[thrift-remodel] Refactor Thrift encryption and store encodings as bitmask

parquet/src/basic.rs

@@ -25,6 +25,7 @@ use std::str::FromStr;
 use std::{fmt, str};
 
 pub use crate::compression::{BrotliLevel, GzipLevel, ZstdLevel};
+use crate::file::metadata::HeapSize;
 use crate::parquet_thrift::{
     ElementType, FieldType, ReadThrift, ThriftCompactInputProtocol, ThriftCompactOutputProtocol,
     WriteThrift, WriteThriftField,
@@ -724,6 +725,123 @@ impl FromStr for Encoding {
     }
 }
 
+/// A bitmask representing the [`Encoding`]s employed while encoding a Parquet column chunk.
+///
+/// The Parquet [`ColumnMetaData`] struct contains an array that indicates what encodings were
+/// used when writing that column chunk. For memory and performance reasons, this crate reduces
+/// that array to bitmask, where each bit position represents a different [`Encoding`]. This
+/// struct contains that bitmask, and provides methods to interact with the data.
+///
+/// # Example
+/// ```no_run
+/// # use parquet::file::metadata::ParquetMetaDataReader;
+/// # use parquet::basic::Encoding;
+/// # fn open_parquet_file(path: &str) -> std::fs::File { unimplemented!(); }
+/// // read parquet metadata from a file
+/// let file = open_parquet_file("some_path.parquet");
+/// let mut reader = ParquetMetaDataReader::new();
+/// reader.try_parse(&file).unwrap();
+/// let metadata = reader.finish().unwrap();
+///
+/// // find the encodings used by the first column chunk in the first row group
+/// let col_meta = metadata.row_group(0).column(0);
+/// let encodings = col_meta.encodings_mask();
+///
+/// // check to see if a particular encoding was used
+/// let used_rle = encodings.is_set(Encoding::RLE);
+///
+/// // check to see if all of a set of encodings were used
+/// let used_all = encodings.all_set([Encoding::RLE, Encoding::PLAIN].iter());
+///
+/// // convert mask to a Vec<Encoding>
+/// let encodings_vec = encodings.encodings().collect::<Vec<_>>();
+/// ```
+///
+/// [`ColumnMetaData`]: https://github.com/apache/parquet-format/blob/9fd57b59e0ce1a82a69237dcf8977d3e72a2965d/src/main/thrift/parquet.thrift#L875
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct EncodingMask(i32);
+
+impl EncodingMask {
+    const MAX_ENCODING: i32 = Encoding::BYTE_STREAM_SPLIT as i32;
+
+    /// Create a new `EncodingMask` from an integer.
+    pub fn new(val: i32) -> Self {
+        Self(val)
+    }
+
+    /// Return an integer representation of this `EncodingMask`.
+    pub fn as_i32(&self) -> i32 {
+        self.0
+    }
+
+    /// Create a new `EncodingMask` from a collection of [`Encoding`]s.
+    pub fn new_from_encodings<'a>(encodings: impl Iterator<Item = &'a Encoding>) -> Self {
+        let mut mask = 0;
+        for &e in encodings {
+            mask |= 1 << (e as i32);
+        }
+        Self(mask)
+    }
+
+    /// Test if a given [`Encoding`] is present in this mask.
+    pub fn is_set(&self, val: Encoding) -> bool {
+        self.0 & (1 << (val as i32)) != 0
+    }
+
+    /// Test if all [`Encoding`]s in a given set are present in this mask.
+    pub fn all_set<'a>(&self, mut encodings: impl Iterator<Item = &'a Encoding>) -> bool {
+        encodings.all(|&e| self.is_set(e))
+    }
+
+    /// Return an iterator over all [`Encoding`]s present in this mask.
+    pub fn encodings(&self) -> impl Iterator<Item = Encoding> {
+        Self::mask_to_encodings_iter(self.0)
+    }
+
+    fn mask_to_encodings_iter(mask: i32) -> impl Iterator<Item = Encoding> {
+        (0..=Self::MAX_ENCODING)
+            .filter(move |i| mask & (1 << i) != 0)
+            .map(i32_to_encoding)
+    }
+}
+
+impl HeapSize for EncodingMask {
+    fn heap_size(&self) -> usize {
+        0 // no heap allocations
+    }
+}
+
+impl<'a, R: ThriftCompactInputProtocol<'a>> ReadThrift<'a, R> for EncodingMask {
+    fn read_thrift(prot: &mut R) -> Result<Self> {
+        let mut mask = 0;
+
+        let list_ident = prot.read_list_begin()?;
+        for _ in 0..list_ident.size {
+            let val = i32::read_thrift(prot)?;
+            if (0..=Self::MAX_ENCODING).contains(&val) {
+                mask |= 1 << val;
+            }
+        }
+        Ok(Self(mask))
+    }
+}
+
+#[allow(deprecated)]
+fn i32_to_encoding(val: i32) -> Encoding {
+    match val {
+        0 => Encoding::PLAIN,
+        2 => Encoding::PLAIN_DICTIONARY,
+        3 => Encoding::RLE,
+        4 => Encoding::BIT_PACKED,
+        5 => Encoding::DELTA_BINARY_PACKED,
+        6 => Encoding::DELTA_LENGTH_BYTE_ARRAY,
+        7 => Encoding::DELTA_BYTE_ARRAY,
+        8 => Encoding::RLE_DICTIONARY,
+        9 => Encoding::BYTE_STREAM_SPLIT,
+        _ => panic!("Impossible encoding {val}"),
+    }
+}
+
 // ----------------------------------------------------------------------
 // Mirrors thrift enum `CompressionCodec`
 
@@ -2409,4 +2527,38 @@ mod tests {
         assert_eq!(EdgeInterpolationAlgorithm::ANDOYER.to_string(), "ANDOYER");
         assert_eq!(EdgeInterpolationAlgorithm::KARNEY.to_string(), "KARNEY");
     }
+
+    fn encodings_roundtrip(mut encodings: Vec<Encoding>) {
+        encodings.sort();
+        let mask = EncodingMask::new_from_encodings(encodings.iter());
+        assert!(mask.all_set(encodings.iter()));
+        let v = mask.encodings().collect::<Vec<_>>();
+        assert_eq!(v, encodings);
+    }
+
+    #[test]
+    fn test_encoding_roundtrip() {
+        encodings_roundtrip(
+            [
+                Encoding::RLE,
+                Encoding::PLAIN,
+                Encoding::DELTA_BINARY_PACKED,
+            ]
+            .into(),
+        );
+        encodings_roundtrip([Encoding::RLE_DICTIONARY, Encoding::PLAIN_DICTIONARY].into());
+        encodings_roundtrip([].into());
+        let encodings = [
+            Encoding::PLAIN,
+            Encoding::BIT_PACKED,
+            Encoding::RLE,
+            Encoding::DELTA_BINARY_PACKED,
+            Encoding::DELTA_BYTE_ARRAY,
+            Encoding::DELTA_LENGTH_BYTE_ARRAY,
+            Encoding::PLAIN_DICTIONARY,
+            Encoding::RLE_DICTIONARY,
+            Encoding::BYTE_STREAM_SPLIT,
+        ];
+        encodings_roundtrip(encodings.into());
+    }
 }

parquet/src/column/writer/mod.rs

@@ -27,7 +27,7 @@ use std::collections::{BTreeSet, VecDeque};
 use std::str;
 
 use crate::basic::{
-    BoundaryOrder, Compression, ConvertedType, Encoding, LogicalType, PageType, Type,
+    BoundaryOrder, Compression, ConvertedType, Encoding, EncodingMask, LogicalType, PageType, Type,
 };
 use crate::column::page::{CompressedPage, Page, PageWriteSpec, PageWriter};
 use crate::column::writer::encoder::{ColumnValueEncoder, ColumnValueEncoderImpl, ColumnValues};
@@ -1190,7 +1190,7 @@ impl<'a, E: ColumnValueEncoder> GenericColumnWriter<'a, E> {
 
         let mut builder = ColumnChunkMetaData::builder(self.descr.clone())
             .set_compression(self.codec)
-            .set_encodings(self.encodings.iter().cloned().collect())
+            .set_encodings_mask(EncodingMask::new_from_encodings(self.encodings.iter()))
             .set_page_encoding_stats(self.encoding_stats.clone())
             .set_total_compressed_size(total_compressed_size)
             .set_total_uncompressed_size(total_uncompressed_size)
@@ -1734,7 +1734,10 @@ mod tests {
         assert_eq!(r.rows_written, 4);
 
         let metadata = r.metadata;
-        assert_eq!(metadata.encodings(), &vec![Encoding::PLAIN, Encoding::RLE]);
+        assert_eq!(
+            metadata.encodings().collect::<Vec<_>>(),
+            vec![Encoding::PLAIN, Encoding::RLE]
+        );
         assert_eq!(metadata.num_values(), 4); // just values
         assert_eq!(metadata.dictionary_page_offset(), None);
     }
@@ -2095,8 +2098,8 @@ mod tests {
 
         let metadata = r.metadata;
         assert_eq!(
-            metadata.encodings(),
-            &vec![Encoding::PLAIN, Encoding::RLE, Encoding::RLE_DICTIONARY]
+            metadata.encodings().collect::<Vec<_>>(),
+            vec![Encoding::PLAIN, Encoding::RLE, Encoding::RLE_DICTIONARY]
         );
         assert_eq!(metadata.num_values(), 4);
         assert_eq!(metadata.compressed_size(), 20);
@@ -2221,8 +2224,8 @@ mod tests {
 
         let metadata = r.metadata;
         assert_eq!(
-            metadata.encodings(),
-            &vec![Encoding::PLAIN, Encoding::RLE, Encoding::RLE_DICTIONARY]
+            metadata.encodings().collect::<Vec<_>>(),
+            vec![Encoding::PLAIN, Encoding::RLE, Encoding::RLE_DICTIONARY]
         );
         assert_eq!(metadata.num_values(), 4);
         assert_eq!(metadata.compressed_size(), 20);
@@ -4100,7 +4103,7 @@ mod tests {
             .build();
         let meta = column_write_and_get_metadata::<T>(props, data);
         assert_eq!(meta.dictionary_page_offset(), dictionary_page_offset);
-        assert_eq!(meta.encodings(), encodings);
+        assert_eq!(meta.encodings().collect::<Vec<_>>(), encodings);
         assert_eq!(meta.page_encoding_stats().unwrap(), page_encoding_stats);
     }