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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2009
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <cmath>
namespace Gecode { namespace Kernel {
/// Global propagator information
class GPI {
public:
/// Class for storing propagator information
class Info {
public:
/// Propagator identifier
unsigned int pid;
/// Group identifier
unsigned int gid;
/// The afc value
double afc;
/// Initialize
void init(unsigned int pid, unsigned int gid);
};
private:
/// Block of propagator information
class Block : public HeapAllocated {
public:
/// Number of propagator information entries in a block
static const int n_info = 8192;
/// Info entries
Info info[n_info];
/// Next block
Block* next;
/// Number of free blocks
int free;
/// Initialize
Block(void);
/// Rescale used afc values in entries
void rescale(void);
};
/// The current block
Block* b;
/// The inverse decay factor
double invd;
/// Next free propagator id
std::atomic<unsigned int> npid;
/// Whether to unshare
bool us;
/// The first block
Block fst;
/// Mutex to synchronize globally shared access
GECODE_KERNEL_EXPORT static Support::Mutex m;
public:
/// Initialize
GPI(void);
/// Set decay factor to \a d
void decay(double d);
/// Return decay factor
double decay(void) const;
/// Increment failure count
void fail(Info& c);
/// Allocate info for existing propagator with pid \a p
Info* allocate(unsigned int p, unsigned int gid);
/// Allocate new actor info
Info* allocate(unsigned int gid);
/// Return next free propagator id
unsigned int pid(void) const;
/// Provide access to unshare info and set to true
bool unshare(void);
/// Delete
~GPI(void);
};
forceinline void
GPI::Info::init(unsigned int pid0, unsigned int gid0) {
pid=pid0; gid=gid0; afc=1.0;
}
forceinline
GPI::Block::Block(void)
: next(nullptr), free(n_info) {}
forceinline void
GPI::Block::rescale(void) {
for (int i=free; i < n_info; i++)
info[i].afc *= Kernel::Config::rescale;
}
forceinline
GPI::GPI(void)
: b(&fst), invd(1.0), npid(0U), us(false) {}
forceinline void
GPI::fail(Info& c) {
m.acquire();
c.afc = invd * (c.afc + 1.0);
if (c.afc > Kernel::Config::rescale_limit)
for (Block* i = b; i != nullptr; i = i->next)
i->rescale();
m.release();
}
forceinline double
GPI::decay(void) const {
double d;
const_cast<GPI&>(*this).m.acquire();
d = 1.0 / invd;
const_cast<GPI&>(*this).m.release();
return d;
}
forceinline unsigned int
GPI::pid(void) const {
return npid.load(std::memory_order_acquire);
}
forceinline bool
GPI::unshare(void) {
bool u;
m.acquire();
u = us; us = true;
m.release();
return u;
}
forceinline void
GPI::decay(double d) {
m.acquire();
invd = 1.0 / d;
m.release();
}
forceinline GPI::Info*
GPI::allocate(unsigned int p, unsigned int gid) {
Info* c;
m.acquire();
if (b->free == 0) {
Block* n = new Block;
n->next = b; b = n;
}
c = &b->info[--b->free];
m.release();
c->init(p,gid);
return c;
}
forceinline GPI::Info*
GPI::allocate(unsigned int gid) {
Info* c;
m.acquire();
if (b->free == 0) {
Block* n = new Block;
n->next = b; b = n;
}
c = &b->info[--b->free];
m.release();
c->init(npid.fetch_add(1, std::memory_order_seq_cst),gid);
return c;
}
forceinline
GPI::~GPI(void) {
Block* n = b;
while (n != &fst) {
Block* d = n;
n = n->next;
delete d;
}
}
}}
// STATISTICS: kernel-prop
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