mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-27 00:21:05 +00:00
335 lines
7.3 KiB
C++
335 lines
7.3 KiB
C++
/*
|
|
* Copyright (c)2013-2020 ZeroTier, Inc.
|
|
*
|
|
* Use of this software is governed by the Business Source License included
|
|
* in the LICENSE.TXT file in the project's root directory.
|
|
*
|
|
* Change Date: 2026-01-01
|
|
*
|
|
* On the date above, in accordance with the Business Source License, use
|
|
* of this software will be governed by version 2.0 of the Apache License.
|
|
*/
|
|
/****/
|
|
|
|
#ifndef ZT_RINGBUFFER_H
|
|
#define ZT_RINGBUFFER_H
|
|
|
|
#include <typeinfo>
|
|
#include <cstdint>
|
|
#include <stdlib.h>
|
|
#include <memory.h>
|
|
#include <algorithm>
|
|
#include <math.h>
|
|
|
|
namespace ZeroTier {
|
|
|
|
/**
|
|
* A circular buffer
|
|
*
|
|
* For fast handling of continuously-evolving variables (such as path quality metrics).
|
|
* Using this, we can maintain longer sliding historical windows for important path
|
|
* metrics without the need for potentially expensive calls to memcpy/memmove.
|
|
*
|
|
* Some basic statistical functionality is implemented here in an attempt
|
|
* to reduce the complexity of code needed to interact with this type of buffer.
|
|
*/
|
|
|
|
template <class T,size_t S>
|
|
class RingBuffer
|
|
{
|
|
private:
|
|
T buf[S];
|
|
size_t begin;
|
|
size_t end;
|
|
bool wrap;
|
|
|
|
public:
|
|
RingBuffer() :
|
|
begin(0),
|
|
end(0),
|
|
wrap(false)
|
|
{
|
|
memset(buf,0,sizeof(T)*S);
|
|
}
|
|
|
|
/**
|
|
* @return A pointer to the underlying buffer
|
|
*/
|
|
inline T *get_buf()
|
|
{
|
|
return buf + begin;
|
|
}
|
|
|
|
/**
|
|
* Adjust buffer index pointer as if we copied data in
|
|
* @param n Number of elements to copy in
|
|
* @return Number of elements we copied in
|
|
*/
|
|
inline size_t produce(size_t n)
|
|
{
|
|
n = std::min(n, getFree());
|
|
if (n == 0) {
|
|
return n;
|
|
}
|
|
const size_t first_chunk = std::min(n, S - end);
|
|
end = (end + first_chunk) % S;
|
|
if (first_chunk < n) {
|
|
const size_t second_chunk = n - first_chunk;
|
|
end = (end + second_chunk) % S;
|
|
}
|
|
if (begin == end) {
|
|
wrap = true;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
/**
|
|
* Fast erase, O(1).
|
|
* Merely reset the buffer pointer, doesn't erase contents
|
|
*/
|
|
inline void reset() { consume(count()); }
|
|
|
|
/**
|
|
* adjust buffer index pointer as if we copied data out
|
|
* @param n Number of elements we copied from the buffer
|
|
* @return Number of elements actually available from the buffer
|
|
*/
|
|
inline size_t consume(size_t n)
|
|
{
|
|
n = std::min(n, count());
|
|
if (n == 0) {
|
|
return n;
|
|
}
|
|
if (wrap) {
|
|
wrap = false;
|
|
}
|
|
const size_t first_chunk = std::min(n, S - begin);
|
|
begin = (begin + first_chunk) % S;
|
|
if (first_chunk < n) {
|
|
const size_t second_chunk = n - first_chunk;
|
|
begin = (begin + second_chunk) % S;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
/**
|
|
* @param data Buffer that is to be written to the ring
|
|
* @param n Number of elements to write to the buffer
|
|
*/
|
|
inline size_t write(const T * data, size_t n)
|
|
{
|
|
n = std::min(n, getFree());
|
|
if (n == 0) {
|
|
return n;
|
|
}
|
|
const size_t first_chunk = std::min(n, S - end);
|
|
memcpy(buf + end, data, first_chunk * sizeof(T));
|
|
end = (end + first_chunk) % S;
|
|
if (first_chunk < n) {
|
|
const size_t second_chunk = n - first_chunk;
|
|
memcpy(buf + end, data + first_chunk, second_chunk * sizeof(T));
|
|
end = (end + second_chunk) % S;
|
|
}
|
|
if (begin == end) {
|
|
wrap = true;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
/**
|
|
* Place a single value on the buffer. If the buffer is full, consume a value first.
|
|
*
|
|
* @param value A single value to be placed in the buffer
|
|
*/
|
|
inline void push(const T value)
|
|
{
|
|
if (count() == S) {
|
|
consume(1);
|
|
}
|
|
const size_t first_chunk = std::min((size_t)1, S - end);
|
|
*(buf + end) = value;
|
|
end = (end + first_chunk) % S;
|
|
if (begin == end) {
|
|
wrap = true;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @return The most recently pushed element on the buffer
|
|
*/
|
|
inline T get_most_recent() { return *(buf + end); }
|
|
|
|
/**
|
|
* @param dest Destination buffer
|
|
* @param n Size (in terms of number of elements) of the destination buffer
|
|
* @return Number of elements read from the buffer
|
|
*/
|
|
inline size_t read(T *dest,size_t n)
|
|
{
|
|
n = std::min(n, count());
|
|
if (n == 0) {
|
|
return n;
|
|
}
|
|
if (wrap) {
|
|
wrap = false;
|
|
}
|
|
const size_t first_chunk = std::min(n, S - begin);
|
|
memcpy(dest, buf + begin, first_chunk * sizeof(T));
|
|
begin = (begin + first_chunk) % S;
|
|
if (first_chunk < n) {
|
|
const size_t second_chunk = n - first_chunk;
|
|
memcpy(dest + first_chunk, buf + begin, second_chunk * sizeof(T));
|
|
begin = (begin + second_chunk) % S;
|
|
}
|
|
return n;
|
|
}
|
|
|
|
/**
|
|
* Return how many elements are in the buffer, O(1).
|
|
*
|
|
* @return The number of elements in the buffer
|
|
*/
|
|
inline size_t count()
|
|
{
|
|
if (end == begin) {
|
|
return wrap ? S : 0;
|
|
} else if (end > begin) {
|
|
return end - begin;
|
|
} else {
|
|
return S + end - begin;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @return The number of slots that are unused in the buffer
|
|
*/
|
|
inline size_t getFree() { return S - count(); }
|
|
|
|
/**
|
|
* @return The arithmetic mean of the contents of the buffer
|
|
*/
|
|
inline float mean()
|
|
{
|
|
size_t iterator = begin;
|
|
float subtotal = 0;
|
|
size_t curr_cnt = count();
|
|
for (size_t i=0; i<curr_cnt; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
subtotal += (float)*(buf + iterator);
|
|
}
|
|
return curr_cnt ? subtotal / (float)curr_cnt : 0;
|
|
}
|
|
|
|
/**
|
|
* @return The arithmetic mean of the most recent 'n' elements of the buffer
|
|
*/
|
|
inline float mean(size_t n)
|
|
{
|
|
n = n < S ? n : S;
|
|
size_t iterator = begin;
|
|
float subtotal = 0;
|
|
size_t curr_cnt = count();
|
|
for (size_t i=0; i<n; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
subtotal += (float)*(buf + iterator);
|
|
}
|
|
return curr_cnt ? subtotal / (float)curr_cnt : 0;
|
|
}
|
|
|
|
/**
|
|
* @return The sum of the contents of the buffer
|
|
*/
|
|
inline float sum()
|
|
{
|
|
size_t iterator = begin;
|
|
float total = 0;
|
|
size_t curr_cnt = count();
|
|
for (size_t i=0; i<curr_cnt; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
total += (float)*(buf + iterator);
|
|
}
|
|
return total;
|
|
}
|
|
|
|
/**
|
|
* @return The sample standard deviation of element values
|
|
*/
|
|
inline float stddev() { return sqrt(variance()); }
|
|
|
|
/**
|
|
* @return The variance of element values
|
|
*/
|
|
inline float variance()
|
|
{
|
|
size_t iterator = begin;
|
|
float cached_mean = mean();
|
|
size_t curr_cnt = count();
|
|
T sum_of_squared_deviations = 0;
|
|
for (size_t i=0; i<curr_cnt; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
float deviation = (buf[i] - cached_mean);
|
|
sum_of_squared_deviations += (T)(deviation*deviation);
|
|
}
|
|
float variance = (float)sum_of_squared_deviations / (float)(S - 1);
|
|
return variance;
|
|
}
|
|
|
|
/**
|
|
* @return The number of elements of zero value
|
|
*/
|
|
inline size_t zeroCount()
|
|
{
|
|
size_t iterator = begin;
|
|
size_t zeros = 0;
|
|
size_t curr_cnt = count();
|
|
for (size_t i=0; i<curr_cnt; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
if (*(buf + iterator) == 0) {
|
|
zeros++;
|
|
}
|
|
}
|
|
return zeros;
|
|
}
|
|
|
|
/**
|
|
* @param value Value to match against in buffer
|
|
* @return The number of values held in the ring buffer which match a given value
|
|
*/
|
|
inline size_t countValue(T value)
|
|
{
|
|
size_t iterator = begin;
|
|
size_t cnt = 0;
|
|
size_t curr_cnt = count();
|
|
for (size_t i=0; i<curr_cnt; i++) {
|
|
iterator = (iterator + S - 1) % curr_cnt;
|
|
if (*(buf + iterator) == value) {
|
|
cnt++;
|
|
}
|
|
}
|
|
return cnt;
|
|
}
|
|
|
|
/**
|
|
* Print the contents of the buffer
|
|
*/
|
|
/*
|
|
inline void dump()
|
|
{
|
|
size_t iterator = begin;
|
|
for (size_t i=0; i<S; i++) {
|
|
iterator = (iterator + S - 1) % S;
|
|
if (typeid(T) == typeid(int)) {
|
|
fprintf(stderr, "buf[%2zu]=%2d\n", iterator, (int)*(buf + iterator));
|
|
}
|
|
else {
|
|
fprintf(stderr, "buf[%2zu]=%2f\n", iterator, (float)*(buf + iterator));
|
|
}
|
|
}
|
|
}
|
|
*/
|
|
};
|
|
|
|
} // namespace ZeroTier
|
|
|
|
#endif
|