1use std::collections::HashMap;2use std::ffi::{OsStr, OsString};3use std::fmt::{self, Display};4use std::path::PathBuf;5use std::process::Stdio;6use std::sync::{Arc, OnceLock};78use anyhow::{anyhow, bail, ensure, Context, Result};9use futures::StreamExt;10use itertools::Itertools;11use r2d2::{Pool, PooledConnection};12use serde::de::DeserializeOwned;13use serde::{Deserialize, Serialize};14use tokio::io::AsyncWriteExt;15use tokio::process::{ChildStderr, ChildStdin, ChildStdout, Command};16use tokio::select;17use tokio::sync::{mpsc, oneshot};18use tokio_util::codec::{FramedRead, LinesCodec};19use tracing::{debug, error, warn};2021use crate::command::{ClonableHandler, Handler, NixHandler, NoopHandler};2223const REPL_DELIMITER: &str = "\"FLEET_MAGIC_REPL_DELIMITER\"";2425pub struct NixSessionInner {26 full_delimiter: String,27 nix_handler: ClonableHandler<NixHandler>,28 out: OutputHandler,29 stdin: ChildStdin,30 string_wrapping: (String, String),31 number_wrapping: (String, String),3233 next_id: u32,34 free_list: Vec<u32>,35}36const TRAIN_STRING: &str = "\"TRAIN_STRING\"";37const TRAIN_NUMBER: &str = "13141516";3839#[must_use]40struct ErrorCollector<'i, H> {41 collected: Vec<String>,42 inner: &'i mut H,43}44impl<'i, H> ErrorCollector<'i, H> {45 fn new(inner: &'i mut H) -> Self {46 Self {47 collected: vec![],48 inner,49 }50 }51}52impl<H> ErrorCollector<'_, H> {53 fn handle_line_inner(&mut self, msg: &str) -> bool {54 let Some(msg) = msg.strip_prefix("@nix ") else {55 return false;56 };57 #[derive(Deserialize)]58 struct ErrorAction {59 action: String,60 level: u32,61 msg: String,62 }63 let Ok(act) = serde_json::from_str::<ErrorAction>(msg) else {64 return false;65 };66 if act.action != "msg" || act.level != 0 {67 return false;68 }69 self.collected.push(act.msg);70 true71 }72 fn finish(self) -> Result<()> {73 74 75 76 if !self.collected.is_empty() {77 bail!(78 "{}",79 self.collected80 .iter()81 .map(|v| {82 if let Some(f) = v.strip_prefix("\u{1b}[31;1merror:\u{1b}[0m ") {83 let v = unindent::unindent(f.trim_start());84 v.trim().to_owned()85 } else {86 v.to_owned()87 }88 })89 .join("\n")90 );91 }92 Ok(())93 }94 fn flush(self) {95 for line in self.collected {96 warn!("{line}");97 }98 }99}100impl<H: Handler> Handler for ErrorCollector<'_, H> {101 fn handle_line(&mut self, e: &str) {102 if self.handle_line_inner(e) {103 return;104 }105 self.inner.handle_line(e)106 }107}108109enum OutputLine {110 Out(String),111 Err(String),112}113struct OutputHandler {114 rx: mpsc::Receiver<OutputLine>,115 _cancel_handle: oneshot::Receiver<()>,116}117impl OutputHandler {118 fn new(out: ChildStdout, err: ChildStderr) -> Self {119 let mut out = FramedRead::new(out, LinesCodec::new());120 let mut err = FramedRead::new(err, LinesCodec::new());121 let (tx, rx) = mpsc::channel(20);122 let (mut cancelled, _cancel_handle) = oneshot::channel();123 tokio::spawn(async move {124 loop {125 select! {126 127 biased;128 e = err.next() => {129 let Some(Ok(e)) = e else {130 if e.is_some() {131 error!("bad repl stderr: {e:?}");132 }133 continue;134 };135 let _ = tx.send(OutputLine::Err(e)).await;136 }137 o = out.next() => {138 let Some(Ok(o)) = o else {139 if o.is_some() {140 error!("bad repl stdout: {o:?}");141 }142 continue;143 };144 let _ = tx.send(OutputLine::Out(o)).await;145 }146 147 148 _ = cancelled.closed() => {149 break;150 }151 }152 }153 });154 Self { rx, _cancel_handle }155 }156 async fn next(&mut self) -> Option<OutputLine> {157 self.rx.recv().await158 }159}160161struct WarnHandler;162impl Handler for WarnHandler {163 fn handle_line(&mut self, e: &str) {164 warn!(target: "nix", "{e}")165 }166}167168impl NixSessionInner {169 async fn new(flake: &OsStr, extra_args: impl IntoIterator<Item = &OsStr>) -> Result<Self> {170 let mut cmd = Command::new("nix");171 cmd.arg("repl")172 .arg(flake)173 .arg("--log-format")174 .arg("internal-json");175 for arg in extra_args {176 cmd.arg(arg);177 }178 cmd.stdin(Stdio::piped());179 cmd.stdout(Stdio::piped());180 cmd.stderr(Stdio::piped());181 let cmd = cmd.spawn()?;182 let stdout = cmd.stdout.unwrap();183 let stderr = cmd.stderr.unwrap();184 let mut out = OutputHandler::new(stdout, stderr);185 let mut stdin = cmd.stdin.unwrap();186 187 stdin.write_all(REPL_DELIMITER.as_bytes()).await?;188 stdin.write_all(b"\n").await?;189 stdin.flush().await?;190 let nix_handler = NixHandler::default();191 let mut full_delimiter = None;192 let mut errors = vec![];193 while let Some(line) = out.next().await {194 let line = match line {195 OutputLine::Out(o) => o,196 OutputLine::Err(_e) => {197 198 errors.push(_e);199 continue;200 }201 };202 if line.contains(REPL_DELIMITER) {203 debug!("discovered repl delimiter with added colors: {line}");204 full_delimiter = Some(line.to_owned());205 break;206 }207 }208 let Some(full_delimiter) = full_delimiter else {209 for e in errors {210 error!("{e}");211 }212 bail!("failed to discover delimiter");213 };214 let mut res = Self {215 full_delimiter,216 nix_handler: ClonableHandler::new(nix_handler),217 out,218 stdin,219 string_wrapping: Default::default(),220 number_wrapping: Default::default(),221222 next_id: 0,223 free_list: vec![],224 };225 res.train().await?;226 Ok(res)227 }228 async fn train(&mut self) -> Result<()> {229 {230 let full_string = self231 .execute_expression_raw(TRAIN_STRING, &mut NoopHandler)232 .await?;233 let string_offset = full_string.find(TRAIN_STRING).expect("contained");234 let string_prefix = &full_string[..string_offset];235 let string_suffix = &full_string[string_offset + TRAIN_STRING.len()..];236 self.string_wrapping = (string_prefix.to_owned(), string_suffix.to_owned());237 }238 {239 let full_number = self240 .execute_expression_raw(TRAIN_NUMBER, &mut NoopHandler)241 .await?;242 let number_offset = full_number.find(TRAIN_NUMBER).expect("contained");243 let number_prefix = &full_number[..number_offset];244 let number_suffix = &full_number[number_offset + TRAIN_NUMBER.len()..];245 self.number_wrapping = (number_prefix.to_owned(), number_suffix.to_owned());246 }247 Ok(())248 }249 async fn send_command(&mut self, cmd: impl AsRef<[u8]>) -> Result<()> {250 self.stdin.write_all(cmd.as_ref()).await?;251 self.stdin.write_all(b"\n").await?;252 Ok(())253 }254 async fn read_until_delimiter(&mut self, err_handler: &mut dyn Handler) -> Result<String> {255 let mut out = String::new();256 while let Some(line) = self.out.next().await {257 let line = match line {258 OutputLine::Out(out) => out,259 OutputLine::Err(err) => {260 err_handler.handle_line(&err);261 continue;262 }263 };264 if line == self.full_delimiter {265 return Ok(out);266 }267 if !out.is_empty() {268 out.push('\n');269 }270 out.push_str(&line);271 }272 bail!("didn't reached delimiter");273 }274 async fn execute_expression_number(&mut self, expr: impl AsRef<[u8]>) -> Result<u64> {275 let num = self.number_wrapping.clone();276 let n = self.execute_expression_wrapping(expr, &num).await?;277 Ok(n.parse::<u64>()?)278 }279 async fn execute_expression_string(&mut self, expr: impl AsRef<[u8]>) -> Result<String> {280 let num = self.string_wrapping.clone();281 let n = self.execute_expression_wrapping(expr, &num).await?;282 let str: String = serde_json::from_str(&n)?;283 Ok(str)284 }285 async fn execute_expression_to_json<V: DeserializeOwned>(286 &mut self,287 expr: impl AsRef<[u8]>,288 ) -> Result<V> {289 let mut fexpr = b"builtins.toJSON (".to_vec();290 fexpr.extend_from_slice(expr.as_ref());291 fexpr.push(b')');292 let v = self.execute_expression_string(fexpr).await?;293 Ok(serde_json::from_str(&v)?)294 }295 async fn execute_expression_wrapping(296 &mut self,297 expr: impl AsRef<[u8]>,298 wrapping: &(String, String),299 ) -> Result<String> {300 let mut nix_handler = self.nix_handler.clone();301 let mut collected = ErrorCollector::new(&mut nix_handler);302 let res = self.execute_expression_raw(expr, &mut collected).await?;303 if res.is_empty() {304 collected.finish()?;305 bail!("expected expression, got nothing")306 } else {307 collected.flush()308 };309 let Some(res) = res.strip_prefix(&wrapping.0) else {310 bail!("invalid type")311 };312 let Some(res) = res.strip_suffix(&wrapping.1) else {313 bail!("invalid type")314 };315 Ok(res.to_owned())316 }317 async fn execute_expression_empty(&mut self, expr: impl AsRef<[u8]>) -> Result<()> {318 let mut nix_handler = self.nix_handler.clone();319 let mut collected = ErrorCollector::new(&mut nix_handler);320 let v = self.execute_expression_raw(expr, &mut collected).await?;321 collected.finish()?;322 ensure!(v.is_empty(), "unexpected expression result");323 Ok(())324 }325 async fn execute_expression_raw(326 &mut self,327 expr: impl AsRef<[u8]>,328 err_handler: &mut dyn Handler,329 ) -> Result<String> {330 self.send_command(expr).await?;331 332 self.send_command(REPL_DELIMITER).await?;333 self.read_until_delimiter(err_handler).await334 }335 async fn execute_assign(&mut self, expr: impl AsRef<str>) -> Result<u32> {336 let id = self.allocate_id();337 self.execute_expression_empty(format!("sess_field_{id} = {}", expr.as_ref()))338 .await?;339 Ok(id)340 }341342 343 fn allocate_id(&mut self) -> u32 {344 if let Some(free) = self.free_list.pop() {345 free346 } else {347 let v = self.next_id;348 self.next_id += 1;349 v350 }351 }352 353 354 355 356 357 358 359}360361#[derive(Clone)]362pub struct NixSession(Arc<tokio::sync::Mutex<PooledConnection<NixSessionPoolInner>>>);363364#[macro_export]365macro_rules! nix_path {366 (@o($o:ident) $var:ident $($tt:tt)*) => {{367 $o.push(Index::var(stringify!($var)));368 nix_path!(@o($o) $($tt)*);369 }};370 (@o($o:ident) . $var:ident $($tt:tt)*) => {{371 $o.push(Index::attr(stringify!($var)));372 nix_path!(@o($o) $($tt)*);373 }};374 (@o($o:ident) . $var:literal $($tt:tt)*) => {{375 $o.push(Index::attr($var));376 nix_path!(@o($o) $($tt)*);377 }};378 (@o($o:ident) . { $var:expr } $($tt:tt)*) => {{379 $o.push(Index::attr($var));380 nix_path!(@o($o) $($tt)*);381 }};382 (@o($o:ident) [ $var:literal ] $($tt:tt)*) => {{383 $o.push(Index::idx($var));384 nix_path!(@o($o) $($tt)*);385 }};386 (@o($o:ident) ($e:expr) $($tt:tt)*) => {387 $o.push(Index::apply($e));388 nix_path!(@o($o) $($tt)*);389 };390 (@o($o:ident)) => {};391 ($($tt:tt)+) => {{392 use $crate::{nix_path, better_nix_eval::Index};393 let mut out = vec![];394 nix_path!(@o(out) $($tt)*);395 out396 }}397}398399#[derive(Clone)]400pub enum Index {401 Var(String),402 String(String),403 Apply(String),404 Idx(u32),405}406impl Index {407 pub fn var(v: impl AsRef<str>) -> Self {408 let v = v.as_ref();409 assert!(410 !(v.contains('.') | v.contains(' ')),411 "bad variable name: {v}"412 );413 Self::Var(v.to_owned())414 }415 pub fn attr(v: impl AsRef<str>) -> Self {416 Self::String(v.as_ref().to_owned())417 }418 pub fn idx(v: u32) -> Self {419 Self::Idx(v)420 }421 pub fn apply(v: impl Serialize) -> Self {422 let serialized = nixlike::serialize(v).expect("invalid value for apply");423 Self::Apply(serialized)424 }425}426impl Display for Index {427 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {428 match self {429 Index::Var(v) => {430 write!(f, "{v}")431 }432 Index::String(k) => {433 let v = nixlike::format_identifier(k.as_str());434 write!(f, ".{v}")435 }436 Index::Apply(o) => {437 let v = nixlike::serialize(o).map_err(|_| fmt::Error)?;438 write!(f, "<apply>({v})")439 }440 Index::Idx(i) => {441 write!(f, "[{i}]")442 }443 }444 }445}446impl fmt::Debug for Index {447 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {448 write!(f, "{self}")449 }450}451struct PathDisplay<'i>(&'i [Index]);452impl Display for PathDisplay<'_> {453 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {454 write!(f, "flake")?;455 for i in self.0 {456 write!(f, "{i}")?;457 }458 Ok(())459 }460}461pub struct Field {462 full_path: Vec<Index>,463 session: NixSession,464 value: Option<u32>,465}466impl Field {467 fn root(session: NixSession) -> Self {468 Self {469 full_path: vec![],470 session,471 value: None,472 }473 }474 pub async fn field(session: NixSession, field: &str) -> Result<Self> {475 Self::root(session)476 .select([Index::var(field)])477 .await478 }479 pub async fn get_json_deep<'a, V: DeserializeOwned>(480 &self,481 name: impl IntoIterator<Item = Index>,482 ) -> Result<V> {483 let field = self.select(name).await?;484 field.as_json().await485 }486 pub async fn select<'a>(&self, name: impl IntoIterator<Item = Index>) -> Result<Self> {487 let mut name = name.into_iter();488489 let mut full_path = self.full_path.clone();490 let mut query = if let Some(id) = self.value {491 format!("sess_field_{id}")492 } else {493 let first = name.next();494 if let Some(Index::Var(i)) = first {495 full_path.push(Index::Var(i.clone()));496 i.clone()497 } else {498 panic!("first path item should be variable, got {first:?}")499 }500 };501 for v in name {502 full_path.push(v.clone());503 match v {504 Index::Var(_) => panic!("var item may only be first"),505 Index::String(s) => {506 let escaped = nixlike::serialize(s)?;507 query.push('.');508 query.push_str(escaped.trim());509 }510 Index::Apply(a) => {511 query.push(' ');512 query.push_str(&a);513 }514 Index::Idx(idx) => {515 query = format!("builtins.elemAt ({query}) {idx}");516 }517 }518 }519520 let vid = self521 .session522 .0523 .lock()524 .await525 .execute_assign(&query)526 .await527 .with_context(|| format!("full path: {}", PathDisplay(&full_path)))?;528 Ok(Self {529 full_path,530 session: self.session.clone(),531 value: Some(vid),532 })533 }534 pub async fn as_json<V: DeserializeOwned>(&self) -> Result<V> {535 let id = self.value.expect("can't serialize root field");536 self.session537 .0538 .lock()539 .await540 .execute_expression_to_json(&format!("sess_field_{id}"))541 .await542 .with_context(|| format!("full path: {}", PathDisplay(&self.full_path)))543 }544 pub async fn list_fields(&self) -> Result<Vec<String>> {545 let id = self.value.expect("can't list root fields");546 self.session547 .0548 .lock()549 .await550 .execute_expression_to_json(&format!("builtins.attrNames sess_field_{id}"))551 .await552 .with_context(|| format!("full path: {}", PathDisplay(&self.full_path)))553 }554 pub async fn build(&self) -> Result<HashMap<String, PathBuf>> {555 let id = self.value.expect("can't use build on not-value");556 let vid = self557 .session558 .0559 .lock()560 .await561 .execute_expression_raw(&format!(":b sess_field_{id}"), &mut NixHandler::default())562 .await?;563 ensure!(!vid.is_empty(), "build failed");564 let Some(vid) = vid.strip_prefix("This derivation produced the following outputs:\n")565 else {566 panic!("unexpected build output: {vid:?}");567 };568 let outputs = vid569 .split('\n')570 .filter(|v| !v.is_empty())571 .map(|v| v.split_once(" -> ").expect("unexpected build output"))572 .map(|(a, b)| (a.trim_start().to_owned(), PathBuf::from(b)))573 .collect();574 Ok(outputs)575 }576}577impl Drop for Field {578 fn drop(&mut self) {579 if let Some(id) = self.value {580 if let Ok(mut lock) = self.session.0.try_lock() {581 lock.free_list.push(id)582 }583 584 }585 }586}587struct NixSessionPoolInner {588 flake: OsString,589 nix_args: Vec<OsString>,590}591592#[derive(Debug)]593pub struct NixPoolError(anyhow::Error);594impl From<anyhow::Error> for NixPoolError {595 fn from(value: anyhow::Error) -> Self {596 Self(value)597 }598}599impl std::error::Error for NixPoolError {}600impl std::fmt::Display for NixPoolError {601 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {602 self.0.fmt(f)603 }604}605impl r2d2::ManageConnection for NixSessionPoolInner {606 type Connection = NixSessionInner;607 type Error = NixPoolError;608 fn connect(&self) -> std::result::Result<Self::Connection, Self::Error> {609 let _v = TOKIO_RUNTIME610 .get()611 .expect("missed tokio runtime init!")612 .enter();613 Ok(futures::executor::block_on(NixSessionInner::new(614 self.flake.as_os_str(),615 self.nix_args.iter().map(OsString::as_os_str),616 ))?)617 }618619 fn is_valid(&self, conn: &mut Self::Connection) -> std::result::Result<(), Self::Error> {620 let _v = TOKIO_RUNTIME621 .get()622 .expect("missed tokio runtime init!")623 .enter();624 let res = futures::executor::block_on(conn.execute_expression_number("2 + 2"))?;625 if res != 4 {626 return Err(anyhow!("sanity check failed").into());627 };628 Ok(())629 }630631 fn has_broken(&self, _conn: &mut Self::Connection) -> bool {632 false633 }634}635pub struct NixSessionPool(Pool<NixSessionPoolInner>);636impl NixSessionPool {637 pub async fn new(flake: OsString, nix_args: Vec<OsString>) -> Result<Self> {638 let inner = tokio::task::block_in_place(|| {639 r2d2::Builder::<NixSessionPoolInner>::new()640 .min_idle(Some(0))641 .build(NixSessionPoolInner { flake, nix_args })642 })?;643 Ok(Self(inner))644 }645 pub async fn get(&self) -> Result<NixSession> {646 let v = tokio::task::block_in_place(|| self.0.get())?;647 Ok(NixSession(Arc::new(tokio::sync::Mutex::new(v))))648 }649}650651pub static TOKIO_RUNTIME: OnceLock<tokio::runtime::Handle> = OnceLock::new();