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Don't use generics bounded by trait

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This commit is contained in:
Arpad Müller
2023-08-28 11:05:06 +02:00
parent a362ab9169
commit e983b3cc2e
1 changed files with 46 additions and 40 deletions
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86
pageserver/src/tenant/block_io.rs
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@@ -150,53 +150,59 @@ pub struct FileBlockReader<F> {
file_id: page_cache::FileId,
}
impl<F> FileBlockReader<F>
where
F: FileExt,
{
impl<F> FileBlockReader<F> {
pub fn new(file: F) -> Self {
let file_id = page_cache::next_file_id();
FileBlockReader { file_id, file }
}
/// Read a page from the underlying file into given buffer.
fn fill_buffer(&self, buf: &mut [u8], blkno: u32) -> Result<(), std::io::Error> {
assert!(buf.len() == PAGE_SZ);
self.file.read_exact_at(buf, blkno as u64 * PAGE_SZ as u64)
}
/// Read a block.
///
/// Returns a "lease" object that can be used to
/// access to the contents of the page. (For the page cache, the
/// lease object represents a lock on the buffer.)
pub async fn read_blk(&self, blknum: u32) -> Result<BlockLease, std::io::Error> {
// Look up the right page
let cache = page_cache::get();
loop {
match cache
.read_immutable_buf(self.file_id, blknum)
.await
.map_err(|e| {
std::io::Error::new(
std::io::ErrorKind::Other,
format!("Failed to read immutable buf: {e:#}"),
)
})? {
ReadBufResult::Found(guard) => break Ok(guard.into()),
ReadBufResult::NotFound(mut write_guard) => {
// Read the page from disk into the buffer
self.fill_buffer(write_guard.deref_mut(), blknum)?;
write_guard.mark_valid();
// Swap for read lock
continue;
}
};
}
}
}
macro_rules! impls {
(FileBlockReader<$ty:ty>) => {
impl FileBlockReader<$ty> {
/// Read a page from the underlying file into given buffer.
fn fill_buffer(&self, buf: &mut [u8], blkno: u32) -> Result<(), std::io::Error> {
assert!(buf.len() == PAGE_SZ);
self.file.read_exact_at(buf, blkno as u64 * PAGE_SZ as u64)
}
/// Read a block.
///
/// Returns a "lease" object that can be used to
/// access to the contents of the page. (For the page cache, the
/// lease object represents a lock on the buffer.)
pub async fn read_blk(&self, blknum: u32) -> Result<BlockLease, std::io::Error> {
// Look up the right page
let cache = page_cache::get();
loop {
match cache
.read_immutable_buf(self.file_id, blknum)
.await
.map_err(|e| {
std::io::Error::new(
std::io::ErrorKind::Other,
format!("Failed to read immutable buf: {e:#}"),
)
})? {
ReadBufResult::Found(guard) => break Ok(guard.into()),
ReadBufResult::NotFound(mut write_guard) => {
// Read the page from disk into the buffer
self.fill_buffer(write_guard.deref_mut(), blknum)?;
write_guard.mark_valid();
// Swap for read lock
continue;
}
};
}
}
}
};
}
impls!(FileBlockReader<File>);
impls!(FileBlockReader<VirtualFile>);
impl BlockReader for FileBlockReader<File> {
fn block_cursor(&self) -> BlockCursor<'_> {
BlockCursor::new(BlockReaderRef::FileBlockReaderFile(self))