covering the case when arcModel is unknown
133     if (is32BitJVM()) {
134       REFERENCE = 4;
135     } else {
136       REFERENCE = 8;
137     }
138 
139     OBJECT = 2 * REFERENCE;
140 
141     ARRAY = align(3 * REFERENCE);
142 
143     ARRAYLIST = align(OBJECT + align(REFERENCE) + align(ARRAY) +
144         (2 * Bytes.SIZEOF_INT));
145 
146     //noinspection PointlessArithmeticExpression
147     BYTE_BUFFER = align(OBJECT + align(REFERENCE) + align(ARRAY) +
148         (5 * Bytes.SIZEOF_INT) +
149         (3 * Bytes.SIZEOF_BOOLEAN) + Bytes.SIZEOF_LONG);
150 
151     INTEGER = align(OBJECT + Bytes.SIZEOF_INT);
152 
153     MAP_ENTRY = align(OBJECT + 5 * REFERENCE + Bytes.SIZEOF_BOOLEAN);
154 
155     TREEMAP = align(OBJECT + (2 * Bytes.SIZEOF_INT) + align(7 * REFERENCE));
156 
157     // STRING is different size in jdk6 and jdk7. Just use what we estimate as size rather than
158     // have a conditional on whether jdk7.
159     STRING = (int) estimateBase(String.class, false);
160 
161     // CONCURRENT_HASHMAP is different size in jdk6 and jdk7; it looks like its different between
162     // 23.6-b03 and 23.0-b21. Just use what we estimate as size rather than have a conditional on
163     // whether jdk7.
164     CONCURRENT_HASHMAP = (int) estimateBase(ConcurrentHashMap.class, false);
165 
166     CONCURRENT_HASHMAP_ENTRY = align(REFERENCE + OBJECT + (3 * REFERENCE) +
167         (2 * Bytes.SIZEOF_INT));
168 
169     CONCURRENT_HASHMAP_SEGMENT = align(REFERENCE + OBJECT +
170         (3 * Bytes.SIZEOF_INT) + Bytes.SIZEOF_FLOAT + ARRAY);
171 
172     // The size changes from jdk7 to jdk8, estimate the size rather than use a conditional
173     CONCURRENT_SKIPLISTMAP = (int) estimateBase(ConcurrentSkipListMap.class, false);
174 
175     CONCURRENT_SKIPLISTMAP_ENTRY = align(
176         align(OBJECT + (3 * REFERENCE)) + /* one node per entry */
177         align((OBJECT + (3 * REFERENCE))/2)); /* one index per two entries */
178 
179     REENTRANT_LOCK = align(OBJECT + (3 * REFERENCE));
180 
181     ATOMIC_LONG = align(OBJECT + Bytes.SIZEOF_LONG);
182 
183     ATOMIC_INTEGER = align(OBJECT + Bytes.SIZEOF_INT);
184 
185     ATOMIC_BOOLEAN = align(OBJECT + Bytes.SIZEOF_BOOLEAN);
186 
187     COPYONWRITE_ARRAYSET = align(OBJECT + REFERENCE);
188 
189     COPYONWRITE_ARRAYLIST = align(OBJECT + (2 * REFERENCE) + ARRAY);
190 
191     TIMERANGE = align(ClassSize.OBJECT + Bytes.SIZEOF_LONG * 2 + Bytes.SIZEOF_BOOLEAN);
192 
193     TIMERANGE_TRACKER = align(ClassSize.OBJECT + Bytes.SIZEOF_LONG * 2);
194 
195     KEYVALUE_SKIPLIST_SET = align(OBJECT + REFERENCE);
196   }
197 
198   /**
199    * The estimate of the size of a class instance depends on whether the JVM
200    * uses 32 or 64 bit addresses, that is it depends on the size of an object
201    * reference. It is a linear function of the size of a reference, e.g.
202    * 24 + 5*r where r is the size of a reference (usually 4 or 8 bytes).
203    *
204    * This method returns the coefficients of the linear function, e.g. {24, 5}
205    * in the above example.
206    *
207    * @param cl A class whose instance size is to be estimated
208    * @param debug debug flag
209    * @return an array of 3 integers. The first integer is the size of the
210    * primitives, the second the number of arrays and the third the number of
211    * references.
212    */
213   @SuppressWarnings("unchecked")
214   private static int [] getSizeCoefficients(Class cl, boolean debug) {
215     int primitives = 0;
216     int arrays = 0;
217     //The number of references that a new object takes
218     int references = nrOfRefsPerObj;
219     int index = 0;
220 
221     for ( ; null != cl; cl = cl.getSuperclass()) {
222       Field[] field = cl.getDeclaredFields();
223       if (null != field) {
224         for (Field aField : field) {
225           if (Modifier.isStatic(aField.getModifiers())) continue;
226           Class fieldClass = aField.getType();
227           if (fieldClass.isArray()) {
228             arrays++;
229             references++;
230           } else if (!fieldClass.isPrimitive()) {
231             references++;
232           } else {// Is simple primitive
233             String name = fieldClass.getName();
234 
235             if (name.equals("int") || name.equals("I"))
236               primitives += Bytes.SIZEOF_INT;
237             else if (name.equals("long") || name.equals("J"))
238               primitives += Bytes.SIZEOF_LONG;
239             else if (name.equals("boolean") || name.equals("Z"))
240               primitives += Bytes.SIZEOF_BOOLEAN;
241             else if (name.equals("short") || name.equals("S"))
242               primitives += Bytes.SIZEOF_SHORT;
243             else if (name.equals("byte") || name.equals("B"))
244               primitives += Bytes.SIZEOF_BYTE;
245             else if (name.equals("char") || name.equals("C"))
246               primitives += Bytes.SIZEOF_CHAR;
247             else if (name.equals("float") || name.equals("F"))
248               primitives += Bytes.SIZEOF_FLOAT;
249             else if (name.equals("double") || name.equals("D"))
250               primitives += Bytes.SIZEOF_DOUBLE;
251           }
252           if (debug) {
253             if (LOG.isDebugEnabled()) {
254               LOG.debug("" + index + " " + aField.getName() + " " + aField.getType());
255             }
256           }
257           index++;
258         }
259       }
260     }
261     return new int [] {primitives, arrays, references};
262   }
263 
264   /**
265    * Estimate the static space taken up by a class instance given the
266    * coefficients returned by getSizeCoefficients.
267    *
268    * @param coeff the coefficients
269    *
270    * @param debug debug flag
271    * @return the size estimate, in bytes
272    */
273   private static long estimateBaseFromCoefficients(int [] coeff, boolean debug) {
274     long prealign_size = coeff[0] + align(coeff[1] * ARRAY) + coeff[2] * REFERENCE;
275 
276     // Round up to a multiple of 8
277     long size = align(prealign_size);
278     if(debug) {
279       if (LOG.isDebugEnabled()) {
280         LOG.debug("Primitives=" + coeff[0] + ", arrays=" + coeff[1] +
281             ", references(includes " + nrOfRefsPerObj +
282             " for object overhead)=" + coeff[2] + ", refSize " + REFERENCE +
283             ", size=" + size + ", prealign_size=" + prealign_size);
284       }
285     }
286     return size;
287   }
288 
289   /**
290    * Estimate the static space taken up by the fields of a class. This includes
291    * the space taken up by by references (the pointer) but not by the referenced
292    * object. So the estimated size of an array field does not depend on the size
293    * of the array. Similarly the size of an object (reference) field does not
294    * depend on the object.
295    *
296    * @param cl class
297    * @param debug debug flag
298    * @return the size estimate in bytes.
299    */
300   @SuppressWarnings("unchecked")
301   public static long estimateBase(Class cl, boolean debug) {
302     return estimateBaseFromCoefficients( getSizeCoefficients(cl, debug), debug);
303   }
304 
305   /**
306    * Aligns a number to 8.
307    * @param num number to align to 8
308    * @return smallest number >= input that is a multiple of 8
309    */
310   public static int align(int num) {
311     return (int)(align((long)num));
312   }
313 
314   /**
315    * Aligns a number to 8.
316    * @param num number to align to 8
317    * @return smallest number >= input that is a multiple of 8
318    */
319   public static long align(long num) {
320     //The 7 comes from that the alignSize is 8 which is the number of bytes
321     //stored and sent together
322     return  ((num + 7) >> 3) << 3;
323   }
324 
325   /**
326    * Determines if we are running in a 32-bit JVM. Some unit tests need to
327    * know this too.
328    */
329   public static boolean is32BitJVM() {
330     return System.getProperty("sun.arch.data.model").equals("32");
331   }
332 
333 }
334