Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 790e66e5fbac |
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/* * Copyright 2001-2005 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. * */ // // Free block maintenance for Concurrent Mark Sweep Generation // // The main data structure for free blocks are // . an indexed array of small free blocks, and // . a dictionary of large free blocks // // No virtuals in FreeChunk (don't want any vtables). // A FreeChunk is merely a chunk that can be in a doubly linked list // and has a size field. NOTE: FreeChunks are distinguished from allocated // objects in two ways (by the sweeper). The second word (prev) has the // LSB set to indicate a free chunk; allocated objects' klass() pointers // don't have their LSB set. The corresponding bit in the CMSBitMap is // set when the chunk is allocated. There are also blocks that "look free" // but are not part of the free list and should not be coalesced into larger // free blocks. These free blocks have their two LSB's set. class FreeChunk VALUE_OBJ_CLASS_SPEC { friend class VMStructs; FreeChunk* _next; FreeChunk* _prev; size_t _size; public: NOT_PRODUCT(static const size_t header_size();) // Returns "true" if the "wrd", which is required to be the second word // of a block, indicates that the block represents a free chunk. static bool secondWordIndicatesFreeChunk(intptr_t wrd) { return (wrd & 0x1) == 0x1; } bool isFree() const { return secondWordIndicatesFreeChunk((intptr_t)_prev); } bool cantCoalesce() const { return (((intptr_t)_prev) & 0x3) == 0x3; } FreeChunk* next() const { return _next; } FreeChunk* prev() const { return (FreeChunk*)(((intptr_t)_prev) & ~(0x3)); } debug_only(void* prev_addr() const { return (void*)&_prev; }) void linkAfter(FreeChunk* ptr) { linkNext(ptr); if (ptr != NULL) ptr->linkPrev(this); } void linkAfterNonNull(FreeChunk* ptr) { assert(ptr != NULL, "precondition violation"); linkNext(ptr); ptr->linkPrev(this); } void linkNext(FreeChunk* ptr) { _next = ptr; } void linkPrev(FreeChunk* ptr) { _prev = (FreeChunk*)((intptr_t)ptr | 0x1); } void clearPrev() { _prev = NULL; } void clearNext() { _next = NULL; } void dontCoalesce() { // the block should be free assert(isFree(), "Should look like a free block"); _prev = (FreeChunk*)(((intptr_t)_prev) | 0x2); } void markFree() { _prev = (FreeChunk*)((intptr_t)_prev | 0x1); } void markNotFree() { _prev = NULL; } size_t size() const { return _size; } void setSize(size_t size) { _size = size; } // For volatile reads: size_t* size_addr() { return &_size; } // Return the address past the end of this chunk HeapWord* end() const { return ((HeapWord*) this) + _size; } // debugging void verify() const PRODUCT_RETURN; void verifyList() const PRODUCT_RETURN; void mangleAllocated(size_t size) PRODUCT_RETURN; void mangleFreed(size_t size) PRODUCT_RETURN; }; // Alignment helpers etc. #define numQuanta(x,y) ((x+y-1)/y) enum AlignmentConstants { MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment }; // A FreeBlockDictionary is an abstract superclass that will allow // a number of alternative implementations in the future. class FreeBlockDictionary: public CHeapObj { public: enum Dither { atLeast, exactly, roughly }; enum DictionaryChoice { dictionaryBinaryTree = 0, dictionarySplayTree = 1, dictionarySkipList = 2 }; private: NOT_PRODUCT(Mutex* _lock;) public: virtual void removeChunk(FreeChunk* fc) = 0; virtual FreeChunk* getChunk(size_t size, Dither dither = atLeast) = 0; virtual void returnChunk(FreeChunk* chunk) = 0; virtual size_t totalChunkSize(debug_only(const Mutex* lock)) const = 0; virtual size_t maxChunkSize() const = 0; virtual size_t minSize() const = 0; // Reset the dictionary to the initial conditions for a single // block. virtual void reset(HeapWord* addr, size_t size) = 0; virtual void reset() = 0; virtual void dictCensusUpdate(size_t size, bool split, bool birth) = 0; virtual bool coalDictOverPopulated(size_t size) = 0; virtual void beginSweepDictCensus(double coalSurplusPercent, float sweep_current, float sweep_ewstimate) = 0; virtual void endSweepDictCensus(double splitSurplusPercent) = 0; virtual FreeChunk* findLargestDict() const = 0; // verify that the given chunk is in the dictionary. virtual bool verifyChunkInFreeLists(FreeChunk* tc) const = 0; // Sigma_{all_free_blocks} (block_size^2) virtual double sum_of_squared_block_sizes() const = 0; virtual FreeChunk* find_chunk_ends_at(HeapWord* target) const = 0; virtual void inc_totalSize(size_t v) = 0; virtual void dec_totalSize(size_t v) = 0; NOT_PRODUCT ( virtual size_t sumDictReturnedBytes() = 0; virtual void initializeDictReturnedBytes() = 0; virtual size_t totalCount() = 0; ) virtual void reportStatistics() const { gclog_or_tty->print("No statistics available"); } virtual void printDictCensus() const = 0; virtual void verify() const = 0; Mutex* par_lock() const PRODUCT_RETURN0; void set_par_lock(Mutex* lock) PRODUCT_RETURN; void verify_par_locked() const PRODUCT_RETURN; };