garage/src/table.rs
Alex Auvolat 9c931f5eda Keep network status & ring in a tokio::sync::watch
advantages
- reads don't prevent preparing writes
- can be followed from other parts of the system by cloning the receiver
2020-04-11 23:53:32 +02:00

360 lines
8.7 KiB
Rust

use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;
use async_trait::async_trait;
use futures::stream::*;
use serde::{Deserialize, Serialize};
use serde_bytes::ByteBuf;
use crate::data::*;
use crate::error::Error;
use crate::membership::System;
use crate::proto::*;
use crate::rpc_client::*;
pub struct Table<F: TableFormat> {
pub instance: F,
pub name: String,
pub system: Arc<System>,
pub store: sled::Tree,
pub partitions: Vec<Partition>,
pub param: TableReplicationParams,
}
#[derive(Clone)]
pub struct TableReplicationParams {
pub replication_factor: usize,
pub read_quorum: usize,
pub write_quorum: usize,
pub timeout: Duration,
}
#[async_trait]
pub trait TableRpcHandler {
async fn handle(&self, rpc: &[u8]) -> Result<Vec<u8>, Error>;
}
struct TableRpcHandlerAdapter<F: TableFormat> {
table: Arc<Table<F>>,
}
#[async_trait]
impl<F: TableFormat + 'static> TableRpcHandler for TableRpcHandlerAdapter<F> {
async fn handle(&self, rpc: &[u8]) -> Result<Vec<u8>, Error> {
let msg = rmp_serde::decode::from_read_ref::<_, TableRPC<F>>(rpc)?;
let rep = self.table.handle(msg).await?;
Ok(rmp_to_vec_all_named(&rep)?)
}
}
#[derive(Serialize, Deserialize)]
pub enum TableRPC<F: TableFormat> {
Ok,
ReadEntry(F::P, F::S),
ReadEntryResponse(Option<ByteBuf>),
Update(Vec<Arc<ByteBuf>>),
}
pub struct Partition {
pub begin: Hash,
pub end: Hash,
pub other_nodes: Vec<UUID>,
}
pub trait PartitionKey {
fn hash(&self) -> Hash;
}
pub trait SortKey {
fn sort_key(&self) -> &[u8];
}
pub trait Entry<P: PartitionKey, S: SortKey>:
PartialEq + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync
{
fn partition_key(&self) -> &P;
fn sort_key(&self) -> &S;
fn merge(&mut self, other: &Self);
}
#[derive(Clone, Serialize, Deserialize)]
pub struct EmptySortKey;
impl SortKey for EmptySortKey {
fn sort_key(&self) -> &[u8] {
&[]
}
}
impl<T: AsRef<str>> PartitionKey for T {
fn hash(&self) -> Hash {
hash(self.as_ref().as_bytes())
}
}
impl<T: AsRef<str>> SortKey for T {
fn sort_key(&self) -> &[u8] {
self.as_ref().as_bytes()
}
}
impl PartitionKey for Hash {
fn hash(&self) -> Hash {
self.clone()
}
}
impl SortKey for Hash {
fn sort_key(&self) -> &[u8] {
self.as_slice()
}
}
#[async_trait]
pub trait TableFormat: Send + Sync {
type P: PartitionKey + Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + Send + Sync;
type S: SortKey + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync;
type E: Entry<Self::P, Self::S>;
async fn updated(&self, old: Option<Self::E>, new: Self::E);
}
impl<F: TableFormat + 'static> Table<F> {
pub fn new(
instance: F,
system: Arc<System>,
db: &sled::Db,
name: String,
param: TableReplicationParams,
) -> Self {
let store = db.open_tree(&name).expect("Unable to open DB tree");
Self {
instance,
name,
system,
store,
partitions: Vec::new(),
param,
}
}
pub fn rpc_handler(self: Arc<Self>) -> Box<dyn TableRpcHandler + Send + Sync> {
Box::new(TableRpcHandlerAdapter::<F> { table: self })
}
pub async fn insert(&self, e: &F::E) -> Result<(), Error> {
let hash = e.partition_key().hash();
let who = self
.system
.ring
.borrow()
.clone()
.walk_ring(&hash, self.param.replication_factor);
eprintln!("insert who: {:?}", who);
let e_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(e)?));
let rpc = &TableRPC::<F>::Update(vec![e_enc]);
self.rpc_try_call_many(&who[..], &rpc, self.param.write_quorum)
.await?;
Ok(())
}
pub async fn insert_many(&self, entries: &[F::E]) -> Result<(), Error> {
let mut call_list = HashMap::new();
for entry in entries.iter() {
let hash = entry.partition_key().hash();
let who = self
.system
.ring
.borrow()
.clone()
.walk_ring(&hash, self.param.replication_factor);
let e_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(entry)?));
for node in who {
if !call_list.contains_key(&node) {
call_list.insert(node.clone(), vec![]);
}
call_list.get_mut(&node).unwrap().push(e_enc.clone());
}
}
let call_futures = call_list.drain().map(|(node, entries)| async move {
let rpc = TableRPC::<F>::Update(entries);
let rpc_bytes = rmp_to_vec_all_named(&rpc)?;
let message = Message::TableRPC(self.name.to_string(), rpc_bytes);
let resp = rpc_call(self.system.clone(), &node, &message, self.param.timeout).await?;
Ok::<_, Error>((node, resp))
});
let mut resps = call_futures.collect::<FuturesUnordered<_>>();
let mut errors = vec![];
while let Some(resp) = resps.next().await {
if let Err(e) = resp {
errors.push(e);
}
}
if errors.len() > self.param.replication_factor - self.param.write_quorum {
Err(Error::Message("Too many errors".into()))
} else {
Ok(())
}
}
pub async fn get(&self, partition_key: &F::P, sort_key: &F::S) -> Result<Option<F::E>, Error> {
let hash = partition_key.hash();
let who = self
.system
.ring
.borrow()
.clone()
.walk_ring(&hash, self.param.replication_factor);
eprintln!("get who: {:?}", who);
let rpc = &TableRPC::<F>::ReadEntry(partition_key.clone(), sort_key.clone());
let resps = self
.rpc_try_call_many(&who[..], &rpc, self.param.read_quorum)
.await?;
let mut ret = None;
let mut not_all_same = false;
for resp in resps {
if let TableRPC::ReadEntryResponse(value) = resp {
if let Some(v_bytes) = value {
let v = rmp_serde::decode::from_read_ref::<_, F::E>(v_bytes.as_slice())?;
ret = match ret {
None => Some(v),
Some(mut x) => {
if x != v {
not_all_same = true;
x.merge(&v);
}
Some(x)
}
}
}
} else {
return Err(Error::Message(format!("Invalid return value to read")));
}
}
if let Some(ret_entry) = &ret {
if not_all_same {
let _: Result<_, _> = self.repair_on_read(&who[..], &ret_entry).await;
}
}
Ok(ret)
}
async fn repair_on_read(&self, who: &[UUID], what: &F::E) -> Result<(), Error> {
let what_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(what)?));
self.rpc_try_call_many(&who[..], &TableRPC::<F>::Update(vec![what_enc]), who.len())
.await
.map(|_| ())
}
async fn rpc_try_call_many(
&self,
who: &[UUID],
rpc: &TableRPC<F>,
quorum: usize,
) -> Result<Vec<TableRPC<F>>, Error> {
eprintln!("Table RPC to {:?}: {}", who, serde_json::to_string(&rpc)?);
let rpc_bytes = rmp_to_vec_all_named(rpc)?;
let rpc_msg = Message::TableRPC(self.name.to_string(), rpc_bytes);
let resps = rpc_try_call_many(
self.system.clone(),
who,
&rpc_msg,
quorum,
self.param.timeout,
)
.await?;
let mut resps_vals = vec![];
for resp in resps {
if let Message::TableRPC(tbl, rep_by) = &resp {
if *tbl == self.name {
resps_vals.push(rmp_serde::decode::from_read_ref(&rep_by)?);
continue;
}
}
return Err(Error::Message(format!(
"Invalid reply to TableRPC: {:?}",
resp
)));
}
eprintln!(
"Table RPC responses: {}",
serde_json::to_string(&resps_vals)?
);
Ok(resps_vals)
}
async fn handle(&self, msg: TableRPC<F>) -> Result<TableRPC<F>, Error> {
match msg {
TableRPC::ReadEntry(key, sort_key) => {
let value = self.handle_read_entry(&key, &sort_key)?;
Ok(TableRPC::ReadEntryResponse(value))
}
TableRPC::Update(pairs) => {
self.handle_update(pairs).await?;
Ok(TableRPC::Ok)
}
_ => Err(Error::RPCError(format!("Unexpected table RPC"))),
}
}
fn handle_read_entry(&self, p: &F::P, s: &F::S) -> Result<Option<ByteBuf>, Error> {
let tree_key = self.tree_key(p, s);
if let Some(bytes) = self.store.get(&tree_key)? {
Ok(Some(ByteBuf::from(bytes.to_vec())))
} else {
Ok(None)
}
}
async fn handle_update(&self, mut entries: Vec<Arc<ByteBuf>>) -> Result<(), Error> {
for update_bytes in entries.drain(..) {
let update = rmp_serde::decode::from_read_ref::<_, F::E>(update_bytes.as_slice())?;
let tree_key = self.tree_key(update.partition_key(), update.sort_key());
let (old_entry, new_entry) = self.store.transaction(|db| {
let (old_entry, new_entry) = match db.get(&tree_key)? {
Some(prev_bytes) => {
let old_entry = rmp_serde::decode::from_read_ref::<_, F::E>(&prev_bytes)
.map_err(Error::RMPDecode)
.map_err(sled::ConflictableTransactionError::Abort)?;
let mut new_entry = old_entry.clone();
new_entry.merge(&update);
(Some(old_entry), new_entry)
}
None => (None, update.clone()),
};
let new_bytes = rmp_to_vec_all_named(&new_entry)
.map_err(Error::RMPEncode)
.map_err(sled::ConflictableTransactionError::Abort)?;
db.insert(tree_key.clone(), new_bytes)?;
Ok((old_entry, new_entry))
})?;
self.instance.updated(old_entry, new_entry).await;
}
Ok(())
}
fn tree_key(&self, p: &F::P, s: &F::S) -> Vec<u8> {
let mut ret = p.hash().to_vec();
ret.extend(s.sort_key());
ret
}
}