Wed, 23 Sep 2009 23:56:15 -0700
Merge
1 /*
2 * Copyright 2001-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_binaryTreeDictionary.cpp.incl"
28 ////////////////////////////////////////////////////////////////////////////////
29 // A binary tree based search structure for free blocks.
30 // This is currently used in the Concurrent Mark&Sweep implementation.
31 ////////////////////////////////////////////////////////////////////////////////
33 TreeChunk* TreeChunk::as_TreeChunk(FreeChunk* fc) {
34 // Do some assertion checking here.
35 return (TreeChunk*) fc;
36 }
38 void TreeChunk::verifyTreeChunkList() const {
39 TreeChunk* nextTC = (TreeChunk*)next();
40 if (prev() != NULL) { // interior list node shouldn'r have tree fields
41 guarantee(embedded_list()->parent() == NULL && embedded_list()->left() == NULL &&
42 embedded_list()->right() == NULL, "should be clear");
43 }
44 if (nextTC != NULL) {
45 guarantee(as_TreeChunk(nextTC->prev()) == this, "broken chain");
46 guarantee(nextTC->size() == size(), "wrong size");
47 nextTC->verifyTreeChunkList();
48 }
49 }
52 TreeList* TreeList::as_TreeList(TreeChunk* tc) {
53 // This first free chunk in the list will be the tree list.
54 assert(tc->size() >= sizeof(TreeChunk), "Chunk is too small for a TreeChunk");
55 TreeList* tl = tc->embedded_list();
56 tc->set_list(tl);
57 #ifdef ASSERT
58 tl->set_protecting_lock(NULL);
59 #endif
60 tl->set_hint(0);
61 tl->set_size(tc->size());
62 tl->link_head(tc);
63 tl->link_tail(tc);
64 tl->set_count(1);
65 tl->init_statistics();
66 tl->setParent(NULL);
67 tl->setLeft(NULL);
68 tl->setRight(NULL);
69 return tl;
70 }
71 TreeList* TreeList::as_TreeList(HeapWord* addr, size_t size) {
72 TreeChunk* tc = (TreeChunk*) addr;
73 assert(size >= sizeof(TreeChunk), "Chunk is too small for a TreeChunk");
74 // The space in the heap will have been mangled initially but
75 // is not remangled when a free chunk is returned to the free list
76 // (since it is used to maintain the chunk on the free list).
77 assert((ZapUnusedHeapArea &&
78 SpaceMangler::is_mangled((HeapWord*) tc->size_addr()) &&
79 SpaceMangler::is_mangled((HeapWord*) tc->prev_addr()) &&
80 SpaceMangler::is_mangled((HeapWord*) tc->next_addr())) ||
81 (tc->size() == 0 && tc->prev() == NULL && tc->next() == NULL),
82 "Space should be clear or mangled");
83 tc->setSize(size);
84 tc->linkPrev(NULL);
85 tc->linkNext(NULL);
86 TreeList* tl = TreeList::as_TreeList(tc);
87 return tl;
88 }
90 TreeList* TreeList::removeChunkReplaceIfNeeded(TreeChunk* tc) {
92 TreeList* retTL = this;
93 FreeChunk* list = head();
94 assert(!list || list != list->next(), "Chunk on list twice");
95 assert(tc != NULL, "Chunk being removed is NULL");
96 assert(parent() == NULL || this == parent()->left() ||
97 this == parent()->right(), "list is inconsistent");
98 assert(tc->isFree(), "Header is not marked correctly");
99 assert(head() == NULL || head()->prev() == NULL, "list invariant");
100 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
102 FreeChunk* prevFC = tc->prev();
103 TreeChunk* nextTC = TreeChunk::as_TreeChunk(tc->next());
104 assert(list != NULL, "should have at least the target chunk");
106 // Is this the first item on the list?
107 if (tc == list) {
108 // The "getChunk..." functions for a TreeList will not return the
109 // first chunk in the list unless it is the last chunk in the list
110 // because the first chunk is also acting as the tree node.
111 // When coalescing happens, however, the first chunk in the a tree
112 // list can be the start of a free range. Free ranges are removed
113 // from the free lists so that they are not available to be
114 // allocated when the sweeper yields (giving up the free list lock)
115 // to allow mutator activity. If this chunk is the first in the
116 // list and is not the last in the list, do the work to copy the
117 // TreeList from the first chunk to the next chunk and update all
118 // the TreeList pointers in the chunks in the list.
119 if (nextTC == NULL) {
120 assert(prevFC == NULL, "Not last chunk in the list")
121 set_tail(NULL);
122 set_head(NULL);
123 } else {
124 // copy embedded list.
125 nextTC->set_embedded_list(tc->embedded_list());
126 retTL = nextTC->embedded_list();
127 // Fix the pointer to the list in each chunk in the list.
128 // This can be slow for a long list. Consider having
129 // an option that does not allow the first chunk on the
130 // list to be coalesced.
131 for (TreeChunk* curTC = nextTC; curTC != NULL;
132 curTC = TreeChunk::as_TreeChunk(curTC->next())) {
133 curTC->set_list(retTL);
134 }
135 // Fix the parent to point to the new TreeList.
136 if (retTL->parent() != NULL) {
137 if (this == retTL->parent()->left()) {
138 retTL->parent()->setLeft(retTL);
139 } else {
140 assert(this == retTL->parent()->right(), "Parent is incorrect");
141 retTL->parent()->setRight(retTL);
142 }
143 }
144 // Fix the children's parent pointers to point to the
145 // new list.
146 assert(right() == retTL->right(), "Should have been copied");
147 if (retTL->right() != NULL) {
148 retTL->right()->setParent(retTL);
149 }
150 assert(left() == retTL->left(), "Should have been copied");
151 if (retTL->left() != NULL) {
152 retTL->left()->setParent(retTL);
153 }
154 retTL->link_head(nextTC);
155 assert(nextTC->isFree(), "Should be a free chunk");
156 }
157 } else {
158 if (nextTC == NULL) {
159 // Removing chunk at tail of list
160 link_tail(prevFC);
161 }
162 // Chunk is interior to the list
163 prevFC->linkAfter(nextTC);
164 }
166 // Below this point the embeded TreeList being used for the
167 // tree node may have changed. Don't use "this"
168 // TreeList*.
169 // chunk should still be a free chunk (bit set in _prev)
170 assert(!retTL->head() || retTL->size() == retTL->head()->size(),
171 "Wrong sized chunk in list");
172 debug_only(
173 tc->linkPrev(NULL);
174 tc->linkNext(NULL);
175 tc->set_list(NULL);
176 bool prev_found = false;
177 bool next_found = false;
178 for (FreeChunk* curFC = retTL->head();
179 curFC != NULL; curFC = curFC->next()) {
180 assert(curFC != tc, "Chunk is still in list");
181 if (curFC == prevFC) {
182 prev_found = true;
183 }
184 if (curFC == nextTC) {
185 next_found = true;
186 }
187 }
188 assert(prevFC == NULL || prev_found, "Chunk was lost from list");
189 assert(nextTC == NULL || next_found, "Chunk was lost from list");
190 assert(retTL->parent() == NULL ||
191 retTL == retTL->parent()->left() ||
192 retTL == retTL->parent()->right(),
193 "list is inconsistent");
194 )
195 retTL->decrement_count();
197 assert(tc->isFree(), "Should still be a free chunk");
198 assert(retTL->head() == NULL || retTL->head()->prev() == NULL,
199 "list invariant");
200 assert(retTL->tail() == NULL || retTL->tail()->next() == NULL,
201 "list invariant");
202 return retTL;
203 }
204 void TreeList::returnChunkAtTail(TreeChunk* chunk) {
205 assert(chunk != NULL, "returning NULL chunk");
206 assert(chunk->list() == this, "list should be set for chunk");
207 assert(tail() != NULL, "The tree list is embedded in the first chunk");
208 // which means that the list can never be empty.
209 assert(!verifyChunkInFreeLists(chunk), "Double entry");
210 assert(head() == NULL || head()->prev() == NULL, "list invariant");
211 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
213 FreeChunk* fc = tail();
214 fc->linkAfter(chunk);
215 link_tail(chunk);
217 assert(!tail() || size() == tail()->size(), "Wrong sized chunk in list");
218 increment_count();
219 debug_only(increment_returnedBytes_by(chunk->size()*sizeof(HeapWord));)
220 assert(head() == NULL || head()->prev() == NULL, "list invariant");
221 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
222 }
224 // Add this chunk at the head of the list. "At the head of the list"
225 // is defined to be after the chunk pointer to by head(). This is
226 // because the TreeList is embedded in the first TreeChunk in the
227 // list. See the definition of TreeChunk.
228 void TreeList::returnChunkAtHead(TreeChunk* chunk) {
229 assert(chunk->list() == this, "list should be set for chunk");
230 assert(head() != NULL, "The tree list is embedded in the first chunk");
231 assert(chunk != NULL, "returning NULL chunk");
232 assert(!verifyChunkInFreeLists(chunk), "Double entry");
233 assert(head() == NULL || head()->prev() == NULL, "list invariant");
234 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
236 FreeChunk* fc = head()->next();
237 if (fc != NULL) {
238 chunk->linkAfter(fc);
239 } else {
240 assert(tail() == NULL, "List is inconsistent");
241 link_tail(chunk);
242 }
243 head()->linkAfter(chunk);
244 assert(!head() || size() == head()->size(), "Wrong sized chunk in list");
245 increment_count();
246 debug_only(increment_returnedBytes_by(chunk->size()*sizeof(HeapWord));)
247 assert(head() == NULL || head()->prev() == NULL, "list invariant");
248 assert(tail() == NULL || tail()->next() == NULL, "list invariant");
249 }
251 TreeChunk* TreeList::head_as_TreeChunk() {
252 assert(head() == NULL || TreeChunk::as_TreeChunk(head())->list() == this,
253 "Wrong type of chunk?");
254 return TreeChunk::as_TreeChunk(head());
255 }
257 TreeChunk* TreeList::first_available() {
258 guarantee(head() != NULL, "The head of the list cannot be NULL");
259 FreeChunk* fc = head()->next();
260 TreeChunk* retTC;
261 if (fc == NULL) {
262 retTC = head_as_TreeChunk();
263 } else {
264 retTC = TreeChunk::as_TreeChunk(fc);
265 }
266 assert(retTC->list() == this, "Wrong type of chunk.");
267 return retTC;
268 }
270 BinaryTreeDictionary::BinaryTreeDictionary(MemRegion mr, bool splay):
271 _splay(splay)
272 {
273 assert(mr.byte_size() > MIN_TREE_CHUNK_SIZE, "minimum chunk size");
275 reset(mr);
276 assert(root()->left() == NULL, "reset check failed");
277 assert(root()->right() == NULL, "reset check failed");
278 assert(root()->head()->next() == NULL, "reset check failed");
279 assert(root()->head()->prev() == NULL, "reset check failed");
280 assert(totalSize() == root()->size(), "reset check failed");
281 assert(totalFreeBlocks() == 1, "reset check failed");
282 }
284 void BinaryTreeDictionary::inc_totalSize(size_t inc) {
285 _totalSize = _totalSize + inc;
286 }
288 void BinaryTreeDictionary::dec_totalSize(size_t dec) {
289 _totalSize = _totalSize - dec;
290 }
292 void BinaryTreeDictionary::reset(MemRegion mr) {
293 assert(mr.byte_size() > MIN_TREE_CHUNK_SIZE, "minimum chunk size");
294 set_root(TreeList::as_TreeList(mr.start(), mr.word_size()));
295 set_totalSize(mr.word_size());
296 set_totalFreeBlocks(1);
297 }
299 void BinaryTreeDictionary::reset(HeapWord* addr, size_t byte_size) {
300 MemRegion mr(addr, heap_word_size(byte_size));
301 reset(mr);
302 }
304 void BinaryTreeDictionary::reset() {
305 set_root(NULL);
306 set_totalSize(0);
307 set_totalFreeBlocks(0);
308 }
310 // Get a free block of size at least size from tree, or NULL.
311 // If a splay step is requested, the removal algorithm (only) incorporates
312 // a splay step as follows:
313 // . the search proceeds down the tree looking for a possible
314 // match. At the (closest) matching location, an appropriate splay step is applied
315 // (zig, zig-zig or zig-zag). A chunk of the appropriate size is then returned
316 // if available, and if it's the last chunk, the node is deleted. A deteleted
317 // node is replaced in place by its tree successor.
318 TreeChunk*
319 BinaryTreeDictionary::getChunkFromTree(size_t size, Dither dither, bool splay)
320 {
321 TreeList *curTL, *prevTL;
322 TreeChunk* retTC = NULL;
323 assert(size >= MIN_TREE_CHUNK_SIZE, "minimum chunk size");
324 if (FLSVerifyDictionary) {
325 verifyTree();
326 }
327 // starting at the root, work downwards trying to find match.
328 // Remember the last node of size too great or too small.
329 for (prevTL = curTL = root(); curTL != NULL;) {
330 if (curTL->size() == size) { // exact match
331 break;
332 }
333 prevTL = curTL;
334 if (curTL->size() < size) { // proceed to right sub-tree
335 curTL = curTL->right();
336 } else { // proceed to left sub-tree
337 assert(curTL->size() > size, "size inconsistency");
338 curTL = curTL->left();
339 }
340 }
341 if (curTL == NULL) { // couldn't find exact match
342 // try and find the next larger size by walking back up the search path
343 for (curTL = prevTL; curTL != NULL;) {
344 if (curTL->size() >= size) break;
345 else curTL = curTL->parent();
346 }
347 assert(curTL == NULL || curTL->count() > 0,
348 "An empty list should not be in the tree");
349 }
350 if (curTL != NULL) {
351 assert(curTL->size() >= size, "size inconsistency");
352 if (UseCMSAdaptiveFreeLists) {
354 // A candidate chunk has been found. If it is already under
355 // populated, get a chunk associated with the hint for this
356 // chunk.
357 if (curTL->surplus() <= 0) {
358 /* Use the hint to find a size with a surplus, and reset the hint. */
359 TreeList* hintTL = curTL;
360 while (hintTL->hint() != 0) {
361 assert(hintTL->hint() == 0 || hintTL->hint() > hintTL->size(),
362 "hint points in the wrong direction");
363 hintTL = findList(hintTL->hint());
364 assert(curTL != hintTL, "Infinite loop");
365 if (hintTL == NULL ||
366 hintTL == curTL /* Should not happen but protect against it */ ) {
367 // No useful hint. Set the hint to NULL and go on.
368 curTL->set_hint(0);
369 break;
370 }
371 assert(hintTL->size() > size, "hint is inconsistent");
372 if (hintTL->surplus() > 0) {
373 // The hint led to a list that has a surplus. Use it.
374 // Set the hint for the candidate to an overpopulated
375 // size.
376 curTL->set_hint(hintTL->size());
377 // Change the candidate.
378 curTL = hintTL;
379 break;
380 }
381 // The evm code reset the hint of the candidate as
382 // at an interrim point. Why? Seems like this leaves
383 // the hint pointing to a list that didn't work.
384 // curTL->set_hint(hintTL->size());
385 }
386 }
387 }
388 // don't waste time splaying if chunk's singleton
389 if (splay && curTL->head()->next() != NULL) {
390 semiSplayStep(curTL);
391 }
392 retTC = curTL->first_available();
393 assert((retTC != NULL) && (curTL->count() > 0),
394 "A list in the binary tree should not be NULL");
395 assert(retTC->size() >= size,
396 "A chunk of the wrong size was found");
397 removeChunkFromTree(retTC);
398 assert(retTC->isFree(), "Header is not marked correctly");
399 }
401 if (FLSVerifyDictionary) {
402 verify();
403 }
404 return retTC;
405 }
407 TreeList* BinaryTreeDictionary::findList(size_t size) const {
408 TreeList* curTL;
409 for (curTL = root(); curTL != NULL;) {
410 if (curTL->size() == size) { // exact match
411 break;
412 }
414 if (curTL->size() < size) { // proceed to right sub-tree
415 curTL = curTL->right();
416 } else { // proceed to left sub-tree
417 assert(curTL->size() > size, "size inconsistency");
418 curTL = curTL->left();
419 }
420 }
421 return curTL;
422 }
425 bool BinaryTreeDictionary::verifyChunkInFreeLists(FreeChunk* tc) const {
426 size_t size = tc->size();
427 TreeList* tl = findList(size);
428 if (tl == NULL) {
429 return false;
430 } else {
431 return tl->verifyChunkInFreeLists(tc);
432 }
433 }
435 FreeChunk* BinaryTreeDictionary::findLargestDict() const {
436 TreeList *curTL = root();
437 if (curTL != NULL) {
438 while(curTL->right() != NULL) curTL = curTL->right();
439 return curTL->first_available();
440 } else {
441 return NULL;
442 }
443 }
445 // Remove the current chunk from the tree. If it is not the last
446 // chunk in a list on a tree node, just unlink it.
447 // If it is the last chunk in the list (the next link is NULL),
448 // remove the node and repair the tree.
449 TreeChunk*
450 BinaryTreeDictionary::removeChunkFromTree(TreeChunk* tc) {
451 assert(tc != NULL, "Should not call with a NULL chunk");
452 assert(tc->isFree(), "Header is not marked correctly");
454 TreeList *newTL, *parentTL;
455 TreeChunk* retTC;
456 TreeList* tl = tc->list();
457 debug_only(
458 bool removing_only_chunk = false;
459 if (tl == _root) {
460 if ((_root->left() == NULL) && (_root->right() == NULL)) {
461 if (_root->count() == 1) {
462 assert(_root->head() == tc, "Should only be this one chunk");
463 removing_only_chunk = true;
464 }
465 }
466 }
467 )
468 assert(tl != NULL, "List should be set");
469 assert(tl->parent() == NULL || tl == tl->parent()->left() ||
470 tl == tl->parent()->right(), "list is inconsistent");
472 bool complicatedSplice = false;
474 retTC = tc;
475 // Removing this chunk can have the side effect of changing the node
476 // (TreeList*) in the tree. If the node is the root, update it.
477 TreeList* replacementTL = tl->removeChunkReplaceIfNeeded(tc);
478 assert(tc->isFree(), "Chunk should still be free");
479 assert(replacementTL->parent() == NULL ||
480 replacementTL == replacementTL->parent()->left() ||
481 replacementTL == replacementTL->parent()->right(),
482 "list is inconsistent");
483 if (tl == root()) {
484 assert(replacementTL->parent() == NULL, "Incorrectly replacing root");
485 set_root(replacementTL);
486 }
487 debug_only(
488 if (tl != replacementTL) {
489 assert(replacementTL->head() != NULL,
490 "If the tree list was replaced, it should not be a NULL list");
491 TreeList* rhl = replacementTL->head_as_TreeChunk()->list();
492 TreeList* rtl = TreeChunk::as_TreeChunk(replacementTL->tail())->list();
493 assert(rhl == replacementTL, "Broken head");
494 assert(rtl == replacementTL, "Broken tail");
495 assert(replacementTL->size() == tc->size(), "Broken size");
496 }
497 )
499 // Does the tree need to be repaired?
500 if (replacementTL->count() == 0) {
501 assert(replacementTL->head() == NULL &&
502 replacementTL->tail() == NULL, "list count is incorrect");
503 // Find the replacement node for the (soon to be empty) node being removed.
504 // if we have a single (or no) child, splice child in our stead
505 if (replacementTL->left() == NULL) {
506 // left is NULL so pick right. right may also be NULL.
507 newTL = replacementTL->right();
508 debug_only(replacementTL->clearRight();)
509 } else if (replacementTL->right() == NULL) {
510 // right is NULL
511 newTL = replacementTL->left();
512 debug_only(replacementTL->clearLeft();)
513 } else { // we have both children, so, by patriarchal convention,
514 // my replacement is least node in right sub-tree
515 complicatedSplice = true;
516 newTL = removeTreeMinimum(replacementTL->right());
517 assert(newTL != NULL && newTL->left() == NULL &&
518 newTL->right() == NULL, "sub-tree minimum exists");
519 }
520 // newTL is the replacement for the (soon to be empty) node.
521 // newTL may be NULL.
522 // should verify; we just cleanly excised our replacement
523 if (FLSVerifyDictionary) {
524 verifyTree();
525 }
526 // first make newTL my parent's child
527 if ((parentTL = replacementTL->parent()) == NULL) {
528 // newTL should be root
529 assert(tl == root(), "Incorrectly replacing root");
530 set_root(newTL);
531 if (newTL != NULL) {
532 newTL->clearParent();
533 }
534 } else if (parentTL->right() == replacementTL) {
535 // replacementTL is a right child
536 parentTL->setRight(newTL);
537 } else { // replacementTL is a left child
538 assert(parentTL->left() == replacementTL, "should be left child");
539 parentTL->setLeft(newTL);
540 }
541 debug_only(replacementTL->clearParent();)
542 if (complicatedSplice) { // we need newTL to get replacementTL's
543 // two children
544 assert(newTL != NULL &&
545 newTL->left() == NULL && newTL->right() == NULL,
546 "newTL should not have encumbrances from the past");
547 // we'd like to assert as below:
548 // assert(replacementTL->left() != NULL && replacementTL->right() != NULL,
549 // "else !complicatedSplice");
550 // ... however, the above assertion is too strong because we aren't
551 // guaranteed that replacementTL->right() is still NULL.
552 // Recall that we removed
553 // the right sub-tree minimum from replacementTL.
554 // That may well have been its right
555 // child! So we'll just assert half of the above:
556 assert(replacementTL->left() != NULL, "else !complicatedSplice");
557 newTL->setLeft(replacementTL->left());
558 newTL->setRight(replacementTL->right());
559 debug_only(
560 replacementTL->clearRight();
561 replacementTL->clearLeft();
562 )
563 }
564 assert(replacementTL->right() == NULL &&
565 replacementTL->left() == NULL &&
566 replacementTL->parent() == NULL,
567 "delete without encumbrances");
568 }
570 assert(totalSize() >= retTC->size(), "Incorrect total size");
571 dec_totalSize(retTC->size()); // size book-keeping
572 assert(totalFreeBlocks() > 0, "Incorrect total count");
573 set_totalFreeBlocks(totalFreeBlocks() - 1);
575 assert(retTC != NULL, "null chunk?");
576 assert(retTC->prev() == NULL && retTC->next() == NULL,
577 "should return without encumbrances");
578 if (FLSVerifyDictionary) {
579 verifyTree();
580 }
581 assert(!removing_only_chunk || _root == NULL, "root should be NULL");
582 return TreeChunk::as_TreeChunk(retTC);
583 }
585 // Remove the leftmost node (lm) in the tree and return it.
586 // If lm has a right child, link it to the left node of
587 // the parent of lm.
588 TreeList* BinaryTreeDictionary::removeTreeMinimum(TreeList* tl) {
589 assert(tl != NULL && tl->parent() != NULL, "really need a proper sub-tree");
590 // locate the subtree minimum by walking down left branches
591 TreeList* curTL = tl;
592 for (; curTL->left() != NULL; curTL = curTL->left());
593 // obviously curTL now has at most one child, a right child
594 if (curTL != root()) { // Should this test just be removed?
595 TreeList* parentTL = curTL->parent();
596 if (parentTL->left() == curTL) { // curTL is a left child
597 parentTL->setLeft(curTL->right());
598 } else {
599 // If the list tl has no left child, then curTL may be
600 // the right child of parentTL.
601 assert(parentTL->right() == curTL, "should be a right child");
602 parentTL->setRight(curTL->right());
603 }
604 } else {
605 // The only use of this method would not pass the root of the
606 // tree (as indicated by the assertion above that the tree list
607 // has a parent) but the specification does not explicitly exclude the
608 // passing of the root so accomodate it.
609 set_root(NULL);
610 }
611 debug_only(
612 curTL->clearParent(); // Test if this needs to be cleared
613 curTL->clearRight(); // recall, above, left child is already null
614 )
615 // we just excised a (non-root) node, we should still verify all tree invariants
616 if (FLSVerifyDictionary) {
617 verifyTree();
618 }
619 return curTL;
620 }
622 // Based on a simplification of the algorithm by Sleator and Tarjan (JACM 1985).
623 // The simplifications are the following:
624 // . we splay only when we delete (not when we insert)
625 // . we apply a single spay step per deletion/access
626 // By doing such partial splaying, we reduce the amount of restructuring,
627 // while getting a reasonably efficient search tree (we think).
628 // [Measurements will be needed to (in)validate this expectation.]
630 void BinaryTreeDictionary::semiSplayStep(TreeList* tc) {
631 // apply a semi-splay step at the given node:
632 // . if root, norting needs to be done
633 // . if child of root, splay once
634 // . else zig-zig or sig-zag depending on path from grandparent
635 if (root() == tc) return;
636 warning("*** Splaying not yet implemented; "
637 "tree operations may be inefficient ***");
638 }
640 void BinaryTreeDictionary::insertChunkInTree(FreeChunk* fc) {
641 TreeList *curTL, *prevTL;
642 size_t size = fc->size();
644 assert(size >= MIN_TREE_CHUNK_SIZE, "too small to be a TreeList");
645 if (FLSVerifyDictionary) {
646 verifyTree();
647 }
648 // XXX: do i need to clear the FreeChunk fields, let me do it just in case
649 // Revisit this later
651 fc->clearNext();
652 fc->linkPrev(NULL);
654 // work down from the _root, looking for insertion point
655 for (prevTL = curTL = root(); curTL != NULL;) {
656 if (curTL->size() == size) // exact match
657 break;
658 prevTL = curTL;
659 if (curTL->size() > size) { // follow left branch
660 curTL = curTL->left();
661 } else { // follow right branch
662 assert(curTL->size() < size, "size inconsistency");
663 curTL = curTL->right();
664 }
665 }
666 TreeChunk* tc = TreeChunk::as_TreeChunk(fc);
667 // This chunk is being returned to the binary try. It's embedded
668 // TreeList should be unused at this point.
669 tc->initialize();
670 if (curTL != NULL) { // exact match
671 tc->set_list(curTL);
672 curTL->returnChunkAtTail(tc);
673 } else { // need a new node in tree
674 tc->clearNext();
675 tc->linkPrev(NULL);
676 TreeList* newTL = TreeList::as_TreeList(tc);
677 assert(((TreeChunk*)tc)->list() == newTL,
678 "List was not initialized correctly");
679 if (prevTL == NULL) { // we are the only tree node
680 assert(root() == NULL, "control point invariant");
681 set_root(newTL);
682 } else { // insert under prevTL ...
683 if (prevTL->size() < size) { // am right child
684 assert(prevTL->right() == NULL, "control point invariant");
685 prevTL->setRight(newTL);
686 } else { // am left child
687 assert(prevTL->size() > size && prevTL->left() == NULL, "cpt pt inv");
688 prevTL->setLeft(newTL);
689 }
690 }
691 }
692 assert(tc->list() != NULL, "Tree list should be set");
694 inc_totalSize(size);
695 // Method 'totalSizeInTree' walks through the every block in the
696 // tree, so it can cause significant performance loss if there are
697 // many blocks in the tree
698 assert(!FLSVerifyDictionary || totalSizeInTree(root()) == totalSize(), "_totalSize inconsistency");
699 set_totalFreeBlocks(totalFreeBlocks() + 1);
700 if (FLSVerifyDictionary) {
701 verifyTree();
702 }
703 }
705 size_t BinaryTreeDictionary::maxChunkSize() const {
706 verify_par_locked();
707 TreeList* tc = root();
708 if (tc == NULL) return 0;
709 for (; tc->right() != NULL; tc = tc->right());
710 return tc->size();
711 }
713 size_t BinaryTreeDictionary::totalListLength(TreeList* tl) const {
714 size_t res;
715 res = tl->count();
716 #ifdef ASSERT
717 size_t cnt;
718 FreeChunk* tc = tl->head();
719 for (cnt = 0; tc != NULL; tc = tc->next(), cnt++);
720 assert(res == cnt, "The count is not being maintained correctly");
721 #endif
722 return res;
723 }
725 size_t BinaryTreeDictionary::totalSizeInTree(TreeList* tl) const {
726 if (tl == NULL)
727 return 0;
728 return (tl->size() * totalListLength(tl)) +
729 totalSizeInTree(tl->left()) +
730 totalSizeInTree(tl->right());
731 }
733 double BinaryTreeDictionary::sum_of_squared_block_sizes(TreeList* const tl) const {
734 if (tl == NULL) {
735 return 0.0;
736 }
737 double size = (double)(tl->size());
738 double curr = size * size * totalListLength(tl);
739 curr += sum_of_squared_block_sizes(tl->left());
740 curr += sum_of_squared_block_sizes(tl->right());
741 return curr;
742 }
744 size_t BinaryTreeDictionary::totalFreeBlocksInTree(TreeList* tl) const {
745 if (tl == NULL)
746 return 0;
747 return totalListLength(tl) +
748 totalFreeBlocksInTree(tl->left()) +
749 totalFreeBlocksInTree(tl->right());
750 }
752 size_t BinaryTreeDictionary::numFreeBlocks() const {
753 assert(totalFreeBlocksInTree(root()) == totalFreeBlocks(),
754 "_totalFreeBlocks inconsistency");
755 return totalFreeBlocks();
756 }
758 size_t BinaryTreeDictionary::treeHeightHelper(TreeList* tl) const {
759 if (tl == NULL)
760 return 0;
761 return 1 + MAX2(treeHeightHelper(tl->left()),
762 treeHeightHelper(tl->right()));
763 }
765 size_t BinaryTreeDictionary::treeHeight() const {
766 return treeHeightHelper(root());
767 }
769 size_t BinaryTreeDictionary::totalNodesHelper(TreeList* tl) const {
770 if (tl == NULL) {
771 return 0;
772 }
773 return 1 + totalNodesHelper(tl->left()) +
774 totalNodesHelper(tl->right());
775 }
777 size_t BinaryTreeDictionary::totalNodesInTree(TreeList* tl) const {
778 return totalNodesHelper(root());
779 }
781 void BinaryTreeDictionary::dictCensusUpdate(size_t size, bool split, bool birth){
782 TreeList* nd = findList(size);
783 if (nd) {
784 if (split) {
785 if (birth) {
786 nd->increment_splitBirths();
787 nd->increment_surplus();
788 } else {
789 nd->increment_splitDeaths();
790 nd->decrement_surplus();
791 }
792 } else {
793 if (birth) {
794 nd->increment_coalBirths();
795 nd->increment_surplus();
796 } else {
797 nd->increment_coalDeaths();
798 nd->decrement_surplus();
799 }
800 }
801 }
802 // A list for this size may not be found (nd == 0) if
803 // This is a death where the appropriate list is now
804 // empty and has been removed from the list.
805 // This is a birth associated with a LinAB. The chunk
806 // for the LinAB is not in the dictionary.
807 }
809 bool BinaryTreeDictionary::coalDictOverPopulated(size_t size) {
810 TreeList* list_of_size = findList(size);
811 // None of requested size implies overpopulated.
812 return list_of_size == NULL || list_of_size->coalDesired() <= 0 ||
813 list_of_size->count() > list_of_size->coalDesired();
814 }
816 // Closures for walking the binary tree.
817 // do_list() walks the free list in a node applying the closure
818 // to each free chunk in the list
819 // do_tree() walks the nodes in the binary tree applying do_list()
820 // to each list at each node.
822 class TreeCensusClosure : public StackObj {
823 protected:
824 virtual void do_list(FreeList* fl) = 0;
825 public:
826 virtual void do_tree(TreeList* tl) = 0;
827 };
829 class AscendTreeCensusClosure : public TreeCensusClosure {
830 public:
831 void do_tree(TreeList* tl) {
832 if (tl != NULL) {
833 do_tree(tl->left());
834 do_list(tl);
835 do_tree(tl->right());
836 }
837 }
838 };
840 class DescendTreeCensusClosure : public TreeCensusClosure {
841 public:
842 void do_tree(TreeList* tl) {
843 if (tl != NULL) {
844 do_tree(tl->right());
845 do_list(tl);
846 do_tree(tl->left());
847 }
848 }
849 };
851 // For each list in the tree, calculate the desired, desired
852 // coalesce, count before sweep, and surplus before sweep.
853 class BeginSweepClosure : public AscendTreeCensusClosure {
854 double _percentage;
855 float _inter_sweep_current;
856 float _inter_sweep_estimate;
858 public:
859 BeginSweepClosure(double p, float inter_sweep_current,
860 float inter_sweep_estimate) :
861 _percentage(p),
862 _inter_sweep_current(inter_sweep_current),
863 _inter_sweep_estimate(inter_sweep_estimate) { }
865 void do_list(FreeList* fl) {
866 double coalSurplusPercent = _percentage;
867 fl->compute_desired(_inter_sweep_current, _inter_sweep_estimate);
868 fl->set_coalDesired((ssize_t)((double)fl->desired() * coalSurplusPercent));
869 fl->set_beforeSweep(fl->count());
870 fl->set_bfrSurp(fl->surplus());
871 }
872 };
874 // Used to search the tree until a condition is met.
875 // Similar to TreeCensusClosure but searches the
876 // tree and returns promptly when found.
878 class TreeSearchClosure : public StackObj {
879 protected:
880 virtual bool do_list(FreeList* fl) = 0;
881 public:
882 virtual bool do_tree(TreeList* tl) = 0;
883 };
885 #if 0 // Don't need this yet but here for symmetry.
886 class AscendTreeSearchClosure : public TreeSearchClosure {
887 public:
888 bool do_tree(TreeList* tl) {
889 if (tl != NULL) {
890 if (do_tree(tl->left())) return true;
891 if (do_list(tl)) return true;
892 if (do_tree(tl->right())) return true;
893 }
894 return false;
895 }
896 };
897 #endif
899 class DescendTreeSearchClosure : public TreeSearchClosure {
900 public:
901 bool do_tree(TreeList* tl) {
902 if (tl != NULL) {
903 if (do_tree(tl->right())) return true;
904 if (do_list(tl)) return true;
905 if (do_tree(tl->left())) return true;
906 }
907 return false;
908 }
909 };
911 // Searches the tree for a chunk that ends at the
912 // specified address.
913 class EndTreeSearchClosure : public DescendTreeSearchClosure {
914 HeapWord* _target;
915 FreeChunk* _found;
917 public:
918 EndTreeSearchClosure(HeapWord* target) : _target(target), _found(NULL) {}
919 bool do_list(FreeList* fl) {
920 FreeChunk* item = fl->head();
921 while (item != NULL) {
922 if (item->end() == _target) {
923 _found = item;
924 return true;
925 }
926 item = item->next();
927 }
928 return false;
929 }
930 FreeChunk* found() { return _found; }
931 };
933 FreeChunk* BinaryTreeDictionary::find_chunk_ends_at(HeapWord* target) const {
934 EndTreeSearchClosure etsc(target);
935 bool found_target = etsc.do_tree(root());
936 assert(found_target || etsc.found() == NULL, "Consistency check");
937 assert(!found_target || etsc.found() != NULL, "Consistency check");
938 return etsc.found();
939 }
941 void BinaryTreeDictionary::beginSweepDictCensus(double coalSurplusPercent,
942 float inter_sweep_current, float inter_sweep_estimate) {
943 BeginSweepClosure bsc(coalSurplusPercent, inter_sweep_current,
944 inter_sweep_estimate);
945 bsc.do_tree(root());
946 }
948 // Closures and methods for calculating total bytes returned to the
949 // free lists in the tree.
950 NOT_PRODUCT(
951 class InitializeDictReturnedBytesClosure : public AscendTreeCensusClosure {
952 public:
953 void do_list(FreeList* fl) {
954 fl->set_returnedBytes(0);
955 }
956 };
958 void BinaryTreeDictionary::initializeDictReturnedBytes() {
959 InitializeDictReturnedBytesClosure idrb;
960 idrb.do_tree(root());
961 }
963 class ReturnedBytesClosure : public AscendTreeCensusClosure {
964 size_t _dictReturnedBytes;
965 public:
966 ReturnedBytesClosure() { _dictReturnedBytes = 0; }
967 void do_list(FreeList* fl) {
968 _dictReturnedBytes += fl->returnedBytes();
969 }
970 size_t dictReturnedBytes() { return _dictReturnedBytes; }
971 };
973 size_t BinaryTreeDictionary::sumDictReturnedBytes() {
974 ReturnedBytesClosure rbc;
975 rbc.do_tree(root());
977 return rbc.dictReturnedBytes();
978 }
980 // Count the number of entries in the tree.
981 class treeCountClosure : public DescendTreeCensusClosure {
982 public:
983 uint count;
984 treeCountClosure(uint c) { count = c; }
985 void do_list(FreeList* fl) {
986 count++;
987 }
988 };
990 size_t BinaryTreeDictionary::totalCount() {
991 treeCountClosure ctc(0);
992 ctc.do_tree(root());
993 return ctc.count;
994 }
995 )
997 // Calculate surpluses for the lists in the tree.
998 class setTreeSurplusClosure : public AscendTreeCensusClosure {
999 double percentage;
1000 public:
1001 setTreeSurplusClosure(double v) { percentage = v; }
1002 void do_list(FreeList* fl) {
1003 double splitSurplusPercent = percentage;
1004 fl->set_surplus(fl->count() -
1005 (ssize_t)((double)fl->desired() * splitSurplusPercent));
1006 }
1007 };
1009 void BinaryTreeDictionary::setTreeSurplus(double splitSurplusPercent) {
1010 setTreeSurplusClosure sts(splitSurplusPercent);
1011 sts.do_tree(root());
1012 }
1014 // Set hints for the lists in the tree.
1015 class setTreeHintsClosure : public DescendTreeCensusClosure {
1016 size_t hint;
1017 public:
1018 setTreeHintsClosure(size_t v) { hint = v; }
1019 void do_list(FreeList* fl) {
1020 fl->set_hint(hint);
1021 assert(fl->hint() == 0 || fl->hint() > fl->size(),
1022 "Current hint is inconsistent");
1023 if (fl->surplus() > 0) {
1024 hint = fl->size();
1025 }
1026 }
1027 };
1029 void BinaryTreeDictionary::setTreeHints(void) {
1030 setTreeHintsClosure sth(0);
1031 sth.do_tree(root());
1032 }
1034 // Save count before previous sweep and splits and coalesces.
1035 class clearTreeCensusClosure : public AscendTreeCensusClosure {
1036 void do_list(FreeList* fl) {
1037 fl->set_prevSweep(fl->count());
1038 fl->set_coalBirths(0);
1039 fl->set_coalDeaths(0);
1040 fl->set_splitBirths(0);
1041 fl->set_splitDeaths(0);
1042 }
1043 };
1045 void BinaryTreeDictionary::clearTreeCensus(void) {
1046 clearTreeCensusClosure ctc;
1047 ctc.do_tree(root());
1048 }
1050 // Do reporting and post sweep clean up.
1051 void BinaryTreeDictionary::endSweepDictCensus(double splitSurplusPercent) {
1052 // Does walking the tree 3 times hurt?
1053 setTreeSurplus(splitSurplusPercent);
1054 setTreeHints();
1055 if (PrintGC && Verbose) {
1056 reportStatistics();
1057 }
1058 clearTreeCensus();
1059 }
1061 // Print summary statistics
1062 void BinaryTreeDictionary::reportStatistics() const {
1063 verify_par_locked();
1064 gclog_or_tty->print("Statistics for BinaryTreeDictionary:\n"
1065 "------------------------------------\n");
1066 size_t totalSize = totalChunkSize(debug_only(NULL));
1067 size_t freeBlocks = numFreeBlocks();
1068 gclog_or_tty->print("Total Free Space: %d\n", totalSize);
1069 gclog_or_tty->print("Max Chunk Size: %d\n", maxChunkSize());
1070 gclog_or_tty->print("Number of Blocks: %d\n", freeBlocks);
1071 if (freeBlocks > 0) {
1072 gclog_or_tty->print("Av. Block Size: %d\n", totalSize/freeBlocks);
1073 }
1074 gclog_or_tty->print("Tree Height: %d\n", treeHeight());
1075 }
1077 // Print census information - counts, births, deaths, etc.
1078 // for each list in the tree. Also print some summary
1079 // information.
1080 class printTreeCensusClosure : public AscendTreeCensusClosure {
1081 int _print_line;
1082 size_t _totalFree;
1083 FreeList _total;
1085 public:
1086 printTreeCensusClosure() {
1087 _print_line = 0;
1088 _totalFree = 0;
1089 }
1090 FreeList* total() { return &_total; }
1091 size_t totalFree() { return _totalFree; }
1092 void do_list(FreeList* fl) {
1093 if (++_print_line >= 40) {
1094 FreeList::print_labels_on(gclog_or_tty, "size");
1095 _print_line = 0;
1096 }
1097 fl->print_on(gclog_or_tty);
1098 _totalFree += fl->count() * fl->size() ;
1099 total()->set_count( total()->count() + fl->count() );
1100 total()->set_bfrSurp( total()->bfrSurp() + fl->bfrSurp() );
1101 total()->set_surplus( total()->splitDeaths() + fl->surplus() );
1102 total()->set_desired( total()->desired() + fl->desired() );
1103 total()->set_prevSweep( total()->prevSweep() + fl->prevSweep() );
1104 total()->set_beforeSweep(total()->beforeSweep() + fl->beforeSweep());
1105 total()->set_coalBirths( total()->coalBirths() + fl->coalBirths() );
1106 total()->set_coalDeaths( total()->coalDeaths() + fl->coalDeaths() );
1107 total()->set_splitBirths(total()->splitBirths() + fl->splitBirths());
1108 total()->set_splitDeaths(total()->splitDeaths() + fl->splitDeaths());
1109 }
1110 };
1112 void BinaryTreeDictionary::printDictCensus(void) const {
1114 gclog_or_tty->print("\nBinaryTree\n");
1115 FreeList::print_labels_on(gclog_or_tty, "size");
1116 printTreeCensusClosure ptc;
1117 ptc.do_tree(root());
1119 FreeList* total = ptc.total();
1120 FreeList::print_labels_on(gclog_or_tty, " ");
1121 total->print_on(gclog_or_tty, "TOTAL\t");
1122 gclog_or_tty->print(
1123 "totalFree(words): " SIZE_FORMAT_W(16)
1124 " growth: %8.5f deficit: %8.5f\n",
1125 ptc.totalFree(),
1126 (double)(total->splitBirths() + total->coalBirths()
1127 - total->splitDeaths() - total->coalDeaths())
1128 /(total->prevSweep() != 0 ? (double)total->prevSweep() : 1.0),
1129 (double)(total->desired() - total->count())
1130 /(total->desired() != 0 ? (double)total->desired() : 1.0));
1131 }
1133 // Verify the following tree invariants:
1134 // . _root has no parent
1135 // . parent and child point to each other
1136 // . each node's key correctly related to that of its child(ren)
1137 void BinaryTreeDictionary::verifyTree() const {
1138 guarantee(root() == NULL || totalFreeBlocks() == 0 ||
1139 totalSize() != 0, "_totalSize should't be 0?");
1140 guarantee(root() == NULL || root()->parent() == NULL, "_root shouldn't have parent");
1141 verifyTreeHelper(root());
1142 }
1144 size_t BinaryTreeDictionary::verifyPrevFreePtrs(TreeList* tl) {
1145 size_t ct = 0;
1146 for (FreeChunk* curFC = tl->head(); curFC != NULL; curFC = curFC->next()) {
1147 ct++;
1148 assert(curFC->prev() == NULL || curFC->prev()->isFree(),
1149 "Chunk should be free");
1150 }
1151 return ct;
1152 }
1154 // Note: this helper is recursive rather than iterative, so use with
1155 // caution on very deep trees; and watch out for stack overflow errors;
1156 // In general, to be used only for debugging.
1157 void BinaryTreeDictionary::verifyTreeHelper(TreeList* tl) const {
1158 if (tl == NULL)
1159 return;
1160 guarantee(tl->size() != 0, "A list must has a size");
1161 guarantee(tl->left() == NULL || tl->left()->parent() == tl,
1162 "parent<-/->left");
1163 guarantee(tl->right() == NULL || tl->right()->parent() == tl,
1164 "parent<-/->right");;
1165 guarantee(tl->left() == NULL || tl->left()->size() < tl->size(),
1166 "parent !> left");
1167 guarantee(tl->right() == NULL || tl->right()->size() > tl->size(),
1168 "parent !< left");
1169 guarantee(tl->head() == NULL || tl->head()->isFree(), "!Free");
1170 guarantee(tl->head() == NULL || tl->head_as_TreeChunk()->list() == tl,
1171 "list inconsistency");
1172 guarantee(tl->count() > 0 || (tl->head() == NULL && tl->tail() == NULL),
1173 "list count is inconsistent");
1174 guarantee(tl->count() > 1 || tl->head() == tl->tail(),
1175 "list is incorrectly constructed");
1176 size_t count = verifyPrevFreePtrs(tl);
1177 guarantee(count == (size_t)tl->count(), "Node count is incorrect");
1178 if (tl->head() != NULL) {
1179 tl->head_as_TreeChunk()->verifyTreeChunkList();
1180 }
1181 verifyTreeHelper(tl->left());
1182 verifyTreeHelper(tl->right());
1183 }
1185 void BinaryTreeDictionary::verify() const {
1186 verifyTree();
1187 guarantee(totalSize() == totalSizeInTree(root()), "Total Size inconsistency");
1188 }