Line data Source code
1 : //! [`super::VirtualFile`] supports different IO engines.
2 : //!
3 : //! The [`IoEngineKind`] enum identifies them.
4 : //!
5 : //! The choice of IO engine is global.
6 : //! Initialize using [`init`].
7 : //!
8 : //! Then use [`get`] and [`super::OpenOptions`].
9 : //!
10 : //!
11 :
12 : #[cfg(target_os = "linux")]
13 : pub(super) mod tokio_epoll_uring_ext;
14 :
15 : use tokio_epoll_uring::IoBuf;
16 : use tracing::Instrument;
17 :
18 : pub(crate) use super::api::IoEngineKind;
19 : #[derive(Clone, Copy)]
20 : #[repr(u8)]
21 : pub(crate) enum IoEngine {
22 : NotSet,
23 : StdFs,
24 : #[cfg(target_os = "linux")]
25 : TokioEpollUring,
26 : }
27 :
28 : impl From<IoEngineKind> for IoEngine {
29 476 : fn from(value: IoEngineKind) -> Self {
30 476 : match value {
31 238 : IoEngineKind::StdFs => IoEngine::StdFs,
32 : #[cfg(target_os = "linux")]
33 238 : IoEngineKind::TokioEpollUring => IoEngine::TokioEpollUring,
34 : }
35 476 : }
36 : }
37 :
38 : impl TryFrom<u8> for IoEngine {
39 : type Error = u8;
40 :
41 3266218 : fn try_from(value: u8) -> Result<Self, Self::Error> {
42 3266218 : Ok(match value {
43 3266218 : v if v == (IoEngine::NotSet as u8) => IoEngine::NotSet,
44 3265742 : v if v == (IoEngine::StdFs as u8) => IoEngine::StdFs,
45 : #[cfg(target_os = "linux")]
46 1632870 : v if v == (IoEngine::TokioEpollUring as u8) => IoEngine::TokioEpollUring,
47 0 : x => return Err(x),
48 : })
49 3266218 : }
50 : }
51 :
52 : static IO_ENGINE: AtomicU8 = AtomicU8::new(IoEngine::NotSet as u8);
53 :
54 476 : pub(crate) fn set(engine_kind: IoEngineKind) {
55 476 : let engine: IoEngine = engine_kind.into();
56 476 : IO_ENGINE.store(engine as u8, std::sync::atomic::Ordering::Relaxed);
57 476 : #[cfg(not(test))]
58 476 : {
59 476 : let metric = &crate::metrics::virtual_file_io_engine::KIND;
60 476 : metric.reset();
61 476 : metric
62 476 : .with_label_values(&[&format!("{engine_kind}")])
63 476 : .set(1);
64 476 : }
65 476 : }
66 :
67 : #[cfg(not(test))]
68 0 : pub(super) fn init(engine_kind: IoEngineKind) {
69 0 : set(engine_kind);
70 0 : }
71 :
72 : /// Longer-term, this API should only be used by [`super::VirtualFile`].
73 3266218 : pub(crate) fn get() -> IoEngine {
74 3266218 : let cur = IoEngine::try_from(IO_ENGINE.load(Ordering::Relaxed)).unwrap();
75 3266218 : if cfg!(test) {
76 3266218 : let env_var_name = "NEON_PAGESERVER_UNIT_TEST_VIRTUAL_FILE_IOENGINE";
77 3266218 : match cur {
78 : IoEngine::NotSet => {
79 476 : let kind = match std::env::var(env_var_name) {
80 476 : Ok(v) => match v.parse::<IoEngineKind>() {
81 476 : Ok(engine_kind) => engine_kind,
82 0 : Err(e) => {
83 0 : panic!(
84 0 : "invalid VirtualFile io engine for env var {env_var_name}: {e:#}: {v:?}"
85 0 : )
86 : }
87 : },
88 : Err(std::env::VarError::NotPresent) => {
89 : #[cfg(target_os = "linux")]
90 : {
91 0 : IoEngineKind::TokioEpollUring
92 : }
93 : #[cfg(not(target_os = "linux"))]
94 : {
95 : IoEngineKind::StdFs
96 : }
97 : }
98 : Err(std::env::VarError::NotUnicode(_)) => {
99 0 : panic!("env var {env_var_name} is not unicode");
100 : }
101 : };
102 476 : self::set(kind);
103 476 : self::get()
104 : }
105 3265742 : x => x,
106 : }
107 : } else {
108 0 : cur
109 : }
110 3266218 : }
111 :
112 : use std::os::unix::prelude::FileExt;
113 : use std::sync::atomic::{AtomicU8, Ordering};
114 :
115 : use super::owned_buffers_io::io_buf_ext::FullSlice;
116 : use super::owned_buffers_io::slice::SliceMutExt;
117 : use super::{FileGuard, Metadata};
118 :
119 : #[cfg(target_os = "linux")]
120 4 : fn epoll_uring_error_to_std(e: tokio_epoll_uring::Error<std::io::Error>) -> std::io::Error {
121 4 : match e {
122 4 : tokio_epoll_uring::Error::Op(e) => e,
123 0 : tokio_epoll_uring::Error::System(system) => {
124 0 : std::io::Error::new(std::io::ErrorKind::Other, system)
125 : }
126 : }
127 4 : }
128 :
129 : impl IoEngine {
130 967637 : pub(super) async fn read_at<Buf>(
131 967637 : &self,
132 967637 : file_guard: FileGuard,
133 967637 : offset: u64,
134 967637 : mut slice: tokio_epoll_uring::Slice<Buf>,
135 967637 : ) -> (
136 967637 : (FileGuard, tokio_epoll_uring::Slice<Buf>),
137 967637 : std::io::Result<usize>,
138 967637 : )
139 967637 : where
140 967637 : Buf: tokio_epoll_uring::IoBufMut + Send,
141 967637 : {
142 967637 : match self {
143 0 : IoEngine::NotSet => panic!("not initialized"),
144 : IoEngine::StdFs => {
145 483832 : let rust_slice = slice.as_mut_rust_slice_full_zeroed();
146 483832 : let res = file_guard.with_std_file(|std_file| std_file.read_at(rust_slice, offset));
147 483832 : ((file_guard, slice), res)
148 : }
149 : #[cfg(target_os = "linux")]
150 : IoEngine::TokioEpollUring => {
151 483805 : let system = tokio_epoll_uring_ext::thread_local_system().await;
152 483805 : let (resources, res) = system.read(file_guard, offset, slice).await;
153 483805 : (resources, res.map_err(epoll_uring_error_to_std))
154 : }
155 : }
156 967637 : }
157 5650 : pub(super) async fn sync_all(&self, file_guard: FileGuard) -> (FileGuard, std::io::Result<()>) {
158 5650 : match self {
159 0 : IoEngine::NotSet => panic!("not initialized"),
160 : IoEngine::StdFs => {
161 2818 : let res = file_guard.with_std_file(|std_file| std_file.sync_all());
162 2818 : (file_guard, res)
163 : }
164 : #[cfg(target_os = "linux")]
165 : IoEngine::TokioEpollUring => {
166 2832 : let system = tokio_epoll_uring_ext::thread_local_system().await;
167 2832 : let (resources, res) = system.fsync(file_guard).await;
168 2832 : (resources, res.map_err(epoll_uring_error_to_std))
169 : }
170 : }
171 5650 : }
172 0 : pub(super) async fn sync_data(
173 0 : &self,
174 0 : file_guard: FileGuard,
175 0 : ) -> (FileGuard, std::io::Result<()>) {
176 0 : match self {
177 0 : IoEngine::NotSet => panic!("not initialized"),
178 : IoEngine::StdFs => {
179 0 : let res = file_guard.with_std_file(|std_file| std_file.sync_data());
180 0 : (file_guard, res)
181 : }
182 : #[cfg(target_os = "linux")]
183 : IoEngine::TokioEpollUring => {
184 0 : let system = tokio_epoll_uring_ext::thread_local_system().await;
185 0 : let (resources, res) = system.fdatasync(file_guard).await;
186 0 : (resources, res.map_err(epoll_uring_error_to_std))
187 : }
188 : }
189 0 : }
190 3620 : pub(super) async fn metadata(
191 3620 : &self,
192 3620 : file_guard: FileGuard,
193 3620 : ) -> (FileGuard, std::io::Result<Metadata>) {
194 3620 : match self {
195 0 : IoEngine::NotSet => panic!("not initialized"),
196 : IoEngine::StdFs => {
197 1810 : let res =
198 1810 : file_guard.with_std_file(|std_file| std_file.metadata().map(Metadata::from));
199 1810 : (file_guard, res)
200 : }
201 : #[cfg(target_os = "linux")]
202 : IoEngine::TokioEpollUring => {
203 1810 : let system = tokio_epoll_uring_ext::thread_local_system().await;
204 1810 : let (resources, res) = system.statx(file_guard).await;
205 1810 : (
206 1810 : resources,
207 1810 : res.map_err(epoll_uring_error_to_std).map(Metadata::from),
208 1810 : )
209 : }
210 : }
211 3620 : }
212 2274177 : pub(super) async fn write_at<B: IoBuf + Send>(
213 2274177 : &self,
214 2274177 : file_guard: FileGuard,
215 2274177 : offset: u64,
216 2274177 : buf: FullSlice<B>,
217 2274177 : ) -> ((FileGuard, FullSlice<B>), std::io::Result<usize>) {
218 2274177 : match self {
219 0 : IoEngine::NotSet => panic!("not initialized"),
220 : IoEngine::StdFs => {
221 1137090 : let result = file_guard.with_std_file(|std_file| std_file.write_at(&buf, offset));
222 1137090 : ((file_guard, buf), result)
223 : }
224 : #[cfg(target_os = "linux")]
225 : IoEngine::TokioEpollUring => {
226 1137087 : let system = tokio_epoll_uring_ext::thread_local_system().await;
227 1137087 : let ((file_guard, slice), res) =
228 1137087 : system.write(file_guard, offset, buf.into_raw_slice()).await;
229 1137087 : (
230 1137087 : (file_guard, FullSlice::must_new(slice)),
231 1137087 : res.map_err(epoll_uring_error_to_std),
232 1137087 : )
233 : }
234 : }
235 2274177 : }
236 :
237 : /// If we switch a user of [`tokio::fs`] to use [`super::io_engine`],
238 : /// they'd start blocking the executor thread if [`IoEngine::StdFs`] is configured
239 : /// whereas before the switch to [`super::io_engine`], that wasn't the case.
240 : /// This method helps avoid such a regression.
241 : ///
242 : /// Panics if the `spawn_blocking` fails, see [`tokio::task::JoinError`] for reasons why that can happen.
243 28 : pub(crate) async fn spawn_blocking_and_block_on_if_std<Fut, R>(&self, work: Fut) -> R
244 28 : where
245 28 : Fut: 'static + Send + std::future::Future<Output = R>,
246 28 : R: 'static + Send,
247 28 : {
248 28 : match self {
249 0 : IoEngine::NotSet => panic!("not initialized"),
250 : IoEngine::StdFs => {
251 14 : let span = tracing::info_span!("spawn_blocking_block_on_if_std");
252 14 : tokio::task::spawn_blocking({
253 14 : move || tokio::runtime::Handle::current().block_on(work.instrument(span))
254 14 : })
255 14 : .await
256 14 : .expect("failed to join blocking code most likely it panicked, panicking as well")
257 : }
258 : #[cfg(target_os = "linux")]
259 14 : IoEngine::TokioEpollUring => work.await,
260 : }
261 28 : }
262 : }
263 :
264 : pub enum FeatureTestResult {
265 : PlatformPreferred(IoEngineKind),
266 : Worse {
267 : engine: IoEngineKind,
268 : remark: String,
269 : },
270 : }
271 :
272 : impl FeatureTestResult {
273 : #[cfg(target_os = "linux")]
274 : const PLATFORM_PREFERRED: IoEngineKind = IoEngineKind::TokioEpollUring;
275 : #[cfg(not(target_os = "linux"))]
276 : const PLATFORM_PREFERRED: IoEngineKind = IoEngineKind::StdFs;
277 : }
278 :
279 : impl From<FeatureTestResult> for IoEngineKind {
280 0 : fn from(val: FeatureTestResult) -> Self {
281 0 : match val {
282 0 : FeatureTestResult::PlatformPreferred(e) => e,
283 0 : FeatureTestResult::Worse { engine, .. } => engine,
284 : }
285 0 : }
286 : }
287 :
288 : /// Somewhat costly under the hood, do only once.
289 : /// Panics if we can't set up the feature test.
290 488 : pub fn feature_test() -> anyhow::Result<FeatureTestResult> {
291 488 : std::thread::spawn(|| {
292 488 :
293 488 : #[cfg(not(target_os = "linux"))]
294 488 : {
295 488 : Ok(FeatureTestResult::PlatformPreferred(
296 488 : FeatureTestResult::PLATFORM_PREFERRED,
297 488 : ))
298 488 : }
299 488 : #[cfg(target_os = "linux")]
300 488 : {
301 488 : let rt = tokio::runtime::Builder::new_current_thread()
302 488 : .enable_all()
303 488 : .build()
304 488 : .unwrap();
305 488 : Ok(match rt.block_on(tokio_epoll_uring::System::launch()) {
306 : Ok(_) => FeatureTestResult::PlatformPreferred({
307 488 : assert!(matches!(
308 488 : IoEngineKind::TokioEpollUring,
309 : FeatureTestResult::PLATFORM_PREFERRED
310 : ));
311 488 : FeatureTestResult::PLATFORM_PREFERRED
312 : }),
313 0 : Err(tokio_epoll_uring::LaunchResult::IoUringBuild(e)) => {
314 0 : let remark = match e.raw_os_error() {
315 : Some(nix::libc::EPERM) => {
316 : // fall back
317 0 : "creating tokio-epoll-uring fails with EPERM, assuming it's admin-disabled "
318 0 : .to_string()
319 : }
320 : Some(nix::libc::EFAULT) => {
321 : // fail feature test
322 0 : anyhow::bail!(
323 0 : "creating tokio-epoll-uring fails with EFAULT, might have corrupted memory"
324 0 : );
325 : }
326 : Some(_) | None => {
327 : // fall back
328 0 : format!("creating tokio-epoll-uring fails with error: {e:#}")
329 : }
330 : };
331 0 : FeatureTestResult::Worse {
332 0 : engine: IoEngineKind::StdFs,
333 0 : remark,
334 0 : }
335 : }
336 : })
337 : }
338 488 : })
339 488 : .join()
340 488 : .unwrap()
341 488 : }
342 :
343 : /// For use in benchmark binaries only.
344 : ///
345 : /// Benchmarks which initialize `virtual_file` need to know what engine to use, but we also
346 : /// don't want to silently fall back to slower I/O engines in a benchmark: this could waste
347 : /// developer time trying to figure out why it's slow.
348 : ///
349 : /// In practice, this method will either return IoEngineKind::TokioEpollUring, or panic.
350 0 : pub fn io_engine_for_bench() -> IoEngineKind {
351 0 : #[cfg(not(target_os = "linux"))]
352 0 : {
353 0 : panic!("This benchmark does I/O and can only give a representative result on Linux");
354 0 : }
355 0 : #[cfg(target_os = "linux")]
356 0 : {
357 0 : match feature_test().unwrap() {
358 0 : FeatureTestResult::PlatformPreferred(engine) => engine,
359 : FeatureTestResult::Worse {
360 0 : engine: _engine,
361 0 : remark,
362 0 : } => {
363 0 : panic!("This benchmark does I/O can requires the preferred I/O engine: {remark}");
364 : }
365 : }
366 : }
367 0 : }
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