use crate::directoryservice::DirectoryService;
use crate::proto;
use data_encoding::BASE64;
use std::collections::{HashMap, HashSet, VecDeque};
use tokio::{sync::mpsc::channel, task};
use tokio_stream::wrappers::ReceiverStream;
use tonic::{async_trait, Request, Response, Status, Streaming};
use tracing::{debug, info_span, instrument, warn};
pub struct GRPCDirectoryServiceWrapper<C: DirectoryService> {
directory_service: C,
}
impl<DS: DirectoryService> From<DS> for GRPCDirectoryServiceWrapper<DS> {
fn from(value: DS) -> Self {
Self {
directory_service: value,
}
}
}
#[async_trait]
impl<DS: DirectoryService + Send + Sync + Clone + 'static>
proto::directory_service_server::DirectoryService for GRPCDirectoryServiceWrapper<DS>
{
type GetStream = ReceiverStream<tonic::Result<proto::Directory, Status>>;
#[instrument(skip(self))]
async fn get(
&self,
request: Request<proto::GetDirectoryRequest>,
) -> Result<Response<Self::GetStream>, Status> {
let (tx, rx) = channel(5);
let req_inner = request.into_inner();
let directory_service = self.directory_service.clone();
// kick off an async thread
task::spawn(async move {
// Keep the list of directory digests to traverse.
// As per rpc_directory.proto, we traverse in BFS order.
let mut deq: VecDeque<[u8; 32]> = VecDeque::new();
// look at the digest in the request and put it in the top of the queue.
match &req_inner.by_what {
None => return Err(Status::invalid_argument("by_what needs to be specified")),
Some(proto::get_directory_request::ByWhat::Digest(digest)) => {
deq.push_back(
digest
.as_slice()
.try_into()
.map_err(|_e| Status::invalid_argument("invalid digest length"))?,
);
}
}
// keep a list of all the Directory messages already sent, so we can omit sending the same.
let mut sent_directory_dgsts: HashSet<[u8; 32]> = HashSet::new();
// look up the directory at the top of the queue
while let Some(digest) = deq.pop_front() {
let digest_b64: String = BASE64.encode(&digest);
// add digest we're currently processing to a span, but pay attention to
// https://docs.rs/tracing/0.1.37/tracing/span/struct.Span.html#in-asynchronous-code
// There may be no await in here (we leave the span before the tx.send(…).await)
let span = info_span!("digest", "{}", &digest_b64);
let res: Result<proto::Directory, Status> = {
let _enter = span.enter();
// invoke client.get, and map to a Result<Directory, Status>
match directory_service.get(&digest) {
// The directory was not found, abort
Ok(None) => {
if !sent_directory_dgsts.is_empty() {
// If this is not the first lookup, we have a
// consistency issue, and we're missing some children, of which we have the
// parents. Log this out.
// Both the node we started with, and the
// current digest are part of the span.
warn!("consistency issue: directory not found")
}
Err(Status::not_found(format!(
"directory {} not found",
digest_b64
)))
}
Ok(Some(directory)) => {
// if recursion was requested, all its children need to be added to the queue.
// If a Directory message with the same digest has already
// been sent previously, we can skip enqueueing it.
// Same applies to when it already is in the queue.
if req_inner.recursive {
for child_directory_node in &directory.directories {
let child_directory_node_digest: [u8; 32] =
child_directory_node.digest.clone().try_into().map_err(
|_e| {
Status::internal(
"invalid child directory digest len",
)
},
)?;
if !sent_directory_dgsts.contains(&child_directory_node_digest)
&& !deq.contains(&child_directory_node_digest)
{
deq.push_back(child_directory_node_digest);
}
}
}
// add it to sent_directory_dgsts.
// Strictly speaking, it wasn't sent yet, but tx.send happens right after,
// and the only way we can still fail is by the remote side to hang up,
// in which case we stop anyways.
sent_directory_dgsts.insert(digest);
Ok(directory)
}
Err(e) => Err(e.into()),
}
};
// send the result to the client
if (tx.send(res).await).is_err() {
debug!("receiver dropped");
break;
}
}
Ok(())
});
// NOTE: this always returns an Ok response, with the first item in the
// stream being a potential error, instead of directly returning the
// first error.
// There's no need to check if the directory node exists twice,
// and client code should consider an Err(), or the first item of the
// stream being an error to be equivalent.
let receiver_stream = ReceiverStream::new(rx);
Ok(Response::new(receiver_stream))
}
#[instrument(skip(self, request))]
async fn put(
&self,
request: Request<Streaming<proto::Directory>>,
) -> Result<Response<proto::PutDirectoryResponse>, Status> {
let mut req_inner = request.into_inner();
// This keeps track of the seen directory keys, and their size.
// This is used to validate the size field of a reference to a previously sent directory.
// We don't need to keep the contents around, they're stored in the DB.
let mut seen_directories_sizes: HashMap<[u8; 32], u32> = HashMap::new();
let mut last_directory_dgst: Option<[u8; 32]> = None;
// Consume directories, and insert them into the store.
// Reject directory messages that refer to Directories not sent in the same stream.
while let Some(directory) = req_inner.message().await? {
// validate the directory itself.
if let Err(e) = directory.validate() {
return Err(Status::invalid_argument(format!(
"directory {} failed validation: {}",
BASE64.encode(&directory.digest()),
e,
)));
}
// for each child directory this directory refers to, we need
// to ensure it has been seen already in this stream, and that the size
// matches what we recorded.
for child_directory in &directory.directories {
let child_directory_digest: [u8; 32] = child_directory
.digest
.clone()
.try_into()
.map_err(|_e| Status::internal("invalid child directory digest len"))?;
match seen_directories_sizes.get(&child_directory_digest) {
None => {
return Err(Status::invalid_argument(format!(
"child directory '{}' ({}) in directory '{}' not seen yet",
child_directory.name,
BASE64.encode(&child_directory_digest),
BASE64.encode(&directory.digest()),
)));
}
Some(seen_child_directory_size) => {
if seen_child_directory_size != &child_directory.size {
return Err(Status::invalid_argument(format!(
"child directory '{}' ({}) in directory '{}' referred with wrong size, expected {}, actual {}",
child_directory.name,
BASE64.encode(&child_directory_digest),
BASE64.encode(&directory.digest()),
seen_child_directory_size,
child_directory.size,
)));
}
}
}
}
// TODO: We don't validate the currently received directory refers
// to at least one child we already received.
// This means, we thoeretically allow uploading multiple disconnected graphs,
// and the digest of the last element in the stream becomes the root node.
// For example, you can upload a leaf directory A, a leaf directory
// B, and then as last element a directory C that only refers to A,
// leaving B disconnected.
// At some point, we might want to populate a datastructure that
// does a reachability check.
let dgst = directory.digest();
seen_directories_sizes.insert(dgst, directory.size());
last_directory_dgst = Some(dgst);
// check if the directory already exists in the database. We can skip
// inserting if it's already there, as that'd be a no-op.
match self.directory_service.get(&dgst) {
Err(e) => {
warn!("error checking if directory already exists: {}", e);
return Err(e.into());
}
// skip if already exists
Ok(Some(_)) => {}
// insert if it doesn't already exist
Ok(None) => {
self.directory_service.put(directory)?;
}
}
}
// We're done receiving. peek at last_directory_digest and either return the digest,
// or an error, if we received an empty stream.
match last_directory_dgst {
None => Err(Status::invalid_argument("no directories received")),
Some(last_directory_dgst) => Ok(Response::new(proto::PutDirectoryResponse {
root_digest: last_directory_dgst.to_vec(),
})),
}
}
}
