Commit 3396a038 authored by Alexandre Duret-Lutz's avatar Alexandre Duret-Lutz
Browse files

Add a fixed-size memory pool implementation.

* src/misc/fixpool.hh: New file.
* src/misc/Makefile.am (misc_HEADERS): Add fixpool.hh.
parent 050ea69f
2011-04-03 Alexandre Duret-Lutz <adl@lrde.epita.fr>
Add a fixed-size memory pool implementation.
* src/misc/fixpool.hh: New file.
* src/misc/Makefile.am (misc_HEADERS): Add fixpool.hh.
2011-04-03 Alexandre Duret-Lutz <adl@lrde.epita.fr>
* HACKING (command): Some notes about link-time optimizations.
......
......@@ -33,6 +33,7 @@ misc_HEADERS = \
bddop.hh \
casts.hh \
escape.hh \
fixpool.hh \
freelist.hh \
hash.hh \
hashfunc.hh \
......
// Copyright (C) 2011 Laboratoire de Recherche et Developpement de
// l'Epita (LRDE)
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// Spot 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with Spot; see the file COPYING. If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
#ifndef SPOT_MISC_FIXPOOL_HH
# define SPOT_MISC_FIXPOOL_HH
#include <new>
#include <cstddef>
#include <cstdlib>
#include <cassert>
namespace spot
{
/// A fixed-size memory pool implementation.
class fixed_size_pool
{
public:
/// Create a pool allocating objects of \a size bytes.
fixed_size_pool(size_t size)
: freelist_(0), free_start_(0), free_end_(0), chunklist_(0)
{
const size_t alignement = 2 * sizeof(size_t);
size_ = ((size >= sizeof(block_) ? size : sizeof(block_))
+ alignement - 1) & ~(alignement - 1);
}
/// Free any memory allocated by this pool.
~fixed_size_pool()
{
while (chunklist_)
{
chunk_* prev = chunklist_->prev;
free(chunklist_);
chunklist_ = prev;
}
}
/// Allocate \a size bytes of memory.
void*
allocate()
{
block_* f = freelist_;
// If we have free blocks available, return the first one.
if (f)
{
freelist_ = f->next;
return f;
}
// Else, create a block out of the last chunk of allocated
// memory.
// If all the last chunk has been used, allocate one more.
if (free_start_ + size_ > free_end_)
{
const size_t requested = (size_ > 128 ? size_ : 128) * 8192 - 64;
chunk_* c = reinterpret_cast<chunk_*>(malloc(requested));
if (!c)
throw std::bad_alloc();
c->prev = chunklist_;
chunklist_ = c;
free_start_ = c->data_ + size_;
free_end_ = c->data_ + requested;
}
void* res = free_start_;
free_start_ += size_;
return res;
}
/// \brief Recycle \a size bytes of memory.
///
/// Despite the name, the memory is not really deallocate in the
/// "delete" sense: it is still owned by the pool and will be
/// reused by allocate as soon as possible. The memory is only
/// freed when the pool is destroyed.
void
deallocate (const void* ptr)
{
assert(ptr);
block_* b = reinterpret_cast<block_*>(const_cast<void*>(ptr));
b->next = freelist_;
freelist_ = b;
}
private:
size_t size_;
struct block_ { block_* next; }* freelist_;
char* free_start_;
char* free_end_;
// chunk = several agglomerated blocks
union chunk_ { chunk_* prev; char data_[1]; }* chunklist_;
};
}
#endif // SPOT_MISC_FIXPOOL_HH
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