use lin-kv and gossip to reduce worst-case lag
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Joe Ardent
parent
5f6312dfb8
commit
5e3e269785
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@ -1,75 +1,42 @@
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use std::collections::{BTreeMap, HashMap};
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use nebkor_maelstrom::{mk_payload, Body, Message, Node, Payload, Runner};
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use nebkor_maelstrom::{kv::Kv, mk_payload, Body, Message, Node, Payload, Runner};
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type Logs = HashMap<String, BTreeMap<u64, u64>>;
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fn main() {
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let node = Roach::new(20);
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let node = Roach::default();
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let runner = Runner::new(node);
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let on_init = Box::new(on_init);
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runner.run(Some(on_init));
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}
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fn on_init(runner: &Runner) {
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let msg = Message::from_body(Body::from_type("init_log"));
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let msg = Message::from_body(Body::from_type("do_init"));
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runner.get_backdoor().send(msg).unwrap();
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}
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#[derive(Debug, Default)]
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struct OffsetState {
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last_page: usize,
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current_chapter: usize,
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}
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#[derive(Debug, Default)]
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struct Roach {
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// these first three get written to as messages come in
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logs: Logs,
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state: HashMap<String, OffsetState>,
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committed_offsets: HashMap<String, u64>,
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// these are initialized on init and then just read
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offset_base: usize,
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sub_chapters: usize, // number of nodes
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pages: usize,
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last_offsets: HashMap<String, u64>,
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neighbors: Vec<String>,
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}
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impl Roach {
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pub fn new(pages: usize) -> Self {
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Roach {
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pages,
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..Default::default()
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fn gossip(&self, runner: &Runner, key: &str, val: u64) {
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let offset = self.last_offsets.get(key).unwrap();
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for neighbor in self.neighbors.iter() {
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let payload = mk_payload(&[
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("key", key.into()),
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("value", val.into()),
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("offset", (*offset).into()),
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]);
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let body = Body::from_type("gossip").with_payload(payload);
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runner.send(neighbor, body);
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}
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}
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fn next_offset(&mut self, key: &str) -> u64 {
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let state = self.state.entry(key.to_string()).or_default();
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if state.last_page + 1 < self.pages {
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state.last_page += 1;
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} else {
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state.last_page = 0;
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state.current_chapter += 1;
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}
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let cur_chap = state.current_chapter;
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let offset_base = self.offset_base;
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let start = (offset_base * self.pages) + (cur_chap * (self.pages * self.sub_chapters));
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(start + state.last_page) as u64
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}
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fn init_log(&mut self, runner: &Runner) {
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self.sub_chapters = runner.nodes().len();
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let id = runner.node_id();
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let mut nodes = runner.nodes().to_owned();
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nodes.sort();
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let idx = nodes
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.iter()
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.enumerate()
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.find(|e| e.1.as_str() == id)
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.unwrap()
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.0;
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self.offset_base = idx;
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}
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}
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impl Node for Roach {
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@ -77,21 +44,59 @@ impl Node for Roach {
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let typ = msg.typ();
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match typ {
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"init_log" => {
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self.init_log(runner);
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"do_init" => {
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let id = runner.node_id();
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let nodes = runner
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.nodes()
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.iter()
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.filter(|n| n.as_str() != id)
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.cloned()
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.collect();
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self.neighbors = nodes;
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}
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"gossip" => {
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let offset = msg.body.payload.get("offset").unwrap().as_u64().unwrap();
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let key = msg.body.payload.get("key").unwrap().as_str().unwrap();
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let val = msg.body.payload.get("value").unwrap().as_u64().unwrap();
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self.logs
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.entry(key.to_owned())
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.or_default()
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.entry(offset)
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.or_insert(val);
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let last = self.last_offsets.entry(key.to_string()).or_default();
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*last = offset.max(*last);
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}
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"send" => {
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let key = msg.body.payload.get("key").unwrap().as_str().unwrap();
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let val = msg.body.payload.get("msg").unwrap().as_u64().unwrap();
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let offset = self.next_offset(key);
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let kv = Kv::lin();
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let offset = self.last_offsets.entry(key.to_string()).or_default();
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let mut cur = *offset;
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let mut new = cur + 1;
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loop {
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match kv.cas(runner, key, cur.into(), new.into(), true) {
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Ok(_) => {
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*offset = new;
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break;
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}
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_ => {
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cur = kv.read(runner, key).unwrap().unwrap().as_u64().unwrap();
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new = cur + 1;
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}
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}
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}
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self.logs
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.entry(key.to_string())
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.or_default()
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.entry(offset)
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.entry(*offset)
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.or_insert(val);
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let payload = mk_payload(&[("offset", offset.into())]);
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let payload = mk_payload(&[("offset", (*offset).into())]);
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let body = Body::from_type("send_ok").with_payload(payload);
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self.gossip(runner, key, val);
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runner.reply(&msg, body);
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}
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"poll" => {
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