enable setting compression level

src/core/index_meta.rs

@@ -326,7 +326,7 @@ pub struct IndexMeta {
     pub payload: Option<String>,
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug)]
 struct UntrackedIndexMeta {
     pub segments: Vec<InnerSegmentMeta>,
     #[serde(default)]
@@ -395,6 +395,7 @@ mod tests {
     use super::IndexMeta;
     use crate::core::index_meta::UntrackedIndexMeta;
     use crate::schema::{Schema, TEXT};
+    use crate::store::ZstdCompressor;
     use crate::{IndexSettings, IndexSortByField, Order};
 
     #[test]
@@ -428,4 +429,60 @@ mod tests {
         assert_eq!(index_metas.schema, deser_meta.schema);
         assert_eq!(index_metas.opstamp, deser_meta.opstamp);
     }
+
+    #[test]
+    fn test_serialize_metas_zstd_compressor() {
+        let schema = {
+            let mut schema_builder = Schema::builder();
+            schema_builder.add_text_field("text", TEXT);
+            schema_builder.build()
+        };
+        let index_metas = IndexMeta {
+            index_settings: IndexSettings {
+                sort_by_field: Some(IndexSortByField {
+                    field: "text".to_string(),
+                    order: Order::Asc,
+                }),
+                docstore_compression: crate::store::Compressor::Zstd(ZstdCompressor {
+                    compression_level: Some(4),
+                }),
+                docstore_blocksize: 1_000_000,
+            },
+            segments: Vec::new(),
+            schema,
+            opstamp: 0u64,
+            payload: None,
+        };
+        let json = serde_json::ser::to_string(&index_metas).expect("serialization failed");
+        assert_eq!(
+            json,
+            r#"{"index_settings":{"sort_by_field":{"field":"text","order":"Asc"},"docstore_compression":"zstd(compression_level=4)","docstore_blocksize":1000000},"segments":[],"schema":[{"name":"text","type":"text","options":{"indexing":{"record":"position","fieldnorms":true,"tokenizer":"default"},"stored":false,"fast":false}}],"opstamp":0}"#
+        );
+
+        let deser_meta: UntrackedIndexMeta = serde_json::from_str(&json).unwrap();
+        assert_eq!(index_metas.index_settings, deser_meta.index_settings);
+        assert_eq!(index_metas.schema, deser_meta.schema);
+        assert_eq!(index_metas.opstamp, deser_meta.opstamp);
+    }
+
+    #[test]
+    fn test_serialize_metas_invalid_comp() {
+        let json = r#"{"index_settings":{"sort_by_field":{"field":"text","order":"Asc"},"docstore_compression":"zsstd","docstore_blocksize":1000000},"segments":[],"schema":[{"name":"text","type":"text","options":{"indexing":{"record":"position","fieldnorms":true,"tokenizer":"default"},"stored":false,"fast":false}}],"opstamp":0}"#;
+
+        let err = serde_json::from_str::<UntrackedIndexMeta>(&json).unwrap_err();
+        assert_eq!(
+            err.to_string(),
+            "unknown variant `zsstd`, expected one of `none`, `lz4`, `brotli`, `snappy`, `zstd`, \
+             `zstd(compression_level=5)` at line 1 column 96"
+                .to_string()
+        );
+
+        let json = r#"{"index_settings":{"sort_by_field":{"field":"text","order":"Asc"},"docstore_compression":"zstd(bla=10)","docstore_blocksize":1000000},"segments":[],"schema":[{"name":"text","type":"text","options":{"indexing":{"record":"position","fieldnorms":true,"tokenizer":"default"},"stored":false,"fast":false}}],"opstamp":0}"#;
+
+        let err = serde_json::from_str::<UntrackedIndexMeta>(&json).unwrap_err();
+        assert_eq!(
+            err.to_string(),
+            "unknown zstd option \"bla\" at line 1 column 103".to_string()
+        );
+    }
 }

src/indexer/merger.rs

@@ -1073,7 +1073,7 @@ impl IndexMerger {
                     //
                     // take 7 in order to not walk over all checkpoints.
                     || store_reader.block_checkpoints().take(7).count() < 6
-                    || store_reader.compressor() != store_writer.compressor()
+                    || store_reader.decompressor() != store_writer.compressor().into()
                 {
                     for doc_bytes_res in store_reader.iter_raw(reader.alive_bitset()) {
                         let doc_bytes = doc_bytes_res?;

src/store/compression_zstd_block.rs

@@ -4,7 +4,11 @@ use zstd::bulk::{compress_to_buffer, decompress_to_buffer};
 use zstd::DEFAULT_COMPRESSION_LEVEL;
 
 #[inline]
-pub fn compress(uncompressed: &[u8], compressed: &mut Vec<u8>) -> io::Result<()> {
+pub fn compress(
+    uncompressed: &[u8],
+    compressed: &mut Vec<u8>,
+    compression_level: Option<i32>,
+) -> io::Result<()> {
     let count_size = std::mem::size_of::<u32>();
     let max_size = zstd::zstd_safe::compress_bound(uncompressed.len()) + count_size;
 
@@ -14,7 +18,7 @@ pub fn compress(uncompressed: &[u8], compressed: &mut Vec<u8>) -> io::Result<()>
     let compressed_size = compress_to_buffer(
         uncompressed,
         &mut compressed[count_size..],
-        DEFAULT_COMPRESSION_LEVEL,
+        compression_level.unwrap_or(DEFAULT_COMPRESSION_LEVEL),
     )?;
 
     compressed[0..count_size].copy_from_slice(&(uncompressed.len() as u32).to_le_bytes());