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//! Contain structs related to making RPCs
use std::sync::Arc;
use std::time::Duration;
use futures::future::join_all;
use futures::stream::futures_unordered::FuturesUnordered;
use futures::stream::StreamExt;
use futures_util::future::FutureExt;
use tokio::select;
pub use netapp::endpoint::{Endpoint, EndpointHandler, Message as Rpc};
use netapp::peering::fullmesh::FullMeshPeeringStrategy;
pub use netapp::proto::*;
pub use netapp::{NetApp, NodeID};
use garage_util::background::BackgroundRunner;
use garage_util::data::Uuid;
use garage_util::error::Error;
const DEFAULT_TIMEOUT: Duration = Duration::from_secs(10);
/// Strategy to apply when making RPC
#[derive(Copy, Clone)]
pub struct RequestStrategy {
/// Max time to wait for reponse
pub rs_timeout: Duration,
/// Min number of response to consider the request successful
pub rs_quorum: Option<usize>,
/// Should requests be dropped after enough response are received
pub rs_interrupt_after_quorum: bool,
/// Request priority
pub rs_priority: RequestPriority,
}
impl RequestStrategy {
/// Create a RequestStrategy with default timeout and not interrupting when quorum reached
pub fn with_priority(prio: RequestPriority) -> Self {
RequestStrategy {
rs_timeout: DEFAULT_TIMEOUT,
rs_quorum: None,
rs_interrupt_after_quorum: false,
rs_priority: prio,
}
}
/// Set quorum to be reached for request
pub fn with_quorum(mut self, quorum: usize) -> Self {
self.rs_quorum = Some(quorum);
self
}
/// Set timeout of the strategy
pub fn with_timeout(mut self, timeout: Duration) -> Self {
self.rs_timeout = timeout;
self
}
/// Set if requests can be dropped after quorum has been reached
/// In general true for read requests, and false for write
pub fn interrupt_after_quorum(mut self, interrupt: bool) -> Self {
self.rs_interrupt_after_quorum = interrupt;
self
}
}
#[derive(Clone)]
pub struct RpcHelper {
pub(crate) fullmesh: Arc<FullMeshPeeringStrategy>,
pub(crate) background: Arc<BackgroundRunner>,
}
impl RpcHelper {
pub async fn call<M, H, S>(
&self,
endpoint: &Endpoint<M, H>,
to: Uuid,
msg: M,
strat: RequestStrategy,
) -> Result<S, Error>
where
M: Rpc<Response = Result<S, Error>>,
H: EndpointHandler<M>,
{
self.call_arc(endpoint, to, Arc::new(msg), strat).await
}
pub async fn call_arc<M, H, S>(
&self,
endpoint: &Endpoint<M, H>,
to: Uuid,
msg: Arc<M>,
strat: RequestStrategy,
) -> Result<S, Error>
where
M: Rpc<Response = Result<S, Error>>,
H: EndpointHandler<M>,
{
let node_id = to.into();
select! {
res = endpoint.call(&node_id, &msg, strat.rs_priority) => Ok(res??),
_ = tokio::time::sleep(strat.rs_timeout) => Err(Error::Timeout),
}
}
pub async fn call_many<M, H, S>(
&self,
endpoint: &Endpoint<M, H>,
to: &[Uuid],
msg: M,
strat: RequestStrategy,
) -> Vec<(Uuid, Result<S, Error>)>
where
M: Rpc<Response = Result<S, Error>>,
H: EndpointHandler<M>,
{
let msg = Arc::new(msg);
let resps = join_all(
to.iter()
.map(|to| self.call_arc(endpoint, *to, msg.clone(), strat)),
)
.await;
to.iter()
.cloned()
.zip(resps.into_iter())
.collect::<Vec<_>>()
}
pub async fn broadcast<M, H, S>(
&self,
endpoint: &Endpoint<M, H>,
msg: M,
strat: RequestStrategy,
) -> Vec<(Uuid, Result<S, Error>)>
where
M: Rpc<Response = Result<S, Error>>,
H: EndpointHandler<M>,
{
let to = self
.fullmesh
.get_peer_list()
.iter()
.map(|p| p.id.into())
.collect::<Vec<_>>();
self.call_many(endpoint, &to[..], msg, strat).await
}
/// Make a RPC call to multiple servers, returning either a Vec of responses, or an error if
/// strategy could not be respected due to too many errors
pub async fn try_call_many<M, H, S>(
&self,
endpoint: &Arc<Endpoint<M, H>>,
to: &[Uuid],
msg: M,
strategy: RequestStrategy,
) -> Result<Vec<S>, Error>
where
M: Rpc<Response = Result<S, Error>> + 'static,
H: EndpointHandler<M> + 'static,
S: Send,
{
let msg = Arc::new(msg);
let mut resp_stream = to
.to_vec()
.into_iter()
.map(|to| {
let self2 = self.clone();
let msg = msg.clone();
let endpoint2 = endpoint.clone();
async move { self2.call_arc(&endpoint2, to, msg, strategy).await }
})
.collect::<FuturesUnordered<_>>();
let mut results = vec![];
let mut errors = vec![];
let quorum = strategy.rs_quorum.unwrap_or(to.len());
while let Some(resp) = resp_stream.next().await {
match resp {
Ok(msg) => {
results.push(msg);
if results.len() >= quorum {
break;
}
}
Err(e) => {
errors.push(e);
}
}
}
if results.len() >= quorum {
// Continue requests in background.
// Continue the remaining requests immediately using tokio::spawn
// but enqueue a task in the background runner
// to ensure that the process won't exit until the requests are done
// (if we had just enqueued the resp_stream.collect directly in the background runner,
// the requests might have been put on hold in the background runner's queue,
// in which case they might timeout or otherwise fail)
if !strategy.rs_interrupt_after_quorum {
let wait_finished_fut = tokio::spawn(async move {
resp_stream.collect::<Vec<_>>().await;
});
self.background.spawn(wait_finished_fut.map(|_| Ok(())));
}
Ok(results)
} else {
let errors = errors.iter().map(|e| format!("{}", e)).collect::<Vec<_>>();
Err(Error::Quorum(results.len(), to.len(), errors))
}
}
}
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