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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2018-2024 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#include "xfs.h"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <pthread.h>
#include "libfrog/ptvar.h"
#include "counter.h"
/*
* Per-Thread Counters
*
* This is a global counter object that uses per-thread counters to
* count things without having to content for a single shared lock.
* Provided we know the number of threads that will be accessing the
* counter, each thread gets its own thread-specific counter variable.
* Changing the value is fast, though retrieving the value is expensive
* and approximate.
*/
struct ptcounter {
struct ptvar *var;
};
/* Allocate per-thread counter. */
int
ptcounter_alloc(
size_t nr,
struct ptcounter **pp)
{
struct ptcounter *p;
int ret;
p = malloc(sizeof(struct ptcounter));
if (!p)
return errno;
ret = -ptvar_alloc(nr, sizeof(uint64_t), &p->var);
if (ret) {
free(p);
return ret;
}
*pp = p;
return 0;
}
/* Free per-thread counter. */
void
ptcounter_free(
struct ptcounter *ptc)
{
ptvar_free(ptc->var);
free(ptc);
}
/* Add a quantity to the counter. */
int
ptcounter_add(
struct ptcounter *ptc,
int64_t nr)
{
uint64_t *p;
int ret;
p = ptvar_get(ptc->var, &ret);
if (ret)
return -ret;
*p += nr;
return 0;
}
static int
ptcounter_val_helper(
struct ptvar *ptv,
void *data,
void *foreach_arg)
{
uint64_t *sum = foreach_arg;
uint64_t *count = data;
*sum += *count;
return 0;
}
/* Return the approximate value of this counter. */
int
ptcounter_value(
struct ptcounter *ptc,
uint64_t *sum)
{
*sum = 0;
return -ptvar_foreach(ptc->var, ptcounter_val_helper, sum);
}