From f5db7c9bef448a63d9971822c4a848001b985fb7 Mon Sep 17 00:00:00 2001
From: Alex Sharov <AskAlexSharov@gmail.com>
Date: Tue, 20 Dec 2022 09:28:09 +0700
Subject: [PATCH] e3: kv/temporal prototype 2 (#792)

---
 common/length/length.go                  |  2 +
 kv/kv_interface.go                       |  1 +
 kv/temporal/historyv2/find_by_history.go | 78 ++++++++++++++++++++++++
 state/inverted_index.go                  |  7 +++
 4 files changed, 88 insertions(+)
 create mode 100644 kv/temporal/historyv2/find_by_history.go

diff --git a/common/length/length.go b/common/length/length.go
index 25fabcfee..07836a690 100644
--- a/common/length/length.go
+++ b/common/length/length.go
@@ -24,6 +24,8 @@ const (
 	Addr = 20
 	// BlockNumberLen length of uint64 big endian
 	BlockNum = 8
+	// Ts TimeStamp (BlockNum, TxNum or any other uint64 equivalent of Time)
+	Ts = 8
 	// Incarnation length of uint64 for contract incarnations
 	Incarnation = 8
 )
diff --git a/kv/kv_interface.go b/kv/kv_interface.go
index 47adb3b0c..8a6b631eb 100644
--- a/kv/kv_interface.go
+++ b/kv/kv_interface.go
@@ -26,6 +26,7 @@ import (
 //Naming:
 //  ts - TimeStamp
 //  tx - Database Transaction
+//  txn - Ethereum Transaction (and TxNum - is also number of Etherum Transaction)
 //  RoTx - Read-Only Database Transaction
 //  RwTx - Read-Write Database Transaction
 //  k - key
diff --git a/kv/temporal/historyv2/find_by_history.go b/kv/temporal/historyv2/find_by_history.go
new file mode 100644
index 000000000..42c895f2f
--- /dev/null
+++ b/kv/temporal/historyv2/find_by_history.go
@@ -0,0 +1,78 @@
+/*
+   Copyright 2022 Erigon contributors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package historyv2
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	"github.com/RoaringBitmap/roaring/roaring64"
+	"github.com/ledgerwatch/erigon-lib/common/length"
+	"github.com/ledgerwatch/erigon-lib/kv"
+	"github.com/ledgerwatch/erigon-lib/kv/bitmapdb"
+)
+
+func FindByHistory(indexC kv.Cursor, changesC kv.CursorDupSort, storage bool, key []byte, timestamp uint64) ([]byte, bool, error) {
+	var csBucket string
+	if storage {
+		csBucket = kv.StorageChangeSet
+	} else {
+		csBucket = kv.AccountChangeSet
+	}
+
+	k, v, seekErr := indexC.Seek(Mapper[csBucket].IndexChunkKey(key, timestamp))
+	if seekErr != nil {
+		return nil, false, seekErr
+	}
+
+	if k == nil {
+		return nil, false, nil
+	}
+	if storage {
+		if !bytes.Equal(k[:length.Addr], key[:length.Addr]) ||
+			!bytes.Equal(k[length.Addr:length.Addr+length.Hash], key[length.Addr+length.Incarnation:]) {
+			return nil, false, nil
+		}
+	} else {
+		if !bytes.HasPrefix(k, key) {
+			return nil, false, nil
+		}
+	}
+	index := roaring64.New()
+	if _, err := index.ReadFrom(bytes.NewReader(v)); err != nil {
+		return nil, false, err
+	}
+	found, ok := bitmapdb.SeekInBitmap64(index, timestamp)
+	changeSetBlock := found
+
+	var data []byte
+	var err error
+	if ok {
+		data, err = Mapper[csBucket].Find(changesC, changeSetBlock, key)
+		if err != nil {
+			if !errors.Is(err, ErrNotFound) {
+				return nil, false, fmt.Errorf("finding %x in the changeset %d: %w", key, changeSetBlock, err)
+			}
+			return nil, false, nil
+		}
+	} else {
+		return nil, false, nil
+	}
+
+	return data, true, nil
+}
diff --git a/state/inverted_index.go b/state/inverted_index.go
index 390c69775..1ef06e455 100644
--- a/state/inverted_index.go
+++ b/state/inverted_index.go
@@ -569,6 +569,13 @@ func (it *InvertedIterator) Next() uint64 {
 	it.advance()
 	return n
 }
+func (it *InvertedIterator) ToBitamp() *roaring64.Bitmap {
+	bm := bitmapdb.NewBitmap64()
+	for it.HasNext() {
+		bm.Add(it.Next())
+	}
+	return bm
+}
 
 type InvertedIndexContext struct {
 	ii    *InvertedIndex