62 lines
2.1 KiB
Rust
62 lines
2.1 KiB
Rust
use async_trait::async_trait;
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use tokio::fs::File;
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use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt, SeekFrom};
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use crate::store::{FilePosition, Result};
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#[async_trait]
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pub(crate) trait CursorCanRead<T> {
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fn file(&mut self) -> &mut File;
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fn eof_file_position(&self) -> FilePosition;
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async fn read_bytes(&mut self, bytes: &mut [u8]) -> Result<()> {
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self.file().read_exact(bytes).await?;
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Ok(())
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}
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async fn get_bytes(&mut self, count: usize) -> Result<Vec<u8>> {
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let mut result: Vec<u8> = Vec::with_capacity(count);
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self.read_bytes(&mut result).await?;
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Ok(result)
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}
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async fn seek_to(&mut self, file_position: FilePosition) -> Result<FilePosition> {
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let file_position = self.file().seek(SeekFrom::Start(file_position)).await?;
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Ok(file_position)
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}
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// Start of the file i.e. the Header, not the entries.
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async fn seek_to_start(&mut self) -> Result<FilePosition> {
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let file_position = self.file().seek(SeekFrom::Start(0)).await?;
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Ok(file_position)
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}
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async fn seek_to_end(&mut self) -> Result<FilePosition> {
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let file_position = self.file().seek(SeekFrom::End(0)).await?;
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Ok(file_position)
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}
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// Seeks from current position by offset and returns new file position
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async fn seek_by(&mut self, offset: i64) -> Result<FilePosition> {
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let file_position = self.file().seek(SeekFrom::Current(offset)).await?;
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Ok(file_position)
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}
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async fn current_file_position(&mut self) -> Result<FilePosition> {
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let next_file_position: FilePosition = self.file().stream_position().await?;
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Ok(next_file_position)
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}
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async fn is_at_eof(&mut self) -> Result<bool> {
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let current_file_position = self.current_file_position().await?;
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let eof_file_position = self.eof_file_position();
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Ok(current_file_position == eof_file_position)
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}
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}
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#[async_trait]
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pub(crate) trait CursorCanWrite<T>: CursorCanRead<T> {
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async fn write_bytes(&mut self, bytes: &[u8]) -> Result<usize> {
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Ok(self.file().write(bytes).await?)
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}
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}
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