/usr/include/madness/world/dqueue.h is in libmadness-dev 0.10-3.
This file is owned by root:root, with mode 0o644.
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This file is part of MADNESS.
Copyright (C) 2007,2010 Oak Ridge National Laboratory
This program 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.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
For more information please contact:
Robert J. Harrison
Oak Ridge National Laboratory
One Bethel Valley Road
P.O. Box 2008, MS-6367
email: harrisonrj@ornl.gov
tel: 865-241-3937
fax: 865-572-0680
$Id$
*/
#ifndef MADNESS_WORLD_DQUEUE_H__INCLUDED
#define MADNESS_WORLD_DQUEUE_H__INCLUDED
#include <madness/world/worldmutex.h>
#include <cstddef>
#include <utility>
#include <algorithm>
#include <iostream>
#include <stdint.h>
/// \file dqueue.h
/// \brief Implements DQueue
namespace madness {
struct DQStats { // Dilly bar, blizzard, ...
uint64_t npush_back; ///< #calls to push_back
uint64_t npush_front; ///< #calls to push_front
uint64_t npop_front; ///< #calls to pop_front
uint64_t ngrow; ///< #calls to grow
uint64_t nmax; ///< Lifetime max. entries in the queue
DQStats()
: npush_back(0), npush_front(0), npop_front(0), ngrow(0), nmax(0) {}
};
/// A thread safe, fast but simple doubled-ended queue.
/// Since the point is speed, the implementation is a circular
/// buffer rather than a linked list so as to avoid the new/del
/// overhead. It will grow as needed, but presently will not
/// shrink. Had to modify STL API to make things thread safe.
///
/// It is now rather heavily specialized to its only use.
template <typename T>
class DQueue : private CONDITION_VARIABLE_TYPE {
char pad[64]; ///< To put the lock and the data in separate cache lines
volatile size_t n __attribute__((aligned(64))); ///< Number of elements in the buffer
volatile size_t sz; ///< Current capacity
volatile T* volatile buf; ///< Actual buffer
volatile int _front; ///< Index of element at front of buffer
volatile int _back; ///< Index of element at back of buffer
DQStats stats;
void grow() {
// ASSUME WE ALREADY HAVE THE MUTEX WHEN IN HERE
++(stats.ngrow);
if (sz != n) MADNESS_EXCEPTION("assertion failure in dqueue::grow", static_cast<int>(sz));
size_t oldsz = sz;
if (sz < 32768)
sz = 65536;
else if (sz <= 1048576)
sz *= 2;
else
sz += 1048576;
volatile T* volatile nbuf = new T[sz];
int lo = sz/2 - oldsz/2;
for (int i=_front; i<int(oldsz); ++i,++lo) {
nbuf[lo] = buf[i];
}
if (_front > 0) {
for (int i=0; i<=_back; ++i,++lo) {
nbuf[lo] = buf[i];
}
}
_front = sz/2 - oldsz/2;
_back = _front + n - 1;
delete [] buf;
buf = nbuf;
//sanity_check();
}
void sanity_check() const {
// ASSUME WE ALREADY HAVE THE MUTEX WHEN IN HERE
int num = _back - _front + 1;
if (num < 0) num += sz;
if (num==int(sz) && n==0) num=0;
if (num==0 && n==sz) num=sz;
//if (long(n) != num) print("size",sz,"front",_front,"back",_back,"n",n,"num",num);
MADNESS_ASSERT(long(n) == num);
}
void push_back_with_lock(const T& value) {
size_t nn = n;
size_t ss = sz;
if (nn == ss) {
grow();
ss = sz;
}
++nn;
if (nn > stats.nmax) stats.nmax = nn;
n = nn;
int b = _back + 1;
if (b >= int(ss)) b = 0;
buf[b] = value;
_back = b;
++(stats.npush_back);
signal();
}
public:
DQueue(size_t hint=200000) // was 32768
: n(0)
, sz(hint>2 ? hint : 2)
, buf(new T[sz])
, _front(sz/2)
, _back(_front-1) {}
virtual ~DQueue() {
delete [] buf;
}
/// Insert value at front of queue
void push_front(const T& value) {
madness::ScopedMutex<CONDITION_VARIABLE_TYPE> obolus(this);
//sanity_check();
size_t nn = n;
size_t ss = sz;
if (nn == ss) {
grow();
ss = sz;
}
++nn;
if (nn > stats.nmax) stats.nmax = nn;
n = nn;
int f = _front - 1;
if (f < 0) f = ss - 1;
buf[f] = value;
_front = f;
++(stats.npush_front);
//sanity_check();
signal();
//broadcast();
}
/// Insert element at back of queue (default is just one copy)
void push_back(const T& value, int ncopy=1) {
madness::ScopedMutex<CONDITION_VARIABLE_TYPE> obolus(this);
//sanity_check();
while (ncopy--)
push_back_with_lock(value);
//sanity_check();
//broadcast();
}
template <typename opT>
void scan(opT& op) {
madness::ScopedMutex<CONDITION_VARIABLE_TYPE> obolus(this);
int f = _front;
size_t nn = n;
int size = int(sz);
std::cout << "IN Q " << nn << std::endl;
while (nn--) {
T* p = const_cast<T*>(buf + f);
if (!op(p)) break;
++f;
if (f >= size) f = 0;
}
}
/// Pop multiple values off the front of queue ... returns number popped ... might be zero
/// r must refer to an array of dimension at least nmax ... you are presently
/// given no more than max(size()/64,1) values ... arbitrary choice.
///
/// multi-threaded tasks might cause fewer tasks to be taken
int pop_front(int nmax, T* r, bool wait) {
madness::ScopedMutex<CONDITION_VARIABLE_TYPE> obolus(this);
size_t nn = n;
if (nn==0 && wait) {
while (n == 0) // !!! Must be n (memory) not nn (local copy)
CONDITION_VARIABLE_TYPE::wait();
nn = n;
}
++(stats.npop_front);
if (nn) {
size_t thesize = sz;
//sanity_check();
nmax = std::min(nmax,std::max(int(nn>>6),1));
int retval; // Will return the number of items taken
int f = _front;
// Original loop was this
//retval = nmax;
//while (nmax--) {
// *r++ = buf[f++];
// if (f >= int(sz)) f = 0;
//}
// New loop includes checking for replicated multi-threaded task
// ... take one task and then check that subsequent tasks differ
nmax--;
*r++ = buf[f++];
if (f >= int(thesize)) f = 0;
retval=1;
while (nmax--) {
T ptr = buf[f];
if (ptr == *(r-1)) {
break;
}
else if (ptr) { // Null pointer indicates stolen task
*r++ = ptr;
++f;
if (f >= int(thesize)) f = 0;
++retval;
}
}
n = nn - retval;
_front = f;
//sanity_check();
return retval;
}
else {
return 0;
}
}
/// Pop value off the front of queue
std::pair<T,bool> pop_front(bool wait) {
T r;
int ngot = pop_front(1, &r, wait);
return std::pair<T,bool>(r,ngot==1);
}
size_t size() const {
return n;
}
bool empty() const {
return n==0;
}
const DQStats& get_stats() const {
return stats;
}
};
}
#endif // MADNESS_WORLD_DQUEUE_H__INCLUDED
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