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use std::path::{Path,PathBuf};
use std::fs::File;
use std::io::Seek;
use crate::merge::Merge;
use crate::record::OwnedRecord;
use crate::key_reader::*;
use crate::Wildcard;
use byteorder::ByteOrder;
pub struct DatabaseReader
{
_dir: PathBuf,
txes: Vec<(PathBuf,Reader)>,
}
impl DatabaseReader
{
pub fn new(dir: &Path)
-> std::io::Result<DatabaseReader>
{
Self::new_opts(dir, true)
}
pub fn without_main_db(dir: &Path)
-> std::io::Result<DatabaseReader>
{
Self::new_opts(dir, false)
}
fn new_opts(dir: &Path, include_main_db: bool)
-> std::io::Result<DatabaseReader>
{
let dir_reader = std::fs::read_dir(dir)?;
let mut paths = vec!();
for entry in dir_reader
{
let entry = entry?;
if let Some(s) = entry.file_name().to_str()
{
if s.starts_with("tx.") && !s.ends_with(".tmp")
{
paths.push(entry.path());
}
}
}
paths.sort();
let mut txes = Vec::with_capacity(paths.len());
if include_main_db
{
let main_db_name = dir.join("main");
let mut f = File::open(&main_db_name)?;
let len = f.seek(std::io::SeekFrom::End(0))? as usize;
if len == 0
{
eprintln!("disregarding main database, it is zero length");
}
else
{
let main_db = Reader::new(f)?;
txes.push( (main_db_name, main_db) );
}
}
for p in paths
{
let mut f = File::open(&p)?;
let len = f.seek(std::io::SeekFrom::End(0))? as usize;
if len == 0
{
eprintln!("disregarding {:?}, it is zero length", p);
continue;
}
let r = Reader::new(f)?;
txes.push( (p,r) );
}
Ok(DatabaseReader
{
txes,
_dir: dir.to_owned(),
})
}
pub fn transaction_paths(&self) -> Vec<PathBuf>
{
self.txes
.iter()
.map( |e| e.0.clone())
.collect()
}
pub fn get<'rdr, 'k>(&'rdr self, key: &'k str)
-> DatabaseKeyReader<'rdr, 'k, std::ops::RangeInclusive<&'k str>>
{
self.get_range( key ..= key )
}
pub fn get_range<'d, 'r, RB>(&'d self, range: RB)
-> DatabaseKeyReader<'d, 'r, RB>
where
RB: std::ops::RangeBounds<&'r str> + Clone
{
let mut readers = Vec::with_capacity(self.txes.len());
for tx in &self.txes
{
readers.push( tx.1.get_range(range.clone()) );
}
let merge = Merge::new(
readers,
|a, b|
{
a.key().cmp(b.key())
.then_with(
||
byteorder::BigEndian::read_u64(a.value())
.cmp(&byteorder::BigEndian::read_u64(b.value()))
)
},
);
DatabaseKeyReader
{
_db: self,
merge: Box::new(merge),
}
}
pub fn get_filter<'d, 'k>(&'d self, wildcard: &'k Wildcard)
-> DatabaseKeyReader<'d, 'k, std::ops::RangeFrom<&'k str>>
{
let mut readers = Vec::with_capacity(self.txes.len());
for tx in &self.txes
{
readers.push( tx.1.get_filter(wildcard) );
}
let merge = Merge::new(
readers,
|a, b|
{
a.key().cmp(b.key())
.then_with(
||
byteorder::BigEndian::read_u64(a.value())
.cmp(&byteorder::BigEndian::read_u64(b.value()))
)
},
);
DatabaseKeyReader
{
_db: self,
merge: Box::new(merge),
}
}
}
pub struct DatabaseKeyReader<'d, 'r, RB>
where
RB: std::ops::RangeBounds<&'r str>
{
_db: &'d DatabaseReader,
merge: Box<Merge<
StringKeyRangeReader<'d, 'r, RB>, OwnedRecord,
>>,
}
impl<'d, 'r, RB> Iterator for DatabaseKeyReader<'d, 'r, RB>
where
RB: std::ops::RangeBounds<&'r str>
{
type Item = OwnedRecord;
fn next(&mut self) -> Option<Self::Item>
{
self.merge.next()
}
}