block_alloc.h

/***************************************************************************
 * include/stxxl/bits/mng/block_alloc.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2002-2007 Roman Dementiev <[email protected]>
 * Copyright (C) 2007-2009 Andreas Beckmann <[email protected]>
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#ifndef STXXL_MNG__BLOCK_ALLOC_H
#define STXXL_MNG__BLOCK_ALLOC_H

#include <algorithm>
#include <stxxl/bits/parallel.h>
#include <stxxl/bits/common/rand.h>
#include <stxxl/bits/mng/config.h>


__STXXL_BEGIN_NAMESPACE



struct basic_allocation_strategy
{
 basic_allocation_strategy(int disks_begin, int disks_end);
 basic_allocation_strategy();
 int operator () (int i) const;
 static const char * name();
};

struct striping
{
 int begin, diff;

public:
 striping(int b, int e) : begin(b), diff(e - b)
 { }

 striping() : begin(0)
 {
 diff = config::get_instance()->disks_number();
 }

 int operator () (int i) const
 {
 return begin + i % diff;
 }

 static const char * name()
 {
 return "striping";
 }
};

struct FR : public striping
{
private:
 random_number<random_uniform_fast> rnd;

public:
 FR(int b, int e) : striping(b, e)
 { }

 FR() : striping()
 { }

 int operator () (int /*i*/) const
 {
 return begin + rnd(diff);
 }

 static const char * name()
 {
 return "fully randomized striping";
 }
};

struct SR : public striping
{
private:
 int offset;

 void init()
 {
 random_number<random_uniform_fast> rnd;
 offset = rnd(diff);
 }

public:
 SR(int b, int e) : striping(b, e)
 {
 init();
 }

 SR() : striping()
 {
 init();
 }

 int operator () (int i) const
 {
 return begin + (i + offset) % diff;
 }

 static const char * name()
 {
 return "simple randomized striping";
 }
};

struct RC : public striping
{
private:
 std::vector<int> perm;

 void init()
 {
 for (int i = 0; i < diff; i++)
 perm[i] = i;

 stxxl::random_number<random_uniform_fast> rnd;
 std::random_shuffle(perm.begin(), perm.end(), rnd _STXXL_FORCE_SEQUENTIAL);
 }

public:
 RC(int b, int e) : striping(b, e), perm(diff)
 {
 init();
 }

 RC() : striping(), perm(diff)
 {
 init();
 }

 int operator () (int i) const
 {
 return begin + perm[i % diff];
 }

 static const char * name()
 {
 return "randomized cycling striping";
 }
};

struct RC_disk : public RC
{
 RC_disk(int b, int e) : RC(b, e)
 { }

 RC_disk() : RC(config::get_instance()->regular_disk_range().first, config::get_instance()->regular_disk_range().second)
 { }

 static const char * name()
 {
 return "Randomized cycling striping on regular disks";
 }
};

struct RC_flash : public RC
{
 RC_flash(int b, int e) : RC(b, e)
 { }

 RC_flash() : RC(config::get_instance()->flash_range().first, config::get_instance()->flash_range().second)
 { }

 static const char * name()
 {
 return "Randomized cycling striping on flash devices";
 }
};

struct single_disk
{
 const int disk;
 single_disk(int d, int = 0) : disk(d)
 { }

 single_disk() : disk(0)
 { }

 int operator () (int /*i*/) const
 {
 return disk;
 }

 static const char * name()
 {
 return "single disk";
 }
};


template <class BaseAllocator_>
struct offset_allocator
{
 BaseAllocator_ base;
 int_type offset;

 offset_allocator(int_type offset_, const BaseAllocator_ & base_) : base(base_), offset(offset_)
 { }

 offset_allocator(const BaseAllocator_ & base_) : base(base_), offset(0)
 { }

 offset_allocator() : offset(0)
 { }

 int operator () (int_type i) const
 {
 return base(offset + i);
 }

 int_type get_offset() const
 {
 return offset;
 }

 void set_offset(int_type i)
 {
 offset = i;
 }
};

#ifndef STXXL_DEFAULT_ALLOC_STRATEGY
 #define STXXL_DEFAULT_ALLOC_STRATEGY stxxl::RC
#endif


__STXXL_END_NAMESPACE

#endif // !STXXL_MNG__BLOCK_ALLOC_H
// vim: et:ts=4:sw=4