Work & TODO

This commit is contained in:
Alex Auvolat 2020-04-08 23:47:34 +02:00
parent cc580da0ae
commit a450103ed0
5 changed files with 78 additions and 40 deletions

29
TODO Normal file
View file

@ -0,0 +1,29 @@
Object table
------------
Rename version table to object table
In value handle the different versions
So that the table becomes (bucket, key) -> CRDT(list of versions)
CRDT merge rule:
- keep one complete version (the one with the highest timestamp)
- keep all incomplete versions with timestamps higher than the complete version
Cleanup rule: remove incomplete versions after a given delay (say 24h)
Block table
-----------
Table is version_UUID -> BTreeMap<(offset, block hash)> OR Deleted (= CRDT top)
Block reference table
---------------------
Table is block_Hash + Sort key: version_UUID -> boolean (true when deleted)
Since the hash key is the same as for the blocks themselves,
we can simply consider the updates to this table as events that increase/decrease a reference counter.

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@ -67,6 +67,9 @@ impl FixedBytes32 {
pub fn as_slice_mut(&mut self) -> &mut [u8] {
&mut self.0[..]
}
pub fn to_vec(&self) -> Vec<u8> {
self.0.to_vec()
}
}
pub type UUID = FixedBytes32;

View file

@ -35,9 +35,6 @@ pub enum Error {
#[error(display = "{}", _0)]
BadRequest(String),
#[error(display = "Entry not found")]
NotFound,
#[error(display = "{}", _0)]
Message(String),
}

View file

@ -2,7 +2,6 @@ use std::time::Duration;
use std::sync::Arc;
use serde::{Serialize, Deserialize};
use async_trait::async_trait;
use reduce::Reduce;
use crate::error::Error;
use crate::proto::*;
@ -52,7 +51,10 @@ impl<F: TableFormat + 'static> TableRpcHandler for TableRpcHandlerAdapter<F> {
#[derive(Serialize, Deserialize)]
pub enum TableRPC<F: TableFormat> {
Ok,
Read(Vec<F::K>),
ReadEntry(F::K, Vec<u8>),
ReadEntryResponse(Option<F::V>),
Update(Vec<(F::K, F::V)>),
}
@ -62,18 +64,19 @@ pub struct Partition {
pub other_nodes: Vec<UUID>,
}
pub trait KeyHash {
pub trait TableKey {
fn hash(&self) -> Hash;
}
pub trait ValueMerge {
pub trait TableValue {
fn sort_key(&self) -> Vec<u8>;
fn merge(&mut self, other: &Self);
}
#[async_trait]
pub trait TableFormat: Send + Sync {
type K: Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + KeyHash + Send + Sync;
type V: Clone + Serialize + for<'de> Deserialize<'de> + ValueMerge + Send + Sync;
type K: Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + TableKey + Send + Sync;
type V: Clone + Serialize + for<'de> Deserialize<'de> + TableValue + Send + Sync;
async fn updated(&self, key: &Self::K, old: Option<&Self::V>, new: &Self::V);
}
@ -109,33 +112,34 @@ impl<F: TableFormat + 'static> Table<F> {
Ok(())
}
pub async fn get(&self, k: &F::K) -> Result<F::V, Error> {
pub async fn get(&self, k: &F::K, sort_key: &[u8]) -> Result<Option<F::V>, Error> {
let hash = k.hash();
let who = self.system.members.read().await
.walk_ring(&hash, self.param.replication_factor);
let rpc = &TableRPC::<F>::Read(vec![k.clone()]);
let rpc = &TableRPC::<F>::ReadEntry(k.clone(), sort_key.to_vec());
let resps = self.rpc_try_call_many(&who[..],
&rpc,
self.param.read_quorum)
.await?;
let mut values = vec![];
let mut ret = None;
for resp in resps {
if let TableRPC::Update(mut pairs) = resp {
if pairs.len() == 0 {
continue;
} else if pairs.len() == 1 && pairs[0].0 == *k {
values.push(pairs.drain(..).next().unwrap().1);
continue;
if let TableRPC::ReadEntryResponse(value) = resp {
if let Some(v) = value {
ret = match ret {
None => Some(v),
Some(mut x) => {
x.merge(&v);
Some(x)
}
}
}
} else {
return Err(Error::Message(format!("Invalid return value to read")));
}
return Err(Error::Message(format!("Invalid return value to read")));
}
values.drain(..)
.reduce(|mut x, y| { x.merge(&y); x })
.map(Ok)
.unwrap_or(Err(Error::NotFound))
Ok(ret)
}
async fn rpc_try_call_many(&self, who: &[UUID], rpc: &TableRPC<F>, quorum: usize) -> Result<Vec<TableRPC<F>>, Error> {
@ -163,33 +167,35 @@ impl<F: TableFormat + 'static> Table<F> {
async fn handle(&self, msg: TableRPC<F>) -> Result<TableRPC<F>, Error> {
match msg {
TableRPC::Read(keys) => {
Ok(TableRPC::Update(self.handle_read(&keys)?))
TableRPC::ReadEntry(key, sort_key) => {
let value = self.handle_read_entry(&key, &sort_key)?;
Ok(TableRPC::ReadEntryResponse(value))
}
TableRPC::Update(pairs) => {
self.handle_write(pairs).await?;
self.handle_update(pairs).await?;
Ok(TableRPC::Ok)
}
_ => Err(Error::RPCError(format!("Unexpected table RPC")))
}
}
fn handle_read(&self, keys: &[F::K]) -> Result<Vec<(F::K, F::V)>, Error> {
let mut results = vec![];
for key in keys.iter() {
if let Some(bytes) = self.store.get(&key.hash())? {
let pair = rmp_serde::decode::from_read_ref::<_, (F::K, F::V)>(bytes.as_ref())?;
results.push(pair);
}
fn handle_read_entry(&self, key: &F::K, sort_key: &[u8]) -> Result<Option<F::V>, Error> {
let mut tree_key = key.hash().to_vec();
tree_key.extend(sort_key);
if let Some(bytes) = self.store.get(&tree_key)? {
let (_, v) = rmp_serde::decode::from_read_ref::<_, (F::K, F::V)>(&bytes)?;
Ok(Some(v))
} else {
Ok(None)
}
Ok(results)
}
async fn handle_write(&self, mut pairs: Vec<(F::K, F::V)>) -> Result<(), Error> {
async fn handle_update(&self, mut pairs: Vec<(F::K, F::V)>) -> Result<(), Error> {
for mut pair in pairs.drain(..) {
let hash = pair.0.hash();
let mut tree_key = pair.0.hash().to_vec();
tree_key.extend(pair.1.sort_key());
let old_val = match self.store.get(&hash)? {
let old_val = match self.store.get(&tree_key)? {
Some(prev_bytes) => {
let (_, old_val) = rmp_serde::decode::from_read_ref::<_, (F::K, F::V)>(&prev_bytes)?;
pair.1.merge(&old_val);
@ -199,7 +205,7 @@ impl<F: TableFormat + 'static> Table<F> {
};
let new_bytes = rmp_serde::encode::to_vec_named(&pair)?;
self.store.insert(&hash, new_bytes)?;
self.store.insert(&tree_key, new_bytes)?;
self.instance.updated(&pair.0, old_val.as_ref(), &pair.1).await;
}

View file

@ -37,13 +37,16 @@ pub struct VersionTable {
pub garage: RwLock<Option<Arc<Garage>>>,
}
impl KeyHash for VersionMetaKey {
impl TableKey for VersionMetaKey {
fn hash(&self) -> Hash {
hash(self.bucket.as_bytes())
}
}
impl ValueMerge for VersionMetaValue {
impl TableValue for VersionMetaValue {
fn sort_key(&self) -> Vec<u8> {
vec![]
}
fn merge(&mut self, other: &Self) {
unimplemented!()
}