rqbit/crates/dht/src/routing_table.rs
2021-07-12 16:24:26 +01:00

526 lines
15 KiB
Rust

use std::{
net::SocketAddr,
time::{Duration, Instant},
};
#[derive(Debug)]
enum BucketTreeNode {
Leaf(Vec<RoutingTableNode>),
LeftRight(Box<BucketTree>, Box<BucketTree>),
}
#[derive(Debug)]
pub struct BucketTree {
bits: u8,
start: Id20,
end_inclusive: Id20,
data: BucketTreeNode,
}
pub struct BucketTreeNodeIterator<'a> {
current: std::slice::Iter<'a, RoutingTableNode>,
queue: Vec<&'a BucketTree>,
}
impl<'a> BucketTreeNodeIterator<'a> {
fn new(mut tree: &'a BucketTree) -> Self {
let mut queue = Vec::new();
let current = loop {
match &tree.data {
BucketTreeNode::Leaf(nodes) => break nodes.iter(),
BucketTreeNode::LeftRight(left, right) => {
queue.push(right.as_ref());
tree = left.as_ref()
}
}
};
BucketTreeNodeIterator { current, queue }
}
}
impl<'a> Iterator for BucketTreeNodeIterator<'a> {
type Item = &'a RoutingTableNode;
fn next(&mut self) -> Option<Self::Item> {
if let Some(v) = self.current.next() {
return Some(v);
};
loop {
let tree = self.queue.pop()?;
match &tree.data {
BucketTreeNode::Leaf(nodes) => {
self.current = nodes.iter();
match self.current.next() {
Some(v) => return Some(v),
None => continue,
}
}
BucketTreeNode::LeftRight(left, right) => {
self.queue.push(right.as_ref());
self.queue.push(left.as_ref());
continue;
}
}
}
}
}
pub struct BucketTreeNodeIteratorMut<'a> {
current: std::slice::IterMut<'a, RoutingTableNode>,
queue: Vec<&'a mut BucketTree>,
}
impl<'a> BucketTreeNodeIteratorMut<'a> {
fn new(mut tree: &'a mut BucketTree) -> Self {
let mut queue = Vec::new();
let current = loop {
match &mut tree.data {
BucketTreeNode::Leaf(nodes) => break nodes.iter_mut(),
BucketTreeNode::LeftRight(left, right) => {
queue.push(right.as_mut());
tree = left.as_mut()
}
}
};
BucketTreeNodeIteratorMut { current, queue }
}
}
impl<'a> Iterator for BucketTreeNodeIteratorMut<'a> {
type Item = &'a mut RoutingTableNode;
fn next(&mut self) -> Option<Self::Item> {
if let Some(v) = self.current.next() {
return Some(v);
};
loop {
let tree = self.queue.pop()?;
match &mut tree.data {
BucketTreeNode::Leaf(nodes) => {
self.current = nodes.iter_mut();
match self.current.next() {
Some(v) => return Some(v),
None => continue,
}
}
BucketTreeNode::LeftRight(left, right) => {
self.queue.push(right.as_mut());
self.queue.push(left.as_mut());
continue;
}
}
}
}
}
fn compute_split_start_end(
start: Id20,
end_inclusive: Id20,
bits: u8,
) -> ((Id20, Id20), (Id20, Id20)) {
let changing_bit = 160 - bits;
let new_left_end = {
let mut c = end_inclusive;
c.set_bit(changing_bit, false);
c
};
let new_right_start = {
let mut c = start;
c.set_bit(changing_bit, true);
c
};
debug_assert!(
start < new_left_end,
"expected start({:?}) < new_left_end({:?}); start={:?}, end={:?}, bits={}",
start,
new_left_end,
start,
end_inclusive,
bits
);
debug_assert!(
new_left_end < new_right_start,
"expected new_left_end({:?}) < new_right_start({:?}); start={:?}, end={:?}, bits={}",
new_left_end,
new_right_start,
start,
end_inclusive,
bits
);
debug_assert!(
new_right_start < end_inclusive,
"expected new_right_start({:?}) < end_inclusive({:?}); start={:?}, end={:?}, bits={}",
new_right_start,
end_inclusive,
start,
end_inclusive,
bits
);
((start, new_left_end), (new_right_start, end_inclusive))
}
#[derive(Debug)]
pub enum InsertResult {
WasExisting,
ReplacedBad(RoutingTableNode),
Added,
Ignored,
}
impl BucketTree {
pub fn new() -> Self {
BucketTree {
bits: 160,
start: Id20([0u8; 20]),
end_inclusive: Id20([0xff; 20]),
data: BucketTreeNode::Leaf(Vec::with_capacity(8)),
}
}
pub fn iter(&self) -> BucketTreeNodeIterator<'_> {
BucketTreeNodeIterator::new(self)
}
pub fn iter_mut(&mut self) -> BucketTreeNodeIteratorMut<'_> {
BucketTreeNodeIteratorMut::new(self)
}
pub fn get_mut(&mut self, id: &Id20) -> Option<&mut RoutingTableNode> {
if !(*id >= self.start && *id <= self.end_inclusive) {
return None;
}
match &mut self.data {
BucketTreeNode::Leaf(nodes) => nodes.iter_mut().find(|b| b.id == *id),
BucketTreeNode::LeftRight(left, right) => {
left.get_mut(id).or_else(move || right.get_mut(id))
}
}
}
pub fn add_node(&mut self, self_id: &Id20, id: Id20, addr: SocketAddr) -> InsertResult {
let mut tree = self;
loop {
match &mut tree.data {
BucketTreeNode::Leaf(_) => {
assert!(id >= tree.start && id <= tree.end_inclusive);
return tree.insert_into_leaf(self_id, id, addr);
}
BucketTreeNode::LeftRight(left, right) => {
if id >= right.start {
// Erase lifetime.
// Safety: this is safe as it's a tree, not a DAG or Graph.
tree = unsafe { &mut *(right.as_mut() as *mut _) };
continue;
}
tree = unsafe { &mut *(left.as_mut() as *mut _) };
}
}
}
}
fn insert_into_leaf(&mut self, self_id: &Id20, id: Id20, addr: SocketAddr) -> InsertResult {
let nodes = match &mut self.data {
BucketTreeNode::Leaf(nodes) => nodes,
BucketTreeNode::LeftRight(_, _) => unreachable!(),
};
// if already found, quit
if nodes.iter().any(|r| r.id == id) {
return InsertResult::WasExisting;
}
let mut new_node = RoutingTableNode {
id,
addr,
last_request: None,
last_response: None,
outstanding_queries_in_a_row: 0,
};
if nodes.len() < 8 {
nodes.push(new_node);
nodes.sort_by_key(|n| n.id);
return InsertResult::Added;
}
// Try replace a bad node
if let Some(bad_node) = nodes
.iter_mut()
.find(|r| matches!(r.status(), NodeStatus::Bad))
{
std::mem::swap(bad_node, &mut new_node);
return InsertResult::ReplacedBad(new_node);
}
// if our id is not inside, don't bother.
if *self_id < self.start || *self_id > self.end_inclusive {
return InsertResult::Ignored;
}
// Split
let ((ls, le), (rs, re)) =
compute_split_start_end(self.start, self.end_inclusive, self.bits);
let (mut ld, mut rd) = (Vec::with_capacity(8), Vec::with_capacity(8));
for node in nodes.drain(0..) {
if node.id < rs {
ld.push(node);
} else {
rd.push(node)
}
}
let mut left = BucketTree {
bits: self.bits - 1,
start: ls,
end_inclusive: le,
data: BucketTreeNode::Leaf(ld),
};
let mut right = BucketTree {
bits: self.bits - 1,
start: rs,
end_inclusive: re,
data: BucketTreeNode::Leaf(rd),
};
let result = if id < rs {
left.add_node(self_id, id, addr)
} else {
right.add_node(self_id, id, addr)
};
self.data = BucketTreeNode::LeftRight(Box::new(left), Box::new(right));
result
}
}
impl Default for BucketTree {
fn default() -> Self {
Self::new()
}
}
use crate::id20::Id20;
#[derive(Debug)]
pub struct RoutingTableNode {
id: Id20,
addr: SocketAddr,
last_request: Option<Instant>,
last_response: Option<Instant>,
outstanding_queries_in_a_row: usize,
}
pub enum NodeStatus {
Good,
Questionable,
Bad,
Unknown,
}
impl RoutingTableNode {
pub fn id(&self) -> Id20 {
self.id
}
pub fn addr(&self) -> SocketAddr {
self.addr
}
pub fn status(&self) -> NodeStatus {
// TODO: this is just a stub with simpler logic
let last_request = match self.last_request {
Some(v) => v,
None => return NodeStatus::Unknown,
};
if self.outstanding_queries_in_a_row > 0 && last_request.elapsed() > Duration::from_secs(10)
{
return NodeStatus::Bad;
}
if self.last_response.is_some() {
return NodeStatus::Good;
}
NodeStatus::Questionable
}
pub fn mark_outgoing_request(&mut self) {
self.last_request = Some(Instant::now());
self.outstanding_queries_in_a_row += 1;
}
pub fn mark_response(&mut self) {
self.last_response = Some(Instant::now());
self.outstanding_queries_in_a_row = 0;
}
}
#[derive(Debug)]
pub struct RoutingTable {
id: Id20,
size: usize,
buckets: BucketTree,
}
impl RoutingTable {
pub fn new(id: Id20) -> Self {
Self {
id,
buckets: BucketTree::new(),
size: 0,
}
}
pub fn sorted_by_distance_from(&self, id: Id20) -> Vec<&RoutingTableNode> {
let mut result = Vec::with_capacity(self.size);
for node in self.buckets.iter() {
result.push(node);
}
result.sort_by_key(|n| id.distance(&n.id));
result
}
pub fn sorted_by_distance_from_mut(&mut self, id: Id20) -> Vec<&mut RoutingTableNode> {
let mut result = Vec::with_capacity(self.size);
for node in self.buckets.iter_mut() {
result.push(node);
}
result.sort_by_key(|n| id.distance(&n.id));
result
}
pub fn add_node(&mut self, id: Id20, addr: SocketAddr) -> InsertResult {
let res = self.buckets.add_node(&self.id, id, addr);
let replaced = match &res {
InsertResult::WasExisting => false,
InsertResult::ReplacedBad(_) => true,
InsertResult::Added => true,
InsertResult::Ignored => false,
};
if replaced {
self.size += 1;
}
res
}
pub fn mark_outgoing_request(&mut self, id: &Id20) -> bool {
let r = match self.buckets.get_mut(id) {
Some(r) => r,
None => return false,
};
r.mark_outgoing_request();
true
}
pub fn mark_response(&mut self, id: &Id20) -> bool {
let r = match self.buckets.get_mut(id) {
Some(r) => r,
None => return false,
};
r.mark_response();
true
}
}
#[cfg(test)]
mod tests {
use std::net::SocketAddrV4;
use rand::Rng;
use crate::{id20::Id20, routing_table::compute_split_start_end};
use super::RoutingTable;
#[test]
fn compute_split_start_end_root() {
let start = Id20([0u8; 20]);
let end = Id20([0xff; 20]);
assert_eq!(
compute_split_start_end(start, end, 160),
(
(
start,
Id20([
0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
])
),
(
Id20([
0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
]),
end
)
)
)
}
#[test]
fn compute_split_start_end_second_split() {
let start = Id20([
0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]);
let end = Id20([0xff; 20]);
assert_eq!(
compute_split_start_end(start, end, 159),
(
(
start,
Id20([
0xbf, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
])
),
(
Id20([
0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
]),
end
)
)
)
}
#[test]
fn compute_split_start_end_3() {
let start = Id20([
0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
]);
let end = Id20([0xff; 20]);
assert_eq!(
compute_split_start_end(start, end, 159),
(
(
start,
Id20([
0xbf, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
])
),
(
Id20([
0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
]),
end
)
)
)
}
fn random_id_20() -> Id20 {
let mut id20 = [0u8; 20];
rand::thread_rng().fill(&mut id20);
Id20(id20)
}
#[test]
fn simulate_tree() {
let my_id = random_id_20();
let mut rtable = RoutingTable::new(my_id);
for i in 0..u16::MAX {
let other_id = random_id_20();
let addr = std::net::SocketAddr::V4(SocketAddrV4::new("0.0.0.0".parse().unwrap(), i));
rtable.add_node(other_id, addr);
}
dbg!(&rtable);
assert_eq!(rtable.sorted_by_distance_from(my_id).len(), rtable.size);
}
}