duke@435: /*
mikael@6198:  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
jmasa@3730: #ifndef SHARE_VM_MEMORY_FREELIST_HPP
jmasa@3730: #define SHARE_VM_MEMORY_FREELIST_HPP
stefank@2314: 
stefank@2314: #include "gc_implementation/shared/allocationStats.hpp"
stefank@2314: 
duke@435: class CompactibleFreeListSpace;
duke@435: 
jmasa@3730: // A class for maintaining a free list of Chunk's.  The FreeList
duke@435: // maintains a the structure of the list (head, tail, etc.) plus
duke@435: // statistics for allocations from the list.  The links between items
duke@435: // are not part of FreeList.  The statistics are
jmasa@3730: // used to make decisions about coalescing Chunk's when they
duke@435: // are swept during collection.
duke@435: //
duke@435: // See the corresponding .cpp file for a description of the specifics
duke@435: // for that implementation.
duke@435: 
duke@435: class Mutex;
duke@435: 
jmasa@4196: template <class Chunk_t>
duke@435: class FreeList VALUE_OBJ_CLASS_SPEC {
duke@435:   friend class CompactibleFreeListSpace;
dcubed@587:   friend class VMStructs;
ysr@1580: 
ysr@1580:  private:
jmasa@4196:   Chunk_t*      _head;          // Head of list of free chunks
jmasa@4196:   Chunk_t*      _tail;          // Tail of list of free chunks
ysr@1580:   size_t        _size;          // Size in Heap words of each chunk
duke@435:   ssize_t       _count;         // Number of entries in list
duke@435: 
jmasa@4196:  protected:
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   Mutex*        _protecting_lock;
duke@435: #endif
duke@435: 
duke@435:   // Asserts false if the protecting lock (if any) is not held.
duke@435:   void assert_proper_lock_protection_work() const PRODUCT_RETURN;
duke@435:   void assert_proper_lock_protection() const {
duke@435: #ifdef ASSERT
duke@435:     if (_protecting_lock != NULL)
duke@435:       assert_proper_lock_protection_work();
duke@435: #endif
duke@435:   }
duke@435: 
ysr@1580:   void increment_count()    {
ysr@1580:     _count++;
ysr@1580:   }
ysr@1580: 
duke@435:   void decrement_count() {
duke@435:     _count--;
ysr@447:     assert(_count >= 0, "Count should not be negative");
ysr@447:   }
duke@435: 
duke@435:  public:
duke@435:   // Constructor
duke@435:   // Construct a list without any entries.
duke@435:   FreeList();
duke@435: 
jmasa@4196:   // Do initialization
jmasa@4196:   void initialize();
jmasa@4196: 
jmasa@4196:   // Reset the head, tail, and count of a free list.
jmasa@4196:   void reset();
duke@435: 
duke@435:   // Declare the current free list to be protected by the given lock.
duke@435: #ifdef ASSERT
jmasa@4196:   Mutex* protecting_lock() const { return _protecting_lock; }
jmasa@4196:   void set_protecting_lock(Mutex* v) {
jmasa@4196:     _protecting_lock = v;
duke@435:   }
duke@435: #endif
duke@435: 
duke@435:   // Accessors.
jmasa@4196:   Chunk_t* head() const {
duke@435:     assert_proper_lock_protection();
duke@435:     return _head;
duke@435:   }
jmasa@4196:   void set_head(Chunk_t* v) {
duke@435:     assert_proper_lock_protection();
duke@435:     _head = v;
duke@435:     assert(!_head || _head->size() == _size, "bad chunk size");
duke@435:   }
duke@435:   // Set the head of the list and set the prev field of non-null
duke@435:   // values to NULL.
jmasa@4196:   void link_head(Chunk_t* v);
duke@435: 
jmasa@4196:   Chunk_t* tail() const {
duke@435:     assert_proper_lock_protection();
duke@435:     return _tail;
duke@435:   }
jmasa@4196:   void set_tail(Chunk_t* v) {
duke@435:     assert_proper_lock_protection();
duke@435:     _tail = v;
duke@435:     assert(!_tail || _tail->size() == _size, "bad chunk size");
duke@435:   }
duke@435:   // Set the tail of the list and set the next field of non-null
duke@435:   // values to NULL.
jmasa@4196:   void link_tail(Chunk_t* v) {
duke@435:     assert_proper_lock_protection();
duke@435:     set_tail(v);
duke@435:     if (v != NULL) {
jmasa@3732:       v->clear_next();
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   // No locking checks in read-accessors: lock-free reads (only) are benign.
duke@435:   // Readers are expected to have the lock if they are doing work that
duke@435:   // requires atomicity guarantees in sections of code.
duke@435:   size_t size() const {
duke@435:     return _size;
duke@435:   }
duke@435:   void set_size(size_t v) {
duke@435:     assert_proper_lock_protection();
duke@435:     _size = v;
duke@435:   }
jmasa@4196:   ssize_t count() const { return _count; }
jmasa@4196:   void set_count(ssize_t v) { _count = v;}
duke@435: 
jmasa@4196:   size_t get_better_size() { return size(); }
duke@435: 
jmasa@4196:   size_t returned_bytes() const { ShouldNotReachHere(); return 0; }
jmasa@4196:   void set_returned_bytes(size_t v) {}
jmasa@4196:   void increment_returned_bytes_by(size_t v) {}
duke@435: 
duke@435:   // Unlink head of list and return it.  Returns NULL if
duke@435:   // the list is empty.
jmasa@4196:   Chunk_t* get_chunk_at_head();
duke@435: 
duke@435:   // Remove the first "n" or "count", whichever is smaller, chunks from the
duke@435:   // list, setting "fl", which is required to be empty, to point to them.
jmasa@4196:   void getFirstNChunksFromList(size_t n, FreeList<Chunk_t>* fl);
duke@435: 
duke@435:   // Unlink this chunk from it's free list
jmasa@4196:   void remove_chunk(Chunk_t* fc);
duke@435: 
duke@435:   // Add this chunk to this free list.
jmasa@4196:   void return_chunk_at_head(Chunk_t* fc);
jmasa@4196:   void return_chunk_at_tail(Chunk_t* fc);
duke@435: 
duke@435:   // Similar to returnChunk* but also records some diagnostic
duke@435:   // information.
jmasa@4196:   void return_chunk_at_head(Chunk_t* fc, bool record_return);
jmasa@4196:   void return_chunk_at_tail(Chunk_t* fc, bool record_return);
duke@435: 
duke@435:   // Prepend "fl" (whose size is required to be the same as that of "this")
duke@435:   // to the front of "this" list.
jmasa@4196:   void prepend(FreeList<Chunk_t>* fl);
duke@435: 
duke@435:   // Verify that the chunk is in the list.
duke@435:   // found.  Return NULL if "fc" is not found.
jmasa@4196:   bool verify_chunk_in_free_list(Chunk_t* fc) const;
ysr@447: 
ysr@447:   // Printing support
ysr@447:   static void print_labels_on(outputStream* st, const char* c);
ysr@447:   void print_on(outputStream* st, const char* c = NULL) const;
duke@435: };
stefank@2314: 
jmasa@3730: #endif // SHARE_VM_MEMORY_FREELIST_HPP