├── .gitignore ├── README.md ├── Cargo.toml ├── src └── lib.rs └── COPYING /.gitignore: -------------------------------------------------------------------------------- 1 | /target 2 | **/*.rs.bk 3 | **/*~ 4 | Cargo.lock 5 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # io-uring 2 | 3 | Wrapper providing a safe and simple way to access liburing-sys features. 4 | 5 | ## Usage 6 | 7 | Add this to your `Cargo.toml`: 8 | 9 | ```toml 10 | [dependencies] 11 | io-uring = "0.2" 12 | ``` 13 | 14 | # License 15 | 16 | Rand is distributed under the terms of the LGPL-2.1 license. 17 | 18 | See [COPYING](COPYING) for details. 19 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "io-uring" 3 | version = "0.2.0" 4 | authors = ["Sergio Lopez "] 5 | description = "Wrapper providing a safe and simple way to access liburing-sys features." 6 | edition = "2018" 7 | license = "LGPL-2.1-only" 8 | readme = "README.md" 9 | repository = "https://github.com/slp/io-uring" 10 | categories = ["asynchronous", "filesystem"] 11 | keywords = ["io", "async", "non-blocking", "uring"] 12 | documentation = "https://docs.rs/io-uring" 13 | 14 | [dependencies] 15 | libc = "0.2.55" 16 | liburing-sys = "0.1.2" 17 | 18 | [dev-dependencies] 19 | tempfile = "3.0.8" 20 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | // Copyright 2019 Red Hat, Inc. All Rights Reserved. 2 | // SPDX-License-Identifier: LGPL-2.1-only 3 | 4 | //! This crate provides a wrapper around liburing-sys providing a safe 5 | //! and simple way for creating a io_uring instance, registering an eventfd 6 | //! file descriptor for receiving completion notifications, submitting read 7 | //! and write requests, and checking for completions. 8 | //! 9 | //! # Usage 10 | //! 11 | //! ## Requirements 12 | //! 13 | //! This crate requires a kernel with io_uring support. This means 5.1 or 14 | //! higher. Support for registering an eventfd for receiving completion 15 | //! notifications requires 5.2 or higher. 16 | //! 17 | //! ## Unaligned buffers 18 | //! 19 | //! Under certain circumstances, io_uring may require the buffer holding the 20 | //! data for a write operation, or used to store the data for a read request, 21 | //! to be page-aligned. 22 | //! 23 | //! This crate checks the buffer alignment, and it either passes it directly 24 | //! to the kernel (if page aligned), or uses a temporary self-allocated buffer 25 | //! for the operation (if not page aligned), copying in/out the data between 26 | //! both buffers as required. 27 | //! 28 | //! This behavior allows users of this crate to avoid worrying about buffer 29 | //! alignment themselves, but this comes with a cost (one additional copy plus 30 | //! the cost of allocating and freeing the temporary buffer). Users desiring 31 | //! to obtain the best possible performance need to make sure their buffers 32 | //! are aligned before using them to submit read/write requests to UringQueue. 33 | //! 34 | //! ## Example 35 | //! 36 | //! ``` 37 | //! use io_uring::{Error, UringQueue}; 38 | //! use std::fs::File; 39 | //! use std::io; 40 | //! use std::os::unix::io::AsRawFd; 41 | //! 42 | //! fn read_exact(file: File, buf: &mut [u8], offset: i64, wait: bool) -> Result<(), Error> { 43 | //! let mut queue = UringQueue::new(128)?; 44 | //! let cookie: u64 = 1234; 45 | //! 46 | //! queue.prepare_read(file.as_raw_fd(), buf, offset, cookie)?; 47 | //! queue.submit_requests()?; 48 | //! match queue.get_completion(wait)? { 49 | //! Some(c) => { 50 | //! assert!(c == cookie); 51 | //! println!("Successfully read from file: buf={:?}", buf); 52 | //! Ok(()) 53 | //! } 54 | //! None => { 55 | //! assert!(!wait); 56 | //! Err(Error::IOError(io::Error::new( 57 | //! io::ErrorKind::WouldBlock, 58 | //! "completion queue was empty and wait == false", 59 | //! ))) 60 | //! } 61 | //! } 62 | //! } 63 | //!``` 64 | 65 | #![deny(missing_docs)] 66 | 67 | use core::cell::Cell; 68 | use std::io; 69 | use std::mem; 70 | use std::os::unix::io::RawFd; 71 | 72 | use libc; 73 | use liburing_sys::{ 74 | io_uring, io_uring_cqe, io_uring_cqe_seen, io_uring_get_sqe, io_uring_peek_cqe, 75 | io_uring_prep_readv, io_uring_prep_writev, io_uring_queue_exit, io_uring_queue_init, 76 | io_uring_register, io_uring_submit, io_uring_wait_cqe, 77 | }; 78 | 79 | /// Register an eventfd in the uring for completion notifications. 80 | pub const IORING_REGISTER_EVENTFD: u32 = 4; 81 | /// Unregister a previously registered eventfd. 82 | pub const IORING_UNREGISTER_EVENTFD: u32 = 5; 83 | 84 | #[derive(PartialEq)] 85 | enum RequestType { 86 | Read, 87 | Write, 88 | } 89 | 90 | #[repr(C)] 91 | struct UringRequest { 92 | iov: libc::iovec, 93 | fd: RawFd, 94 | offset: i64, 95 | client_iov: libc::iovec, 96 | client_cookie: u64, 97 | self_allocated: bool, 98 | request_type: RequestType, 99 | } 100 | 101 | /// Errors from UringQueue operations. 102 | #[derive(Debug)] 103 | pub enum Error { 104 | /// Can't initialize the underlying io_ring queue. 105 | CantInitializeQueue(io::Error), 106 | /// Can't register a EventFd with the io_ring queue. 107 | CantRegisterEventFd(io::Error), 108 | /// Can't allocate a temporary aligned buffer for the request. 109 | CantAllocateAlignedBuffer(io::Error), 110 | /// Can't submit the request to the io_ring queue. 111 | CantSubmitRequest(io::Error), 112 | /// Can't check the io_ring completion queue. 113 | CantCheckCompletionQueue(io::Error), 114 | /// The request failed to complete. 115 | IOError(io::Error), 116 | } 117 | 118 | /// UringQueue provides safe access to io_uring features. 119 | pub struct UringQueue { 120 | ring: io_uring, 121 | page_size: usize, 122 | } 123 | 124 | impl UringQueue { 125 | /// Create a new UringQueue with a fixed queue depth. 126 | pub fn new(queue_depth: u32) -> Result { 127 | let mut ring: io_uring = unsafe { mem::uninitialized() }; 128 | let ret = unsafe { io_uring_queue_init(queue_depth, &mut ring, 0) }; 129 | 130 | let page_size = unsafe { libc::sysconf(libc::_SC_PAGESIZE) as usize }; 131 | 132 | if ret < 0 { 133 | Err(Error::CantInitializeQueue(io::Error::from_raw_os_error( 134 | ret, 135 | ))) 136 | } else { 137 | Ok(UringQueue { ring, page_size }) 138 | } 139 | } 140 | 141 | /// Register an eventfd with the underlying io_uring to be notified when 142 | /// there's a pending completion in the queue. 143 | pub fn register_eventfd(&mut self, efd: RawFd) -> Result<(), Error> { 144 | let ret = unsafe { 145 | io_uring_register( 146 | self.ring.ring_fd, 147 | IORING_REGISTER_EVENTFD, 148 | Cell::new(efd).as_ptr() as *mut i32 as *mut core::ffi::c_void, 149 | 1, 150 | ) 151 | }; 152 | 153 | if ret < 0 { 154 | Err(Error::CantRegisterEventFd(io::Error::from_raw_os_error( 155 | ret, 156 | ))) 157 | } else { 158 | Ok(()) 159 | } 160 | } 161 | 162 | unsafe fn prepare_request( 163 | &self, 164 | fd: RawFd, 165 | buf_ptr: usize, 166 | buf_len: usize, 167 | offset: i64, 168 | cookie: u64, 169 | request_type: RequestType, 170 | ) -> Result<*mut UringRequest, Error> { 171 | let req_ptr = libc::malloc(mem::size_of::()); 172 | let mut req = req_ptr as *mut UringRequest; 173 | 174 | if buf_ptr % self.page_size == 0 { 175 | // Our caller is making things easy by providing us an aligned buffer. 176 | (*req).iov.iov_base = buf_ptr as *mut core::ffi::c_void; 177 | (*req).iov.iov_len = buf_len; 178 | (*req).self_allocated = false; 179 | } else { 180 | // Caller gave us an unaligned buffer, so we need to allocate one ourselves. 181 | let mut aligned_buf = mem::uninitialized(); 182 | let ret = libc::posix_memalign(&mut aligned_buf, self.page_size, buf_len); 183 | if ret != 0 { 184 | return Err(Error::CantAllocateAlignedBuffer( 185 | io::Error::from_raw_os_error(ret), 186 | )); 187 | } 188 | 189 | if request_type == RequestType::Write { 190 | libc::memcpy(aligned_buf, buf_ptr as *mut core::ffi::c_void, buf_len); 191 | } 192 | 193 | (*req).client_iov.iov_base = buf_ptr as *mut core::ffi::c_void; 194 | (*req).client_iov.iov_len = buf_len; 195 | (*req).iov.iov_base = aligned_buf; 196 | (*req).iov.iov_len = buf_len; 197 | (*req).fd = fd; 198 | (*req).offset = offset; 199 | (*req).self_allocated = true; 200 | } 201 | 202 | (*req).client_cookie = cookie; 203 | (*req).request_type = request_type; 204 | Ok(req) 205 | } 206 | 207 | /// Prepare and queue a request for reading from `fd`, starting at `offset`, and 208 | /// storing the result in `buf`. `cookie` is an arbitrary u64 value that can be 209 | /// used to keep track of the request. 210 | pub fn prepare_read( 211 | &mut self, 212 | fd: RawFd, 213 | buf: &mut [u8], 214 | offset: i64, 215 | cookie: u64, 216 | ) -> Result<(), Error> { 217 | let req = unsafe { 218 | self.prepare_request( 219 | fd, 220 | buf.as_ptr() as usize, 221 | buf.len(), 222 | offset, 223 | cookie, 224 | RequestType::Read, 225 | )? 226 | }; 227 | 228 | let sqe = unsafe { io_uring_get_sqe(&mut self.ring) }; 229 | if sqe.is_null() { 230 | panic!("can't get sqe"); 231 | } 232 | 233 | unsafe { io_uring_prep_readv(sqe, fd, &mut (*req).iov, 1, offset) }; 234 | unsafe { (*sqe).user_data = req as u64 }; 235 | 236 | Ok(()) 237 | } 238 | 239 | /// Prepare and queue a request for writing the contents of `buf` to `fd`, 240 | /// starting at `offset`. `cookie` is an arbitrary u64 value that can be 241 | /// used to keep track of the request. 242 | pub fn prepare_write( 243 | &mut self, 244 | fd: RawFd, 245 | buf: &[u8], 246 | offset: i64, 247 | cookie: u64, 248 | ) -> Result<(), Error> { 249 | let req = unsafe { 250 | self.prepare_request( 251 | fd, 252 | buf.as_ptr() as usize, 253 | buf.len(), 254 | offset, 255 | cookie, 256 | RequestType::Write, 257 | )? 258 | }; 259 | 260 | let sqe = unsafe { io_uring_get_sqe(&mut self.ring) }; 261 | if sqe.is_null() { 262 | panic!("can't get sqe"); 263 | } 264 | 265 | unsafe { io_uring_prep_writev(sqe, fd, &mut (*req).iov, 1, offset) }; 266 | unsafe { (*sqe).user_data = req as u64 }; 267 | 268 | Ok(()) 269 | } 270 | 271 | /// Notify the kernel that there are pending requests in the queue. 272 | pub fn submit_requests(&mut self) -> Result<(), Error> { 273 | let ret = unsafe { io_uring_submit(&mut self.ring) }; 274 | if ret < 0 { 275 | return Err(Error::CantSubmitRequest(io::Error::from_raw_os_error(ret))); 276 | } 277 | 278 | Ok(()) 279 | } 280 | 281 | /// Check the completion queue and, if there's completion available to be 282 | /// retrieved, process it and return the u64 value specified as `cookie` 283 | /// in the request. 284 | /// 285 | /// If there are no completions available in the queue and `wait` is 286 | /// `true`, keep waiting until there's a completion available, otherwise 287 | /// return `None`. 288 | pub fn get_completion(&mut self, wait: bool) -> Result, Error> { 289 | let mut cqe: *mut io_uring_cqe = unsafe { std::mem::zeroed() }; 290 | 291 | let ret = if wait { 292 | unsafe { io_uring_wait_cqe(&mut self.ring, &mut cqe) } 293 | } else { 294 | unsafe { io_uring_peek_cqe(&mut self.ring, &mut cqe) } 295 | }; 296 | 297 | if ret < 0 { 298 | return Err(Error::CantCheckCompletionQueue( 299 | io::Error::from_raw_os_error(ret), 300 | )); 301 | } 302 | if cqe.is_null() { 303 | return Ok(None); 304 | } 305 | 306 | let mut req = unsafe { &mut *((*cqe).user_data as *mut UringRequest) }; 307 | 308 | unsafe { 309 | if (*cqe).res < 0 { 310 | return Err(Error::IOError(io::Error::from_raw_os_error((*cqe).res))); 311 | } else if ((*cqe).res as usize) < req.iov.iov_len { 312 | // We've got a partial read/write. Adjust base and len, and queue again. 313 | req.iov.iov_base = 314 | ((req.iov.iov_base as usize) + (*cqe).res as usize) as *mut core::ffi::c_void; 315 | req.iov.iov_len -= (*cqe).res as usize; 316 | 317 | let sqe = io_uring_get_sqe(&mut self.ring); 318 | if sqe.is_null() { 319 | panic!("can't get sqe"); 320 | } 321 | 322 | match req.request_type { 323 | RequestType::Read => { 324 | io_uring_prep_readv(sqe, req.fd, &mut req.iov, 1, req.offset) 325 | } 326 | RequestType::Write => { 327 | io_uring_prep_writev(sqe, req.fd, &mut req.iov, 1, req.offset) 328 | } 329 | }; 330 | 331 | (*sqe).user_data = req as *const _ as u64; 332 | 333 | if !wait { 334 | return Ok(None); 335 | } else { 336 | return self.get_completion(wait); 337 | } 338 | } 339 | } 340 | 341 | if req.self_allocated { 342 | if req.request_type == RequestType::Read { 343 | unsafe { 344 | libc::memcpy( 345 | req.client_iov.iov_base, 346 | req.iov.iov_base, 347 | req.client_iov.iov_len, 348 | ) 349 | }; 350 | } 351 | 352 | unsafe { libc::free(req.iov.iov_base) }; 353 | } 354 | unsafe { libc::free(req as *const _ as *mut core::ffi::c_void) }; 355 | 356 | unsafe { io_uring_cqe_seen(&mut self.ring, cqe) }; 357 | Ok(Some(req.client_cookie)) 358 | } 359 | } 360 | 361 | impl Drop for UringQueue { 362 | fn drop(&mut self) { 363 | unsafe { io_uring_queue_exit(&mut self.ring) }; 364 | } 365 | } 366 | 367 | #[cfg(test)] 368 | mod tests { 369 | use crate::{Error, UringQueue}; 370 | use std::fs::File; 371 | use std::io::Write; 372 | use std::os::unix::io::AsRawFd; 373 | use tempfile::tempfile; 374 | 375 | fn prepare_test_file() -> Result { 376 | let mut file = tempfile().unwrap(); 377 | writeln!(file, "Test file").unwrap(); 378 | Ok(file) 379 | } 380 | 381 | #[test] 382 | fn create_queue() -> Result<(), Error> { 383 | let _queue = UringQueue::new(128)?; 384 | Ok(()) 385 | } 386 | 387 | #[test] 388 | fn submit_read() -> Result<(), Error> { 389 | let mut queue = UringQueue::new(128)?; 390 | let mut buf: [u8; 1] = [0u8]; 391 | let file = prepare_test_file()?; 392 | 393 | queue.prepare_read(file.as_raw_fd(), &mut buf[..], 0, 0)?; 394 | queue.submit_requests()?; 395 | Ok(()) 396 | } 397 | 398 | #[test] 399 | fn submit_write() -> Result<(), Error> { 400 | let mut queue = UringQueue::new(128)?; 401 | let buf: [u8; 1] = [0u8]; 402 | let file = prepare_test_file()?; 403 | 404 | queue.prepare_write(file.as_raw_fd(), &buf[..], 0, 0)?; 405 | queue.submit_requests()?; 406 | Ok(()) 407 | } 408 | 409 | #[test] 410 | fn submit_read_and_wait_for_completion() -> Result<(), Error> { 411 | let cookie: u64 = 1234; 412 | let mut queue = UringQueue::new(128)?; 413 | let mut buf: [u8; 1] = [0u8]; 414 | let file = prepare_test_file()?; 415 | 416 | queue.prepare_read(file.as_raw_fd(), &mut buf[..], 0, cookie)?; 417 | queue.submit_requests()?; 418 | let completion_cookie_opt = queue.get_completion(true)?; 419 | assert!(completion_cookie_opt.is_some()); 420 | let completion_cookie = completion_cookie_opt.unwrap(); 421 | 422 | assert!( 423 | completion_cookie == cookie, 424 | "completion_cookie={} cookie={}", 425 | completion_cookie, 426 | cookie 427 | ); 428 | Ok(()) 429 | } 430 | 431 | #[test] 432 | fn submit_read_and_peek_for_completion() -> Result<(), Error> { 433 | let cookie: u64 = 1234; 434 | let mut queue = UringQueue::new(128)?; 435 | let mut buf: [u8; 1] = [0u8]; 436 | let file = prepare_test_file()?; 437 | 438 | queue.prepare_read(file.as_raw_fd(), &mut buf[..], 0, cookie)?; 439 | queue.submit_requests()?; 440 | let completion_cookie_opt = queue.get_completion(true)?; 441 | assert!(completion_cookie_opt.is_some()); 442 | let completion_cookie = completion_cookie_opt.unwrap(); 443 | let completion_cookie_opt = queue.get_completion(false)?; 444 | assert!(completion_cookie_opt.is_none()); 445 | 446 | assert!( 447 | completion_cookie == cookie, 448 | "completion_cookie={} cookie={}", 449 | completion_cookie, 450 | cookie 451 | ); 452 | Ok(()) 453 | } 454 | 455 | #[test] 456 | fn submit_write_and_check_contents() -> Result<(), Error> { 457 | let wcookie: u64 = 1234; 458 | let rcookie: u64 = 4321; 459 | let mut queue = UringQueue::new(128)?; 460 | let test_str = "write test"; 461 | let mut buf: Vec = vec![]; 462 | 463 | let file = prepare_test_file()?; 464 | 465 | queue.prepare_write(file.as_raw_fd(), &test_str.as_bytes(), 0, wcookie)?; 466 | queue.submit_requests()?; 467 | let completion_cookie_opt = queue.get_completion(true)?; 468 | assert!(completion_cookie_opt.is_some()); 469 | let completion_cookie = completion_cookie_opt.unwrap(); 470 | assert!( 471 | completion_cookie == wcookie, 472 | "completion_cookie={} cookie={}", 473 | completion_cookie, 474 | wcookie 475 | ); 476 | 477 | buf.resize_with(test_str.as_bytes().len(), Default::default); 478 | queue.prepare_read(file.as_raw_fd(), &mut buf[..], 0, rcookie)?; 479 | queue.submit_requests()?; 480 | let completion_cookie_opt = queue.get_completion(true)?; 481 | assert!(completion_cookie_opt.is_some()); 482 | let completion_cookie = completion_cookie_opt.unwrap(); 483 | assert!( 484 | completion_cookie == rcookie, 485 | "completion_cookie={} cookie={}", 486 | completion_cookie, 487 | rcookie 488 | ); 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