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/*
* Copyright (c) 2017, 2021, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_MEMORY_ARENA_HPP
#define SHARE_MEMORY_ARENA_HPP
#include "memory/allocation.hpp"
#include "runtime/globals.hpp"
#include "utilities/align.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/powerOfTwo.hpp"
#include <new>
// The byte alignment to be used by Arena::Amalloc.
#define ARENA_AMALLOC_ALIGNMENT BytesPerLong
#define ARENA_ALIGN(x) (align_up((x), ARENA_AMALLOC_ALIGNMENT))
//------------------------------Chunk------------------------------------------
// Linked list of raw memory chunks
class Chunk: CHeapObj<mtChunk> {
private:
Chunk* _next; // Next Chunk in list
const size_t _len; // Size of this Chunk
public:
void* operator new(size_t size, AllocFailType alloc_failmode, size_t length) throw();
void operator delete(void* p);
Chunk(size_t length);
enum {
// default sizes; make them slightly smaller than 2**k to guard against
// buddy-system style malloc implementations
// Note: please keep these constants 64-bit aligned.
#ifdef _LP64
slack = 40, // [RGV] Not sure if this is right, but make it
// a multiple of 8.
#else
slack = 24, // suspected sizeof(Chunk) + internal malloc headers
#endif
tiny_size = 256 - slack, // Size of first chunk (tiny)
init_size = 1*K - slack, // Size of first chunk (normal aka small)
medium_size= 10*K - slack, // Size of medium-sized chunk
size = 32*K - slack, // Default size of an Arena chunk (following the first)
non_pool_size = init_size + 32 // An initial size which is not one of above
};
void chop(); // Chop this chunk
void next_chop(); // Chop next chunk
static size_t aligned_overhead_size(void) { return ARENA_ALIGN(sizeof(Chunk)); }
static size_t aligned_overhead_size(size_t byte_size) { return ARENA_ALIGN(byte_size); }
size_t length() const { return _len; }
Chunk* next() const { return _next; }
void set_next(Chunk* n) { _next = n; }
// Boundaries of data area (possibly unused)
char* bottom() const { return ((char*) this) + aligned_overhead_size(); }
char* top() const { return bottom() + _len; }
bool contains(char* p) const { return bottom() <= p && p <= top(); }
// Start the chunk_pool cleaner task
static void start_chunk_pool_cleaner_task();
};
//------------------------------Arena------------------------------------------
// Fast allocation of memory
class Arena : public CHeapObjBase {
protected:
friend class HandleMark;
friend class NoHandleMark;
friend class VMStructs;
MEMFLAGS _flags; // Memory tracking flags
Chunk *_first; // First chunk
Chunk *_chunk; // current chunk
char *_hwm, *_max; // High water mark and max in current chunk
// Get a new Chunk of at least size x
void* grow(size_t x, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
size_t _size_in_bytes; // Size of arena (used for native memory tracking)
void* internal_amalloc(size_t x, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM) {
assert(is_aligned(x, BytesPerWord), "misaligned size");
if (pointer_delta(_max, _hwm, 1) >= x) {
char *old = _hwm;
_hwm += x;
return old;
} else {
return grow(x, alloc_failmode);
}
}
public:
Arena(MEMFLAGS memflag);
Arena(MEMFLAGS memflag, size_t init_size);
~Arena();
void destruct_contents();
char* hwm() const { return _hwm; }
// Fast allocate in the arena. Common case aligns to the size of jlong which is 64 bits
// on both 32 and 64 bit platforms. Required for atomic jlong operations on 32 bits.
void* Amalloc(size_t x, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM) {
x = ARENA_ALIGN(x); // note for 32 bits this should align _hwm as well.
// Amalloc guarantees 64-bit alignment and we need to ensure that in case the preceding
// allocation was AmallocWords. Only needed on 32-bit - on 64-bit Amalloc and AmallocWords are
// identical.
assert(is_aligned(_max, ARENA_AMALLOC_ALIGNMENT), "chunk end unaligned?");
NOT_LP64(_hwm = ARENA_ALIGN(_hwm));
return internal_amalloc(x, alloc_failmode);
}
// Allocate in the arena, assuming the size has been aligned to size of pointer, which
// is 4 bytes on 32 bits, hence the name.
void* AmallocWords(size_t x, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM) {
assert(is_aligned(x, BytesPerWord), "misaligned size");
return internal_amalloc(x, alloc_failmode);
}
// Fast delete in area. Common case is: NOP (except for storage reclaimed)
bool Afree(void *ptr, size_t size) {
if (ptr == NULL) {
return true; // as with free(3), freeing NULL is a noop.
}
#ifdef ASSERT
if (ZapResourceArea) memset(ptr, badResourceValue, size); // zap freed memory
#endif
if (((char*)ptr) + size == _hwm) {
_hwm = (char*)ptr;
return true;
} else {
// Unable to fast free, so we just drop it.
return false;
}
}
void *Arealloc( void *old_ptr, size_t old_size, size_t new_size,
AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
// Move contents of this arena into an empty arena
Arena *move_contents(Arena *empty_arena);
// Determine if pointer belongs to this Arena or not.
bool contains( const void *ptr ) const;
// Total of all chunks in use (not thread-safe)
size_t used() const;
// Total # of bytes used
size_t size_in_bytes() const { return _size_in_bytes; };
void set_size_in_bytes(size_t size);
private:
// Reset this Arena to empty, access will trigger grow if necessary
void reset(void) {
_first = _chunk = NULL;
_hwm = _max = NULL;
set_size_in_bytes(0);
}
};
// One of the following macros must be used when allocating
// an array or object from an arena
#define NEW_ARENA_ARRAY(arena, type, size) \
(type*) (arena)->Amalloc((size) * sizeof(type))
#define REALLOC_ARENA_ARRAY(arena, type, old, old_size, new_size) \
(type*) (arena)->Arealloc((char*)(old), (old_size) * sizeof(type), \
(new_size) * sizeof(type) )
#define FREE_ARENA_ARRAY(arena, type, old, size) \
(arena)->Afree((char*)(old), (size) * sizeof(type))
#define NEW_ARENA_OBJ(arena, type) \
NEW_ARENA_ARRAY(arena, type, 1)
#endif // SHARE_MEMORY_ARENA_HPP
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