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use std::{
collections::BTreeSet,
convert::AsRef,
path::{Path, PathBuf},
time::Duration,
};
use bincode::{Decode, Encode};
use futures::future::try_join_all;
use itertools::Itertools;
use regex::Regex;
use snafu::{OptionExt, ResultExt, Snafu};
use surf::{Response, StatusCode};
use tracing::{debug, debug_span, error, info, instrument, trace, Instrument};
use super::NixConfiguration;
/// Error interacting with the `Nix` store
#[derive(Debug, Snafu)]
#[non_exhaustive]
pub enum StoreError {
/// Failure initially enumerating the nix store
InitialEnumeration {
/// Underlying IO error
source: std::io::Error,
/// The configuration in use
configuration: NixConfiguration,
},
/// Mid-enumeration failure
Enumeration {
/// Underlying IO error
source: std::io::Error,
/// The configuration in use
configuration: NixConfiguration,
},
/// Error stripping prefix, this is indicative of a configuration error
StripPrefix {
/// Underlying error
source: std::path::StripPrefixError,
},
/// Error building a regex, this really shouldn't happen
Regex {
/// Underlying error
source: regex::Error,
},
/// Error parsing a nix store path
PathParsing,
/// Error checking the cache
CacheError {
/// Underlying error
e: surf::Error,
},
/// Tried to compare stores with different prefixes
DifferentPrefixes,
/// Unknown response
#[snafu(display("Unknown response from cache: {:?}",response.status()))]
UnknownReponse {
/// Failed response
response: Box<Response>,
},
}
/// The state of the `Nix` store at a given point in time
#[derive(Clone, Debug, PartialEq, Eq, Default, Encode, Decode)]
pub struct StoreState {
/// Currently in use nix configuration
config: NixConfiguration,
/// The set of all paths top level paths in the store at the time the snapshot was taken
store_state: BTreeSet<PathBuf>,
}
impl StoreState {
/// Create a new, empty, `StoreState` with the specified `Nix` configuration
pub fn new(config: NixConfiguration) -> Self {
Self {
config,
store_state: BTreeSet::new(),
}
}
/// Add a path to the `StoreState`
///
/// # Errors
///
/// Will propagate an error if the prefix is impossible to strip due to misconfiguration
pub fn add_path(&mut self, path: impl AsRef<Path>) -> Result<(), StoreError> {
self.store_state.insert(
path.as_ref()
.strip_prefix(&self.config.store_path)
.context(StripPrefixSnafu)?
.to_owned(),
);
Ok(())
}
/// Iterator over the paths in this `StoreState`
pub fn paths(&self) -> impl Iterator<Item = PathBuf> + '_ {
self.store_state
.iter()
.map(|x| self.config.store_path.join(x))
}
/// Return all paths that are different between this `StoreState` and another `StoreState`
///
/// This returns elements that are in `other`, but not in `self`
///
/// # Errors
///
/// Will return an error if two stores with incompatible configuration are compared.
pub fn diff(&self, other: &StoreState) -> Result<Self, StoreError> {
// Make sure the store paths are the same, and bail otherwise
if self.config.store_path != other.config.store_path {
return DifferentPrefixesSnafu.fail();
}
let filtered_state: BTreeSet<_> = other
.store_state
.difference(&self.store_state)
.cloned()
.collect();
Ok(Self {
config: other.config.clone(),
store_state: filtered_state,
})
}
/// Returns the number of unique paths in the store
pub fn path_count(&self) -> usize {
self.store_state.len()
}
/// Create a `StoreState` from the current status of the `Nix` store pointed to by the given
/// [`NixConfiguration`] including installables as well as other paths matching the supplied
/// regexes
///
/// # Errors
///
/// Will propagate any IO errors that occur trying to enumerate the `Nix` store
#[instrument(err)]
pub fn from_store_excluding(
configuration: &NixConfiguration,
excludes: &[Regex],
) -> Result<Self, StoreError> {
info!("Generating store state");
// Create a new self to dump paths into
let mut result = Self::new(configuration.clone());
// Attempt to read the directory
let read_dir = std::fs::read_dir(&configuration.store_path).with_context(|_| {
InitialEnumerationSnafu {
configuration: configuration.clone(),
}
})?;
for entry in read_dir.map(|x| {
x.with_context(|_| EnumerationSnafu {
configuration: configuration.clone(),
})
}) {
// Pass up the error if there is one
let entry = entry?;
trace!(?entry);
// Make sure it's an either an installable (directory) or matches an include filter
// first, and then add it to ourself
if let Ok(metadata) = entry.metadata() {
// I _think_ we are safe to make the assumption that any directory is an installable
// TODO: Interact with nix to get a more "correct" solution here.
let installable = metadata.is_dir();
// We use a lossy to utf-8 conversion here to make the regexes more ergonomic to
// deal with, I don't think this will be an issue as we are only concerned with
// fairly well behaved top level nix store paths
let included = !excludes
.iter()
.any(|x| x.is_match(&entry.path().to_string_lossy()));
if entry.path().exists() && installable && included {
result.add_path(entry.path())?;
}
}
}
// Return
Ok(result)
}
/// Create a `StoreState` from the current status of the `Nix` store pointed to by the given
/// [`NixConfiguration`]
///
/// This is a wrapper around [`from_store_excluding`](Self::from_store_excluding) with the
/// default include filters implied.
///
/// The default filters will include:
/// - Any installable (non-disableable)
/// - Any `nix-shell` derivations
///
/// # Errors
///
/// Will propagate any IO errors that occur trying to enumerate the `Nix` store
#[instrument(err)]
pub fn from_store(configuration: &NixConfiguration) -> Result<Self, StoreError> {
// Filter out naresk `unpack` derviations
// let unpack_regex = Regex::new(r"/nix/store/[a-z0-9]*-unpack-").context(RegexSnafu)?;
Self::from_store_excluding(configuration, &[])
}
/// Filter this `Store` state against the given nix binary cache, removing any paths that are
/// present in the cache. The provided cache uri is expected not to have a trailing slash
///
/// # Errors
///
/// Will propagate any network or nix store interaction errors that occur
#[instrument(skip(self))]
pub async fn filter_against_cache(self, cache_uri: &str) -> Result<Self, StoreError> {
let max_connections = 100;
let client: surf::Client = surf::Config::new()
.set_timeout(Some(Duration::from_millis(1000)))
.set_max_connections_per_host(max_connections)
.try_into()
.unwrap();
let cache_uri: String = cache_uri.to_owned();
let mut filtered_state: BTreeSet<PathBuf> = BTreeSet::new();
// Chunk the state by the number of allowed connections
for chunk in &self.store_state.into_iter().chunks(max_connections * 4) {
// Await all the chunks at the same time
let filtered_chunk = try_join_all(chunk.map(|store_path| {
let client = client.clone();
let cache_uri = cache_uri.clone();
async move {
trace!(?store_path, "Checking path against cache");
// Construct the combined uri, first peel off the hash
//
// The hash should always be the first element, as the store internally
// strips its paths of the store prefix
let hash = store_path
.to_string_lossy()
.split('-')
.next()
.context(PathParsingSnafu)?
.to_owned();
// Now build the expected narinfo uri
let narinfo_uri = format!("{cache_uri}/{hash}.narinfo");
trace!(?narinfo_uri, "Checking for narinfo on remote");
// Now check the cache for it
let result = client.send(surf::head(&narinfo_uri)).await;
// Processing this error is actually kind of involved, we want to
// include it if we get a response code of 404, include it if we get a
// 200 OK, and error if we encounter any other response code
match result {
// If this was okay, check to see if the narinfo is in the cache so we can
// filter it out
Ok(response) => {
match response.status() {
StatusCode::Ok => {
// We were in the cache, filter her out
debug!(
?store_path,
?narinfo_uri,
"Store path in cache, filtering"
);
Ok(None)
}
StatusCode::NotFound => {
// We were not in the cache, keep it
Ok(Some(store_path.clone()))
}
_ => {
error!(?response, "Unknown response type");
UnknownReponseSnafu { response }.fail()
}
}
}
// If there was an error, check to see if it was a 404
Err(e) => {
if e.status() == surf::StatusCode::NotFound {
// In this case, we can include the path
trace!(?store_path, "Store path not in cache");
Ok(Some(store_path.clone()))
} else {
// In this case we need to bubble up the error
let status = e.status();
error!(?e, ?status, ?narinfo_uri, "Error interacting with cache");
CacheSnafu { e }.fail()
}
}
}
}
.instrument(debug_span!("Narinfo presence checking task"))
}))
.await?;
filtered_state.extend(filtered_chunk.into_iter().flatten());
}
Ok(Self {
config: self.config,
store_state: filtered_state,
})
}
}