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|
use super::DirectoryPutter;
use super::DirectoryService;
use crate::proto;
use crate::Error;
use std::collections::{HashSet, VecDeque};
use tracing::{debug_span, instrument, warn};
/// Traverses a [proto::Directory] from the root to the children.
///
/// This is mostly BFS, but directories are only returned once.
pub struct DirectoryTraverser<DS: DirectoryService> {
directory_service: DS,
/// The list of all directories that still need to be traversed. The next
/// element is picked from the front, new elements are enqueued at the
/// back.
worklist_directory_digests: VecDeque<[u8; 32]>,
/// The list of directory digests already sent to the consumer.
/// We omit sending the same directories multiple times.
sent_directory_digests: HashSet<[u8; 32]>,
}
impl<DS: DirectoryService> DirectoryTraverser<DS> {
pub fn with(directory_service: DS, root_directory_digest: &[u8; 32]) -> Self {
Self {
directory_service,
worklist_directory_digests: VecDeque::from([*root_directory_digest]),
sent_directory_digests: HashSet::new(),
}
}
// enqueue all child directory digests to the work queue, as
// long as they're not part of the worklist or already sent.
// This panics if the digest looks invalid, it's supposed to be checked first.
fn enqueue_child_directories(&mut self, directory: &proto::Directory) {
for child_directory_node in &directory.directories {
let child_digest: [u8; 32] = child_directory_node
.digest
.as_slice()
.try_into()
.map_err(|_e| Error::StorageError("invalid digest length".to_string()))
.unwrap();
if self.worklist_directory_digests.contains(&child_digest)
|| self.sent_directory_digests.contains(&child_digest)
{
continue;
}
self.worklist_directory_digests.push_back(child_digest);
}
}
}
impl<DS: DirectoryService> Iterator for DirectoryTraverser<DS> {
type Item = Result<proto::Directory, Error>;
#[instrument(skip_all)]
fn next(&mut self) -> Option<Self::Item> {
// fetch the next directory digest from the top of the work queue.
match self.worklist_directory_digests.pop_front() {
None => None,
Some(current_directory_digest) => {
let current_directory_b64 = data_encoding::BASE64.encode(¤t_directory_digest);
let span = debug_span!("directory.digest", current_directory_b64);
let _ = span.enter();
// look up the directory itself.
let current_directory = match self.directory_service.get(¤t_directory_digest)
{
// if we got it
Ok(Some(current_directory)) => {
// validate, we don't want to send invalid directories.
if let Err(e) = current_directory.validate() {
warn!("directory failed validation: {}", e.to_string());
return Some(Err(Error::StorageError(format!(
"invalid directory: {}",
current_directory_b64
))));
}
current_directory
}
// if it's not there, we have an inconsistent store!
Ok(None) => {
warn!("directory {} does not exist", current_directory_b64);
return Some(Err(Error::StorageError(format!(
"directory {} does not exist",
current_directory_b64
))));
}
Err(e) => {
warn!("failed to look up directory");
return Some(Err(Error::StorageError(format!(
"unable to look up directory {}: {}",
current_directory_b64, e
))));
}
};
// All DirectoryServices MUST validate directory nodes, before returning them out, so we
// can be sure [enqueue_child_directories] doesn't panic.
// enqueue child directories
self.enqueue_child_directories(¤t_directory);
Some(Ok(current_directory))
}
}
}
}
/// This is a simple implementation of a Directory uploader.
/// TODO: verify connectivity? Factor out these checks into generic helpers?
pub struct SimplePutter<DS: DirectoryService> {
directory_service: DS,
last_directory_digest: Option<[u8; 32]>,
}
impl<DS: DirectoryService> SimplePutter<DS> {
pub fn new(directory_service: DS) -> Self {
Self {
directory_service,
last_directory_digest: None,
}
}
}
impl<DS: DirectoryService> DirectoryPutter for SimplePutter<DS> {
fn put(&mut self, directory: proto::Directory) -> Result<(), Error> {
let digest = self.directory_service.put(directory)?;
// track the last directory digest
self.last_directory_digest = Some(digest);
Ok(())
}
/// We need to be mutable here, as that's the signature of the trait.
fn close(&mut self) -> Result<[u8; 32], Error> {
match self.last_directory_digest {
Some(last_digest) => Ok(last_digest),
None => Err(Error::InvalidRequest(
"no directories sent, can't show root digest".to_string(),
)),
}
}
}
|
