Removing Deserializer trait

fastfield_codecs/benches/bench.rs

@@ -4,9 +4,9 @@ extern crate test;
 
 #[cfg(test)]
 mod tests {
-    use fastfield_codecs::bitpacked::{BitpackedReader, BitpackedSerializer};
-    use fastfield_codecs::blockwise_linear::{BlockwiseLinearReader, BlockwiseLinearSerializer};
-    use fastfield_codecs::linear::{LinearReader, LinearSerializer};
+    use fastfield_codecs::bitpacked::BitpackedCodec;
+    use fastfield_codecs::blockwise_linear::BlockwiseLinearCodec;
+    use fastfield_codecs::linear::LinearCodec;
     use fastfield_codecs::*;
 
     fn get_data() -> Vec<u64> {
@@ -25,24 +25,21 @@ mod tests {
     fn value_iter() -> impl Iterator<Item = u64> {
         0..20_000
     }
-    fn bench_get<S: FastFieldCodecSerializer, R: FastFieldCodecReader>(
-        b: &mut Bencher,
-        data: &[u64],
-    ) {
+    fn bench_get<Codec: FastFieldCodec>(b: &mut Bencher, data: &[u64]) {
         let mut bytes = vec![];
-        S::serialize(&mut bytes, &data).unwrap();
-        let reader = R::open_from_bytes(OwnedBytes::new(bytes)).unwrap();
+        Codec::serialize(&mut bytes, &data).unwrap();
+        let reader = Codec::open_from_bytes(OwnedBytes::new(bytes)).unwrap();
         b.iter(|| {
             let mut sum = 0u64;
             for pos in value_iter() {
-                let val = reader.get_u64(pos as u64);
+                let val = reader.get_val(pos as u64);
                 debug_assert_eq!(data[pos as usize], val);
                 sum = sum.wrapping_add(val);
             }
             sum
         });
     }
-    fn bench_create<S: FastFieldCodecSerializer>(b: &mut Bencher, data: &[u64]) {
+    fn bench_create<S: FastFieldCodec>(b: &mut Bencher, data: &[u64]) {
         let mut bytes = vec![];
         b.iter(|| {
             S::serialize(&mut bytes, &data).unwrap();
@@ -54,32 +51,32 @@ mod tests {
     #[bench]
     fn bench_fastfield_bitpack_create(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_create::<BitpackedSerializer>(b, &data);
+        bench_create::<BitpackedCodec>(b, &data);
     }
     #[bench]
     fn bench_fastfield_linearinterpol_create(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_create::<LinearSerializer>(b, &data);
+        bench_create::<LinearCodec>(b, &data);
     }
     #[bench]
     fn bench_fastfield_multilinearinterpol_create(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_create::<BlockwiseLinearSerializer>(b, &data);
+        bench_create::<BlockwiseLinearCodec>(b, &data);
     }
     #[bench]
     fn bench_fastfield_bitpack_get(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_get::<BitpackedSerializer, BitpackedReader>(b, &data);
+        bench_get::<BitpackedCodec>(b, &data);
     }
     #[bench]
     fn bench_fastfield_linearinterpol_get(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_get::<LinearSerializer, LinearReader>(b, &data);
+        bench_get::<LinearCodec>(b, &data);
     }
     #[bench]
     fn bench_fastfield_multilinearinterpol_get(b: &mut Bencher) {
         let data: Vec<_> = get_data();
-        bench_get::<BlockwiseLinearSerializer, BlockwiseLinearReader>(b, &data);
+        bench_get::<BlockwiseLinearCodec>(b, &data);
     }
     pub fn stats_from_vec(data: &[u64]) -> FastFieldStats {
         let min_value = data.iter().cloned().min().unwrap_or(0);

fastfield_codecs/src/bitpacked.rs

@@ -4,9 +4,7 @@ use common::BinarySerializable;
 use ownedbytes::OwnedBytes;
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
-use crate::{
-    FastFieldCodecReader, FastFieldCodecSerializer, FastFieldCodecType, FastFieldDataAccess,
-};
+use crate::{FastFieldCodec, FastFieldCodecType, FastFieldDataAccess};
 
 /// Depending on the field type, a different
 /// fast field is required.
@@ -14,29 +12,14 @@ use crate::{
 pub struct BitpackedReader {
     data: OwnedBytes,
     bit_unpacker: BitUnpacker,
-    pub min_value_u64: u64,
-    pub max_value_u64: u64,
+    min_value_u64: u64,
+    max_value_u64: u64,
+    num_vals: u64,
 }
 
-impl FastFieldCodecReader for BitpackedReader {
-    /// Opens a fast field given a file.
-    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self> {
-        let footer_offset = bytes.len() - 16;
-        let (data, mut footer) = bytes.split(footer_offset);
-        let min_value = u64::deserialize(&mut footer)?;
-        let amplitude = u64::deserialize(&mut footer)?;
-        let max_value = min_value + amplitude;
-        let num_bits = compute_num_bits(amplitude);
-        let bit_unpacker = BitUnpacker::new(num_bits);
-        Ok(BitpackedReader {
-            data,
-            min_value_u64: min_value,
-            max_value_u64: max_value,
-            bit_unpacker,
-        })
-    }
+impl FastFieldDataAccess for BitpackedReader {
     #[inline]
-    fn get_u64(&self, doc: u64) -> u64 {
+    fn get_val(&self, doc: u64) -> u64 {
         self.min_value_u64 + self.bit_unpacker.get(doc, &self.data)
     }
     #[inline]
@@ -47,11 +30,16 @@ impl FastFieldCodecReader for BitpackedReader {
     fn max_value(&self) -> u64 {
         self.max_value_u64
     }
+    #[inline]
+    fn num_vals(&self) -> u64 {
+        self.num_vals
+    }
 }
 pub struct BitpackedSerializerLegacy<'a, W: 'a + Write> {
     bit_packer: BitPacker,
     write: &'a mut W,
     min_value: u64,
+    num_vals: u64,
     amplitude: u64,
     num_bits: u8,
 }
@@ -78,6 +66,7 @@ impl<'a, W: Write> BitpackedSerializerLegacy<'a, W> {
             bit_packer,
             write,
             min_value,
+            num_vals: 0,
             amplitude,
             num_bits,
         })
@@ -88,22 +77,45 @@ impl<'a, W: Write> BitpackedSerializerLegacy<'a, W> {
         let val_to_write: u64 = val - self.min_value;
         self.bit_packer
             .write(val_to_write, self.num_bits, &mut self.write)?;
+        self.num_vals += 1;
         Ok(())
     }
     pub fn close_field(mut self) -> io::Result<()> {
         self.bit_packer.close(&mut self.write)?;
         self.min_value.serialize(&mut self.write)?;
         self.amplitude.serialize(&mut self.write)?;
+        self.num_vals.serialize(&mut self.write)?;
         Ok(())
     }
 }
 
-pub struct BitpackedSerializer {}
+pub struct BitpackedCodec;
 
-impl FastFieldCodecSerializer for BitpackedSerializer {
+impl FastFieldCodec for BitpackedCodec {
     /// The CODEC_TYPE is an enum value used for serialization.
     const CODEC_TYPE: FastFieldCodecType = FastFieldCodecType::Bitpacked;
 
+    type Reader = BitpackedReader;
+
+    /// Opens a fast field given a file.
+    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self::Reader> {
+        let footer_offset = bytes.len() - 24;
+        let (data, mut footer) = bytes.split(footer_offset);
+        let min_value = u64::deserialize(&mut footer)?;
+        let amplitude = u64::deserialize(&mut footer)?;
+        let num_vals = u64::deserialize(&mut footer)?;
+        let max_value = min_value + amplitude;
+        let num_bits = compute_num_bits(amplitude);
+        let bit_unpacker = BitUnpacker::new(num_bits);
+        Ok(BitpackedReader {
+            data,
+            bit_unpacker,
+            min_value_u64: min_value,
+            max_value_u64: max_value,
+            num_vals,
+        })
+    }
+
     /// Serializes data with the BitpackedFastFieldSerializer.
     ///
     /// The serializer in fact encode the values by bitpacking
@@ -146,7 +158,7 @@ mod tests {
     use crate::tests::get_codec_test_data_sets;
 
     fn create_and_validate(data: &[u64], name: &str) {
-        crate::tests::create_and_validate::<BitpackedSerializer, BitpackedReader>(data, name);
+        crate::tests::create_and_validate::<BitpackedCodec>(data, name);
     }
 
     #[test]

fastfield_codecs/src/blockwise_linear.rs

@@ -18,9 +18,7 @@ use ownedbytes::OwnedBytes;
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
 use crate::linear::{get_calculated_value, get_slope};
-use crate::{
-    FastFieldCodecReader, FastFieldCodecSerializer, FastFieldCodecType, FastFieldDataAccess,
-};
+use crate::{FastFieldCodec, FastFieldCodecType, FastFieldDataAccess};
 
 const CHUNK_SIZE: u64 = 512;
 
@@ -148,18 +146,9 @@ fn get_interpolation_function(doc: u64, interpolations: &[Function]) -> &Functio
     &interpolations[get_interpolation_position(doc)]
 }
 
-impl FastFieldCodecReader for BlockwiseLinearReader {
-    /// Opens a fast field given a file.
-    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self> {
-        let footer_len: u32 = (&bytes[bytes.len() - 4..]).deserialize()?;
-        let footer_offset = bytes.len() - 4 - footer_len as usize;
-        let (data, mut footer) = bytes.split(footer_offset);
-        let footer = BlockwiseLinearFooter::deserialize(&mut footer)?;
-        Ok(BlockwiseLinearReader { data, footer })
-    }
-
+impl FastFieldDataAccess for BlockwiseLinearReader {
     #[inline]
-    fn get_u64(&self, idx: u64) -> u64 {
+    fn get_val(&self, idx: u64) -> u64 {
         let interpolation = get_interpolation_function(idx, &self.footer.interpolations);
         let in_block_idx = idx - interpolation.start_pos;
         let calculated_value = get_calculated_value(
@@ -182,13 +171,29 @@ impl FastFieldCodecReader for BlockwiseLinearReader {
     fn max_value(&self) -> u64 {
         self.footer.max_value
     }
+    #[inline]
+    fn num_vals(&self) -> u64 {
+        self.footer.num_vals
+    }
 }
 
 /// Same as LinearSerializer, but working on chunks of CHUNK_SIZE elements.
-pub struct BlockwiseLinearSerializer {}
+pub struct BlockwiseLinearCodec;
 
-impl FastFieldCodecSerializer for BlockwiseLinearSerializer {
+impl FastFieldCodec for BlockwiseLinearCodec {
     const CODEC_TYPE: FastFieldCodecType = FastFieldCodecType::BlockwiseLinear;
+
+    type Reader = BlockwiseLinearReader;
+
+    /// Opens a fast field given a file.
+    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self::Reader> {
+        let footer_len: u32 = (&bytes[bytes.len() - 4..]).deserialize()?;
+        let footer_offset = bytes.len() - 4 - footer_len as usize;
+        let (data, mut footer) = bytes.split(footer_offset);
+        let footer = BlockwiseLinearFooter::deserialize(&mut footer)?;
+        Ok(BlockwiseLinearReader { data, footer })
+    }
+
     /// Creates a new fast field serializer.
     fn serialize(
         write: &mut impl Write,
@@ -363,9 +368,7 @@ mod tests {
     use crate::tests::get_codec_test_data_sets;
 
     fn create_and_validate(data: &[u64], name: &str) -> (f32, f32) {
-        crate::tests::create_and_validate::<BlockwiseLinearSerializer, BlockwiseLinearReader>(
-            data, name,
-        )
+        crate::tests::create_and_validate::<BlockwiseLinearCodec, BlockwiseLinearReader>(data, name)
     }
 
     const HIGHEST_BIT: u64 = 1 << 63;

fastfield_codecs/src/lib.rs

@@ -12,12 +12,15 @@ pub mod bitpacked;
 pub mod blockwise_linear;
 pub mod linear;
 
-pub trait FastFieldCodecReader: Sized {
-    /// reads the metadata and returns the CodecReader
-    fn open_from_bytes(bytes: OwnedBytes) -> std::io::Result<Self>;
-    fn get_u64(&self, doc: u64) -> u64;
+pub trait FastFieldDataAccess {
+    fn get_val(&self, doc: u64) -> u64;
     fn min_value(&self) -> u64;
     fn max_value(&self) -> u64;
+    fn num_vals(&self) -> u64;
+    /// Returns a iterator over the data
+    fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = u64> + 'a> {
+        Box::new((0..self.num_vals()).map(|idx| self.get_val(idx)))
+    }
 }
 
 #[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Clone, Copy)]
@@ -60,11 +63,25 @@ impl FastFieldCodecType {
 
 /// The FastFieldSerializerEstimate trait is required on all variants
 /// of fast field compressions, to decide which one to choose.
-pub trait FastFieldCodecSerializer {
+pub trait FastFieldCodec {
     /// A codex needs to provide a unique name and id, which is
     /// used for debugging and de/serialization.
     const CODEC_TYPE: FastFieldCodecType;
 
+    type Reader: FastFieldDataAccess;
+
+    /// Reads the metadata and returns the CodecReader
+    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self::Reader>;
+
+    /// Serializes the data using the serializer into write.
+    ///
+    /// The fastfield_accessor iterator should be preferred over using fastfield_accessor for
+    /// performance reasons.
+    fn serialize(
+        write: &mut impl Write,
+        fastfield_accessor: &dyn FastFieldDataAccess,
+    ) -> io::Result<()>;
+
     /// Check if the Codec is able to compress the data
     fn is_applicable(fastfield_accessor: &impl FastFieldDataAccess) -> bool;
 
@@ -74,40 +91,6 @@ pub trait FastFieldCodecSerializer {
     /// It could make sense to also return a value representing
     /// computational complexity.
     fn estimate(fastfield_accessor: &impl FastFieldDataAccess) -> f32;
-
-    /// Serializes the data using the serializer into write.
-    ///
-    /// The fastfield_accessor iterator should be preferred over using fastfield_accessor for
-    /// performance reasons.
-    fn serialize(
-        write: &mut impl Write,
-        fastfield_accessor: &dyn FastFieldDataAccess,
-    ) -> io::Result<()>;
-}
-
-/// FastFieldDataAccess is the trait to access fast field data during serialization and estimation.
-pub trait FastFieldDataAccess {
-    /// Return the value associated to the given position.
-    ///
-    /// Whenever possible use the Iterator passed to the fastfield creation instead, for performance
-    /// reasons.
-    ///
-    /// # Panics
-    ///
-    /// May panic if `position` is greater than the index.
-    fn get_val(&self, position: u64) -> u64;
-
-    /// Returns a iterator over the data
-    fn iter(&self) -> Box<dyn Iterator<Item = u64> + '_>;
-
-    /// min value of the data
-    fn min_value(&self) -> u64;
-
-    /// max value of the data
-    fn max_value(&self) -> u64;
-
-    /// num vals
-    fn num_vals(&self) -> u64;
 }
 
 #[derive(Debug, Clone)]
@@ -165,26 +148,24 @@ mod tests {
     use proptest::arbitrary::any;
     use proptest::proptest;
 
-    use crate::bitpacked::{BitpackedReader, BitpackedSerializer};
-    use crate::blockwise_linear::{BlockwiseLinearReader, BlockwiseLinearSerializer};
-    use crate::linear::{LinearReader, LinearSerializer};
+    use crate::bitpacked::BitpackedCodec;
+    use crate::blockwise_linear::BlockwiseLinearCodec;
+    use crate::linear::LinearCodec;
 
-    pub fn create_and_validate<S: FastFieldCodecSerializer, R: FastFieldCodecReader>(
-        data: &[u64],
-        name: &str,
-    ) -> (f32, f32) {
-        if !S::is_applicable(&data) {
+    pub fn create_and_validate<Codec: FastFieldCodec>(data: &[u64], name: &str) -> (f32, f32) {
+        if !Codec::is_applicable(&data) {
             return (f32::MAX, 0.0);
         }
-        let estimation = S::estimate(&data);
+        let estimation = Codec::estimate(&data);
         let mut out: Vec<u8> = Vec::new();
-        S::serialize(&mut out, &data).unwrap();
+        Codec::serialize(&mut out, &data).unwrap();
 
         let actual_compression = out.len() as f32 / (data.len() as f32 * 8.0);
 
-        let reader = R::open_from_bytes(OwnedBytes::new(out)).unwrap();
+        let reader = Codec::open_from_bytes(OwnedBytes::new(out)).unwrap();
+        assert_eq!(reader.num_vals(), data.len() as u64);
         for (doc, orig_val) in data.iter().enumerate() {
-            let val = reader.get_u64(doc as u64);
+            let val = reader.get_val(doc as u64);
             if val != *orig_val {
                 panic!(
                     "val {val:?} does not match orig_val {orig_val:?}, in data set {name}, data \
@@ -198,16 +179,16 @@ mod tests {
     proptest! {
         #[test]
         fn test_proptest_small(data in proptest::collection::vec(any::<u64>(), 1..10)) {
-            create_and_validate::<LinearSerializer, LinearReader>(&data, "proptest linearinterpol");
-            create_and_validate::<BlockwiseLinearSerializer, BlockwiseLinearReader>(&data, "proptest multilinearinterpol");
-            create_and_validate::<BitpackedSerializer, BitpackedReader>(&data, "proptest bitpacked");
+            create_and_validate::<LinearCodec>(&data, "proptest linearinterpol");
+            create_and_validate::<BlockwiseLinearCodec>(&data, "proptest multilinearinterpol");
+            create_and_validate::<BitpackedCodec>(&data, "proptest bitpacked");
         }
 
         #[test]
         fn test_proptest_large(data in proptest::collection::vec(any::<u64>(), 1..6000)) {
-            create_and_validate::<LinearSerializer, LinearReader>(&data, "proptest linearinterpol");
-            create_and_validate::<BlockwiseLinearSerializer, BlockwiseLinearReader>(&data, "proptest multilinearinterpol");
-            create_and_validate::<BitpackedSerializer, BitpackedReader>(&data, "proptest bitpacked");
+            create_and_validate::<LinearCodec>(&data, "proptest linearinterpol");
+            create_and_validate::<BlockwiseLinearCodec>(&data, "proptest multilinearinterpol");
+            create_and_validate::<BitpackedCodec>(&data, "proptest bitpacked");
         }
 
     }
@@ -228,10 +209,10 @@ mod tests {
         data_and_names
     }
 
-    fn test_codec<S: FastFieldCodecSerializer, R: FastFieldCodecReader>() {
-        let codec_name = format!("{:?}", S::CODEC_TYPE);
+    fn test_codec<C: FastFieldCodec>() {
+        let codec_name = format!("{:?}", C::CODEC_TYPE);
         for (data, dataset_name) in get_codec_test_data_sets() {
-            let (estimate, actual) = crate::tests::create_and_validate::<S, R>(&data, dataset_name);
+            let (estimate, actual) = crate::tests::create_and_validate::<C>(&data, dataset_name);
             let result = if estimate == f32::MAX {
                 "Disabled".to_string()
             } else {
@@ -242,15 +223,15 @@ mod tests {
     }
     #[test]
     fn test_codec_bitpacking() {
-        test_codec::<BitpackedSerializer, BitpackedReader>();
+        test_codec::<BitpackedCodec>();
     }
     #[test]
     fn test_codec_interpolation() {
-        test_codec::<LinearSerializer, LinearReader>();
+        test_codec::<LinearCodec>();
     }
     #[test]
     fn test_codec_multi_interpolation() {
-        test_codec::<BlockwiseLinearSerializer, BlockwiseLinearReader>();
+        test_codec::<BlockwiseLinearCodec>();
     }
 
     use super::*;
@@ -259,24 +240,24 @@ mod tests {
     fn estimation_good_interpolation_case() {
         let data = (10..=20000_u64).collect::<Vec<_>>();
 
-        let linear_interpol_estimation = LinearSerializer::estimate(&data);
+        let linear_interpol_estimation = LinearCodec::estimate(&data);
         assert_le!(linear_interpol_estimation, 0.01);
 
-        let multi_linear_interpol_estimation = BlockwiseLinearSerializer::estimate(&data);
+        let multi_linear_interpol_estimation = BlockwiseLinearCodec::estimate(&data);
         assert_le!(multi_linear_interpol_estimation, 0.2);
         assert_le!(linear_interpol_estimation, multi_linear_interpol_estimation);
 
-        let bitpacked_estimation = BitpackedSerializer::estimate(&data);
+        let bitpacked_estimation = BitpackedCodec::estimate(&data);
         assert_le!(linear_interpol_estimation, bitpacked_estimation);
     }
     #[test]
     fn estimation_test_bad_interpolation_case() {
         let data = vec![200, 10, 10, 10, 10, 1000, 20];
 
-        let linear_interpol_estimation = LinearSerializer::estimate(&data);
+        let linear_interpol_estimation = LinearCodec::estimate(&data);
         assert_le!(linear_interpol_estimation, 0.32);
 
-        let bitpacked_estimation = BitpackedSerializer::estimate(&data);
+        let bitpacked_estimation = BitpackedCodec::estimate(&data);
         assert_le!(bitpacked_estimation, linear_interpol_estimation);
     }
     #[test]
@@ -286,10 +267,10 @@ mod tests {
 
         // in this case the linear interpolation can't in fact not be worse than bitpacking,
         // but the estimator adds some threshold, which leads to estimated worse behavior
-        let linear_interpol_estimation = LinearSerializer::estimate(&data);
+        let linear_interpol_estimation = LinearCodec::estimate(&data);
         assert_le!(linear_interpol_estimation, 0.35);
 
-        let bitpacked_estimation = BitpackedSerializer::estimate(&data);
+        let bitpacked_estimation = BitpackedCodec::estimate(&data);
         assert_le!(bitpacked_estimation, 0.32);
         assert_le!(bitpacked_estimation, linear_interpol_estimation);
     }

fastfield_codecs/src/linear.rs

@@ -5,9 +5,7 @@ use common::{BinarySerializable, FixedSize};
 use ownedbytes::OwnedBytes;
 use tantivy_bitpacker::{compute_num_bits, BitPacker, BitUnpacker};
 
-use crate::{
-    FastFieldCodecReader, FastFieldCodecSerializer, FastFieldCodecType, FastFieldDataAccess,
-};
+use crate::{FastFieldCodec, FastFieldCodecType, FastFieldDataAccess};
 
 /// Depending on the field type, a different
 /// fast field is required.
@@ -59,24 +57,9 @@ impl FixedSize for LinearFooter {
     const SIZE_IN_BYTES: usize = 56;
 }
 
-impl FastFieldCodecReader for LinearReader {
-    /// Opens a fast field given a file.
-    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self> {
-        let footer_offset = bytes.len() - LinearFooter::SIZE_IN_BYTES;
-        let (data, mut footer) = bytes.split(footer_offset);
-        let footer = LinearFooter::deserialize(&mut footer)?;
-        let slope = get_slope(footer.first_val, footer.last_val, footer.num_vals);
-        let num_bits = compute_num_bits(footer.relative_max_value);
-        let bit_unpacker = BitUnpacker::new(num_bits);
-        Ok(LinearReader {
-            data,
-            bit_unpacker,
-            footer,
-            slope,
-        })
-    }
+impl FastFieldDataAccess for LinearReader {
     #[inline]
-    fn get_u64(&self, doc: u64) -> u64 {
+    fn get_val(&self, doc: u64) -> u64 {
         let calculated_value = get_calculated_value(self.footer.first_val, doc, self.slope);
         (calculated_value + self.bit_unpacker.get(doc, &self.data)) - self.footer.offset
     }
@@ -89,11 +72,15 @@ impl FastFieldCodecReader for LinearReader {
     fn max_value(&self) -> u64 {
         self.footer.max_value
     }
+    #[inline]
+    fn num_vals(&self) -> u64 {
+        self.footer.num_vals
+    }
 }
 
 /// Fastfield serializer, which tries to guess values by linear interpolation
 /// and stores the difference bitpacked.
-pub struct LinearSerializer {}
+pub struct LinearCodec;
 
 #[inline]
 pub(crate) fn get_slope(first_val: u64, last_val: u64, num_vals: u64) -> f32 {
@@ -134,9 +121,27 @@ pub fn get_calculated_value(first_val: u64, pos: u64, slope: f32) -> u64 {
     }
 }
 
-impl FastFieldCodecSerializer for LinearSerializer {
+impl FastFieldCodec for LinearCodec {
     const CODEC_TYPE: FastFieldCodecType = FastFieldCodecType::Linear;
 
+    type Reader = LinearReader;
+
+    /// Opens a fast field given a file.
+    fn open_from_bytes(bytes: OwnedBytes) -> io::Result<Self::Reader> {
+        let footer_offset = bytes.len() - LinearFooter::SIZE_IN_BYTES;
+        let (data, mut footer) = bytes.split(footer_offset);
+        let footer = LinearFooter::deserialize(&mut footer)?;
+        let slope = get_slope(footer.first_val, footer.last_val, footer.num_vals);
+        let num_bits = compute_num_bits(footer.relative_max_value);
+        let bit_unpacker = BitUnpacker::new(num_bits);
+        Ok(LinearReader {
+            data,
+            bit_unpacker,
+            footer,
+            slope,
+        })
+    }
+
     /// Creates a new fast field serializer.
     fn serialize(
         write: &mut impl Write,
@@ -260,7 +265,7 @@ mod tests {
     use crate::tests::get_codec_test_data_sets;
 
     fn create_and_validate(data: &[u64], name: &str) -> (f32, f32) {
-        crate::tests::create_and_validate::<LinearSerializer, LinearReader>(data, name)
+        crate::tests::create_and_validate::<LinearCodec, LinearReader>(data, name)
     }
 
     #[test]

fastfield_codecs/src/main.rs

@@ -1,8 +1,8 @@
 #[macro_use]
 extern crate prettytable;
-use fastfield_codecs::blockwise_linear::BlockwiseLinearSerializer;
-use fastfield_codecs::linear::LinearSerializer;
-use fastfield_codecs::{FastFieldCodecSerializer, FastFieldCodecType, FastFieldStats};
+use fastfield_codecs::blockwise_linear::BlockwiseLinearCodec;
+use fastfield_codecs::linear::LinearCodec;
+use fastfield_codecs::{FastFieldCodec, FastFieldCodecType, FastFieldStats};
 use prettytable::{Cell, Row, Table};
 
 fn main() {
@@ -13,11 +13,11 @@ fn main() {
 
     for (data, data_set_name) in get_codec_test_data_sets() {
         let mut results = vec![];
-        let res = serialize_with_codec::<LinearSerializer>(&data);
+        let res = serialize_with_codec::<LinearCodec>(&data);
         results.push(res);
-        let res = serialize_with_codec::<BlockwiseLinearSerializer>(&data);
+        let res = serialize_with_codec::<BlockwiseLinearCodec>(&data);
         results.push(res);
-        let res = serialize_with_codec::<fastfield_codecs::bitpacked::BitpackedSerializer>(&data);
+        let res = serialize_with_codec::<fastfield_codecs::bitpacked::BitpackedCodec>(&data);
         results.push(res);
 
         // let best_estimation_codec = results
@@ -89,19 +89,19 @@ pub fn get_codec_test_data_sets() -> Vec<(Vec<u64>, &'static str)> {
     data_and_names
 }
 
-pub fn serialize_with_codec<S: FastFieldCodecSerializer>(
+pub fn serialize_with_codec<C: FastFieldCodec>(
     data: &[u64],
 ) -> (bool, f32, f32, FastFieldCodecType) {
-    let is_applicable = S::is_applicable(&data);
+    let is_applicable = C::is_applicable(&data);
     if !is_applicable {
-        return (false, 0.0, 0.0, S::CODEC_TYPE);
+        return (false, 0.0, 0.0, C::CODEC_TYPE);
     }
-    let estimation = S::estimate(&data);
+    let estimation = C::estimate(&data);
     let mut out = vec![];
-    S::serialize(&mut out, &data).unwrap();
+    C::serialize(&mut out, &data).unwrap();
 
     let actual_compression = out.len() as f32 / (data.len() * 8) as f32;
-    (true, estimation, actual_compression, S::CODEC_TYPE)
+    (true, estimation, actual_compression, C::CODEC_TYPE)
 }
 
 pub fn stats_from_vec(data: &[u64]) -> FastFieldStats {

src/fastfield/gcd.rs

@@ -3,7 +3,7 @@ use std::num::NonZeroU64;
 
 use common::BinarySerializable;
 use fastdivide::DividerU64;
-use fastfield_codecs::FastFieldCodecReader;
+use fastfield_codecs::{FastFieldCodec, FastFieldDataAccess};
 use ownedbytes::OwnedBytes;
 
 pub const GCD_DEFAULT: u64 = 1;
@@ -12,47 +12,82 @@ pub const GCD_DEFAULT: u64 = 1;
 ///
 /// Holds the data and the codec to the read the data.
 #[derive(Clone)]
-pub struct GCDFastFieldCodec<CodecReader> {
-    gcd: u64,
-    min_value: u64,
+pub struct GCDReader<CodecReader: FastFieldDataAccess> {
+    gcd_params: GCDParams,
     reader: CodecReader,
 }
 
-impl<C: FastFieldCodecReader + Clone> FastFieldCodecReader for GCDFastFieldCodec<C> {
-    /// Opens a fast field given the bytes.
-    fn open_from_bytes(bytes: OwnedBytes) -> std::io::Result<Self> {
-        let footer_offset = bytes.len() - 16;
-        let (body, mut footer) = bytes.split(footer_offset);
-        let gcd = u64::deserialize(&mut footer)?;
-        let min_value = u64::deserialize(&mut footer)?;
-        let reader = C::open_from_bytes(body)?;
-        Ok(GCDFastFieldCodec {
-            gcd,
-            min_value,
-            reader,
-        })
-    }
+#[derive(Debug, Clone, Copy)]
+struct GCDParams {
+    gcd: u64,
+    min_value: u64,
+    num_vals: u64,
+}
 
-    #[inline]
-    fn get_u64(&self, doc: u64) -> u64 {
-        let mut data = self.reader.get_u64(doc);
-        data *= self.gcd;
-        data += self.min_value;
-        data
-    }
-
-    fn min_value(&self) -> u64 {
-        self.min_value + self.reader.min_value() * self.gcd
-    }
-
-    fn max_value(&self) -> u64 {
-        self.min_value + self.reader.max_value() * self.gcd
+impl GCDParams {
+    pub fn eval(&self, val: u64) -> u64 {
+        self.min_value + self.gcd * val
     }
 }
 
-pub fn write_gcd_header<W: Write>(field_write: &mut W, min_value: u64, gcd: u64) -> io::Result<()> {
+impl BinarySerializable for GCDParams {
+    fn serialize<W: Write>(&self, writer: &mut W) -> io::Result<()> {
+        self.gcd.serialize(writer)?;
+        self.min_value.serialize(writer)?;
+        self.num_vals.serialize(writer)?;
+        Ok(())
+    }
+
+    fn deserialize<R: io::Read>(reader: &mut R) -> io::Result<Self> {
+        let gcd: u64 = u64::deserialize(reader)?;
+        let min_value: u64 = u64::deserialize(reader)?;
+        let num_vals: u64 = u64::deserialize(reader)?;
+        Ok(Self {
+            gcd,
+            min_value,
+            num_vals,
+        })
+    }
+}
+
+pub fn open_gcd_from_bytes<WrappedCodec: FastFieldCodec>(
+    bytes: OwnedBytes,
+) -> io::Result<GCDReader<WrappedCodec::Reader>> {
+    let footer_offset = bytes.len() - 24;
+    let (body, mut footer) = bytes.split(footer_offset);
+    let gcd_params = GCDParams::deserialize(&mut footer)?;
+    let reader: WrappedCodec::Reader = WrappedCodec::open_from_bytes(body)?;
+    Ok(GCDReader { gcd_params, reader })
+}
+
+impl<C: FastFieldDataAccess + Clone> FastFieldDataAccess for GCDReader<C> {
+    #[inline]
+    fn get_val(&self, doc: u64) -> u64 {
+        let val = self.reader.get_val(doc);
+        self.gcd_params.eval(val)
+    }
+
+    fn min_value(&self) -> u64 {
+        self.gcd_params.eval(self.reader.min_value())
+    }
+
+    fn max_value(&self) -> u64 {
+        self.gcd_params.eval(self.reader.max_value())
+    }
+    fn num_vals(&self) -> u64 {
+        self.gcd_params.num_vals
+    }
+}
+
+pub fn write_gcd_header<W: Write>(
+    field_write: &mut W,
+    min_value: u64,
+    gcd: u64,
+    num_vals: u64,
+) -> io::Result<()> {
     gcd.serialize(field_write)?;
     min_value.serialize(field_write)?;
+    num_vals.serialize(field_write)?;
     Ok(())
 }
 

src/fastfield/mod.rs

@@ -26,7 +26,7 @@ pub use self::alive_bitset::{intersect_alive_bitsets, write_alive_bitset, AliveB
 pub use self::bytes::{BytesFastFieldReader, BytesFastFieldWriter};
 pub use self::error::{FastFieldNotAvailableError, Result};
 pub use self::facet_reader::FacetReader;
-pub(crate) use self::gcd::{find_gcd, GCDFastFieldCodec, GCD_DEFAULT};
+pub(crate) use self::gcd::{find_gcd, GCDReader, GCD_DEFAULT};
 pub use self::multivalued::{MultiValuedFastFieldReader, MultiValuedFastFieldWriter};
 pub use self::reader::{DynamicFastFieldReader, FastFieldReader};
 pub use self::readers::FastFieldReaders;
@@ -326,7 +326,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 37);
+        assert_eq!(file.len(), 45);
         let composite_file = CompositeFile::open(&file)?;
         let file = composite_file.open_read(*FIELD).unwrap();
         let fast_field_reader = DynamicFastFieldReader::<u64>::open(file)?;
@@ -357,7 +357,7 @@ mod tests {
             serializer.close()?;
         }
         let file = directory.open_read(path)?;
-        assert_eq!(file.len(), 62);
+        assert_eq!(file.len(), 70);
         {
             let fast_fields_composite = CompositeFile::open(&file)?;
             let data = fast_fields_composite.open_read(*FIELD).unwrap();
@@ -393,7 +393,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 35);
+        assert_eq!(file.len(), 43);
         {
             let fast_fields_composite = CompositeFile::open(&file).unwrap();
             let data = fast_fields_composite.open_read(*FIELD).unwrap();
@@ -425,7 +425,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 80043);
+        assert_eq!(file.len(), 80051);
         {
             let fast_fields_composite = CompositeFile::open(&file)?;
             let data = fast_fields_composite.open_read(*FIELD).unwrap();
@@ -896,7 +896,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 36);
+        assert_eq!(file.len(), 44);
         let composite_file = CompositeFile::open(&file)?;
         let file = composite_file.open_read(field).unwrap();
         let fast_field_reader = DynamicFastFieldReader::<bool>::open(file)?;
@@ -932,7 +932,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 48);
+        assert_eq!(file.len(), 56);
         let composite_file = CompositeFile::open(&file)?;
         let file = composite_file.open_read(field).unwrap();
         let fast_field_reader = DynamicFastFieldReader::<bool>::open(file)?;
@@ -966,7 +966,7 @@ mod tests {
             serializer.close().unwrap();
         }
         let file = directory.open_read(path).unwrap();
-        assert_eq!(file.len(), 35);
+        assert_eq!(file.len(), 43);
         let composite_file = CompositeFile::open(&file)?;
         let file = composite_file.open_read(field).unwrap();
         let fast_field_reader = DynamicFastFieldReader::<bool>::open(file)?;

src/fastfield/reader.rs

@@ -3,15 +3,16 @@ use std::marker::PhantomData;
 use std::path::Path;
 
 use common::BinarySerializable;
-use fastfield_codecs::bitpacked::BitpackedReader;
-use fastfield_codecs::blockwise_linear::BlockwiseLinearReader;
-use fastfield_codecs::linear::LinearReader;
-use fastfield_codecs::{FastFieldCodecReader, FastFieldCodecType};
+use fastfield_codecs::bitpacked::{BitpackedCodec, BitpackedReader};
+use fastfield_codecs::blockwise_linear::{BlockwiseLinearCodec, BlockwiseLinearReader};
+use fastfield_codecs::linear::{LinearCodec, LinearReader};
+use fastfield_codecs::{FastFieldCodec, FastFieldCodecType, FastFieldDataAccess};
 
-use super::{FastValue, GCDFastFieldCodec};
+use super::gcd::open_gcd_from_bytes;
+use super::FastValue;
 use crate::directory::{CompositeFile, Directory, FileSlice, OwnedBytes, RamDirectory, WritePtr};
 use crate::error::DataCorruption;
-use crate::fastfield::{CompositeFastFieldSerializer, FastFieldsWriter};
+use crate::fastfield::{CompositeFastFieldSerializer, FastFieldsWriter, GCDReader};
 use crate::schema::{Schema, FAST};
 use crate::DocId;
 
@@ -68,11 +69,11 @@ pub enum DynamicFastFieldReader<Item: FastValue> {
     BlockwiseLinear(FastFieldReaderCodecWrapper<Item, BlockwiseLinearReader>),
 
     /// GCD and Bitpacked compressed fastfield data.
-    BitpackedGCD(FastFieldReaderCodecWrapper<Item, GCDFastFieldCodec<BitpackedReader>>),
+    BitpackedGCD(FastFieldReaderCodecWrapper<Item, GCDReader<BitpackedReader>>),
     /// GCD and Linear interpolated values + bitpacked
-    LinearGCD(FastFieldReaderCodecWrapper<Item, GCDFastFieldCodec<LinearReader>>),
+    LinearGCD(FastFieldReaderCodecWrapper<Item, GCDReader<LinearReader>>),
     /// GCD and Blockwise linear interpolated values + bitpacked
-    BlockwiseLinearGCD(FastFieldReaderCodecWrapper<Item, GCDFastFieldCodec<BlockwiseLinearReader>>),
+    BlockwiseLinearGCD(FastFieldReaderCodecWrapper<Item, GCDReader<BlockwiseLinearReader>>),
 }
 
 impl<Item: FastValue> DynamicFastFieldReader<Item> {
@@ -83,46 +84,27 @@ impl<Item: FastValue> DynamicFastFieldReader<Item> {
     ) -> crate::Result<DynamicFastFieldReader<Item>> {
         let reader = match codec_type {
             FastFieldCodecType::Bitpacked => {
-                DynamicFastFieldReader::Bitpacked(FastFieldReaderCodecWrapper::<
-                    Item,
-                    BitpackedReader,
-                >::open_from_bytes(bytes)?)
+                DynamicFastFieldReader::Bitpacked(BitpackedCodec::open_from_bytes(bytes)?.into())
             }
-            FastFieldCodecType::Linear => DynamicFastFieldReader::Linear(
-                FastFieldReaderCodecWrapper::<Item, LinearReader>::open_from_bytes(bytes)?,
+            FastFieldCodecType::Linear => {
+                DynamicFastFieldReader::Linear(LinearCodec::open_from_bytes(bytes)?.into())
+            }
+            FastFieldCodecType::BlockwiseLinear => DynamicFastFieldReader::BlockwiseLinear(
+                BlockwiseLinearCodec::open_from_bytes(bytes)?.into(),
             ),
-            FastFieldCodecType::BlockwiseLinear => {
-                DynamicFastFieldReader::BlockwiseLinear(FastFieldReaderCodecWrapper::<
-                    Item,
-                    BlockwiseLinearReader,
-                >::open_from_bytes(bytes)?)
-            }
             FastFieldCodecType::Gcd => {
                 let codec_type = FastFieldCodecType::deserialize(&mut bytes)?;
                 match codec_type {
-                    FastFieldCodecType::Bitpacked => {
-                        DynamicFastFieldReader::BitpackedGCD(FastFieldReaderCodecWrapper::<
-                            Item,
-                            GCDFastFieldCodec<BitpackedReader>,
-                        >::open_from_bytes(
-                            bytes
-                        )?)
-                    }
-                    FastFieldCodecType::Linear => {
-                        DynamicFastFieldReader::LinearGCD(FastFieldReaderCodecWrapper::<
-                            Item,
-                            GCDFastFieldCodec<LinearReader>,
-                        >::open_from_bytes(
-                            bytes
-                        )?)
-                    }
+                    FastFieldCodecType::Bitpacked => DynamicFastFieldReader::BitpackedGCD(
+                        open_gcd_from_bytes::<BitpackedCodec>(bytes)?.into(),
+                    ),
+                    FastFieldCodecType::Linear => DynamicFastFieldReader::LinearGCD(
+                        open_gcd_from_bytes::<LinearCodec>(bytes)?.into(),
+                    ),
                     FastFieldCodecType::BlockwiseLinear => {
-                        DynamicFastFieldReader::BlockwiseLinearGCD(FastFieldReaderCodecWrapper::<
-                            Item,
-                            GCDFastFieldCodec<BlockwiseLinearReader>,
-                        >::open_from_bytes(
-                            bytes
-                        )?)
+                        DynamicFastFieldReader::BlockwiseLinearGCD(
+                            open_gcd_from_bytes::<BlockwiseLinearCodec>(bytes)?.into(),
+                        )
                     }
                     FastFieldCodecType::Gcd => {
                         return Err(DataCorruption::comment_only(
@@ -199,34 +181,21 @@ pub struct FastFieldReaderCodecWrapper<Item: FastValue, CodecReader> {
     _phantom: PhantomData<Item>,
 }
 
-impl<Item: FastValue, C: FastFieldCodecReader> FastFieldReaderCodecWrapper<Item, C> {
-    /// Opens a fast field given a file.
-    pub fn open(file: FileSlice) -> crate::Result<Self> {
-        let mut bytes = file.read_bytes()?;
-        let codec_code = bytes.read_u8();
-        let codec_type = FastFieldCodecType::from_code(codec_code).ok_or_else(|| {
-            DataCorruption::comment_only("Unknown codec code does not exist `{codec_code}`")
-        })?;
-        assert_eq!(
-            FastFieldCodecType::Bitpacked,
-            codec_type,
-            "Tried to open fast field as bitpacked encoded (id=1), but got serializer with \
-             different id"
-        );
-        Self::open_from_bytes(bytes)
-    }
-    /// Opens a fast field given the bytes.
-    pub fn open_from_bytes(bytes: OwnedBytes) -> crate::Result<Self> {
-        let reader = C::open_from_bytes(bytes)?;
-        Ok(FastFieldReaderCodecWrapper {
+impl<Item: FastValue, CodecReader> From<CodecReader>
+    for FastFieldReaderCodecWrapper<Item, CodecReader>
+{
+    fn from(reader: CodecReader) -> Self {
+        FastFieldReaderCodecWrapper {
             reader,
             _phantom: PhantomData,
-        })
+        }
     }
+}
 
+impl<Item: FastValue, D: FastFieldDataAccess> FastFieldReaderCodecWrapper<Item, D> {
     #[inline]
     pub(crate) fn get_u64(&self, doc: u64) -> Item {
-        let data = self.reader.get_u64(doc);
+        let data = self.reader.get_val(doc);
         Item::from_u64(data)
     }
 
@@ -249,7 +218,7 @@ impl<Item: FastValue, C: FastFieldCodecReader> FastFieldReaderCodecWrapper<Item,
     }
 }
 
-impl<Item: FastValue, C: FastFieldCodecReader + Clone> FastFieldReader<Item>
+impl<Item: FastValue, C: FastFieldDataAccess + Clone> FastFieldReader<Item>
     for FastFieldReaderCodecWrapper<Item, C>
 {
     /// Return the value associated to the given document.

src/fastfield/serializer/mod.rs

@@ -3,11 +3,11 @@ use std::num::NonZeroU64;
 
 use common::{BinarySerializable, CountingWriter};
 use fastdivide::DividerU64;
-pub use fastfield_codecs::bitpacked::{BitpackedSerializer, BitpackedSerializerLegacy};
-use fastfield_codecs::blockwise_linear::BlockwiseLinearSerializer;
-use fastfield_codecs::linear::LinearSerializer;
+pub use fastfield_codecs::bitpacked::{BitpackedCodec, BitpackedSerializerLegacy};
+use fastfield_codecs::blockwise_linear::BlockwiseLinearCodec;
+use fastfield_codecs::linear::LinearCodec;
 use fastfield_codecs::FastFieldCodecType;
-pub use fastfield_codecs::{FastFieldCodecSerializer, FastFieldDataAccess, FastFieldStats};
+pub use fastfield_codecs::{FastFieldCodec, FastFieldDataAccess, FastFieldStats};
 
 use super::{find_gcd, ALL_CODECS, GCD_DEFAULT};
 use crate::directory::{CompositeWrite, WritePtr};
@@ -64,15 +64,15 @@ impl From<FastFieldCodecType> for FastFieldCodecEnableCheck {
 
 // use this, when this is merged and stabilized explicit_generic_args_with_impl_trait
 // https://github.com/rust-lang/rust/pull/86176
-fn codec_estimation<T: FastFieldCodecSerializer, A: FastFieldDataAccess>(
+fn codec_estimation<C: FastFieldCodec, A: FastFieldDataAccess>(
     fastfield_accessor: &A,
     estimations: &mut Vec<(f32, FastFieldCodecType)>,
 ) {
-    if !T::is_applicable(fastfield_accessor) {
+    if !C::is_applicable(fastfield_accessor) {
         return;
     }
-    let ratio = T::estimate(fastfield_accessor);
-    estimations.push((ratio, T::CODEC_TYPE));
+    let ratio = C::estimate(fastfield_accessor);
+    estimations.push((ratio, C::CODEC_TYPE));
 }
 
 impl CompositeFastFieldSerializer {
@@ -189,7 +189,7 @@ impl CompositeFastFieldSerializer {
             field_write,
             fastfield_accessor,
         )?;
-        write_gcd_header(field_write, base_value, gcd)?;
+        write_gcd_header(field_write, base_value, gcd, num_vals)?;
         Ok(())
     }
 
@@ -204,13 +204,13 @@ impl CompositeFastFieldSerializer {
         let mut estimations = vec![];
 
         if codec_enable_checker.is_enabled(FastFieldCodecType::Bitpacked) {
-            codec_estimation::<BitpackedSerializer, _>(&fastfield_accessor, &mut estimations);
+            codec_estimation::<BitpackedCodec, _>(&fastfield_accessor, &mut estimations);
         }
         if codec_enable_checker.is_enabled(FastFieldCodecType::Linear) {
-            codec_estimation::<LinearSerializer, _>(&fastfield_accessor, &mut estimations);
+            codec_estimation::<LinearCodec, _>(&fastfield_accessor, &mut estimations);
         }
         if codec_enable_checker.is_enabled(FastFieldCodecType::BlockwiseLinear) {
-            codec_estimation::<BlockwiseLinearSerializer, _>(&fastfield_accessor, &mut estimations);
+            codec_estimation::<BlockwiseLinearCodec, _>(&fastfield_accessor, &mut estimations);
         }
         if let Some(broken_estimation) = estimations.iter().find(|estimation| estimation.0.is_nan())
         {
@@ -229,13 +229,13 @@ impl CompositeFastFieldSerializer {
         Self::write_header(field_write, codec_type)?;
         match codec_type {
             FastFieldCodecType::Bitpacked => {
-                BitpackedSerializer::serialize(field_write, &fastfield_accessor)?;
+                BitpackedCodec::serialize(field_write, &fastfield_accessor)?;
             }
             FastFieldCodecType::Linear => {
-                LinearSerializer::serialize(field_write, &fastfield_accessor)?;
+                LinearCodec::serialize(field_write, &fastfield_accessor)?;
             }
             FastFieldCodecType::BlockwiseLinear => {
-                BlockwiseLinearSerializer::serialize(field_write, &fastfield_accessor)?;
+                BlockwiseLinearCodec::serialize(field_write, &fastfield_accessor)?;
             }
             FastFieldCodecType::Gcd => {
                 return Err(io::Error::new(

src/fastfield/writer.rs

@@ -2,12 +2,13 @@ use std::collections::HashMap;
 use std::io;
 
 use common;
+use fastfield_codecs::FastFieldDataAccess;
 use fnv::FnvHashMap;
 use tantivy_bitpacker::BlockedBitpacker;
 
 use super::multivalued::MultiValuedFastFieldWriter;
 use super::serializer::FastFieldStats;
-use super::{FastFieldDataAccess, FastFieldType, FastValue};
+use super::{FastFieldType, FastValue};
 use crate::fastfield::{BytesFastFieldWriter, CompositeFastFieldSerializer};
 use crate::indexer::doc_id_mapping::DocIdMapping;
 use crate::postings::UnorderedTermId;