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use std::fs::DirBuilder;
use std::io::prelude::*;
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::sync::Mutex;
use async_std::fs as afs;
use async_std::future::Future;
use async_std::task::{self, Context, JoinHandle, Poll};
use futures::io::AsyncWrite;
use futures::prelude::*;
use memmap::MmapMut;
use ssri::{Algorithm, Integrity, IntegrityOpts};
use tempfile::NamedTempFile;
use crate::content::path;
use crate::errors::{Internal, Result};
pub const MAX_MMAP_SIZE: usize = 1024 * 1024;
pub struct Writer {
cache: PathBuf,
builder: IntegrityOpts,
mmap: Option<MmapMut>,
tmpfile: NamedTempFile,
}
impl Writer {
pub fn new(cache: &Path, algo: Algorithm, size: Option<usize>) -> Result<Writer> {
let cache_path = cache.to_path_buf();
let mut tmp_path = cache_path.clone();
tmp_path.push("tmp");
DirBuilder::new()
.recursive(true)
.create(&tmp_path)
.to_internal()?;
let tmpfile = NamedTempFile::new_in(tmp_path).to_internal()?;
let mmap = if let Some(size) = size {
if size <= MAX_MMAP_SIZE {
unsafe { MmapMut::map_mut(tmpfile.as_file()).ok() }
} else {
None
}
} else {
None
};
Ok(Writer {
cache: cache_path,
builder: IntegrityOpts::new().algorithm(algo),
tmpfile,
mmap,
})
}
pub fn close(self) -> Result<Integrity> {
let sri = self.builder.result();
let cpath = path::content_path(&self.cache, &sri);
DirBuilder::new()
.recursive(true)
// Safe unwrap. cpath always has multiple segments
.create(cpath.parent().unwrap())
.to_internal()?;
let res = self.tmpfile.persist(&cpath).to_internal();
if res.is_err() {
// We might run into conflicts sometimes when persisting files.
// This is ok. We can deal. Let's just make sure the destination
// file actually exists, and we can move on.
std::fs::metadata(cpath).to_internal()?;
}
Ok(sri)
}
}
impl Write for Writer {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
self.builder.input(buf);
if let Some(mmap) = &mut self.mmap {
mmap.copy_from_slice(buf);
Ok(buf.len())
} else {
self.tmpfile.write(buf)
}
}
fn flush(&mut self) -> std::io::Result<()> {
self.tmpfile.flush()
}
}
pub struct AsyncWriter(Mutex<State>);
enum State {
Idle(Option<Inner>),
Busy(JoinHandle<State>),
}
struct Inner {
cache: PathBuf,
builder: IntegrityOpts,
tmpfile: NamedTempFile,
mmap: Option<MmapMut>,
buf: Vec<u8>,
last_op: Option<Operation>,
}
enum Operation {
Write(std::io::Result<usize>),
Flush(std::io::Result<()>),
}
impl AsyncWriter {
#[allow(clippy::new_ret_no_self)]
#[allow(clippy::needless_lifetimes)]
pub async fn new(cache: &Path, algo: Algorithm, size: Option<usize>) -> Result<AsyncWriter> {
let cache_path = cache.to_path_buf();
let mut tmp_path = cache_path.clone();
tmp_path.push("tmp");
afs::DirBuilder::new()
.recursive(true)
.create(&tmp_path)
.await
.to_internal()?;
let tmpfile = task::spawn_blocking(|| NamedTempFile::new_in(tmp_path))
.await
.to_internal()?;
let mmap = if let Some(size) = size {
if size <= MAX_MMAP_SIZE {
unsafe { MmapMut::map_mut(tmpfile.as_file()).ok() }
} else {
None
}
} else {
None
};
Ok(AsyncWriter(Mutex::new(State::Idle(Some(Inner {
cache: cache_path,
builder: IntegrityOpts::new().algorithm(algo),
mmap,
tmpfile,
buf: vec![],
last_op: None,
})))))
}
pub async fn close(self) -> Result<Integrity> {
// NOTE: How do I even get access to `inner` safely???
// let inner = ???;
// Blocking, but should be a very fast op.
Ok(futures::future::poll_fn(|cx| {
let state = &mut *self.0.lock().unwrap();
loop {
match state {
State::Idle(opt) => match opt.take() {
None => return Poll::Ready(None),
Some(inner) => {
let (s, r) = futures::channel::oneshot::channel();
let tmpfile = inner.tmpfile;
let sri = inner.builder.result();
let cpath = path::content_path(&inner.cache, &sri);
// Start the operation asynchronously.
*state = State::Busy(task::spawn_blocking(|| {
let res = std::fs::DirBuilder::new()
.recursive(true)
// Safe unwrap. cpath always has multiple segments
.create(cpath.parent().unwrap())
.with_context(|| {
format!(
"building directory {} failed",
cpath.parent().unwrap().display()
)
});
if res.is_err() {
let _ = s.send(res.map(|_| sri));
} else {
let res = tmpfile.persist(&cpath).with_context(|| {
String::from("persisting tempfile failed")
});
if res.is_err() {
// We might run into conflicts
// sometimes when persisting files.
// This is ok. We can deal. Let's just
// make sure the destination file
// actually exists, and we can move
// on.
let _ = s.send(
std::fs::metadata(cpath)
.with_context(|| {
String::from("File still doesn't exist")
})
.map(|_| sri),
);
} else {
let _ = s.send(res.map(|_| sri));
}
}
State::Idle(None)
}));
return Poll::Ready(Some(r));
}
},
// Poll the asynchronous operation the file is currently blocked on.
State::Busy(task) => *state = futures::ready!(Pin::new(task).poll(cx)),
}
}
})
.map(|opt| opt.ok_or_else(|| io_error("file closed")))
.await
.to_internal()?
.await
.to_internal()??)
}
}
impl AsyncWrite for AsyncWriter {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<std::io::Result<usize>> {
let state = &mut *self.0.lock().unwrap();
loop {
match state {
State::Idle(opt) => {
// Grab a reference to the inner representation of the file or return an error
// if the file is closed.
let inner = opt.as_mut().ok_or_else(|| io_error("file closed"))?;
// Check if the operation has completed.
if let Some(Operation::Write(res)) = inner.last_op.take() {
let n = res?;
// If more data was written than is available in the buffer, let's retry
// the write operation.
if n <= buf.len() {
return Poll::Ready(Ok(n));
}
} else {
let mut inner = opt.take().unwrap();
// Set the length of the inner buffer to the length of the provided buffer.
if inner.buf.len() < buf.len() {
inner.buf.reserve(buf.len() - inner.buf.len());
}
unsafe {
inner.buf.set_len(buf.len());
}
// Copy the data to write into the inner buffer.
inner.buf[..buf.len()].copy_from_slice(buf);
// Start the operation asynchronously.
*state = State::Busy(task::spawn_blocking(|| {
inner.builder.input(&inner.buf);
if let Some(mmap) = &mut inner.mmap {
mmap.copy_from_slice(&inner.buf);
inner.last_op = Some(Operation::Write(Ok(inner.buf.len())));
State::Idle(Some(inner))
} else {
let res = inner.tmpfile.write(&inner.buf);
inner.last_op = Some(Operation::Write(res));
State::Idle(Some(inner))
}
}));
}
}
// Poll the asynchronous operation the file is currently blocked on.
State::Busy(task) => *state = futures::ready!(Pin::new(task).poll(cx)),
}
}
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
let state = &mut *self.0.lock().unwrap();
loop {
match state {
State::Idle(opt) => {
// Grab a reference to the inner representation of the file or return if the
// file is closed.
let inner = match opt.as_mut() {
None => return Poll::Ready(Ok(())),
Some(s) => s,
};
// Check if the operation has completed.
if let Some(Operation::Flush(res)) = inner.last_op.take() {
return Poll::Ready(res);
} else {
let mut inner = opt.take().unwrap();
if let Some(mmap) = &inner.mmap {
match mmap.flush_async() {
Ok(_) => (),
Err(e) => return Poll::Ready(Err(e)),
};
}
// Start the operation asynchronously.
*state = State::Busy(task::spawn_blocking(|| {
let res = inner.tmpfile.flush();
inner.last_op = Some(Operation::Flush(res));
State::Idle(Some(inner))
}));
}
}
// Poll the asynchronous operation the file is currently blocked on.
State::Busy(task) => *state = futures::ready!(Pin::new(task).poll(cx)),
}
}
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
let state = &mut *self.0.lock().unwrap();
loop {
match state {
State::Idle(opt) => {
// Grab a reference to the inner representation of the file or return if the
// file is closed.
let inner = match opt.take() {
None => return Poll::Ready(Ok(())),
Some(s) => s,
};
// Start the operation asynchronously.
*state = State::Busy(task::spawn_blocking(|| {
drop(inner);
State::Idle(None)
}));
}
// Poll the asynchronous operation the file is currently blocked on.
State::Busy(task) => *state = futures::ready!(Pin::new(task).poll(cx)),
}
}
}
}
fn io_error(err: impl Into<Box<dyn std::error::Error + Send + Sync>>) -> std::io::Error {
std::io::Error::new(std::io::ErrorKind::Other, err)
}
#[cfg(test)]
mod tests {
use super::*;
use async_std::task;
use tempfile;
#[test]
fn basic_write() {
let tmp = tempfile::tempdir().unwrap();
let dir = tmp.path().to_owned();
let mut writer = Writer::new(&dir, Algorithm::Sha256, None).unwrap();
writer.write_all(b"hello world").unwrap();
let sri = writer.close().unwrap();
assert_eq!(sri.to_string(), Integrity::from(b"hello world").to_string());
assert_eq!(
std::fs::read(path::content_path(&dir, &sri)).unwrap(),
b"hello world"
);
}
#[test]
fn basic_async_write() {
let tmp = tempfile::tempdir().unwrap();
let dir = tmp.path().to_owned();
task::block_on(async {
let mut writer = AsyncWriter::new(&dir, Algorithm::Sha256, None)
.await
.unwrap();
writer.write_all(b"hello world").await.unwrap();
let sri = writer.close().await.unwrap();
assert_eq!(sri.to_string(), Integrity::from(b"hello world").to_string());
assert_eq!(
std::fs::read(path::content_path(&dir, &sri)).unwrap(),
b"hello world"
);
});
}
}