hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/freeList.cpp - platform/libcore - Git at Google

 /*
  * Copyright 2001-2006 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */

 # include "incls/_precompiled.incl"
 # include "incls/_freeList.cpp.incl"

 // Free list.  A FreeList is used to access a linked list of chunks
 // of space in the heap.  The head and tail are maintained so that
 // items can be (as in the current implementation) added at the
 // at the tail of the list and removed from the head of the list to
 // maintain a FIFO queue.

 FreeList::FreeList() :
   _head(NULL), _tail(NULL)
 #ifdef ASSERT
   , _protecting_lock(NULL)
 #endif
 {
   _size         = 0;
   _count        = 0;
   _hint         = 0;
   init_statistics();
 }

 FreeList::FreeList(FreeChunk* fc) :
   _head(fc), _tail(fc)
 #ifdef ASSERT
   , _protecting_lock(NULL)
 #endif
 {
   _size         = fc->size();
   _count        = 1;
   _hint         = 0;
   init_statistics();
 #ifndef PRODUCT
   _allocation_stats.set_returnedBytes(size() * HeapWordSize);
 #endif
 }

 FreeList::FreeList(HeapWord* addr, size_t size) :
   _head((FreeChunk*) addr), _tail((FreeChunk*) addr)
 #ifdef ASSERT
   , _protecting_lock(NULL)
 #endif
 {
   assert(size > sizeof(FreeChunk), "size is too small");
   head()->setSize(size);
   _size         = size;
   _count        = 1;
   init_statistics();
 #ifndef PRODUCT
   _allocation_stats.set_returnedBytes(_size * HeapWordSize);
 #endif
 }

 void FreeList::reset(size_t hint) {
   set_count(0);
   set_head(NULL);
   set_tail(NULL);
   set_hint(hint);
 }

 void FreeList::init_statistics() {
   _allocation_stats.initialize();
 }

 FreeChunk* FreeList::getChunkAtHead() {
   assert_proper_lock_protection();
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
   FreeChunk* fc = head();
   if (fc != NULL) {
     FreeChunk* nextFC = fc->next();
     if (nextFC != NULL) {
       // The chunk fc being removed has a "next".  Set the "next" to the
       // "prev" of fc.
       nextFC->linkPrev(NULL);
     } else { // removed tail of list
       link_tail(NULL);
     }
     link_head(nextFC);
     decrement_count();
   }
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
   return fc;
 }


 void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
   assert_proper_lock_protection();
   assert(fl->count() == 0, "Precondition");
   if (count() > 0) {
     int k = 1;
     fl->set_head(head()); n--;
     FreeChunk* tl = head();
     while (tl->next() != NULL && n > 0) {
       tl = tl->next(); n--; k++;
     }
     assert(tl != NULL, "Loop Inv.");

     // First, fix up the list we took from.
     FreeChunk* new_head = tl->next();
     set_head(new_head);
     set_count(count() - k);
     if (new_head == NULL) {
       set_tail(NULL);
     } else {
       new_head->linkPrev(NULL);
     }
     // Now we can fix up the tail.
     tl->linkNext(NULL);
     // And return the result.
     fl->set_tail(tl);
     fl->set_count(k);
   }
 }

 // Remove this chunk from the list
 void FreeList::removeChunk(FreeChunk*fc) {
    assert_proper_lock_protection();
    assert(head() != NULL, "Remove from empty list");
    assert(fc != NULL, "Remove a NULL chunk");
    assert(size() == fc->size(), "Wrong list");
    assert(head() == NULL || head()->prev() == NULL, "list invariant");
    assert(tail() == NULL || tail()->next() == NULL, "list invariant");

    FreeChunk* prevFC = fc->prev();
    FreeChunk* nextFC = fc->next();
    if (nextFC != NULL) {
      // The chunk fc being removed has a "next".  Set the "next" to the
      // "prev" of fc.
      nextFC->linkPrev(prevFC);
    } else { // removed tail of list
      link_tail(prevFC);
    }
    if (prevFC == NULL) { // removed head of list
      link_head(nextFC);
      assert(nextFC == NULL || nextFC->prev() == NULL,
        "Prev of head should be NULL");
    } else {
      prevFC->linkNext(nextFC);
      assert(tail() != prevFC || prevFC->next() == NULL,
        "Next of tail should be NULL");
    }
    decrement_count();
 #define TRAP_CODE 1
 #if TRAP_CODE
    if (head() == NULL) {
      guarantee(tail() == NULL, "INVARIANT");
      guarantee(count() == 0, "INVARIANT");
    }
 #endif
    // clear next and prev fields of fc, debug only
    NOT_PRODUCT(
      fc->linkPrev(NULL);
      fc->linkNext(NULL);
    )
    assert(fc->isFree(), "Should still be a free chunk");
    assert(head() == NULL || head()->prev() == NULL, "list invariant");
    assert(tail() == NULL || tail()->next() == NULL, "list invariant");
    assert(head() == NULL || head()->size() == size(), "wrong item on list");
    assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
 }

 // Add this chunk at the head of the list.
 void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
   assert_proper_lock_protection();
   assert(chunk != NULL, "insert a NULL chunk");
   assert(size() == chunk->size(), "Wrong size");
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");

   FreeChunk* oldHead = head();
   assert(chunk != oldHead, "double insertion");
   chunk->linkAfter(oldHead);
   link_head(chunk);
   if (oldHead == NULL) { // only chunk in list
     assert(tail() == NULL, "inconsistent FreeList");
     link_tail(chunk);
   }
   increment_count(); // of # of chunks in list
   DEBUG_ONLY(
     if (record_return) {
       increment_returnedBytes_by(size()*HeapWordSize);
     }
   )
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
   assert(head() == NULL || head()->size() == size(), "wrong item on list");
   assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
 }

 void FreeList::returnChunkAtHead(FreeChunk* chunk) {
   assert_proper_lock_protection();
   returnChunkAtHead(chunk, true);
 }

 // Add this chunk at the tail of the list.
 void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
   assert_proper_lock_protection();
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
   assert(chunk != NULL, "insert a NULL chunk");
   assert(size() == chunk->size(), "wrong size");

   FreeChunk* oldTail = tail();
   assert(chunk != oldTail, "double insertion");
   if (oldTail != NULL) {
     oldTail->linkAfter(chunk);
   } else { // only chunk in list
     assert(head() == NULL, "inconsistent FreeList");
     link_head(chunk);
   }
   link_tail(chunk);
   increment_count();  // of # of chunks in list
   DEBUG_ONLY(
     if (record_return) {
       increment_returnedBytes_by(size()*HeapWordSize);
     }
   )
   assert(head() == NULL || head()->prev() == NULL, "list invariant");
   assert(tail() == NULL || tail()->next() == NULL, "list invariant");
   assert(head() == NULL || head()->size() == size(), "wrong item on list");
   assert(tail() == NULL || tail()->size() == size(), "wrong item on list");
 }

 void FreeList::returnChunkAtTail(FreeChunk* chunk) {
   returnChunkAtTail(chunk, true);
 }

 void FreeList::prepend(FreeList* fl) {
   assert_proper_lock_protection();
   if (fl->count() > 0) {
     if (count() == 0) {
       set_head(fl->head());
       set_tail(fl->tail());
       set_count(fl->count());
     } else {
       // Both are non-empty.
       FreeChunk* fl_tail = fl->tail();
       FreeChunk* this_head = head();
       assert(fl_tail->next() == NULL, "Well-formedness of fl");
       fl_tail->linkNext(this_head);
       this_head->linkPrev(fl_tail);
       set_head(fl->head());
       set_count(count() + fl->count());
     }
     fl->set_head(NULL);
     fl->set_tail(NULL);
     fl->set_count(0);
   }
 }

 // verifyChunkInFreeLists() is used to verify that an item is in this free list.
 // It is used as a debugging aid.
 bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
   // This is an internal consistency check, not part of the check that the
   // chunk is in the free lists.
   guarantee(fc->size() == size(), "Wrong list is being searched");
   FreeChunk* curFC = head();
   while (curFC) {
     // This is an internal consistency check.
     guarantee(size() == curFC->size(), "Chunk is in wrong list.");
     if (fc == curFC) {
       return true;
     }
     curFC = curFC->next();
   }
   return false;
 }

 #ifndef PRODUCT
 void FreeList::assert_proper_lock_protection_work() const {
 #ifdef ASSERT
   if (_protecting_lock != NULL &&
       SharedHeap::heap()->n_par_threads() > 0) {
     // Should become an assert.
     guarantee(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
   }
 #endif
 }
 #endif
	/*
	* Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
	* CA 95054 USA or visit www.sun.com if you need additional information or
	* have any questions.
	*
	*/

	# include "incls/_precompiled.incl"
	# include "incls/_freeList.cpp.incl"

	// Free list. A FreeList is used to access a linked list of chunks
	// of space in the heap. The head and tail are maintained so that
	// items can be (as in the current implementation) added at the
	// at the tail of the list and removed from the head of the list to
	// maintain a FIFO queue.

	FreeList::FreeList() :
	_head(NULL), _tail(NULL)
	#ifdef ASSERT
	, _protecting_lock(NULL)
	#endif
	{
	_size = 0;
	_count = 0;
	_hint = 0;
	init_statistics();
	}

	FreeList::FreeList(FreeChunk* fc) :
	_head(fc), _tail(fc)
	#ifdef ASSERT
	, _protecting_lock(NULL)
	#endif
	{
	_size = fc->size();
	_count = 1;
	_hint = 0;
	init_statistics();
	#ifndef PRODUCT
	_allocation_stats.set_returnedBytes(size() * HeapWordSize);
	#endif
	}

	FreeList::FreeList(HeapWord* addr, size_t size) :
	_head((FreeChunk) addr), _tail((FreeChunk) addr)
	#ifdef ASSERT
	, _protecting_lock(NULL)
	#endif
	{
	assert(size > sizeof(FreeChunk), "size is too small");
	head()->setSize(size);
	_size = size;
	_count = 1;
	init_statistics();
	#ifndef PRODUCT
	_allocation_stats.set_returnedBytes(_size * HeapWordSize);
	#endif
	}

	void FreeList::reset(size_t hint) {
	set_count(0);
	set_head(NULL);
	set_tail(NULL);
	set_hint(hint);
	}

	void FreeList::init_statistics() {
	_allocation_stats.initialize();
	}

	FreeChunk* FreeList::getChunkAtHead() {
	assert_proper_lock_protection();
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	FreeChunk* fc = head();
	if (fc != NULL) {
	FreeChunk* nextFC = fc->next();
	if (nextFC != NULL) {
	// The chunk fc being removed has a "next". Set the "next" to the
	// "prev" of fc.
	nextFC->linkPrev(NULL);
	} else { // removed tail of list
	link_tail(NULL);
	}
	link_head(nextFC);
	decrement_count();
	}
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	return fc;
	}


	void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) {
	assert_proper_lock_protection();
	assert(fl->count() == 0, "Precondition");
	if (count() > 0) {
	int k = 1;
	fl->set_head(head()); n--;
	FreeChunk* tl = head();
	while (tl->next() != NULL && n > 0) {
	tl = tl->next(); n--; k++;
	}
	assert(tl != NULL, "Loop Inv.");

	// First, fix up the list we took from.
	FreeChunk* new_head = tl->next();
	set_head(new_head);
	set_count(count() - k);
	if (new_head == NULL) {
	set_tail(NULL);
	} else {
	new_head->linkPrev(NULL);
	}
	// Now we can fix up the tail.
	tl->linkNext(NULL);
	// And return the result.
	fl->set_tail(tl);
	fl->set_count(k);
	}
	}

	// Remove this chunk from the list
	void FreeList::removeChunk(FreeChunk*fc) {
	assert_proper_lock_protection();
	assert(head() != NULL, "Remove from empty list");
	assert(fc != NULL, "Remove a NULL chunk");
	assert(size() == fc->size(), "Wrong list");
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");

	FreeChunk* prevFC = fc->prev();
	FreeChunk* nextFC = fc->next();
	if (nextFC != NULL) {
	// The chunk fc being removed has a "next". Set the "next" to the
	// "prev" of fc.
	nextFC->linkPrev(prevFC);
	} else { // removed tail of list
	link_tail(prevFC);
	}
	if (prevFC == NULL) { // removed head of list
	link_head(nextFC);
	assert(nextFC == NULL \|\| nextFC->prev() == NULL,
	"Prev of head should be NULL");
	} else {
	prevFC->linkNext(nextFC);
	assert(tail() != prevFC \|\| prevFC->next() == NULL,
	"Next of tail should be NULL");
	}
	decrement_count();
	#define TRAP_CODE 1
	#if TRAP_CODE
	if (head() == NULL) {
	guarantee(tail() == NULL, "INVARIANT");
	guarantee(count() == 0, "INVARIANT");
	}
	#endif
	// clear next and prev fields of fc, debug only
	NOT_PRODUCT(
	fc->linkPrev(NULL);
	fc->linkNext(NULL);
	)
	assert(fc->isFree(), "Should still be a free chunk");
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	assert(head() == NULL \|\| head()->size() == size(), "wrong item on list");
	assert(tail() == NULL \|\| tail()->size() == size(), "wrong item on list");
	}

	// Add this chunk at the head of the list.
	void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) {
	assert_proper_lock_protection();
	assert(chunk != NULL, "insert a NULL chunk");
	assert(size() == chunk->size(), "Wrong size");
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");

	FreeChunk* oldHead = head();
	assert(chunk != oldHead, "double insertion");
	chunk->linkAfter(oldHead);
	link_head(chunk);
	if (oldHead == NULL) { // only chunk in list
	assert(tail() == NULL, "inconsistent FreeList");
	link_tail(chunk);
	}
	increment_count(); // of # of chunks in list
	DEBUG_ONLY(
	if (record_return) {
	increment_returnedBytes_by(size()*HeapWordSize);
	}
	)
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	assert(head() == NULL \|\| head()->size() == size(), "wrong item on list");
	assert(tail() == NULL \|\| tail()->size() == size(), "wrong item on list");
	}

	void FreeList::returnChunkAtHead(FreeChunk* chunk) {
	assert_proper_lock_protection();
	returnChunkAtHead(chunk, true);
	}

	// Add this chunk at the tail of the list.
	void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) {
	assert_proper_lock_protection();
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	assert(chunk != NULL, "insert a NULL chunk");
	assert(size() == chunk->size(), "wrong size");

	FreeChunk* oldTail = tail();
	assert(chunk != oldTail, "double insertion");
	if (oldTail != NULL) {
	oldTail->linkAfter(chunk);
	} else { // only chunk in list
	assert(head() == NULL, "inconsistent FreeList");
	link_head(chunk);
	}
	link_tail(chunk);
	increment_count(); // of # of chunks in list
	DEBUG_ONLY(
	if (record_return) {
	increment_returnedBytes_by(size()*HeapWordSize);
	}
	)
	assert(head() == NULL \|\| head()->prev() == NULL, "list invariant");
	assert(tail() == NULL \|\| tail()->next() == NULL, "list invariant");
	assert(head() == NULL \|\| head()->size() == size(), "wrong item on list");
	assert(tail() == NULL \|\| tail()->size() == size(), "wrong item on list");
	}

	void FreeList::returnChunkAtTail(FreeChunk* chunk) {
	returnChunkAtTail(chunk, true);
	}

	void FreeList::prepend(FreeList* fl) {
	assert_proper_lock_protection();
	if (fl->count() > 0) {
	if (count() == 0) {
	set_head(fl->head());
	set_tail(fl->tail());
	set_count(fl->count());
	} else {
	// Both are non-empty.
	FreeChunk* fl_tail = fl->tail();
	FreeChunk* this_head = head();
	assert(fl_tail->next() == NULL, "Well-formedness of fl");
	fl_tail->linkNext(this_head);
	this_head->linkPrev(fl_tail);
	set_head(fl->head());
	set_count(count() + fl->count());
	}
	fl->set_head(NULL);
	fl->set_tail(NULL);
	fl->set_count(0);
	}
	}

	// verifyChunkInFreeLists() is used to verify that an item is in this free list.
	// It is used as a debugging aid.
	bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const {
	// This is an internal consistency check, not part of the check that the
	// chunk is in the free lists.
	guarantee(fc->size() == size(), "Wrong list is being searched");
	FreeChunk* curFC = head();
	while (curFC) {
	// This is an internal consistency check.
	guarantee(size() == curFC->size(), "Chunk is in wrong list.");
	if (fc == curFC) {
	return true;
	}
	curFC = curFC->next();
	}
	return false;
	}

	#ifndef PRODUCT
	void FreeList::assert_proper_lock_protection_work() const {
	#ifdef ASSERT
	if (_protecting_lock != NULL &&
	SharedHeap::heap()->n_par_threads() > 0) {
	// Should become an assert.
	guarantee(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED");
	}
	#endif
	}
	#endif