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// Copyright (c) 2017-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <chainparams.h>
#include <common/args.h>
#include <index/base.h>
#include <interfaces/chain.h>
#include <kernel/chain.h>
#include <logging.h>
#include <node/abort.h>
#include <node/blockstorage.h>
#include <node/context.h>
#include <node/database_args.h>
#include <node/interface_ui.h>
#include <tinyformat.h>
#include <util/thread.h>
#include <util/translation.h>
#include <validation.h> // For g_chainman
#include <warnings.h>
#include <string>
#include <utility>
constexpr uint8_t DB_BEST_BLOCK{'B'};
constexpr auto SYNC_LOG_INTERVAL{30s};
constexpr auto SYNC_LOCATOR_WRITE_INTERVAL{30s};
template <typename... Args>
void BaseIndex::FatalErrorf(const char* fmt, const Args&... args)
{
auto message = tfm::format(fmt, args...);
node::AbortNode(m_chain->context()->shutdown, m_chain->context()->exit_status, message);
}
CBlockLocator GetLocator(interfaces::Chain& chain, const uint256& block_hash)
{
CBlockLocator locator;
bool found = chain.findBlock(block_hash, interfaces::FoundBlock().locator(locator));
assert(found);
assert(!locator.IsNull());
return locator;
}
BaseIndex::DB::DB(const fs::path& path, size_t n_cache_size, bool f_memory, bool f_wipe, bool f_obfuscate) :
CDBWrapper{DBParams{
.path = path,
.cache_bytes = n_cache_size,
.memory_only = f_memory,
.wipe_data = f_wipe,
.obfuscate = f_obfuscate,
.options = [] { DBOptions options; node::ReadDatabaseArgs(gArgs, options); return options; }()}}
{}
bool BaseIndex::DB::ReadBestBlock(CBlockLocator& locator) const
{
bool success = Read(DB_BEST_BLOCK, locator);
if (!success) {
locator.SetNull();
}
return success;
}
void BaseIndex::DB::WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator)
{
batch.Write(DB_BEST_BLOCK, locator);
}
BaseIndex::BaseIndex(std::unique_ptr<interfaces::Chain> chain, std::string name)
: m_chain{std::move(chain)}, m_name{std::move(name)} {}
BaseIndex::~BaseIndex()
{
Interrupt();
Stop();
}
bool BaseIndex::Init()
{
AssertLockNotHeld(cs_main);
// May need reset if index is being restarted.
m_interrupt.reset();
// m_chainstate member gives indexing code access to node internals. It is
// removed in followup https://github.com/bitcoin/bitcoin/pull/24230
m_chainstate = WITH_LOCK(::cs_main,
return &m_chain->context()->chainman->GetChainstateForIndexing());
// Register to validation interface before setting the 'm_synced' flag, so that
// callbacks are not missed once m_synced is true.
m_chain->context()->validation_signals->RegisterValidationInterface(this);
CBlockLocator locator;
if (!GetDB().ReadBestBlock(locator)) {
locator.SetNull();
}
LOCK(cs_main);
CChain& index_chain = m_chainstate->m_chain;
if (locator.IsNull()) {
SetBestBlockIndex(nullptr);
} else {
// Setting the best block to the locator's top block. If it is not part of the
// best chain, we will rewind to the fork point during index sync
const CBlockIndex* locator_index{m_chainstate->m_blockman.LookupBlockIndex(locator.vHave.at(0))};
if (!locator_index) {
return InitError(strprintf(Untranslated("%s: best block of the index not found. Please rebuild the index."), GetName()));
}
SetBestBlockIndex(locator_index);
}
// Child init
const CBlockIndex* start_block = m_best_block_index.load();
if (!CustomInit(start_block ? std::make_optional(interfaces::BlockKey{start_block->GetBlockHash(), start_block->nHeight}) : std::nullopt)) {
return false;
}
// Note: this will latch to true immediately if the user starts up with an empty
// datadir and an index enabled. If this is the case, indexation will happen solely
// via `BlockConnected` signals until, possibly, the next restart.
m_synced = start_block == index_chain.Tip();
m_init = true;
return true;
}
static const CBlockIndex* NextSyncBlock(const CBlockIndex* pindex_prev, CChain& chain) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
AssertLockHeld(cs_main);
if (!pindex_prev) {
return chain.Genesis();
}
const CBlockIndex* pindex = chain.Next(pindex_prev);
if (pindex) {
return pindex;
}
return chain.Next(chain.FindFork(pindex_prev));
}
void BaseIndex::ThreadSync()
{
const CBlockIndex* pindex = m_best_block_index.load();
if (!m_synced) {
std::chrono::steady_clock::time_point last_log_time{0s};
std::chrono::steady_clock::time_point last_locator_write_time{0s};
while (true) {
if (m_interrupt) {
LogPrintf("%s: m_interrupt set; exiting ThreadSync\n", GetName());
SetBestBlockIndex(pindex);
// No need to handle errors in Commit. If it fails, the error will be already be
// logged. The best way to recover is to continue, as index cannot be corrupted by
// a missed commit to disk for an advanced index state.
Commit();
return;
}
{
LOCK(cs_main);
const CBlockIndex* pindex_next = NextSyncBlock(pindex, m_chainstate->m_chain);
if (!pindex_next) {
SetBestBlockIndex(pindex);
m_synced = true;
// No need to handle errors in Commit. See rationale above.
Commit();
break;
}
if (pindex_next->pprev != pindex && !Rewind(pindex, pindex_next->pprev)) {
FatalErrorf("%s: Failed to rewind index %s to a previous chain tip",
__func__, GetName());
return;
}
pindex = pindex_next;
}
auto current_time{std::chrono::steady_clock::now()};
if (last_log_time + SYNC_LOG_INTERVAL < current_time) {
LogPrintf("Syncing %s with block chain from height %d\n",
GetName(), pindex->nHeight);
last_log_time = current_time;
}
if (last_locator_write_time + SYNC_LOCATOR_WRITE_INTERVAL < current_time) {
SetBestBlockIndex(pindex->pprev);
last_locator_write_time = current_time;
// No need to handle errors in Commit. See rationale above.
Commit();
}
CBlock block;
interfaces::BlockInfo block_info = kernel::MakeBlockInfo(pindex);
if (!m_chainstate->m_blockman.ReadBlockFromDisk(block, *pindex)) {
FatalErrorf("%s: Failed to read block %s from disk",
__func__, pindex->GetBlockHash().ToString());
return;
} else {
block_info.data = █
}
if (!CustomAppend(block_info)) {
FatalErrorf("%s: Failed to write block %s to index database",
__func__, pindex->GetBlockHash().ToString());
return;
}
}
}
if (pindex) {
LogPrintf("%s is enabled at height %d\n", GetName(), pindex->nHeight);
} else {
LogPrintf("%s is enabled\n", GetName());
}
}
bool BaseIndex::Commit()
{
// Don't commit anything if we haven't indexed any block yet
// (this could happen if init is interrupted).
bool ok = m_best_block_index != nullptr;
if (ok) {
CDBBatch batch(GetDB());
ok = CustomCommit(batch);
if (ok) {
GetDB().WriteBestBlock(batch, GetLocator(*m_chain, m_best_block_index.load()->GetBlockHash()));
ok = GetDB().WriteBatch(batch);
}
}
if (!ok) {
error("%s: Failed to commit latest %s state", __func__, GetName());
return false;
}
return true;
}
bool BaseIndex::Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip)
{
assert(current_tip == m_best_block_index);
assert(current_tip->GetAncestor(new_tip->nHeight) == new_tip);
if (!CustomRewind({current_tip->GetBlockHash(), current_tip->nHeight}, {new_tip->GetBlockHash(), new_tip->nHeight})) {
return false;
}
// In the case of a reorg, ensure persisted block locator is not stale.
// Pruning has a minimum of 288 blocks-to-keep and getting the index
// out of sync may be possible but a users fault.
// In case we reorg beyond the pruned depth, ReadBlockFromDisk would
// throw and lead to a graceful shutdown
SetBestBlockIndex(new_tip);
if (!Commit()) {
// If commit fails, revert the best block index to avoid corruption.
SetBestBlockIndex(current_tip);
return false;
}
return true;
}
void BaseIndex::BlockConnected(ChainstateRole role, const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex)
{
// Ignore events from the assumed-valid chain; we will process its blocks
// (sequentially) after it is fully verified by the background chainstate. This
// is to avoid any out-of-order indexing.
//
// TODO at some point we could parameterize whether a particular index can be
// built out of order, but for now just do the conservative simple thing.
if (role == ChainstateRole::ASSUMEDVALID) {
return;
}
// Ignore BlockConnected signals until we have fully indexed the chain.
if (!m_synced) {
return;
}
const CBlockIndex* best_block_index = m_best_block_index.load();
if (!best_block_index) {
if (pindex->nHeight != 0) {
FatalErrorf("%s: First block connected is not the genesis block (height=%d)",
__func__, pindex->nHeight);
return;
}
} else {
// Ensure block connects to an ancestor of the current best block. This should be the case
// most of the time, but may not be immediately after the sync thread catches up and sets
// m_synced. Consider the case where there is a reorg and the blocks on the stale branch are
// in the ValidationInterface queue backlog even after the sync thread has caught up to the
// new chain tip. In this unlikely event, log a warning and let the queue clear.
if (best_block_index->GetAncestor(pindex->nHeight - 1) != pindex->pprev) {
LogPrintf("%s: WARNING: Block %s does not connect to an ancestor of "
"known best chain (tip=%s); not updating index\n",
__func__, pindex->GetBlockHash().ToString(),
best_block_index->GetBlockHash().ToString());
return;
}
if (best_block_index != pindex->pprev && !Rewind(best_block_index, pindex->pprev)) {
FatalErrorf("%s: Failed to rewind index %s to a previous chain tip",
__func__, GetName());
return;
}
}
interfaces::BlockInfo block_info = kernel::MakeBlockInfo(pindex, block.get());
if (CustomAppend(block_info)) {
// Setting the best block index is intentionally the last step of this
// function, so BlockUntilSyncedToCurrentChain callers waiting for the
// best block index to be updated can rely on the block being fully
// processed, and the index object being safe to delete.
SetBestBlockIndex(pindex);
} else {
FatalErrorf("%s: Failed to write block %s to index",
__func__, pindex->GetBlockHash().ToString());
return;
}
}
void BaseIndex::ChainStateFlushed(ChainstateRole role, const CBlockLocator& locator)
{
// Ignore events from the assumed-valid chain; we will process its blocks
// (sequentially) after it is fully verified by the background chainstate.
if (role == ChainstateRole::ASSUMEDVALID) {
return;
}
if (!m_synced) {
return;
}
const uint256& locator_tip_hash = locator.vHave.front();
const CBlockIndex* locator_tip_index;
{
LOCK(cs_main);
locator_tip_index = m_chainstate->m_blockman.LookupBlockIndex(locator_tip_hash);
}
if (!locator_tip_index) {
FatalErrorf("%s: First block (hash=%s) in locator was not found",
__func__, locator_tip_hash.ToString());
return;
}
// This checks that ChainStateFlushed callbacks are received after BlockConnected. The check may fail
// immediately after the sync thread catches up and sets m_synced. Consider the case where
// there is a reorg and the blocks on the stale branch are in the ValidationInterface queue
// backlog even after the sync thread has caught up to the new chain tip. In this unlikely
// event, log a warning and let the queue clear.
const CBlockIndex* best_block_index = m_best_block_index.load();
if (best_block_index->GetAncestor(locator_tip_index->nHeight) != locator_tip_index) {
LogPrintf("%s: WARNING: Locator contains block (hash=%s) not on known best "
"chain (tip=%s); not writing index locator\n",
__func__, locator_tip_hash.ToString(),
best_block_index->GetBlockHash().ToString());
return;
}
// No need to handle errors in Commit. If it fails, the error will be already be logged. The
// best way to recover is to continue, as index cannot be corrupted by a missed commit to disk
// for an advanced index state.
Commit();
}
bool BaseIndex::BlockUntilSyncedToCurrentChain() const
{
AssertLockNotHeld(cs_main);
if (!m_synced) {
return false;
}
{
// Skip the queue-draining stuff if we know we're caught up with
// m_chain.Tip().
LOCK(cs_main);
const CBlockIndex* chain_tip = m_chainstate->m_chain.Tip();
const CBlockIndex* best_block_index = m_best_block_index.load();
if (best_block_index->GetAncestor(chain_tip->nHeight) == chain_tip) {
return true;
}
}
LogPrintf("%s: %s is catching up on block notifications\n", __func__, GetName());
m_chain->context()->validation_signals->SyncWithValidationInterfaceQueue();
return true;
}
void BaseIndex::Interrupt()
{
m_interrupt();
}
bool BaseIndex::StartBackgroundSync()
{
if (!m_init) throw std::logic_error("Error: Cannot start a non-initialized index");
m_thread_sync = std::thread(&util::TraceThread, GetName(), [this] { ThreadSync(); });
return true;
}
void BaseIndex::Stop()
{
if (m_chain->context()->validation_signals) {
m_chain->context()->validation_signals->UnregisterValidationInterface(this);
}
if (m_thread_sync.joinable()) {
m_thread_sync.join();
}
}
IndexSummary BaseIndex::GetSummary() const
{
IndexSummary summary{};
summary.name = GetName();
summary.synced = m_synced;
if (const auto& pindex = m_best_block_index.load()) {
summary.best_block_height = pindex->nHeight;
summary.best_block_hash = pindex->GetBlockHash();
} else {
summary.best_block_height = 0;
summary.best_block_hash = m_chain->getBlockHash(0);
}
return summary;
}
void BaseIndex::SetBestBlockIndex(const CBlockIndex* block)
{
assert(!m_chainstate->m_blockman.IsPruneMode() || AllowPrune());
if (AllowPrune() && block) {
node::PruneLockInfo prune_lock;
prune_lock.height_first = block->nHeight;
WITH_LOCK(::cs_main, m_chainstate->m_blockman.UpdatePruneLock(GetName(), prune_lock));
}
// Intentionally set m_best_block_index as the last step in this function,
// after updating prune locks above, and after making any other references
// to *this, so the BlockUntilSyncedToCurrentChain function (which checks
// m_best_block_index as an optimization) can be used to wait for the last
// BlockConnected notification and safely assume that prune locks are
// updated and that the index object is safe to delete.
m_best_block_index = block;
}
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