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//! State helper utility
//!
//! All the methods in this module perform appropriate mistrust checks.
//!
//! All the methods arrange to ensure suitably-finegrained exclusive access.
//! "Read-only" or "shared" mode is not supported.
//!
//! ### Differences from `tor_persist::StorageHandle`
//!
//! * Explicit provision is made for multiple instances of a single facility.
//! For example, multiple hidden services,
//! each with their own state, and own lock.
//!
//! * Locking (via filesystem locks) is mandatory, rather than optional -
//! there is no "shared" mode.
//!
//! * Locked state is represented in the Rust type system.
//!
//! * We don't use traits to support multiple implementations.
//! Platform support would be done in the future with `#[cfg]`.
//! Testing is done by temporary directories (as currently with `tor_persist`).
//!
//! * The serde-based `StorageHandle` requires `&mut` for writing.
//! This ensures proper serialisation of 1. read-modify-write cycles
//! and 2. use of the temporary file.
//! Or to put it another way, we model `StorageHandle`
//! as *containing* a `T` without interior mutability.
//!
//! * There's a way to get a raw directory for filesystem operations
//! (currently, will be used for IPT replay logs).
//!
//! ### Implied filesystem structure
//!
//! ```text
//! STATE_DIR/
//! STATE_DIR/KIND/INSTANCE_ID/
//! STATE_DIR/KIND/INSTANCE_ID/lock
//! STATE_DIR/KIND/INSTANCE_ID/KEY.json
//! STATE_DIR/KIND/INSTANCE_ID/KEY.new
//! STATE_DIR/KIND/INSTANCE_ID/KEY/
//!
//! eg
//!
//! STATE_DIR/hss/allium-cepa.lock
//! STATE_DIR/hss/allium-cepa/ipts.json
//! STATE_DIR/hss/allium-cepa/iptpub.json
//! STATE_DIR/hss/allium-cepa/iptreplay/
//! STATE_DIR/hss/allium-cepa/iptreplay/9aa9517e6901c280a550911d3a3c679630403db1c622eedefbdf1715297f795f.bin
//! ```
//!
// The instance's last modification time (see `purge_instances`) is the mtime of
// the INSTANCE_ID directory. The lockfile mtime is not meaningful.
//
//! (The lockfile is outside the instance directory to facilitate
//! concurrency-correct deletion.)
//!
// Specifically:
//
// The situation where there is only the lockfile, is an out-of-course but legal one.
// Likewise, a lockfile plus a *partially* deleted instance state, is also legal.
// Having an existing directory without associated lockfile is forbidden,
// but if it should occur we handle it properly.
//
//! ### Comprehensive example
//!
//! ```
//! use std::{collections::HashSet, fmt, time::{Duration, SystemTime}};
//! use tor_error::{into_internal, Bug};
//! use tor_persist::slug::SlugRef;
//! use tor_persist::state_dir;
//! use state_dir::{InstanceIdentity, InstancePurgeHandler};
//! use state_dir::{InstancePurgeInfo, InstanceStateHandle, StateDirectory, StorageHandle};
//! #
//! # // fake up some things; we do this rather than using real ones
//! # // since this example will move, with the module, to a lower level crate.
//! # struct OnionService { }
//! # #[derive(derive_more::Display)] struct HsNickname(String);
//! # type Error = anyhow::Error;
//! # mod ipt_mgr { pub mod persist {
//! # #[derive(serde::Serialize, serde::Deserialize)] pub struct StateRecord {}
//! # } }
//!
//! impl InstanceIdentity for HsNickname {
//! fn kind() -> &'static str { "hss" }
//! fn write_identity(&self, f: &mut fmt::Formatter) -> fmt::Result {
//! write!(f, "{self}")
//! }
//! }
//!
//! impl OnionService {
//! fn new(
//! nick: HsNickname,
//! state_dir: &StateDirectory,
//! ) -> Result<Self, Error> {
//! let instance_state = state_dir.acquire_instance(&nick)?;
//! let replay_log_dir = instance_state.raw_subdir("ipt_replay")?;
//! let ipts_storage: StorageHandle<ipt_mgr::persist::StateRecord> =
//! instance_state.storage_handle("ipts")?;
//! // ..
//! # Ok(OnionService { })
//! }
//! }
//!
//! struct PurgeHandler<'h>(&'h HashSet<&'h str>, Duration);
//! impl InstancePurgeHandler for PurgeHandler<'_> {
//! fn kind(&self) -> &'static str {
//! <HsNickname as InstanceIdentity>::kind()
//! }
//! fn name_filter(&mut self, id: &SlugRef) -> state_dir::Result<state_dir::Liveness> {
//! Ok(if self.0.contains(id.as_str()) {
//! state_dir::Liveness::Live
//! } else {
//! state_dir::Liveness::PossiblyUnused
//! })
//! }
//! fn age_filter(&mut self, id: &SlugRef, age: Duration)
//! -> state_dir::Result<state_dir::Liveness>
//! {
//! Ok(if age > self.1 {
//! state_dir::Liveness::PossiblyUnused
//! } else {
//! state_dir::Liveness::Live
//! })
//! }
//! fn dispose(&mut self, _info: &InstancePurgeInfo, handle: InstanceStateHandle)
//! -> state_dir::Result<()> {
//! // here might be a good place to delete keys too
//! handle.purge()
//! }
//! }
//! pub fn expire_hidden_services(
//! state_dir: &StateDirectory,
//! currently_configured_nicks: &HashSet<&str>,
//! retain_for: Duration,
//! ) -> Result<(), Error> {
//! state_dir.purge_instances(
//! SystemTime::now(),
//! &mut PurgeHandler(currently_configured_nicks, retain_for),
//! )?;
//! Ok(())
//! }
//! ```
//!
//! ### Platforms without a filesystem
//!
//! The implementation and (in places) the documentation
//! is in terms of filesystems.
//! But, everything except `InstanceStateHandle::raw_subdir`
//! is abstract enough to implement some other way.
//!
//! If we wish to support such platforms, the approach is:
//!
//! * Decide on an approach for `StorageHandle`
//! and for each caller of `raw_subdir`.
//!
//! * Figure out how the startup code will look.
//! (Currently everything is in terms of `fs_mistrust` and filesystems.)
//!
//! * Provide a version of this module with a compatible API
//! in terms of whatever underlying facilities are available.
//! Use `#[cfg]` to select it.
//! Don't implement `raw_subdir`.
//!
//! * Call sites using `raw_subdir` will no longer compile.
//! Use `#[cfg]` at call sites to replace the `raw_subdir`
//! with whatever is appropriate for the platform.
use std::collections::HashSet;
use std::fmt::{self, Display};
use std::fs;
use std::io;
use std::marker::PhantomData;
use std::path::Path;
use std::sync::Arc;
use std::time::{Duration, SystemTime};
use derive_deftly::{define_derive_deftly, Deftly};
use derive_more::{AsRef, Deref};
use itertools::chain;
use serde::{de::DeserializeOwned, Serialize};
use fs_mistrust::{CheckedDir, Mistrust};
use tor_error::bad_api_usage;
use tor_error::ErrorReport as _;
use tracing::trace;
use crate::err::{Action, ErrorSource, Resource};
use crate::load_store;
use crate::slug::{BadSlug, Slug, SlugRef, TryIntoSlug};
pub use crate::Error;
#[allow(unused_imports)] // Simplifies a lot of references in our docs
use crate::slug;
define_derive_deftly! {
ContainsInstanceStateGuard =
impl<$tgens> ContainsInstanceStateGuard for $ttype where $twheres {
fn raw_lock_guard(&self) -> Arc<LockFileGuard> {
self.flock_guard.clone()
}
}
}
/// Re-export of the lock guard type, as obtained via [`ContainsInstanceStateGuard`]
pub use fslock_guard::LockFileGuard;
use std::result::Result as StdResult;
use std::path::MAIN_SEPARATOR as PATH_SEPARATOR;
/// [`Result`](StdResult) throwing a [`state_dir::Error`](Error)
pub type Result<T> = StdResult<T, Error>;
/// Extension for lockfiles
const LOCK_EXTN: &str = "lock";
/// Suffix for lockfiles, precisely `"." + LOCK_EXTN`
// There's no way to concatenate constant strings with names!
// We could use the const_format crate maybe?
const DOT_LOCK: &str = ".lock";
/// The whole program's state directory
///
/// Representation of `[storage] state_dir` and `permissions`
/// from the Arti configuration.
///
/// This type does not embody any subpaths relating to
/// any particular facility within Arti.
///
/// Constructing a `StateDirectory` may involve filesystem permissions checks,
/// so ideally it would be created once per process for performance reasons.
///
/// Existence of a `StateDirectory` also does not imply exclusive access.
///
/// This type is passed to each facility's constructor;
/// the facility implements [`InstanceIdentity`]
/// and calls [`acquire_instance`](StateDirectory::acquire_instance).
///
/// ### Use for caches
///
/// In principle this type and the methods and subtypes available
/// would be suitable for cache data as well as state data.
///
/// However the locking scheme does not tolerate random removal of files.
/// And cache directories are sometimes configured to point to locations
/// with OS-supplied automatic file cleaning.
/// That would not be correct,
/// since the automatic file cleaner might remove an in-use lockfile,
/// effectively unlocking the instance state
/// even while a process exists that thinks it still has the lock.
#[derive(Debug, Clone)]
pub struct StateDirectory {
/// The actual directory, including mistrust config
dir: CheckedDir,
}
/// An instance of a facility that wants to save persistent state (caller-provided impl)
///
/// Each value of a type implementing `InstanceIdentity`
/// designates a specific instance of a specific facility.
///
/// For example, `HsNickname` implements `state_dir::InstanceIdentity`.
///
/// The kind and identity are [`slug`]s.
pub trait InstanceIdentity {
/// Return the kind. For example `hss` for a Tor Hidden Service.
///
/// This must return a fixed string,
/// since usually all instances represented the same Rust type
/// are also the same kind.
///
/// The returned value must be valid as a [`slug`].
//
// This precludes dynamically chosen instance kind identifiers.
// If we ever want that, we'd need an InstanceKind trait that is implemented
// not for actual instances, but for values representing a kind.
fn kind() -> &'static str;
/// Obtain identity
///
/// The instance identity distinguishes different instances of the same kind.
///
/// For example, for a Tor Hidden Service the identity is the nickname.
///
/// The generated string must be valid as a [`slug`].
/// If it is not, the functions in this module will throw `Bug` errors.
/// (Returning `fmt::Error` will cause a panic, as is usual with the fmt API.)
fn write_identity(&self, f: &mut fmt::Formatter) -> fmt::Result;
}
/// For a facility to be expired using [`purge_instances`](StateDirectory::purge_instances) (caller-provided impl)
///
/// A filter which decides which instances to delete,
/// and deletes them if appropriate.
///
/// See [`purge_instances`](StateDirectory::purge_instances) for full documentation.
pub trait InstancePurgeHandler {
/// What kind to iterate over
fn kind(&self) -> &'static str;
/// Can we tell by its name that this instance is still live ?
fn name_filter(&mut self, identity: &SlugRef) -> Result<Liveness>;
/// Can we tell by recent modification that this instance is still live ?
///
/// Many implementations won't need to use the `identity` parameter.
///
/// ### Concurrency
///
/// The `age` passed to this callback might
/// sometimes not be the most recent modification time of the instance.
/// But. before calling `dispose`, `purge_instances` will call this
/// function at least once with a fully up-to-date modification time.
fn age_filter(&mut self, identity: &SlugRef, age: Duration) -> Result<Liveness>;
/// Decide whether to keep this instance
///
/// When it has made its decision, `dispose` should
/// either call [`delete`](InstanceStateHandle::purge),
/// or simply drop `handle`.
///
/// Called only after `name_filter` and `age_filter`
/// both returned [`Liveness::PossiblyUnused`].
///
/// `info` includes the instance name and other useful information
/// such as the last modification time.
///
/// Note that although the existence of `handle` implies
/// there can be no other `InstanceStateHandle`s for this instance,
/// the last modification time of this instance has *not* been updated,
/// as it would be by [`acquire_instance`](StateDirectory::acquire_instance).
fn dispose(&mut self, info: &InstancePurgeInfo, handle: InstanceStateHandle) -> Result<()>;
}
/// Information about an instance, passed to [`InstancePurgeHandler::dispose`]
#[derive(Debug, Clone, amplify::Getters, AsRef)]
pub struct InstancePurgeInfo<'i> {
/// The instance's identity string
#[as_ref]
identity: &'i SlugRef,
/// When the instance state was last updated, according to the filesystem timestamps
///
/// See `[InstanceStateHandle::purge_instances]`
/// for details of what kinds of events count as modifications.
last_modified: SystemTime,
}
/// Is an instance still relevant?
///
/// Returned by [`InstancePurgeHandler::name_filter`].
///
/// See [`StateDirectory::purge_instances`] for details of the semantics.
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[allow(clippy::exhaustive_enums)] // this is a boolean
pub enum Liveness {
/// This instance is not known to be interesting
///
/// It could be perhaps expired, if it's been long enough
PossiblyUnused,
/// This instance is still wanted
Live,
}
/// Objects that co-own a lock on an instance
///
/// Each type implementing this trait mutually excludes independently-acquired
/// [`InstanceStateHandle`]s, and anything derived from them
/// (including, therefore, `ContainsInstanceStateGuard` implementors
/// with independent provenance.)
pub trait ContainsInstanceStateGuard {
/// Obtain a raw clone of the underlying filesystem lock
///
/// This lock (and clones of it) will mutually exclude
/// re-acquisition of the same instance.
fn raw_lock_guard(&self) -> Arc<LockFileGuard>;
}
/// Instance identity string formatter, type-erased
type InstanceIdWriter<'i> = &'i dyn Fn(&mut fmt::Formatter) -> fmt::Result;
impl StateDirectory {
/// Create a new `StateDirectory` from a directory and mistrust configuration
pub fn new(state_dir: impl AsRef<Path>, mistrust: &Mistrust) -> Result<Self> {
/// Implementation, taking non-generic path
fn inner(path: &Path, mistrust: &Mistrust) -> Result<StateDirectory> {
let resource = || Resource::Directory {
dir: path.to_owned(),
};
let handle_err = |source| Error::new(source, Action::Initializing, resource());
let dir = mistrust
.verifier()
.make_secure_dir(path)
.map_err(handle_err)?;
Ok(StateDirectory { dir })
}
inner(state_dir.as_ref(), mistrust)
}
/// Acquires (creates and locks) a storage for an instance
///
/// Ensures the existence and suitability of a subdirectory named `kind/identity`,
/// and locks it for exclusive access.
pub fn acquire_instance<I: InstanceIdentity>(
&self,
identity: &I,
) -> Result<InstanceStateHandle> {
/// Implementation, taking non-generic values for identity
fn inner(
sd: &StateDirectory,
kind_str: &'static str,
id_writer: InstanceIdWriter,
) -> Result<InstanceStateHandle> {
sd.with_instance_path_pieces(kind_str, id_writer, |kind, id, resource| {
let handle_err =
|action, source: ErrorSource| Error::new(source, action, resource());
// Obtain (creating if necessary) a subdir for a Checked
let make_secure_directory = |parent: &CheckedDir, subdir| {
let resource = || Resource::Directory {
dir: parent.as_path().join(subdir),
};
parent
.make_secure_directory(subdir)
.map_err(|source| Error::new(source, Action::Initializing, resource()))
};
// ---- obtain the lock ----
let kind_dir = make_secure_directory(&sd.dir, kind)?;
let lock_path = kind_dir
.join(format!("{id}.{LOCK_EXTN}"))
.map_err(|source| handle_err(Action::Initializing, source.into()))?;
let flock_guard = match LockFileGuard::try_lock(&lock_path) {
Ok(Some(y)) => {
trace!("locked {lock_path:?}");
y.into()
}
Err(source) => {
trace!("locking {lock_path:?}, error {}", source.report());
return Err(handle_err(Action::Locking, source.into()));
}
Ok(None) => {
trace!("locking {lock_path:?}, in use",);
return Err(handle_err(Action::Locking, ErrorSource::AlreadyLocked));
}
};
// ---- we have the lock, calculate the directory (creating it if need be) ----
let dir = make_secure_directory(&kind_dir, id)?;
touch_instance_dir(&dir)?;
Ok(InstanceStateHandle { dir, flock_guard })
})
}
inner(self, I::kind(), &|f| identity.write_identity(f))
}
/// Given a kind and id, obtain pieces of its path and call a "doing work" callback
///
/// This function factors out common functionality needed by
/// [`StateDirectory::acquire_instance`] and [StateDirectory::instance_peek_storage`],
/// particularly relating to instance kind and id, and errors.
///
/// `kind` and `id` are from an `InstanceIdentity`.
fn with_instance_path_pieces<T>(
self: &StateDirectory,
kind_str: &'static str,
id_writer: InstanceIdWriter,
// fn call(kind: &SlugRef, id: &SlugRef, resource_for_error: &impl Fn) -> _
call: impl FnOnce(&SlugRef, &SlugRef, &dyn Fn() -> Resource) -> Result<T>,
) -> Result<T> {
/// Struct that impls `Display` for formatting an instance id
//
// This exists because we want implementors of InstanceIdentity to be able to
// use write! to format their identity string.
struct InstanceIdDisplay<'i>(InstanceIdWriter<'i>);
impl Display for InstanceIdDisplay<'_> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
(self.0)(f)
}
}
let id_string = InstanceIdDisplay(id_writer).to_string();
// Both we and caller use this for our error reporting
let resource = || Resource::InstanceState {
state_dir: self.dir.as_path().to_owned(),
kind: kind_str.to_string(),
identity: id_string.clone(),
};
let handle_bad_slug = |source| Error::new(source, Action::Initializing, resource());
if kind_str.is_empty() {
return Err(handle_bad_slug(BadSlug::EmptySlugNotAllowed));
}
let kind = SlugRef::new(kind_str).map_err(handle_bad_slug)?;
let id = SlugRef::new(&id_string).map_err(handle_bad_slug)?;
call(kind, id, &resource)
}
/// List the instances of a particular kind
///
/// Returns the instance identities.
///
/// (The implementation lists subdirectories named `kind_*`.)
///
/// Concurrency:
/// An instance which is not being removed or created will be
/// listed (or not) according to whether it's present.
/// But, in the presence of concurrent calls to `acquire_instance` and `delete`
/// on different instances,
/// is not guaranteed to provide a snapshot:
/// serialisation is not guaranteed across different instances.
///
/// It *is* guaranteed to list each instance only once.
pub fn list_instances<I: InstanceIdentity>(&self) -> impl Iterator<Item = Result<Slug>> {
self.list_instances_inner(I::kind())
}
/// List the instances of a kind, where the kind is supplied as a value
///
/// Used by `list_instances` and `purge_instances`.
///
/// *Includes* instances that exists only as a stale lockfile.
#[allow(clippy::blocks_in_conditions)] // TODO #1176 this wants to be global
#[allow(clippy::redundant_closure_call)] // false positive, re handle_err
fn list_instances_inner(&self, kind: &'static str) -> impl Iterator<Item = Result<Slug>> {
// We collect the output into these
let mut out = HashSet::new();
let mut errs = Vec::new();
// Error handling
let resource = || Resource::InstanceState {
state_dir: self.dir.as_path().into(),
kind: kind.into(),
identity: "*".into(),
};
/// `fn handle_err!()(source: impl Into<ErrorSource>) -> Error`
//
// (Generic, so can't be a closure. Uses local bindings, so can't be a fn.)
macro_rules! handle_err { { } => {
|source| Error::new(source, Action::Enumerating, resource())
} }
// Obtain an iterator of Result<DirEntry>
match (|| {
let kind = SlugRef::new(kind).map_err(handle_err!())?;
self.dir.read_directory(kind).map_err(handle_err!())
})() {
Err(e) => errs.push(e),
Ok(ents) => {
for ent in ents {
match ent {
Err(e) => errs.push(handle_err!()(e)),
Ok(ent) => {
// Actually handle a directory entry!
let Some(id) = (|| {
// look for either ID or ID.lock
let id = ent.file_name();
let id = id.to_str()?; // ignore non-UTF-8
let id = id.strip_suffix(DOT_LOCK).unwrap_or(id);
let id = SlugRef::new(id).ok()?; // ignore other things
Some(id.to_owned())
})() else {
continue;
};
out.insert(id);
}
}
}
}
}
chain!(errs.into_iter().map(Err), out.into_iter().map(Ok),)
}
/// Delete instances according to selections made by the caller
///
/// Each instance is considered in three stages.
///
/// Firstly, it is passed to [`name_filter`](InstancePurgeHandler::name_filter).
/// If `name_filter` returns `Live`,
/// further consideration is skipped and the instance is retained.
///
/// Secondly, the last time the instance was written to is determined,
// This must be done with the lock held, for correctness
// but the lock must be acquired in a way that doesn't itself update the modification time.
// On Unix this is straightforward because opening for write doesn't update the mtime.
// If this is hard on another platform, we'll need a separate stamp file updated
// by an explicit Acquire operation.
// This is tested by `test_reset_expiry`.
/// and passed to
/// [`age_filter`](InstancePurgeHandler::age_filter).
/// Again, this might mean ensure the instance is retained.
///
/// Thirdly, the resulting `InstanceStateHandle` is passed to
/// [`dispose`](InstancePurgeHandler::dispose).
/// `dispose` may choose to call `handle.delete()`,
/// or simply drop the handle.
///
/// Concurrency:
/// In the presence of multiple concurrent calls to `acquire_instance` and `delete`:
/// `filter` may be called for an instance which is being created or deleted
/// by another task.
/// `dispose` will be properly serialised with other activities on the same instance,
/// as implied by it receiving an `InstanceStateHandle`.
///
/// The expiry time is reset by calls to `acquire_instance`,
/// `StorageHandle::store` and `InstanceStateHandle::raw_subdir`;
/// it *may* be reset by calls to `StorageHandle::delete`.
///
/// Instances that are currently locked by another task will not be purged,
/// but the expiry time is *not* reset by *unlocking* an instance
/// (dropping the last clone of an `InstanceStateHandle`).
///
/// ### Sequencing of `InstancePurgeHandler` callbacks
///
/// Each instance will be processed
/// (and callbacks made for it) at most once;
/// and calls for different instances will not be interleaved.
///
/// During the processing of a particular instance
/// The callbacks will be made in order,
/// progressing monotonically through the methods in the order listed.
/// But `name_filter` and `age_filter` might each be called
/// more than once for the same instance.
// We don't actually call name_filter more than once.
///
/// Between each stage,
/// the purge implementation may discover that the instance
/// ought not to be processed further.
/// So returning `Liveness::PossiblyUnused` from a filter does not
/// guarantee that the next callback will be made.
pub fn purge_instances(
&self,
now: SystemTime,
filter: &mut (dyn InstancePurgeHandler + '_),
) -> Result<()> {
let kind = filter.kind();
for id in self.list_instances_inner(kind) {
let id = id?;
self.with_instance_path_pieces(kind, &|f| write!(f, "{id}"), |kind, id, resource| {
self.maybe_purge_instance(now, kind, id, resource, filter)
})?;
}
Ok(())
}
/// Consider whether to purge an instance
///
/// Performs all the necessary steps, including liveness checks,
/// passing an InstanceStateHandle to filter.dispose,
/// and deleting stale lockfiles without associated state.
#[allow(clippy::cognitive_complexity)] // splitting this would be more, not less, confusing
fn maybe_purge_instance(
&self,
now: SystemTime,
kind: &SlugRef,
id: &SlugRef,
resource: &dyn Fn() -> Resource,
filter: &mut (dyn InstancePurgeHandler + '_),
) -> Result<()> {
/// If `$l` is `Liveness::Live`, returns early with `Ok(())`.
macro_rules! check_liveness { { $l:expr } => {
match $l {
Liveness::Live => return Ok(()),
Liveness::PossiblyUnused => {},
}
} }
check_liveness!(filter.name_filter(id)?);
let dir_path = self.dir.as_path().join(kind).join(id);
// Checks whether it should be kept due to being recently modified.
// None::<SystemTime> means the instance directory is ENOENT
// (which must mean that the instance exists only as a stale lockfile).
let mut age_check = || -> Result<(Liveness, Option<SystemTime>)> {
let handle_io_error = |source| Error::new(source, Action::Enumerating, resource());
// 1. stat the instance dir
let md = match fs::metadata(&dir_path) {
// If instance dir is ENOENT, treat as old (maybe there was just a lockfile)
Err(e) if e.kind() == io::ErrorKind::NotFound => {
return Ok((Liveness::PossiblyUnused, None))
}
other => other.map_err(handle_io_error)?,
};
let mtime = md.modified().map_err(handle_io_error)?;
// 2. calculate the age
let age = now.duration_since(mtime).unwrap_or(Duration::ZERO);
// 3. do the age check
let liveness = filter.age_filter(id, age)?;
Ok((liveness, Some(mtime)))
};
// preliminary check, without locking yet
check_liveness!(age_check()?.0);
// ok we're probably doing to pass it to dispose (for possible deletion)
let lock_path = dir_path.with_extension(LOCK_EXTN);
let flock_guard = match LockFileGuard::try_lock(&lock_path) {
Ok(Some(y)) => {
trace!("locked {lock_path:?} (for purge)");
y
}
Err(source) if source.kind() == io::ErrorKind::NotFound => {
// We couldn't open the lockfile due to ENOENT
// (Presumably) a containing directory is gone, so we don't need to do anything.
trace!("locking {lock_path:?} (for purge), not found");
return Ok(());
}
Ok(None) => {
// Someone else has it locked. Skip purging it.
trace!("locking {lock_path:?} (for purge), in use");
return Ok(());
}
Err(source) => {
trace!(
"locking {lock_path:?} (for purge), error {}",
source.report()
);
return Err(Error::new(source, Action::Locking, resource()));
}
};
// recheck to see if anyone has updated it
let (age, mtime) = age_check()?;
check_liveness!(age);
// We have locked it and the filters say to maybe purge it.
match mtime {
None => {
// And it doesn't even exist! All we have is a leftover lockfile. Delete it.
let lockfile_rsrc = || Resource::File {
container: lock_path.parent().expect("no /!").into(),
file: lock_path.file_name().expect("no /!").into(),
};
flock_guard
.delete_lock_file(&lock_path)
.map_err(|source| Error::new(source, Action::Deleting, lockfile_rsrc()))?;
}
Some(last_modified) => {
// Construct a state handle.
let dir = self
.dir
.make_secure_directory(format!("{kind}/{id}"))
.map_err(|source| Error::new(source, Action::Enumerating, resource()))?;
let flock_guard = Arc::new(flock_guard);
filter.dispose(
&InstancePurgeInfo {
identity: id,
last_modified,
},
InstanceStateHandle { dir, flock_guard },
)?;
}
}
Ok(())
}
/// Tries to peek at something written by [`StorageHandle::store`]
///
/// It is guaranteed that this will return either the `T` that was stored,
/// or `None` if `store` was never called,
/// or `StorageHandle::delete` was called
///
/// So the operation is atomic, but there is no further synchronisation.
//
// Not sure if we need this, but it's logically permissible
pub fn instance_peek_storage<I: InstanceIdentity, T: DeserializeOwned>(
&self,
identity: &I,
key: &(impl TryIntoSlug + ?Sized),
) -> Result<Option<T>> {
self.with_instance_path_pieces(
I::kind(),
&|f| identity.write_identity(f),
// This closure is generic over T, so with_instance_path_pieces will be too;
// this isn't desirable (code bloat) but avoiding it would involves some contortions.
|kind_slug: &SlugRef, id_slug: &SlugRef, _resource| {
// Throwing this error here will give a slightly wrong Error for this Bug
// (because with_instance_path_pieces has its own notion of Action & Resource)
// but that seems OK.
let key_slug = key.try_into_slug()?;
let rel_fname = format!(
"{}{PATH_SEPARATOR}{}{PATH_SEPARATOR}{}.json",
kind_slug, id_slug, key_slug,
);
let target = load_store::Target {
dir: &self.dir,
rel_fname: rel_fname.as_ref(),
};
target
.load()
// This Resource::File isn't consistent with those from StorageHandle:
// StorageHandle's `container` is the instance directory;
// here `container` is the top-level `state_dir`,
// and `file` is `KIND+INSTANCE/STORAGE.json".
.map_err(|source| {
Error::new(
source,
Action::Loading,
Resource::File {
container: self.dir.as_path().to_owned(),
file: rel_fname.into(),
},
)
})
},
)
}
}
/// State or cache directory for an instance of a facility
///
/// Implies exclusive access:
/// there is only one `InstanceStateHandle` at a time,
/// across any number of processes, tasks, and threads,
/// for the same instance.
///
/// # Key uniqueness and syntactic restrictions
///
/// Methods on `InstanceStateHandle` typically take a [`TryIntoSlug`].
///
/// **It is important that keys are distinct within an instance.**
///
/// Specifically:
/// each key provided to a method on the same [`InstanceStateHandle`]
/// (or a clone of it)
/// must be different.
/// Violating this rule does not result in memory-unsafety,
/// but might result in incorrect operation due to concurrent filesystem access,
/// including possible data loss and corruption.
/// (Typically, the key is fixed, and the [`StorageHandle`]s are usually
/// obtained during instance construction, so ensuring this is straightforward.)
///
/// There are also syntactic restrictions on keys. See [slug].
// We could implement a runtime check for this by retaining a table of in-use keys,
// possibly only with `cfg(debug_assertions)`. However I think this isn't worth the code:
// it would involve an Arc<Mutex<SlugsInUseTable>> in InstanceStateHnndle and StorageHandle,
// and Drop impls to remove unused entries (and `raw_subdir` would have imprecise checking
// unless it returned a Drop newtype around CheckedDir).
#[derive(Debug, Clone, Deftly)]
#[derive_deftly(ContainsInstanceStateGuard)]
pub struct InstanceStateHandle {
/// The directory
dir: CheckedDir,
/// Lock guard
flock_guard: Arc<LockFileGuard>,
}
impl InstanceStateHandle {
/// Obtain a [`StorageHandle`], usable for storing/retrieving a `T`
///
/// [`key` has syntactic and uniqueness restrictions.](InstanceStateHandle#key-uniqueness-and-syntactic-restrictions)
pub fn storage_handle<T>(&self, key: &(impl TryIntoSlug + ?Sized)) -> Result<StorageHandle<T>> {
/// Implementation, not generic over `slug` and `T`
fn inner(
ih: &InstanceStateHandle,
key: StdResult<Slug, BadSlug>,
) -> Result<(CheckedDir, String, Arc<LockFileGuard>)> {
let key = key?;
let instance_dir = ih.dir.clone();
let leafname = format!("{key}.json");
let flock_guard = ih.flock_guard.clone();
Ok((instance_dir, leafname, flock_guard))
}
let (instance_dir, leafname, flock_guard) = inner(self, key.try_into_slug())?;
Ok(StorageHandle {
instance_dir,
leafname,
marker: PhantomData,
flock_guard,
})
}
/// Obtain a raw filesystem subdirectory, within the directory for this instance
///
/// This API is unsuitable platforms without a filesystem accessible via `std::fs`.
/// May therefore only be used within Arti for features
/// where we're happy to not to support such platforms (eg WASM without WASI)
/// without substantial further work.
///
/// [`key` has syntactic and uniqueness restrictions.](InstanceStateHandle#key-uniqueness-and-syntactic-restrictions)
pub fn raw_subdir(&self, key: &(impl TryIntoSlug + ?Sized)) -> Result<InstanceRawSubdir> {
/// Implementation, not generic over `slug`
fn inner(
ih: &InstanceStateHandle,
key: StdResult<Slug, BadSlug>,
) -> Result<InstanceRawSubdir> {
let key = key?;
let irs = (|| {
trace!("ensuring/using {:?}/{:?}", ih.dir.as_path(), key.as_str());
let dir = ih.dir.make_secure_directory(&key)?;
let flock_guard = ih.flock_guard.clone();
Ok::<_, ErrorSource>(InstanceRawSubdir { dir, flock_guard })
})()
.map_err(|source| {
Error::new(
source,
Action::Initializing,
Resource::Directory {
dir: ih.dir.as_path().join(key),
},
)
})?;
touch_instance_dir(&ih.dir)?;
Ok(irs)
}
inner(self, key.try_into_slug())
}
/// Unconditionally delete this instance directory
///
/// For expiry, use `StateDirectory::purge_instances`,
/// and then call this in the `dispose` method.
///
/// Will return a `BadAPIUsage` if other clones of this `InstanceStateHandle` exist.
///
/// ### Deletion is *not* atomic
///
/// If a deletion operation doesn't complete for any reason
/// (maybe it was interrupted, or there was a filesystem access problem),
/// *part* of the instance contents may remain.
///
/// After such an interrupted deletion,
/// storage items ([`StorageHandle`]) are might each independently
/// be deleted ([`load`](StorageHandle::load) returns `None`)
/// or retained (`Some`).
///
/// Deletion of the contents of raw subdirectories
/// ([`InstanceStateHandle::raw_subdir`])
/// is done with `std::fs::remove_dir_all`.
/// If deletion is interrupted, the raw subdirectory may contain partial contents.
//
// In principle we could provide atomic deletion, but it would lead to instances
// that were in "limbo": they exist, but wouldn't appear in list_instances,
// and the deletion would need to be completed next time they were acquired
// (or during a purge_instances run).
//
// In practice we expect that callers will not try to use a partially-deleted instance,
// and that if they do they will fail with a "state corrupted" error, which would be fine.
pub fn purge(self) -> Result<()> {
let dir = self.dir.as_path();
(|| {
// use Arc::into_inner on the lock object,
// to make sure we're actually the only surviving InstanceStateHandle
let flock_guard = Arc::into_inner(self.flock_guard).ok_or_else(|| {
bad_api_usage!(
"InstanceStateHandle::purge called for {:?}, but other clones of the handle exist",
self.dir.as_path(),
)
})?;
trace!("purging {:?} (and {})", dir, DOT_LOCK);
fs::remove_dir_all(dir)?;
flock_guard.delete_lock_file(
// dir.with_extension is right because the last component of dir
// is KIND+ID which doesn't contain `.` so no extension will be stripped
dir.with_extension(LOCK_EXTN),
)?;
Ok::<_, ErrorSource>(())
})()
.map_err(|source| {
Error::new(
source,
Action::Deleting,
Resource::Directory { dir: dir.into() },
)
})
}
}
/// Touch an instance the state directory, `dir`, for expiry purposes
fn touch_instance_dir(dir: &CheckedDir) -> Result<()> {
let dir = dir.as_path();
let resource = || Resource::Directory { dir: dir.into() };
filetime::set_file_mtime(dir, filetime::FileTime::now())
.map_err(|source| Error::new(source, Action::Initializing, resource()))
}
/// A place in the state or cache directory, where we can load/store a serialisable type
///
/// Implies exclusive access.
///
/// Rust mutability-xor-sharing rules enforce proper synchronisation,
/// unless multiple `StorageHandle`s are created
/// using the same [`InstanceStateHandle`] and key.
#[derive(Deftly, Debug)] // not Clone, to enforce mutability rules (see above)
#[derive_deftly(ContainsInstanceStateGuard)]
pub struct StorageHandle<T> {
/// The directory and leafname
instance_dir: CheckedDir,
/// `KEY.json`
leafname: String,
/// We can load and store a `T`.
///
/// Invariant in `T`. But we're `Sync` and `Send` regardless of `T`.
/// (From the Table of PhantomData patterns in the Nomicon.)
marker: PhantomData<fn(T) -> T>,
/// Clone of the InstanceStateHandle's lock
flock_guard: Arc<LockFileGuard>,
}
// Like tor_persist, but writing needs `&mut`
impl<T: Serialize + DeserializeOwned> StorageHandle<T> {
/// Load this persistent state
///
/// `None` means the state was most recently [`delete`](StorageHandle::delete)ed
pub fn load(&self) -> Result<Option<T>> {
self.with_load_store_target(Action::Loading, |t| t.load())
}
/// Store this persistent state
pub fn store(&mut self, v: &T) -> Result<()> {
// The renames will cause a directory mtime update
self.with_load_store_target(Action::Storing, |t| t.store(v))
}
/// Delete this persistent state
pub fn delete(&mut self) -> Result<()> {
// Only counts as a recent modification if this state *did* exist
self.with_load_store_target(Action::Deleting, |t| t.delete())
}
/// Operate using a `load_store::Target`
fn with_load_store_target<R, F>(&self, action: Action, f: F) -> Result<R>
where
F: FnOnce(load_store::Target<'_>) -> std::result::Result<R, ErrorSource>,
{
f(load_store::Target {
dir: &self.instance_dir,
rel_fname: self.leafname.as_ref(),
})
.map_err(self.map_err(action))
}
/// Helper to convert an `ErrorSource` to an `Error`, if we were performing `action`
fn map_err(&self, action: Action) -> impl FnOnce(ErrorSource) -> Error {
let resource = self.err_resource();
move |source| crate::Error::new(source, action, resource)
}
/// Return the proper `Resource` for reporting errors
fn err_resource(&self) -> Resource {
Resource::File {
// TODO ideally we would remember what proportion of instance_dir
// came from the original state_dir, so we can put state_dir in the container
container: self.instance_dir.as_path().to_owned(),
file: self.leafname.clone().into(),
}
}
}
/// Subdirectory within an instance's state, for raw filesystem operations
///
/// Dereferences to `fs_mistrust::CheckedDir` and can be used mostly like one.
/// Obtained from [`InstanceStateHandle::raw_subdir`].
///
/// Existence of this value implies exclusive access to the instance.
///
/// If you need to manage the lock, and the directory path, separately,
/// [`raw_lock_guard`](ContainsInstanceStateGuard::raw_lock_guard)
/// will help.
#[derive(Deref, Clone, Debug, Deftly)]
#[derive_deftly(ContainsInstanceStateGuard)]
pub struct InstanceRawSubdir {
/// The actual directory, as a [`fs_mistrust::CheckedDir`]
#[deref]
dir: CheckedDir,
/// Clone of the InstanceStateHandle's lock
flock_guard: Arc<LockFileGuard>,
}
#[cfg(test)]
mod test {
// @@ begin test lint list maintained by maint/add_warning @@
#![allow(clippy::bool_assert_comparison)]
#![allow(clippy::clone_on_copy)]
#![allow(clippy::dbg_macro)]
#![allow(clippy::mixed_attributes_style)]
#![allow(clippy::print_stderr)]
#![allow(clippy::print_stdout)]
#![allow(clippy::single_char_pattern)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::unchecked_duration_subtraction)]
#![allow(clippy::useless_vec)]
#![allow(clippy::needless_pass_by_value)]
//! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
use super::*;
use derive_deftly::{derive_deftly_adhoc, Deftly};
use itertools::{iproduct, Itertools};
use serde::{Deserialize, Serialize};
use std::collections::BTreeSet;
use std::fmt::Display;
use std::fs::File;
use std::io;
use std::str::FromStr;
use test_temp_dir::test_temp_dir;
use tor_basic_utils::PathExt as _;
use tor_error::HasKind as _;
use tracing_test::traced_test;
use tor_error::ErrorKind as TEK;
type AgeDays = i8;
fn days(days: AgeDays) -> Duration {
Duration::from_secs(86400 * u64::try_from(days).unwrap())
}
fn now() -> SystemTime {
SystemTime::now()
}
struct Garlic(Slug);
impl InstanceIdentity for Garlic {
fn kind() -> &'static str {
"garlic"
}
fn write_identity(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.0, f)
}
}
#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
struct StoredData {
some_value: i32,
}
fn mk_state_dir(dir: &Path) -> StateDirectory {
StateDirectory::new(
dir,
&fs_mistrust::Mistrust::new_dangerously_trust_everyone(),
)
.unwrap()
}
#[test]
#[traced_test]
fn test_api() {
test_temp_dir!().used_by(|dir| {
let sd = mk_state_dir(dir);
let garlic = Garlic("wild".try_into_slug().unwrap());
let acquire_instance = || sd.acquire_instance(&garlic);
let ih = acquire_instance().unwrap();
let inst_path = dir.join("garlic/wild");
assert!(fs::metadata(&inst_path).unwrap().is_dir());
assert_eq!(
acquire_instance().unwrap_err().kind(),
TEK::LocalResourceAlreadyInUse,
);
let irsd = ih.raw_subdir("raw").unwrap();
assert!(fs::metadata(irsd.as_path()).unwrap().is_dir());
assert_eq!(irsd.as_path(), dir.join("garlic").join("wild").join("raw"));
let mut sh = ih.storage_handle::<StoredData>("stored_data").unwrap();
let storage_path = dir.join("garlic/wild/stored_data.json");
let peek = || sd.instance_peek_storage(&garlic, "stored_data");
let expect_load = |sh: &StorageHandle<_>, expect| {
let check_loaded = |what, loaded: Result<Option<StoredData>>| {
assert_eq!(loaded.unwrap().as_ref(), expect, "{what}");
};
check_loaded("load", sh.load());
check_loaded("peek", peek());
};
expect_load(&sh, None);
let to_store = StoredData { some_value: 42 };
sh.store(&to_store).unwrap();
assert!(fs::metadata(storage_path).unwrap().is_file());
expect_load(&sh, Some(&to_store));
sh.delete().unwrap();
expect_load(&sh, None);
drop(sh);
drop(irsd);
ih.purge().unwrap();
assert_eq!(peek().unwrap(), None);
assert_eq!(
fs::metadata(&inst_path).unwrap_err().kind(),
io::ErrorKind::NotFound
);
});
}
#[test]
#[traced_test]
#[allow(clippy::comparison_chain)]
#[allow(clippy::expect_fun_call)]
fn test_iter() {
// Tests list_instances and purge_instances.
//
// 1. Set up a single state directory containing a number of instances,
// enumerating all the possible situations that purge_instance might find.
// The instance is identified by a `Which` which specifies its properties,
// and which is representable as the instance id slug.
// 1b. Put some junk in the state directory too, that we expect to be ignored.
//
// 2. Call list_instances and check that we see what we expect.
//
// 3. Call purge_instances and check that all the callbacks happen as we expect.
//
// 4. Call list_instances again and check that we see what we now expect.
//
// 5. Check that the junk is still present.
let temp_dir = test_temp_dir!();
let state_dir = temp_dir.used_by(mk_state_dir);
/// Reified test case spec for expiry
//
// For non-`bool` fields, `#[deftly(test = )]` gives the set of values to test.
#[derive(Deftly, Eq, PartialEq, Debug)]
#[derive_deftly_adhoc]
struct Which {
/// Does `name_filter` return `Live`?
namefilter_live: bool,
/// What is the oldest does `age_filter` will return `Live` for?
#[deftly(test = "0, 2")]
max_age: AgeDays,
/// How long ago was the instance dir actually modified?
#[deftly(test = "-1, 1, 3")]
age: AgeDays,
/// Does the instance dir exist?
dir: bool,
/// Does the instance !lockfile exist?
lockfile: bool,
}
/// Ad-hoc (de)serialisation scheme of `Which` as an instance id (a `Slug`)
///
/// The serialisation is `n<namefilter_live>_m<max_age>_...`,
/// ie, for each field, the initial letter of its name, followed by the value.
/// (We don't bother suppressing the trailiong `_`).
impl Display for Which {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
derive_deftly_adhoc! {
Which:
$(
write!(
f, "{}{}_",
stringify!($fname).chars().next().unwrap(),
self.$fname,
)?;
)
}
Ok(())
}
}
impl FromStr for Which {
type Err = Error;
fn from_str(s: &str) -> Result<Self> {
let mut fields = s.split('_');
derive_deftly_adhoc! {
Which:
Ok(Which { $(
$fname: fields.next().unwrap()
.split_at(1).1
.parse().unwrap(),
)})
}
}
}
impl InstanceIdentity for Which {
fn kind() -> &'static str {
"which"
}
fn write_identity(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(self, f)
}
}
// 0. Calculate all possible whiches
let whiches = {
derive_deftly_adhoc!(
Which:
iproduct!(
$(
${if fmeta(test) { [ ${fmeta(test)} ] } else { [false, true] }},
)
// iproduct hates a trailing comma, so add a dummy element
// https://github.com/rust-itertools/itertools/issues/868
[()]
)
)
.map(derive_deftly_adhoc!(
Which:
//
|($( $fname, ) ())| Which { $( $fname, ) }
))
// if you want to debug one test case, you can do this:
// .filter(|wh| wh.to_string() == "nfalse_r2_a3_lfalse_dtrue_")
.collect_vec()
};
// 1. Create all the test instances, according to the specifications
for which in &whiches {
let s = which.to_string();
println!("{s}");
assert_eq!(&s.parse::<Which>().unwrap(), which);
let inst = state_dir.acquire_instance(which).unwrap();
if !which.dir {
fs::remove_dir_all(inst.dir.as_path()).unwrap();
} else {
let now = now();
let set_mtime = |mtime: SystemTime| {
filetime::set_file_mtime(inst.dir.as_path(), mtime.into()).unwrap();
};
if which.age > 0 {
set_mtime(now - days(which.age));
} else if which.age < 0 {
set_mtime(now + days(-which.age));
};
}
if !which.lockfile {
let lock_path = inst.dir.as_path().with_extension(LOCK_EXTN);
let flock_guard = Arc::into_inner(inst.flock_guard).unwrap();
flock_guard
.delete_lock_file(&lock_path)
.expect(&lock_path.display_lossy().to_string());
}
}
// 1b. Create some junk that should be ignored
let junk = {
let mut junk = Vec::new();
let base = state_dir.dir.as_path();
for rhs in ["+bad", &format!("+bad{DOT_LOCK}"), ".tmp"] {
let mut mk = |lhs, is_dir| {
let p = base.join(format!("{lhs}{rhs}"));
junk.push((p.clone(), is_dir));
p
};
File::create(mk("file", false)).unwrap();
fs::create_dir(mk("dir", true)).unwrap();
}
junk
};
// 2. Check that we see the ones we expect
let list_instances = || {
state_dir
.list_instances::<Which>()
.map(Result::unwrap)
.collect::<BTreeSet<_>>()
};
let found = list_instances();
let expected: BTreeSet<_> = whiches
.iter()
.filter(|which| which.dir || which.lockfile)
.map(|which| Slug::new(which.to_string()).unwrap())
.collect();
itertools::assert_equal(&found, &expected);
// 3. Run a purge and check that we see the expected callbacks
struct PurgeHandler<'r> {
expected: &'r BTreeSet<Slug>,
}
impl Which {
fn old_enough_to_vanish(&self) -> bool {
self.age > self.max_age
}
}
impl InstancePurgeHandler for PurgeHandler<'_> {
fn kind(&self) -> &'static str {
"which"
}
fn name_filter(&mut self, id: &SlugRef) -> Result<Liveness> {
eprintln!("{id} - name_filter");
assert!(self.expected.contains(id));
let which: Which = id.as_str().parse().unwrap();
Ok(if which.namefilter_live {
Liveness::Live
} else {
Liveness::PossiblyUnused
})
}
fn age_filter(&mut self, id: &SlugRef, age: Duration) -> Result<Liveness> {
eprintln!("{id} - age_filter({age:?})");
let which: Which = id.as_str().parse().unwrap();
assert!(!which.namefilter_live);
Ok(if age <= days(which.max_age) {
Liveness::Live
} else {
Liveness::PossiblyUnused
})
}
fn dispose(
&mut self,
info: &InstancePurgeInfo,
handle: InstanceStateHandle,
) -> Result<()> {
let id = info.identity();
eprintln!("{id} - dispose");
let which: Which = id.as_str().parse().unwrap();
assert!(!which.namefilter_live);
assert!(which.old_enough_to_vanish());
assert!(which.dir);
handle.purge()
}
}
state_dir
.purge_instances(
now(),
&mut PurgeHandler {
expected: &expected,
},
)
.unwrap();
// 4. List the instances again and check the results
let found = list_instances();
let expected: BTreeSet<_> = whiches
.iter()
.filter(|which| {
if which.namefilter_live {
// things filtered by the name filter are left alone;
// we see them if any bits of them existed, even a stale lockfile
which.dir || which.lockfile
} else {
// things *not* filtered by the name filter are retained
// iff the directory exists and is new enough
which.dir && !which.old_enough_to_vanish()
}
})
.map(|which| Slug::new(which.to_string()).unwrap())
.collect();
itertools::assert_equal(&found, &expected);
// 5. Check that the junk was ignored
for (p, is_dir) in junk {
let md = fs::metadata(&p).unwrap();
assert_eq!(md.is_dir(), is_dir, "{}", p.display_lossy());
}
}
#[test]
#[traced_test]
fn test_reset_expiry() {
// Tests that things that should update the instance mtime do so,
// and that things that shouldhn't, don't.
//
// For each test case, we:
// 1. create a new subdirectory of our temp dir, making a new StateDirectory.
// 2. (optionally) set up one instance within it, containing one pre-prepared
// existing storage file and one pre-prepared (empty) raw subdir
// 3. perform test-case specific actions on the instance
// 4. run a stunt `purge_instances` call that merely checks
// that the right value was passed to age_filter
let temp_dir = test_temp_dir!();
const KIND: &str = "kind";
// keys for various sub-objects
const S_EXISTS: &str = "state-existing";
const S_ABSENT: &str = "state-initially-absent";
const R_EXISTS: &str = "raw-subdir-existing";
const R_ABSENT: &str = "raw-subdir-initially-absent";
struct FixedId;
impl InstanceIdentity for FixedId {
fn kind() -> &'static str {
KIND
}
fn write_identity(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "id")
}
}
/// Did we expect this test case's actions to change the mtime?
#[derive(PartialEq, Debug)]
enum Expect {
/// mtime should be updated
New,
/// mtime should be unchanged
Old,
}
use Expect as Ex;
/// Callbacks for stunt purge
///
/// `self == None` means we've called `age_filter` already.
#[allow(non_local_definitions)] // rust-lang/rust#125068
impl InstancePurgeHandler for Option<&'_ Expect> {
fn kind(&self) -> &'static str {
KIND
}
fn name_filter(&mut self, _identity: &SlugRef) -> Result<Liveness> {
Ok(Liveness::PossiblyUnused)
}
fn age_filter(&mut self, _identity: &SlugRef, age: Duration) -> Result<Liveness> {
let did_reset = if age < days(1) { Ex::New } else { Ex::Old };
assert_eq!(&did_reset, self.unwrap());
*self = None;
// Stop processing the instance
Ok(Liveness::Live)
}
fn dispose(
&mut self,
_info: &InstancePurgeInfo<'_>,
_handle: InstanceStateHandle,
) -> Result<()> {
panic!("disposed live")
}
}
/// Helper for test that purge iteration doesn't itself update the mtime
///
/// Says `PossiblyUnused` so that `dispose` gets called,
/// but then just drops the handle and doesn't delete.
struct ExamineAll;
impl InstancePurgeHandler for ExamineAll {
fn kind(&self) -> &'static str {
KIND
}
fn name_filter(&mut self, _identity: &SlugRef) -> Result<Liveness> {
Ok(Liveness::PossiblyUnused)
}
fn age_filter(&mut self, _identity: &SlugRef, _age: Duration) -> Result<Liveness> {
Ok(Liveness::PossiblyUnused)
}
fn dispose(
&mut self,
_info: &InstancePurgeInfo<'_>,
_handle: InstanceStateHandle,
) -> Result<()> {
Ok(())
}
}
// Run a check (raw - doesn't creating an initial instance state)
let chk_without_create = |exp: Expect, which: &str, acts: &dyn Fn(&StateDirectory)| {
temp_dir.subdir_used_by(which, |dir| {
let state_dir = mk_state_dir(&dir);
acts(&state_dir);
let mut exp = Some(&exp);
state_dir.purge_instances(now(), &mut exp).unwrap();
assert!(exp.is_none(), "age_filter not called, instance missing?");
});
};
// Run a check with a prepared instance state
//
// The preprepared instance:
// - has an existing storage at key S_EXISTS
// - has an existing empty raw subdir at key R_EXISTS
// - has been acquired, so `acts` gets an handle
// - but all of this (looks like it) happened 2 days ago
let chk =
|exp: Expect, which: &str, acts: &dyn Fn(&StateDirectory, InstanceStateHandle)| {
chk_without_create(exp, which, &|state_dir| {
let inst = state_dir.acquire_instance(&FixedId).unwrap();
inst.storage_handle(S_EXISTS)
.unwrap()
.store(&StoredData { some_value: 1 })
.unwrap();
inst.raw_subdir(R_EXISTS).unwrap();
let mtime = now() - days(2);
filetime::set_file_mtime(inst.dir.as_path(), mtime.into()).unwrap();
acts(state_dir, inst);
});
};
// Test things that shouldn't count for keeping an instance alive
chk(Ex::Old, "just-releasing-acquired", &|_, inst| {
drop(inst);
});
chk(Ex::Old, "loading", &|_, inst| {
let load = |key| {
inst.storage_handle::<StoredData>(key)
.unwrap()
.load()
.unwrap()
};
assert!(load(S_EXISTS).is_some());
assert!(load(S_ABSENT).is_none());
});
chk(Ex::Old, "messing-in-subdir", &|_, inst| {
// we don't have a raw subdir path here, but we know what it is
let in_raw = inst.dir.as_path().join(R_EXISTS).join("new");
let _: File = File::create(in_raw).unwrap();
});
chk(Ex::Old, "purge-iter-no-delete", &|state_dir, inst| {
drop(inst);
// ExamineAll looks at everything but never calls InstanceStateHandle::purge.
// It it causes every instance to be locked, but not mtime-updated.
state_dir.purge_instances(now(), &mut ExamineAll).unwrap();
});
// Test things that *should* count for keeping an instance alive
chk_without_create(Ex::New, "acquire-new-instance", &|state_dir| {
state_dir.acquire_instance(&FixedId).unwrap();
});
chk(Ex::New, "acquire-existing-instance", &|state_dir, inst| {
drop(inst);
state_dir.acquire_instance(&FixedId).unwrap();
});
for storage_key in [S_EXISTS, S_ABSENT] {
chk(Ex::New, &format!("store-{}", storage_key), &|_, inst| {
inst.storage_handle(storage_key)
.unwrap()
.store(&StoredData { some_value: 2 })
.unwrap();
});
}
for raw_dir in [R_EXISTS, R_ABSENT] {
chk(Ex::New, &format!("raw_subdir-{}", raw_dir), &|_, inst| {
let _: InstanceRawSubdir = inst.raw_subdir(raw_dir).unwrap();
});
}
}
}