From 3a90107843a31378bf1ba1f73b3cbca0a7335cb6 Mon Sep 17 00:00:00 2001
From: Gary Rong <garyrong0905@gmail.com>
Date: Tue, 3 Mar 2026 11:59:42 +0800
Subject: [PATCH] core/rawdb: improve freezer TruncateTail

---
 core/rawdb/freezer.go       |  2 ++
 core/rawdb/freezer_table.go | 54 +++++++++++++++++++++++++++++++++++--
 core/rawdb/freezer_utils.go | 52 +++++++++++++++++++++++++++++++++--
 3 files changed, 104 insertions(+), 4 deletions(-)

diff --git a/core/rawdb/freezer.go b/core/rawdb/freezer.go
index 386f5512d2..0e2f86d6ed 100644
--- a/core/rawdb/freezer.go
+++ b/core/rawdb/freezer.go
@@ -320,6 +320,8 @@ func (f *Freezer) TruncateTail(tail uint64) (uint64, error) {
 		}
 	}
 	f.tail.Store(tail)
+
+	// Update the head if the requested tail exceeds the current head
 	if f.head.Load() < tail {
 		f.head.Store(tail)
 	}
diff --git a/core/rawdb/freezer_table.go b/core/rawdb/freezer_table.go
index 7c15978e48..31f3e233b5 100644
--- a/core/rawdb/freezer_table.go
+++ b/core/rawdb/freezer_table.go
@@ -707,12 +707,13 @@ func (t *freezerTable) truncateTail(items uint64) error {
 	t.lock.Lock()
 	defer t.lock.Unlock()
 
-	// Ensure the given truncate target falls in the correct range
+	// Short-circuit if the requested tail deletion points to a stale position
 	if t.itemHidden.Load() >= items {
 		return nil
 	}
+	// If the requested tail exceeds the current head, reset the entire table
 	if t.items.Load() < items {
-		return errors.New("truncation above head")
+		return t.resetTo(items)
 	}
 	// Load the new tail index by the given new tail position
 	var (
@@ -835,6 +836,55 @@ func (t *freezerTable) truncateTail(items uint64) error {
 	return nil
 }
 
+// resetTo clears the entire table and sets both the head and tail to the given
+// value. It assumes the caller holds the lock and that tail > t.items.
+func (t *freezerTable) resetTo(tail uint64) error {
+	// Sync the entire table before resetting, eliminating the potential
+	// data corruption.
+	err := t.Sync()
+	if err != nil {
+		return err
+	}
+	// Update the index file to reflect the new offset
+	if err := t.index.Close(); err != nil {
+		return err
+	}
+	entry := &indexEntry{
+		filenum: t.headId + 1,
+		offset:  uint32(tail),
+	}
+	if err := reset(t.index.Name(), entry.append(nil)); err != nil {
+		return err
+	}
+	if err := t.metadata.setFlushOffset(indexEntrySize, true); err != nil {
+		return err
+	}
+	t.index, err = openFreezerFileForAppend(t.index.Name())
+	if err != nil {
+		return err
+	}
+
+	// Purge all the existing data file
+	if err := t.head.Close(); err != nil {
+		return err
+	}
+	t.headId = t.headId + 1
+	t.tailId = t.headId
+
+	t.head, err = t.openFile(t.headId, openFreezerFileForAppend)
+	if err != nil {
+		return err
+	}
+	t.releaseFilesBefore(t.headId, true)
+
+	t.items.Store(tail)
+	t.itemOffset.Store(tail)
+	t.itemHidden.Store(tail)
+	t.sizeGauge.Update(0)
+
+	return nil
+}
+
 // Close closes all opened files and finalizes the freezer table for use.
 // This operation must be completed before shutdown to prevent the loss of
 // recent writes.
diff --git a/core/rawdb/freezer_utils.go b/core/rawdb/freezer_utils.go
index 752e95ba6a..7786b7a990 100644
--- a/core/rawdb/freezer_utils.go
+++ b/core/rawdb/freezer_utils.go
@@ -22,6 +22,19 @@ import (
 	"path/filepath"
 )
 
+func atomicRename(src, dest string) error {
+	if err := os.Rename(src, dest); err != nil {
+		return err
+	}
+	dir, err := os.Open(filepath.Dir(src))
+	if err != nil {
+		return err
+	}
+	defer dir.Close()
+
+	return dir.Sync()
+}
+
 // copyFrom copies data from 'srcPath' at offset 'offset' into 'destPath'.
 // The 'destPath' is created if it doesn't exist, otherwise it is overwritten.
 // Before the copy is executed, there is a callback can be registered to
@@ -73,13 +86,48 @@ func copyFrom(srcPath, destPath string, offset uint64, before func(f *os.File) e
 		return err
 	}
 	f = nil
-	return os.Rename(fname, destPath)
+
+	return atomicRename(fname, destPath)
+}
+
+// reset atomically replaces the file at the given path with the provided content.
+func reset(path string, content []byte) error {
+	// Create a temp file in the same dir where we want it to wind up
+	f, err := os.CreateTemp(filepath.Dir(path), "*")
+	if err != nil {
+		return err
+	}
+	fname := f.Name()
+
+	// Clean up the leftover file
+	defer func() {
+		if f != nil {
+			f.Close()
+		}
+		os.Remove(fname)
+	}()
+
+	// Write the content into the temp file
+	_, err = f.Write(content)
+	if err != nil {
+		return err
+	}
+	// Permanently persist the content into disk
+	if err := f.Sync(); err != nil {
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+	f = nil
+
+	return atomicRename(fname, path)
 }
 
 // openFreezerFileForAppend opens a freezer table file and seeks to the end
 func openFreezerFileForAppend(filename string) (*os.File, error) {
 	// Open the file without the O_APPEND flag
-	// because it has differing behaviour during Truncate operations
+	// because it has differing behavior during Truncate operations
 	// on different OS's
 	file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0644)
 	if err != nil {