File size: 2,539 Bytes
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use std::{
fs::File,
io::{self, BufWriter, Write},
path::Path,
};
use anyhow::{Context, Result};
use byteorder::{BE, WriteBytesExt};
use crate::static_sorted_file_builder::StaticSortedFileBuilderMeta;
pub struct MetaFileBuilder<'a> {
family: u32,
/// Entries in the meta file, tuples of (sequence_number, StaticSortedFileBuilderMetaResult)
entries: Vec<(u32, StaticSortedFileBuilderMeta<'a>)>,
/// Obsolete SST files, represented by their sequence numbers
obsolete_sst_files: Vec<u32>,
}
impl<'a> MetaFileBuilder<'a> {
pub fn new(family: u32) -> Self {
Self {
family,
entries: Vec::new(),
obsolete_sst_files: Vec::new(),
}
}
pub fn add(&mut self, sequence_number: u32, sst: StaticSortedFileBuilderMeta<'a>) {
self.entries.push((sequence_number, sst));
}
pub fn add_obsolete_sst_file(&mut self, sequence_number: u32) {
self.obsolete_sst_files.push(sequence_number);
}
#[tracing::instrument(level = "trace", skip_all)]
pub fn write(self, db_path: &Path, seq: u32) -> Result<File> {
let file = db_path.join(format!("{seq:08}.meta"));
self.write_internal(&file)
.with_context(|| format!("Unable to write meta file {seq:08}.meta"))
}
fn write_internal(mut self, file: &Path) -> io::Result<File> {
let mut file = BufWriter::new(File::create(file)?);
file.write_u32::<BE>(0xFE4ADA4A)?; // Magic number
file.write_u32::<BE>(self.family)?;
self.obsolete_sst_files.sort();
file.write_u32::<BE>(self.obsolete_sst_files.len() as u32)?;
for obsolete_sst in &self.obsolete_sst_files {
file.write_u32::<BE>(*obsolete_sst)?;
}
file.write_u32::<BE>(self.entries.len() as u32)?;
let mut aqmf_offset = 0;
for (sequence_number, sst) in &self.entries {
file.write_u32::<BE>(*sequence_number)?;
file.write_u16::<BE>(sst.key_compression_dictionary_length)?;
file.write_u16::<BE>(sst.value_compression_dictionary_length)?;
file.write_u16::<BE>(sst.block_count)?;
file.write_u64::<BE>(sst.min_hash)?;
file.write_u64::<BE>(sst.max_hash)?;
file.write_u64::<BE>(sst.size)?;
aqmf_offset += sst.aqmf.len();
file.write_u32::<BE>(aqmf_offset as u32)?;
}
for (_, sst) in &self.entries {
file.write_all(&sst.aqmf)?;
}
Ok(file.into_inner()?)
}
}
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