Line data Source code
1 : //! VirtualFile is like a normal File, but it's not bound directly to
2 : //! a file descriptor.
3 : //!
4 : //! Instead, the file is opened when it's read from,
5 : //! and if too many files are open globally in the system, least-recently
6 : //! used ones are closed.
7 : //!
8 : //! To track which files have been recently used, we use the clock algorithm
9 : //! with a 'recently_used' flag on each slot.
10 : //!
11 : //! This is similar to PostgreSQL's virtual file descriptor facility in
12 : //! src/backend/storage/file/fd.c
13 : //!
14 : use crate::context::RequestContext;
15 : use crate::metrics::{StorageIoOperation, STORAGE_IO_SIZE, STORAGE_IO_TIME_METRIC};
16 :
17 : use crate::page_cache::{PageWriteGuard, PAGE_SZ};
18 : use crate::tenant::TENANTS_SEGMENT_NAME;
19 : use camino::{Utf8Path, Utf8PathBuf};
20 : use once_cell::sync::OnceCell;
21 : use owned_buffers_io::aligned_buffer::buffer::AlignedBuffer;
22 : use owned_buffers_io::aligned_buffer::{AlignedBufferMut, AlignedSlice, ConstAlign};
23 : use owned_buffers_io::io_buf_aligned::{IoBufAligned, IoBufAlignedMut};
24 : use owned_buffers_io::io_buf_ext::FullSlice;
25 : use pageserver_api::config::defaults::DEFAULT_IO_BUFFER_ALIGNMENT;
26 : use pageserver_api::shard::TenantShardId;
27 : use std::fs::File;
28 : use std::io::{Error, ErrorKind, Seek, SeekFrom};
29 : #[cfg(target_os = "linux")]
30 : use std::os::unix::fs::OpenOptionsExt;
31 : use tokio_epoll_uring::{BoundedBuf, IoBuf, IoBufMut, Slice};
32 :
33 : use std::os::fd::{AsRawFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
34 : use std::sync::atomic::{AtomicBool, AtomicU8, AtomicUsize, Ordering};
35 : use tokio::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
36 : use tokio::time::Instant;
37 :
38 : pub use pageserver_api::models::virtual_file as api;
39 : pub(crate) mod io_engine;
40 : pub use io_engine::feature_test as io_engine_feature_test;
41 : pub use io_engine::io_engine_for_bench;
42 : pub use io_engine::FeatureTestResult as IoEngineFeatureTestResult;
43 : mod metadata;
44 : mod open_options;
45 : use self::owned_buffers_io::write::OwnedAsyncWriter;
46 : pub(crate) use api::IoMode;
47 : pub(crate) use io_engine::IoEngineKind;
48 : pub(crate) use metadata::Metadata;
49 : pub(crate) use open_options::*;
50 :
51 : pub(crate) mod owned_buffers_io {
52 : //! Abstractions for IO with owned buffers.
53 : //!
54 : //! Not actually tied to [`crate::virtual_file`] specifically, but, it's the primary
55 : //! reason we need this abstraction.
56 : //!
57 : //! Over time, this could move into the `tokio-epoll-uring` crate, maybe `uring-common`,
58 : //! but for the time being we're proving out the primitives in the neon.git repo
59 : //! for faster iteration.
60 :
61 : pub(crate) mod aligned_buffer;
62 : pub(crate) mod io_buf_aligned;
63 : pub(crate) mod io_buf_ext;
64 : pub(crate) mod slice;
65 : pub(crate) mod write;
66 : }
67 :
68 : #[derive(Debug)]
69 : pub struct VirtualFile {
70 : inner: VirtualFileInner,
71 : _mode: IoMode,
72 : }
73 :
74 : impl VirtualFile {
75 : /// Open a file in read-only mode. Like File::open.
76 1048 : pub async fn open<P: AsRef<Utf8Path>>(
77 1048 : path: P,
78 1048 : ctx: &RequestContext,
79 1048 : ) -> Result<Self, std::io::Error> {
80 1048 : let inner = VirtualFileInner::open(path, ctx).await?;
81 1048 : Ok(VirtualFile {
82 1048 : inner,
83 1048 : _mode: IoMode::Buffered,
84 1048 : })
85 1048 : }
86 :
87 : /// Open a file in read-only mode. Like File::open.
88 : ///
89 : /// `O_DIRECT` will be enabled base on `virtual_file_io_mode`.
90 1228 : pub async fn open_v2<P: AsRef<Utf8Path>>(
91 1228 : path: P,
92 1228 : ctx: &RequestContext,
93 1228 : ) -> Result<Self, std::io::Error> {
94 1228 : Self::open_with_options_v2(path.as_ref(), OpenOptions::new().read(true), ctx).await
95 1228 : }
96 :
97 1509 : pub async fn create<P: AsRef<Utf8Path>>(
98 1509 : path: P,
99 1509 : ctx: &RequestContext,
100 1509 : ) -> Result<Self, std::io::Error> {
101 1509 : let inner = VirtualFileInner::create(path, ctx).await?;
102 1509 : Ok(VirtualFile {
103 1509 : inner,
104 1509 : _mode: IoMode::Buffered,
105 1509 : })
106 1509 : }
107 :
108 0 : pub async fn create_v2<P: AsRef<Utf8Path>>(
109 0 : path: P,
110 0 : ctx: &RequestContext,
111 0 : ) -> Result<Self, std::io::Error> {
112 0 : VirtualFile::open_with_options_v2(
113 0 : path.as_ref(),
114 0 : OpenOptions::new().write(true).create(true).truncate(true),
115 0 : ctx,
116 0 : )
117 0 : .await
118 0 : }
119 :
120 740 : pub async fn open_with_options<P: AsRef<Utf8Path>>(
121 740 : path: P,
122 740 : open_options: &OpenOptions,
123 740 : ctx: &RequestContext, /* TODO: carry a pointer to the metrics in the RequestContext instead of the parsing https://github.com/neondatabase/neon/issues/6107 */
124 740 : ) -> Result<Self, std::io::Error> {
125 740 : let inner = VirtualFileInner::open_with_options(path, open_options, ctx).await?;
126 740 : Ok(VirtualFile {
127 740 : inner,
128 740 : _mode: IoMode::Buffered,
129 740 : })
130 740 : }
131 :
132 2508 : pub async fn open_with_options_v2<P: AsRef<Utf8Path>>(
133 2508 : path: P,
134 2508 : open_options: &OpenOptions,
135 2508 : ctx: &RequestContext, /* TODO: carry a pointer to the metrics in the RequestContext instead of the parsing https://github.com/neondatabase/neon/issues/6107 */
136 2508 : ) -> Result<Self, std::io::Error> {
137 2508 : let file = match get_io_mode() {
138 : IoMode::Buffered => {
139 2508 : let inner = VirtualFileInner::open_with_options(path, open_options, ctx).await?;
140 2508 : VirtualFile {
141 2508 : inner,
142 2508 : _mode: IoMode::Buffered,
143 2508 : }
144 : }
145 : #[cfg(target_os = "linux")]
146 : IoMode::Direct => {
147 0 : let inner = VirtualFileInner::open_with_options(
148 0 : path,
149 0 : open_options.clone().custom_flags(nix::libc::O_DIRECT),
150 0 : ctx,
151 0 : )
152 0 : .await?;
153 0 : VirtualFile {
154 0 : inner,
155 0 : _mode: IoMode::Direct,
156 0 : }
157 : }
158 : };
159 2508 : Ok(file)
160 2508 : }
161 :
162 1162 : pub fn path(&self) -> &Utf8Path {
163 1162 : self.inner.path.as_path()
164 1162 : }
165 :
166 22 : pub async fn crashsafe_overwrite<B: BoundedBuf<Buf = Buf> + Send, Buf: IoBuf + Send>(
167 22 : final_path: Utf8PathBuf,
168 22 : tmp_path: Utf8PathBuf,
169 22 : content: B,
170 22 : ) -> std::io::Result<()> {
171 22 : VirtualFileInner::crashsafe_overwrite(final_path, tmp_path, content).await
172 22 : }
173 :
174 2773 : pub async fn sync_all(&self) -> Result<(), Error> {
175 2773 : if SYNC_MODE.load(std::sync::atomic::Ordering::Relaxed) == SyncMode::UnsafeNoSync as u8 {
176 0 : return Ok(());
177 2773 : }
178 2773 : self.inner.sync_all().await
179 2773 : }
180 :
181 0 : pub async fn sync_data(&self) -> Result<(), Error> {
182 0 : if SYNC_MODE.load(std::sync::atomic::Ordering::Relaxed) == SyncMode::UnsafeNoSync as u8 {
183 0 : return Ok(());
184 0 : }
185 0 : self.inner.sync_data().await
186 0 : }
187 :
188 1770 : pub async fn metadata(&self) -> Result<Metadata, Error> {
189 1770 : self.inner.metadata().await
190 1770 : }
191 :
192 232 : pub fn remove(self) {
193 232 : self.inner.remove();
194 232 : }
195 :
196 5554 : pub async fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error> {
197 5554 : self.inner.seek(pos).await
198 5554 : }
199 :
200 223094 : pub async fn read_exact_at<Buf>(
201 223094 : &self,
202 223094 : slice: Slice<Buf>,
203 223094 : offset: u64,
204 223094 : ctx: &RequestContext,
205 223094 : ) -> Result<Slice<Buf>, Error>
206 223094 : where
207 223094 : Buf: IoBufAlignedMut + Send,
208 223094 : {
209 223094 : self.inner.read_exact_at(slice, offset, ctx).await
210 223094 : }
211 :
212 32163 : pub async fn read_exact_at_page(
213 32163 : &self,
214 32163 : page: PageWriteGuard<'static>,
215 32163 : offset: u64,
216 32163 : ctx: &RequestContext,
217 32163 : ) -> Result<PageWriteGuard<'static>, Error> {
218 32163 : self.inner.read_exact_at_page(page, offset, ctx).await
219 32163 : }
220 :
221 6607 : pub async fn write_all_at<Buf: IoBufAligned + Send>(
222 6607 : &self,
223 6607 : buf: FullSlice<Buf>,
224 6607 : offset: u64,
225 6607 : ctx: &RequestContext,
226 6607 : ) -> (FullSlice<Buf>, Result<(), Error>) {
227 6607 : self.inner.write_all_at(buf, offset, ctx).await
228 6607 : }
229 :
230 1129950 : pub async fn write_all<Buf: IoBuf + Send>(
231 1129950 : &mut self,
232 1129950 : buf: FullSlice<Buf>,
233 1129950 : ctx: &RequestContext,
234 1129950 : ) -> (FullSlice<Buf>, Result<usize, Error>) {
235 1129950 : self.inner.write_all(buf, ctx).await
236 1129950 : }
237 : }
238 :
239 : /// Indicates whether to enable fsync, fdatasync, or O_SYNC/O_DSYNC when writing
240 : /// files. Switching this off is unsafe and only used for testing on machines
241 : /// with slow drives.
242 : #[repr(u8)]
243 : pub enum SyncMode {
244 : Sync,
245 : UnsafeNoSync,
246 : }
247 :
248 : impl TryFrom<u8> for SyncMode {
249 : type Error = u8;
250 :
251 0 : fn try_from(value: u8) -> Result<Self, Self::Error> {
252 0 : Ok(match value {
253 0 : v if v == (SyncMode::Sync as u8) => SyncMode::Sync,
254 0 : v if v == (SyncMode::UnsafeNoSync as u8) => SyncMode::UnsafeNoSync,
255 0 : x => return Err(x),
256 : })
257 0 : }
258 : }
259 :
260 : ///
261 : /// A virtual file descriptor. You can use this just like std::fs::File, but internally
262 : /// the underlying file is closed if the system is low on file descriptors,
263 : /// and re-opened when it's accessed again.
264 : ///
265 : /// Like with std::fs::File, multiple threads can read/write the file concurrently,
266 : /// holding just a shared reference the same VirtualFile, using the read_at() / write_at()
267 : /// functions from the FileExt trait. But the functions from the Read/Write/Seek traits
268 : /// require a mutable reference, because they modify the "current position".
269 : ///
270 : /// Each VirtualFile has a physical file descriptor in the global OPEN_FILES array, at the
271 : /// slot that 'handle points to, if the underlying file is currently open. If it's not
272 : /// currently open, the 'handle' can still point to the slot where it was last kept. The
273 : /// 'tag' field is used to detect whether the handle still is valid or not.
274 : ///
275 : #[derive(Debug)]
276 : pub struct VirtualFileInner {
277 : /// Lazy handle to the global file descriptor cache. The slot that this points to
278 : /// might contain our File, or it may be empty, or it may contain a File that
279 : /// belongs to a different VirtualFile.
280 : handle: RwLock<SlotHandle>,
281 :
282 : /// Current file position
283 : pos: u64,
284 :
285 : /// File path and options to use to open it.
286 : ///
287 : /// Note: this only contains the options needed to re-open it. For example,
288 : /// if a new file is created, we only pass the create flag when it's initially
289 : /// opened, in the VirtualFile::create() function, and strip the flag before
290 : /// storing it here.
291 : pub path: Utf8PathBuf,
292 : open_options: OpenOptions,
293 :
294 : // These are strings becase we only use them for metrics, and those expect strings.
295 : // It makes no sense for us to constantly turn the `TimelineId` and `TenantId` into
296 : // strings.
297 : tenant_id: String,
298 : shard_id: String,
299 : timeline_id: String,
300 : }
301 :
302 : #[derive(Debug, PartialEq, Clone, Copy)]
303 : struct SlotHandle {
304 : /// Index into OPEN_FILES.slots
305 : index: usize,
306 :
307 : /// Value of 'tag' in the slot. If slot's tag doesn't match, then the slot has
308 : /// been recycled and no longer contains the FD for this virtual file.
309 : tag: u64,
310 : }
311 :
312 : /// OPEN_FILES is the global array that holds the physical file descriptors that
313 : /// are currently open. Each slot in the array is protected by a separate lock,
314 : /// so that different files can be accessed independently. The lock must be held
315 : /// in write mode to replace the slot with a different file, but a read mode
316 : /// is enough to operate on the file, whether you're reading or writing to it.
317 : ///
318 : /// OPEN_FILES starts in uninitialized state, and it's initialized by
319 : /// the virtual_file::init() function. It must be called exactly once at page
320 : /// server startup.
321 : static OPEN_FILES: OnceCell<OpenFiles> = OnceCell::new();
322 :
323 : struct OpenFiles {
324 : slots: &'static [Slot],
325 :
326 : /// clock arm for the clock algorithm
327 : next: AtomicUsize,
328 : }
329 :
330 : struct Slot {
331 : inner: RwLock<SlotInner>,
332 :
333 : /// has this file been used since last clock sweep?
334 : recently_used: AtomicBool,
335 : }
336 :
337 : struct SlotInner {
338 : /// Counter that's incremented every time a different file is stored here.
339 : /// To avoid the ABA problem.
340 : tag: u64,
341 :
342 : /// the underlying file
343 : file: Option<OwnedFd>,
344 : }
345 :
346 : /// Impl of [`tokio_epoll_uring::IoBuf`] and [`tokio_epoll_uring::IoBufMut`] for [`PageWriteGuard`].
347 : struct PageWriteGuardBuf {
348 : page: PageWriteGuard<'static>,
349 : }
350 : // Safety: the [`PageWriteGuard`] gives us exclusive ownership of the page cache slot,
351 : // and the location remains stable even if [`Self`] or the [`PageWriteGuard`] is moved.
352 : // Page cache pages are zero-initialized, so, wrt uninitialized memory we're good.
353 : // (Page cache tracks separately whether the contents are valid, see `PageWriteGuard::mark_valid`.)
354 : unsafe impl tokio_epoll_uring::IoBuf for PageWriteGuardBuf {
355 128747 : fn stable_ptr(&self) -> *const u8 {
356 128747 : self.page.as_ptr()
357 128747 : }
358 241365 : fn bytes_init(&self) -> usize {
359 241365 : self.page.len()
360 241365 : }
361 96489 : fn bytes_total(&self) -> usize {
362 96489 : self.page.len()
363 96489 : }
364 : }
365 : // Safety: see above, plus: the ownership of [`PageWriteGuard`] means exclusive access,
366 : // hence it's safe to hand out the `stable_mut_ptr()`.
367 : unsafe impl tokio_epoll_uring::IoBufMut for PageWriteGuardBuf {
368 48292 : fn stable_mut_ptr(&mut self) -> *mut u8 {
369 48292 : self.page.as_mut_ptr()
370 48292 : }
371 :
372 32163 : unsafe fn set_init(&mut self, pos: usize) {
373 32163 : // There shouldn't really be any reason to call this API since bytes_init() == bytes_total().
374 32163 : assert!(pos <= self.page.len());
375 32163 : }
376 : }
377 :
378 : impl OpenFiles {
379 : /// Find a slot to use, evicting an existing file descriptor if needed.
380 : ///
381 : /// On return, we hold a lock on the slot, and its 'tag' has been updated
382 : /// recently_used has been set. It's all ready for reuse.
383 192480 : async fn find_victim_slot(&self) -> (SlotHandle, RwLockWriteGuard<SlotInner>) {
384 192480 : //
385 192480 : // Run the clock algorithm to find a slot to replace.
386 192480 : //
387 192480 : let num_slots = self.slots.len();
388 192480 : let mut retries = 0;
389 : let mut slot;
390 : let mut slot_guard;
391 : let index;
392 : loop {
393 2283716 : let next = self.next.fetch_add(1, Ordering::AcqRel) % num_slots;
394 2283716 : slot = &self.slots[next];
395 2283716 :
396 2283716 : // If the recently_used flag on this slot is set, continue the clock
397 2283716 : // sweep. Otherwise try to use this slot. If we cannot acquire the
398 2283716 : // lock, also continue the clock sweep.
399 2283716 : //
400 2283716 : // We only continue in this manner for a while, though. If we loop
401 2283716 : // through the array twice without finding a victim, just pick the
402 2283716 : // next slot and wait until we can reuse it. This way, we avoid
403 2283716 : // spinning in the extreme case that all the slots are busy with an
404 2283716 : // I/O operation.
405 2283716 : if retries < num_slots * 2 {
406 2197831 : if !slot.recently_used.swap(false, Ordering::Release) {
407 1990768 : if let Ok(guard) = slot.inner.try_write() {
408 106595 : slot_guard = guard;
409 106595 : index = next;
410 106595 : break;
411 1884173 : }
412 207063 : }
413 2091236 : retries += 1;
414 : } else {
415 85885 : slot_guard = slot.inner.write().await;
416 85885 : index = next;
417 85885 : break;
418 : }
419 : }
420 :
421 : //
422 : // We now have the victim slot locked. If it was in use previously, close the
423 : // old file.
424 : //
425 192480 : if let Some(old_file) = slot_guard.file.take() {
426 187603 : // the normal path of dropping VirtualFile uses "close", use "close-by-replace" here to
427 187603 : // distinguish the two.
428 187603 : STORAGE_IO_TIME_METRIC
429 187603 : .get(StorageIoOperation::CloseByReplace)
430 187603 : .observe_closure_duration(|| drop(old_file));
431 187603 : }
432 :
433 : // Prepare the slot for reuse and return it
434 192480 : slot_guard.tag += 1;
435 192480 : slot.recently_used.store(true, Ordering::Relaxed);
436 192480 : (
437 192480 : SlotHandle {
438 192480 : index,
439 192480 : tag: slot_guard.tag,
440 192480 : },
441 192480 : slot_guard,
442 192480 : )
443 192480 : }
444 : }
445 :
446 : /// Identify error types that should alwways terminate the process. Other
447 : /// error types may be elegible for retry.
448 2 : pub(crate) fn is_fatal_io_error(e: &std::io::Error) -> bool {
449 : use nix::errno::Errno::*;
450 2 : match e.raw_os_error().map(nix::errno::from_i32) {
451 : Some(EIO) => {
452 : // Terminate on EIO because we no longer trust the device to store
453 : // data safely, or to uphold persistence guarantees on fsync.
454 0 : true
455 : }
456 : Some(EROFS) => {
457 : // Terminate on EROFS because a filesystem is usually remounted
458 : // readonly when it has experienced some critical issue, so the same
459 : // logic as EIO applies.
460 0 : true
461 : }
462 : Some(EACCES) => {
463 : // Terminate on EACCESS because we should always have permissions
464 : // for our own data dir: if we don't, then we can't do our job and
465 : // need administrative intervention to fix permissions. Terminating
466 : // is the best way to make sure we stop cleanly rather than going
467 : // into infinite retry loops, and will make it clear to the outside
468 : // world that we need help.
469 0 : true
470 : }
471 : _ => {
472 : // Treat all other local file I/O errors are retryable. This includes:
473 : // - ENOSPC: we stay up and wait for eviction to free some space
474 : // - EINVAL, EBADF, EBADFD: this is a code bug, not a filesystem/hardware issue
475 : // - WriteZero, Interrupted: these are used internally VirtualFile
476 2 : false
477 : }
478 : }
479 2 : }
480 :
481 : /// Call this when the local filesystem gives us an error with an external
482 : /// cause: this includes EIO, EROFS, and EACCESS: all these indicate either
483 : /// bad storage or bad configuration, and we can't fix that from inside
484 : /// a running process.
485 0 : pub(crate) fn on_fatal_io_error(e: &std::io::Error, context: &str) -> ! {
486 0 : tracing::error!("Fatal I/O error: {e}: {context})");
487 0 : std::process::abort();
488 : }
489 :
490 : pub(crate) trait MaybeFatalIo<T> {
491 : fn maybe_fatal_err(self, context: &str) -> std::io::Result<T>;
492 : fn fatal_err(self, context: &str) -> T;
493 : }
494 :
495 : impl<T> MaybeFatalIo<T> for std::io::Result<T> {
496 : /// Terminate the process if the result is an error of a fatal type, else pass it through
497 : ///
498 : /// This is appropriate for writes, where we typically want to die on EIO/ACCES etc, but
499 : /// not on ENOSPC.
500 1141119 : fn maybe_fatal_err(self, context: &str) -> std::io::Result<T> {
501 1141119 : if let Err(e) = &self {
502 2 : if is_fatal_io_error(e) {
503 0 : on_fatal_io_error(e, context);
504 2 : }
505 1141117 : }
506 1141119 : self
507 1141119 : }
508 :
509 : /// Terminate the process on any I/O error.
510 : ///
511 : /// This is appropriate for reads on files that we know exist: they should always work.
512 2042 : fn fatal_err(self, context: &str) -> T {
513 2042 : match self {
514 2042 : Ok(v) => v,
515 0 : Err(e) => {
516 0 : on_fatal_io_error(&e, context);
517 : }
518 : }
519 2042 : }
520 : }
521 :
522 : /// Observe duration for the given storage I/O operation
523 : ///
524 : /// Unlike `observe_closure_duration`, this supports async,
525 : /// where "support" means that we measure wall clock time.
526 : macro_rules! observe_duration {
527 : ($op:expr, $($body:tt)*) => {{
528 : let instant = Instant::now();
529 : let result = $($body)*;
530 : let elapsed = instant.elapsed().as_secs_f64();
531 : STORAGE_IO_TIME_METRIC
532 : .get($op)
533 : .observe(elapsed);
534 : result
535 : }}
536 : }
537 :
538 : macro_rules! with_file {
539 : ($this:expr, $op:expr, | $ident:ident | $($body:tt)*) => {{
540 : let $ident = $this.lock_file().await?;
541 : observe_duration!($op, $($body)*)
542 : }};
543 : ($this:expr, $op:expr, | mut $ident:ident | $($body:tt)*) => {{
544 : let mut $ident = $this.lock_file().await?;
545 : observe_duration!($op, $($body)*)
546 : }};
547 : }
548 :
549 : impl VirtualFileInner {
550 : /// Open a file in read-only mode. Like File::open.
551 1048 : pub async fn open<P: AsRef<Utf8Path>>(
552 1048 : path: P,
553 1048 : ctx: &RequestContext,
554 1048 : ) -> Result<VirtualFileInner, std::io::Error> {
555 1048 : Self::open_with_options(path.as_ref(), OpenOptions::new().read(true), ctx).await
556 1048 : }
557 :
558 : /// Create a new file for writing. If the file exists, it will be truncated.
559 : /// Like File::create.
560 1509 : pub async fn create<P: AsRef<Utf8Path>>(
561 1509 : path: P,
562 1509 : ctx: &RequestContext,
563 1509 : ) -> Result<VirtualFileInner, std::io::Error> {
564 1509 : Self::open_with_options(
565 1509 : path.as_ref(),
566 1509 : OpenOptions::new().write(true).create(true).truncate(true),
567 1509 : ctx,
568 1509 : )
569 1509 : .await
570 1509 : }
571 :
572 : /// Open a file with given options.
573 : ///
574 : /// Note: If any custom flags were set in 'open_options' through OpenOptionsExt,
575 : /// they will be applied also when the file is subsequently re-opened, not only
576 : /// on the first time. Make sure that's sane!
577 6005 : pub async fn open_with_options<P: AsRef<Utf8Path>>(
578 6005 : path: P,
579 6005 : open_options: &OpenOptions,
580 6005 : _ctx: &RequestContext, /* TODO: carry a pointer to the metrics in the RequestContext instead of the parsing https://github.com/neondatabase/neon/issues/6107 */
581 6005 : ) -> Result<VirtualFileInner, std::io::Error> {
582 6005 : let path_ref = path.as_ref();
583 6005 : let path_str = path_ref.to_string();
584 6005 : let parts = path_str.split('/').collect::<Vec<&str>>();
585 6005 : let (tenant_id, shard_id, timeline_id) =
586 6005 : if parts.len() > 5 && parts[parts.len() - 5] == TENANTS_SEGMENT_NAME {
587 4511 : let tenant_shard_part = parts[parts.len() - 4];
588 4511 : let (tenant_id, shard_id) = match tenant_shard_part.parse::<TenantShardId>() {
589 4511 : Ok(tenant_shard_id) => (
590 4511 : tenant_shard_id.tenant_id.to_string(),
591 4511 : format!("{}", tenant_shard_id.shard_slug()),
592 4511 : ),
593 : Err(_) => {
594 : // Malformed path: this ID is just for observability, so tolerate it
595 : // and pass through
596 0 : (tenant_shard_part.to_string(), "*".to_string())
597 : }
598 : };
599 4511 : (tenant_id, shard_id, parts[parts.len() - 2].to_string())
600 : } else {
601 1494 : ("*".to_string(), "*".to_string(), "*".to_string())
602 : };
603 6005 : let (handle, mut slot_guard) = get_open_files().find_victim_slot().await;
604 :
605 : // NB: there is also StorageIoOperation::OpenAfterReplace which is for the case
606 : // where our caller doesn't get to use the returned VirtualFile before its
607 : // slot gets re-used by someone else.
608 6005 : let file = observe_duration!(StorageIoOperation::Open, {
609 6005 : open_options.open(path_ref.as_std_path()).await?
610 : });
611 :
612 : // Strip all options other than read and write.
613 : //
614 : // It would perhaps be nicer to check just for the read and write flags
615 : // explicitly, but OpenOptions doesn't contain any functions to read flags,
616 : // only to set them.
617 6005 : let mut reopen_options = open_options.clone();
618 6005 : reopen_options.create(false);
619 6005 : reopen_options.create_new(false);
620 6005 : reopen_options.truncate(false);
621 6005 :
622 6005 : let vfile = VirtualFileInner {
623 6005 : handle: RwLock::new(handle),
624 6005 : pos: 0,
625 6005 : path: path_ref.to_path_buf(),
626 6005 : open_options: reopen_options,
627 6005 : tenant_id,
628 6005 : shard_id,
629 6005 : timeline_id,
630 6005 : };
631 6005 :
632 6005 : // TODO: Under pressure, it's likely the slot will get re-used and
633 6005 : // the underlying file closed before they get around to using it.
634 6005 : // => https://github.com/neondatabase/neon/issues/6065
635 6005 : slot_guard.file.replace(file);
636 6005 :
637 6005 : Ok(vfile)
638 6005 : }
639 :
640 : /// Async version of [`::utils::crashsafe::overwrite`].
641 : ///
642 : /// # NB:
643 : ///
644 : /// Doesn't actually use the [`VirtualFile`] file descriptor cache, but,
645 : /// it did at an earlier time.
646 : /// And it will use this module's [`io_engine`] in the near future, so, leaving it here.
647 28 : pub async fn crashsafe_overwrite<B: BoundedBuf<Buf = Buf> + Send, Buf: IoBuf + Send>(
648 28 : final_path: Utf8PathBuf,
649 28 : tmp_path: Utf8PathBuf,
650 28 : content: B,
651 28 : ) -> std::io::Result<()> {
652 28 : // TODO: use tokio_epoll_uring if configured as `io_engine`.
653 28 : // See https://github.com/neondatabase/neon/issues/6663
654 28 :
655 28 : tokio::task::spawn_blocking(move || {
656 28 : let slice_storage;
657 28 : let content_len = content.bytes_init();
658 28 : let content = if content.bytes_init() > 0 {
659 28 : slice_storage = Some(content.slice(0..content_len));
660 28 : slice_storage.as_deref().expect("just set it to Some()")
661 : } else {
662 0 : &[]
663 : };
664 28 : utils::crashsafe::overwrite(&final_path, &tmp_path, content)
665 28 : .maybe_fatal_err("crashsafe_overwrite")
666 28 : })
667 28 : .await
668 28 : .expect("blocking task is never aborted")
669 28 : }
670 :
671 : /// Call File::sync_all() on the underlying File.
672 2773 : pub async fn sync_all(&self) -> Result<(), Error> {
673 2773 : with_file!(self, StorageIoOperation::Fsync, |file_guard| {
674 2773 : let (_file_guard, res) = io_engine::get().sync_all(file_guard).await;
675 2773 : res.maybe_fatal_err("sync_all")
676 : })
677 2773 : }
678 :
679 : /// Call File::sync_data() on the underlying File.
680 0 : pub async fn sync_data(&self) -> Result<(), Error> {
681 0 : with_file!(self, StorageIoOperation::Fsync, |file_guard| {
682 0 : let (_file_guard, res) = io_engine::get().sync_data(file_guard).await;
683 0 : res.maybe_fatal_err("sync_data")
684 : })
685 0 : }
686 :
687 1770 : pub async fn metadata(&self) -> Result<Metadata, Error> {
688 1770 : with_file!(self, StorageIoOperation::Metadata, |file_guard| {
689 1770 : let (_file_guard, res) = io_engine::get().metadata(file_guard).await;
690 1770 : res
691 : })
692 1770 : }
693 :
694 : /// Helper function internal to `VirtualFile` that looks up the underlying File,
695 : /// opens it and evicts some other File if necessary. The passed parameter is
696 : /// assumed to be a function available for the physical `File`.
697 : ///
698 : /// We are doing it via a macro as Rust doesn't support async closures that
699 : /// take on parameters with lifetimes.
700 1617483 : async fn lock_file(&self) -> Result<FileGuard, Error> {
701 1617483 : let open_files = get_open_files();
702 :
703 186475 : let mut handle_guard = {
704 : // Read the cached slot handle, and see if the slot that it points to still
705 : // contains our File.
706 : //
707 : // We only need to hold the handle lock while we read the current handle. If
708 : // another thread closes the file and recycles the slot for a different file,
709 : // we will notice that the handle we read is no longer valid and retry.
710 1617483 : let mut handle = *self.handle.read().await;
711 : loop {
712 : // Check if the slot contains our File
713 : {
714 1712404 : let slot = &open_files.slots[handle.index];
715 1712404 : let slot_guard = slot.inner.read().await;
716 1712404 : if slot_guard.tag == handle.tag && slot_guard.file.is_some() {
717 : // Found a cached file descriptor.
718 1431008 : slot.recently_used.store(true, Ordering::Relaxed);
719 1431008 : return Ok(FileGuard { slot_guard });
720 281396 : }
721 : }
722 :
723 : // The slot didn't contain our File. We will have to open it ourselves,
724 : // but before that, grab a write lock on handle in the VirtualFile, so
725 : // that no other thread will try to concurrently open the same file.
726 281396 : let handle_guard = self.handle.write().await;
727 :
728 : // If another thread changed the handle while we were not holding the lock,
729 : // then the handle might now be valid again. Loop back to retry.
730 281396 : if *handle_guard != handle {
731 94921 : handle = *handle_guard;
732 94921 : continue;
733 186475 : }
734 186475 : break handle_guard;
735 : }
736 : };
737 :
738 : // We need to open the file ourselves. The handle in the VirtualFile is
739 : // now locked in write-mode. Find a free slot to put it in.
740 186475 : let (handle, mut slot_guard) = open_files.find_victim_slot().await;
741 :
742 : // Re-open the physical file.
743 : // NB: we use StorageIoOperation::OpenAferReplace for this to distinguish this
744 : // case from StorageIoOperation::Open. This helps with identifying thrashing
745 : // of the virtual file descriptor cache.
746 186475 : let file = observe_duration!(StorageIoOperation::OpenAfterReplace, {
747 186475 : self.open_options.open(self.path.as_std_path()).await?
748 : });
749 :
750 : // Store the File in the slot and update the handle in the VirtualFile
751 : // to point to it.
752 186475 : slot_guard.file.replace(file);
753 186475 :
754 186475 : *handle_guard = handle;
755 186475 :
756 186475 : Ok(FileGuard {
757 186475 : slot_guard: slot_guard.downgrade(),
758 186475 : })
759 1617483 : }
760 :
761 232 : pub fn remove(self) {
762 232 : let path = self.path.clone();
763 232 : drop(self);
764 232 : std::fs::remove_file(path).expect("failed to remove the virtual file");
765 232 : }
766 :
767 5554 : pub async fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error> {
768 5554 : match pos {
769 5544 : SeekFrom::Start(offset) => {
770 5544 : self.pos = offset;
771 5544 : }
772 4 : SeekFrom::End(offset) => {
773 4 : self.pos = with_file!(self, StorageIoOperation::Seek, |mut file_guard| file_guard
774 4 : .with_std_file_mut(|std_file| std_file.seek(SeekFrom::End(offset))))?
775 : }
776 6 : SeekFrom::Current(offset) => {
777 6 : let pos = self.pos as i128 + offset as i128;
778 6 : if pos < 0 {
779 2 : return Err(Error::new(
780 2 : ErrorKind::InvalidInput,
781 2 : "offset would be negative",
782 2 : ));
783 4 : }
784 4 : if pos > u64::MAX as i128 {
785 0 : return Err(Error::new(ErrorKind::InvalidInput, "offset overflow"));
786 4 : }
787 4 : self.pos = pos as u64;
788 : }
789 : }
790 5550 : Ok(self.pos)
791 5554 : }
792 :
793 : /// Read the file contents in range `offset..(offset + slice.bytes_total())` into `slice[0..slice.bytes_total()]`.
794 : ///
795 : /// The returned `Slice<Buf>` is equivalent to the input `slice`, i.e., it's the same view into the same buffer.
796 475973 : pub async fn read_exact_at<Buf>(
797 475973 : &self,
798 475973 : slice: Slice<Buf>,
799 475973 : offset: u64,
800 475973 : ctx: &RequestContext,
801 475973 : ) -> Result<Slice<Buf>, Error>
802 475973 : where
803 475973 : Buf: IoBufAlignedMut + Send,
804 475973 : {
805 475973 : let assert_we_return_original_bounds = if cfg!(debug_assertions) {
806 475973 : Some((slice.stable_ptr() as usize, slice.bytes_total()))
807 : } else {
808 0 : None
809 : };
810 :
811 475973 : let original_bounds = slice.bounds();
812 475973 : let (buf, res) =
813 475973 : read_exact_at_impl(slice, offset, |buf, offset| self.read_at(buf, offset, ctx)).await;
814 475973 : let res = res.map(|_| buf.slice(original_bounds));
815 :
816 475973 : if let Some(original_bounds) = assert_we_return_original_bounds {
817 475973 : if let Ok(slice) = &res {
818 475973 : let returned_bounds = (slice.stable_ptr() as usize, slice.bytes_total());
819 475973 : assert_eq!(original_bounds, returned_bounds);
820 0 : }
821 0 : }
822 :
823 475973 : res
824 475973 : }
825 :
826 : /// Like [`Self::read_exact_at`] but for [`PageWriteGuard`].
827 32163 : pub async fn read_exact_at_page(
828 32163 : &self,
829 32163 : page: PageWriteGuard<'static>,
830 32163 : offset: u64,
831 32163 : ctx: &RequestContext,
832 32163 : ) -> Result<PageWriteGuard<'static>, Error> {
833 32163 : let buf = PageWriteGuardBuf { page }.slice_full();
834 32163 : debug_assert_eq!(buf.bytes_total(), PAGE_SZ);
835 32163 : self.read_exact_at(buf, offset, ctx)
836 32163 : .await
837 32163 : .map(|slice| slice.into_inner().page)
838 32163 : }
839 :
840 : // Copied from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#219-235
841 6607 : pub async fn write_all_at<Buf: IoBuf + Send>(
842 6607 : &self,
843 6607 : buf: FullSlice<Buf>,
844 6607 : mut offset: u64,
845 6607 : ctx: &RequestContext,
846 6607 : ) -> (FullSlice<Buf>, Result<(), Error>) {
847 6607 : let buf = buf.into_raw_slice();
848 6607 : let bounds = buf.bounds();
849 6607 : let restore =
850 6607 : |buf: Slice<_>| FullSlice::must_new(Slice::from_buf_bounds(buf.into_inner(), bounds));
851 6607 : let mut buf = buf;
852 13214 : while !buf.is_empty() {
853 6607 : let (tmp, res) = self.write_at(FullSlice::must_new(buf), offset, ctx).await;
854 6607 : buf = tmp.into_raw_slice();
855 0 : match res {
856 : Ok(0) => {
857 0 : return (
858 0 : restore(buf),
859 0 : Err(Error::new(
860 0 : std::io::ErrorKind::WriteZero,
861 0 : "failed to write whole buffer",
862 0 : )),
863 0 : );
864 : }
865 6607 : Ok(n) => {
866 6607 : buf = buf.slice(n..);
867 6607 : offset += n as u64;
868 6607 : }
869 0 : Err(e) if e.kind() == std::io::ErrorKind::Interrupted => {}
870 0 : Err(e) => return (restore(buf), Err(e)),
871 : }
872 : }
873 6607 : (restore(buf), Ok(()))
874 6607 : }
875 :
876 : /// Writes `buf` to the file at the current offset.
877 : ///
878 : /// Panics if there is an uninitialized range in `buf`, as that is most likely a bug in the caller.
879 1129950 : pub async fn write_all<Buf: IoBuf + Send>(
880 1129950 : &mut self,
881 1129950 : buf: FullSlice<Buf>,
882 1129950 : ctx: &RequestContext,
883 1129950 : ) -> (FullSlice<Buf>, Result<usize, Error>) {
884 1129950 : let buf = buf.into_raw_slice();
885 1129950 : let bounds = buf.bounds();
886 1129950 : let restore =
887 1129950 : |buf: Slice<_>| FullSlice::must_new(Slice::from_buf_bounds(buf.into_inner(), bounds));
888 1129950 : let nbytes = buf.len();
889 1129950 : let mut buf = buf;
890 2259860 : while !buf.is_empty() {
891 1129912 : let (tmp, res) = self.write(FullSlice::must_new(buf), ctx).await;
892 1129912 : buf = tmp.into_raw_slice();
893 2 : match res {
894 : Ok(0) => {
895 0 : return (
896 0 : restore(buf),
897 0 : Err(Error::new(
898 0 : std::io::ErrorKind::WriteZero,
899 0 : "failed to write whole buffer",
900 0 : )),
901 0 : );
902 : }
903 1129910 : Ok(n) => {
904 1129910 : buf = buf.slice(n..);
905 1129910 : }
906 2 : Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => {}
907 2 : Err(e) => return (restore(buf), Err(e)),
908 : }
909 : }
910 1129948 : (restore(buf), Ok(nbytes))
911 1129950 : }
912 :
913 1129912 : async fn write<B: IoBuf + Send>(
914 1129912 : &mut self,
915 1129912 : buf: FullSlice<B>,
916 1129912 : ctx: &RequestContext,
917 1129912 : ) -> (FullSlice<B>, Result<usize, std::io::Error>) {
918 1129912 : let pos = self.pos;
919 1129912 : let (buf, res) = self.write_at(buf, pos, ctx).await;
920 1129912 : let n = match res {
921 1129910 : Ok(n) => n,
922 2 : Err(e) => return (buf, Err(e)),
923 : };
924 1129910 : self.pos += n as u64;
925 1129910 : (buf, Ok(n))
926 1129912 : }
927 :
928 476417 : pub(crate) async fn read_at<Buf>(
929 476417 : &self,
930 476417 : buf: tokio_epoll_uring::Slice<Buf>,
931 476417 : offset: u64,
932 476417 : _ctx: &RequestContext, /* TODO: use for metrics: https://github.com/neondatabase/neon/issues/6107 */
933 476417 : ) -> (tokio_epoll_uring::Slice<Buf>, Result<usize, Error>)
934 476417 : where
935 476417 : Buf: tokio_epoll_uring::IoBufMut + Send,
936 476417 : {
937 476417 : let file_guard = match self.lock_file().await {
938 476417 : Ok(file_guard) => file_guard,
939 0 : Err(e) => return (buf, Err(e)),
940 : };
941 :
942 476417 : observe_duration!(StorageIoOperation::Read, {
943 476417 : let ((_file_guard, buf), res) = io_engine::get().read_at(file_guard, offset, buf).await;
944 476417 : if let Ok(size) = res {
945 476415 : STORAGE_IO_SIZE
946 476415 : .with_label_values(&[
947 476415 : "read",
948 476415 : &self.tenant_id,
949 476415 : &self.shard_id,
950 476415 : &self.timeline_id,
951 476415 : ])
952 476415 : .add(size as i64);
953 476415 : }
954 476417 : (buf, res)
955 : })
956 476417 : }
957 :
958 : /// The function aborts the process if the error is fatal.
959 1136519 : async fn write_at<B: IoBuf + Send>(
960 1136519 : &self,
961 1136519 : buf: FullSlice<B>,
962 1136519 : offset: u64,
963 1136519 : _ctx: &RequestContext, /* TODO: use for metrics: https://github.com/neondatabase/neon/issues/6107 */
964 1136519 : ) -> (FullSlice<B>, Result<usize, Error>) {
965 1136519 : let (slice, result) = self.write_at_inner(buf, offset, _ctx).await;
966 1136519 : let result = result.maybe_fatal_err("write_at");
967 1136519 : (slice, result)
968 1136519 : }
969 :
970 1136519 : async fn write_at_inner<B: IoBuf + Send>(
971 1136519 : &self,
972 1136519 : buf: FullSlice<B>,
973 1136519 : offset: u64,
974 1136519 : _ctx: &RequestContext, /* TODO: use for metrics: https://github.com/neondatabase/neon/issues/6107 */
975 1136519 : ) -> (FullSlice<B>, Result<usize, Error>) {
976 1136519 : let file_guard = match self.lock_file().await {
977 1136519 : Ok(file_guard) => file_guard,
978 0 : Err(e) => return (buf, Err(e)),
979 : };
980 1136519 : observe_duration!(StorageIoOperation::Write, {
981 1136519 : let ((_file_guard, buf), result) =
982 1136519 : io_engine::get().write_at(file_guard, offset, buf).await;
983 1136519 : if let Ok(size) = result {
984 1136517 : STORAGE_IO_SIZE
985 1136517 : .with_label_values(&[
986 1136517 : "write",
987 1136517 : &self.tenant_id,
988 1136517 : &self.shard_id,
989 1136517 : &self.timeline_id,
990 1136517 : ])
991 1136517 : .add(size as i64);
992 1136517 : }
993 1136519 : (buf, result)
994 : })
995 1136519 : }
996 : }
997 :
998 : // Adapted from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#117-135
999 475981 : pub async fn read_exact_at_impl<Buf, F, Fut>(
1000 475981 : mut buf: tokio_epoll_uring::Slice<Buf>,
1001 475981 : mut offset: u64,
1002 475981 : mut read_at: F,
1003 475981 : ) -> (Buf, std::io::Result<()>)
1004 475981 : where
1005 475981 : Buf: IoBufMut + Send,
1006 475981 : F: FnMut(tokio_epoll_uring::Slice<Buf>, u64) -> Fut,
1007 475981 : Fut: std::future::Future<Output = (tokio_epoll_uring::Slice<Buf>, std::io::Result<usize>)>,
1008 475981 : {
1009 951964 : while buf.bytes_total() != 0 {
1010 : let res;
1011 475985 : (buf, res) = read_at(buf, offset).await;
1012 0 : match res {
1013 2 : Ok(0) => break,
1014 475983 : Ok(n) => {
1015 475983 : buf = buf.slice(n..);
1016 475983 : offset += n as u64;
1017 475983 : }
1018 0 : Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => {}
1019 0 : Err(e) => return (buf.into_inner(), Err(e)),
1020 : }
1021 : }
1022 : // NB: don't use `buf.is_empty()` here; it is from the
1023 : // `impl Deref for Slice { Target = [u8] }`; the &[u8]
1024 : // returned by it only covers the initialized portion of `buf`.
1025 : // Whereas we're interested in ensuring that we filled the entire
1026 : // buffer that the user passed in.
1027 475981 : if buf.bytes_total() != 0 {
1028 2 : (
1029 2 : buf.into_inner(),
1030 2 : Err(std::io::Error::new(
1031 2 : std::io::ErrorKind::UnexpectedEof,
1032 2 : "failed to fill whole buffer",
1033 2 : )),
1034 2 : )
1035 : } else {
1036 475979 : assert_eq!(buf.len(), buf.bytes_total());
1037 475979 : (buf.into_inner(), Ok(()))
1038 : }
1039 475981 : }
1040 :
1041 : #[cfg(test)]
1042 : mod test_read_exact_at_impl {
1043 :
1044 : use std::{collections::VecDeque, sync::Arc};
1045 :
1046 : use tokio_epoll_uring::{BoundedBuf, BoundedBufMut};
1047 :
1048 : use super::read_exact_at_impl;
1049 :
1050 : struct Expectation {
1051 : offset: u64,
1052 : bytes_total: usize,
1053 : result: std::io::Result<Vec<u8>>,
1054 : }
1055 : struct MockReadAt {
1056 : expectations: VecDeque<Expectation>,
1057 : }
1058 :
1059 : impl MockReadAt {
1060 12 : async fn read_at(
1061 12 : &mut self,
1062 12 : mut buf: tokio_epoll_uring::Slice<Vec<u8>>,
1063 12 : offset: u64,
1064 12 : ) -> (tokio_epoll_uring::Slice<Vec<u8>>, std::io::Result<usize>) {
1065 12 : let exp = self
1066 12 : .expectations
1067 12 : .pop_front()
1068 12 : .expect("read_at called but we have no expectations left");
1069 12 : assert_eq!(exp.offset, offset);
1070 12 : assert_eq!(exp.bytes_total, buf.bytes_total());
1071 12 : match exp.result {
1072 12 : Ok(bytes) => {
1073 12 : assert!(bytes.len() <= buf.bytes_total());
1074 12 : buf.put_slice(&bytes);
1075 12 : (buf, Ok(bytes.len()))
1076 : }
1077 0 : Err(e) => (buf, Err(e)),
1078 : }
1079 12 : }
1080 : }
1081 :
1082 : impl Drop for MockReadAt {
1083 8 : fn drop(&mut self) {
1084 8 : assert_eq!(self.expectations.len(), 0);
1085 8 : }
1086 : }
1087 :
1088 : #[tokio::test]
1089 2 : async fn test_basic() {
1090 2 : let buf = Vec::with_capacity(5).slice_full();
1091 2 : let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
1092 2 : expectations: VecDeque::from(vec![Expectation {
1093 2 : offset: 0,
1094 2 : bytes_total: 5,
1095 2 : result: Ok(vec![b'a', b'b', b'c', b'd', b'e']),
1096 2 : }]),
1097 2 : }));
1098 2 : let (buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
1099 2 : let mock_read_at = Arc::clone(&mock_read_at);
1100 2 : async move { mock_read_at.lock().await.read_at(buf, offset).await }
1101 2 : })
1102 2 : .await;
1103 2 : assert!(res.is_ok());
1104 2 : assert_eq!(buf, vec![b'a', b'b', b'c', b'd', b'e']);
1105 2 : }
1106 :
1107 : #[tokio::test]
1108 2 : async fn test_empty_buf_issues_no_syscall() {
1109 2 : let buf = Vec::new().slice_full();
1110 2 : let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
1111 2 : expectations: VecDeque::new(),
1112 2 : }));
1113 2 : let (_buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
1114 0 : let mock_read_at = Arc::clone(&mock_read_at);
1115 2 : async move { mock_read_at.lock().await.read_at(buf, offset).await }
1116 2 : })
1117 2 : .await;
1118 2 : assert!(res.is_ok());
1119 2 : }
1120 :
1121 : #[tokio::test]
1122 2 : async fn test_two_read_at_calls_needed_until_buf_filled() {
1123 2 : let buf = Vec::with_capacity(4).slice_full();
1124 2 : let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
1125 2 : expectations: VecDeque::from(vec![
1126 2 : Expectation {
1127 2 : offset: 0,
1128 2 : bytes_total: 4,
1129 2 : result: Ok(vec![b'a', b'b']),
1130 2 : },
1131 2 : Expectation {
1132 2 : offset: 2,
1133 2 : bytes_total: 2,
1134 2 : result: Ok(vec![b'c', b'd']),
1135 2 : },
1136 2 : ]),
1137 2 : }));
1138 4 : let (buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
1139 4 : let mock_read_at = Arc::clone(&mock_read_at);
1140 4 : async move { mock_read_at.lock().await.read_at(buf, offset).await }
1141 4 : })
1142 2 : .await;
1143 2 : assert!(res.is_ok());
1144 2 : assert_eq!(buf, vec![b'a', b'b', b'c', b'd']);
1145 2 : }
1146 :
1147 : #[tokio::test]
1148 2 : async fn test_eof_before_buffer_full() {
1149 2 : let buf = Vec::with_capacity(3).slice_full();
1150 2 : let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
1151 2 : expectations: VecDeque::from(vec![
1152 2 : Expectation {
1153 2 : offset: 0,
1154 2 : bytes_total: 3,
1155 2 : result: Ok(vec![b'a']),
1156 2 : },
1157 2 : Expectation {
1158 2 : offset: 1,
1159 2 : bytes_total: 2,
1160 2 : result: Ok(vec![b'b']),
1161 2 : },
1162 2 : Expectation {
1163 2 : offset: 2,
1164 2 : bytes_total: 1,
1165 2 : result: Ok(vec![]),
1166 2 : },
1167 2 : ]),
1168 2 : }));
1169 6 : let (_buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
1170 6 : let mock_read_at = Arc::clone(&mock_read_at);
1171 6 : async move { mock_read_at.lock().await.read_at(buf, offset).await }
1172 6 : })
1173 2 : .await;
1174 2 : let Err(err) = res else {
1175 2 : panic!("should return an error");
1176 2 : };
1177 2 : assert_eq!(err.kind(), std::io::ErrorKind::UnexpectedEof);
1178 2 : assert_eq!(format!("{err}"), "failed to fill whole buffer");
1179 2 : // buffer contents on error are unspecified
1180 2 : }
1181 : }
1182 :
1183 : struct FileGuard {
1184 : slot_guard: RwLockReadGuard<'static, SlotInner>,
1185 : }
1186 :
1187 : impl AsRef<OwnedFd> for FileGuard {
1188 1617483 : fn as_ref(&self) -> &OwnedFd {
1189 1617483 : // This unwrap is safe because we only create `FileGuard`s
1190 1617483 : // if we know that the file is Some.
1191 1617483 : self.slot_guard.file.as_ref().unwrap()
1192 1617483 : }
1193 : }
1194 :
1195 : impl FileGuard {
1196 : /// Soft deprecation: we'll move VirtualFile to async APIs and remove this function eventually.
1197 808857 : fn with_std_file<F, R>(&self, with: F) -> R
1198 808857 : where
1199 808857 : F: FnOnce(&File) -> R,
1200 808857 : {
1201 808857 : // SAFETY:
1202 808857 : // - lifetime of the fd: `file` doesn't outlive the OwnedFd stored in `self`.
1203 808857 : // - `&` usage below: `self` is `&`, hence Rust typesystem guarantees there are is no `&mut`
1204 808857 : let file = unsafe { File::from_raw_fd(self.as_ref().as_raw_fd()) };
1205 808857 : let res = with(&file);
1206 808857 : let _ = file.into_raw_fd();
1207 808857 : res
1208 808857 : }
1209 : /// Soft deprecation: we'll move VirtualFile to async APIs and remove this function eventually.
1210 4 : fn with_std_file_mut<F, R>(&mut self, with: F) -> R
1211 4 : where
1212 4 : F: FnOnce(&mut File) -> R,
1213 4 : {
1214 4 : // SAFETY:
1215 4 : // - lifetime of the fd: `file` doesn't outlive the OwnedFd stored in `self`.
1216 4 : // - &mut usage below: `self` is `&mut`, hence this call is the only task/thread that has control over the underlying fd
1217 4 : let mut file = unsafe { File::from_raw_fd(self.as_ref().as_raw_fd()) };
1218 4 : let res = with(&mut file);
1219 4 : let _ = file.into_raw_fd();
1220 4 : res
1221 4 : }
1222 : }
1223 :
1224 : impl tokio_epoll_uring::IoFd for FileGuard {
1225 808622 : unsafe fn as_fd(&self) -> RawFd {
1226 808622 : let owned_fd: &OwnedFd = self.as_ref();
1227 808622 : owned_fd.as_raw_fd()
1228 808622 : }
1229 : }
1230 :
1231 : #[cfg(test)]
1232 : impl VirtualFile {
1233 20916 : pub(crate) async fn read_blk(
1234 20916 : &self,
1235 20916 : blknum: u32,
1236 20916 : ctx: &RequestContext,
1237 20916 : ) -> Result<crate::tenant::block_io::BlockLease<'_>, std::io::Error> {
1238 20916 : self.inner.read_blk(blknum, ctx).await
1239 20916 : }
1240 :
1241 224 : async fn read_to_end(&mut self, buf: &mut Vec<u8>, ctx: &RequestContext) -> Result<(), Error> {
1242 224 : self.inner.read_to_end(buf, ctx).await
1243 224 : }
1244 : }
1245 :
1246 : #[cfg(test)]
1247 : impl VirtualFileInner {
1248 20916 : pub(crate) async fn read_blk(
1249 20916 : &self,
1250 20916 : blknum: u32,
1251 20916 : ctx: &RequestContext,
1252 20916 : ) -> Result<crate::tenant::block_io::BlockLease<'_>, std::io::Error> {
1253 : use crate::page_cache::PAGE_SZ;
1254 20916 : let slice = IoBufferMut::with_capacity(PAGE_SZ).slice_full();
1255 20916 : assert_eq!(slice.bytes_total(), PAGE_SZ);
1256 20916 : let slice = self
1257 20916 : .read_exact_at(slice, blknum as u64 * (PAGE_SZ as u64), ctx)
1258 20916 : .await?;
1259 20916 : Ok(crate::tenant::block_io::BlockLease::IoBufferMut(
1260 20916 : slice.into_inner(),
1261 20916 : ))
1262 20916 : }
1263 :
1264 224 : async fn read_to_end(&mut self, buf: &mut Vec<u8>, ctx: &RequestContext) -> Result<(), Error> {
1265 224 : let mut tmp = vec![0; 128];
1266 : loop {
1267 444 : let slice = tmp.slice(..128);
1268 444 : let (slice, res) = self.read_at(slice, self.pos, ctx).await;
1269 2 : match res {
1270 222 : Ok(0) => return Ok(()),
1271 220 : Ok(n) => {
1272 220 : self.pos += n as u64;
1273 220 : buf.extend_from_slice(&slice[..n]);
1274 220 : }
1275 2 : Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => {}
1276 2 : Err(e) => return Err(e),
1277 : }
1278 220 : tmp = slice.into_inner();
1279 : }
1280 224 : }
1281 : }
1282 :
1283 : impl Drop for VirtualFileInner {
1284 : /// If a VirtualFile is dropped, close the underlying file if it was open.
1285 5199 : fn drop(&mut self) {
1286 5199 : let handle = self.handle.get_mut();
1287 :
1288 5199 : fn clean_slot(slot: &Slot, mut slot_guard: RwLockWriteGuard<'_, SlotInner>, tag: u64) {
1289 5199 : if slot_guard.tag == tag {
1290 4614 : slot.recently_used.store(false, Ordering::Relaxed);
1291 : // there is also operation "close-by-replace" for closes done on eviction for
1292 : // comparison.
1293 4614 : if let Some(fd) = slot_guard.file.take() {
1294 4614 : STORAGE_IO_TIME_METRIC
1295 4614 : .get(StorageIoOperation::Close)
1296 4614 : .observe_closure_duration(|| drop(fd));
1297 4614 : }
1298 585 : }
1299 5199 : }
1300 :
1301 : // We don't have async drop so we cannot directly await the lock here.
1302 : // Instead, first do a best-effort attempt at closing the underlying
1303 : // file descriptor by using `try_write`, and if that fails, spawn
1304 : // a tokio task to do it asynchronously: we just want it to be
1305 : // cleaned up eventually.
1306 : // Most of the time, the `try_lock` should succeed though,
1307 : // as we have `&mut self` access. In other words, if the slot
1308 : // is still occupied by our file, there should be no access from
1309 : // other I/O operations; the only other possible place to lock
1310 : // the slot is the lock algorithm looking for free slots.
1311 5199 : let slot = &get_open_files().slots[handle.index];
1312 5199 : if let Ok(slot_guard) = slot.inner.try_write() {
1313 5199 : clean_slot(slot, slot_guard, handle.tag);
1314 5199 : } else {
1315 0 : let tag = handle.tag;
1316 0 : tokio::spawn(async move {
1317 0 : let slot_guard = slot.inner.write().await;
1318 0 : clean_slot(slot, slot_guard, tag);
1319 0 : });
1320 0 : };
1321 5199 : }
1322 : }
1323 :
1324 : impl OwnedAsyncWriter for VirtualFile {
1325 6603 : async fn write_all_at<Buf: IoBufAligned + Send>(
1326 6603 : &self,
1327 6603 : buf: FullSlice<Buf>,
1328 6603 : offset: u64,
1329 6603 : ctx: &RequestContext,
1330 6603 : ) -> std::io::Result<FullSlice<Buf>> {
1331 6603 : let (buf, res) = VirtualFile::write_all_at(self, buf, offset, ctx).await;
1332 6603 : res.map(|_| buf)
1333 6603 : }
1334 : }
1335 :
1336 : impl OpenFiles {
1337 206 : fn new(num_slots: usize) -> OpenFiles {
1338 206 : let mut slots = Box::new(Vec::with_capacity(num_slots));
1339 2060 : for _ in 0..num_slots {
1340 2060 : let slot = Slot {
1341 2060 : recently_used: AtomicBool::new(false),
1342 2060 : inner: RwLock::new(SlotInner { tag: 0, file: None }),
1343 2060 : };
1344 2060 : slots.push(slot);
1345 2060 : }
1346 :
1347 206 : OpenFiles {
1348 206 : next: AtomicUsize::new(0),
1349 206 : slots: Box::leak(slots),
1350 206 : }
1351 206 : }
1352 : }
1353 :
1354 : ///
1355 : /// Initialize the virtual file module. This must be called once at page
1356 : /// server startup.
1357 : ///
1358 : #[cfg(not(test))]
1359 0 : pub fn init(num_slots: usize, engine: IoEngineKind, mode: IoMode, sync_mode: SyncMode) {
1360 0 : if OPEN_FILES.set(OpenFiles::new(num_slots)).is_err() {
1361 0 : panic!("virtual_file::init called twice");
1362 0 : }
1363 0 : set_io_mode(mode);
1364 0 : io_engine::init(engine);
1365 0 : SYNC_MODE.store(sync_mode as u8, std::sync::atomic::Ordering::Relaxed);
1366 0 : crate::metrics::virtual_file_descriptor_cache::SIZE_MAX.set(num_slots as u64);
1367 0 : }
1368 :
1369 : const TEST_MAX_FILE_DESCRIPTORS: usize = 10;
1370 :
1371 : // Get a handle to the global slots array.
1372 1628687 : fn get_open_files() -> &'static OpenFiles {
1373 1628687 : //
1374 1628687 : // In unit tests, page server startup doesn't happen and no one calls
1375 1628687 : // virtual_file::init(). Initialize it here, with a small array.
1376 1628687 : //
1377 1628687 : // This applies to the virtual file tests below, but all other unit
1378 1628687 : // tests too, so the virtual file facility is always usable in
1379 1628687 : // unit tests.
1380 1628687 : //
1381 1628687 : if cfg!(test) {
1382 1628687 : OPEN_FILES.get_or_init(|| OpenFiles::new(TEST_MAX_FILE_DESCRIPTORS))
1383 : } else {
1384 0 : OPEN_FILES.get().expect("virtual_file::init not called yet")
1385 : }
1386 1628687 : }
1387 :
1388 : /// Gets the io buffer alignment.
1389 0 : pub(crate) const fn get_io_buffer_alignment() -> usize {
1390 0 : DEFAULT_IO_BUFFER_ALIGNMENT
1391 0 : }
1392 :
1393 : pub(crate) type IoBufferMut = AlignedBufferMut<ConstAlign<{ get_io_buffer_alignment() }>>;
1394 : pub(crate) type IoBuffer = AlignedBuffer<ConstAlign<{ get_io_buffer_alignment() }>>;
1395 : pub(crate) type IoPageSlice<'a> =
1396 : AlignedSlice<'a, PAGE_SZ, ConstAlign<{ get_io_buffer_alignment() }>>;
1397 :
1398 : static IO_MODE: AtomicU8 = AtomicU8::new(IoMode::preferred() as u8);
1399 :
1400 0 : pub(crate) fn set_io_mode(mode: IoMode) {
1401 0 : IO_MODE.store(mode as u8, std::sync::atomic::Ordering::Relaxed);
1402 0 : }
1403 :
1404 2508 : pub(crate) fn get_io_mode() -> IoMode {
1405 2508 : IoMode::try_from(IO_MODE.load(Ordering::Relaxed)).unwrap()
1406 2508 : }
1407 :
1408 : static SYNC_MODE: AtomicU8 = AtomicU8::new(SyncMode::Sync as u8);
1409 :
1410 : #[cfg(test)]
1411 : mod tests {
1412 : use crate::context::DownloadBehavior;
1413 : use crate::task_mgr::TaskKind;
1414 :
1415 : use super::*;
1416 : use owned_buffers_io::io_buf_ext::IoBufExt;
1417 : use owned_buffers_io::slice::SliceMutExt;
1418 : use rand::seq::SliceRandom;
1419 : use rand::thread_rng;
1420 : use rand::Rng;
1421 : use std::io::Write;
1422 : use std::os::unix::fs::FileExt;
1423 : use std::sync::Arc;
1424 :
1425 : enum MaybeVirtualFile {
1426 : VirtualFile(VirtualFile),
1427 : File(File),
1428 : }
1429 :
1430 : impl From<VirtualFile> for MaybeVirtualFile {
1431 6 : fn from(vf: VirtualFile) -> Self {
1432 6 : MaybeVirtualFile::VirtualFile(vf)
1433 6 : }
1434 : }
1435 :
1436 : impl MaybeVirtualFile {
1437 404 : async fn read_exact_at(
1438 404 : &self,
1439 404 : mut slice: tokio_epoll_uring::Slice<IoBufferMut>,
1440 404 : offset: u64,
1441 404 : ctx: &RequestContext,
1442 404 : ) -> Result<tokio_epoll_uring::Slice<IoBufferMut>, Error> {
1443 404 : match self {
1444 202 : MaybeVirtualFile::VirtualFile(file) => file.read_exact_at(slice, offset, ctx).await,
1445 202 : MaybeVirtualFile::File(file) => {
1446 202 : let rust_slice: &mut [u8] = slice.as_mut_rust_slice_full_zeroed();
1447 202 : file.read_exact_at(rust_slice, offset).map(|()| slice)
1448 : }
1449 : }
1450 404 : }
1451 8 : async fn write_all_at<Buf: IoBufAligned + Send>(
1452 8 : &self,
1453 8 : buf: FullSlice<Buf>,
1454 8 : offset: u64,
1455 8 : ctx: &RequestContext,
1456 8 : ) -> Result<(), Error> {
1457 8 : match self {
1458 4 : MaybeVirtualFile::VirtualFile(file) => {
1459 4 : let (_buf, res) = file.write_all_at(buf, offset, ctx).await;
1460 4 : res
1461 : }
1462 4 : MaybeVirtualFile::File(file) => file.write_all_at(&buf[..], offset),
1463 : }
1464 8 : }
1465 36 : async fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error> {
1466 36 : match self {
1467 18 : MaybeVirtualFile::VirtualFile(file) => file.seek(pos).await,
1468 18 : MaybeVirtualFile::File(file) => file.seek(pos),
1469 : }
1470 36 : }
1471 8 : async fn write_all<Buf: IoBuf + Send>(
1472 8 : &mut self,
1473 8 : buf: FullSlice<Buf>,
1474 8 : ctx: &RequestContext,
1475 8 : ) -> Result<(), Error> {
1476 8 : match self {
1477 4 : MaybeVirtualFile::VirtualFile(file) => {
1478 4 : let (_buf, res) = file.write_all(buf, ctx).await;
1479 4 : res.map(|_| ())
1480 : }
1481 4 : MaybeVirtualFile::File(file) => file.write_all(&buf[..]),
1482 : }
1483 8 : }
1484 :
1485 : // Helper function to slurp contents of a file, starting at the current position,
1486 : // into a string
1487 442 : async fn read_string(&mut self, ctx: &RequestContext) -> Result<String, Error> {
1488 : use std::io::Read;
1489 442 : let mut buf = String::new();
1490 442 : match self {
1491 224 : MaybeVirtualFile::VirtualFile(file) => {
1492 224 : let mut buf = Vec::new();
1493 224 : file.read_to_end(&mut buf, ctx).await?;
1494 222 : return Ok(String::from_utf8(buf).unwrap());
1495 : }
1496 218 : MaybeVirtualFile::File(file) => {
1497 218 : file.read_to_string(&mut buf)?;
1498 : }
1499 : }
1500 216 : Ok(buf)
1501 442 : }
1502 :
1503 : // Helper function to slurp a portion of a file into a string
1504 404 : async fn read_string_at(
1505 404 : &mut self,
1506 404 : pos: u64,
1507 404 : len: usize,
1508 404 : ctx: &RequestContext,
1509 404 : ) -> Result<String, Error> {
1510 404 : let slice = IoBufferMut::with_capacity(len).slice_full();
1511 404 : assert_eq!(slice.bytes_total(), len);
1512 404 : let slice = self.read_exact_at(slice, pos, ctx).await?;
1513 404 : let buf = slice.into_inner();
1514 404 : assert_eq!(buf.len(), len);
1515 :
1516 404 : Ok(String::from_utf8(buf.to_vec()).unwrap())
1517 404 : }
1518 : }
1519 :
1520 : #[tokio::test]
1521 2 : async fn test_virtual_files() -> anyhow::Result<()> {
1522 2 : // The real work is done in the test_files() helper function. This
1523 2 : // allows us to run the same set of tests against a native File, and
1524 2 : // VirtualFile. We trust the native Files and wouldn't need to test them,
1525 2 : // but this allows us to verify that the operations return the same
1526 2 : // results with VirtualFiles as with native Files. (Except that with
1527 2 : // native files, you will run out of file descriptors if the ulimit
1528 2 : // is low enough.)
1529 2 : struct A;
1530 2 :
1531 2 : impl Adapter for A {
1532 206 : async fn open(
1533 206 : path: Utf8PathBuf,
1534 206 : opts: OpenOptions,
1535 206 : ctx: &RequestContext,
1536 206 : ) -> Result<MaybeVirtualFile, anyhow::Error> {
1537 206 : let vf = VirtualFile::open_with_options(&path, &opts, ctx).await?;
1538 206 : Ok(MaybeVirtualFile::VirtualFile(vf))
1539 206 : }
1540 2 : }
1541 2 : test_files::<A>("virtual_files").await
1542 2 : }
1543 :
1544 : #[tokio::test]
1545 2 : async fn test_physical_files() -> anyhow::Result<()> {
1546 2 : struct B;
1547 2 :
1548 2 : impl Adapter for B {
1549 206 : async fn open(
1550 206 : path: Utf8PathBuf,
1551 206 : opts: OpenOptions,
1552 206 : _ctx: &RequestContext,
1553 206 : ) -> Result<MaybeVirtualFile, anyhow::Error> {
1554 2 : Ok(MaybeVirtualFile::File({
1555 206 : let owned_fd = opts.open(path.as_std_path()).await?;
1556 206 : File::from(owned_fd)
1557 2 : }))
1558 206 : }
1559 2 : }
1560 2 :
1561 2 : test_files::<B>("physical_files").await
1562 2 : }
1563 :
1564 : /// This is essentially a closure which returns a MaybeVirtualFile, but because rust edition
1565 : /// 2024 is not yet out with new lifetime capture or outlives rules, this is a async function
1566 : /// in trait which benefits from the new lifetime capture rules already.
1567 : trait Adapter {
1568 : async fn open(
1569 : path: Utf8PathBuf,
1570 : opts: OpenOptions,
1571 : ctx: &RequestContext,
1572 : ) -> Result<MaybeVirtualFile, anyhow::Error>;
1573 : }
1574 :
1575 4 : async fn test_files<A>(testname: &str) -> anyhow::Result<()>
1576 4 : where
1577 4 : A: Adapter,
1578 4 : {
1579 4 : let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
1580 4 : let testdir = crate::config::PageServerConf::test_repo_dir(testname);
1581 4 : std::fs::create_dir_all(&testdir)?;
1582 :
1583 4 : let path_a = testdir.join("file_a");
1584 4 : let mut file_a = A::open(
1585 4 : path_a.clone(),
1586 4 : OpenOptions::new()
1587 4 : .write(true)
1588 4 : .create(true)
1589 4 : .truncate(true)
1590 4 : .to_owned(),
1591 4 : &ctx,
1592 4 : )
1593 4 : .await?;
1594 :
1595 4 : file_a
1596 4 : .write_all(b"foobar".to_vec().slice_len(), &ctx)
1597 4 : .await?;
1598 :
1599 : // cannot read from a file opened in write-only mode
1600 4 : let _ = file_a.read_string(&ctx).await.unwrap_err();
1601 :
1602 : // Close the file and re-open for reading
1603 4 : let mut file_a = A::open(path_a, OpenOptions::new().read(true).to_owned(), &ctx).await?;
1604 :
1605 : // cannot write to a file opened in read-only mode
1606 4 : let _ = file_a
1607 4 : .write_all(b"bar".to_vec().slice_len(), &ctx)
1608 4 : .await
1609 4 : .unwrap_err();
1610 4 :
1611 4 : // Try simple read
1612 4 : assert_eq!("foobar", file_a.read_string(&ctx).await?);
1613 :
1614 : // It's positioned at the EOF now.
1615 4 : assert_eq!("", file_a.read_string(&ctx).await?);
1616 :
1617 : // Test seeks.
1618 4 : assert_eq!(file_a.seek(SeekFrom::Start(1)).await?, 1);
1619 4 : assert_eq!("oobar", file_a.read_string(&ctx).await?);
1620 :
1621 4 : assert_eq!(file_a.seek(SeekFrom::End(-2)).await?, 4);
1622 4 : assert_eq!("ar", file_a.read_string(&ctx).await?);
1623 :
1624 4 : assert_eq!(file_a.seek(SeekFrom::Start(1)).await?, 1);
1625 4 : assert_eq!(file_a.seek(SeekFrom::Current(2)).await?, 3);
1626 4 : assert_eq!("bar", file_a.read_string(&ctx).await?);
1627 :
1628 4 : assert_eq!(file_a.seek(SeekFrom::Current(-5)).await?, 1);
1629 4 : assert_eq!("oobar", file_a.read_string(&ctx).await?);
1630 :
1631 : // Test erroneous seeks to before byte 0
1632 4 : file_a.seek(SeekFrom::End(-7)).await.unwrap_err();
1633 4 : assert_eq!(file_a.seek(SeekFrom::Start(1)).await?, 1);
1634 4 : file_a.seek(SeekFrom::Current(-2)).await.unwrap_err();
1635 4 :
1636 4 : // the erroneous seek should have left the position unchanged
1637 4 : assert_eq!("oobar", file_a.read_string(&ctx).await?);
1638 :
1639 : // Create another test file, and try FileExt functions on it.
1640 4 : let path_b = testdir.join("file_b");
1641 4 : let mut file_b = A::open(
1642 4 : path_b.clone(),
1643 4 : OpenOptions::new()
1644 4 : .read(true)
1645 4 : .write(true)
1646 4 : .create(true)
1647 4 : .truncate(true)
1648 4 : .to_owned(),
1649 4 : &ctx,
1650 4 : )
1651 4 : .await?;
1652 4 : file_b
1653 4 : .write_all_at(IoBuffer::from(b"BAR").slice_len(), 3, &ctx)
1654 4 : .await?;
1655 4 : file_b
1656 4 : .write_all_at(IoBuffer::from(b"FOO").slice_len(), 0, &ctx)
1657 4 : .await?;
1658 :
1659 4 : assert_eq!(file_b.read_string_at(2, 3, &ctx).await?, "OBA");
1660 :
1661 : // Open a lot of files, enough to cause some evictions. (Or to be precise,
1662 : // open the same file many times. The effect is the same.)
1663 : //
1664 : // leave file_a positioned at offset 1 before we start
1665 4 : assert_eq!(file_a.seek(SeekFrom::Start(1)).await?, 1);
1666 :
1667 4 : let mut vfiles = Vec::new();
1668 404 : for _ in 0..100 {
1669 400 : let mut vfile = A::open(
1670 400 : path_b.clone(),
1671 400 : OpenOptions::new().read(true).to_owned(),
1672 400 : &ctx,
1673 400 : )
1674 400 : .await?;
1675 400 : assert_eq!("FOOBAR", vfile.read_string(&ctx).await?);
1676 400 : vfiles.push(vfile);
1677 : }
1678 :
1679 : // make sure we opened enough files to definitely cause evictions.
1680 4 : assert!(vfiles.len() > TEST_MAX_FILE_DESCRIPTORS * 2);
1681 :
1682 : // The underlying file descriptor for 'file_a' should be closed now. Try to read
1683 : // from it again. We left the file positioned at offset 1 above.
1684 4 : assert_eq!("oobar", file_a.read_string(&ctx).await?);
1685 :
1686 : // Check that all the other FDs still work too. Use them in random order for
1687 : // good measure.
1688 4 : vfiles.as_mut_slice().shuffle(&mut thread_rng());
1689 400 : for vfile in vfiles.iter_mut() {
1690 400 : assert_eq!("OOBAR", vfile.read_string_at(1, 5, &ctx).await?);
1691 : }
1692 :
1693 4 : Ok(())
1694 4 : }
1695 :
1696 : /// Test using VirtualFiles from many threads concurrently. This tests both using
1697 : /// a lot of VirtualFiles concurrently, causing evictions, and also using the same
1698 : /// VirtualFile from multiple threads concurrently.
1699 : #[tokio::test]
1700 2 : async fn test_vfile_concurrency() -> Result<(), Error> {
1701 2 : const SIZE: usize = 8 * 1024;
1702 2 : const VIRTUAL_FILES: usize = 100;
1703 2 : const THREADS: usize = 100;
1704 2 : const SAMPLE: [u8; SIZE] = [0xADu8; SIZE];
1705 2 :
1706 2 : let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
1707 2 : let testdir = crate::config::PageServerConf::test_repo_dir("vfile_concurrency");
1708 2 : std::fs::create_dir_all(&testdir)?;
1709 2 :
1710 2 : // Create a test file.
1711 2 : let test_file_path = testdir.join("concurrency_test_file");
1712 2 : {
1713 2 : let file = File::create(&test_file_path)?;
1714 2 : file.write_all_at(&SAMPLE, 0)?;
1715 2 : }
1716 2 :
1717 2 : // Open the file many times.
1718 2 : let mut files = Vec::new();
1719 202 : for _ in 0..VIRTUAL_FILES {
1720 200 : let f = VirtualFileInner::open_with_options(
1721 200 : &test_file_path,
1722 200 : OpenOptions::new().read(true),
1723 200 : &ctx,
1724 200 : )
1725 200 : .await?;
1726 200 : files.push(f);
1727 2 : }
1728 2 : let files = Arc::new(files);
1729 2 :
1730 2 : // Launch many threads, and use the virtual files concurrently in random order.
1731 2 : let rt = tokio::runtime::Builder::new_multi_thread()
1732 2 : .worker_threads(THREADS)
1733 2 : .thread_name("test_vfile_concurrency thread")
1734 2 : .build()
1735 2 : .unwrap();
1736 2 : let mut hdls = Vec::new();
1737 202 : for _threadno in 0..THREADS {
1738 200 : let files = files.clone();
1739 200 : let ctx = ctx.detached_child(TaskKind::UnitTest, DownloadBehavior::Error);
1740 200 : let hdl = rt.spawn(async move {
1741 200 : let mut buf = IoBufferMut::with_capacity_zeroed(SIZE);
1742 200 : let mut rng = rand::rngs::OsRng;
1743 200000 : for _ in 1..1000 {
1744 199800 : let f = &files[rng.gen_range(0..files.len())];
1745 199800 : buf = f
1746 199800 : .read_exact_at(buf.slice_full(), 0, &ctx)
1747 199800 : .await
1748 199800 : .unwrap()
1749 199800 : .into_inner();
1750 199800 : assert!(buf[..] == SAMPLE);
1751 2 : }
1752 200 : });
1753 200 : hdls.push(hdl);
1754 200 : }
1755 202 : for hdl in hdls {
1756 200 : hdl.await?;
1757 2 : }
1758 2 : std::mem::forget(rt);
1759 2 :
1760 2 : Ok(())
1761 2 : }
1762 :
1763 : #[tokio::test]
1764 2 : async fn test_atomic_overwrite_basic() {
1765 2 : let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
1766 2 : let testdir = crate::config::PageServerConf::test_repo_dir("test_atomic_overwrite_basic");
1767 2 : std::fs::create_dir_all(&testdir).unwrap();
1768 2 :
1769 2 : let path = testdir.join("myfile");
1770 2 : let tmp_path = testdir.join("myfile.tmp");
1771 2 :
1772 2 : VirtualFileInner::crashsafe_overwrite(path.clone(), tmp_path.clone(), b"foo".to_vec())
1773 2 : .await
1774 2 : .unwrap();
1775 2 : let mut file = MaybeVirtualFile::from(VirtualFile::open(&path, &ctx).await.unwrap());
1776 2 : let post = file.read_string(&ctx).await.unwrap();
1777 2 : assert_eq!(post, "foo");
1778 2 : assert!(!tmp_path.exists());
1779 2 : drop(file);
1780 2 :
1781 2 : VirtualFileInner::crashsafe_overwrite(path.clone(), tmp_path.clone(), b"bar".to_vec())
1782 2 : .await
1783 2 : .unwrap();
1784 2 : let mut file = MaybeVirtualFile::from(VirtualFile::open(&path, &ctx).await.unwrap());
1785 2 : let post = file.read_string(&ctx).await.unwrap();
1786 2 : assert_eq!(post, "bar");
1787 2 : assert!(!tmp_path.exists());
1788 2 : drop(file);
1789 2 : }
1790 :
1791 : #[tokio::test]
1792 2 : async fn test_atomic_overwrite_preexisting_tmp() {
1793 2 : let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
1794 2 : let testdir =
1795 2 : crate::config::PageServerConf::test_repo_dir("test_atomic_overwrite_preexisting_tmp");
1796 2 : std::fs::create_dir_all(&testdir).unwrap();
1797 2 :
1798 2 : let path = testdir.join("myfile");
1799 2 : let tmp_path = testdir.join("myfile.tmp");
1800 2 :
1801 2 : std::fs::write(&tmp_path, "some preexisting junk that should be removed").unwrap();
1802 2 : assert!(tmp_path.exists());
1803 2 :
1804 2 : VirtualFileInner::crashsafe_overwrite(path.clone(), tmp_path.clone(), b"foo".to_vec())
1805 2 : .await
1806 2 : .unwrap();
1807 2 :
1808 2 : let mut file = MaybeVirtualFile::from(VirtualFile::open(&path, &ctx).await.unwrap());
1809 2 : let post = file.read_string(&ctx).await.unwrap();
1810 2 : assert_eq!(post, "foo");
1811 2 : assert!(!tmp_path.exists());
1812 2 : drop(file);
1813 2 : }
1814 : }
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