lbry-sdk/lbry/wallet/server/db/prefixes.py

import typing
import struct
import array
import base64
import plyvel
from typing import Union, Tuple, NamedTuple, Optional
from lbry.wallet.server.db import DB_PREFIXES
from lbry.wallet.server.db.revertable import RevertableOpStack, RevertablePut, RevertableDelete
from lbry.schema.url import normalize_name

ACTIVATED_CLAIM_TXO_TYPE = 1
ACTIVATED_SUPPORT_TXO_TYPE = 2


def length_encoded_name(name: str) -> bytes:
    encoded = name.encode('utf-8')
    return len(encoded).to_bytes(2, byteorder='big') + encoded


def length_prefix(key: str) -> bytes:
    return len(key).to_bytes(1, byteorder='big') + key.encode()


ROW_TYPES = {}


class PrefixRowType(type):
    def __new__(cls, name, bases, kwargs):
        klass = super().__new__(cls, name, bases, kwargs)
        if name != "PrefixRow":
            ROW_TYPES[klass.prefix] = klass
        return klass


class PrefixRow(metaclass=PrefixRowType):
    prefix: bytes
    key_struct: struct.Struct
    value_struct: struct.Struct
    key_part_lambdas = []

    def __init__(self, db: plyvel.DB, op_stack: RevertableOpStack):
        self._db = db
        self._op_stack = op_stack

    def iterate(self, prefix=None, start=None, stop=None,
                reverse: bool = False, include_key: bool = True, include_value: bool = True):
        if prefix is not None:
            prefix = self.pack_partial_key(*prefix)
        if start is not None:
            start = self.pack_partial_key(*start)
        if stop is not None:
            stop = self.pack_partial_key(*stop)

        if include_key and include_value:
            for k, v in self._db.iterator(prefix=prefix, start=start, stop=stop, reverse=reverse):
                yield self.unpack_key(k), self.unpack_value(v)
        elif include_key:
            for k in self._db.iterator(prefix=prefix, start=start, stop=stop, reverse=reverse, include_value=False):
                yield self.unpack_key(k)
        elif include_value:
            for v in self._db.iterator(prefix=prefix, start=start, stop=stop, reverse=reverse, include_key=False):
                yield self.unpack_value(v)
        else:
            raise RuntimeError

    def get(self, *key_args):
        v = self._db.get(self.pack_key(*key_args))
        if v:
            return self.unpack_value(v)

    def stage_put(self, key_args=(), value_args=()):
        self._op_stack.append_op(RevertablePut(self.pack_key(*key_args), self.pack_value(*value_args)))

    def stage_delete(self, key_args=(), value_args=()):
        self._op_stack.append_op(RevertableDelete(self.pack_key(*key_args), self.pack_value(*value_args)))

    @classmethod
    def pack_partial_key(cls, *args) -> bytes:
        return cls.prefix + cls.key_part_lambdas[len(args)](*args)

    @classmethod
    def pack_key(cls, *args) -> bytes:
        return cls.prefix + cls.key_struct.pack(*args)

    @classmethod
    def pack_value(cls, *args) -> bytes:
        return cls.value_struct.pack(*args)

    @classmethod
    def unpack_key(cls, key: bytes):
        assert key[:1] == cls.prefix
        return cls.key_struct.unpack(key[1:])

    @classmethod
    def unpack_value(cls, data: bytes):
        return cls.value_struct.unpack(data)

    @classmethod
    def unpack_item(cls, key: bytes, value: bytes):
        return cls.unpack_key(key), cls.unpack_value(value)


class UTXOKey(NamedTuple):
    hashX: bytes
    tx_num: int
    nout: int

    def __str__(self):
        return f"{self.__class__.__name__}(hashX={self.hashX.hex()}, tx_num={self.tx_num}, nout={self.nout})"


class UTXOValue(NamedTuple):
    amount: int


class HashXUTXOKey(NamedTuple):
    short_tx_hash: bytes
    tx_num: int
    nout: int

    def __str__(self):
        return f"{self.__class__.__name__}(short_tx_hash={self.short_tx_hash.hex()}, tx_num={self.tx_num}, nout={self.nout})"


class HashXUTXOValue(NamedTuple):
    hashX: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(hashX={self.hashX.hex()})"


class HashXHistoryKey(NamedTuple):
    hashX: bytes
    height: int

    def __str__(self):
        return f"{self.__class__.__name__}(hashX={self.hashX.hex()}, height={self.height})"


class HashXHistoryValue(NamedTuple):
    hashXes: typing.List[int]


class BlockHashKey(NamedTuple):
    height: int


class BlockHashValue(NamedTuple):
    block_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(block_hash={self.block_hash.hex()})"


class TxCountKey(NamedTuple):
    height: int


class TxCountValue(NamedTuple):
    tx_count: int


class TxHashKey(NamedTuple):
    tx_num: int


class TxHashValue(NamedTuple):
    tx_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(tx_hash={self.tx_hash.hex()})"


class TxNumKey(NamedTuple):
    tx_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(tx_hash={self.tx_hash.hex()})"


class TxNumValue(NamedTuple):
    tx_num: int


class TxKey(NamedTuple):
    tx_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(tx_hash={self.tx_hash.hex()})"


class TxValue(NamedTuple):
    raw_tx: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(raw_tx={base64.b64encode(self.raw_tx)})"


class BlockHeaderKey(NamedTuple):
    height: int


class BlockHeaderValue(NamedTuple):
    header: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(header={base64.b64encode(self.header)})"


class ClaimToTXOKey(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class ClaimToTXOValue(typing.NamedTuple):
    tx_num: int
    position: int
    root_tx_num: int
    root_position: int
    amount: int
    # activation: int
    channel_signature_is_valid: bool
    name: str

    @property
    def normalized_name(self) -> str:
        try:
            return normalize_name(self.name)
        except UnicodeDecodeError:
            return self.name


class TXOToClaimKey(typing.NamedTuple):
    tx_num: int
    position: int


class TXOToClaimValue(typing.NamedTuple):
    claim_hash: bytes
    name: str

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, name={self.name})"


class ClaimShortIDKey(typing.NamedTuple):
    normalized_name: str
    partial_claim_id: str
    root_tx_num: int
    root_position: int

    def __str__(self):
        return f"{self.__class__.__name__}(normalized_name={self.normalized_name}, " \
               f"partial_claim_id={self.partial_claim_id}, " \
               f"root_tx_num={self.root_tx_num}, root_position={self.root_position})"


class ClaimShortIDValue(typing.NamedTuple):
    tx_num: int
    position: int


class ClaimToChannelKey(typing.NamedTuple):
    claim_hash: bytes
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, " \
               f"tx_num={self.tx_num}, position={self.position})"


class ClaimToChannelValue(typing.NamedTuple):
    signing_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(signing_hash={self.signing_hash.hex()})"


class ChannelToClaimKey(typing.NamedTuple):
    signing_hash: bytes
    name: str
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(signing_hash={self.signing_hash.hex()}, name={self.name}, " \
               f"tx_num={self.tx_num}, position={self.position})"


class ChannelToClaimValue(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class ClaimToSupportKey(typing.NamedTuple):
    claim_hash: bytes
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, tx_num={self.tx_num}, " \
               f"position={self.position})"


class ClaimToSupportValue(typing.NamedTuple):
    amount: int


class SupportToClaimKey(typing.NamedTuple):
    tx_num: int
    position: int


class SupportToClaimValue(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class ClaimExpirationKey(typing.NamedTuple):
    expiration: int
    tx_num: int
    position: int


class ClaimExpirationValue(typing.NamedTuple):
    claim_hash: bytes
    normalized_name: str

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, normalized_name={self.normalized_name})"


class ClaimTakeoverKey(typing.NamedTuple):
    normalized_name: str


class ClaimTakeoverValue(typing.NamedTuple):
    claim_hash: bytes
    height: int

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, height={self.height})"


class PendingActivationKey(typing.NamedTuple):
    height: int
    txo_type: int
    tx_num: int
    position: int

    @property
    def is_support(self) -> bool:
        return self.txo_type == ACTIVATED_SUPPORT_TXO_TYPE

    @property
    def is_claim(self) -> bool:
        return self.txo_type == ACTIVATED_CLAIM_TXO_TYPE


class PendingActivationValue(typing.NamedTuple):
    claim_hash: bytes
    normalized_name: str

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, normalized_name={self.normalized_name})"


class ActivationKey(typing.NamedTuple):
    txo_type: int
    tx_num: int
    position: int


class ActivationValue(typing.NamedTuple):
    height: int
    claim_hash: bytes
    normalized_name: str

    def __str__(self):
        return f"{self.__class__.__name__}(height={self.height}, claim_hash={self.claim_hash.hex()}, " \
               f"normalized_name={self.normalized_name})"


class ActiveAmountKey(typing.NamedTuple):
    claim_hash: bytes
    txo_type: int
    activation_height: int
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()}, txo_type={self.txo_type}, " \
               f"activation_height={self.activation_height}, tx_num={self.tx_num}, position={self.position})"


class ActiveAmountValue(typing.NamedTuple):
    amount: int


class EffectiveAmountKey(typing.NamedTuple):
    normalized_name: str
    effective_amount: int
    tx_num: int
    position: int


class EffectiveAmountValue(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class RepostKey(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class RepostValue(typing.NamedTuple):
    reposted_claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(reposted_claim_hash={self.reposted_claim_hash.hex()})"


class RepostedKey(typing.NamedTuple):
    reposted_claim_hash: bytes
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(reposted_claim_hash={self.reposted_claim_hash.hex()}, " \
               f"tx_num={self.tx_num}, position={self.position})"


class RepostedValue(typing.NamedTuple):
    claim_hash: bytes

    def __str__(self):
        return f"{self.__class__.__name__}(claim_hash={self.claim_hash.hex()})"


class TouchedOrDeletedClaimKey(typing.NamedTuple):
    height: int


class TouchedOrDeletedClaimValue(typing.NamedTuple):
    touched_claims: typing.Set[bytes]
    deleted_claims: typing.Set[bytes]

    def __str__(self):
        return f"{self.__class__.__name__}(" \
               f"touched_claims={','.join(map(lambda x: x.hex(), self.touched_claims))}," \
               f"deleted_claims={','.join(map(lambda x: x.hex(), self.deleted_claims))})"


class TrendingSpikeKey(typing.NamedTuple):
    height: int
    claim_hash: bytes
    tx_num: int
    position: int

    def __str__(self):
        return f"{self.__class__.__name__}(height={self.height}, claim_hash={self.claim_hash.hex()}, " \
               f"tx_num={self.tx_num}, position={self.position})"


class TrendingSpikeValue(typing.NamedTuple):
    mass: float


class ActiveAmountPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.active_amount.value
    key_struct = struct.Struct(b'>20sBLLH')
    value_struct = struct.Struct(b'>Q')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack,
        struct.Struct(b'>20sB').pack,
        struct.Struct(b'>20sBL').pack,
        struct.Struct(b'>20sBLL').pack,
        struct.Struct(b'>20sBLLH').pack
    ]

    @classmethod
    def pack_key(cls, claim_hash: bytes, txo_type: int, activation_height: int, tx_num: int, position: int):
        return super().pack_key(claim_hash, txo_type, activation_height, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> ActiveAmountKey:
        return ActiveAmountKey(*super().unpack_key(key))

    @classmethod
    def unpack_value(cls, data: bytes) -> ActiveAmountValue:
        return ActiveAmountValue(*super().unpack_value(data))

    @classmethod
    def pack_value(cls, amount: int) -> bytes:
        return cls.value_struct.pack(amount)

    @classmethod
    def pack_item(cls, claim_hash: bytes, txo_type: int, activation_height: int, tx_num: int, position: int, amount: int):
        return cls.pack_key(claim_hash, txo_type, activation_height, tx_num, position), cls.pack_value(amount)


class ClaimToTXOPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_to_txo.value
    key_struct = struct.Struct(b'>20s')
    value_struct = struct.Struct(b'>LHLHQB')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack
    ]

    @classmethod
    def pack_key(cls, claim_hash: bytes):
        return super().pack_key(
            claim_hash
        )

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimToTXOKey:
        assert key[:1] == cls.prefix and len(key) == 21
        return ClaimToTXOKey(key[1:])

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimToTXOValue:
        tx_num, position, root_tx_num, root_position, amount, channel_signature_is_valid = cls.value_struct.unpack(
            data[:21]
        )
        name_len = int.from_bytes(data[21:23], byteorder='big')
        name = data[23:23 + name_len].decode()
        return ClaimToTXOValue(
            tx_num, position, root_tx_num, root_position, amount, bool(channel_signature_is_valid), name
        )

    @classmethod
    def pack_value(cls, tx_num: int, position: int, root_tx_num: int, root_position: int, amount: int,
                   channel_signature_is_valid: bool, name: str) -> bytes:
        return cls.value_struct.pack(
            tx_num, position, root_tx_num, root_position, amount, int(channel_signature_is_valid)
        ) + length_encoded_name(name)

    @classmethod
    def pack_item(cls, claim_hash: bytes, tx_num: int, position: int, root_tx_num: int, root_position: int,
                  amount: int, channel_signature_is_valid: bool, name: str):
        return cls.pack_key(claim_hash), \
               cls.pack_value(tx_num, position, root_tx_num, root_position, amount, channel_signature_is_valid, name)


class TXOToClaimPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.txo_to_claim.value
    key_struct = struct.Struct(b'>LH')
    value_struct = struct.Struct(b'>20s')

    @classmethod
    def pack_key(cls, tx_num: int, position: int):
        return super().pack_key(tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> TXOToClaimKey:
        return TXOToClaimKey(*super().unpack_key(key))

    @classmethod
    def unpack_value(cls, data: bytes) -> TXOToClaimValue:
        claim_hash, = cls.value_struct.unpack(data[:20])
        name_len = int.from_bytes(data[20:22], byteorder='big')
        name = data[22:22 + name_len].decode()
        return TXOToClaimValue(claim_hash, name)

    @classmethod
    def pack_value(cls, claim_hash: bytes, name: str) -> bytes:
        return cls.value_struct.pack(claim_hash) + length_encoded_name(name)

    @classmethod
    def pack_item(cls, tx_num: int, position: int, claim_hash: bytes, name: str):
        return cls.pack_key(tx_num, position), \
               cls.pack_value(claim_hash, name)


def shortid_key_helper(struct_fmt):
    packer = struct.Struct(struct_fmt).pack
    def wrapper(name, *args):
        return length_encoded_name(name) + packer(*args)
    return wrapper


def shortid_key_partial_claim_helper(name: str, partial_claim_id: str):
    assert len(partial_claim_id) < 40
    return length_encoded_name(name) + length_prefix(partial_claim_id)


class ClaimShortIDPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_short_id_prefix.value
    key_struct = struct.Struct(b'>LH')
    value_struct = struct.Struct(b'>LH')
    key_part_lambdas = [
        lambda: b'',
        length_encoded_name,
        shortid_key_partial_claim_helper
    ]

    @classmethod
    def pack_key(cls, name: str, short_claim_id: str, root_tx_num: int, root_position: int):
        return cls.prefix + length_encoded_name(name) + length_prefix(short_claim_id) +\
               cls.key_struct.pack(root_tx_num, root_position)

    @classmethod
    def pack_value(cls, tx_num: int, position: int):
        return super().pack_value(tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimShortIDKey:
        assert key[:1] == cls.prefix
        name_len = int.from_bytes(key[1:3], byteorder='big')
        name = key[3:3 + name_len].decode()
        claim_id_len = int.from_bytes(key[3+name_len:4+name_len], byteorder='big')
        partial_claim_id = key[4+name_len:4+name_len+claim_id_len].decode()
        return ClaimShortIDKey(name, partial_claim_id, *cls.key_struct.unpack(key[4 + name_len + claim_id_len:]))

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimShortIDValue:
        return ClaimShortIDValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, name: str, partial_claim_id: str, root_tx_num: int, root_position: int,
                  tx_num: int, position: int):
        return cls.pack_key(name, partial_claim_id, root_tx_num, root_position), \
               cls.pack_value(tx_num, position)


class ClaimToChannelPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_to_channel.value
    key_struct = struct.Struct(b'>20sLH')
    value_struct = struct.Struct(b'>20s')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack,
        struct.Struct(b'>20sL').pack,
        struct.Struct(b'>20sLH').pack
    ]

    @classmethod
    def pack_key(cls, claim_hash: bytes, tx_num: int, position: int):
        return super().pack_key(claim_hash, tx_num, position)

    @classmethod
    def pack_value(cls, signing_hash: bytes):
        return super().pack_value(signing_hash)

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimToChannelKey:
        return ClaimToChannelKey(*super().unpack_key(key))

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimToChannelValue:
        return ClaimToChannelValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, claim_hash: bytes, tx_num: int, position: int, signing_hash: bytes):
        return cls.pack_key(claim_hash, tx_num, position), cls.pack_value(signing_hash)


def channel_to_claim_helper(struct_fmt):
    packer = struct.Struct(struct_fmt).pack

    def wrapper(signing_hash: bytes, name: str, *args):
        return signing_hash + length_encoded_name(name) + packer(*args)

    return wrapper


class ChannelToClaimPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.channel_to_claim.value
    key_struct = struct.Struct(b'>LH')
    value_struct = struct.Struct(b'>20s')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack,
        channel_to_claim_helper(b''),
        channel_to_claim_helper(b'>s'),
        channel_to_claim_helper(b'>L'),
        channel_to_claim_helper(b'>LH'),
    ]

    @classmethod
    def pack_key(cls, signing_hash: bytes, name: str, tx_num: int, position: int):
        return cls.prefix + signing_hash + length_encoded_name(name) + cls.key_struct.pack(
            tx_num, position
        )

    @classmethod
    def unpack_key(cls, key: bytes) -> ChannelToClaimKey:
        assert key[:1] == cls.prefix
        signing_hash = key[1:21]
        name_len = int.from_bytes(key[21:23], byteorder='big')
        name = key[23:23 + name_len].decode()
        tx_num, position = cls.key_struct.unpack(key[23 + name_len:])
        return ChannelToClaimKey(
            signing_hash, name, tx_num, position
        )

    @classmethod
    def pack_value(cls, claim_hash: bytes) -> bytes:
        return super().pack_value(claim_hash)

    @classmethod
    def unpack_value(cls, data: bytes) -> ChannelToClaimValue:
        return ChannelToClaimValue(*cls.value_struct.unpack(data))

    @classmethod
    def pack_item(cls, signing_hash: bytes, name: str, tx_num: int, position: int,
                  claim_hash: bytes):
        return cls.pack_key(signing_hash, name, tx_num, position), \
               cls.pack_value(claim_hash)


class ClaimToSupportPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_to_support.value
    key_struct = struct.Struct(b'>20sLH')
    value_struct = struct.Struct(b'>Q')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack,
        struct.Struct(b'>20sL').pack,
        struct.Struct(b'>20sLH').pack
    ]

    @classmethod
    def pack_key(cls, claim_hash: bytes, tx_num: int, position: int):
        return super().pack_key(claim_hash, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimToSupportKey:
        return ClaimToSupportKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, amount: int) -> bytes:
        return super().pack_value(amount)

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimToSupportValue:
        return ClaimToSupportValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, claim_hash: bytes, tx_num: int, position: int, amount: int):
        return cls.pack_key(claim_hash, tx_num, position), \
               cls.pack_value(amount)


class SupportToClaimPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.support_to_claim.value
    key_struct = struct.Struct(b'>LH')
    value_struct = struct.Struct(b'>20s')

    @classmethod
    def pack_key(cls, tx_num: int, position: int):
        return super().pack_key(tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> SupportToClaimKey:
        return SupportToClaimKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, claim_hash: bytes) -> bytes:
        return super().pack_value(claim_hash)

    @classmethod
    def unpack_value(cls, data: bytes) -> SupportToClaimValue:
        return SupportToClaimValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, tx_num: int, position: int, claim_hash: bytes):
        return cls.pack_key(tx_num, position), \
               cls.pack_value(claim_hash)


class ClaimExpirationPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_expiration.value
    key_struct = struct.Struct(b'>LLH')
    value_struct = struct.Struct(b'>20s')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>L').pack,
        struct.Struct(b'>LL').pack,
        struct.Struct(b'>LLH').pack,
    ]

    @classmethod
    def pack_key(cls, expiration: int, tx_num: int, position: int) -> bytes:
        return super().pack_key(expiration, tx_num, position)

    @classmethod
    def pack_value(cls, claim_hash: bytes, name: str) -> bytes:
        return cls.value_struct.pack(claim_hash) + length_encoded_name(name)

    @classmethod
    def pack_item(cls, expiration: int, tx_num: int, position: int, claim_hash: bytes, name: str) -> typing.Tuple[bytes, bytes]:
        return cls.pack_key(expiration, tx_num, position), cls.pack_value(claim_hash, name)

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimExpirationKey:
        return ClaimExpirationKey(*super().unpack_key(key))

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimExpirationValue:
        name_len = int.from_bytes(data[20:22], byteorder='big')
        name = data[22:22 + name_len].decode()
        claim_id, = cls.value_struct.unpack(data[:20])
        return ClaimExpirationValue(claim_id, name)

    @classmethod
    def unpack_item(cls, key: bytes, value: bytes) -> typing.Tuple[ClaimExpirationKey, ClaimExpirationValue]:
        return cls.unpack_key(key), cls.unpack_value(value)


class ClaimTakeoverPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_takeover.value
    value_struct = struct.Struct(b'>20sL')

    @classmethod
    def pack_key(cls, name: str):
        return cls.prefix + length_encoded_name(name)

    @classmethod
    def pack_value(cls, claim_hash: bytes, takeover_height: int):
        return super().pack_value(claim_hash, takeover_height)

    @classmethod
    def unpack_key(cls, key: bytes) -> ClaimTakeoverKey:
        assert key[:1] == cls.prefix
        name_len = int.from_bytes(key[1:3], byteorder='big')
        name = key[3:3 + name_len].decode()
        return ClaimTakeoverKey(name)

    @classmethod
    def unpack_value(cls, data: bytes) -> ClaimTakeoverValue:
        return ClaimTakeoverValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, name: str, claim_hash: bytes, takeover_height: int):
        return cls.pack_key(name), cls.pack_value(claim_hash, takeover_height)


class PendingActivationPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.pending_activation.value
    key_struct = struct.Struct(b'>LBLH')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>L').pack,
        struct.Struct(b'>LB').pack,
        struct.Struct(b'>LBL').pack,
        struct.Struct(b'>LBLH').pack
    ]

    @classmethod
    def pack_key(cls, height: int, txo_type: int, tx_num: int, position: int):
        return super().pack_key(height, txo_type, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> PendingActivationKey:
        return PendingActivationKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, claim_hash: bytes, name: str) -> bytes:
        return claim_hash + length_encoded_name(name)

    @classmethod
    def unpack_value(cls, data: bytes) -> PendingActivationValue:
        claim_hash = data[:20]
        name_len = int.from_bytes(data[20:22], byteorder='big')
        name = data[22:22 + name_len].decode()
        return PendingActivationValue(claim_hash, name)

    @classmethod
    def pack_item(cls, height: int, txo_type: int, tx_num: int, position: int, claim_hash: bytes, name: str):
        return cls.pack_key(height, txo_type, tx_num, position), \
               cls.pack_value(claim_hash, name)


class ActivatedPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.activated_claim_and_support.value
    key_struct = struct.Struct(b'>BLH')
    value_struct = struct.Struct(b'>L20s')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>B').pack,
        struct.Struct(b'>BL').pack,
        struct.Struct(b'>BLH').pack
    ]

    @classmethod
    def pack_key(cls, txo_type: int, tx_num: int, position: int):
        return super().pack_key(txo_type, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> ActivationKey:
        return ActivationKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, height: int, claim_hash: bytes, name: str) -> bytes:
        return cls.value_struct.pack(height, claim_hash) + length_encoded_name(name)

    @classmethod
    def unpack_value(cls, data: bytes) -> ActivationValue:
        height, claim_hash = cls.value_struct.unpack(data[:24])
        name_len = int.from_bytes(data[24:26], byteorder='big')
        name = data[26:26 + name_len].decode()
        return ActivationValue(height, claim_hash, name)

    @classmethod
    def pack_item(cls, txo_type: int, tx_num: int, position: int, height: int, claim_hash: bytes, name: str):
        return cls.pack_key(txo_type, tx_num, position), \
               cls.pack_value(height, claim_hash, name)


def effective_amount_helper(struct_fmt):
    packer = struct.Struct(struct_fmt).pack

    def wrapper(name, *args):
        if not args:
            return length_encoded_name(name)
        if len(args) == 1:
            return length_encoded_name(name) + packer(0xffffffffffffffff - args[0])
        return length_encoded_name(name) + packer(0xffffffffffffffff - args[0], *args[1:])

    return wrapper


class EffectiveAmountPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.effective_amount.value
    key_struct = struct.Struct(b'>QLH')
    value_struct = struct.Struct(b'>20s')
    key_part_lambdas = [
        lambda: b'',
        length_encoded_name,
        shortid_key_helper(b'>Q'),
        shortid_key_helper(b'>QL'),
        shortid_key_helper(b'>QLH'),
    ]

    @classmethod
    def pack_key(cls, name: str, effective_amount: int, tx_num: int, position: int):
        return cls.prefix + length_encoded_name(name) + cls.key_struct.pack(
                    0xffffffffffffffff - effective_amount, tx_num, position
        )

    @classmethod
    def unpack_key(cls, key: bytes) -> EffectiveAmountKey:
        assert key[:1] == cls.prefix
        name_len = int.from_bytes(key[1:3], byteorder='big')
        name = key[3:3 + name_len].decode()
        ones_comp_effective_amount, tx_num, position = cls.key_struct.unpack(key[3 + name_len:])
        return EffectiveAmountKey(name, 0xffffffffffffffff - ones_comp_effective_amount, tx_num, position)

    @classmethod
    def unpack_value(cls, data: bytes) -> EffectiveAmountValue:
        return EffectiveAmountValue(*super().unpack_value(data))

    @classmethod
    def pack_value(cls, claim_hash: bytes) -> bytes:
        return super().pack_value(claim_hash)

    @classmethod
    def pack_item(cls, name: str, effective_amount: int, tx_num: int, position: int, claim_hash: bytes):
        return cls.pack_key(name, effective_amount, tx_num, position), cls.pack_value(claim_hash)


class RepostPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.repost.value

    @classmethod
    def pack_key(cls, claim_hash: bytes):
        return cls.prefix + claim_hash

    @classmethod
    def unpack_key(cls, key: bytes) -> RepostKey:
        assert key[:1] == cls.prefix
        assert len(key) == 21
        return RepostKey(key[1:])

    @classmethod
    def pack_value(cls, reposted_claim_hash: bytes) -> bytes:
        return reposted_claim_hash

    @classmethod
    def unpack_value(cls, data: bytes) -> RepostValue:
        return RepostValue(data)

    @classmethod
    def pack_item(cls, claim_hash: bytes, reposted_claim_hash: bytes):
        return cls.pack_key(claim_hash), cls.pack_value(reposted_claim_hash)


class RepostedPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.reposted_claim.value
    key_struct = struct.Struct(b'>20sLH')
    value_struct = struct.Struct(b'>20s')
    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>20s').pack,
        struct.Struct(b'>20sL').pack,
        struct.Struct(b'>20sLH').pack
    ]

    @classmethod
    def pack_key(cls, reposted_claim_hash: bytes, tx_num: int, position: int):
        return super().pack_key(reposted_claim_hash, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> RepostedKey:
        return RepostedKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, claim_hash: bytes) -> bytes:
        return super().pack_value(claim_hash)

    @classmethod
    def unpack_value(cls, data: bytes) -> RepostedValue:
        return RepostedValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, reposted_claim_hash: bytes, tx_num: int, position: int, claim_hash: bytes):
        return cls.pack_key(reposted_claim_hash, tx_num, position), cls.pack_value(claim_hash)


class UndoPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.undo.value
    key_struct = struct.Struct(b'>Q')

    @classmethod
    def pack_key(cls, height: int):
        return super().pack_key(height)

    @classmethod
    def unpack_key(cls, key: bytes) -> int:
        assert key[:1] == cls.prefix
        height, = cls.key_struct.unpack(key[1:])
        return height

    @classmethod
    def pack_value(cls, undo_ops: bytes) -> bytes:
        return undo_ops

    @classmethod
    def unpack_value(cls, data: bytes) -> bytes:
        return data

    @classmethod
    def pack_item(cls, height: int, undo_ops: bytes):
        return cls.pack_key(height), cls.pack_value(undo_ops)


class BlockHashPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.block_hash.value
    key_struct = struct.Struct(b'>L')
    value_struct = struct.Struct(b'>32s')

    @classmethod
    def pack_key(cls, height: int) -> bytes:
        return super().pack_key(height)

    @classmethod
    def unpack_key(cls, key: bytes) -> BlockHashKey:
        return BlockHashKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, block_hash: bytes) -> bytes:
        return super().pack_value(block_hash)

    @classmethod
    def unpack_value(cls, data: bytes) -> BlockHashValue:
        return BlockHashValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, height: int, block_hash: bytes):
        return cls.pack_key(height), cls.pack_value(block_hash)


class BlockHeaderPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.header.value
    key_struct = struct.Struct(b'>L')
    value_struct = struct.Struct(b'>112s')

    @classmethod
    def pack_key(cls, height: int) -> bytes:
        return super().pack_key(height)

    @classmethod
    def unpack_key(cls, key: bytes) -> BlockHeaderKey:
        return BlockHeaderKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, header: bytes) -> bytes:
        return super().pack_value(header)

    @classmethod
    def unpack_value(cls, data: bytes) -> BlockHeaderValue:
        return BlockHeaderValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, height: int, header: bytes):
        return cls.pack_key(height), cls.pack_value(header)


class TXNumPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.tx_num.value
    key_struct = struct.Struct(b'>32s')
    value_struct = struct.Struct(b'>L')

    @classmethod
    def pack_key(cls, tx_hash: bytes) -> bytes:
        return super().pack_key(tx_hash)

    @classmethod
    def unpack_key(cls, tx_hash: bytes) -> TxNumKey:
        return TxNumKey(*super().unpack_key(tx_hash))

    @classmethod
    def pack_value(cls, tx_num: int) -> bytes:
        return super().pack_value(tx_num)

    @classmethod
    def unpack_value(cls, data: bytes) -> TxNumValue:
        return TxNumValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, tx_hash: bytes, tx_num: int):
        return cls.pack_key(tx_hash), cls.pack_value(tx_num)


class TxCountPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.tx_count.value
    key_struct = struct.Struct(b'>L')
    value_struct = struct.Struct(b'>L')

    @classmethod
    def pack_key(cls, height: int) -> bytes:
        return super().pack_key(height)

    @classmethod
    def unpack_key(cls, key: bytes) -> TxCountKey:
        return TxCountKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, tx_count: int) -> bytes:
        return super().pack_value(tx_count)

    @classmethod
    def unpack_value(cls, data: bytes) -> TxCountValue:
        return TxCountValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, height: int, tx_count: int):
        return cls.pack_key(height), cls.pack_value(tx_count)


class TXHashPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.tx_hash.value
    key_struct = struct.Struct(b'>L')
    value_struct = struct.Struct(b'>32s')

    @classmethod
    def pack_key(cls, tx_num: int) -> bytes:
        return super().pack_key(tx_num)

    @classmethod
    def unpack_key(cls, key: bytes) -> TxHashKey:
        return TxHashKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, tx_hash: bytes) -> bytes:
        return super().pack_value(tx_hash)

    @classmethod
    def unpack_value(cls, data: bytes) -> TxHashValue:
        return TxHashValue(*super().unpack_value(data))

    @classmethod
    def pack_item(cls, tx_num: int, tx_hash: bytes):
        return cls.pack_key(tx_num), cls.pack_value(tx_hash)


class TXPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.tx.value
    key_struct = struct.Struct(b'>32s')

    @classmethod
    def pack_key(cls, tx_hash: bytes) -> bytes:
        return super().pack_key(tx_hash)

    @classmethod
    def unpack_key(cls, tx_hash: bytes) -> TxKey:
        return TxKey(*super().unpack_key(tx_hash))

    @classmethod
    def pack_value(cls, tx: bytes) -> bytes:
        return tx

    @classmethod
    def unpack_value(cls, data: bytes) -> TxValue:
        return TxValue(data)

    @classmethod
    def pack_item(cls, tx_hash: bytes, raw_tx: bytes):
        return cls.pack_key(tx_hash), cls.pack_value(raw_tx)


class UTXOPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.utxo.value
    key_struct = struct.Struct(b'>11sLH')
    value_struct = struct.Struct(b'>Q')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>11s').pack,
        struct.Struct(b'>11sL').pack,
        struct.Struct(b'>11sLH').pack
    ]

    @classmethod
    def pack_key(cls, hashX: bytes, tx_num, nout: int):
        return super().pack_key(hashX, tx_num, nout)

    @classmethod
    def unpack_key(cls, key: bytes) -> UTXOKey:
        return UTXOKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, amount: int) -> bytes:
        return super().pack_value(amount)

    @classmethod
    def unpack_value(cls, data: bytes) -> UTXOValue:
        return UTXOValue(*cls.value_struct.unpack(data))

    @classmethod
    def pack_item(cls, hashX: bytes, tx_num: int, nout: int, amount: int):
        return cls.pack_key(hashX, tx_num, nout), cls.pack_value(amount)


class HashXUTXOPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.hashx_utxo.value
    key_struct = struct.Struct(b'>4sLH')
    value_struct = struct.Struct(b'>11s')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>4s').pack,
        struct.Struct(b'>4sL').pack,
        struct.Struct(b'>4sLH').pack
    ]

    @classmethod
    def pack_key(cls, short_tx_hash: bytes, tx_num, nout: int):
        return super().pack_key(short_tx_hash, tx_num, nout)

    @classmethod
    def unpack_key(cls, key: bytes) -> HashXUTXOKey:
        return HashXUTXOKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, hashX: bytes) -> bytes:
        return super().pack_value(hashX)

    @classmethod
    def unpack_value(cls, data: bytes) -> HashXUTXOValue:
        return HashXUTXOValue(*cls.value_struct.unpack(data))

    @classmethod
    def pack_item(cls, short_tx_hash: bytes, tx_num: int, nout: int, hashX: bytes):
        return cls.pack_key(short_tx_hash, tx_num, nout), cls.pack_value(hashX)


class HashXHistoryPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.hashx_history.value
    key_struct = struct.Struct(b'>11sL')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>11s').pack
    ]

    @classmethod
    def pack_key(cls, hashX: bytes, height: int):
        return super().pack_key(hashX, height)

    @classmethod
    def unpack_key(cls, key: bytes) -> HashXHistoryKey:
        return HashXHistoryKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, history: typing.List[int]) -> bytes:
        a = array.array('I')
        a.fromlist(history)
        return a.tobytes()

    @classmethod
    def unpack_value(cls, data: bytes) -> HashXHistoryValue:
        a = array.array('I')
        a.frombytes(data)
        return HashXHistoryValue(a.tolist())

    @classmethod
    def pack_item(cls, hashX: bytes, height: int, history: typing.List[int]):
        return cls.pack_key(hashX, height), cls.pack_value(history)


class TouchedOrDeletedPrefixRow(PrefixRow):
    prefix = DB_PREFIXES.claim_diff.value
    key_struct = struct.Struct(b'>L')
    value_struct = struct.Struct(b'>LL')

    @classmethod
    def pack_key(cls, height: int):
        return super().pack_key(height)

    @classmethod
    def unpack_key(cls, key: bytes) -> TouchedOrDeletedClaimKey:
        return TouchedOrDeletedClaimKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, touched, deleted) -> bytes:
        return cls.value_struct.pack(len(touched), len(deleted)) + b''.join(touched) + b''.join(deleted)

    @classmethod
    def unpack_value(cls, data: bytes) -> TouchedOrDeletedClaimValue:
        touched_len, deleted_len = cls.value_struct.unpack(data[:8])
        assert len(data) == 20 * (touched_len + deleted_len) + 8
        touched_bytes, deleted_bytes = data[8:touched_len*20+8], data[touched_len*20+8:touched_len*20+deleted_len*20+8]
        return TouchedOrDeletedClaimValue(
            {touched_bytes[8+20*i:8+20*(i+1)] for i in range(touched_len)},
            {deleted_bytes[8+20*i:8+20*(i+1)] for i in range(deleted_len)}
        )

    @classmethod
    def pack_item(cls, height, touched, deleted):
        return cls.pack_key(height), cls.pack_value(touched, deleted)


class TrendingSpikePrefixRow(PrefixRow):
    prefix = DB_PREFIXES.trending_spike.value
    key_struct = struct.Struct(b'>L20sLH')
    value_struct = struct.Struct(b'>f')

    key_part_lambdas = [
        lambda: b'',
        struct.Struct(b'>L').pack,
        struct.Struct(b'>L20s').pack,
        struct.Struct(b'>L20sL').pack,
        struct.Struct(b'>L20sLH').pack
    ]

    @classmethod
    def pack_spike(cls, height: int, claim_hash: bytes, tx_num: int, position: int, amount: int, half_life: int,
                   depth: int = 0, subtract: bool = False) -> RevertablePut:
        softened_change = (((amount * 1E-8) + 1E-8) ** (1 / 4))
        spike_mass = softened_change * ((2.0 ** (-1 / half_life)) ** depth)
        if subtract:
            spike_mass = -spike_mass
        return RevertablePut(*cls.pack_item(height, claim_hash, tx_num, position, spike_mass))

    @classmethod
    def pack_key(cls, height: int, claim_hash: bytes, tx_num: int, position: int):
        return super().pack_key(height, claim_hash, tx_num, position)

    @classmethod
    def unpack_key(cls, key: bytes) -> TrendingSpikeKey:
        return TrendingSpikeKey(*super().unpack_key(key))

    @classmethod
    def pack_value(cls, mass: float) -> bytes:
        return super().pack_value(mass)

    @classmethod
    def unpack_value(cls, data: bytes) -> TrendingSpikeValue:
        return TrendingSpikeValue(*cls.value_struct.unpack(data))

    @classmethod
    def pack_item(cls, height: int, claim_hash: bytes, tx_num: int, position: int, mass: float):
        return cls.pack_key(height, claim_hash, tx_num, position), cls.pack_value(mass)


class Prefixes:
    claim_to_support = ClaimToSupportPrefixRow
    support_to_claim = SupportToClaimPrefixRow

    claim_to_txo = ClaimToTXOPrefixRow
    txo_to_claim = TXOToClaimPrefixRow

    claim_to_channel = ClaimToChannelPrefixRow
    channel_to_claim = ChannelToClaimPrefixRow

    claim_short_id = ClaimShortIDPrefixRow
    claim_expiration = ClaimExpirationPrefixRow

    claim_takeover = ClaimTakeoverPrefixRow
    pending_activation = PendingActivationPrefixRow
    activated = ActivatedPrefixRow
    active_amount = ActiveAmountPrefixRow

    effective_amount = EffectiveAmountPrefixRow

    repost = RepostPrefixRow
    reposted_claim = RepostedPrefixRow

    undo = UndoPrefixRow
    utxo = UTXOPrefixRow
    hashX_utxo = HashXUTXOPrefixRow
    hashX_history = HashXHistoryPrefixRow
    block_hash = BlockHashPrefixRow
    tx_count = TxCountPrefixRow
    tx_hash = TXHashPrefixRow
    tx_num = TXNumPrefixRow
    tx = TXPrefixRow
    header = BlockHeaderPrefixRow
    touched_or_deleted = TouchedOrDeletedPrefixRow
    trending_spike = TrendingSpikePrefixRow


class PrefixDB:
    def __init__(self, db: plyvel.DB, op_stack: RevertableOpStack):
        self._db = db
        self._op_stack = op_stack

        self.claim_to_support = ClaimToSupportPrefixRow(db, op_stack)
        self.support_to_claim = SupportToClaimPrefixRow(db, op_stack)
        self.claim_to_txo = ClaimToTXOPrefixRow(db, op_stack)
        self.txo_to_claim = TXOToClaimPrefixRow(db, op_stack)
        self.claim_to_channel = ClaimToChannelPrefixRow(db, op_stack)
        self.channel_to_claim = ChannelToClaimPrefixRow(db, op_stack)
        self.claim_short_id = ClaimShortIDPrefixRow(db, op_stack)
        self.claim_expiration = ClaimExpirationPrefixRow(db, op_stack)
        self.claim_takeover = ClaimTakeoverPrefixRow(db, op_stack)
        self.pending_activation = PendingActivationPrefixRow(db, op_stack)
        self.activated = ActivatedPrefixRow(db, op_stack)
        self.active_amount = ActiveAmountPrefixRow(db, op_stack)
        self.effective_amount = EffectiveAmountPrefixRow(db, op_stack)
        self.repost = RepostPrefixRow(db, op_stack)
        self.reposted_claim = RepostedPrefixRow(db, op_stack)
        self.undo = UndoPrefixRow(db, op_stack)
        self.utxo = UTXOPrefixRow(db, op_stack)
        self.hashX_utxo = HashXUTXOPrefixRow(db, op_stack)
        self.hashX_history = HashXHistoryPrefixRow(db, op_stack)
        self.block_hash = BlockHashPrefixRow(db, op_stack)
        self.tx_count = TxCountPrefixRow(db, op_stack)
        self.tx_hash = TXHashPrefixRow(db, op_stack)
        self.tx_num = TXNumPrefixRow(db, op_stack)
        self.tx = TXPrefixRow(db, op_stack)
        self.header = BlockHeaderPrefixRow(db, op_stack)
        self.touched_or_deleted = TouchedOrDeletedPrefixRow(db, op_stack)
        self.trending_spike = TrendingSpikePrefixRow(db, op_stack)

    def commit(self):
        try:
            with self._db.write_batch(transaction=True) as batch:
                batch_put = batch.put
                batch_delete = batch.delete

                for staged_change in self._op_stack:
                    if staged_change.is_put:
                        batch_put(staged_change.key, staged_change.value)
                    else:
                        batch_delete(staged_change.key)
        finally:
            self._op_stack.clear()


def auto_decode_item(key: bytes, value: bytes) -> Union[Tuple[NamedTuple, NamedTuple], Tuple[bytes, bytes]]:
    try:
        return ROW_TYPES[key[:1]].unpack_item(key, value)
    except KeyError:
        return key, value