compressor test

Author: marvin-j97

Cargo.toml

@@ -26,7 +26,6 @@ serde = ["dep:serde"]
 ahash = "0.8.11"
 byteorder = "1.5.0"
 log = "0.4.22"
-lz4_flex = { version = "0.11.3", optional = true }
 min-max-heap = "1.3.0"
 miniz_oxide = { version = "0.7.4", optional = true }
 path-absolutize = "3.1.1"
@@ -41,6 +40,7 @@ xxhash-rust = { version = "0.8.12", features = ["xxh3"] }
 criterion = "0.5.1"
 rand = "0.8.5"
 test-log = "0.2.16"
+lz4_flex = { version = "0.11.3" }
 
 [[bench]]
 name = "value_log"

src/segment/multi_writer.rs

@@ -51,6 +51,7 @@ impl MultiWriter {
 
     /// Sets the compression method
     #[must_use]
+    #[doc(hidden)]
     pub fn use_compression(mut self, compressor: Arc<dyn Compressor>) -> Self {
         self.compression = Some(compressor.clone());
         self.get_active_writer_mut().compression = Some(compressor);
@@ -111,7 +112,7 @@ impl MultiWriter {
         Ok(())
     }
 
-    /// Writes an item
+    /// Writes an item.
     ///
     /// # Errors
     ///

tests/compression.rs

@@ -0,0 +1,49 @@
+use std::sync::Arc;
+use test_log::test;
+use value_log::{Compressor, Config, IndexWriter, MockIndex, MockIndexWriter, ValueLog};
+
+struct Lz4Compressor;
+impl Compressor for Lz4Compressor {
+    fn compress(&self, bytes: &[u8]) -> Result<Vec<u8>, value_log::CompressError> {
+        Ok(lz4_flex::compress_prepend_size(bytes))
+    }
+
+    fn decompress(&self, bytes: &[u8]) -> Result<Vec<u8>, value_log::DecompressError> {
+        lz4_flex::decompress_size_prepended(bytes)
+            .map_err(|e| value_log::DecompressError(e.to_string()))
+    }
+}
+
+#[test]
+fn compression() -> value_log::Result<()> {
+    let folder = tempfile::tempdir()?;
+    let vl_path = folder.path();
+
+    let index = MockIndex::default();
+
+    let value_log = ValueLog::open(
+        vl_path,
+        Config::default().use_compression(Arc::new(Lz4Compressor)),
+    )?;
+
+    let mut index_writer = MockIndexWriter(index.clone());
+    let mut writer = value_log.get_writer()?;
+
+    let key = "abc";
+    let value = "verycompressable".repeat(1_000);
+
+    let handle = writer.get_next_value_handle();
+    index_writer.insert_indirect(key.as_bytes(), handle.clone(), value.len() as u32)?;
+
+    let written_bytes = writer.write(key, &value)?;
+    assert!(written_bytes < value.len() as u32);
+
+    value_log.register_writer(writer)?;
+
+    assert_eq!(
+        &*value_log.get(&handle)?.expect("value should exist"),
+        value.as_bytes(),
+    );
+
+    Ok(())
+}