add test write/read + fix write

src/db.rs

@@ -1,10 +1,9 @@
 use std::{
     fs,
-    io::{self, Cursor, Read, Seek, SeekFrom, Write},
+    io::{self, Cursor, Read, Seek, Write},
     marker::PhantomData,
     path::Path,
 };
-use zstd::stream::{raw::Operation, zio};
 
 type LSize = u32;
 const LEN_SIZE: usize = std::mem::size_of::<LSize>();
@@ -38,44 +37,44 @@ impl Default for WriterOpts {
             compress_lvl: 1,
             data_buf_size: 500 * 1024 * 1024,
             out_buf_size: 200 * 1024 * 1024,
-            current_buf_size: 20 * 1024,
+            current_buf_size: 20 * 1024 * 1024,
         }
     }
 }
 
-pub struct Writer<'a, T>
+pub struct Writer<T>
 where
     T: bincode::Encode,
 {
     out: io::BufWriter<fs::File>,
     data_buf: Cursor<Vec<u8>>,
-    cur_buf_z: zio::Writer<Cursor<Vec<u8>>, zstd::stream::raw::Encoder<'a>>,
     table: Vec<LSize>,
+    compress_lvl: i32,
+    current_buf_size: usize,
     _t: PhantomData<*const T>,
 }
 
-impl<T> Writer<'_, T>
+impl<T> Writer<T>
 where
-    T: bincode::Encode,
+    T: bincode::Encode + std::fmt::Debug,
 {
     pub fn new<P: AsRef<Path>>(path: P, opts: WriterOpts) -> Result<Self, String> {
         let out = fs::File::create(path).str_err()?;
         let out = io::BufWriter::with_capacity(opts.out_buf_size, out);
         let data_buf: Vec<u8> = Vec::with_capacity(opts.data_buf_size);
-        let cur_buf_raw: Vec<u8> = Vec::with_capacity(opts.current_buf_size);
         let data_buf = Cursor::new(data_buf);
-        let cur_buf_raw = Cursor::new(cur_buf_raw);
-
-        let zencoder = zstd::stream::raw::Encoder::new(opts.compress_lvl).str_err()?;
-        let cur_buf_z = zstd::stream::zio::Writer::new(cur_buf_raw, zencoder);
 
+        let compress_lvl = opts.compress_lvl;
+        let current_buf_size = opts.current_buf_size;
+        
         let table: Vec<LSize> = vec![];
 
         Ok(Self {
             out,
             data_buf,
-            cur_buf_z,
             table,
+            compress_lvl,
+            current_buf_size,
             _t: PhantomData,
         })
     }
@@ -84,22 +83,26 @@ where
         let pos: LSize = self.data_buf.position() as LSize;
 
         let item_data = bincode::encode_to_vec(item, BINCODE_CFG).str_err()?;
-
-        let zencoder = self.cur_buf_z.operation_mut();
-        zencoder.reinit().str_err()?;
+        
+        let cur_buf_raw: Vec<u8> = Vec::with_capacity(self.current_buf_size);
+        let cur_buf_raw = Cursor::new(cur_buf_raw);
+        let mut zencoder = zstd::stream::raw::Encoder::new(self.compress_lvl).str_err()?;
         zencoder
             .set_pledged_src_size(item_data.len() as u64)
             .str_err()?;
 
-        self.cur_buf_z.write_all(&item_data).str_err()?;
-        self.cur_buf_z.finish().str_err()?;
-        self.cur_buf_z.flush().str_err()?;
+        let mut cur_buf_z = zstd::stream::zio::Writer::new(cur_buf_raw, zencoder);
+        cur_buf_z.write_all(&item_data).str_err()?;
+        cur_buf_z.finish().str_err()?;
+        cur_buf_z.flush().str_err()?;
 
         self.table.push(pos);
-        let cur_buf_raw = self.cur_buf_z.writer_mut();
+        let (mut cur_buf_raw, _) = cur_buf_z.into_inner();
         let size = cur_buf_raw.position();
+        
         cur_buf_raw.set_position(0);
-        io::copy(&mut cur_buf_raw.take(size), &mut self.data_buf).str_err()?;
+        let mut chunk_reader = cur_buf_raw.take(size);
+        io::copy(&mut chunk_reader, &mut self.data_buf).str_err()?;
 
         Ok(())
     }
@@ -186,7 +189,9 @@ where
         } else {
             let tab_pos: u64 = (index * LEN_SIZE).try_into().str_err()?;
             let mut pos_curr_data: [u8; LEN_SIZE] = [0; LEN_SIZE];
-            self.input.seek(SeekFrom::Start(tab_pos)).str_err()?;
+            let cur_pos = self.input.stream_position().str_err()? as i64;
+            self.input.seek_relative((tab_pos as i64) - cur_pos).str_err()?;
+            
             self.input.read_exact(&mut pos_curr_data).str_err()?;
             LSize::from_le_bytes(pos_curr_data)
         };
@@ -199,8 +204,9 @@ where
         let data_len = data_pos_next - data_pos;
 
         // read & unpack item data
+        let cur_pos = self.input.stream_position().str_err()? as i64;
         self.input
-            .seek(SeekFrom::Start(data_pos as u64))
+            .seek_relative((data_pos as i64) - cur_pos)
             .str_err()?;
         let reader = self.input.by_ref().take(data_len as u64);
         let data = zstd::decode_all(reader).str_err()?;
@@ -211,3 +217,44 @@ where
         Ok(item.0)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use rand::RngCore;
+
+    use super::*;
+
+    #[derive(bincode::Encode, bincode::Decode, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+    struct TestData {
+        num: u64,
+    }
+
+    fn gen_data(count: usize) -> impl Iterator<Item = TestData> {
+        (0..count).into_iter().map(|i| TestData{ num: i as u64})
+    }
+
+    #[test]
+    fn test_write_read() {
+        let mut rng = rand::thread_rng();
+        let tempfile = std::env::temp_dir().with_file_name(format!("test-{}.tmp", rng.next_u32()));
+        let opts = WriterOpts { compress_lvl: 1, data_buf_size: 10 * 1024 * 1024, out_buf_size: 10 * 1024 * 1024, current_buf_size: 4096 };
+        let mut writer: Writer<TestData> = Writer::new(&tempfile, opts).expect("new writer");
+
+        let items_iter = gen_data(5);
+        let items: Vec<TestData> = items_iter.collect();
+
+        writer.load(&mut items.clone().into_iter()).expect("load");
+        writer.finish().expect("finish write");
+
+        let mut reader: Reader<TestData> = Reader::new(&tempfile, 2048).expect("new reader");
+        assert_eq!(items.len(), reader.len());
+
+        for (idx,item) in items.iter().enumerate() {
+            let ritem = reader.get(idx).expect("get");
+            assert_eq!(*item, ritem);
+        }
+
+        let r = fs::remove_file(tempfile);
+        drop(r);
+    }
+}