erigon-pulse/erigon-lib/bptree/key_factory.go

/*
   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 bptree

import (
	"bufio"
	"encoding/binary"
	"fmt"
	"io"
	"sort"
)

type KeyFactory interface {
	NewUniqueKeyValues(reader *bufio.Reader) KeyValues
	NewUniqueKeys(reader *bufio.Reader) Keys
}

type KeyBinaryFactory struct {
	keySize int
}

func NewKeyBinaryFactory(keySize int) KeyFactory {
	return &KeyBinaryFactory{keySize: keySize}
}

func (factory *KeyBinaryFactory) NewUniqueKeyValues(reader *bufio.Reader) KeyValues {
	kvPairs := factory.readUniqueKeyValues(reader)
	sort.Sort(kvPairs)
	return kvPairs
}

func (factory *KeyBinaryFactory) NewUniqueKeys(reader *bufio.Reader) Keys {
	keys := factory.readUniqueKeys(reader)
	sort.Sort(keys)
	return keys
}

func (factory *KeyBinaryFactory) readUniqueKeyValues(reader *bufio.Reader) KeyValues {
	kvPairs := KeyValues{make([]*Felt, 0), make([]*Felt, 0)}
	keyRegistry := make(map[Felt]bool)
	buffer := make([]byte, BufferSize)
	for {
		bytesRead, err := reader.Read(buffer)
		ensure(err == nil || err == io.EOF, fmt.Sprintf("readUniqueKeyValues: read error %s\n", err))
		if err == io.EOF {
			break
		}
		keyBytesCount := factory.keySize * (bytesRead / factory.keySize)
		duplicatedKeys := 0
		for i := 0; i < keyBytesCount; i += factory.keySize {
			key := factory.readKey(buffer, i)
			if _, duplicated := keyRegistry[key]; duplicated {
				duplicatedKeys++
				continue
			}
			keyRegistry[key] = true
			value := key // Shortcut: value equal to key
			kvPairs.keys = append(kvPairs.keys, &key)
			kvPairs.values = append(kvPairs.values, &value)
		}
	}
	return kvPairs
}

func (factory *KeyBinaryFactory) readUniqueKeys(reader *bufio.Reader) Keys {
	keys := make(Keys, 0)
	keyRegistry := make(map[Felt]bool)
	buffer := make([]byte, BufferSize)
	for {
		bytesRead, err := reader.Read(buffer)
		if err == io.EOF {
			break
		}
		keyBytesCount := factory.keySize * (bytesRead / factory.keySize)
		duplicatedKeys := 0
		for i := 0; i < keyBytesCount; i += factory.keySize {
			key := factory.readKey(buffer, i)
			if _, duplicated := keyRegistry[key]; duplicated {
				duplicatedKeys++
				continue
			}
			keyRegistry[key] = true
			keys = append(keys, key)
		}
	}
	return keys
}

func (factory *KeyBinaryFactory) readKey(buffer []byte, offset int) Felt {
	keySlice := buffer[offset : offset+factory.keySize]
	switch factory.keySize {
	case 1:
		return Felt(keySlice[0])
	case 2:
		return Felt(binary.BigEndian.Uint16(keySlice))
	case 4:
		return Felt(binary.BigEndian.Uint32(keySlice))
	default:
		return Felt(binary.BigEndian.Uint64(keySlice))
	}
}