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/*
* This file is part of the rsyslog runtime library.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
* -or-
* see COPYING.ASL20 in the source distribution
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <math.h>
#include <assert.h>
#include "perctile_ringbuf.h"
static uint64_t min(uint64_t a, uint64_t b) {
return a < b ? a : b;
}
/*
* circ buf macros derived from linux/circ_buf.h
*/
/* Return count in buffer. */
#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))
/* Return space available, 0..size-1. We always leave one free char
as a completely full buffer has head == tail, which is the same as
empty. */
#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))
/* Return count up to the end of the buffer. Carefully avoid
accessing head and tail more than once, so they can change
underneath us without returning inconsistent results. */
#define CIRC_CNT_TO_END(head,tail,size) \
({int end = (size) - (tail); \
int n = ((head) + end) & ((size)-1); \
n < end ? n : end;})
/* Return space available up to the end of the buffer. */
#define CIRC_SPACE_TO_END(head,tail,size) \
({int end = (size) - 1 - (head); \
int n = (end + (tail)) & ((size)-1); \
n <= end ? n : end+1;})
/* Move head by size. */
#define CIRC_ADD(idx, size, offset) (((idx) + (offset)) & ((size) - 1))
// simple use of the linux defined circular buffer.
ringbuf_t* ringbuf_new(size_t count) {
// use nearest power of 2
double x = ceil(log2(count));
size_t bufsize = pow(2, x);
ringbuf_t *rb = calloc(1, sizeof(ringbuf_t));
// Note: count needs to be a power of 2, otherwise our macros won't work.
ITEM *pbuf = calloc(bufsize, sizeof(ITEM));
rb->cb.buf = pbuf;
rb->cb.head = rb->cb.tail = 0;
rb->size = bufsize;
return rb;
}
void ringbuf_del(ringbuf_t *rb) {
if (rb) {
if (rb->cb.buf) {
free(rb->cb.buf);
}
free(rb);
}
}
int ringbuf_append(ringbuf_t *rb, ITEM item) {
// lock it and add
int head = rb->cb.head,
tail = rb->cb.tail;
if (!CIRC_SPACE(head, tail, rb->size)) {
return -1;
} else {
/* insert item into buffer */
rb->cb.buf[head] = item;
// move head
rb->cb.head = CIRC_ADD(head, rb->size, 1);
}
return 0;
}
int ringbuf_append_with_overwrite(ringbuf_t *rb, ITEM item) {
int head = rb->cb.head,
tail = rb->cb.tail;
int ret = 0;
if (!CIRC_SPACE(head, tail, rb->size)) {
rb->cb.tail = CIRC_ADD(tail, rb->size, 1);
}
ret = ringbuf_append(rb, item);
assert(ret == 0); // we shouldn't fail due to no space.
return ret;
}
int ringbuf_read(ringbuf_t *rb, ITEM *buf, size_t count) {
int head = rb->cb.head,
tail = rb->cb.tail;
size_t copy_size = 0;
if (!CIRC_CNT(head, tail, rb->size)) {
return 0;
}
// copy to end of buffer
copy_size = min((size_t)CIRC_CNT_TO_END(head, tail, rb->size), count);
memcpy(buf, rb->cb.buf+tail, copy_size*sizeof(ITEM));
rb->cb.tail = CIRC_ADD(rb->cb.tail, rb->size, copy_size);
return copy_size;
}
size_t ringbuf_read_to_end(ringbuf_t *rb, ITEM *buf, size_t count) {
size_t nread = 0;
nread += ringbuf_read(rb, buf, count);
if (nread == 0) {
return nread;
}
// read the rest if buf circled around
nread += ringbuf_read(rb, buf + nread, count - nread);
assert(nread <= count);
return nread;
}
bool ringbuf_peek(ringbuf_t *rb, ITEM *item) {
if (CIRC_CNT(rb->cb.head, rb->cb.tail, rb->size) == 0) {
return false;
}
*item = rb->cb.buf[rb->cb.tail];
return true;
}
size_t ringbuf_capacity(ringbuf_t *rb) {
return rb->size;
}
/* ---- RINGBUFFER TESTS ---- */
void ringbuf_init_test(void) {
size_t count = 4;
ringbuf_t *rb = ringbuf_new(count);
// verify ringbuf empty state
assert(rb->cb.head == 0);
assert(rb->cb.tail == 0);
assert(rb->size == 4);
ringbuf_del(rb);
}
void ringbuf_simple_test(void) {
size_t count = 3;
ITEM item = 0;
ringbuf_t *rb = ringbuf_new(count);
assert(ringbuf_append(rb, 1) == 0);
assert(ringbuf_append(rb, 2) == 0);
assert(ringbuf_append(rb, 3) == 0);
item = 0;
assert(ringbuf_peek(rb, &item) == 0);
assert(item == 1);
}
void ringbuf_append_test(void) {
size_t count = 4;
ringbuf_t *rb = ringbuf_new(count);
assert(ringbuf_append(rb, 1) == 0);
assert(ringbuf_append(rb, 2) == 0);
assert(ringbuf_append(rb, 3) == 0);
// check state of ringbuffer:
// {1, 2, 3, X}
// T H
assert(rb->cb.buf[0] == 1);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.buf[3] == 0);
assert(rb->cb.head == 3);
assert(rb->cb.tail == 0);
ringbuf_del(rb);
}
void ringbuf_append_wrap_test(void) {
size_t count = 4;
ITEM item = 0;
ringbuf_t *rb = ringbuf_new(count);
assert(ringbuf_append(rb, 1) == 0);
assert(ringbuf_append(rb, 2) == 0);
assert(ringbuf_append(rb, 3) == 0);
assert(ringbuf_append(rb, 4) != 0);
// check state of ringbuffer:
// {1, 2, 3, X}
// T H
assert(rb->cb.buf[0] == 1);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.head == 3);
assert(rb->cb.tail == 0);
item = 0;
assert(ringbuf_read(rb, &item, 1) == 1);
assert(item == 1);
assert(ringbuf_append(rb, 4) == 0);
// state of ringbuffer:
// {1, 2, 3, 4}
// H T
assert(rb->cb.buf[0] == 1);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.buf[3] == 4);
assert(rb->cb.head == 0);
assert(rb->cb.tail == 1);
item = 0;
assert(ringbuf_read(rb, &item, 1) == 1);
assert(item == 2);
// test wraparound
assert(ringbuf_append(rb, 5) == 0);
// state of ringbuffer:
// {1, 2, 3, 4}
// H T
assert(rb->cb.buf[0] == 5);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.buf[3] == 4);
assert(rb->cb.head == 1);
assert(rb->cb.tail == 2);
ringbuf_del(rb);
}
void ringbuf_append_overwrite_test(void) {
size_t count = 4;
ringbuf_t *rb = ringbuf_new(count);
assert(ringbuf_append_with_overwrite(rb, 1) == 0);
assert(ringbuf_append_with_overwrite(rb, 2) == 0);
assert(ringbuf_append_with_overwrite(rb, 3) == 0);
assert(ringbuf_append_with_overwrite(rb, 4) == 0);
// check state of ringbuffer:
// {1, 2, 3, 4}
// H T
assert(rb->cb.buf[0] == 1);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.buf[3] == 4);
assert(rb->cb.head == 0);
assert(rb->cb.tail == 1);
assert(ringbuf_append_with_overwrite(rb, 5) == 0);
// check state of ringbuffer:
// {5, 2, 3, 4}
// H T
assert(rb->cb.buf[0] == 5);
assert(rb->cb.buf[1] == 2);
assert(rb->cb.buf[2] == 3);
assert(rb->cb.buf[3] == 4);
assert(rb->cb.head == 1);
assert(rb->cb.tail == 2);
ringbuf_del(rb);
}
void ringbuf_read_test(void) {
size_t count = 4;
ringbuf_t *rb = ringbuf_new(count);
ITEM item_array[3];
ITEM expects[] = {1, 2, 3};
ITEM expects2[] = {4};
assert(ringbuf_append_with_overwrite(rb, 1) == 0);
assert(ringbuf_append_with_overwrite(rb, 2) == 0);
assert(ringbuf_append_with_overwrite(rb, 3) == 0);
assert(ringbuf_read(rb, item_array, count) == 3);
assert(memcmp(item_array, expects, 3) == 0);
// check state of ringbuffer:
// {X, X, X, X}
// H
// T
assert(rb->cb.head == 3);
assert(rb->cb.tail == 3);
assert(ringbuf_append_with_overwrite(rb, 4) == 0);
assert(ringbuf_read(rb, item_array, count) == 1);
assert(memcmp(item_array, expects2, 1) == 0);
assert(rb->cb.head == 0);
assert(rb->cb.tail == 0);
ringbuf_del(rb);
}
void ringbuf_read_to_end_test(void) {
size_t count = 4;
ringbuf_t *rb = ringbuf_new(count);
ITEM item_array[3];
ITEM expects[] = {1, 2, 3};
ITEM expects2[] = {4};
assert(ringbuf_append_with_overwrite(rb, 1) == 0);
assert(ringbuf_append_with_overwrite(rb, 2) == 0);
assert(ringbuf_append_with_overwrite(rb, 3) == 0);
// state of ringbuffer:
// {1, 2, 3, X}
// T H
assert(ringbuf_read_to_end(rb, item_array, 3) == 3);
assert(memcmp(item_array, expects, 3) == 0);
// check state of ringbuffer:
// {1, 2, 3, X}
// H
// T
assert(rb->cb.head == 3);
assert(rb->cb.tail == 3);
assert(ringbuf_append_with_overwrite(rb, 4) == 0);
// state of ringbuffer:
// {1, 2, 3, 4}
// H T
assert(ringbuf_read_to_end(rb, item_array, count) == 1);
// check state of ringbuffer (empty):
// {1, 2, 3, 4}
// H
// T
assert(memcmp(item_array, expects2, 1) == 0);
assert(rb->cb.head == 0);
assert(rb->cb.tail == 0);
ringbuf_del(rb);
}
/* ---- END RINGBUFFER TESTS ---- */
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