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@@ -0,0 +1,151 @@
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+// Stract is an open source web search engine.
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+// Copyright (C) 2024 Stract ApS
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+//
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+// This program is free software: you can redistribute it and/or modify
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+// it under the terms of the GNU Affero General Public License as
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+// published by the Free Software Foundation, either version 3 of the
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+// License, or (at your option) any later version.
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+//
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+// This program is distributed in the hope that it will be useful,
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+// but WITHOUT ANY WARRANTY; without even the implied warranty of
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+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+// GNU Affero General Public License for more details.
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+//
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+// You should have received a copy of the GNU Affero General Public License
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+// along with this program. If not, see <https://www.gnu.org/licenses/>.
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+
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+use anyhow::Result;
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+use std::{
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+ fs::File,
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+ path::{Path, PathBuf},
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+};
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+
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+pub struct Wal<T> {
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+ writer: file_store::iterable::IterableStoreWriter<T, File>,
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+ path: PathBuf,
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+}
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+
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+impl<T> Wal<T> {
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+ pub fn open<P: AsRef<Path>>(file: P) -> Result<Self> {
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+ let path = file.as_ref().to_path_buf();
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+ let file = if file.as_ref().exists() {
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+ File::open(file)?
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+ } else {
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+ File::create(file)?
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+ };
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+
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+ Ok(Wal {
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+ writer: file_store::iterable::IterableStoreWriter::new(file),
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+ path,
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+ })
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+ }
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+
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+ pub fn clear(&mut self) -> Result<()> {
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+ std::fs::remove_file(&self.path)?;
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+ self.writer = file_store::iterable::IterableStoreWriter::new(File::create(&self.path)?);
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+
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+ Ok(())
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+ }
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+}
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+
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+impl<T> Wal<T>
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+where
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+ T: bincode::Encode,
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+{
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+ pub fn write(&mut self, item: &T) -> Result<()> {
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+ self.writer.write(item)?;
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+ self.writer.flush()?;
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+
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+ Ok(())
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+ }
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+}
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+
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+impl<T> Wal<T>
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+where
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+ T: bincode::Decode,
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+{
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+ pub fn iter(&self) -> Result<WalIterator<T>> {
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+ WalIterator::open(&self.path)
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+ }
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+}
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+
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+pub struct WalIterator<T> {
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+ iter: file_store::iterable::IterableStoreReader<T>,
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+}
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+
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+impl<T> WalIterator<T> {
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+ pub fn open<P: AsRef<Path>>(file: P) -> Result<Self> {
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+ Ok(Self {
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+ iter: file_store::iterable::IterableStoreReader::open(file)?,
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+ })
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+ }
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+}
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+
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+impl<T> Iterator for WalIterator<T>
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+where
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+ T: bincode::Decode,
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+{
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+ type Item = T;
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+
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+ fn next(&mut self) -> Option<Self::Item> {
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+ self.iter.next()
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+ }
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+}
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+
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+#[cfg(test)]
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+mod tests {
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+ use super::*;
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+ use anyhow::Result;
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+
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+ #[test]
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+ fn test_write_read() -> Result<()> {
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+ let mut writer = Wal::open(file_store::gen_temp_path())?;
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+
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+ writer.write(&1u64)?;
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+ writer.write(&2u64)?;
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+ writer.write(&3u64)?;
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+
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+ let res: Vec<_> = writer.iter()?.collect();
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+
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+ assert_eq!(&res, &[1, 2, 3]);
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+
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+ writer.write(&4u64)?;
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+
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+ let res: Vec<_> = writer.iter()?.collect();
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+
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+ assert_eq!(&res, &[1, 2, 3, 4]);
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+
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+ Ok(())
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+ }
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+
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+ #[test]
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+ fn test_empty_write() -> Result<()> {
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+ let writer: Wal<u64> = Wal::open(file_store::gen_temp_path())?;
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+
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+ let res: Vec<_> = writer.iter()?.collect();
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+
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+ assert!(res.is_empty());
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+
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+ Ok(())
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+ }
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+
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+ #[test]
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+ fn test_clear() -> Result<()> {
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+ let mut writer = Wal::open(file_store::gen_temp_path())?;
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+
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+ writer.write(&1u64)?;
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+ writer.write(&2u64)?;
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+ writer.write(&3u64)?;
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+
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+ let res: Vec<_> = writer.iter()?.collect();
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+
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+ assert_eq!(&res, &[1, 2, 3]);
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+
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+ writer.clear()?;
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+
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+ let res: Vec<_> = writer.iter()?.collect();
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+ assert!(res.is_empty());
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+
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+ Ok(())
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+ }
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+}
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Mikkel Denker