Experiment (#3333)

parquet/src/bloom_filter/mod.rs

@@ -49,38 +49,82 @@ const SALT: [u32; 8] = [
 
 /// Each block is 256 bits, broken up into eight contiguous "words", each consisting of 32 bits.
 /// Each word is thought of as an array of bits; each bit is either "set" or "not set".
-type Block = [u32; 8];
-
-/// takes as its argument a single unsigned 32-bit integer and returns a block in which each
-/// word has exactly one bit set.
-fn mask(x: u32) -> Block {
-    let mut result = [0_u32; 8];
-    for i in 0..8 {
-        // wrapping instead of checking for overflow
-        let y = x.wrapping_mul(SALT[i]);
-        let y = y >> 27;
-        result[i] = 1 << y;
+#[derive(Debug, Copy, Clone)]
+struct Block([u32; 8]);
+impl Block {
+    const ZERO: Block = Block([0; 8]);
+
+    /// takes as its argument a single unsigned 32-bit integer and returns a block in which each
+    /// word has exactly one bit set.
+    fn mask(x: u32) -> Self {
+        let mut result = [0_u32; 8];
+        for i in 0..8 {
+            // wrapping instead of checking for overflow
+            let y = x.wrapping_mul(SALT[i]);
+            let y = y >> 27;
+            result[i] = 1 << y;
+        }
+        Self(result)
+    }
+
+    #[inline]
+    #[cfg(target_endian = "little")]
+    fn to_le_bytes(self) -> [u8; 32] {
+        self.to_ne_bytes()
+    }
+
+    #[inline]
+    #[cfg(not(target_endian = "little"))]
+    fn to_le_bytes(self) -> [u8; 32] {
+        self.swap_bytes().to_ne_bytes()
+    }
+
+    #[inline]
+    fn to_ne_bytes(self) -> [u8; 32] {
+        unsafe { std::mem::transmute(self) }
+    }
+
+    #[inline]
+    #[cfg(not(target_endian = "little"))]
+    fn swap_bytes(mut self) -> Self {
+        self.0.iter_mut().for_each(|x| *x = x.swap_bytes());
+        self
+    }
+
+    /// setting every bit in the block that was also set in the result from mask
+    fn insert(&mut self, hash: u32) {
+        let mask = Self::mask(hash);
+        for i in 0..8 {
+            self[i] |= mask[i];
+        }
+    }
+
+    /// returns true when every bit that is set in the result of mask is also set in the block.
+    fn check(&self, hash: u32) -> bool {
+        let mask = Self::mask(hash);
+        for i in 0..8 {
+            if self[i] & mask[i] == 0 {
+                return false;
+            }
+        }
+        true
     }
-    result
 }
 
-/// setting every bit in the block that was also set in the result from mask
-fn block_insert(block: &mut Block, hash: u32) {
-    let mask = mask(hash);
-    for i in 0..8 {
-        block[i] |= mask[i];
+impl std::ops::Index<usize> for Block {
+    type Output = u32;
+
+    #[inline]
+    fn index(&self, index: usize) -> &Self::Output {
+        self.0.index(index)
     }
 }
 
-/// returns true when every bit that is set in the result of mask is also set in the block.
-fn block_check(block: &Block, hash: u32) -> bool {
-    let mask = mask(hash);
-    for i in 0..8 {
-        if block[i] & mask[i] == 0 {
-            return false;
-        }
+impl std::ops::IndexMut<usize> for Block {
+    #[inline]
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        self.0.index_mut(index)
     }
-    true
 }
 
 /// A split block Bloom filter. The creation of this structure is based on the
@@ -166,7 +210,7 @@ impl Sbbf {
         let data = bitset
             .chunks_exact(4 * 8)
             .map(|chunk| {
-                let mut block = [0_u32; 8];
+                let mut block = Block::ZERO;
                 for (i, word) in chunk.chunks_exact(4).enumerate() {
                     block[i] = u32::from_le_bytes(word.try_into().unwrap());
                 }
@@ -194,14 +238,14 @@ impl Sbbf {
     /// Write the bitset in serialized form to the writer.
     fn write_bitset<W: Write>(&self, mut writer: W) -> Result<(), ParquetError> {
         for block in &self.0 {
-            for word in block {
-                writer.write_all(&word.to_le_bytes()).map_err(|e| {
+            writer
+                .write_all(block.to_le_bytes().as_slice())
+                .map_err(|e| {
                     ParquetError::General(format!(
                         "Could not write bloom filter bit set: {}",
                         e
                     ))
                 })?;
-            }
         }
         Ok(())
     }
@@ -271,8 +315,7 @@ impl Sbbf {
     /// Insert a hash into the filter
     fn insert_hash(&mut self, hash: u64) {
         let block_index = self.hash_to_block_index(hash);
-        let block = &mut self.0[block_index];
-        block_insert(block, hash as u32);
+        self.0[block_index].insert(hash as u32)
     }
 
     /// Check if an [AsBytes] value is probably present or definitely absent in the filter
@@ -285,8 +328,7 @@ impl Sbbf {
     /// but will always return false if a hash has not been inserted.
     fn check_hash(&self, hash: u64) -> bool {
         let block_index = self.hash_to_block_index(hash);
-        let block = &self.0[block_index];
-        block_check(block, hash as u32)
+        self.0[block_index].check(hash as u32)
     }
 }
 
@@ -316,23 +358,23 @@ mod tests {
     #[test]
     fn test_mask_set_quick_check() {
         for i in 0..1_000_000 {
-            let result = mask(i);
-            assert!(result.iter().all(|&x| x.count_ones() == 1));
+            let result = Block::mask(i);
+            assert!(result.0.iter().all(|&x| x.count_ones() == 1));
         }
     }
 
     #[test]
     fn test_block_insert_and_check() {
         for i in 0..1_000_000 {
-            let mut block = [0_u32; 8];
-            block_insert(&mut block, i);
-            assert!(block_check(&block, i));
+            let mut block = Block::ZERO;
+            block.insert(i);
+            assert!(block.check(i));
         }
     }
 
     #[test]
     fn test_sbbf_insert_and_check() {
-        let mut sbbf = Sbbf(vec![[0_u32; 8]; 1_000]);
+        let mut sbbf = Sbbf(vec![Block::ZERO; 1_000]);
         for i in 0..1_000_000 {
             sbbf.insert(&i);
             assert!(sbbf.check(&i));