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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008 Sun Microsystems
*
* 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; version 2 of the License.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef DRIZZLED_DISCRETE_INTERVAL_H
#define DRIZZLED_DISCRETE_INTERVAL_H
#include <cstdlib>
#include "drizzled/definitions.h"
namespace drizzled
{
/*
Such interval is "discrete": it is the set of
{ auto_inc_interval_min + k * increment,
0 <= k <= (auto_inc_interval_values-1) }
Where "increment" is maintained separately by the user of this class (and is
currently only session->variables.auto_increment_increment).
It mustn't derive from memory::SqlAlloc, because SET INSERT_ID needs to
allocate memory which must stay allocated for use by the next statement.
*/
class Discrete_interval {
private:
uint64_t interval_min;
uint64_t interval_values;
uint64_t interval_max; // excluded bound. Redundant.
public:
Discrete_interval *next; // used when linked into Discrete_intervals_list
void replace(uint64_t start, uint64_t val, uint64_t incr)
{
interval_min= start;
interval_values= val;
interval_max= (val == UINT64_MAX) ? val : start + val * incr;
}
Discrete_interval(uint64_t start, uint64_t val, uint64_t incr) :
interval_min(start), interval_values(val),
interval_max((val == UINT64_MAX) ? val : start + val * incr),
next(NULL)
{}
Discrete_interval() :
interval_min(0), interval_values(0),
interval_max(0), next(NULL)
{}
uint64_t minimum() const { return interval_min; }
uint64_t values() const { return interval_values; }
uint64_t maximum() const { return interval_max; }
/*
If appending [3,5] to [1,2], we merge both in [1,5] (they should have the
same increment for that, user of the class has to ensure that). That is
just a space optimization. Returns 0 if merge succeeded.
*/
bool merge_if_contiguous(uint64_t start, uint64_t val, uint64_t incr)
{
if (interval_max == start)
{
if (val == UINT64_MAX)
{
interval_values= interval_max= val;
}
else
{
interval_values+= val;
interval_max= start + val * incr;
}
return 0;
}
return 1;
}
};
/* List of Discrete_interval objects */
class Discrete_intervals_list {
private:
Discrete_interval *head;
Discrete_interval *tail;
/*
When many intervals are provided at the beginning of the execution of a
statement (in a replication slave or SET INSERT_ID), "current" points to
the interval being consumed by the thread now (so "current" goes from
"head" to "tail" then to NULL).
*/
Discrete_interval *current;
uint32_t elements; // number of elements
/* helper function for copy construct and assignment operator */
void copy_(const Discrete_intervals_list& from)
{
for (Discrete_interval *i= from.head; i; i= i->next)
{
Discrete_interval j= *i;
append(&j);
}
}
public:
Discrete_intervals_list() :
head(NULL), tail(NULL),
current(NULL), elements(0) {}
Discrete_intervals_list(const Discrete_intervals_list& from) :
head(NULL), tail(NULL),
current(NULL), elements(0)
{
copy_(from);
}
Discrete_intervals_list& operator=(const Discrete_intervals_list& from)
{
empty();
copy_(from);
return *this;
}
void empty_no_free()
{
head= current= NULL;
elements= 0;
}
void empty()
{
for (Discrete_interval *i= head; i;)
{
Discrete_interval *next= i->next;
delete i;
i= next;
}
empty_no_free();
}
const Discrete_interval* get_next()
{
Discrete_interval *tmp= current;
if (current != NULL)
current= current->next;
return tmp;
}
~Discrete_intervals_list() { empty(); }
uint64_t minimum() const { return (head ? head->minimum() : 0); }
uint64_t maximum() const { return (head ? tail->maximum() : 0); }
uint32_t nb_elements() const { return elements; }
bool append(uint64_t start, uint64_t val, uint64_t incr)
{
/* first, see if this can be merged with previous */
if ((head == NULL) || tail->merge_if_contiguous(start, val, incr))
{
/* it cannot, so need to add a new interval */
Discrete_interval *new_interval= new Discrete_interval(start, val, incr);
return(append(new_interval));
}
return(0);
}
bool append(Discrete_interval *new_interval)
{
if (unlikely(new_interval == NULL))
return(1);
if (head == NULL)
head= current= new_interval;
else
tail->next= new_interval;
tail= new_interval;
elements++;
return(0);
}
};
} /* namespace drizzled */
#endif /* DRIZZLED_DISCRETE_INTERVAL_H */
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