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, Level};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 if tracing::enabled!(Level::DEBUG) {251 let cmd_str = String::from_utf8_lossy(cmd.as_ref());252 tracing::debug!("{cmd_str}");253 };254 self.stdin.write_all(cmd.as_ref()).await?;255 self.stdin.write_all(b"\n").await?;256 Ok(())257 }258 async fn read_until_delimiter(&mut self, err_handler: &mut dyn Handler) -> Result<String> {259 let mut out = String::new();260 while let Some(line) = self.out.next().await {261 let line = match line {262 OutputLine::Out(out) => out,263 OutputLine::Err(err) => {264 err_handler.handle_line(&err);265 continue;266 }267 };268 if line == self.full_delimiter {269 return Ok(out);270 }271 if !out.is_empty() {272 out.push('\n');273 }274 out.push_str(&line);275 }276 bail!("didn't reached delimiter");277 }278 async fn execute_expression_number(&mut self, expr: impl AsRef<[u8]>) -> Result<u64> {279 let num = self.number_wrapping.clone();280 let n = self.execute_expression_wrapping(expr, &num).await?;281 Ok(n.parse::<u64>()?)282 }283 async fn execute_expression_string(&mut self, expr: impl AsRef<[u8]>) -> Result<String> {284 let num = self.string_wrapping.clone();285 let n = self.execute_expression_wrapping(expr, &num).await?;286 let str: String = serde_json::from_str(&n)?;287 Ok(str)288 }289 async fn execute_expression_to_json<V: DeserializeOwned>(290 &mut self,291 expr: impl AsRef<[u8]>,292 ) -> Result<V> {293 let mut fexpr = b"builtins.toJSON (".to_vec();294 fexpr.extend_from_slice(expr.as_ref());295 fexpr.push(b')');296 let v = self.execute_expression_string(fexpr).await?;297 Ok(serde_json::from_str(&v)?)298 }299 async fn execute_expression_wrapping(300 &mut self,301 expr: impl AsRef<[u8]>,302 wrapping: &(String, String),303 ) -> Result<String> {304 let mut nix_handler = self.nix_handler.clone();305 let mut collected = ErrorCollector::new(&mut nix_handler);306 let res = self.execute_expression_raw(expr, &mut collected).await?;307 if res.is_empty() {308 collected.finish()?;309 bail!("expected expression, got nothing")310 } else {311 collected.flush()312 };313 let Some(res) = res.strip_prefix(&wrapping.0) else {314 bail!("invalid type")315 };316 let Some(res) = res.strip_suffix(&wrapping.1) else {317 bail!("invalid type")318 };319 Ok(res.to_owned())320 }321 async fn execute_expression_empty(&mut self, expr: impl AsRef<[u8]>) -> Result<()> {322 let mut nix_handler = self.nix_handler.clone();323 let mut collected = ErrorCollector::new(&mut nix_handler);324 let v = self.execute_expression_raw(expr, &mut collected).await?;325 collected.finish()?;326 ensure!(v.is_empty(), "unexpected expression result");327 Ok(())328 }329 async fn execute_expression_raw(330 &mut self,331 expr: impl AsRef<[u8]>,332 err_handler: &mut dyn Handler,333 ) -> Result<String> {334 self.send_command(expr).await?;335 336 self.send_command(REPL_DELIMITER).await?;337 self.read_until_delimiter(err_handler).await338 }339 async fn execute_assign(&mut self, expr: impl AsRef<str>) -> Result<u32> {340 let id = self.allocate_id();341 self.execute_expression_empty(format!("sess_field_{id} = {}", expr.as_ref()))342 .await?;343 Ok(id)344 }345346 347 fn allocate_id(&mut self) -> u32 {348 if let Some(free) = self.free_list.pop() {349 free350 } else {351 let v = self.next_id;352 self.next_id += 1;353 v354 }355 }356 357 358 359 360 361 362 363}364365#[derive(Clone)]366pub struct NixSession(Arc<tokio::sync::Mutex<PooledConnection<NixSessionPoolInner>>>);367368#[derive(Clone)]369pub struct NixExprBuilder {370 out: String,371 used_fields: Vec<Field>,372}373impl NixExprBuilder {374 pub fn object() -> Self {375 NixExprBuilder {376 out: "{ ".to_owned(),377 used_fields: Vec::new(),378 }379 }380 pub fn string(s: &str) -> Self {381 NixExprBuilder {382 out: nixlike::serialize(s)383 .expect("no problems with serializing_string")384 .trim_end()385 .to_owned(),386 used_fields: Vec::new(),387 }388 }389 pub fn serialized(v: impl Serialize) -> Self {390 let serialized = nixlike::serialize(v).expect("invalid value for apply");391 Self {392 out: serialized.trim_end().to_owned(),393 used_fields: Vec::new(),394 }395 }396 pub fn field(f: Field) -> Self {397 Self {398 out: format!("sess_field_{}", f.0.value.expect("no value")),399 used_fields: vec![f],400 }401 }402 pub fn end_obj(&mut self) {403 self.out.push('}');404 }405 pub fn obj_key(&mut self, name: Self, value: Self) {406 self.out.push_str(r#""${"#);407 self.extend(name);408 self.out.push_str(r#"}" = "#);409 self.extend(value);410 self.out.push_str("; ");411 }412413 pub fn extend(&mut self, e: Self) {414 self.out.push_str(&e.out);415 self.used_fields.extend(e.used_fields);416 }417418 pub fn session(&self) -> NixSession {419 let mut session = None;420 for ele in &self.used_fields {421 if session.is_none() {422 session = Some(ele.0.session.clone());423 continue;424 }425 let session = &session.as_ref().expect("checked").0;426 let ele_sess = &ele.0.session.0;427 assert!(428 Arc::ptr_eq(session, ele_sess),429 "can't mix fields from different session"430 );431 }432 session.expect("expr without fields used")433 }434 pub fn index_attr(&mut self, s: &str) {435 let escaped = nixlike::serialize(s).expect("string");436 self.out.push('.');437 self.out.push_str(escaped.trim_end());438 }439}440441#[macro_export]442macro_rules! nix_expr_inner {443 (Obj { $($ident:ident: $($val:tt)+),* $(,)? }) => {{444 use $crate::better_nix_eval::NixExprBuilder;445 let mut out = NixExprBuilder::object();446 $(447 out.obj_key(448 NixExprBuilder::string(stringify!($ident)),449 $crate::nix_expr_inner!($($val)+),450 );451 )*452 out.end_obj();453 out454 }};455 (@field($o:ident) . $var:ident $($tt:tt)*) => {{456 $o.index_attr(stringify!($var));457 nix_expr_inner!(@field($o) $($tt)*);458 }};459 (@field($o:ident) [{ $v:expr }] $($tt:tt)*) => {{460 $o.push(Index::attr(&$v));461 nix_expr_inner!(@o($o) $($tt)*);462 }};463 (@field($o:ident) [ $($var:tt)+ ] $($tt:tt)*) => {{464 $o.push(Index::Expr($crate::nix_expr_inner!($($var)+)));465 nix_expr_inner!(@o($o) $($tt)*);466 }};467 (@field($o:ident) ($($var:tt)*) $($tt:tt)*) => {468 $o.push(Index::ExprApply($crate::nix_expr_inner!($($var)+)));469 nix_expr_inner!(@o($o) $($tt)*);470 };471 (@field($o:ident)) => {};472 ($field:ident $($tt:tt)*) => {{473 use $crate::{better_nix_eval::NixExprBuilder, nix_expr_inner};474 #[allow(unused_mut, reason = "might be used if indexed")]475 let mut out = NixExprBuilder::field($field);476 nix_expr_inner!(@field(out) $($tt)*);477 out478 }};479 ($v:literal) => {{480 use $crate::better_nix_eval::NixExprBuilder;481 NixExprBuilder::string($v)482 }};483 ({$v:expr}) => {{484 use $crate::better_nix_eval::NixExprBuilder;485 NixExprBuilder::serialized(&$v)486 }}487}488#[macro_export]489macro_rules! nix_expr {490 ($($tt:tt)+) => {{491 use $crate::{better_nix_eval::{NixExprBuilder, Field}, nix_expr_inner};492 let expr = nix_expr_inner!($($tt)+);493 Field::new(expr.session(), expr.out)494 }};495}496497#[macro_export]498macro_rules! nix_go {499 (@o($o:ident) . $var:ident $($tt:tt)*) => {{500 $o.push(Index::attr(stringify!($var)));501 nix_go!(@o($o) $($tt)*);502 }};503 (@o($o:ident) [{ $v:expr }] $($tt:tt)*) => {{504 $o.push(Index::attr(&$v));505 nix_go!(@o($o) $($tt)*);506 }};507 (@o($o:ident) [ $($var:tt)+ ] $($tt:tt)*) => {{508 $o.push(Index::Expr($crate::nix_expr_inner!($($var)+)));509 nix_go!(@o($o) $($tt)*);510 }};511 (@o($o:ident) ($($var:tt)*) $($tt:tt)*) => {512 $o.push(Index::ExprApply($crate::nix_expr_inner!($($var)+)));513 nix_go!(@o($o) $($tt)*);514 };515 (@o($o:ident)) => {};516 ($field:ident $($tt:tt)+) => {{517 use $crate::{nix_go, better_nix_eval::Index};518 let field = $field.clone();519 let mut out = vec![];520 nix_go!(@o(out) $($tt)*);521 field.select(out).await?522 }}523}524#[macro_export]525macro_rules! nix_go_json {526 ($($tt:tt)*) => {{527 $crate::nix_go!($($tt)*).as_json().await?528 }};529}530531#[derive(Clone)]532pub enum Index {533 Var(String),534 String(String),535 Apply(String),536 Expr(NixExprBuilder),537 ExprApply(NixExprBuilder),538}539impl Index {540 pub fn var(v: impl AsRef<str>) -> Self {541 let v = v.as_ref();542 assert!(543 !(v.contains('.') | v.contains(' ')),544 "bad variable name: {v}"545 );546 Self::Var(v.to_owned())547 }548 pub fn attr(v: impl AsRef<str>) -> Self {549 Self::String(v.as_ref().to_owned())550 }551 pub fn apply(v: impl Serialize) -> Self {552 let serialized = nixlike::serialize(v).expect("invalid value for apply");553 Self::Apply(serialized.trim_end().to_owned())554 }555}556impl Display for Index {557 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {558 match self {559 Index::Var(v) => {560 write!(f, "{v}")561 }562 Index::String(k) => {563 let v = nixlike::format_identifier(k.as_str());564 write!(f, ".{v}")565 }566 Index::Apply(o) => {567 write!(f, "<apply>({o})")568 }569 Index::Expr(e) => {570 write!(f, "[{}]", e.out)571 }572 Index::ExprApply(e) => {573 write!(f, "<apply>({})", e.out)574 }575 }576 }577}578impl fmt::Debug for Index {579 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {580 write!(f, "{self}")581 }582}583struct PathDisplay<'i>(&'i [Index]);584impl Display for PathDisplay<'_> {585 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {586 for i in self.0 {587 write!(f, "{i}")?;588 }589 Ok(())590 }591}592struct FieldInner {593 full_path: Option<Vec<Index>>,594 session: NixSession,595 value: Option<u32>,596}597fn context(full_path: Option<&[Index]>, query: &str) -> String {598 if let Some(full_path) = &full_path {599 format!("full path: {}", PathDisplay(full_path))600 } else {601 format!("query: {query:?}")602 }603}604#[derive(Clone)]605pub struct Field(Arc<FieldInner>);606impl Field {607 fn root(session: NixSession) -> Self {608 Self(Arc::new(FieldInner {609 full_path: Some(vec![]),610 session,611 value: None,612 }))613 }614 async fn new(session: NixSession, query: &str) -> Result<Self> {615 let vid = session616 .0617 .lock()618 .await619 .execute_assign(query)620 .await621 .with_context(|| context(None, query))?;622 Ok(Self(Arc::new(FieldInner {623 full_path: None,624 session,625 value: Some(vid),626 })))627 }628 pub async fn field(session: NixSession, field: &str) -> Result<Self> {629 Self::root(session).select([Index::var(field)]).await630 }631 pub async fn get_json_deep<'a, V: DeserializeOwned>(632 &self,633 name: impl IntoIterator<Item = Index>,634 ) -> Result<V> {635 let field = self.select(name).await?;636 field.as_json().await637 }638 pub async fn select<'a>(&self, name: impl IntoIterator<Item = Index>) -> Result<Self> {639 let mut used_fields = Vec::new();640 let mut name = name.into_iter();641642 let mut full_path = self.0.full_path.clone();643 let mut query = if let Some(id) = self.0.value {644 format!("sess_field_{id}")645 } else {646 let first = name.next();647 if let Some(Index::Var(i)) = first {648 if let Some(full_path) = &mut full_path {649 full_path.push(Index::Var(i.clone()));650 }651 i.clone()652 } else {653 panic!("first path item should be variable, got {first:?}")654 }655 };656 for v in name {657 if let Some(full_path) = &mut full_path {658 full_path.push(v.clone());659 }660 match v {661 Index::Var(_) => panic!("var item may only be first"),662 Index::String(s) => {663 let escaped = nixlike::serialize(s)?;664 query.push('.');665 query.push_str(escaped.trim());666 }667 Index::Apply(a) => {668 669 query = format!("({query} {a})");670 }671 Index::Expr(e) => {672 let index = Field::new(self.0.session.clone(), &e.out).await?;673 used_fields.push(index.clone());674 query.push('.');675 let index = format!("${{sess_field_{}}}", index.0.value.expect("value"));676 query.push_str(&index);677 }678 Index::ExprApply(e) => {679 let index = Field::new(self.0.session.clone(), &e.out).await?;680 used_fields.push(index.clone());681 query.push(' ');682 let index = format!("sess_field_{}", index.0.value.expect("value"));683 query.push_str(&index);684 query = format!("({query})");685 }686 }687 }688689 let vid = self690 .0691 .session692 .0693 .lock()694 .await695 .execute_assign(&query)696 .await697 .with_context(|| {698 if let Some(full_path) = &full_path {699 format!("full path: {}", PathDisplay(full_path))700 } else {701 format!("query: {query:?}")702 }703 })?;704 Ok(Self(Arc::new(FieldInner {705 full_path,706 session: self.0.session.clone(),707 value: Some(vid),708 })))709 }710 pub async fn as_json<V: DeserializeOwned>(&self) -> Result<V> {711 let id = self.0.value.expect("can't serialize root field");712 let query = format!("sess_field_{id}");713 self.0714 .session715 .0716 .lock()717 .await718 .execute_expression_to_json(&query)719 .await720 .with_context(|| context(self.0.full_path.as_deref(), &query))721 }722 pub async fn list_fields(&self) -> Result<Vec<String>> {723 let id = self.0.value.expect("can't list root fields");724 let query = format!("builtins.attrNames sess_field_{id}");725 self.0726 .session727 .0728 .lock()729 .await730 .execute_expression_to_json(&query)731 .await732 .with_context(|| context(self.0.full_path.as_deref(), &query))733 }734 pub async fn build(&self) -> Result<HashMap<String, PathBuf>> {735 let id = self.0.value.expect("can't use build on not-value");736 let query = format!(":b sess_field_{id}");737 let vid = self738 .0739 .session740 .0741 .lock()742 .await743 .execute_expression_raw(&query, &mut NixHandler::default())744 .await?;745 ensure!(746 !vid.is_empty(),747 "build failed: {}",748 context(self.0.full_path.as_deref(), &query),749 );750 let Some(vid) = vid.strip_prefix("This derivation produced the following outputs:\n")751 else {752 panic!("unexpected build output: {vid:?}");753 };754 let outputs = vid755 .split('\n')756 .filter(|v| !v.is_empty())757 .map(|v| v.split_once(" -> ").expect("unexpected build output"))758 .map(|(a, b)| (a.trim_start().to_owned(), PathBuf::from(b)))759 .collect();760 Ok(outputs)761 }762}763impl Drop for FieldInner {764 fn drop(&mut self) {765 if let Some(id) = self.value {766 if let Ok(mut lock) = self.session.0.try_lock() {767 lock.free_list.push(id)768 }769 770 }771 }772}773struct NixSessionPoolInner {774 flake: OsString,775 nix_args: Vec<OsString>,776}777778#[derive(Debug)]779pub struct NixPoolError(anyhow::Error);780impl From<anyhow::Error> for NixPoolError {781 fn from(value: anyhow::Error) -> Self {782 Self(value)783 }784}785impl std::error::Error for NixPoolError {}786impl std::fmt::Display for NixPoolError {787 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {788 self.0.fmt(f)789 }790}791impl r2d2::ManageConnection for NixSessionPoolInner {792 type Connection = NixSessionInner;793 type Error = NixPoolError;794 fn connect(&self) -> std::result::Result<Self::Connection, Self::Error> {795 let _v = TOKIO_RUNTIME796 .get()797 .expect("missed tokio runtime init!")798 .enter();799 Ok(futures::executor::block_on(NixSessionInner::new(800 self.flake.as_os_str(),801 self.nix_args.iter().map(OsString::as_os_str),802 ))?)803 }804805 fn is_valid(&self, conn: &mut Self::Connection) -> std::result::Result<(), Self::Error> {806 let _v = TOKIO_RUNTIME807 .get()808 .expect("missed tokio runtime init!")809 .enter();810 let res = futures::executor::block_on(conn.execute_expression_number("2 + 2"))?;811 if res != 4 {812 return Err(anyhow!("sanity check failed").into());813 };814 Ok(())815 }816817 fn has_broken(&self, _conn: &mut Self::Connection) -> bool {818 false819 }820}821pub struct NixSessionPool(Pool<NixSessionPoolInner>);822impl NixSessionPool {823 pub async fn new(flake: OsString, nix_args: Vec<OsString>) -> Result<Self> {824 let inner = tokio::task::block_in_place(|| {825 r2d2::Builder::<NixSessionPoolInner>::new()826 .min_idle(Some(0))827 .build(NixSessionPoolInner { flake, nix_args })828 })?;829 Ok(Self(inner))830 }831 pub async fn get(&self) -> Result<NixSession> {832 let v = tokio::task::block_in_place(|| self.0.get())?;833 Ok(NixSession(Arc::new(tokio::sync::Mutex::new(v))))834 }835}836837pub static TOKIO_RUNTIME: OnceLock<tokio::runtime::Handle> = OnceLock::new();