table: implement write sets for insert_many

This commit is contained in:
Alex 2023-11-16 16:41:45 +01:00
parent 22f38808e7
commit 3ecd14b9f6
Signed by untrusted user: lx
GPG key ID: 0E496D15096376BE

View file

@ -143,7 +143,7 @@ impl<F: TableSchema, R: TableReplication> Table<F, R> {
self.data.queue_insert(tx, e) self.data.queue_insert(tx, e)
} }
pub async fn insert_many<I, IE>(&self, entries: I) -> Result<(), Error> pub async fn insert_many<I, IE>(self: &Arc<Self>, entries: I) -> Result<(), Error>
where where
I: IntoIterator<Item = IE> + Send + Sync, I: IntoIterator<Item = IE> + Send + Sync,
IE: Borrow<F::E> + Send + Sync, IE: Borrow<F::E> + Send + Sync,
@ -161,52 +161,149 @@ impl<F: TableSchema, R: TableReplication> Table<F, R> {
Ok(()) Ok(())
} }
async fn insert_many_internal<I, IE>(&self, entries: I) -> Result<(), Error> async fn insert_many_internal<I, IE>(self: &Arc<Self>, entries: I) -> Result<(), Error>
where where
I: IntoIterator<Item = IE> + Send + Sync, I: IntoIterator<Item = IE> + Send + Sync,
IE: Borrow<F::E> + Send + Sync, IE: Borrow<F::E> + Send + Sync,
{ {
let mut call_list: HashMap<_, Vec<_>> = HashMap::new(); // The different items will have to be stored on possibly different nodes.
// We will here batch all items into a single request for each concerned
// node, with all of the entries it must store within that request.
// Each entry has to be saved to a specific list of "write sets", i.e. a set
// of node within wich a quorum must be achieved. In normal operation, there
// is a single write set which corresponds to the quorum in the current
// cluster layout, but when the layout is updated, multiple write sets might
// have to be handled at once. Here, since we are sending many entries, we
// will have to handle many write sets in all cases. The algorihtm is thus
// to send one request to each node with all the items it must save,
// and keep track of the OK responses within each write set: if for all sets
// a quorum of nodes has answered OK, then the insert has succeeded and
// consistency properties (read-after-write) are preserved.
// Some code here might feel redundant with RpcHelper::try_write_many_sets,
// but I think deduplicating could lead to more spaghetti instead of
// improving the readability, so I'm leaving as is.
let quorum = self.data.replication.write_quorum();
// Serialize all entries and compute the write sets for each of them.
// In the case of sharded table replication, this also takes an "ack lock"
// to the layout manager to avoid ack'ing newer versions which are not
// taken into account by writes in progress (the ack can happen later, once
// all writes that didn't take the new layout into account are finished).
// These locks are released when entries_vec is dropped, i.e. when this
// function returns.
let mut entries_vec = Vec::new();
for entry in entries.into_iter() { for entry in entries.into_iter() {
let entry = entry.borrow(); let entry = entry.borrow();
let hash = entry.partition_key().hash(); let hash = entry.partition_key().hash();
// TODO: use write sets let write_sets = self.data.replication.write_sets(&hash);
let who = self.data.replication.storage_nodes(&hash);
let e_enc = Arc::new(ByteBuf::from(entry.encode()?)); let e_enc = Arc::new(ByteBuf::from(entry.encode()?));
for node in who { entries_vec.push((write_sets, e_enc));
call_list.entry(node).or_default().push(e_enc.clone()); }
// Compute a deduplicated list of all of the write sets,
// and compute an index from each node to the position of the sets in which
// it takes part, to optimize the detection of a quorum.
let mut write_sets = entries_vec
.iter()
.map(|(wss, _)| wss.as_ref().iter().map(|ws| ws.as_slice()))
.flatten()
.collect::<Vec<&[Uuid]>>();
write_sets.sort();
write_sets.dedup();
let mut write_set_index = HashMap::<&Uuid, Vec<usize>>::new();
for (i, write_set) in write_sets.iter().enumerate() {
for node in write_set.iter() {
write_set_index.entry(node).or_default().push(i);
} }
} }
let call_futures = call_list.drain().map(|(node, entries)| async move { // Build a map of all nodes to the entries that must be sent to that node.
let rpc = TableRpc::<F>::Update(entries); let mut call_list: HashMap<Uuid, Vec<_>> = HashMap::new();
for (write_sets, entry_enc) in entries_vec.iter() {
for write_set in write_sets.as_ref().iter() {
for node in write_set.iter() {
call_list.entry(*node).or_default().push(entry_enc.clone())
}
}
}
let resp = self // Build futures to actually perform each of the corresponding RPC calls
.system let call_count = call_list.len();
.rpc_helper() let call_futures = call_list.into_iter().map(|(node, entries)| {
.call( let this = self.clone();
&self.endpoint, let tracer = opentelemetry::global::tracer("garage");
node, let span = tracer.start(format!("RPC to {:?}", node));
rpc, let fut = async move {
RequestStrategy::with_priority(PRIO_NORMAL), let rpc = TableRpc::<F>::Update(entries);
) let resp = this
.await?; .system
Ok::<_, Error>((node, resp)) .rpc_helper()
.call(
&this.endpoint,
node,
rpc,
RequestStrategy::with_priority(PRIO_NORMAL).with_quorum(quorum),
)
.await;
(node, resp)
};
fut.with_context(Context::current_with_span(span))
}); });
// Run all requests in parallel thanks to FuturesUnordered, and collect results.
let mut resps = call_futures.collect::<FuturesUnordered<_>>(); let mut resps = call_futures.collect::<FuturesUnordered<_>>();
let mut set_counters = vec![(0, 0); write_sets.len()];
let mut successes = 0;
let mut errors = vec![]; let mut errors = vec![];
while let Some(resp) = resps.next().await { while let Some((node, resp)) = resps.next().await {
if let Err(e) = resp { match resp {
errors.push(e); Ok(_) => {
successes += 1;
for set in write_set_index.get(&node).unwrap().iter() {
set_counters[*set].0 += 1;
}
}
Err(e) => {
errors.push(e);
for set in write_set_index.get(&node).unwrap().iter() {
set_counters[*set].1 += 1;
}
}
}
if set_counters.iter().all(|(ok_cnt, _)| *ok_cnt >= quorum) {
// Success
// Continue all other requests in background
tokio::spawn(async move {
resps.collect::<Vec<(Uuid, Result<_, _>)>>().await;
});
return Ok(());
}
if set_counters
.iter()
.enumerate()
.any(|(i, (_, err_cnt))| err_cnt + quorum > write_sets[i].len())
{
// Too many errors in this set, we know we won't get a quorum
break;
} }
} }
if errors.len() > self.data.replication.max_write_errors() {
Err(Error::Message("Too many errors".into())) // Failure, could not get quorum within at least one set
} else { let errors = errors.iter().map(|e| format!("{}", e)).collect::<Vec<_>>();
Ok(()) Err(Error::Quorum(
} quorum,
Some(write_sets.len()),
successes,
call_count,
errors,
))
} }
pub async fn get( pub async fn get(