1 /*
2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 //
26 // The ObjectHeap is an abstraction over all generations in the VM
27 // It gives access to all present objects and classes.
28 //
29
30 package sun.jvm.hotspot.oops;
31
32 import java.util.*;
33
34 import sun.jvm.hotspot.debugger.*;
35 import sun.jvm.hotspot.gc.cms.*;
36 import sun.jvm.hotspot.gc.shared.*;
37 import sun.jvm.hotspot.gc.epsilon.*;
38 import sun.jvm.hotspot.gc.g1.*;
39 import sun.jvm.hotspot.gc.shenandoah.*;
40 import sun.jvm.hotspot.gc.parallel.*;
41 import sun.jvm.hotspot.gc.z.*;
42 import sun.jvm.hotspot.memory.*;
43 import sun.jvm.hotspot.runtime.*;
44 import sun.jvm.hotspot.types.*;
45 import sun.jvm.hotspot.utilities.*;
46
47 public class ObjectHeap {
48
49 private static final boolean DEBUG;
50
51 static {
52 DEBUG = System.getProperty("sun.jvm.hotspot.oops.ObjectHeap.DEBUG") != null;
53 }
54
55 public ObjectHeap(TypeDataBase db) throws WrongTypeException {
56 // Get commonly used sizes of basic types
57 oopSize = VM.getVM().getOopSize();
58 byteSize = db.getJByteType().getSize();
59 charSize = db.getJCharType().getSize();
60 booleanSize = db.getJBooleanType().getSize();
61 intSize = db.getJIntType().getSize();
62 shortSize = db.getJShortType().getSize();
63 longSize = db.getJLongType().getSize();
64 floatSize = db.getJFloatType().getSize();
65 doubleSize = db.getJDoubleType().getSize();
66 }
67
68 /** Comparison operation for oops, either or both of which may be null */
69 public boolean equal(Oop o1, Oop o2) {
70 if (o1 != null) return o1.equals(o2);
71 return (o2 == null);
72 }
73
74 // Cached sizes of basic types
75 private long oopSize;
76 private long byteSize;
77 private long charSize;
78 private long booleanSize;
79 private long intSize;
80 private long shortSize;
81 private long longSize;
82 private long floatSize;
83 private long doubleSize;
84
85 public long getOopSize() { return oopSize; }
86 public long getByteSize() { return byteSize; }
87 public long getCharSize() { return charSize; }
88 public long getBooleanSize() { return booleanSize; }
89 public long getIntSize() { return intSize; }
90 public long getShortSize() { return shortSize; }
91 public long getLongSize() { return longSize; }
92 public long getFloatSize() { return floatSize; }
93 public long getDoubleSize() { return doubleSize; }
94
95 /** an interface to filter objects while walking heap */
96 public static interface ObjectFilter {
97 public boolean canInclude(Oop obj);
98 }
99
100 /** The base heap iteration mechanism */
101 public void iterate(HeapVisitor visitor) {
102 iterateLiveRegions(collectLiveRegions(), visitor, null);
103 }
104
105 /** iterate objects satisfying a specified ObjectFilter */
106 public void iterate(HeapVisitor visitor, ObjectFilter of) {
107 iterateLiveRegions(collectLiveRegions(), visitor, of);
108 }
109
110 /** iterate objects of given Klass. param 'includeSubtypes' tells whether to
111 * include objects of subtypes or not */
112 public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k, boolean includeSubtypes) {
113 if (includeSubtypes) {
114 if (k.isFinal()) {
115 // do the simpler "exact" klass loop
116 iterateExact(visitor, k);
117 } else {
118 iterateSubtypes(visitor, k);
119 }
120 } else {
121 // there can no object of abstract classes and interfaces
122 if (!k.isAbstract() && !k.isInterface()) {
123 iterateExact(visitor, k);
124 }
125 }
126 }
127
128 /** iterate objects of given Klass (objects of subtypes included) */
129 public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k) {
130 iterateObjectsOfKlass(visitor, k, true);
131 }
132
133 /** This routine can be used to iterate through the heap at an
134 extremely low level (stepping word-by-word) to provide the
135 ability to do very low-level debugging */
136 public void iterateRaw(RawHeapVisitor visitor) {
137 List liveRegions = collectLiveRegions();
138
139 // Summarize size
140 long totalSize = 0;
141 for (int i = 0; i < liveRegions.size(); i += 2) {
142 Address bottom = (Address) liveRegions.get(i);
143 Address top = (Address) liveRegions.get(i+1);
144 totalSize += top.minus(bottom);
145 }
146 visitor.prologue(totalSize);
147
148 for (int i = 0; i < liveRegions.size(); i += 2) {
149 Address bottom = (Address) liveRegions.get(i);
150 Address top = (Address) liveRegions.get(i+1);
151
152 // Traverses the space from bottom to top
153 while (bottom.lessThan(top)) {
154 visitor.visitAddress(bottom);
155 bottom = bottom.addOffsetTo(VM.getVM().getAddressSize());
156 }
157 }
158
159 visitor.epilogue();
160 }
161
162 public boolean isValidMethod(Address handle) {
163 try {
164 Method m = (Method)Metadata.instantiateWrapperFor(handle);
165 return true;
166 } catch (Exception e) {
167 return false;
168 }
169 }
170
171 // Creates an instance from the Oop hierarchy based based on the handle
172 public Oop newOop(OopHandle handle) {
173 // The only known way to detect the right type of an oop is
174 // traversing the class chain until a well-known klass is recognized.
175 // A more direct solution would require the klasses to expose
176 // the C++ vtbl structure.
177
178 // Handle the null reference
179 if (handle == null) return null;
180
181 // Then check if obj.klass() is one of the root objects
182 Klass klass = Oop.getKlassForOopHandle(handle);
183 if (klass != null) {
184 if (klass instanceof TypeArrayKlass) return new TypeArray(handle, this);
185 if (klass instanceof ObjArrayKlass) return new ObjArray(handle, this);
186 if (klass instanceof InstanceKlass) return new Instance(handle, this);
187 }
188
189 if (DEBUG) {
190 System.err.println("Unknown oop at " + handle);
191 System.err.println("Oop's klass is " + klass);
192 }
193
194 throw new UnknownOopException();
195 }
196
197 // Print all objects in the object heap
198 public void print() {
199 HeapPrinter printer = new HeapPrinter(System.out);
200 iterate(printer);
201 }
202
203 //---------------------------------------------------------------------------
204 // Internals only below this point
205 //
206
207 private void iterateExact(HeapVisitor visitor, final Klass k) {
208 iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() {
209 public boolean canInclude(Oop obj) {
210 Klass tk = obj.getKlass();
211 // null Klass is seen sometimes!
212 return (tk != null && tk.equals(k));
213 }
214 });
215 }
216
217 private void iterateSubtypes(HeapVisitor visitor, final Klass k) {
218 iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() {
219 public boolean canInclude(Oop obj) {
220 Klass tk = obj.getKlass();
221 // null Klass is seen sometimes!
222 return (tk != null && tk.isSubtypeOf(k));
223 }
224 });
225 }
226
227 private void iterateLiveRegions(List liveRegions, HeapVisitor visitor, ObjectFilter of) {
228 // Summarize size
229 long totalSize = 0;
230 for (int i = 0; i < liveRegions.size(); i += 2) {
231 Address bottom = (Address) liveRegions.get(i);
232 Address top = (Address) liveRegions.get(i+1);
233 totalSize += top.minus(bottom);
234 }
235 visitor.prologue(totalSize);
236
237 CompactibleFreeListSpace cmsSpaceOld = null;
238 CollectedHeap heap = VM.getVM().getUniverse().heap();
239
240 if (heap instanceof GenCollectedHeap) {
241 GenCollectedHeap genHeap = (GenCollectedHeap) heap;
242 Generation genOld = genHeap.getGen(1);
243 if (genOld instanceof ConcurrentMarkSweepGeneration) {
244 ConcurrentMarkSweepGeneration concGen = (ConcurrentMarkSweepGeneration)genOld;
245 cmsSpaceOld = concGen.cmsSpace();
246 }
247 }
248
249 for (int i = 0; i < liveRegions.size(); i += 2) {
250 Address bottom = (Address) liveRegions.get(i);
251 Address top = (Address) liveRegions.get(i+1);
252
253 try {
254 // Traverses the space from bottom to top
255 OopHandle handle = bottom.addOffsetToAsOopHandle(0);
256
257 while (handle.lessThan(top)) {
258 Oop obj = null;
259
260 try {
261 obj = newOop(handle);
262 } catch (UnknownOopException exp) {
263 if (DEBUG) {
264 throw new RuntimeException(" UnknownOopException " + exp);
265 }
266 }
267 if (obj == null) {
268 //Find the object size using Printezis bits and skip over
269 long size = 0;
270
271 if ( (cmsSpaceOld != null) && cmsSpaceOld.contains(handle) ){
272 size = cmsSpaceOld.collector().blockSizeUsingPrintezisBits(handle);
273 }
274
275 if (size <= 0) {
276 //Either Printezis bits not set or handle is not in cms space.
277 throw new UnknownOopException();
278 }
279
280 handle = handle.addOffsetToAsOopHandle(CompactibleFreeListSpace.adjustObjectSizeInBytes(size));
281 continue;
282 }
283 if (of == null || of.canInclude(obj)) {
284 if (visitor.doObj(obj)) {
285 // doObj() returns true to abort this loop.
286 break;
287 }
288 }
289 if ( (cmsSpaceOld != null) && cmsSpaceOld.contains(handle)) {
290 handle = handle.addOffsetToAsOopHandle(CompactibleFreeListSpace.adjustObjectSizeInBytes(obj.getObjectSize()) );
291 } else {
292 handle = handle.addOffsetToAsOopHandle(obj.getObjectSize());
293 }
294 }
295 }
296 catch (AddressException e) {
297 // This is okay at the top of these regions
298 }
299 catch (UnknownOopException e) {
300 // This is okay at the top of these regions
301 }
302 }
303
304 visitor.epilogue();
305 }
306
307 private void addLiveRegions(String name, List input, List output) {
308 for (Iterator itr = input.iterator(); itr.hasNext();) {
309 MemRegion reg = (MemRegion) itr.next();
310 Address top = reg.end();
311 Address bottom = reg.start();
312 if (Assert.ASSERTS_ENABLED) {
313 Assert.that(top != null, "top address in a live region should not be null");
314 }
315 if (Assert.ASSERTS_ENABLED) {
316 Assert.that(bottom != null, "bottom address in a live region should not be null");
317 }
318 output.add(top);
319 output.add(bottom);
320 if (DEBUG) {
321 System.err.println("Live region: " + name + ": " + bottom + ", " + top);
322 }
323 }
324 }
325
326 private class LiveRegionsCollector implements SpaceClosure {
327 LiveRegionsCollector(List l) {
328 liveRegions = l;
329 }
330
331 public void doSpace(Space s) {
332 addLiveRegions(s.toString(), s.getLiveRegions(), liveRegions);
333 }
334 private List liveRegions;
335 }
336
337 // Returns a List<Address> where the addresses come in pairs. These
338 // designate the live regions of the heap.
339 private List collectLiveRegions() {
340 // We want to iterate through all live portions of the heap, but
341 // do not want to abort the heap traversal prematurely if we find
342 // a problem (like an allocated but uninitialized object at the
343 // top of a generation). To do this we enumerate all generations'
344 // bottom and top regions, and factor in TLABs if necessary.
345
346 // List<Address>. Addresses come in pairs.
347 List liveRegions = new ArrayList();
348 LiveRegionsCollector lrc = new LiveRegionsCollector(liveRegions);
349
350 CollectedHeap heap = VM.getVM().getUniverse().heap();
351
352 if (heap instanceof GenCollectedHeap) {
353 GenCollectedHeap genHeap = (GenCollectedHeap) heap;
354 // Run through all generations, obtaining bottom-top pairs.
355 for (int i = 0; i < genHeap.nGens(); i++) {
356 Generation gen = genHeap.getGen(i);
357 gen.spaceIterate(lrc, true);
358 }
359 } else if (heap instanceof ParallelScavengeHeap) {
360 ParallelScavengeHeap psh = (ParallelScavengeHeap) heap;
361 PSYoungGen youngGen = psh.youngGen();
362 // Add eden space
363 addLiveRegions("eden", youngGen.edenSpace().getLiveRegions(), liveRegions);
364 // Add from-space but not to-space
365 addLiveRegions("from", youngGen.fromSpace().getLiveRegions(), liveRegions);
366 PSOldGen oldGen = psh.oldGen();
367 addLiveRegions("old ", oldGen.objectSpace().getLiveRegions(), liveRegions);
368 } else if (heap instanceof G1CollectedHeap) {
369 G1CollectedHeap g1h = (G1CollectedHeap) heap;
370 g1h.heapRegionIterate(lrc);
371 } else if (heap instanceof ShenandoahHeap) {
372 // Operation (currently) not supported with Shenandoah GC. Print
373 // a warning and leave the list of live regions empty.
374 System.err.println("Warning: Operation not supported with Shenandoah GC");
375 } else if (heap instanceof ZCollectedHeap) {
376 // Operation (currently) not supported with ZGC. Print
377 // a warning and leave the list of live regions empty.
378 System.err.println("Warning: Operation not supported with ZGC");
379 } else if (heap instanceof EpsilonHeap) {
380 EpsilonHeap eh = (EpsilonHeap) heap;
381 liveRegions.add(eh.space().top());
382 liveRegions.add(eh.space().bottom());
383 } else {
384 if (Assert.ASSERTS_ENABLED) {
385 Assert.that(false, "Unexpected CollectedHeap type: " + heap.getClass().getName());
386 }
387 }
388
389 // If UseTLAB is enabled, snip out regions associated with TLABs'
390 // dead regions. Note that TLABs can be present in any generation.
391
392 // FIXME: consider adding fewer boundaries to live region list.
393 // Theoretically only need to stop at TLAB's top and resume at its
394 // end.
395
396 if (VM.getVM().getUseTLAB()) {
397 for (JavaThread thread = VM.getVM().getThreads().first(); thread != null; thread = thread.next()) {
398 ThreadLocalAllocBuffer tlab = thread.tlab();
399 if (tlab.start() != null) {
400 if ((tlab.top() == null) || (tlab.end() == null)) {
401 System.err.print("Warning: skipping invalid TLAB for thread ");
402 thread.printThreadIDOn(System.err);
403 System.err.println();
404 } else {
405 if (DEBUG) {
406 System.err.print("TLAB for " + thread.getThreadName() + ", #");
407 thread.printThreadIDOn(System.err);
408 System.err.print(": ");
409 tlab.printOn(System.err);
410 }
411 // Go from:
412 // - below start() to start()
413 // - start() to top()
414 // - end() and above
415 liveRegions.add(tlab.start());
416 liveRegions.add(tlab.start());
417 liveRegions.add(tlab.top());
418 liveRegions.add(tlab.hardEnd());
419 }
420 }
421 }
422 }
423
424 // Now sort live regions
425 sortLiveRegions(liveRegions);
426
427 if (Assert.ASSERTS_ENABLED) {
428 Assert.that(liveRegions.size() % 2 == 0, "Must have even number of region boundaries");
429 }
430
431 if (DEBUG) {
432 System.err.println("liveRegions:");
433 for (int i = 0; i < liveRegions.size(); i += 2) {
434 Address bottom = (Address) liveRegions.get(i);
435 Address top = (Address) liveRegions.get(i+1);
436 System.err.println(" " + bottom + " - " + top);
437 }
438 }
439
440 return liveRegions;
441 }
442
443 private void sortLiveRegions(List liveRegions) {
444 Collections.sort(liveRegions, new Comparator() {
445 public int compare(Object o1, Object o2) {
446 Address a1 = (Address) o1;
447 Address a2 = (Address) o2;
448 if (AddressOps.lt(a1, a2)) {
449 return -1;
450 } else if (AddressOps.gt(a1, a2)) {
451 return 1;
452 }
453 return 0;
454 }
455 });
456 }
457 }