Files
crank/crates/crank-artifacts/src/recovery.rs
T

225 lines
8.3 KiB
Rust

use std::{
fmt,
os::fd::{AsRawFd, OwnedFd},
time::{Duration, SystemTime, UNIX_EPOCH},
};
use crate::{
ArtifactError, ArtifactRef, ArtifactStore, ReconciliationCandidate, ReconciliationCursor,
ReconciliationNamespace, ReconciliationPresence, ReconciliationRegistration,
ReconciliationScan,
housekeeping::{ensure_reconciliation_root, revalidate_candidate},
store::{
QUARANTINE_DIR, Root, RootLock, checkpointed, ensure_root_unchanged, open_existing_dir,
open_existing_file, read_verified, stat_fd,
},
};
pub(crate) const FINAL_NAMESPACE: u8 = 0;
pub(crate) const QUARANTINE_NAMESPACE: u8 = 1;
pub(crate) fn namespace_name(namespace: u8) -> &'static [u8] {
match namespace {
FINAL_NAMESPACE => b"sha256",
QUARANTINE_NAMESPACE => QUARANTINE_DIR,
_ => unreachable!("validated reconciliation namespace"),
}
}
pub(crate) fn namespace_number(namespace: ReconciliationNamespace) -> u8 {
match namespace {
ReconciliationNamespace::Final => FINAL_NAMESPACE,
ReconciliationNamespace::Quarantine => QUARANTINE_NAMESPACE,
}
}
impl fmt::Debug for ReconciliationCandidate {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("ReconciliationCandidate(..)")
}
}
impl ReconciliationCandidate {
pub fn namespace(&self) -> ReconciliationNamespace {
self.namespace
}
/// Returns whether the candidate has aged past `grace` at `now`.
///
/// This only reports the timestamp captured by the scanner. Callers that
/// need a registration capability must use [`ArtifactStore::register_reconciliation`],
/// which repeats inode and content validation while holding the store lock.
pub fn is_grace_eligible(&self, grace: Duration, now: SystemTime) -> bool {
let modified = UNIX_EPOCH
.checked_add(Duration::new(
self.modified_seconds.max(0) as u64,
self.modified_nanoseconds.max(0) as u32,
))
.unwrap_or(SystemTime::UNIX_EPOCH);
now.duration_since(modified).is_ok_and(|age| age >= grace)
}
}
impl ArtifactStore {
/// Scans only one reconciliation namespace with a bounded opaque cursor.
///
/// A quarantine scan ends after quarantine and never falls through to
/// final entries, so recovery can finish before the normal final sweep.
pub fn scan_reconciliation_namespace(
&self,
namespace: ReconciliationNamespace,
continuation: Option<ReconciliationCursor>,
scan_budget: usize,
result_limit: usize,
) -> Result<(ReconciliationScan, Vec<ReconciliationCandidate>), ArtifactError> {
self.scan_reconciliation_bounded(
namespace,
namespace,
continuation,
scan_budget,
result_limit,
)
}
/// Streams entries without disclosing paths/digests, with opaque continuation.
pub fn scan_reconciliation(
&self,
continuation: Option<ReconciliationCursor>,
scan_budget: usize,
result_limit: usize,
) -> Result<(ReconciliationScan, Vec<ReconciliationCandidate>), ArtifactError> {
self.scan_reconciliation_bounded(
ReconciliationNamespace::Final,
ReconciliationNamespace::Quarantine,
continuation,
scan_budget,
result_limit,
)
}
/// Revalidates a scanned candidate and mints a registration capability
/// only for a file that is old enough and whose bytes still match its
/// canonical name. The candidate remains usable for a later mutation.
pub fn register_reconciliation(
&self,
candidate: &ReconciliationCandidate,
grace: Duration,
now: SystemTime,
) -> Result<ReconciliationRegistration, ArtifactError> {
let root = self.root()?;
let _lock = RootLock::shared(root)?;
ensure_reconciliation_root(root, candidate)?;
let namespace = namespace_number(candidate.namespace);
let namespace_root = open_existing_dir(root.fd.as_raw_fd(), namespace_name(namespace))?;
let shard = open_existing_dir(namespace_root.as_raw_fd(), candidate.shard.as_bytes())?;
revalidate_candidate(candidate, shard.as_raw_fd())?;
let file = open_existing_file(shard.as_raw_fd(), candidate.name.as_bytes())?;
let stat = stat_fd(file.as_raw_fd())?;
if stat.st_dev != candidate.dev
|| stat.st_ino != candidate.ino
|| stat.st_mtime != candidate.modified_seconds
|| stat.st_mtime_nsec != candidate.modified_nanoseconds
{
return Err(ArtifactError::UnsafeRoot);
}
if !candidate.is_grace_eligible(grace, now) {
return Ok(ReconciliationRegistration::NotEligible);
}
let artifact_ref =
ArtifactRef::from_digest_hex(&candidate.name).map_err(|_| ArtifactError::UnsafeRoot)?;
let bytes = read_verified(&file, &artifact_ref)?;
Ok(ReconciliationRegistration::Registered(
crate::RegisteredArtifact {
artifact_ref,
size_bytes: bytes.len(),
},
))
}
/// Convenience form that uses the current wall clock for grace checks.
pub fn register_reconciliation_candidate(
&self,
candidate: &ReconciliationCandidate,
grace: Duration,
) -> Result<ReconciliationRegistration, ArtifactError> {
self.register_reconciliation(candidate, grace, SystemTime::now())
}
/// Probes final and quarantine for an expired claim without disclosing its
/// physical identity. Quarantine takes precedence over final.
pub fn reconciliation_presence(
&self,
artifact_ref: &ArtifactRef,
) -> Result<ReconciliationPresence, ArtifactError> {
let root = self.root()?;
let _lock = match RootLock::shared(root) {
Ok(lock) => lock,
Err(ArtifactError::Storage) => return Ok(ReconciliationPresence::Retryable),
Err(error) => return Err(error),
};
match ensure_root_unchanged(root) {
Ok(()) => {}
Err(ArtifactError::Storage) => return Ok(ReconciliationPresence::Retryable),
Err(error) => return Err(error),
}
match probe_namespace(root, QUARANTINE_NAMESPACE, artifact_ref) {
Ok(Some(presence)) => return Ok(presence),
Ok(None) => {}
Err(presence) => return Ok(presence),
}
match probe_namespace(root, FINAL_NAMESPACE, artifact_ref) {
Ok(Some(presence)) => Ok(presence),
Ok(None) => Ok(ReconciliationPresence::Absent),
Err(presence) => Ok(presence),
}
}
}
fn probe_namespace(
root: &Root,
namespace: u8,
artifact_ref: &ArtifactRef,
) -> Result<Option<ReconciliationPresence>, ReconciliationPresence> {
let namespace_root = probe_dir(root.fd.as_raw_fd(), namespace_name(namespace))?;
let Some(namespace_root) = namespace_root else {
return Ok(None);
};
let shard = probe_dir(namespace_root.as_raw_fd(), artifact_ref.shard().as_bytes())?;
let Some(shard) = shard else {
return Ok(None);
};
let file = match checkpointed("reconciliation_presence_open", || {
open_existing_file(shard.as_raw_fd(), artifact_ref.digest_hex().as_bytes())
}) {
Ok(fd) => fd,
Err(ArtifactError::NotFound) => return Ok(None),
Err(ArtifactError::Integrity | ArtifactError::UnsafeRoot) => {
return Err(ReconciliationPresence::Unsafe);
}
Err(_) => return Err(ReconciliationPresence::Retryable),
};
match read_verified(&file, artifact_ref) {
Ok(_) => Ok(Some(if namespace == FINAL_NAMESPACE {
ReconciliationPresence::Final
} else {
ReconciliationPresence::Quarantine
})),
Err(ArtifactError::Integrity | ArtifactError::UnsafeRoot) => {
Err(ReconciliationPresence::Unsafe)
}
Err(_) => Err(ReconciliationPresence::Retryable),
}
}
fn probe_dir(parent: i32, name: &[u8]) -> Result<Option<OwnedFd>, ReconciliationPresence> {
match open_existing_dir(parent, name) {
Ok(fd) => Ok(Some(fd)),
Err(ArtifactError::NotFound) => Ok(None),
Err(ArtifactError::UnsafeRoot) => Err(ReconciliationPresence::Unsafe),
Err(_) => Err(ReconciliationPresence::Retryable),
}
}