perf: avoid reopening .csoff on every changeset lookup

crates/static-file/types/src/changeset_offsets.rs

@@ -6,7 +6,8 @@
 use crate::ChangesetOffset;
 use std::{
     fs::{File, OpenOptions},
-    io::{self, Read, Seek, SeekFrom, Write},
+    io::{self, Write},
+    os::unix::fs::FileExt,
     path::Path,
 };
 
@@ -177,16 +178,14 @@ impl ChangesetOffsetReader {
 
     /// Reads a single changeset offset by block index.
     /// Returns None if index is out of bounds.
-    pub fn get(&mut self, block_index: u64) -> io::Result<Option<ChangesetOffset>> {
+    pub fn get(&self, block_index: u64) -> io::Result<Option<ChangesetOffset>> {
         if block_index >= self.len {
             return Ok(None);
         }
 
         let byte_pos = block_index * Self::RECORD_SIZE as u64;
-        self.file.seek(SeekFrom::Start(byte_pos))?;
-
         let mut buf = [0u8; Self::RECORD_SIZE];
-        self.file.read_exact(&mut buf)?;
+        self.file.read_exact_at(&mut buf, byte_pos)?;
 
         let offset = u64::from_le_bytes(buf[..8].try_into().unwrap());
         let num_changes = u64::from_le_bytes(buf[8..].try_into().unwrap());
@@ -195,21 +194,21 @@ impl ChangesetOffsetReader {
     }
 
     /// Reads a range of changeset offsets.
-    pub fn get_range(&mut self, start: u64, end: u64) -> io::Result<Vec<ChangesetOffset>> {
+    pub fn get_range(&self, start: u64, end: u64) -> io::Result<Vec<ChangesetOffset>> {
         let end = end.min(self.len);
         if start >= end {
             return Ok(Vec::new());
         }
 
         let count = (end - start) as usize;
         let byte_pos = start * Self::RECORD_SIZE as u64;
-        self.file.seek(SeekFrom::Start(byte_pos))?;
 
         let mut result = Vec::with_capacity(count);
         let mut buf = [0u8; Self::RECORD_SIZE];
 
-        for _ in 0..count {
-            self.file.read_exact(&mut buf)?;
+        for i in 0..count {
+            let pos = byte_pos + (i as u64) * Self::RECORD_SIZE as u64;
+            self.file.read_exact_at(&mut buf, pos)?;
             let offset = u64::from_le_bytes(buf[..8].try_into().unwrap());
             let num_changes = u64::from_le_bytes(buf[8..].try_into().unwrap());
             result.push(ChangesetOffset::new(offset, num_changes));
@@ -251,7 +250,7 @@ mod tests {
 
         // Read
         {
-            let mut reader = ChangesetOffsetReader::new(&path, 3).unwrap();
+            let reader = ChangesetOffsetReader::new(&path, 3).unwrap();
             assert_eq!(reader.len(), 3);
 
             let entry = reader.get(0).unwrap().unwrap();
@@ -284,7 +283,7 @@ mod tests {
         writer.truncate(2).unwrap();
         assert_eq!(writer.len(), 2);
 
-        let mut reader = ChangesetOffsetReader::new(&path, 2).unwrap();
+        let reader = ChangesetOffsetReader::new(&path, 2).unwrap();
         assert_eq!(reader.len(), 2);
         assert!(reader.get(2).unwrap().is_none());
     }
@@ -317,7 +316,7 @@ mod tests {
         assert_eq!(std::fs::metadata(&path).unwrap().len(), 16);
 
         // Verify the complete record is readable
-        let mut reader = ChangesetOffsetReader::new(&path, 1).unwrap();
+        let reader = ChangesetOffsetReader::new(&path, 1).unwrap();
         assert_eq!(reader.len(), 1);
         let entry = reader.get(0).unwrap().unwrap();
         assert_eq!(entry.offset(), 100);
@@ -340,7 +339,7 @@ mod tests {
         }
 
         // Open with len=2, ignoring the 3rd record
-        let mut reader = ChangesetOffsetReader::new(&path, 2).unwrap();
+        let reader = ChangesetOffsetReader::new(&path, 2).unwrap();
         assert_eq!(reader.len(), 2);
 
         // First two records should be readable
@@ -397,7 +396,7 @@ mod tests {
 
         // Verify the records are correct
         {
-            let mut reader = ChangesetOffsetReader::new(&path, 3).unwrap();
+            let reader = ChangesetOffsetReader::new(&path, 3).unwrap();
             assert_eq!(reader.len(), 3);
 
             let entry0 = reader.get(0).unwrap().unwrap();

crates/static-file/types/src/lib.rs

@@ -15,9 +15,9 @@ mod compression;
 mod event;
 mod segment;
 
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", unix))]
 mod changeset_offsets;
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", unix))]
 pub use changeset_offsets::{ChangesetOffsetReader, ChangesetOffsetWriter};
 
 use alloy_primitives::BlockNumber;

crates/storage/provider/src/providers/static_file/jar.rs

@@ -17,7 +17,7 @@ use reth_db::static_file::{
 use reth_db_api::table::{Decompress, Value};
 use reth_node_types::NodePrimitives;
 use reth_primitives_traits::{SealedHeader, SignedTransaction};
-use reth_static_file_types::{ChangesetOffset, ChangesetOffsetReader};
+use reth_static_file_types::ChangesetOffset;
 use reth_storage_api::range_size_hint;
 use reth_storage_errors::provider::{ProviderError, ProviderResult};
 use std::{
@@ -111,15 +111,11 @@ impl<'a, N: NodePrimitives> StaticFileJarProvider<'a, N> {
             return Ok(None);
         };
 
-        let csoff_path = self.data_path().with_extension("csoff");
-        if !csoff_path.exists() {
-            return Ok(None);
+        if let Some(reader) = self.jar.value().csoff_reader() {
+            reader.get(index).map_err(ProviderError::other)
+        } else {
+            Ok(None)
         }
-
-        let len = header.changeset_offsets_len();
-        let mut reader =
-            ChangesetOffsetReader::new(&csoff_path, len).map_err(ProviderError::other)?;
-        reader.get(index).map_err(ProviderError::other)
     }
 
     /// Reads all changeset offsets from the sidecar file.
@@ -138,15 +134,12 @@ impl<'a, N: NodePrimitives> StaticFileJarProvider<'a, N> {
             return Ok(Some(Vec::new()));
         }
 
-        let csoff_path = self.data_path().with_extension("csoff");
-        if !csoff_path.exists() {
-            return Ok(None);
+        if let Some(reader) = self.jar.value().csoff_reader() {
+            let offsets = reader.get_range(0, len).map_err(ProviderError::other)?;
+            Ok(Some(offsets))
+        } else {
+            Ok(None)
         }
-
-        let mut reader =
-            ChangesetOffsetReader::new(&csoff_path, len).map_err(ProviderError::other)?;
-        let offsets = reader.get_range(0, len).map_err(ProviderError::other)?;
-        Ok(Some(offsets))
     }
 }
 

crates/storage/provider/src/providers/static_file/mod.rs

@@ -16,9 +16,9 @@ mod metrics;
 mod writer_tests;
 
 use reth_nippy_jar::NippyJar;
-use reth_static_file_types::{SegmentHeader, StaticFileSegment};
+use reth_static_file_types::{ChangesetOffsetReader, SegmentHeader, StaticFileSegment};
 use reth_storage_errors::provider::{ProviderError, ProviderResult};
-use std::{ops::Deref, sync::Arc};
+use std::{io, ops::Deref, sync::Arc};
 
 /// Alias type for each specific `NippyJar`.
 type LoadedJarRef<'a> =
@@ -29,14 +29,28 @@ type LoadedJarRef<'a> =
 pub struct LoadedJar {
     jar: NippyJar<SegmentHeader>,
     mmap_handle: Arc<reth_nippy_jar::DataReader>,
+    csoff_reader: Option<ChangesetOffsetReader>,
 }
 
 impl LoadedJar {
     fn new(jar: NippyJar<SegmentHeader>) -> ProviderResult<Self> {
         match jar.open_data_reader() {
             Ok(data_reader) => {
                 let mmap_handle = Arc::new(data_reader);
-                Ok(Self { jar, mmap_handle })
+
+                let csoff_reader = if jar.user_header().segment().is_change_based() {
+                    let csoff_path = jar.data_path().with_extension("csoff");
+                    let len = jar.user_header().changeset_offsets_len();
+                    match ChangesetOffsetReader::new(&csoff_path, len) {
+                        Ok(reader) => Some(reader),
+                        Err(err) if err.kind() == io::ErrorKind::NotFound && len == 0 => None,
+                        Err(err) => return Err(ProviderError::other(err)),
+                    }
+                } else {
+                    None
+                };
+
+                Ok(Self { jar, mmap_handle, csoff_reader })
             }
             Err(e) => Err(ProviderError::other(e)),
         }
@@ -55,6 +69,11 @@ impl LoadedJar {
     fn size(&self) -> usize {
         self.mmap_handle.size() + self.mmap_handle.offsets_size()
     }
+
+    /// Returns a reference to the cached changeset offset reader.
+    const fn csoff_reader(&self) -> Option<&ChangesetOffsetReader> {
+        self.csoff_reader.as_ref()
+    }
 }
 
 impl Deref for LoadedJar {

crates/storage/provider/src/providers/static_file/writer.rs

@@ -400,7 +400,7 @@ impl<N: NodePrimitives> StaticFileProviderRW<N> {
 
         // Step 2: Validate sidecar offsets against actual NippyJar state
         let valid_blocks = if actual_sidecar_blocks > 0 {
-            let mut reader = ChangesetOffsetReader::new(&csoff_path, actual_sidecar_blocks)
+            let reader = ChangesetOffsetReader::new(&csoff_path, actual_sidecar_blocks)
                 .map_err(ProviderError::other)?;
 
             // Find last block where offset + num_changes <= actual_nippy_rows
@@ -896,7 +896,7 @@ impl<N: NodePrimitives> StaticFileProviderRW<N> {
             // Read offset for the block after last_block from sidecar.
             // Use committed length from header, ignoring any uncommitted records
             // that may exist in the file after a crash.
-            let mut reader = ChangesetOffsetReader::new(&csoff_path, changeset_offsets_len)
+            let reader = ChangesetOffsetReader::new(&csoff_path, changeset_offsets_len)
                 .map_err(ProviderError::other)?;
             if let Some(next_offset) = reader.get(blocks_to_keep).map_err(ProviderError::other)? {
                 next_offset.offset()

crates/storage/provider/src/providers/static_file/writer_tests.rs

@@ -614,7 +614,7 @@ mod tests {
         assert_eq!(get_header_block_count(&provider, 0), 5);
 
         // Verify offsets are correct
-        let mut reader = ChangesetOffsetReader::new(&sidecar_path, 5).unwrap();
+        let reader = ChangesetOffsetReader::new(&sidecar_path, 5).unwrap();
 
         let o0 = reader.get(0).unwrap().unwrap();
         assert_eq!(o0.offset(), 0);