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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
// Tonic generates code that calls clone on an Arc. Allow this here.
// TODO: Remove this once tonic does not produce this code anymore.
#![allow(clippy::clone_on_ref_ptr)]
//! Compute layer client and server.
use std::collections::BTreeMap;
use std::iter;
use async_trait::async_trait;
use differential_dataflow::consolidation::consolidate_updates;
use differential_dataflow::lattice::Lattice;
use mz_repr::{Diff, GlobalId, Row};
use mz_service::client::{GenericClient, Partitionable, PartitionedState};
use mz_service::grpc::{GrpcClient, GrpcServer, ProtoServiceTypes, ResponseStream};
use timely::progress::frontier::{Antichain, MutableAntichain};
use timely::PartialOrder;
use tonic::{Request, Status, Streaming};
use uuid::Uuid;
use crate::metrics::ReplicaMetrics;
use crate::protocol::command::{ComputeCommand, ProtoComputeCommand};
use crate::protocol::response::{
ComputeResponse, PeekResponse, ProtoComputeResponse, SubscribeBatch, SubscribeResponse,
};
use crate::service::proto_compute_server::ProtoCompute;
include!(concat!(env!("OUT_DIR"), "/mz_compute_client.service.rs"));
/// A client to a compute server.
pub trait ComputeClient<T = mz_repr::Timestamp>:
GenericClient<ComputeCommand<T>, ComputeResponse<T>>
{
}
impl<C, T> ComputeClient<T> for C where C: GenericClient<ComputeCommand<T>, ComputeResponse<T>> {}
#[async_trait]
impl<T: Send> GenericClient<ComputeCommand<T>, ComputeResponse<T>> for Box<dyn ComputeClient<T>> {
async fn send(&mut self, cmd: ComputeCommand<T>) -> Result<(), anyhow::Error> {
(**self).send(cmd).await
}
async fn recv(&mut self) -> Result<Option<ComputeResponse<T>>, anyhow::Error> {
(**self).recv().await
}
}
#[derive(Debug, Clone)]
pub enum ComputeProtoServiceTypes {}
impl ProtoServiceTypes for ComputeProtoServiceTypes {
type PC = ProtoComputeCommand;
type PR = ProtoComputeResponse;
type STATS = ReplicaMetrics;
const URL: &'static str = "/mz_compute_client.service.ProtoCompute/CommandResponseStream";
}
pub type ComputeGrpcClient = GrpcClient<ComputeProtoServiceTypes>;
#[async_trait]
impl<F, G> ProtoCompute for GrpcServer<F>
where
F: Fn() -> G + Send + Sync + 'static,
G: ComputeClient + 'static,
{
type CommandResponseStreamStream = ResponseStream<ProtoComputeResponse>;
async fn command_response_stream(
&self,
request: Request<Streaming<ProtoComputeCommand>>,
) -> Result<tonic::Response<Self::CommandResponseStreamStream>, Status> {
self.forward_bidi_stream(request).await
}
}
/// Maintained state for partitioned compute clients.
///
/// This helper type unifies the responses of multiple partitioned workers in order to present as a
/// single worker:
///
/// * It emits `FrontierUpper` responses reporting the minimum/meet of frontiers reported by the
/// individual workers.
/// * It emits `PeekResponse`s and `SubscribeResponse`s reporting the union of the responses
/// received from the workers.
///
/// In the compute communication stack, this client is instantiated several times:
///
/// * One instance on the controller side, dispatching between cluster processes.
/// * One instance in each cluster process, dispatching between timely worker threads.
///
/// Note that because compute commands, except `CreateTimely`, are only sent to the first process,
/// the cluster-side instances of `PartitionedComputeState` are not guaranteed to see all compute
/// commands. Or more specifically: The instance running inside process 0 sees all commands,
/// whereas the instances running inside the other processes only see `CreateTimely`. The
/// `PartitionedComputeState` implementation must be able to cope with this limited visiblity. It
/// does so by performing most of its state management based on observed compute responses rather
/// than commands.
#[derive(Debug)]
pub struct PartitionedComputeState<T> {
/// Number of partitions the state machine represents.
parts: usize,
/// Upper frontiers for indexes and sinks, both collected as a `MutableAntichain` across all
/// partitions and individually listed for each partition.
///
/// Frontier tracking for a collection is initialized when the first `FrontierUpper` response
/// for that collection is received. Frontier tracking is ceased when all shards have reported
/// advancement to the empty frontier.
///
/// The compute protocol requires that shards always emit a `FrontierUpper` response reporting
/// the empty frontier when a collection is dropped. It further requires that no further
/// `FrontierUpper` responses are emitted for a collection after the empty frontier was
/// reported. These properties ensure that a) we always cease frontier tracking for collections
/// that have been dropped and b) frontier tracking for a collection is not re-initialized
/// after it was ceased.
uppers: BTreeMap<GlobalId, (MutableAntichain<T>, Vec<Antichain<T>>)>,
/// Pending responses for a peek; returnable once all are available.
///
/// Tracking of responses for a peek is initialized when the first `PeekResponse` for that peek
/// is received. Once all shards have provided a `PeekResponse`, a unified peek response is
/// emitted and the peek tracking state is dropped again.
///
/// The compute protocol requires that exactly one response is emitted for each peek. This
/// property ensures that a) we can eventually drop the tracking state maintained for a peek
/// and b) we won't re-initialize tracking for a peek we have already served.
peek_responses: BTreeMap<Uuid, BTreeMap<usize, PeekResponse>>,
/// Tracks in-progress `SUBSCRIBE`s, and the stashed rows we are holding back until their
/// timestamps are complete.
///
/// The updates may be `Err` if any of the batches have reported an error, in which case the
/// subscribe is permanently borked.
///
/// Tracking of a subscribe is initialized when the first `SubscribeResponse` for that
/// subscribe is received. Once all shards have emitted an "end-of-subscribe" response the
/// subscribe tracking state is dropped again.
///
/// The compute protocol requires that for a subscribe that shuts down an end-of-subscribe
/// response is emitted:
///
/// * Either a `Batch` response reporting advancement to the empty frontier...
/// * ... or a `DroppedAt` response reporting that the subscribe was dropped before
/// completing.
///
/// The compute protocol further requires that no further `SubscribeResponse`s are emitted for
/// a subscribe after an end-of-subscribe was reported.
///
/// These two properties ensure that a) once a subscribe has shut down, we can eventually drop
/// the tracking state maintained for it and b) we won't re-initialize tracking for a subscribe
/// we have already dropped.
pending_subscribes: BTreeMap<GlobalId, PendingSubscribe<T>>,
}
impl<T> Partitionable<ComputeCommand<T>, ComputeResponse<T>>
for (ComputeCommand<T>, ComputeResponse<T>)
where
T: timely::progress::Timestamp + Lattice,
{
type PartitionedState = PartitionedComputeState<T>;
fn new(parts: usize) -> PartitionedComputeState<T> {
PartitionedComputeState {
parts,
uppers: BTreeMap::new(),
peek_responses: BTreeMap::new(),
pending_subscribes: BTreeMap::new(),
}
}
}
impl<T> PartitionedComputeState<T>
where
T: timely::progress::Timestamp,
{
fn reset(&mut self) {
let PartitionedComputeState {
parts: _,
uppers,
peek_responses,
pending_subscribes,
} = self;
uppers.clear();
peek_responses.clear();
pending_subscribes.clear();
}
/// Observes commands that move past, and prepares state for responses.
pub fn observe_command(&mut self, command: &ComputeCommand<T>) {
if let ComputeCommand::CreateTimely { .. } = command {
self.reset();
} else {
// We are not guaranteed to observe other compute commands than `CreateTimely`. We must
// therefore not add any logic here that relies on doing so.
}
}
fn start_frontier_tracking(&mut self, id: GlobalId) {
let mut frontier = MutableAntichain::new();
// TODO(benesch): fix this dangerous use of `as`.
#[allow(clippy::as_conversions)]
frontier.update_iter(iter::once((T::minimum(), self.parts as i64)));
let part_frontiers = vec![Antichain::from_elem(T::minimum()); self.parts];
let previous = self.uppers.insert(id, (frontier, part_frontiers));
assert!(
previous.is_none(),
"starting frontier tracking for already present identifier {id}"
);
}
fn cease_frontier_tracking(&mut self, id: GlobalId) {
let previous = self.uppers.remove(&id);
assert!(
previous.is_some(),
"ceasing frontier tracking for absent identifier {id}",
);
}
}
impl<T> PartitionedState<ComputeCommand<T>, ComputeResponse<T>> for PartitionedComputeState<T>
where
T: timely::progress::Timestamp + Lattice,
{
fn split_command(&mut self, command: ComputeCommand<T>) -> Vec<Option<ComputeCommand<T>>> {
self.observe_command(&command);
// As specified by the compute protocol:
// * Forward `CreateTimely` commands to all shards.
// * Forward all other commands to the first shard only.
match command {
ComputeCommand::CreateTimely { config, epoch } => {
let timely_cmds = config.split_command(self.parts);
timely_cmds
.into_iter()
.map(|config| Some(ComputeCommand::CreateTimely { config, epoch }))
.collect()
}
command => {
let mut r = vec![None; self.parts];
r[0] = Some(command);
r
}
}
}
fn absorb_response(
&mut self,
shard_id: usize,
message: ComputeResponse<T>,
) -> Option<Result<ComputeResponse<T>, anyhow::Error>> {
match message {
ComputeResponse::FrontierUpper {
id,
upper: new_shard_upper,
} => {
// Initialize frontier tracking state for this collection, if necessary.
if !self.uppers.contains_key(&id) {
self.start_frontier_tracking(id);
}
let (frontier, shard_frontiers) = self.uppers.get_mut(&id).unwrap();
let old_upper = frontier.frontier().to_owned();
let shard_upper = &mut shard_frontiers[shard_id];
frontier.update_iter(shard_upper.iter().map(|t| (t.clone(), -1)));
shard_upper.join_assign(&new_shard_upper);
frontier.update_iter(shard_upper.iter().map(|t| (t.clone(), 1)));
let new_upper = frontier.frontier();
let result = if PartialOrder::less_than(&old_upper.borrow(), &new_upper) {
Some(Ok(ComputeResponse::FrontierUpper {
id,
upper: new_upper.to_owned(),
}))
} else {
None
};
if new_upper.is_empty() {
// All shards have reported advancement to the empty frontier, so we do not
// expect further updates for this collection.
self.cease_frontier_tracking(id);
}
result
}
ComputeResponse::PeekResponse(uuid, response, otel_ctx) => {
// Incorporate new peek responses; awaiting all responses.
let entry = self
.peek_responses
.entry(uuid)
.or_insert_with(Default::default);
let novel = entry.insert(shard_id, response);
assert!(novel.is_none(), "Duplicate peek response");
// We may be ready to respond.
if entry.len() == self.parts {
let mut response = PeekResponse::Rows(Vec::new());
for (_part, r) in std::mem::take(entry).into_iter() {
response = match (response, r) {
(_, PeekResponse::Canceled) => PeekResponse::Canceled,
(PeekResponse::Canceled, _) => PeekResponse::Canceled,
(_, PeekResponse::Error(e)) => PeekResponse::Error(e),
(PeekResponse::Error(e), _) => PeekResponse::Error(e),
(PeekResponse::Rows(mut rows), PeekResponse::Rows(r)) => {
rows.extend(r.into_iter());
PeekResponse::Rows(rows)
}
};
}
self.peek_responses.remove(&uuid);
// We take the otel_ctx from the last peek, but they should all be the same
Some(Ok(ComputeResponse::PeekResponse(uuid, response, otel_ctx)))
} else {
None
}
}
ComputeResponse::SubscribeResponse(id, response) => {
// Initialize tracking for this subscribe, if necessary.
let entry = self
.pending_subscribes
.entry(id)
.or_insert_with(|| PendingSubscribe::new(self.parts));
let emit_response = match response {
SubscribeResponse::Batch(batch) => {
let frontiers = &mut entry.frontiers;
let old_frontier = frontiers.frontier().to_owned();
frontiers.update_iter(batch.lower.into_iter().map(|t| (t, -1)));
frontiers.update_iter(batch.upper.into_iter().map(|t| (t, 1)));
let new_frontier = frontiers.frontier().to_owned();
match (&mut entry.stashed_updates, batch.updates) {
(Err(_), _) => {
// Subscribe is borked; nothing to do.
// TODO: Consider refreshing error?
}
(_, Err(text)) => {
entry.stashed_updates = Err(text);
}
(Ok(stashed_updates), Ok(updates)) => {
stashed_updates.extend(updates);
}
}
// If the frontier has advanced, it is time to announce subscribe progress.
// Unless we have already announced that the subscribe has been dropped, in
// which case we must keep quiet.
if old_frontier != new_frontier && !entry.dropped {
let updates = match &mut entry.stashed_updates {
Ok(stashed_updates) => {
// The compute protocol requires us to only send out
// consolidated batches.
consolidate_updates(stashed_updates);
let mut ship = Vec::new();
let mut keep = Vec::new();
for (time, data, diff) in stashed_updates.drain(..) {
if new_frontier.less_equal(&time) {
keep.push((time, data, diff));
} else {
ship.push((time, data, diff));
}
}
entry.stashed_updates = Ok(keep);
Ok(ship)
}
Err(text) => Err(text.clone()),
};
Some(Ok(ComputeResponse::SubscribeResponse(
id,
SubscribeResponse::Batch(SubscribeBatch {
lower: old_frontier,
upper: new_frontier,
updates,
}),
)))
} else {
None
}
}
SubscribeResponse::DroppedAt(frontier) => {
entry
.frontiers
.update_iter(frontier.iter().map(|t| (t.clone(), -1)));
if entry.dropped {
None
} else {
entry.dropped = true;
Some(Ok(ComputeResponse::SubscribeResponse(
id,
SubscribeResponse::DroppedAt(frontier),
)))
}
}
};
if entry.frontiers.frontier().is_empty() {
// All shards have reported advancement to the empty frontier or dropping, so
// we do not expect further updates for this subscribe.
self.pending_subscribes.remove(&id);
}
emit_response
}
}
}
}
#[derive(Debug)]
struct PendingSubscribe<T> {
/// The subscribe frontiers of the partitioned shards.
frontiers: MutableAntichain<T>,
/// The updates we are holding back until their timestamps are complete.
stashed_updates: Result<Vec<(T, Row, Diff)>, String>,
/// Whether we have already emitted a `DroppedAt` response for this subscribe.
///
/// This field is used to ensure we emit such a response only once.
dropped: bool,
}
impl<T: timely::progress::Timestamp> PendingSubscribe<T> {
fn new(parts: usize) -> Self {
let mut frontiers = MutableAntichain::new();
// TODO(benesch): fix this dangerous use of `as`.
#[allow(clippy::as_conversions)]
frontiers.update_iter([(T::minimum(), parts as i64)]);
Self {
frontiers,
stashed_updates: Ok(Vec::new()),
dropped: false,
}
}
}