lbry-sdk/lbry/wallet/server/block_processor.py

import time
import asyncio
import typing
import signal

from bisect import bisect_right
from struct import pack
from concurrent.futures.thread import ThreadPoolExecutor
from typing import Optional, List, Tuple, Set, DefaultDict, Dict
from prometheus_client import Gauge, Histogram
from collections import defaultdict

import lbry
from lbry.schema.claim import Claim
from lbry.wallet.ledger import Ledger, TestNetLedger, RegTestLedger
from lbry.utils import LRUCache
from lbry.wallet.transaction import OutputScript, Output, Transaction
from lbry.wallet.server.tx import Tx, TxOutput, TxInput
from lbry.wallet.server.hash import hash_to_hex_str
from lbry.wallet.server.util import class_logger
from lbry.crypto.hash import hash160
from lbry.wallet.server.db.prefixes import ACTIVATED_SUPPORT_TXO_TYPE, ACTIVATED_CLAIM_TXO_TYPE
from lbry.wallet.server.db.prefixes import PendingActivationKey, PendingActivationValue, ClaimToTXOValue
from lbry.wallet.server.prefetcher import Prefetcher
from lbry.wallet.server.db.db import HubDB

if typing.TYPE_CHECKING:
    from lbry.wallet.server.db.revertable import RevertableOpStack


class ChainError(Exception):
    """Raised on error processing blocks."""


class StagedClaimtrieItem(typing.NamedTuple):
    name: str
    normalized_name: str
    claim_hash: bytes
    amount: int
    expiration_height: int
    tx_num: int
    position: int
    root_tx_num: int
    root_position: int
    channel_signature_is_valid: bool
    signing_hash: Optional[bytes]
    reposted_claim_hash: Optional[bytes]

    @property
    def is_update(self) -> bool:
        return (self.tx_num, self.position) != (self.root_tx_num, self.root_position)

    def invalidate_signature(self) -> 'StagedClaimtrieItem':
        return StagedClaimtrieItem(
            self.name, self.normalized_name, self.claim_hash, self.amount, self.expiration_height, self.tx_num,
            self.position, self.root_tx_num, self.root_position, False, None, self.reposted_claim_hash
        )


NAMESPACE = "wallet_server"
HISTOGRAM_BUCKETS = (
    .005, .01, .025, .05, .075, .1, .25, .5, .75, 1.0, 2.5, 5.0, 7.5, 10.0, 15.0, 20.0, 30.0, 60.0, float('inf')
)


class BlockProcessor:
    """Process blocks and update the DB state to match.

    Employ a prefetcher to prefetch blocks in batches for processing.
    Coordinate backing up in case of chain reorganisations.
    """

    block_count_metric = Gauge(
        "block_count", "Number of processed blocks", namespace=NAMESPACE
    )
    block_update_time_metric = Histogram(
        "block_time", "Block update times", namespace=NAMESPACE, buckets=HISTOGRAM_BUCKETS
    )
    reorg_count_metric = Gauge(
        "reorg_count", "Number of reorgs", namespace=NAMESPACE
    )

    def __init__(self, env: 'Env'):
        self.cancellable_tasks = []

        self.env = env
        self.state_lock = asyncio.Lock()
        self.daemon = env.coin.DAEMON(env.coin, env.daemon_url)
        self.db = HubDB(
            env.coin, env.db_dir, env.cache_MB, env.reorg_limit, env.cache_all_claim_txos, env.cache_all_tx_hashes,
            max_open_files=env.db_max_open_files
        )
        self._chain_executor = ThreadPoolExecutor(1, thread_name_prefix='block-processor')
        self._sync_reader_executor = ThreadPoolExecutor(1, thread_name_prefix='hub-es-sync')
        self.shutdown_event = asyncio.Event()
        self.coin = env.coin
        if env.coin.NET == 'mainnet':
            self.ledger = Ledger
        elif env.coin.NET == 'testnet':
            self.ledger = TestNetLedger
        else:
            self.ledger = RegTestLedger

        self._caught_up_event: Optional[asyncio.Event] = None
        self.height = 0
        self.tip = bytes.fromhex(self.coin.GENESIS_HASH)[::-1]
        self.tx_count = 0

        self.blocks_event = asyncio.Event()
        self.prefetcher = Prefetcher(self.daemon, env.coin, self.blocks_event)
        self.logger = class_logger(__name__, self.__class__.__name__)

        # Meta
        self.touched_hashXs: Set[bytes] = set()

        # UTXO cache
        self.utxo_cache: Dict[Tuple[bytes, int], Tuple[bytes, int]] = {}

        # Claimtrie cache
        self.db_op_stack: Optional['RevertableOpStack'] = None

        # self.search_cache = {}
        self.resolve_cache = LRUCache(2**16)
        self.resolve_outputs_cache = LRUCache(2 ** 16)

        self.history_cache = {}

        #################################
        # attributes used for calculating stake activations and takeovers per block
        #################################

        self.taken_over_names: Set[str] = set()
        # txo to pending claim
        self.txo_to_claim: Dict[Tuple[int, int], StagedClaimtrieItem] = {}
        # claim hash to pending claim txo
        self.claim_hash_to_txo: Dict[bytes, Tuple[int, int]] = {}
        # claim hash to lists of pending support txos
        self.support_txos_by_claim: DefaultDict[bytes, List[Tuple[int, int]]] = defaultdict(list)
        # support txo: (supported claim hash, support amount)
        self.support_txo_to_claim: Dict[Tuple[int, int], Tuple[bytes, int]] = {}
        # removed supports {name: {claim_hash: [(tx_num, nout), ...]}}
        self.removed_support_txos_by_name_by_claim: DefaultDict[str, DefaultDict[bytes, List[Tuple[int, int]]]] = \
            defaultdict(lambda: defaultdict(list))
        self.abandoned_claims: Dict[bytes, StagedClaimtrieItem] = {}
        self.updated_claims: Set[bytes] = set()
        # removed activated support amounts by claim hash
        self.removed_active_support_amount_by_claim: DefaultDict[bytes, List[int]] = defaultdict(list)
        # pending activated support amounts by claim hash
        self.activated_support_amount_by_claim: DefaultDict[bytes, List[int]] = defaultdict(list)
        # pending activated name and claim hash to claim/update txo amount
        self.activated_claim_amount_by_name_and_hash: Dict[Tuple[str, bytes], int] = {}
        # pending claim and support activations per claim hash per name,
        # used to process takeovers due to added activations
        activation_by_claim_by_name_type = DefaultDict[str, DefaultDict[bytes, List[Tuple[PendingActivationKey, int]]]]
        self.activation_by_claim_by_name: activation_by_claim_by_name_type = defaultdict(lambda: defaultdict(list))
        # these are used for detecting early takeovers by not yet activated claims/supports
        self.possible_future_support_amounts_by_claim_hash: DefaultDict[bytes, List[int]] = defaultdict(list)
        self.possible_future_claim_amount_by_name_and_hash: Dict[Tuple[str, bytes], int] = {}
        self.possible_future_support_txos_by_claim_hash: DefaultDict[bytes, List[Tuple[int, int]]] = defaultdict(list)

        self.removed_claims_to_send_es = set()  # cumulative changes across blocks to send ES
        self.touched_claims_to_send_es = set()

        self.removed_claim_hashes: Set[bytes] = set()  # per block changes
        self.touched_claim_hashes: Set[bytes] = set()

        self.signatures_changed = set()

        self.pending_reposted = set()
        self.pending_channel_counts = defaultdict(lambda: 0)
        self.pending_support_amount_change = defaultdict(lambda: 0)

        self.pending_channels = {}
        self.amount_cache = {}
        self.expired_claim_hashes: Set[bytes] = set()

        self.doesnt_have_valid_signature: Set[bytes] = set()
        self.claim_channels: Dict[bytes, bytes] = {}
        self.hashXs_by_tx: DefaultDict[bytes, List[int]] = defaultdict(list)

        self.pending_transaction_num_mapping: Dict[bytes, int] = {}
        self.pending_transactions: Dict[int, bytes] = {}

    async def claim_producer(self):
        if self.db.db_height <= 1:
            return

        for claim_hash in self.removed_claims_to_send_es:
            yield 'delete', claim_hash.hex()

        to_update = await asyncio.get_event_loop().run_in_executor(
            self._sync_reader_executor, self.db.claims_producer, self.touched_claims_to_send_es
        )
        for claim in to_update:
            yield 'update', claim

    async def run_in_thread_with_lock(self, func, *args):
        # Run in a thread to prevent blocking.  Shielded so that
        # cancellations from shutdown don't lose work - when the task
        # completes the data will be flushed and then we shut down.
        # Take the state lock to be certain in-memory state is
        # consistent and not being updated elsewhere.
        async def run_in_thread_locked():
            async with self.state_lock:
                return await asyncio.get_event_loop().run_in_executor(self._chain_executor, func, *args)
        return await asyncio.shield(run_in_thread_locked())

    async def run_in_thread(self, func, *args):
        async def run_in_thread():
            return await asyncio.get_event_loop().run_in_executor(self._chain_executor, func, *args)
        return await asyncio.shield(run_in_thread())

    async def check_mempool(self):
        if self.db.prefix_db.closed:
            return
        current_mempool = {
            k.tx_hash: v.raw_tx for (k, v) in self.db.prefix_db.mempool_tx.iterate()
        }
        for hh in await self.daemon.mempool_hashes():
            tx_hash = bytes.fromhex(hh)[::-1]
            if tx_hash in current_mempool:
                current_mempool.pop(tx_hash)
            else:
                raw_tx = bytes.fromhex(await self.daemon.getrawtransaction(hh))
                self.db.prefix_db.mempool_tx.stage_put((tx_hash,), (raw_tx,))
        for tx_hash, raw_tx in current_mempool.items():
            self.db.prefix_db.mempool_tx.stage_delete((tx_hash,), (raw_tx,))

    async def check_and_advance_blocks(self, raw_blocks):
        """Process the list of raw blocks passed.  Detects and handles
        reorgs.
        """

        if not raw_blocks:
            return
        first = self.height + 1
        blocks = [self.coin.block(raw_block, first + n)
                  for n, raw_block in enumerate(raw_blocks)]
        headers = [block.header for block in blocks]
        hprevs = [self.coin.header_prevhash(h) for h in headers]
        chain = [self.tip] + [self.coin.header_hash(h) for h in headers[:-1]]

        if hprevs == chain:
            total_start = time.perf_counter()
            try:
                for block in blocks:
                    start = time.perf_counter()
                    await self.run_in_thread(self.advance_block, block)
                    await self.flush()

                    self.logger.warning("writer advanced to %i in %0.3fs", self.height, time.perf_counter() - start)
                    if self.height == self.coin.nExtendedClaimExpirationForkHeight:
                        self.logger.warning(
                            "applying extended claim expiration fork on claims accepted by, %i", self.height
                        )
                        await self.run_in_thread_with_lock(self.db.apply_expiration_extension_fork)
                # print("******************\n")
            except:
                self.logger.exception("advance blocks failed")
                raise
            processed_time = time.perf_counter() - total_start
            self.block_count_metric.set(self.height)
            self.block_update_time_metric.observe(processed_time)
            if not self.db.first_sync:
                s = '' if len(blocks) == 1 else 's'
                self.logger.info('processed {:,d} block{} in {:.1f}s'.format(len(blocks), s, processed_time))
            self.touched_hashXs.clear()
        elif hprevs[0] != chain[0]:
            min_start_height = max(self.height - self.coin.REORG_LIMIT, 0)
            count = 1
            block_hashes_from_lbrycrd = await self.daemon.block_hex_hashes(
                min_start_height, self.coin.REORG_LIMIT
            )
            for height, block_hash in zip(
                    reversed(range(min_start_height, min_start_height + self.coin.REORG_LIMIT)),
                    reversed(block_hashes_from_lbrycrd)):
                if self.db.get_block_hash(height)[::-1].hex() == block_hash:
                    break
                count += 1
            self.logger.warning(f"blockchain reorg detected at {self.height}, unwinding last {count} blocks")
            try:
                assert count > 0, count
                for _ in range(count):
                    await self.backup_block()
                    self.logger.info(f'backed up to height {self.height:,d}')

                    if self.env.cache_all_claim_txos:
                        await self.db._read_claim_txos()  # TODO: don't do this
                await self.prefetcher.reset_height(self.height)
                self.reorg_count_metric.inc()
            except:
                self.logger.exception("reorg blocks failed")
                raise
            finally:
                self.logger.info("backed up to block %i", self.height)
        else:
            # It is probably possible but extremely rare that what
            # bitcoind returns doesn't form a chain because it
            # reorg-ed the chain as it was processing the batched
            # block hash requests.  Should this happen it's simplest
            # just to reset the prefetcher and try again.
            self.logger.warning('daemon blocks do not form a chain; '
                                'resetting the prefetcher')
            await self.prefetcher.reset_height(self.height)

    async def flush(self):
        save_undo = (self.daemon.cached_height() - self.height) <= self.env.reorg_limit

        def flush():
            self.db.write_db_state()
            if save_undo:
                self.db.prefix_db.commit(self.height, self.tip)
            else:
                self.db.prefix_db.unsafe_commit()
            self.clear_after_advance_or_reorg()
            self.db.assert_db_state()
        await self.run_in_thread_with_lock(flush)

    def _add_claim_or_update(self, height: int, txo: 'Output', tx_hash: bytes, tx_num: int, nout: int,
                             spent_claims: typing.Dict[bytes, typing.Tuple[int, int, str]]):
        try:
            claim_name = txo.script.values['claim_name'].decode()
        except UnicodeDecodeError:
            claim_name = ''.join(chr(c) for c in txo.script.values['claim_name'])
        try:
            normalized_name = txo.normalized_name
        except UnicodeDecodeError:
            normalized_name = claim_name
        if txo.script.is_claim_name:
            claim_hash = hash160(tx_hash + pack('>I', nout))[::-1]
            # print(f"\tnew {claim_hash.hex()} ({tx_num} {txo.amount})")
        else:
            claim_hash = txo.claim_hash[::-1]
            # print(f"\tupdate {claim_hash.hex()} ({tx_num} {txo.amount})")

        signing_channel_hash = None
        channel_signature_is_valid = False
        try:
            signable = txo.signable
            is_repost = txo.claim.is_repost
            is_channel = txo.claim.is_channel
            if txo.claim.is_signed:
                signing_channel_hash = txo.signable.signing_channel_hash[::-1]
        except:  # google.protobuf.message.DecodeError: Could not parse JSON.
            signable = None
            is_repost = False
            is_channel = False

        reposted_claim_hash = None

        if is_repost:
            reposted_claim_hash = txo.claim.repost.reference.claim_hash[::-1]
            self.pending_reposted.add(reposted_claim_hash)

        if is_channel:
            self.pending_channels[claim_hash] = txo.claim.channel.public_key_bytes

        self.doesnt_have_valid_signature.add(claim_hash)
        raw_channel_tx = None
        if signable and signable.signing_channel_hash:
            signing_channel = self.db.get_claim_txo(signing_channel_hash)

            if signing_channel:
                raw_channel_tx = self.db.prefix_db.tx.get(
                    self.db.get_tx_hash(signing_channel.tx_num), deserialize_value=False
                )
            channel_pub_key_bytes = None
            try:
                if not signing_channel:
                    if txo.signable.signing_channel_hash[::-1] in self.pending_channels:
                        channel_pub_key_bytes = self.pending_channels[signing_channel_hash]
                elif raw_channel_tx:
                    chan_output = self.coin.transaction(raw_channel_tx).outputs[signing_channel.position]
                    chan_script = OutputScript(chan_output.pk_script)
                    chan_script.parse()
                    channel_meta = Claim.from_bytes(chan_script.values['claim'])

                    channel_pub_key_bytes = channel_meta.channel.public_key_bytes
                if channel_pub_key_bytes:
                    channel_signature_is_valid = Output.is_signature_valid(
                        txo.signable.signature, txo.get_signature_digest(self.ledger), channel_pub_key_bytes
                    )
                    if channel_signature_is_valid:
                        self.pending_channel_counts[signing_channel_hash] += 1
                        self.doesnt_have_valid_signature.remove(claim_hash)
                        self.claim_channels[claim_hash] = signing_channel_hash
            except:
                self.logger.exception(f"error validating channel signature for %s:%i", tx_hash[::-1].hex(), nout)

        if txo.script.is_claim_name:  # it's a root claim
            root_tx_num, root_idx = tx_num, nout
            previous_amount = 0
        else:  # it's a claim update
            if claim_hash not in spent_claims:
                # print(f"\tthis is a wonky tx, contains unlinked claim update {claim_hash.hex()}")
                return
            if normalized_name != spent_claims[claim_hash][2]:
                self.logger.warning(
                    f"{tx_hash[::-1].hex()} contains mismatched name for claim update {claim_hash.hex()}"
                )
                return
            (prev_tx_num, prev_idx, _) = spent_claims.pop(claim_hash)
            # print(f"\tupdate {claim_hash.hex()} {tx_hash[::-1].hex()} {txo.amount}")
            if (prev_tx_num, prev_idx) in self.txo_to_claim:
                previous_claim = self.txo_to_claim.pop((prev_tx_num, prev_idx))
                self.claim_hash_to_txo.pop(claim_hash)
                root_tx_num, root_idx = previous_claim.root_tx_num, previous_claim.root_position
            else:
                previous_claim = self._make_pending_claim_txo(claim_hash)
                root_tx_num, root_idx = previous_claim.root_tx_num, previous_claim.root_position
                activation = self.db.get_activation(prev_tx_num, prev_idx)
                claim_name = previous_claim.name
                self.get_remove_activate_ops(
                    ACTIVATED_CLAIM_TXO_TYPE, claim_hash, prev_tx_num, prev_idx, activation, normalized_name,
                    previous_claim.amount
                )
            previous_amount = previous_claim.amount
            self.updated_claims.add(claim_hash)

        if self.env.cache_all_claim_txos:
            self.db.claim_to_txo[claim_hash] = ClaimToTXOValue(
                tx_num, nout, root_tx_num, root_idx, txo.amount, channel_signature_is_valid, claim_name
            )
            self.db.txo_to_claim[tx_num][nout] = claim_hash

        pending = StagedClaimtrieItem(
            claim_name, normalized_name, claim_hash, txo.amount, self.coin.get_expiration_height(height), tx_num, nout,
            root_tx_num, root_idx, channel_signature_is_valid, signing_channel_hash, reposted_claim_hash
        )
        self.txo_to_claim[(tx_num, nout)] = pending
        self.claim_hash_to_txo[claim_hash] = (tx_num, nout)
        self.get_add_claim_utxo_ops(pending)

    def get_add_claim_utxo_ops(self, pending: StagedClaimtrieItem):
        # claim tip by claim hash
        self.db.prefix_db.claim_to_txo.stage_put(
            (pending.claim_hash,), (pending.tx_num, pending.position, pending.root_tx_num, pending.root_position,
                                    pending.amount, pending.channel_signature_is_valid, pending.name)
        )
        # claim hash by txo
        self.db.prefix_db.txo_to_claim.stage_put(
            (pending.tx_num, pending.position), (pending.claim_hash, pending.normalized_name)
        )

        # claim expiration
        self.db.prefix_db.claim_expiration.stage_put(
            (pending.expiration_height, pending.tx_num, pending.position),
            (pending.claim_hash, pending.normalized_name)
        )

        # short url resolution
        for prefix_len in range(10):
            self.db.prefix_db.claim_short_id.stage_put(
                (pending.normalized_name, pending.claim_hash.hex()[:prefix_len + 1],
                 pending.root_tx_num, pending.root_position),
                (pending.tx_num, pending.position)
            )

        if pending.signing_hash and pending.channel_signature_is_valid:
            # channel by stream
            self.db.prefix_db.claim_to_channel.stage_put(
                (pending.claim_hash, pending.tx_num, pending.position), (pending.signing_hash,)
            )
            # stream by channel
            self.db.prefix_db.channel_to_claim.stage_put(
                (pending.signing_hash, pending.normalized_name, pending.tx_num, pending.position),
                (pending.claim_hash,)
            )

        if pending.reposted_claim_hash:
            self.db.prefix_db.repost.stage_put((pending.claim_hash,), (pending.reposted_claim_hash,))
            self.db.prefix_db.reposted_claim.stage_put(
                (pending.reposted_claim_hash, pending.tx_num, pending.position), (pending.claim_hash,)
            )

    def get_remove_claim_utxo_ops(self, pending: StagedClaimtrieItem):
        # claim tip by claim hash
        self.db.prefix_db.claim_to_txo.stage_delete(
            (pending.claim_hash,), (pending.tx_num, pending.position, pending.root_tx_num, pending.root_position,
                                    pending.amount, pending.channel_signature_is_valid, pending.name)
        )
        # claim hash by txo
        self.db.prefix_db.txo_to_claim.stage_delete(
            (pending.tx_num, pending.position), (pending.claim_hash, pending.normalized_name)
        )

        # claim expiration
        self.db.prefix_db.claim_expiration.stage_delete(
            (pending.expiration_height, pending.tx_num, pending.position),
            (pending.claim_hash, pending.normalized_name)
        )

        # short url resolution
        for prefix_len in range(10):
            self.db.prefix_db.claim_short_id.stage_delete(
                (pending.normalized_name, pending.claim_hash.hex()[:prefix_len + 1],
                 pending.root_tx_num, pending.root_position),
                (pending.tx_num, pending.position)
            )

        if pending.signing_hash and pending.channel_signature_is_valid:
            # channel by stream
            self.db.prefix_db.claim_to_channel.stage_delete(
                (pending.claim_hash, pending.tx_num, pending.position), (pending.signing_hash,)
            )
            # stream by channel
            self.db.prefix_db.channel_to_claim.stage_delete(
                (pending.signing_hash, pending.normalized_name, pending.tx_num, pending.position),
                (pending.claim_hash,)
            )

        if pending.reposted_claim_hash:
            self.db.prefix_db.repost.stage_delete((pending.claim_hash,), (pending.reposted_claim_hash,))
            self.db.prefix_db.reposted_claim.stage_delete(
                (pending.reposted_claim_hash, pending.tx_num, pending.position), (pending.claim_hash,)
            )

    def _add_support(self, height: int, txo: 'Output', tx_num: int, nout: int):
        supported_claim_hash = txo.claim_hash[::-1]
        self.support_txos_by_claim[supported_claim_hash].append((tx_num, nout))
        self.support_txo_to_claim[(tx_num, nout)] = supported_claim_hash, txo.amount
        # print(f"\tsupport claim {supported_claim_hash.hex()} +{txo.amount}")

        self.db.prefix_db.claim_to_support.stage_put((supported_claim_hash, tx_num, nout), (txo.amount,))
        self.db.prefix_db.support_to_claim.stage_put((tx_num, nout), (supported_claim_hash,))
        self.pending_support_amount_change[supported_claim_hash] += txo.amount

    def _add_claim_or_support(self, height: int, tx_hash: bytes, tx_num: int, nout: int, txo: 'Output',
                              spent_claims: typing.Dict[bytes, Tuple[int, int, str]]):
        if txo.script.is_claim_name or txo.script.is_update_claim:
            self._add_claim_or_update(height, txo, tx_hash, tx_num, nout, spent_claims)
        elif txo.script.is_support_claim or txo.script.is_support_claim_data:
            self._add_support(height, txo, tx_num, nout)

    def _spend_support_txo(self, height: int, txin: TxInput):
        txin_num = self.get_pending_tx_num(txin.prev_hash)
        activation = 0
        if (txin_num, txin.prev_idx) in self.support_txo_to_claim:
            spent_support, support_amount = self.support_txo_to_claim.pop((txin_num, txin.prev_idx))
            self.support_txos_by_claim[spent_support].remove((txin_num, txin.prev_idx))
            supported_name = self._get_pending_claim_name(spent_support)
            self.removed_support_txos_by_name_by_claim[supported_name][spent_support].append((txin_num, txin.prev_idx))
        else:
            spent_support, support_amount = self.db.get_supported_claim_from_txo(txin_num, txin.prev_idx)
            if not spent_support:  # it is not a support
                return
            supported_name = self._get_pending_claim_name(spent_support)
            if supported_name is not None:
                self.removed_support_txos_by_name_by_claim[supported_name][spent_support].append(
                    (txin_num, txin.prev_idx))
            activation = self.db.get_activation(txin_num, txin.prev_idx, is_support=True)
            if 0 < activation < self.height + 1:
                self.removed_active_support_amount_by_claim[spent_support].append(support_amount)
            if supported_name is not None and activation > 0:
                self.get_remove_activate_ops(
                    ACTIVATED_SUPPORT_TXO_TYPE, spent_support, txin_num, txin.prev_idx, activation, supported_name,
                    support_amount
                )
        # print(f"\tspent support for {spent_support.hex()} activation:{activation} {support_amount}")
        self.db.prefix_db.claim_to_support.stage_delete((spent_support, txin_num, txin.prev_idx), (support_amount,))
        self.db.prefix_db.support_to_claim.stage_delete((txin_num, txin.prev_idx), (spent_support,))
        self.pending_support_amount_change[spent_support] -= support_amount

    def _spend_claim_txo(self, txin: TxInput, spent_claims: Dict[bytes, Tuple[int, int, str]]) -> bool:
        txin_num = self.get_pending_tx_num(txin.prev_hash)
        if (txin_num, txin.prev_idx) in self.txo_to_claim:
            spent = self.txo_to_claim[(txin_num, txin.prev_idx)]
        else:
            if not self.db.get_cached_claim_exists(txin_num, txin.prev_idx):
                # txo is not a claim
                return False
            spent_claim_hash_and_name = self.db.get_claim_from_txo(
                txin_num, txin.prev_idx
            )
            assert spent_claim_hash_and_name is not None
            spent = self._make_pending_claim_txo(spent_claim_hash_and_name.claim_hash)

        if self.env.cache_all_claim_txos:
            claim_hash = self.db.txo_to_claim[txin_num].pop(txin.prev_idx)
            if not self.db.txo_to_claim[txin_num]:
                self.db.txo_to_claim.pop(txin_num)
            self.db.claim_to_txo.pop(claim_hash)
        if spent.reposted_claim_hash:
            self.pending_reposted.add(spent.reposted_claim_hash)
        if spent.signing_hash and spent.channel_signature_is_valid and spent.signing_hash not in self.abandoned_claims:
            self.pending_channel_counts[spent.signing_hash] -= 1
        spent_claims[spent.claim_hash] = (spent.tx_num, spent.position, spent.normalized_name)
        # print(f"\tspend lbry://{spent.name}#{spent.claim_hash.hex()}")
        self.get_remove_claim_utxo_ops(spent)
        return True

    def _spend_claim_or_support_txo(self, height: int, txin: TxInput, spent_claims):
        if not self._spend_claim_txo(txin, spent_claims):
            self._spend_support_txo(height, txin)

    def _abandon_claim(self, claim_hash: bytes, tx_num: int, nout: int, normalized_name: str):
        if (tx_num, nout) in self.txo_to_claim:
            pending = self.txo_to_claim.pop((tx_num, nout))
            self.claim_hash_to_txo.pop(claim_hash)
            self.abandoned_claims[pending.claim_hash] = pending
            claim_root_tx_num, claim_root_idx = pending.root_tx_num, pending.root_position
            prev_amount, prev_signing_hash = pending.amount, pending.signing_hash
            reposted_claim_hash, name = pending.reposted_claim_hash, pending.name
            expiration = self.coin.get_expiration_height(self.height)
            signature_is_valid = pending.channel_signature_is_valid
        else:
            v = self.db.get_claim_txo(
                claim_hash
            )
            claim_root_tx_num, claim_root_idx, prev_amount = v.root_tx_num,  v.root_position, v.amount
            signature_is_valid, name = v.channel_signature_is_valid, v.name
            prev_signing_hash = self.db.get_channel_for_claim(claim_hash, tx_num, nout)
            reposted_claim_hash = self.db.get_repost(claim_hash)
            expiration = self.coin.get_expiration_height(bisect_right(self.db.tx_counts, tx_num))
        self.abandoned_claims[claim_hash] = staged = StagedClaimtrieItem(
            name, normalized_name, claim_hash, prev_amount, expiration, tx_num, nout, claim_root_tx_num,
            claim_root_idx, signature_is_valid, prev_signing_hash, reposted_claim_hash
        )
        for support_txo_to_clear in self.support_txos_by_claim[claim_hash]:
            self.support_txo_to_claim.pop(support_txo_to_clear)
        self.support_txos_by_claim[claim_hash].clear()
        self.support_txos_by_claim.pop(claim_hash)
        if normalized_name.startswith('@'):  # abandon a channel, invalidate signatures
            self._invalidate_channel_signatures(claim_hash)

    def _get_invalidate_signature_ops(self, pending: StagedClaimtrieItem):
        if not pending.signing_hash:
            return
        self.db.prefix_db.claim_to_channel.stage_delete(
            (pending.claim_hash, pending.tx_num, pending.position), (pending.signing_hash,)
        )
        if pending.channel_signature_is_valid:
            self.db.prefix_db.channel_to_claim.stage_delete(
                (pending.signing_hash, pending.normalized_name, pending.tx_num, pending.position),
                (pending.claim_hash,)
            )
            self.db.prefix_db.claim_to_txo.stage_delete(
                (pending.claim_hash,),
                (pending.tx_num, pending.position, pending.root_tx_num, pending.root_position, pending.amount,
                 pending.channel_signature_is_valid, pending.name)
            )
            self.db.prefix_db.claim_to_txo.stage_put(
                (pending.claim_hash,),
                (pending.tx_num, pending.position, pending.root_tx_num, pending.root_position, pending.amount,
                 False, pending.name)
            )

    def _invalidate_channel_signatures(self, claim_hash: bytes):
        for (signed_claim_hash, ) in self.db.prefix_db.channel_to_claim.iterate(
                prefix=(claim_hash, ), include_key=False):
            if signed_claim_hash in self.abandoned_claims or signed_claim_hash in self.expired_claim_hashes:
                continue
            # there is no longer a signing channel for this claim as of this block
            if signed_claim_hash in self.doesnt_have_valid_signature:
                continue
            # the signing channel changed in this block
            if signed_claim_hash in self.claim_channels and signed_claim_hash != self.claim_channels[signed_claim_hash]:
                continue

            # if the claim with an invalidated signature is in this block, update the StagedClaimtrieItem
            # so that if we later try to spend it in this block we won't try to delete the channel info twice
            if signed_claim_hash in self.claim_hash_to_txo:
                signed_claim_txo = self.claim_hash_to_txo[signed_claim_hash]
                claim = self.txo_to_claim[signed_claim_txo]
                if claim.signing_hash != claim_hash:  # claim was already invalidated this block
                    continue
                self.txo_to_claim[signed_claim_txo] = claim.invalidate_signature()
            else:
                claim = self._make_pending_claim_txo(signed_claim_hash)
            self.signatures_changed.add(signed_claim_hash)
            self.pending_channel_counts[claim_hash] -= 1
            self._get_invalidate_signature_ops(claim)

        for staged in list(self.txo_to_claim.values()):
            needs_invalidate = staged.claim_hash not in self.doesnt_have_valid_signature
            if staged.signing_hash == claim_hash and needs_invalidate:
                self._get_invalidate_signature_ops(staged)
                self.txo_to_claim[self.claim_hash_to_txo[staged.claim_hash]] = staged.invalidate_signature()
                self.signatures_changed.add(staged.claim_hash)
                self.pending_channel_counts[claim_hash] -= 1

    def _make_pending_claim_txo(self, claim_hash: bytes):
        claim = self.db.get_claim_txo(claim_hash)
        if claim_hash in self.doesnt_have_valid_signature:
            signing_hash = None
        else:
            signing_hash = self.db.get_channel_for_claim(claim_hash, claim.tx_num, claim.position)
        reposted_claim_hash = self.db.get_repost(claim_hash)
        return StagedClaimtrieItem(
            claim.name, claim.normalized_name, claim_hash, claim.amount,
            self.coin.get_expiration_height(
                bisect_right(self.db.tx_counts, claim.tx_num),
                extended=self.height >= self.coin.nExtendedClaimExpirationForkHeight
            ),
            claim.tx_num, claim.position, claim.root_tx_num, claim.root_position,
            claim.channel_signature_is_valid, signing_hash, reposted_claim_hash
        )

    def _expire_claims(self, height: int):
        expired = self.db.get_expired_by_height(height)
        self.expired_claim_hashes.update(set(expired.keys()))
        spent_claims = {}
        for expired_claim_hash, (tx_num, position, name, txi) in expired.items():
            if (tx_num, position) not in self.txo_to_claim:
                self._spend_claim_txo(txi, spent_claims)
        if expired:
            # abandon the channels last to handle abandoned signed claims in the same tx,
            # see test_abandon_channel_and_claims_in_same_tx
            expired_channels = {}
            for abandoned_claim_hash, (tx_num, nout, normalized_name) in spent_claims.items():
                self._abandon_claim(abandoned_claim_hash, tx_num, nout, normalized_name)

                if normalized_name.startswith('@'):
                    expired_channels[abandoned_claim_hash] = (tx_num, nout, normalized_name)
                else:
                    # print(f"\texpire {abandoned_claim_hash.hex()} {tx_num} {nout}")
                    self._abandon_claim(abandoned_claim_hash, tx_num, nout, normalized_name)

            # do this to follow the same content claim removing pathway as if a claim (possible channel) was abandoned
            for abandoned_claim_hash, (tx_num, nout, normalized_name) in expired_channels.items():
                # print(f"\texpire {abandoned_claim_hash.hex()} {tx_num} {nout}")
                self._abandon_claim(abandoned_claim_hash, tx_num, nout, normalized_name)

    def _cached_get_active_amount(self, claim_hash: bytes, txo_type: int, height: int) -> int:
        if (claim_hash, txo_type, height) in self.amount_cache:
            return self.amount_cache[(claim_hash, txo_type, height)]
        if txo_type == ACTIVATED_CLAIM_TXO_TYPE:
            if claim_hash in self.claim_hash_to_txo:
                amount = self.txo_to_claim[self.claim_hash_to_txo[claim_hash]].amount
            else:
                amount = self.db.get_active_amount_as_of_height(
                    claim_hash, height
                )
            self.amount_cache[(claim_hash, txo_type, height)] = amount
        else:
            self.amount_cache[(claim_hash, txo_type, height)] = amount = self.db._get_active_amount(
                claim_hash, txo_type, height
            )
        return amount

    def _get_pending_claim_amount(self, name: str, claim_hash: bytes, height=None) -> int:
        if (name, claim_hash) in self.activated_claim_amount_by_name_and_hash:
            if claim_hash in self.claim_hash_to_txo:
                return self.txo_to_claim[self.claim_hash_to_txo[claim_hash]].amount
            return self.activated_claim_amount_by_name_and_hash[(name, claim_hash)]
        if (name, claim_hash) in self.possible_future_claim_amount_by_name_and_hash:
            return self.possible_future_claim_amount_by_name_and_hash[(name, claim_hash)]
        return self._cached_get_active_amount(claim_hash, ACTIVATED_CLAIM_TXO_TYPE, height or (self.height + 1))

    def _get_pending_claim_name(self, claim_hash: bytes) -> Optional[str]:
        assert claim_hash is not None
        if claim_hash in self.claim_hash_to_txo:
            return self.txo_to_claim[self.claim_hash_to_txo[claim_hash]].normalized_name
        claim_info = self.db.get_claim_txo(claim_hash)
        if claim_info:
            return claim_info.normalized_name

    def _get_pending_supported_amount(self, claim_hash: bytes, height: Optional[int] = None) -> int:
        amount = self._cached_get_active_amount(claim_hash, ACTIVATED_SUPPORT_TXO_TYPE, height or (self.height + 1))
        if claim_hash in self.activated_support_amount_by_claim:
            amount += sum(self.activated_support_amount_by_claim[claim_hash])
        if claim_hash in self.possible_future_support_amounts_by_claim_hash:
            amount += sum(self.possible_future_support_amounts_by_claim_hash[claim_hash])
        if claim_hash in self.removed_active_support_amount_by_claim:
            return amount - sum(self.removed_active_support_amount_by_claim[claim_hash])
        return amount

    def _get_pending_effective_amount(self, name: str, claim_hash: bytes, height: Optional[int] = None) -> int:
        claim_amount = self._get_pending_claim_amount(name, claim_hash, height=height)
        support_amount = self._get_pending_supported_amount(claim_hash, height=height)
        return claim_amount + support_amount

    def get_activate_ops(self, txo_type: int, claim_hash: bytes, tx_num: int, position: int,
                          activation_height: int, name: str, amount: int):
        self.db.prefix_db.activated.stage_put(
            (txo_type, tx_num, position), (activation_height, claim_hash, name)
        )
        self.db.prefix_db.pending_activation.stage_put(
            (activation_height, txo_type, tx_num, position), (claim_hash, name)
        )
        self.db.prefix_db.active_amount.stage_put(
            (claim_hash, txo_type, activation_height, tx_num, position), (amount,)
        )

    def get_remove_activate_ops(self, txo_type: int, claim_hash: bytes, tx_num: int, position: int,
                                activation_height: int, name: str, amount: int):
        self.db.prefix_db.activated.stage_delete(
            (txo_type, tx_num, position), (activation_height, claim_hash, name)
        )
        self.db.prefix_db.pending_activation.stage_delete(
            (activation_height, txo_type, tx_num, position), (claim_hash, name)
        )
        self.db.prefix_db.active_amount.stage_delete(
            (claim_hash, txo_type, activation_height, tx_num, position), (amount,)
        )

    def _get_takeover_ops(self, height: int):

        # cache for controlling claims as of the previous block
        controlling_claims = {}

        def get_controlling(_name):
            if _name not in controlling_claims:
                _controlling = self.db.get_controlling_claim(_name)
                controlling_claims[_name] = _controlling
            else:
                _controlling = controlling_claims[_name]
            return _controlling

        names_with_abandoned_or_updated_controlling_claims: List[str] = []

        # get the claims and supports previously scheduled to be activated at this block
        activated_at_height = self.db.get_activated_at_height(height)
        activate_in_future = defaultdict(lambda: defaultdict(list))
        future_activations = defaultdict(dict)

        def get_delayed_activate_ops(name: str, claim_hash: bytes, is_new_claim: bool, tx_num: int, nout: int,
                                     amount: int, is_support: bool):
            controlling = get_controlling(name)
            nothing_is_controlling = not controlling
            staged_is_controlling = False if not controlling else claim_hash == controlling.claim_hash
            controlling_is_abandoned = False if not controlling else \
                name in names_with_abandoned_or_updated_controlling_claims

            if nothing_is_controlling or staged_is_controlling or controlling_is_abandoned:
                delay = 0
            elif is_new_claim:
                delay = self.coin.get_delay_for_name(height - controlling.height)
            else:
                controlling_effective_amount = self._get_pending_effective_amount(name, controlling.claim_hash)
                staged_effective_amount = self._get_pending_effective_amount(name, claim_hash)
                staged_update_could_cause_takeover = staged_effective_amount > controlling_effective_amount
                delay = 0 if not staged_update_could_cause_takeover else self.coin.get_delay_for_name(
                    height - controlling.height
                )
            if delay == 0:  # if delay was 0 it needs to be considered for takeovers
                activated_at_height[PendingActivationValue(claim_hash, name)].append(
                    PendingActivationKey(
                        height, ACTIVATED_SUPPORT_TXO_TYPE if is_support else ACTIVATED_CLAIM_TXO_TYPE, tx_num, nout
                    )
                )
            else:  # if the delay was higher if still needs to be considered if something else triggers a takeover
                activate_in_future[name][claim_hash].append((
                    PendingActivationKey(
                        height + delay, ACTIVATED_SUPPORT_TXO_TYPE if is_support else ACTIVATED_CLAIM_TXO_TYPE,
                        tx_num, nout
                    ), amount
                ))
                if is_support:
                    self.possible_future_support_txos_by_claim_hash[claim_hash].append((tx_num, nout))
            self.get_activate_ops(
                ACTIVATED_SUPPORT_TXO_TYPE if is_support else ACTIVATED_CLAIM_TXO_TYPE, claim_hash, tx_num, nout,
                height + delay, name, amount
            )

        # determine names needing takeover/deletion due to controlling claims being abandoned
        # and add ops to deactivate abandoned claims
        for claim_hash, staged in self.abandoned_claims.items():
            controlling = get_controlling(staged.normalized_name)
            if controlling and controlling.claim_hash == claim_hash:
                names_with_abandoned_or_updated_controlling_claims.append(staged.normalized_name)
                # print(f"\t{staged.name} needs takeover")
            activation = self.db.get_activation(staged.tx_num, staged.position)
            if activation > 0:  #  db returns -1 for non-existent txos
                # removed queued future activation from the db
                self.get_remove_activate_ops(
                    ACTIVATED_CLAIM_TXO_TYPE, staged.claim_hash, staged.tx_num, staged.position,
                    activation, staged.normalized_name, staged.amount
                )
            else:
                # it hadn't yet been activated
                pass

        # get the removed activated supports for controlling claims to determine if takeovers are possible
        abandoned_support_check_need_takeover = defaultdict(list)
        for claim_hash, amounts in self.removed_active_support_amount_by_claim.items():
            name = self._get_pending_claim_name(claim_hash)
            if name is None:
                continue
            controlling = get_controlling(name)
            if controlling and controlling.claim_hash == claim_hash and \
                    name not in names_with_abandoned_or_updated_controlling_claims:
                abandoned_support_check_need_takeover[(name, claim_hash)].extend(amounts)

        # get the controlling claims with updates to the claim to check if takeover is needed
        for claim_hash in self.updated_claims:
            if claim_hash in self.abandoned_claims:
                continue
            name = self._get_pending_claim_name(claim_hash)
            if name is None:
                continue
            controlling = get_controlling(name)
            if controlling and controlling.claim_hash == claim_hash and \
                    name not in names_with_abandoned_or_updated_controlling_claims:
                names_with_abandoned_or_updated_controlling_claims.append(name)

        # prepare to activate or delay activation of the pending claims being added this block
        for (tx_num, nout), staged in self.txo_to_claim.items():
            is_delayed = not staged.is_update
            prev_txo = self.db.get_cached_claim_txo(staged.claim_hash)
            if prev_txo:
                prev_activation = self.db.get_activation(prev_txo.tx_num, prev_txo.position)
                if height < prev_activation or prev_activation < 0:
                    is_delayed = True
            get_delayed_activate_ops(
                staged.normalized_name, staged.claim_hash, is_delayed, tx_num, nout, staged.amount,
                is_support=False
            )

        # and the supports
        for (tx_num, nout), (claim_hash, amount) in self.support_txo_to_claim.items():
            if claim_hash in self.abandoned_claims:
                continue
            elif claim_hash in self.claim_hash_to_txo:
                name = self.txo_to_claim[self.claim_hash_to_txo[claim_hash]].normalized_name
                staged_is_new_claim = not self.txo_to_claim[self.claim_hash_to_txo[claim_hash]].is_update
            else:
                supported_claim_info = self.db.get_claim_txo(claim_hash)
                if not supported_claim_info:
                    # the supported claim doesn't exist
                    continue
                else:
                    v = supported_claim_info
                name = v.normalized_name
                staged_is_new_claim = (v.root_tx_num, v.root_position) == (v.tx_num, v.position)
            get_delayed_activate_ops(
                name, claim_hash, staged_is_new_claim, tx_num, nout, amount, is_support=True
            )

        # add the activation/delayed-activation ops
        for activated, activated_txos in activated_at_height.items():
            controlling = get_controlling(activated.normalized_name)
            if activated.claim_hash in self.abandoned_claims:
                continue
            reactivate = False
            if not controlling or controlling.claim_hash == activated.claim_hash:
                # there is no delay for claims to a name without a controlling value or to the controlling value
                reactivate = True
            for activated_txo in activated_txos:
                if activated_txo.is_support and (activated_txo.tx_num, activated_txo.position) in \
                        self.removed_support_txos_by_name_by_claim[activated.normalized_name][activated.claim_hash]:
                    # print("\tskip activate support for pending abandoned claim")
                    continue
                if activated_txo.is_claim:
                    txo_type = ACTIVATED_CLAIM_TXO_TYPE
                    txo_tup = (activated_txo.tx_num, activated_txo.position)
                    if txo_tup in self.txo_to_claim:
                        amount = self.txo_to_claim[txo_tup].amount
                    else:
                        amount = self.db.get_claim_txo_amount(
                            activated.claim_hash
                        )
                    if amount is None:
                        # print("\tskip activate for non existent claim")
                        continue
                    self.activated_claim_amount_by_name_and_hash[(activated.normalized_name, activated.claim_hash)] = amount
                else:
                    txo_type = ACTIVATED_SUPPORT_TXO_TYPE
                    txo_tup = (activated_txo.tx_num, activated_txo.position)
                    if txo_tup in self.support_txo_to_claim:
                        amount = self.support_txo_to_claim[txo_tup][1]
                    else:
                        amount = self.db.get_support_txo_amount(
                            activated.claim_hash, activated_txo.tx_num, activated_txo.position
                        )
                    if amount is None:
                        # print("\tskip activate support for non existent claim")
                        continue
                    self.activated_support_amount_by_claim[activated.claim_hash].append(amount)
                self.activation_by_claim_by_name[activated.normalized_name][activated.claim_hash].append((activated_txo, amount))
                # print(f"\tactivate {'support' if txo_type == ACTIVATED_SUPPORT_TXO_TYPE else 'claim'} "
                #       f"{activated.claim_hash.hex()} @ {activated_txo.height}")

        # go through claims where the controlling claim or supports to the controlling claim have been abandoned
        # check if takeovers are needed or if the name node is now empty
        need_reactivate_if_takes_over = {}
        for need_takeover in names_with_abandoned_or_updated_controlling_claims:
            existing = self.db.get_claim_txos_for_name(need_takeover)
            has_candidate = False
            # add existing claims to the queue for the takeover
            # track that we need to reactivate these if one of them becomes controlling
            for candidate_claim_hash, (tx_num, nout) in existing.items():
                if candidate_claim_hash in self.abandoned_claims:
                    continue
                has_candidate = True
                existing_activation = self.db.get_activation(tx_num, nout)
                activate_key = PendingActivationKey(
                    existing_activation, ACTIVATED_CLAIM_TXO_TYPE, tx_num, nout
                )
                self.activation_by_claim_by_name[need_takeover][candidate_claim_hash].append((
                    activate_key, self.db.get_claim_txo_amount(candidate_claim_hash)
                ))
                need_reactivate_if_takes_over[(need_takeover, candidate_claim_hash)] = activate_key
                # print(f"\tcandidate to takeover abandoned controlling claim for "
                #       f"{activate_key.tx_num}:{activate_key.position} {activate_key.is_claim}")
            if not has_candidate:
                # remove name takeover entry, the name is now unclaimed
                controlling = get_controlling(need_takeover)
                self.db.prefix_db.claim_takeover.stage_delete(
                    (need_takeover,), (controlling.claim_hash, controlling.height)
                )

        # scan for possible takeovers out of the accumulated activations, of these make sure there
        # aren't any future activations for the taken over names with yet higher amounts, if there are
        # these need to get activated now and take over instead. for example:
        # claim A is winning for 0.1 for long enough for a > 1 takeover delay
        # claim B is made for 0.2
        # a block later, claim C is made for 0.3, it will schedule to activate 1 (or rarely 2) block(s) after B
        # upon the delayed activation of B, we need to detect to activate C and make it take over early instead

        claim_exists = {}
        for activated, activated_claim_txo in self.db.get_future_activated(height).items():
            # uses the pending effective amount for the future activation height, not the current height
            future_amount = self._get_pending_claim_amount(
                activated.normalized_name, activated.claim_hash, activated_claim_txo.height + 1
            )
            if activated.claim_hash not in claim_exists:
                claim_exists[activated.claim_hash] = activated.claim_hash in self.claim_hash_to_txo or (
                        self.db.get_claim_txo(activated.claim_hash) is not None)
            if claim_exists[activated.claim_hash] and activated.claim_hash not in self.abandoned_claims:
                v = future_amount, activated, activated_claim_txo
                future_activations[activated.normalized_name][activated.claim_hash] = v

        for name, future_activated in activate_in_future.items():
            for claim_hash, activated in future_activated.items():
                if claim_hash not in claim_exists:
                    claim_exists[claim_hash] = claim_hash in self.claim_hash_to_txo or (
                            self.db.get_claim_txo(claim_hash) is not None)
                if not claim_exists[claim_hash]:
                    continue
                if claim_hash in self.abandoned_claims:
                    continue
                for txo in activated:
                    v = txo[1], PendingActivationValue(claim_hash, name), txo[0]
                    future_activations[name][claim_hash] = v
                    if txo[0].is_claim:
                        self.possible_future_claim_amount_by_name_and_hash[(name, claim_hash)] = txo[1]
                    else:
                        self.possible_future_support_amounts_by_claim_hash[claim_hash].append(txo[1])

        # process takeovers
        checked_names = set()
        for name, activated in self.activation_by_claim_by_name.items():
            checked_names.add(name)
            controlling = controlling_claims[name]
            amounts = {
                claim_hash: self._get_pending_effective_amount(name, claim_hash)
                for claim_hash in activated.keys() if claim_hash not in self.abandoned_claims
            }
            # if there is a controlling claim include it in the amounts to ensure it remains the max
            if controlling and controlling.claim_hash not in self.abandoned_claims:
                amounts[controlling.claim_hash] = self._get_pending_effective_amount(name, controlling.claim_hash)
            winning_claim_hash = max(amounts, key=lambda x: amounts[x])
            if not controlling or (winning_claim_hash != controlling.claim_hash and
                                   name in names_with_abandoned_or_updated_controlling_claims) or \
                    ((winning_claim_hash != controlling.claim_hash) and (amounts[winning_claim_hash] > amounts[controlling.claim_hash])):
                amounts_with_future_activations = {claim_hash: amount for claim_hash, amount in amounts.items()}
                amounts_with_future_activations.update(
                    {
                        claim_hash: self._get_pending_effective_amount(
                            name, claim_hash, self.height + 1 + self.coin.maxTakeoverDelay
                        ) for claim_hash in future_activations[name]
                    }
                )
                winning_including_future_activations = max(
                    amounts_with_future_activations, key=lambda x: amounts_with_future_activations[x]
                )
                future_winning_amount = amounts_with_future_activations[winning_including_future_activations]

                if winning_claim_hash != winning_including_future_activations and \
                        future_winning_amount > amounts[winning_claim_hash]:
                    # print(f"\ttakeover by {winning_claim_hash.hex()} triggered early activation and "
                    #       f"takeover by {winning_including_future_activations.hex()} at {height}")
                    # handle a pending activated claim jumping the takeover delay when another name takes over
                    if winning_including_future_activations not in self.claim_hash_to_txo:
                        claim = self.db.get_claim_txo(winning_including_future_activations)
                        tx_num = claim.tx_num
                        position = claim.position
                        amount = claim.amount
                        activation = self.db.get_activation(tx_num, position)
                    else:
                        tx_num, position = self.claim_hash_to_txo[winning_including_future_activations]
                        amount = self.txo_to_claim[(tx_num, position)].amount
                        activation = None
                        for (k, tx_amount) in activate_in_future[name][winning_including_future_activations]:
                            if (k.tx_num, k.position) == (tx_num, position):
                                activation = k.height
                                break
                        if activation is None:
                            # TODO: reproduce this in an integration test (block 604718)
                            _k = PendingActivationValue(winning_including_future_activations, name)
                            if _k in activated_at_height:
                                for pending_activation in activated_at_height[_k]:
                                    if (pending_activation.tx_num, pending_activation.position) == (tx_num, position):
                                        activation = pending_activation.height
                                        break
                        assert None not in (amount, activation)
                    # update the claim that's activating early
                    self.get_remove_activate_ops(
                        ACTIVATED_CLAIM_TXO_TYPE, winning_including_future_activations, tx_num,
                        position, activation, name, amount
                    )
                    self.get_activate_ops(
                        ACTIVATED_CLAIM_TXO_TYPE, winning_including_future_activations, tx_num,
                        position, height, name, amount
                    )

                    for (k, amount) in activate_in_future[name][winning_including_future_activations]:
                        txo = (k.tx_num, k.position)
                        if txo in self.possible_future_support_txos_by_claim_hash[winning_including_future_activations]:
                            self.get_remove_activate_ops(
                                ACTIVATED_SUPPORT_TXO_TYPE, winning_including_future_activations, k.tx_num,
                                k.position, k.height, name, amount
                            )
                            self.get_activate_ops(
                                ACTIVATED_SUPPORT_TXO_TYPE, winning_including_future_activations, k.tx_num,
                                k.position, height, name, amount
                            )
                    self.taken_over_names.add(name)
                    if controlling:
                        self.db.prefix_db.claim_takeover.stage_delete(
                            (name,), (controlling.claim_hash, controlling.height)
                        )
                    self.db.prefix_db.claim_takeover.stage_put((name,), (winning_including_future_activations, height))
                    self.touched_claim_hashes.add(winning_including_future_activations)
                    if controlling and controlling.claim_hash not in self.abandoned_claims:
                        self.touched_claim_hashes.add(controlling.claim_hash)
                elif not controlling or (winning_claim_hash != controlling.claim_hash and
                                       name in names_with_abandoned_or_updated_controlling_claims) or \
                        ((winning_claim_hash != controlling.claim_hash) and (amounts[winning_claim_hash] > amounts[controlling.claim_hash])):
                    # print(f"\ttakeover by {winning_claim_hash.hex()} at {height}")
                    if (name, winning_claim_hash) in need_reactivate_if_takes_over:
                        previous_pending_activate = need_reactivate_if_takes_over[(name, winning_claim_hash)]
                        amount = self.db.get_claim_txo_amount(
                            winning_claim_hash
                        )
                        if winning_claim_hash in self.claim_hash_to_txo:
                            tx_num, position = self.claim_hash_to_txo[winning_claim_hash]
                            amount = self.txo_to_claim[(tx_num, position)].amount
                        else:
                            tx_num, position = previous_pending_activate.tx_num, previous_pending_activate.position
                        if previous_pending_activate.height > height:
                            # the claim had a pending activation in the future, move it to now
                            if tx_num < self.tx_count:
                                self.get_remove_activate_ops(
                                    ACTIVATED_CLAIM_TXO_TYPE, winning_claim_hash, tx_num,
                                    position, previous_pending_activate.height, name, amount
                                )
                            self.get_activate_ops(
                                ACTIVATED_CLAIM_TXO_TYPE, winning_claim_hash, tx_num,
                                position, height, name, amount
                            )
                    self.taken_over_names.add(name)
                    if controlling:
                        self.db.prefix_db.claim_takeover.stage_delete(
                            (name,), (controlling.claim_hash, controlling.height)
                        )
                    self.db.prefix_db.claim_takeover.stage_put((name,), (winning_claim_hash, height))
                    if controlling and controlling.claim_hash not in self.abandoned_claims:
                        self.touched_claim_hashes.add(controlling.claim_hash)
                    self.touched_claim_hashes.add(winning_claim_hash)
                elif winning_claim_hash == controlling.claim_hash:
                    # print("\tstill winning")
                    pass
                else:
                    # print("\tno takeover")
                    pass

        # handle remaining takeovers from abandoned supports
        for (name, claim_hash), amounts in abandoned_support_check_need_takeover.items():
            if name in checked_names:
                continue
            checked_names.add(name)
            controlling = get_controlling(name)
            amounts = {
                claim_hash: self._get_pending_effective_amount(name, claim_hash)
                for claim_hash in self.db.get_claims_for_name(name) if claim_hash not in self.abandoned_claims
            }
            if controlling and controlling.claim_hash not in self.abandoned_claims:
                amounts[controlling.claim_hash] = self._get_pending_effective_amount(name, controlling.claim_hash)
            winning = max(amounts, key=lambda x: amounts[x])

            if (controlling and winning != controlling.claim_hash) or (not controlling and winning):
                self.taken_over_names.add(name)
                # print(f"\ttakeover from abandoned support {controlling.claim_hash.hex()} -> {winning.hex()}")
                if controlling:
                    self.db.prefix_db.claim_takeover.stage_delete(
                        (name,), (controlling.claim_hash, controlling.height)
                    )
                self.db.prefix_db.claim_takeover.stage_put((name,), (winning, height))
                if controlling:
                    self.touched_claim_hashes.add(controlling.claim_hash)
                self.touched_claim_hashes.add(winning)

    def _get_cumulative_update_ops(self, height: int):
        # update the last takeover height for names with takeovers
        for name in self.taken_over_names:
            self.touched_claim_hashes.update(
                {claim_hash for claim_hash in self.db.get_claims_for_name(name)
                 if claim_hash not in self.abandoned_claims}
            )

        # gather cumulative removed/touched sets to update the search index
        self.removed_claim_hashes.update(set(self.abandoned_claims.keys()))
        self.touched_claim_hashes.difference_update(self.removed_claim_hashes)
        self.touched_claim_hashes.update(
            set(
                map(lambda item: item[1], self.activated_claim_amount_by_name_and_hash.keys())
            ).union(
                set(self.claim_hash_to_txo.keys())
            ).union(
                self.removed_active_support_amount_by_claim.keys()
            ).union(
                self.signatures_changed
            ).union(
                set(self.removed_active_support_amount_by_claim.keys())
            ).union(
                set(self.activated_support_amount_by_claim.keys())
            ).union(
                set(self.pending_support_amount_change.keys())
            ).difference(
                self.removed_claim_hashes
            )
        )

        # update support amount totals
        for supported_claim, amount in self.pending_support_amount_change.items():
            existing = self.db.prefix_db.support_amount.get(supported_claim)
            total = amount
            if existing is not None:
                total += existing.amount
                self.db.prefix_db.support_amount.stage_delete((supported_claim,), existing)
            self.db.prefix_db.support_amount.stage_put((supported_claim,), (total,))

        # use the cumulative changes to update bid ordered resolve
        for removed in self.removed_claim_hashes:
            removed_claim = self.db.get_claim_txo(removed)
            if removed_claim:
                amt = self.db.get_url_effective_amount(
                    removed_claim.normalized_name, removed
                )
                if amt:
                    self.db.prefix_db.effective_amount.stage_delete(
                        (removed_claim.normalized_name, amt.effective_amount, amt.tx_num, amt.position), (removed,)
                    )
        for touched in self.touched_claim_hashes:
            prev_effective_amount = 0

            if touched in self.claim_hash_to_txo:
                pending = self.txo_to_claim[self.claim_hash_to_txo[touched]]
                name, tx_num, position = pending.normalized_name, pending.tx_num, pending.position
                claim_from_db = self.db.get_claim_txo(touched)
                if claim_from_db:
                    claim_amount_info = self.db.get_url_effective_amount(name, touched)
                    if claim_amount_info:
                        prev_effective_amount = claim_amount_info.effective_amount
                        self.db.prefix_db.effective_amount.stage_delete(
                            (name, claim_amount_info.effective_amount, claim_amount_info.tx_num,
                             claim_amount_info.position), (touched,)
                        )
            else:
                v = self.db.get_claim_txo(touched)
                if not v:
                    continue
                name, tx_num, position = v.normalized_name, v.tx_num, v.position
                amt = self.db.get_url_effective_amount(name, touched)
                if amt:
                    prev_effective_amount = amt.effective_amount
                    self.db.prefix_db.effective_amount.stage_delete(
                        (name, prev_effective_amount, amt.tx_num, amt.position), (touched,)
                    )

            new_effective_amount = self._get_pending_effective_amount(name, touched)
            self.db.prefix_db.effective_amount.stage_put(
                (name, new_effective_amount, tx_num, position), (touched,)
            )
            if touched in self.claim_hash_to_txo or touched in self.removed_claim_hashes \
                    or touched in self.pending_support_amount_change:
                # exclude sending notifications for claims/supports that activated but
                # weren't added/spent in this block
                self.db.prefix_db.trending_notification.stage_put(
                    (height, touched), (prev_effective_amount, new_effective_amount)
                )

        for channel_hash, count in self.pending_channel_counts.items():
            if count != 0:
                channel_count_val = self.db.prefix_db.channel_count.get(channel_hash)
                channel_count = 0 if not channel_count_val else channel_count_val.count
                if channel_count_val is not None:
                    self.db.prefix_db.channel_count.stage_delete((channel_hash,), (channel_count,))
                self.db.prefix_db.channel_count.stage_put((channel_hash,), (channel_count + count,))

        self.touched_claim_hashes.update(
            {k for k in self.pending_reposted if k not in self.removed_claim_hashes}
        )
        self.touched_claim_hashes.update(
            {k for k, v in self.pending_channel_counts.items() if v != 0 and k not in self.removed_claim_hashes}
        )
        self.touched_claims_to_send_es.update(self.touched_claim_hashes)
        self.touched_claims_to_send_es.difference_update(self.removed_claim_hashes)
        self.removed_claims_to_send_es.update(self.removed_claim_hashes)

    def advance_block(self, block):
        height = self.height + 1
        # print("advance ", height)
        # Use local vars for speed in the loops
        tx_count = self.tx_count
        spend_utxo = self.spend_utxo
        add_utxo = self.add_utxo
        spend_claim_or_support_txo = self._spend_claim_or_support_txo
        add_claim_or_support = self._add_claim_or_support
        txs: List[Tuple[Tx, bytes]] = block.transactions

        self.db.prefix_db.block_hash.stage_put(key_args=(height,), value_args=(self.coin.header_hash(block.header),))
        self.db.prefix_db.header.stage_put(key_args=(height,), value_args=(block.header,))
        self.db.prefix_db.block_txs.stage_put(key_args=(height,), value_args=([tx_hash for tx, tx_hash in txs],))

        for tx, tx_hash in txs:
            spent_claims = {}
            txos = Transaction(tx.raw).outputs

            # clean up mempool, delete txs that were already in mempool/staged to be added
            # leave txs in mempool that werent in the block
            mempool_tx = self.db.prefix_db.mempool_tx.get_pending(tx_hash)
            if mempool_tx:
                self.db.prefix_db.mempool_tx.stage_delete((tx_hash,), mempool_tx)

            self.db.prefix_db.tx.stage_put(key_args=(tx_hash,), value_args=(tx.raw,))
            self.db.prefix_db.tx_num.stage_put(key_args=(tx_hash,), value_args=(tx_count,))
            self.db.prefix_db.tx_hash.stage_put(key_args=(tx_count,), value_args=(tx_hash,))

            # Spend the inputs
            for txin in tx.inputs:
                if txin.is_generation():
                    continue
                # spend utxo for address histories
                hashX = spend_utxo(txin.prev_hash, txin.prev_idx)
                if hashX:
                    if tx_count not in self.hashXs_by_tx[hashX]:
                        self.hashXs_by_tx[hashX].append(tx_count)
                # spend claim/support txo
                spend_claim_or_support_txo(height, txin, spent_claims)

            # Add the new UTXOs
            for nout, txout in enumerate(tx.outputs):
                # Get the hashX.  Ignore unspendable outputs
                hashX = add_utxo(tx_hash, tx_count, nout, txout)
                if hashX:
                    # self._set_hashX_cache(hashX)
                    if tx_count not in self.hashXs_by_tx[hashX]:
                        self.hashXs_by_tx[hashX].append(tx_count)
                # add claim/support txo
                add_claim_or_support(
                    height, tx_hash, tx_count, nout, txos[nout], spent_claims
                )

            # Handle abandoned claims
            abandoned_channels = {}
            # abandon the channels last to handle abandoned signed claims in the same tx,
            # see test_abandon_channel_and_claims_in_same_tx
            for abandoned_claim_hash, (tx_num, nout, normalized_name) in spent_claims.items():
                if normalized_name.startswith('@'):
                    abandoned_channels[abandoned_claim_hash] = (tx_num, nout, normalized_name)
                else:
                    # print(f"\tabandon {normalized_name} {abandoned_claim_hash.hex()} {tx_num} {nout}")
                    self._abandon_claim(abandoned_claim_hash, tx_num, nout, normalized_name)

            for abandoned_claim_hash, (tx_num, nout, normalized_name) in abandoned_channels.items():
                # print(f"\tabandon {normalized_name} {abandoned_claim_hash.hex()} {tx_num} {nout}")
                self._abandon_claim(abandoned_claim_hash, tx_num, nout, normalized_name)
            self.pending_transactions[tx_count] = tx_hash
            self.pending_transaction_num_mapping[tx_hash] = tx_count
            if self.env.cache_all_tx_hashes:
                self.db.total_transactions.append(tx_hash)
                self.db.tx_num_mapping[tx_hash] = tx_count
            tx_count += 1

        # handle expired claims
        self._expire_claims(height)

        # activate claims and process takeovers
        self._get_takeover_ops(height)

        # update effective amount and update sets of touched and deleted claims
        self._get_cumulative_update_ops(height)

        self.db.prefix_db.touched_hashX.stage_put((height,), (list(sorted(self.touched_hashXs)),))

        self.db.prefix_db.tx_count.stage_put(key_args=(height,), value_args=(tx_count,))

        for hashX, new_history in self.hashXs_by_tx.items():
            if not new_history:
                continue
            self.db.prefix_db.hashX_history.stage_put(key_args=(hashX, height), value_args=(new_history,))

        self.tx_count = tx_count
        self.db.tx_counts.append(self.tx_count)

        cached_max_reorg_depth = self.daemon.cached_height() - self.env.reorg_limit

        # if height >= cached_max_reorg_depth:
        self.db.prefix_db.touched_or_deleted.stage_put(
            key_args=(height,), value_args=(self.touched_claim_hashes, self.removed_claim_hashes)
        )

        self.height = height
        self.db.headers.append(block.header)
        self.tip = self.coin.header_hash(block.header)

        min_height = self.db.min_undo_height(self.db.db_height)
        if min_height > 0:  # delete undos for blocks deep enough they can't be reorged
            undo_to_delete = list(self.db.prefix_db.undo.iterate(start=(0,), stop=(min_height,)))
            for (k, v) in undo_to_delete:
                self.db.prefix_db.undo.stage_delete((k,), (v,))
            touched_or_deleted_to_delete = list(self.db.prefix_db.touched_or_deleted.iterate(
                start=(0,), stop=(min_height,))
            )
            for (k, v) in touched_or_deleted_to_delete:
                self.db.prefix_db.touched_or_deleted.stage_delete(k, v)

        self.db.fs_height = self.height
        self.db.fs_tx_count = self.tx_count
        self.db.hist_flush_count += 1
        self.db.hist_unflushed_count = 0
        self.db.utxo_flush_count = self.db.hist_flush_count
        self.db.db_height = self.height
        self.db.db_tx_count = self.tx_count
        self.db.db_tip = self.tip
        self.db.last_flush_tx_count = self.db.fs_tx_count
        now = time.time()
        self.db.wall_time += now - self.db.last_flush
        self.db.last_flush = now
        self.db.write_db_state()

    def clear_after_advance_or_reorg(self):
        self.txo_to_claim.clear()
        self.claim_hash_to_txo.clear()
        self.support_txos_by_claim.clear()
        self.support_txo_to_claim.clear()
        self.removed_support_txos_by_name_by_claim.clear()
        self.abandoned_claims.clear()
        self.removed_active_support_amount_by_claim.clear()
        self.activated_support_amount_by_claim.clear()
        self.activated_claim_amount_by_name_and_hash.clear()
        self.activation_by_claim_by_name.clear()
        self.possible_future_claim_amount_by_name_and_hash.clear()
        self.possible_future_support_amounts_by_claim_hash.clear()
        self.possible_future_support_txos_by_claim_hash.clear()
        self.pending_channels.clear()
        self.amount_cache.clear()
        self.signatures_changed.clear()
        self.expired_claim_hashes.clear()
        self.doesnt_have_valid_signature.clear()
        self.claim_channels.clear()
        self.utxo_cache.clear()
        self.hashXs_by_tx.clear()
        self.history_cache.clear()
        self.removed_claim_hashes.clear()
        self.touched_claim_hashes.clear()
        self.pending_reposted.clear()
        self.pending_channel_counts.clear()
        self.updated_claims.clear()
        self.taken_over_names.clear()
        self.pending_transaction_num_mapping.clear()
        self.pending_transactions.clear()
        self.pending_support_amount_change.clear()
        self.resolve_cache.clear()
        self.resolve_outputs_cache.clear()
        self.touched_hashXs.clear()

    async def backup_block(self):
        assert len(self.db.prefix_db._op_stack) == 0
        touched_and_deleted = self.db.prefix_db.touched_or_deleted.get(self.height)
        self.touched_claims_to_send_es.update(touched_and_deleted.touched_claims)
        self.removed_claims_to_send_es.difference_update(touched_and_deleted.touched_claims)
        self.removed_claims_to_send_es.update(touched_and_deleted.deleted_claims)

        # self.db.assert_flushed(self.flush_data())
        self.logger.info("backup block %i", self.height)
        # Check and update self.tip

        self.db.tx_counts.pop()
        reverted_block_hash = self.coin.header_hash(self.db.headers.pop())
        self.tip = self.coin.header_hash(self.db.headers[-1])
        if self.env.cache_all_tx_hashes:
            while len(self.db.total_transactions) > self.db.tx_counts[-1]:
                self.db.tx_num_mapping.pop(self.db.total_transactions.pop())
                self.tx_count -= 1
        else:
            self.tx_count = self.db.tx_counts[-1]
        self.height -= 1

        # self.touched can include other addresses which is
        # harmless, but remove None.
        self.touched_hashXs.discard(None)

        assert self.height < self.db.db_height
        assert not self.db.hist_unflushed

        start_time = time.time()
        tx_delta = self.tx_count - self.db.last_flush_tx_count
        ###
        self.db.fs_tx_count = self.tx_count
        # Truncate header_mc: header count is 1 more than the height.
        self.db.header_mc.truncate(self.height + 1)
        ###
        # Not certain this is needed, but it doesn't hurt
        self.db.hist_flush_count += 1

        while self.db.fs_height > self.height:
            self.db.fs_height -= 1
        self.db.utxo_flush_count = self.db.hist_flush_count
        self.db.db_height = self.height
        self.db.db_tx_count = self.tx_count
        self.db.db_tip = self.tip
        # Flush state last as it reads the wall time.
        now = time.time()
        self.db.wall_time += now - self.db.last_flush
        self.db.last_flush = now
        self.db.last_flush_tx_count = self.db.fs_tx_count

        def rollback():
            self.db.prefix_db.rollback(self.height + 1, reverted_block_hash)
            self.db.es_sync_height = self.height
            self.db.write_db_state()
            self.db.prefix_db.unsafe_commit()

        await self.run_in_thread_with_lock(rollback)
        self.clear_after_advance_or_reorg()
        self.db.assert_db_state()

        elapsed = self.db.last_flush - start_time
        self.logger.warning(f'backup flush #{self.db.hist_flush_count:,d} took {elapsed:.1f}s. '
                            f'Height {self.height:,d} txs: {self.tx_count:,d} ({tx_delta:+,d})')

    def add_utxo(self, tx_hash: bytes, tx_num: int, nout: int, txout: 'TxOutput') -> Optional[bytes]:
        hashX = self.coin.hashX_from_script(txout.pk_script)
        if hashX:
            self.touched_hashXs.add(hashX)
            self.utxo_cache[(tx_hash, nout)] = (hashX, txout.value)
            self.db.prefix_db.utxo.stage_put((hashX, tx_num, nout), (txout.value,))
            self.db.prefix_db.hashX_utxo.stage_put((tx_hash[:4], tx_num, nout), (hashX,))
            return hashX

    def get_pending_tx_num(self, tx_hash: bytes) -> int:
        if tx_hash in self.pending_transaction_num_mapping:
            return self.pending_transaction_num_mapping[tx_hash]
        else:
            return self.db.get_tx_num(tx_hash)

    def spend_utxo(self, tx_hash: bytes, nout: int):
        hashX, amount = self.utxo_cache.pop((tx_hash, nout), (None, None))
        txin_num = self.get_pending_tx_num(tx_hash)
        if not hashX:
            hashX_value = self.db.prefix_db.hashX_utxo.get(tx_hash[:4], txin_num, nout)
            if not hashX_value:
                return
            hashX = hashX_value.hashX
            utxo_value = self.db.prefix_db.utxo.get(hashX, txin_num, nout)
            if not utxo_value:
                self.logger.warning(
                    "%s:%s is not found in UTXO db for %s", hash_to_hex_str(tx_hash), nout, hash_to_hex_str(hashX)
                )
                raise ChainError(
                    f"{hash_to_hex_str(tx_hash)}:{nout} is not found in UTXO db for {hash_to_hex_str(hashX)}"
                )
            self.touched_hashXs.add(hashX)
            self.db.prefix_db.hashX_utxo.stage_delete((tx_hash[:4], txin_num, nout), hashX_value)
            self.db.prefix_db.utxo.stage_delete((hashX, txin_num, nout), utxo_value)
            return hashX
        elif amount is not None:
            self.db.prefix_db.hashX_utxo.stage_delete((tx_hash[:4], txin_num, nout), (hashX,))
            self.db.prefix_db.utxo.stage_delete((hashX, txin_num, nout), (amount,))
            self.touched_hashXs.add(hashX)
            return hashX

    async def process_blocks_and_mempool_forever(self):
        """Loop forever processing blocks as they arrive."""
        while True:
            if self.height == self.daemon.cached_height():
                if not self._caught_up_event.is_set():
                    await self._first_caught_up()
                    self._caught_up_event.set()
            try:
                await asyncio.wait_for(self.blocks_event.wait(), 0.25)
            except asyncio.TimeoutError:
                pass
            self.blocks_event.clear()
            blocks = self.prefetcher.get_prefetched_blocks()
            if not blocks:
                try:
                    await self.check_mempool()
                    self.db.prefix_db.unsafe_commit()
                except Exception:
                    self.logger.exception("error while updating mempool txs")
                    raise
            else:
                try:
                    await self.check_and_advance_blocks(blocks)
                except Exception:
                    self.logger.exception("error while processing txs")
                    raise

    async def _es_caught_up(self):
        self.db.es_sync_height = self.height

        def flush():
            assert len(self.db.prefix_db._op_stack) == 0
            self.db.write_db_state()
            self.db.prefix_db.unsafe_commit()
            self.db.assert_db_state()

        await self.run_in_thread_with_lock(flush)

    async def _first_caught_up(self):
        self.logger.info(f'caught up to height {self.height}')
        # Flush everything but with first_sync->False state.
        first_sync = self.db.first_sync
        self.db.first_sync = False

        def flush():
            assert len(self.db.prefix_db._op_stack) == 0
            self.db.write_db_state()
            self.db.prefix_db.unsafe_commit()
            self.db.assert_db_state()

        await self.run_in_thread_with_lock(flush)

        if first_sync:
            self.logger.info(f'{lbry.__version__} synced to '
                             f'height {self.height:,d}, halting here.')
            self.shutdown_event.set()

    async def open(self):
        self.db.open_db()
        self.height = self.db.db_height
        self.tip = self.db.db_tip
        self.tx_count = self.db.db_tx_count
        await self.db.initialize_caches()

    async def fetch_and_process_blocks(self, caught_up_event):
        """Fetch, process and index blocks from the daemon.

        Sets caught_up_event when first caught up.  Flushes to disk
        and shuts down cleanly if cancelled.

        This is mainly because if, during initial sync ElectrumX is
        asked to shut down when a large number of blocks have been
        processed but not written to disk, it should write those to
        disk before exiting, as otherwise a significant amount of work
        could be lost.
        """

        self._caught_up_event = caught_up_event
        try:
            await asyncio.wait([
                self.prefetcher.main_loop(self.height),
                self.process_blocks_and_mempool_forever()
            ])
        except asyncio.CancelledError:
            raise
        except:
            self.logger.exception("Block processing failed!")
            raise
        finally:
            # Shut down block processing
            self.logger.info('closing the DB for a clean shutdown...')
            self._sync_reader_executor.shutdown(wait=True)
            self._chain_executor.shutdown(wait=True)
            self.db.close()

    async def start(self):
        env = self.env
        min_str, max_str = env.coin.SESSIONCLS.protocol_min_max_strings()
        self.logger.info(f'software version: {lbry.__version__}')
        self.logger.info(f'supported protocol versions: {min_str}-{max_str}')
        self.logger.info(f'event loop policy: {env.loop_policy}')
        self.logger.info(f'reorg limit is {env.reorg_limit:,d} blocks')

        await self.daemon.height()

        def _start_cancellable(run, *args):
            _flag = asyncio.Event()
            self.cancellable_tasks.append(asyncio.ensure_future(run(*args, _flag)))
            return _flag.wait()

        await _start_cancellable(self.fetch_and_process_blocks)

    async def stop(self):
        for task in reversed(self.cancellable_tasks):
            task.cancel()
        await asyncio.wait(self.cancellable_tasks)
        self.shutdown_event.set()
        await self.daemon.close()

    def run(self):
        loop = asyncio.get_event_loop()

        def __exit():
            raise SystemExit()
        try:
            loop.add_signal_handler(signal.SIGINT, __exit)
            loop.add_signal_handler(signal.SIGTERM, __exit)
            loop.run_until_complete(self.start())
            loop.run_until_complete(self.shutdown_event.wait())
        except (SystemExit, KeyboardInterrupt):
            pass
        finally:
            loop.run_until_complete(self.stop())