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make the read path async, except the read_at impl

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This commit is contained in:
Christian Schwarz
2023-08-29 10:50:21 +02:00
parent 5be0f9d69a
commit 235baffbf4
2 changed files with 34 additions and 1 deletions
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3
pageserver/src/tenant/ephemeral_file.rs
View File

@@ -87,7 +87,8 @@ impl EphemeralFile {
let buf: &mut [u8] = write_guard.deref_mut();
debug_assert_eq!(buf.len(), PAGE_SZ);
self.file
.read_exact_at(&mut buf[..], blknum as u64 * PAGE_SZ as u64)?;
.read_exact_at_async(&mut buf[..], blknum as u64 * PAGE_SZ as u64)
.await?;
write_guard.mark_valid();
// Swap for read lock

32
pageserver/src/virtual_file.rs
View File

@@ -406,6 +406,27 @@ impl VirtualFile {
Ok(())
}
// Copied from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#117-135
pub async fn read_exact_at_async(&self, mut buf: &mut [u8], mut offset: u64) -> Result<(), Error> {
while !buf.is_empty() {
match self.read_at_async(buf, offset).await {
Ok(0) => {
return Err(Error::new(
std::io::ErrorKind::UnexpectedEof,
"failed to fill whole buffer",
))
}
Ok(n) => {
buf = &mut buf[n..];
offset += n as u64;
}
Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => {}
Err(e) => return Err(e),
}
}
Ok(())
}
// Copied from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#219-235
pub fn write_all_at(&self, mut buf: &[u8], mut offset: u64) -> Result<(), Error> {
while !buf.is_empty() {
@@ -437,6 +458,17 @@ impl VirtualFile {
result
}
async fn read_at_async(&self, buf: &mut [u8], offset: u64) -> Result<usize, Error> {
// TODO: don't block here
let result = self.with_file("read", |file| file.read_at(buf, offset))?;
if let Ok(size) = result {
STORAGE_IO_SIZE
.with_label_values(&["read", &self.tenant_id, &self.timeline_id])
.add(size as i64);
}
result
}
pub fn write_at(&self, buf: &[u8], offset: u64) -> Result<usize, Error> {
let result = self.with_file("write", |file| file.write_at(buf, offset))?;
if let Ok(size) = result {