triedb/pathdb: get rid of min field

triedb/pathdb/history_index.go

@@ -37,7 +37,6 @@ func parseIndex(blob []byte) ([]*indexBlockDesc, error) {
 	}
 	var (
 		lastID   uint32
-		lastMax  uint64
 		descList []*indexBlockDesc
 	)
 	for i := 0; i < len(blob)/indexBlockDescSize; i++ {
@@ -46,19 +45,23 @@ func parseIndex(blob []byte) ([]*indexBlockDesc, error) {
 		if desc.empty() {
 			return nil, errors.New("empty state history index block")
 		}
-		if desc.min > desc.max {
-			return nil, fmt.Errorf("indexBlockDesc: min %d > max %d", desc.min, desc.max)
-		}
 		if lastID != 0 {
 			if lastID+1 != desc.id {
 				return nil, fmt.Errorf("index block id is out of order, last-id: %d, this-id: %d", lastID, desc.id)
 			}
-			if desc.min <= lastMax {
+			// Theoretically, order should be validated between consecutive index blocks,
+			// ensuring that elements within them are strictly ordered. However, since
+			// tracking the minimum element in each block has non-trivial storage overhead,
+			// this check is optimistically omitted.
+			//
+			// TODO(rjl493456442) the minimal element can be resolved from the index block,
+			// evaluate the check cost (mostly IO overhead).
+
+			/*	if desc.min <= lastMax {
 				return nil, fmt.Errorf("index block range is out of order, last-max: %d, this-min: %d", lastMax, desc.min)
-			}
+			}*/
 		}
 		lastID = desc.id
-		lastMax = desc.max
 		descList = append(descList, &desc)
 	}
 	return descList, nil

triedb/pathdb/history_index_block.go

@@ -25,7 +25,7 @@ import (
 )
 
 const (
-	indexBlockDescSize   = 22    // The size of index block descriptor
+	indexBlockDescSize   = 14    // The size of index block descriptor
 	indexBlockEntriesCap = 4096  // The maximum number of entries can be grouped in a block
 	indexBlockRestartLen = 256   // The restart interval length of index block
 	historyIndexBatch    = 65536 // The number of state histories for constructing or deleting indexes together
@@ -35,7 +35,6 @@ const (
 // list of state mutation records associated with a specific state (either an
 // account or a storage slot).
 type indexBlockDesc struct {
-	min     uint64 // The minimum state ID retained within the block
 	max     uint64 // The maximum state ID retained within the block
 	entries uint16 // The number of state mutation records retained within the block
 	id      uint32 // The id of the index block
@@ -59,19 +58,17 @@ func (d *indexBlockDesc) full() bool {
 // encode packs index block descriptor into byte stream.
 func (d *indexBlockDesc) encode() []byte {
 	var buf [indexBlockDescSize]byte
-	binary.BigEndian.PutUint64(buf[:8], d.min)
-	binary.BigEndian.PutUint64(buf[8:16], d.max)
-	binary.BigEndian.PutUint16(buf[16:18], d.entries)
-	binary.BigEndian.PutUint32(buf[18:22], d.id)
+	binary.BigEndian.PutUint64(buf[0:8], d.max)
+	binary.BigEndian.PutUint16(buf[8:10], d.entries)
+	binary.BigEndian.PutUint32(buf[10:14], d.id)
 	return buf[:]
 }
 
 // decode unpacks index block descriptor from byte stream.
 func (d *indexBlockDesc) decode(blob []byte) {
-	d.min = binary.BigEndian.Uint64(blob[:8])
-	d.max = binary.BigEndian.Uint64(blob[8:16])
-	d.entries = binary.BigEndian.Uint16(blob[16:18])
-	d.id = binary.BigEndian.Uint32(blob[18:22])
+	d.max = binary.BigEndian.Uint64(blob[:8])
+	d.entries = binary.BigEndian.Uint16(blob[8:10])
+	d.id = binary.BigEndian.Uint32(blob[10:14])
 }
 
 // parseIndexBlock parses the index block with the supplied byte stream.
@@ -287,9 +284,9 @@ func (b *blockWriter) append(id uint64) error {
 	b.desc.entries++
 
 	// The state history ID must be greater than 0.
-	if b.desc.min == 0 {
-		b.desc.min = id
-	}
+	//if b.desc.min == 0 {
+	//	b.desc.min = id
+	//}
 	b.desc.max = id
 	return nil
 }
@@ -357,7 +354,7 @@ func (b *blockWriter) pop(id uint64) error {
 	}
 	// If there is only one entry left, the entire block should be reset
 	if b.desc.entries == 1 {
-		b.desc.min = 0
+		//b.desc.min = 0
 		b.desc.max = 0
 		b.desc.entries = 0
 		b.restarts = nil

triedb/pathdb/history_index_block_test.go

@@ -155,7 +155,6 @@ func TestBlcokWriterDeleteWithData(t *testing.T) {
 	// Re-construct the block writer with data
 	desc := &indexBlockDesc{
 		id:      0,
-		min:     1,
 		max:     20,
 		entries: 5,
 	}