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//! Simple and modular write-ahead-logging implementation.
//!
//! # Examples
//!
//! ```
//! use growthring::{WALStoreAIO, wal::WALLoader};
//! use futures::executor::block_on;
//! let mut loader = WALLoader::new();
//! loader.file_nbit(9).block_nbit(8);
//!
//!
//! // Start with empty WAL (truncate = true).
//! let store = WALStoreAIO::new("./walfiles", true, None, None).unwrap();
//! let mut wal = block_on(loader.load(store, |_, _| {Ok(())}, 0)).unwrap();
//! // Write a vector of records to WAL.
//! for f in wal.grow(vec!["record1(foo)", "record2(bar)", "record3(foobar)"]).into_iter() {
//! let ring_id = block_on(f).unwrap().1;
//! println!("WAL recorded record to {:?}", ring_id);
//! }
//!
//!
//! // Load from WAL (truncate = false).
//! let store = WALStoreAIO::new("./walfiles", false, None, None).unwrap();
//! let mut wal = block_on(loader.load(store, |payload, ringid| {
//! // redo the operations in your application
//! println!("recover(payload={}, ringid={:?})",
//! std::str::from_utf8(&payload).unwrap(),
//! ringid);
//! Ok(())
//! }, 0)).unwrap();
//! // We saw some log playback, even there is no failure.
//! // Let's try to grow the WAL to create many files.
//! let ring_ids = wal.grow((1..100).into_iter().map(|i| "a".repeat(i)).collect::<Vec<_>>())
//! .into_iter().map(|f| block_on(f).unwrap().1).collect::<Vec<_>>();
//! // Then assume all these records are not longer needed. We can tell WALWriter by the `peel`
//! // method.
//! block_on(wal.peel(ring_ids, 0)).unwrap();
//! // There will only be one remaining file in ./walfiles.
//!
//! let store = WALStoreAIO::new("./walfiles", false, None, None).unwrap();
//! let wal = block_on(loader.load(store, |payload, _| {
//! println!("payload.len() = {}", payload.len());
//! Ok(())
//! }, 0)).unwrap();
//! // After each recovery, the ./walfiles is empty.
//! ```
#[macro_use] extern crate scan_fmt;
pub mod wal;
use aiofut::{AIOBuilder, AIOManager};
use async_trait::async_trait;
use libc::off_t;
use nix::fcntl::{fallocate, open, openat, FallocateFlags, OFlag};
use nix::sys::stat::Mode;
use nix::unistd::{ftruncate, mkdir, unlinkat, UnlinkatFlags};
use std::os::fd::{AsFd, AsRawFd, BorrowedFd, FromRawFd, OwnedFd};
use std::sync::Arc;
use wal::{WALBytes, WALFile, WALPos, WALStore};
pub struct WALFileAIO {
fd: OwnedFd,
aiomgr: Arc<AIOManager>,
}
impl WALFileAIO {
pub fn new(
rootfd: BorrowedFd, filename: &str, aiomgr: Arc<AIOManager>,
) -> Result<Self, ()> {
openat(
rootfd.as_raw_fd(),
filename,
OFlag::O_CREAT | OFlag::O_RDWR,
Mode::S_IRUSR | Mode::S_IWUSR,
)
.and_then(|fd| {
Ok(WALFileAIO {
fd: unsafe { OwnedFd::from_raw_fd(fd) },
aiomgr,
})
})
.or_else(|_| Err(()))
}
}
#[async_trait(?Send)]
impl WALFile for WALFileAIO {
async fn allocate(&self, offset: WALPos, length: usize) -> Result<(), ()> {
// TODO: is there any async version of fallocate?
fallocate(
self.fd.as_raw_fd(),
FallocateFlags::FALLOC_FL_ZERO_RANGE,
offset as off_t,
length as off_t,
)
.and_then(|_| Ok(()))
.or_else(|_| Err(()))
}
fn truncate(&self, length: usize) -> Result<(), ()> {
ftruncate(&self.fd, length as off_t).or_else(|_| Err(()))
}
async fn write(&self, offset: WALPos, data: WALBytes) -> Result<(), ()> {
let (res, data) = self
.aiomgr
.write(self.fd.as_raw_fd(), offset, data, None)
.await;
res.or_else(|_| Err(())).and_then(|nwrote| {
if nwrote == data.len() {
Ok(())
} else {
Err(())
}
})
}
async fn read(
&self, offset: WALPos, length: usize,
) -> Result<Option<WALBytes>, ()> {
let (res, data) = self
.aiomgr
.read(self.fd.as_raw_fd(), offset, length, None)
.await;
res.or_else(|_| Err(())).and_then(|nread| {
Ok(if nread == length { Some(data) } else { None })
})
}
}
pub struct WALStoreAIO {
rootfd: OwnedFd,
aiomgr: Arc<AIOManager>,
}
unsafe impl Send for WALStoreAIO {}
impl WALStoreAIO {
pub fn new(
wal_dir: &str, truncate: bool, rootfd: Option<BorrowedFd>,
aiomgr: Option<AIOManager>,
) -> Result<Self, ()> {
let aiomgr = Arc::new(aiomgr.ok_or(Err(())).or_else(
|_: Result<AIOManager, ()>| {
AIOBuilder::default().build().or(Err(()))
},
)?);
if truncate {
let _ = std::fs::remove_dir_all(wal_dir);
}
let walfd;
match rootfd {
None => {
match mkdir(
wal_dir,
Mode::S_IRUSR | Mode::S_IWUSR | Mode::S_IXUSR,
) {
Err(e) => {
if truncate {
panic!("error while creating directory: {}", e)
}
}
Ok(_) => (),
}
walfd = match open(
wal_dir,
OFlag::O_DIRECTORY | OFlag::O_PATH,
Mode::empty(),
) {
Ok(fd) => fd,
Err(_) => panic!("error while opening the WAL directory"),
}
}
Some(fd) => {
let dirstr = std::ffi::CString::new(wal_dir).unwrap();
let ret = unsafe {
libc::mkdirat(
fd.as_raw_fd(),
dirstr.as_ptr(),
libc::S_IRUSR | libc::S_IWUSR | libc::S_IXUSR,
)
};
if ret != 0 {
if truncate {
panic!("error while creating directory")
}
}
walfd = match nix::fcntl::openat(
fd.as_raw_fd(),
wal_dir,
OFlag::O_DIRECTORY | OFlag::O_PATH,
Mode::empty(),
) {
Ok(fd) => fd,
Err(_) => panic!("error while opening the WAL directory"),
}
}
}
Ok(WALStoreAIO {
rootfd: unsafe { OwnedFd::from_raw_fd(walfd) },
aiomgr,
})
}
}
#[async_trait(?Send)]
impl WALStore for WALStoreAIO {
type FileNameIter = std::vec::IntoIter<String>;
async fn open_file(
&self, filename: &str, _touch: bool,
) -> Result<Box<dyn WALFile>, ()> {
let filename = filename.to_string();
WALFileAIO::new(self.rootfd.as_fd(), &filename, self.aiomgr.clone())
.and_then(|f| Ok(Box::new(f) as Box<dyn WALFile>))
}
async fn remove_file(&self, filename: String) -> Result<(), ()> {
unlinkat(
Some(self.rootfd.as_raw_fd()),
filename.as_str(),
UnlinkatFlags::NoRemoveDir,
)
.or_else(|_| Err(()))
}
fn enumerate_files(&self) -> Result<Self::FileNameIter, ()> {
let mut logfiles = Vec::new();
for ent in nix::dir::Dir::openat(
self.rootfd.as_raw_fd(),
"./",
OFlag::empty(),
Mode::empty(),
)
.unwrap()
.iter()
{
logfiles
.push(ent.unwrap().file_name().to_str().unwrap().to_string())
}
Ok(logfiles.into_iter())
}
}