Merge branch 'postcard' into postcard_custom

+ postcard test
works with optional(default/skiped) fileds

by conditional seq deserialization based on flags check

Cargo.lock

@@ -207,25 +207,6 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a32fd6af2b5827bce66c29053ba0e7c42b9dcab01835835058558c10851a46b"
 
-[[package]]
-name = "bincode"
-version = "2.0.0-rc.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f11ea1a0346b94ef188834a65c068a03aec181c94896d481d7a0a40d85b0ce95"
-dependencies = [
- "bincode_derive",
- "serde",
-]
-
-[[package]]
-name = "bincode_derive"
-version = "2.0.0-rc.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e30759b3b99a1b802a7a3aa21c85c3ded5c28e1c83170d82d70f08bbf7f3e4c"
-dependencies = [
- "virtue",
-]
-
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -234,9 +215,9 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitflags"
-version = "2.3.3"
+version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "630be753d4e58660abd17930c71b647fe46c27ea6b63cc59e1e3851406972e42"
+checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
 
 [[package]]
 name = "block-buffer"
@@ -247,6 +228,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "bstringify"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd769563b4ea2953e2825c9e6b7470a5f55f67e0be00030bf3e390a2a6071f64"
+
 [[package]]
 name = "bumpalo"
 version = "3.13.0"
@@ -311,7 +298,6 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 name = "chgk_ledb"
 version = "1.1.0"
 dependencies = [
- "bincode",
  "chgk_ledb_lib",
  "clap 4.3.16",
  "criterion 0.4.0",
@@ -329,7 +315,6 @@ version = "1.1.0"
 dependencies = [
  "async-compression 0.4.1",
  "async_zip",
- "bincode",
  "chgk_ledb_lib",
  "clap 4.3.16",
  "criterion 0.5.1",
@@ -351,7 +336,8 @@ dependencies = [
  "async-compression 0.4.1",
  "async-stream",
  "async_zip",
- "bincode",
+ "bitflags 2.4.0",
+ "bstringify",
  "fmmap",
  "futures",
  "futures-core",
@@ -359,6 +345,7 @@ dependencies = [
  "insta",
  "memmap",
  "pin-project",
+ "postcard",
  "serde",
  "serde_derive",
  "serde_json",
@@ -467,6 +454,12 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2da6da31387c7e4ef160ffab6d5e7f00c42626fe39aea70a7b0f1773f7dd6c1b"
 
+[[package]]
+name = "cobs"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67ba02a97a2bd10f4b59b25c7973101c79642302776489e030cd13cdab09ed15"
+
 [[package]]
 name = "colorchoice"
 version = "1.0.0"
@@ -1248,6 +1241,16 @@ dependencies = [
  "plotters-backend",
 ]
 
+[[package]]
+name = "postcard"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9ee729232311d3cd113749948b689627618133b1c5012b77342c1950b25eaeb"
+dependencies = [
+ "cobs",
+ "serde",
+]
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.17"
@@ -1408,7 +1411,7 @@ version = "0.38.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0a962918ea88d644592894bc6dc55acc6c0956488adcebbfb6e273506b7fd6e5"
 dependencies = [
- "bitflags 2.3.3",
+ "bitflags 2.4.0",
  "errno 0.3.1",
  "libc",
  "linux-raw-sys 0.4.3",
@@ -1701,12 +1704,6 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
-[[package]]
-name = "virtue"
-version = "0.0.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9dcc60c0624df774c82a0ef104151231d37da4962957d691c011c852b2473314"
-
 [[package]]
 name = "walkdir"
 version = "2.3.3"

app/Cargo.toml

@@ -27,6 +27,5 @@ clap = { version = "4.2.7", features = ["derive"] }
 [dev-dependencies]
 criterion = "0.4.0"
 tempfile = "3.3"
-bincode = "^2.0.0-rc.2"
 serde="1.0"
 serde_derive="1.0"

app/benches/db_bench.rs

@@ -1,6 +1,5 @@
 #[macro_use]
 extern crate criterion;
-extern crate bincode;
 extern crate serde;
 extern crate serde_derive;
 extern crate serde_json;
@@ -16,18 +15,7 @@ use tempfile::{tempdir, NamedTempFile};
 
 use serde_derive::{Deserialize, Serialize};
 
-#[derive(
-    bincode::Encode,
-    bincode::Decode,
-    Clone,
-    Debug,
-    PartialEq,
-    Eq,
-    PartialOrd,
-    Ord,
-    Serialize,
-    Deserialize,
-)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 struct TestData {
     num1: u64,
     num2: u64,

app/benches/questions_bench.rs

@@ -1,6 +1,5 @@
 #[macro_use]
 extern crate criterion;
-extern crate bincode;
 extern crate serde;
 extern crate serde_derive;
 extern crate serde_json;

app_async/Cargo.toml

@@ -37,7 +37,6 @@ futures = "0.3"
 [dev-dependencies]
 criterion = { version = "0.5.1", features = ["async_tokio"]}
 tempfile = "3.3"
-bincode = "^2.0.0-rc.2"
 serde="1.0"
 serde_derive="1.0"
 futures = "0.3"

app_async/benches/async_bench.rs

@@ -1,6 +1,5 @@
 #[macro_use]
 extern crate criterion;
-extern crate bincode;
 extern crate serde;
 extern crate serde_derive;
 extern crate tempfile;
@@ -16,18 +15,7 @@ use tempfile::{tempdir, NamedTempFile};
 
 use serde_derive::{Deserialize, Serialize};
 
-#[derive(
-    bincode::Encode,
-    bincode::Decode,
-    Clone,
-    Debug,
-    PartialEq,
-    Eq,
-    PartialOrd,
-    Ord,
-    Serialize,
-    Deserialize,
-)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 struct TestData {
     num1: u64,
     num2: u64,

app_async/benches/questions_async_bench.rs

@@ -1,6 +1,5 @@
 #[macro_use]
 extern crate criterion;
-extern crate bincode;
 extern crate serde;
 extern crate serde_derive;
 extern crate tempfile;

lib/Cargo.toml

@@ -12,40 +12,16 @@ description = "Библиотека для доступа к файлу базы
 [features]
 default = []
 sync = ["zstd", "memmap"]
-async = [
-    "futures",
-    "futures-core",
-    "futures-util",
-    "fmmap",
-    "tokio",
-    "async-compression",
-    "async-stream",
-    "pin-project",
-]
+async = ["futures", "futures-core", "futures-util", "fmmap", "tokio", "async-compression", "async-stream", "pin-project"]
 source = ["zip"]
-source_async = [
-    "async_zip",
-    "tokio",
-    "futures",
-    "futures-core",
-    "futures-util",
-    "async-stream",
-]
+source_async = ["async_zip", "tokio", "futures", "futures-core", "futures-util", "async-stream"]
 convert = ["zip"]
-convert_async = [
-    "futures",
-    "futures-core",
-    "futures-util",
-    "async-stream",
-    "async_zip",
-    "tokio",
-]
+convert_async = ["futures", "futures-core", "futures-util", "async-stream", "async_zip", "tokio"]
 
 [dependencies]
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
-bincode = "^2.0.0-rc.2"
 zip = { version = "0.6", optional = true }
 async_zip = { version = "0.0.15" , features = [
     "zstd",
@@ -70,6 +46,9 @@ async-stream = { version = "0.3", optional = true }
 zstd = { version = "^0.12", default-features = false, optional = true }
 memmap = { version = "0.7.0", optional = true }
 pin-project = { version = "1.1.3", optional = true }
+postcard = { version = "1.0.6", default-features = false }
+bitflags = "2.4.0"
+bstringify = "0.1.2"
 
 [dev-dependencies]
 insta = { version = "1.31.0", features = ["yaml"] }

lib/src/async_db.rs

@@ -24,9 +24,9 @@ use fmmap::tokio::{AsyncMmapFile, AsyncMmapFileExt, AsyncOptions};
 
 type LSize = u32;
 const LEN_SIZE: usize = std::mem::size_of::<LSize>();
-const BINCODE_CFG: bincode::config::Configuration = bincode::config::standard();
 
-use crate::util::BincodeVecWriter;
+use serde::{de::DeserializeOwned, Serialize};
+
 use crate::util::ErrorToString;
 
 pub struct WriterOpts {
@@ -42,18 +42,18 @@ impl Default for WriterOpts {
             compress_lvl: Level::Default,
             data_buf_size: 500 * 1024 * 1024,
             out_buf_size: 200 * 1024 * 1024,
-            current_buf_size: 100 * 1024,
+            current_buf_size: 1024 * 1024,
         }
     }
 }
 
 pub struct Writer<T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     out: io::BufWriter<fs::File>,
     data_buf: Vec<u8>,
-    cur_buf_item: BincodeVecWriter,
+    cur_buf_item: Vec<u8>,
     table: Vec<LSize>,
     compress_lvl: Level,
     _t: PhantomData<Arc<T>>,
@@ -61,14 +61,13 @@ where
 
 impl<T> Writer<T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     pub async fn new<P: AsRef<Path>>(path: P, opts: WriterOpts) -> Result<Self, String> {
         let out = fs::File::create(path).await.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_item: Vec<u8> = Vec::with_capacity(opts.current_buf_size);
-        let cur_buf_item = BincodeVecWriter::new(cur_buf_item);
+        let cur_buf_item: Vec<u8> = vec![0; opts.current_buf_size];
 
         let compress_lvl = opts.compress_lvl;
 
@@ -88,16 +87,16 @@ where
         self.push_by_ref(&item).await
     }
 
+    #[allow(clippy::useless_asref)]
     pub async fn push_by_ref(&mut self, item: &T) -> Result<(), String> {
         let pos: LSize = self.data_buf.len() as LSize;
+        let cur_item_data = postcard::to_slice(item, self.cur_buf_item.as_mut_slice()).str_err()?;
 
-        bincode::encode_into_writer(item, &mut self.cur_buf_item, BINCODE_CFG).str_err()?;
-
-        let mut zencoder = ZstdEncoder::with_quality(&self.cur_buf_item[..], self.compress_lvl);
+        let mut zencoder = ZstdEncoder::with_quality(cur_item_data.as_ref(), self.compress_lvl);
         io::copy(&mut zencoder, &mut self.data_buf)
             .await
             .str_err()?;
-        self.cur_buf_item.clear();
+        cur_item_data.fill(0);
 
         self.table.push(pos);
 
@@ -159,7 +158,7 @@ use pin_project::pin_project;
 /// only work when ..push.poll() returns Ready immediately
 pub struct WriterSink<'a, T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     #[pin]
     writer: &'a mut Writer<T>,
@@ -168,7 +167,7 @@ where
 
 impl<'a, T> Sink<T> for WriterSink<'a, T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     type Error = String;
 
@@ -213,7 +212,7 @@ where
 
 pub struct Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     mmap: AsyncMmapFile,
     count: usize,
@@ -223,7 +222,7 @@ where
 
 impl<T> Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     pub async fn new<P: AsRef<Path>>(path: P) -> Result<Self, String> {
         let mmap = AsyncOptions::new()
@@ -292,10 +291,10 @@ where
         decoder.read_to_end(data_buf).await.str_err()?;
 
         // decode item
-        let item: (T, usize) = bincode::decode_from_slice(data_buf, BINCODE_CFG).str_err()?;
+        let (item, _): (T, _) = postcard::take_from_bytes(data_buf).str_err()?;
 
         data_buf.clear();
-        Ok(item.0)
+        Ok(item)
     }
 
     /// get item at index
@@ -311,7 +310,7 @@ where
 
 pub struct ReaderStream<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     reader: &'a Reader<T>,
     index: Option<usize>,
@@ -319,7 +318,7 @@ where
 
 impl<'a, T> ReaderStream<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn new(reader: &'a Reader<T>) -> Self {
         ReaderStream {
@@ -331,7 +330,7 @@ where
 
 impl<'a, T> Stream for ReaderStream<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Item = T;
 
@@ -375,7 +374,7 @@ where
 
 pub struct BufReader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     inner: Reader<T>,
     buf: Vec<u8>,
@@ -383,7 +382,7 @@ where
 
 impl<T> BufReader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     pub async fn new<P: AsRef<Path>>(path: P, buf_size: usize) -> Result<Self, String> {
         match Reader::<T>::new(path).await {
@@ -410,7 +409,7 @@ where
 
 impl<T> From<Reader<T>> for BufReader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn from(inner: Reader<T>) -> Self {
         Self {
@@ -422,7 +421,7 @@ where
 
 impl<T> From<BufReader<T>> for Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn from(value: BufReader<T>) -> Self {
         value.into_inner()
@@ -431,7 +430,7 @@ where
 
 impl<T> Deref for BufReader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Target = Reader<T>;
     fn deref(&self) -> &Self::Target {
@@ -441,7 +440,7 @@ where
 
 pub struct BufReaderStream<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     reader: BufReader<T>,
     index: Option<usize>,
@@ -449,7 +448,7 @@ where
 
 impl<T> BufReaderStream<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn new(reader: BufReader<T>) -> Self {
         BufReaderStream {
@@ -473,7 +472,7 @@ where
 
 impl<T> Stream for BufReaderStream<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Item = T;
 
@@ -516,9 +515,10 @@ where
 mod test {
     use super::*;
     use core::fmt::Debug;
+    use serde_derive::Deserialize;
     use tempfile::tempdir;
 
-    #[derive(bincode::Encode, bincode::Decode, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+    #[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
     struct TestData {
         num: u64,
         test: String,

lib/src/db.rs

@@ -6,13 +6,13 @@ use std::{
     sync::Arc,
 };
 
+use serde::{de::DeserializeOwned, Serialize};
+
 use memmap::{Mmap, MmapOptions};
 
 type LSize = u32;
 const LEN_SIZE: usize = std::mem::size_of::<LSize>();
-const BINCODE_CFG: bincode::config::Configuration = bincode::config::standard();
 
-use crate::util::BincodeVecWriter;
 use crate::util::ErrorToString;
 
 pub struct WriterOpts {
@@ -28,19 +28,19 @@ impl Default for WriterOpts {
             compress_lvl: 1,
             data_buf_size: 500 * 1024 * 1024,
             out_buf_size: 200 * 1024 * 1024,
-            current_buf_size: 100 * 1024,
+            current_buf_size: 20 * 1024,
         }
     }
 }
 
 pub struct Writer<T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     out: io::BufWriter<fs::File>,
     data_buf: Cursor<Vec<u8>>,
     cur_buf_raw: Cursor<Vec<u8>>,
-    cur_buf_item: BincodeVecWriter,
+    cur_buf_item: Vec<u8>,
     table: Vec<LSize>,
     compress_lvl: i32,
     _t: PhantomData<Arc<T>>,
@@ -48,7 +48,7 @@ where
 
 impl<T> Writer<T>
 where
-    T: bincode::Encode,
+    T: Serialize,
 {
     pub fn new<P: AsRef<Path>>(path: P, opts: WriterOpts) -> Result<Self, String> {
         let out = fs::File::create(path).str_err()?;
@@ -58,8 +58,7 @@ where
 
         let cur_buf_raw: Vec<u8> = Vec::with_capacity(opts.current_buf_size);
         let cur_buf_raw = Cursor::new(cur_buf_raw);
-        let cur_buf_item: Vec<u8> = Vec::with_capacity(opts.current_buf_size);
-        let cur_buf_item = BincodeVecWriter::new(cur_buf_item);
+        let cur_buf_item: Vec<u8> = vec![0; opts.current_buf_size];
 
         let compress_lvl = opts.compress_lvl;
 
@@ -83,19 +82,20 @@ where
     pub fn push_by_ref(&mut self, item: &T) -> Result<(), String> {
         let pos: LSize = self.data_buf.position() as LSize;
 
-        bincode::encode_into_writer(item, &mut self.cur_buf_item, BINCODE_CFG).str_err()?;
+        let cur_item_data = postcard::to_slice(item, self.cur_buf_item.as_mut_slice()).str_err()?;
 
         let mut zencoder = zstd::stream::raw::Encoder::new(self.compress_lvl).str_err()?;
         zencoder
-            .set_pledged_src_size(Some(self.cur_buf_item.len() as u64))
+            .set_pledged_src_size(Some(cur_item_data.len() as u64))
             .str_err()?;
 
         self.cur_buf_raw.set_position(0);
         let mut cur_buf_z = zstd::stream::zio::Writer::new(&mut self.cur_buf_raw, zencoder);
-        cur_buf_z.write_all(&self.cur_buf_item).str_err()?;
+        cur_buf_z.write_all(cur_item_data).str_err()?;
         cur_buf_z.finish().str_err()?;
         cur_buf_z.flush().str_err()?;
-        self.cur_buf_item.clear();
+
+        cur_item_data.fill(0);
 
         self.table.push(pos);
         let (cur_buf_raw, _) = cur_buf_z.into_inner();
@@ -150,7 +150,7 @@ where
 
 pub struct Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     mmap: Mmap,
     count: usize,
@@ -160,7 +160,7 @@ where
 
 impl<T> Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     pub fn new<P: AsRef<Path>>(path: P, _buf_size: usize) -> Result<Self, String> {
         let file = fs::File::open(path).str_err()?;
@@ -215,9 +215,9 @@ where
         let data = zstd::decode_all(reader).str_err()?;
 
         // decode item
-        let item: (T, usize) = bincode::decode_from_slice(&data, BINCODE_CFG).str_err()?;
+        let (item, _): (T, _) = postcard::take_from_bytes(&data).str_err()?;
 
-        Ok(item.0)
+        Ok(item)
     }
 
     pub fn iter(&self) -> ReaderIter<'_, T> {
@@ -227,7 +227,7 @@ where
 
 pub struct ReaderIter<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     reader: &'a Reader<T>,
     index: Option<usize>,
@@ -235,7 +235,7 @@ where
 
 impl<'a, T> ReaderIter<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn new(reader: &'a Reader<T>) -> Self {
         ReaderIter {
@@ -247,7 +247,7 @@ where
 
 impl<'a, T> Iterator for ReaderIter<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Item = T;
 
@@ -300,7 +300,7 @@ where
 
 impl<'a, T> ExactSizeIterator for ReaderIter<'a, T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn len(&self) -> usize {
         self.reader.len()
@@ -309,7 +309,7 @@ where
 
 pub struct ReaderIntoIter<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     reader: Reader<T>,
     index: Option<usize>,
@@ -317,7 +317,7 @@ where
 
 impl<T> ReaderIntoIter<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn new(reader: Reader<T>) -> Self {
         Self {
@@ -329,7 +329,7 @@ where
 
 impl<T> Iterator for ReaderIntoIter<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Item = T;
 
@@ -382,7 +382,7 @@ where
 
 impl<T> ExactSizeIterator for ReaderIntoIter<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     fn len(&self) -> usize {
         self.reader.len()
@@ -391,7 +391,7 @@ where
 
 impl<T> IntoIterator for Reader<T>
 where
-    T: bincode::Decode,
+    T: DeserializeOwned,
 {
     type Item = T;
     type IntoIter = ReaderIntoIter<Self::Item>;
@@ -404,9 +404,10 @@ where
 #[cfg(test)]
 mod test {
     use super::*;
+    use serde::Deserialize;
     use tempfile::tempdir;
 
-    #[derive(bincode::Encode, bincode::Decode, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+    #[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
     struct TestData {
         num: u64,
         test: String,
@@ -427,7 +428,7 @@ mod test {
             compress_lvl: 1,
             data_buf_size: 10 * 1024 * 1024,
             out_buf_size: 10 * 1024 * 1024,
-            current_buf_size: 4096,
+            current_buf_size: 20 * 1024,
         };
         let mut writer: Writer<TestData> = Writer::new(&tmpfile, opts).expect("new writer");
 
@@ -454,7 +455,7 @@ mod test {
             compress_lvl: 1,
             data_buf_size: 10 * 1024 * 1024,
             out_buf_size: 10 * 1024 * 1024,
-            current_buf_size: 4096,
+            current_buf_size: 20 * 1024,
         };
         let mut writer: Writer<TestData> = Writer::new(&tmpfile, opts).expect("new writer");
 
@@ -480,7 +481,7 @@ mod test {
             compress_lvl: 1,
             data_buf_size: 10 * 1024 * 1024,
             out_buf_size: 10 * 1024 * 1024,
-            current_buf_size: 4096,
+            current_buf_size: 20 * 1024,
         };
         let mut writer: Writer<TestData> = Writer::new(&tmpfile, opts).expect("new writer");
 
@@ -509,7 +510,7 @@ mod test {
             compress_lvl: 1,
             data_buf_size: 10 * 1024 * 1024,
             out_buf_size: 10 * 1024 * 1024,
-            current_buf_size: 4096,
+            current_buf_size: 20 * 1024,
         };
         let mut writer: Writer<TestData> = Writer::new(&tmpfile, opts).expect("new writer");
 

lib/src/questions.rs

@@ -1,88 +1,800 @@
-use serde_derive::{Deserialize, Serialize};
+use std::{
+    fmt::{self, Formatter},
+    marker::PhantomData,
+};
 
-#[derive(
-    Debug, Default, Clone, Serialize, Deserialize, bincode::Decode, bincode::Encode, PartialEq,
-)]
+use serde::{
+    de::{MapAccess, SeqAccess, Visitor},
+    Deserialize, Deserializer,
+};
+
+use bstringify::bstringify;
+use serde::ser::SerializeStruct;
+
+use bitflags::bitflags;
+
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct BatchFlags: u16 {
+        const FILENAME = 1;
+        const DESCRIPTION = 1 << 1;
+        const AUTHOR = 1 << 2;
+        const COMMENT = 1 << 3;
+        const URL = 1 << 4;
+        const DATE = 1 << 5;
+        const PROCESSED = 1 << 6;
+        const REDACTED = 1 << 7;
+        const COPYRIGHT = 1 << 8;
+        const THEME = 1 << 9;
+        const KIND = 1 << 10;
+        const SOURCE = 1 << 11;
+        const RATING = 1 << 12;
+    }
+}
+
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct QuestionFlags: u16 {
+        const NUM = 1;
+        const AUTHOR = 1 << 1;
+        const COMMENT = 1 << 2;
+        const COMMENT1 = 1 << 3;
+        const TOUR = 1 << 4;
+        const URL = 1 << 5;
+        const DATE = 1 << 6;
+        const PROCESSED_BY = 1 << 7;
+        const REDACTED_BY = 1 << 8;
+        const COPYRIGHT = 1 << 9;
+        const THEME = 1 << 10;
+        const KIND = 1 << 11;
+        const SOURCE = 1 << 12;
+        const RATING = 1 << 13;
+        const BATCH_INFO = 1 << 14;
+    }
+}
+
+#[derive(Debug, Default, Clone, PartialEq)]
 pub struct BatchInfo {
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub filename: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub description: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub author: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub comment: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub url: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub date: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub processed_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub redacted_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub copyright: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub theme: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub kind: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub source: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub rating: String,
 }
 
-#[derive(
-    Debug, Default, Clone, Serialize, Deserialize, bincode::Decode, bincode::Encode, PartialEq,
-)]
+#[derive(Debug, Default, Clone, PartialEq)]
 pub struct Question {
-    #[serde(default, skip_serializing_if = "u32_is_zero")]
     pub num: u32,
-    pub id: String,
 
+    // required fields
+    pub id: String,
     pub description: String,
     pub answer: String,
 
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub author: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub comment: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub comment1: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub tour: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub url: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub date: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub processed_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub redacted_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub copyright: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub theme: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub kind: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub source: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub rating: String,
-    #[serde(default, skip_serializing_if = "BatchInfo::is_default")]
     pub batch_info: BatchInfo,
 }
 
-fn u32_is_zero(num: &u32) -> bool {
-    *num == 0
-}
-
 impl BatchInfo {
     pub fn is_default(&self) -> bool {
         *self == BatchInfo::default()
     }
 }
 
+/// fill flags, if string field is not empty set bit flag
+///
+/// Example:
+/// ```ignore
+/// flags_from_strings!((self, flags, BatchFlags) <- { filename: FILENAME, description: DESCRIPTION, ... });
+/// ```
+macro_rules! flags_from_strings {
+    (($self:ident, $flags:ident, $FlagsType:ident) <- {$($field:ident:$flag:ident),+} ) => {$(
+        if !$self.$field.is_empty() {
+            $flags |= $FlagsType::$flag;
+        }
+    )+}
+}
+
+/// serialize fields, if bit flag is not set then skip
+///
+/// Example:
+/// ```ignore
+/// serialize_fields!((self, flags, state, BatchFlags) <- { filename: FILENAME, description: DESCRIPTION, ... });
+/// ```
+macro_rules! serialize_fields {
+    (($self:ident, $flags:ident, $state:ident, $FlagsType:ident) <- {$($field:ident:$flag:ident),+} ) => {$(
+        if $flags.intersects($FlagsType::$flag) {
+            $state.serialize_field(std::stringify!($field), &$self.$field)?;
+        } else {
+            $state.skip_field(std::stringify!($field))?;
+        }
+    )+}
+}
+
+impl serde::Serialize for BatchInfo {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let is_human_readable = serializer.is_human_readable();
+        let mut flags: BatchFlags = Default::default();
+        let len = 13;
+
+        flags_from_strings!((self, flags, BatchFlags) <- {
+            filename: FILENAME, description: DESCRIPTION, author: AUTHOR, comment: COMMENT, url: URL, date: DATE, processed_by: PROCESSED,
+            redacted_by: REDACTED, copyright: COPYRIGHT, theme: THEME, kind: KIND, source: SOURCE, rating: RATING
+        });
+
+        let mut state = serializer.serialize_struct("BatchInfo", len)?;
+
+        if is_human_readable {
+            state.skip_field("_flags")?;
+        } else {
+            state.serialize_field("_flags", &flags.bits())?;
+        }
+
+        serialize_fields!((self, flags, state, BatchFlags) <- {
+            filename: FILENAME, description: DESCRIPTION, author: AUTHOR, comment: COMMENT, url: URL, date: DATE, processed_by: PROCESSED,
+            redacted_by: REDACTED, copyright: COPYRIGHT, theme: THEME, kind: KIND, source: SOURCE, rating: RATING
+        });
+
+        state.end()
+    }
+}
+
+impl serde::Serialize for Question {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let is_human_readable = serializer.is_human_readable();
+        let mut flags: QuestionFlags = Default::default();
+        let len = 19;
+
+        if self.num != 0 {
+            flags |= QuestionFlags::NUM;
+        }
+
+        if !self.batch_info.is_default() {
+            flags |= QuestionFlags::BATCH_INFO;
+        }
+
+        flags_from_strings!((self, flags, QuestionFlags) <- {
+            author: AUTHOR, comment: COMMENT, comment1: COMMENT1, tour: TOUR, url: URL, date: DATE,
+            processed_by: PROCESSED_BY, redacted_by: REDACTED_BY, copyright: COPYRIGHT, theme: THEME,
+            kind: KIND, source: SOURCE, rating: RATING
+        });
+
+        let mut state = serializer.serialize_struct("Question", len)?;
+
+        if is_human_readable {
+            state.skip_field("_flags")?;
+        } else {
+            state.serialize_field("_flags", &flags.bits())?;
+        }
+
+        if flags.intersects(QuestionFlags::NUM) {
+            state.serialize_field("num", &self.num)?;
+        } else {
+            state.skip_field("num")?;
+        }
+
+        state.serialize_field("id", &self.id)?;
+        state.serialize_field("description", &self.description)?;
+        state.serialize_field("answer", &self.answer)?;
+
+        serialize_fields!((self, flags, state, QuestionFlags) <- {
+            author: AUTHOR, comment: COMMENT, comment1: COMMENT1, tour: TOUR, url: URL, date: DATE,
+            processed_by: PROCESSED_BY, redacted_by: REDACTED_BY, copyright: COPYRIGHT, theme: THEME,
+            kind: KIND, source: SOURCE, rating: RATING, batch_info: BATCH_INFO
+        });
+
+        if flags.intersects(QuestionFlags::BATCH_INFO) {
+            state.serialize_field("batch_info", &self.batch_info)?;
+        } else {
+            state.skip_field("batch_info")?;
+        }
+
+        state.end()
+    }
+}
+
+/// match field name on _FieldVisitor::visit_str or ::visit_bytes
+///
+/// Examples:
+///
+/// str:
+/// ```ignore
+/// fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+/// where E: serde::de::Error, {
+///     match_visit_str_fields!(value => BatchField {filename, description, ...})
+/// }
+/// ```
+///
+/// or bytes:
+/// ```ignore
+/// fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
+/// where E: serde::de::Error, {
+///     match_visit_str_fields!([bytes] value => BatchField {filename, description, ...})
+/// }
+/// ```
+macro_rules! match_visit_str_fields {
+    ($value:ident => $FieldType:ty {$($field:ident),+}) => {
+        match $value {
+        $(
+            std::stringify!($field) => Ok(<$FieldType>::$field),
+        )+
+        _ => Ok(<$FieldType>::__ignore),
+      }
+   };
+   ([bytes] $value:ident => $FieldType:ty {$($field:ident),+}) => {
+    match $value {
+    $(
+        bstringify!($field) => Ok(<$FieldType>::$field),
+    )+
+    _ => Ok(<$FieldType>::__ignore),
+  }
+}
+}
+
+/// for seq access, deserialize string fields if bit flag is set, else read as default (empty)
+macro_rules! seq_read_strings {
+    (($flags:ident, $seq:ident, $FlagsType:ty) <- {$($field:ident:$flag:ident),+} ) => {$(
+        let $field: String = if $flags.intersects(<$FlagsType>::$flag) {
+            SeqAccess::next_element::<String>(&mut $seq)?.unwrap_or_default()
+        } else {
+            Default::default()
+        };
+    )+}
+}
+
+/// for map access, match and deserialize fields + check for duplicated fields
+///
+/// Examples:
+///
+/// variant for mixed value types:
+/// ```ignore
+/// match_map_fields!((map, key, QuestionField) <- {num: u32, id: String, ...});
+/// ```
+///
+/// variant for single value type:
+/// ```ignore
+/// match_map_fields!((map, key, BatchField, String) <- {filename, url, ...});
+/// ```
+macro_rules! match_map_fields {
+    (($map:ident, $key:ident, $FieldType:ty) <- {$($field:ident:$FieldValueType:ty),+} ) => {
+        match $key {
+        $(
+            <$FieldType>::$field => {
+                if $field.is_some() {
+                    return Err(<V::Error as serde::de::Error>::duplicate_field(
+                        std::stringify!($field),
+                    ));
+                }
+                $field = Some(MapAccess::next_value::<$FieldValueType>(&mut $map)?);
+            },
+        )+
+        _ => {
+            let _ = MapAccess::next_value::<serde::de::IgnoredAny>(&mut $map)?;
+        }
+      }
+  };
+  (($map:ident, $key:ident, $FieldType:ty, $FieldValueType:ty) <- {$($field:ident),+} ) => {
+    match $key {
+    $(
+        <$FieldType>::$field => {
+            if $field.is_some() {
+                return Err(<V::Error as serde::de::Error>::duplicate_field(
+                    std::stringify!($field),
+                ));
+            }
+            $field = Some(MapAccess::next_value::<$FieldValueType>(&mut $map)?);
+        },
+    )+
+    _ => {
+        let _ = MapAccess::next_value::<serde::de::IgnoredAny>(&mut $map)?;
+    }
+  }
+}
+}
+
+impl<'de> Deserialize<'de> for BatchInfo {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[allow(non_camel_case_types)]
+        enum BatchField {
+            filename,
+            description,
+            author,
+            comment,
+            url,
+            date,
+            processed_by,
+            redacted_by,
+            copyright,
+            theme,
+            kind,
+            source,
+            rating,
+            _flags,
+            __ignore,
+        }
+
+        struct BatchFieldVisitor;
+        impl<'de> Visitor<'de> for BatchFieldVisitor {
+            type Value = BatchField;
+            fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                Formatter::write_str(formatter, "field identifier")
+            }
+            fn visit_u64<E>(self, value: u64) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match value {
+                    0u64 => Ok(BatchField::filename),
+                    1u64 => Ok(BatchField::description),
+                    2u64 => Ok(BatchField::author),
+                    3u64 => Ok(BatchField::comment),
+                    4u64 => Ok(BatchField::url),
+                    5u64 => Ok(BatchField::date),
+                    6u64 => Ok(BatchField::processed_by),
+                    7u64 => Ok(BatchField::redacted_by),
+                    8u64 => Ok(BatchField::copyright),
+                    9u64 => Ok(BatchField::theme),
+                    10u64 => Ok(BatchField::kind),
+                    11u64 => Ok(BatchField::source),
+                    12u64 => Ok(BatchField::rating),
+                    13u64 => Ok(BatchField::_flags),
+                    _ => Ok(BatchField::__ignore),
+                }
+            }
+            fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match_visit_str_fields!(value => BatchField {
+                    filename, description, author, comment, url, date, processed_by, redacted_by,
+                    copyright, theme, kind, source, rating, _flags, __ignore
+                })
+            }
+            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match_visit_str_fields!([bytes] value => BatchField {
+                    filename, description, author, comment, url, date, processed_by, redacted_by,
+                    copyright, theme, kind, source, rating, _flags, __ignore
+                })
+            }
+        }
+        impl<'de> Deserialize<'de> for BatchField {
+            #[inline]
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                Deserializer::deserialize_identifier(deserializer, BatchFieldVisitor)
+            }
+        }
+        struct BatchInfoVisitor<'de> {
+            marker: PhantomData<BatchInfo>,
+            lifetime: PhantomData<&'de ()>,
+        }
+        impl<'de> Visitor<'de> for BatchInfoVisitor<'de> {
+            type Value = BatchInfo;
+            fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                Formatter::write_str(formatter, "struct BatchInfo")
+            }
+            #[inline]
+            fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
+            where
+                V: SeqAccess<'de>,
+            {
+                let flags = BatchFlags::from_bits(
+                    SeqAccess::next_element::<u16>(&mut seq)?.unwrap_or_default(),
+                )
+                .unwrap_or_default();
+
+                seq_read_strings!((flags, seq, BatchFlags) <- {
+                    filename: FILENAME, description: DESCRIPTION, author: AUTHOR, comment: COMMENT, url: URL, date: DATE, processed_by: PROCESSED,
+                    redacted_by: REDACTED, copyright: COPYRIGHT, theme: THEME, kind: KIND, source: SOURCE, rating: RATING
+                });
+
+                Ok(BatchInfo {
+                    filename,
+                    description,
+                    author,
+                    comment,
+                    url,
+                    date,
+                    processed_by,
+                    redacted_by,
+                    copyright,
+                    theme,
+                    kind,
+                    source,
+                    rating,
+                })
+            }
+            #[inline]
+            fn visit_map<V>(self, mut map: V) -> Result<Self::Value, V::Error>
+            where
+                V: MapAccess<'de>,
+            {
+                let mut filename: Option<String> = None;
+                let mut description: Option<String> = None;
+                let mut author: Option<String> = None;
+                let mut comment: Option<String> = None;
+                let mut url: Option<String> = None;
+                let mut date: Option<String> = None;
+                let mut processed_by: Option<String> = None;
+                let mut redacted_by: Option<String> = None;
+                let mut copyright: Option<String> = None;
+                let mut theme: Option<String> = None;
+                let mut kind: Option<String> = None;
+                let mut source: Option<String> = None;
+                let mut rating: Option<String> = None;
+
+                while let Some(key) = MapAccess::next_key::<BatchField>(&mut map)? {
+                    match_map_fields!((map, key, BatchField, String) <- {
+                        filename, description, author, comment, url, date, processed_by,
+                        redacted_by, copyright, theme, kind, source, rating
+                    });
+                }
+
+                let filename = filename.unwrap_or_default();
+                let description = description.unwrap_or_default();
+                let author = author.unwrap_or_default();
+                let comment = comment.unwrap_or_default();
+                let url = url.unwrap_or_default();
+                let date = date.unwrap_or_default();
+                let processed_by = processed_by.unwrap_or_default();
+                let redacted_by = redacted_by.unwrap_or_default();
+                let copyright = copyright.unwrap_or_default();
+                let theme = theme.unwrap_or_default();
+                let kind = kind.unwrap_or_default();
+                let source = source.unwrap_or_default();
+                let rating = rating.unwrap_or_default();
+
+                Ok(BatchInfo {
+                    filename,
+                    description,
+                    author,
+                    comment,
+                    url,
+                    date,
+                    processed_by,
+                    redacted_by,
+                    copyright,
+                    theme,
+                    kind,
+                    source,
+                    rating,
+                })
+            }
+        }
+        const FIELDS: &[&str] = &[
+            "filename",
+            "description",
+            "author",
+            "comment",
+            "url",
+            "date",
+            "processed_by",
+            "redacted_by",
+            "copyright",
+            "theme",
+            "kind",
+            "source",
+            "rating",
+        ];
+        Deserializer::deserialize_struct(
+            deserializer,
+            "BatchInfo",
+            FIELDS,
+            BatchInfoVisitor {
+                marker: PhantomData::<BatchInfo>,
+                lifetime: PhantomData,
+            },
+        )
+    }
+}
+
+impl<'de> Deserialize<'de> for Question {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[allow(non_camel_case_types)]
+        enum QuestionField {
+            num,
+            id,
+            description,
+            answer,
+            author,
+            comment,
+            comment1,
+            tour,
+            url,
+            date,
+            processed_by,
+            redacted_by,
+            copyright,
+            theme,
+            kind,
+            source,
+            rating,
+            batch_info,
+            _flags,
+            __ignore,
+        }
+
+        struct QuestionFieldVisitor;
+        impl<'de> Visitor<'de> for QuestionFieldVisitor {
+            type Value = QuestionField;
+            fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                Formatter::write_str(formatter, "field identifier")
+            }
+            fn visit_u64<E>(self, value: u64) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match value {
+                    0u64 => Ok(QuestionField::num),
+                    1u64 => Ok(QuestionField::id),
+                    2u64 => Ok(QuestionField::description),
+                    3u64 => Ok(QuestionField::answer),
+                    4u64 => Ok(QuestionField::author),
+                    5u64 => Ok(QuestionField::comment),
+                    6u64 => Ok(QuestionField::comment1),
+                    7u64 => Ok(QuestionField::tour),
+                    8u64 => Ok(QuestionField::url),
+                    9u64 => Ok(QuestionField::date),
+                    10u64 => Ok(QuestionField::processed_by),
+                    11u64 => Ok(QuestionField::redacted_by),
+                    12u64 => Ok(QuestionField::copyright),
+                    13u64 => Ok(QuestionField::theme),
+                    14u64 => Ok(QuestionField::kind),
+                    15u64 => Ok(QuestionField::source),
+                    16u64 => Ok(QuestionField::rating),
+                    17u64 => Ok(QuestionField::batch_info),
+                    18u64 => Ok(QuestionField::_flags),
+                    _ => Ok(QuestionField::__ignore),
+                }
+            }
+            fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match_visit_str_fields!(value => QuestionField {
+                    num, id, description, answer, author, comment, comment1, tour, url, date, processed_by,
+                    redacted_by, copyright, theme, kind, source, rating, batch_info, _flags, __ignore
+                })
+            }
+            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match_visit_str_fields!([bytes] value => QuestionField {
+                    num, id, description, answer, author, comment, comment1, tour, url, date, processed_by,
+                    redacted_by, copyright, theme, kind, source, rating, batch_info, _flags, __ignore
+                })
+            }
+        }
+        impl<'de> Deserialize<'de> for QuestionField {
+            #[inline]
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                Deserializer::deserialize_identifier(deserializer, QuestionFieldVisitor)
+            }
+        }
+        #[doc(hidden)]
+        struct QuestionVisitor<'de> {
+            marker: PhantomData<Question>,
+            lifetime: PhantomData<&'de ()>,
+        }
+        impl<'de> Visitor<'de> for QuestionVisitor<'de> {
+            type Value = Question;
+            fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
+                Formatter::write_str(formatter, "struct Question")
+            }
+            #[inline]
+            fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
+            where
+                V: SeqAccess<'de>,
+            {
+                let _flags = QuestionFlags::from_bits(
+                    SeqAccess::next_element::<u16>(&mut seq)?.unwrap_or_default(),
+                )
+                .unwrap_or_default();
+
+                let num: u32 = if _flags.intersects(QuestionFlags::NUM) {
+                    SeqAccess::next_element::<u32>(&mut seq)?.unwrap_or_default()
+                } else {
+                    Default::default()
+                };
+
+                let id = match SeqAccess::next_element::<String>(&mut seq)? {
+                    Some(value) => value,
+                    _ => return Err(<V::Error as serde::de::Error>::missing_field("id")),
+                };
+                let description = match SeqAccess::next_element::<String>(&mut seq)? {
+                    Some(value) => value,
+                    _ => return Err(<V::Error as serde::de::Error>::missing_field("description")),
+                };
+                let answer = match SeqAccess::next_element::<String>(&mut seq)? {
+                    Some(value) => value,
+                    _ => return Err(<V::Error as serde::de::Error>::missing_field("answer")),
+                };
+
+                seq_read_strings!((_flags, seq, QuestionFlags) <- {
+                    author: AUTHOR, comment: COMMENT, comment1: COMMENT1, tour: TOUR, url: URL, date: DATE,
+                    processed_by: PROCESSED_BY, redacted_by: REDACTED_BY, copyright: COPYRIGHT, theme: THEME,
+                    kind: KIND, source: SOURCE, rating: RATING
+                });
+
+                let batch_info: BatchInfo = if _flags.intersects(QuestionFlags::BATCH_INFO) {
+                    SeqAccess::next_element::<BatchInfo>(&mut seq)?.unwrap_or_default()
+                } else {
+                    Default::default()
+                };
+
+                Ok(Question {
+                    num,
+                    id,
+                    description,
+                    answer,
+                    author,
+                    comment,
+                    comment1,
+                    tour,
+                    url,
+                    date,
+                    processed_by,
+                    redacted_by,
+                    copyright,
+                    theme,
+                    kind,
+                    source,
+                    rating,
+                    batch_info,
+                })
+            }
+            #[inline]
+            fn visit_map<V>(self, mut map: V) -> Result<Self::Value, V::Error>
+            where
+                V: MapAccess<'de>,
+            {
+                let mut num: Option<u32> = None;
+                let mut id: Option<String> = None;
+                let mut description: Option<String> = None;
+                let mut answer: Option<String> = None;
+                let mut author: Option<String> = None;
+                let mut comment: Option<String> = None;
+                let mut comment1: Option<String> = None;
+                let mut tour: Option<String> = None;
+                let mut url: Option<String> = None;
+                let mut date: Option<String> = None;
+                let mut processed_by: Option<String> = None;
+                let mut redacted_by: Option<String> = None;
+                let mut copyright: Option<String> = None;
+                let mut theme: Option<String> = None;
+                let mut kind: Option<String> = None;
+                let mut source: Option<String> = None;
+                let mut rating: Option<String> = None;
+                let mut batch_info: Option<BatchInfo> = None;
+
+                while let Some(key) = MapAccess::next_key::<QuestionField>(&mut map)? {
+                    match_map_fields!((map, key, QuestionField) <- {
+                        num: u32, id: String, description: String, answer: String, author: String, comment: String,
+                        comment1: String, tour: String, url: String, date: String, processed_by: String, redacted_by: String,
+                        copyright: String, theme: String, kind: String, source: String, rating: String, batch_info: BatchInfo
+                    });
+                }
+
+                let id = id.ok_or(<V::Error as serde::de::Error>::missing_field("id"))?;
+                let description = description
+                    .ok_or(<V::Error as serde::de::Error>::missing_field("description"))?;
+                let answer =
+                    answer.ok_or(<V::Error as serde::de::Error>::missing_field("answer"))?;
+
+                let num = num.unwrap_or_default();
+                let author = author.unwrap_or_default();
+                let comment = comment.unwrap_or_default();
+                let comment1 = comment1.unwrap_or_default();
+                let tour = tour.unwrap_or_default();
+                let url = url.unwrap_or_default();
+                let date = date.unwrap_or_default();
+                let processed_by = processed_by.unwrap_or_default();
+                let redacted_by = redacted_by.unwrap_or_default();
+                let copyright = copyright.unwrap_or_default();
+                let theme = theme.unwrap_or_default();
+                let kind = kind.unwrap_or_default();
+                let source = source.unwrap_or_default();
+                let rating = rating.unwrap_or_default();
+                let batch_info = batch_info.unwrap_or_default();
+
+                Ok(Question {
+                    num,
+                    id,
+                    description,
+                    answer,
+                    author,
+                    comment,
+                    comment1,
+                    tour,
+                    url,
+                    date,
+                    processed_by,
+                    redacted_by,
+                    copyright,
+                    theme,
+                    kind,
+                    source,
+                    rating,
+                    batch_info,
+                })
+            }
+        }
+        #[doc(hidden)]
+        const FIELDS: &[&str] = &[
+            "num",
+            "id",
+            "description",
+            "answer",
+            "author",
+            "comment",
+            "comment1",
+            "tour",
+            "url",
+            "date",
+            "processed_by",
+            "redacted_by",
+            "copyright",
+            "theme",
+            "kind",
+            "source",
+            "rating",
+            "batch_info",
+        ];
+        Deserializer::deserialize_struct(
+            deserializer,
+            "Question",
+            FIELDS,
+            QuestionVisitor {
+                marker: PhantomData::<Question>,
+                lifetime: PhantomData,
+            },
+        )
+    }
+}
+
 #[cfg(any(feature = "convert", feature = "convert_async"))]
 pub mod convert_common {
     use super::{BatchInfo, Question};
@@ -372,6 +1084,18 @@ mod test {
             "#);
     }
     #[test]
+    fn test_question_serde_postcard() {
+        use postcard::{from_bytes, to_slice};
+
+        let original = sample_question();
+        let mut buff: Vec<u8> = vec![0; 135];
+
+        to_slice(&original, buff.as_mut_slice()).expect("to_slice");
+        let actual: Question = from_bytes(buff.as_slice()).expect("from_bytes");
+
+        assert_eq!(actual, original);
+    }
+    #[test]
     fn test_question_de() {
         let question_from_json: Result<Question, _> = serde_json::from_value(json!({
             "id": "Вопрос 1",

lib/src/util.rs

@@ -12,46 +12,3 @@ where
         self.map_err(|e| e.to_string())
     }
 }
-
-#[cfg(any(feature = "sync", feature = "async"))]
-mod bincode_utils {
-    use std::ops::{Deref, DerefMut};
-
-    use bincode::enc::write::Writer;
-    use bincode::error::EncodeError;
-
-    /// struct that allows [`Vec<u8>`] to implement [bincode::enc::write::Writer] trait
-    pub struct BincodeVecWriter {
-        vec: Vec<u8>,
-    }
-
-    impl BincodeVecWriter {
-        pub fn new(vec: Vec<u8>) -> BincodeVecWriter {
-            BincodeVecWriter { vec }
-        }
-    }
-
-    impl Deref for BincodeVecWriter {
-        type Target = Vec<u8>;
-
-        fn deref(&self) -> &Self::Target {
-            &self.vec
-        }
-    }
-
-    impl DerefMut for BincodeVecWriter {
-        fn deref_mut(&mut self) -> &mut Self::Target {
-            &mut self.vec
-        }
-    }
-
-    impl Writer for BincodeVecWriter {
-        fn write(&mut self, bytes: &[u8]) -> Result<(), EncodeError> {
-            self.vec.extend_from_slice(bytes);
-            Ok(())
-        }
-    }
-}
-
-#[cfg(any(feature = "sync", feature = "async"))]
-pub use bincode_utils::BincodeVecWriter;