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bitcoin/src/index/blockfilterindex.cpp

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// Copyright (c) 2018-2022 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 <map>
#include <clientversion.h>
#include <common/args.h>
#include <dbwrapper.h>
#include <hash.h>
#include <index/blockfilterindex.h>
#include <logging.h>
#include <node/blockstorage.h>
#include <undo.h>
#include <util/fs_helpers.h>
#include <validation.h>
/* The index database stores three items for each block: the disk location of the encoded filter,
* its dSHA256 hash, and the header. Those belonging to blocks on the active chain are indexed by
* height, and those belonging to blocks that have been reorganized out of the active chain are
* indexed by block hash. This ensures that filter data for any block that becomes part of the
* active chain can always be retrieved, alleviating timing concerns.
*
* The filters themselves are stored in flat files and referenced by the LevelDB entries. This
* minimizes the amount of data written to LevelDB and keeps the database values constant size. The
* disk location of the next block filter to be written (represented as a FlatFilePos) is stored
* under the DB_FILTER_POS key.
*
* Keys for the height index have the type [DB_BLOCK_HEIGHT, uint32 (BE)]. The height is represented
* as big-endian so that sequential reads of filters by height are fast.
* Keys for the hash index have the type [DB_BLOCK_HASH, uint256].
*/
constexpr uint8_t DB_BLOCK_HASH{'s'};
constexpr uint8_t DB_BLOCK_HEIGHT{'t'};
constexpr uint8_t DB_FILTER_POS{'P'};
constexpr unsigned int MAX_FLTR_FILE_SIZE = 0x1000000; // 16 MiB
/** The pre-allocation chunk size for fltr?????.dat files */
constexpr unsigned int FLTR_FILE_CHUNK_SIZE = 0x100000; // 1 MiB
/** Maximum size of the cfheaders cache
* We have a limit to prevent a bug in filling this cache
* potentially turning into an OOM. At 2000 entries, this cache
* is big enough for a 2,000,000 length block chain, which
* we should be enough until ~2047. */
constexpr size_t CF_HEADERS_CACHE_MAX_SZ{2000};
namespace {
struct DBVal {
uint256 hash;
uint256 header;
FlatFilePos pos;
SERIALIZE_METHODS(DBVal, obj) { READWRITE(obj.hash, obj.header, obj.pos); }
};
struct DBHeightKey {
int height;
explicit DBHeightKey(int height_in) : height(height_in) {}
template<typename Stream>
void Serialize(Stream& s) const
{
ser_writedata8(s, DB_BLOCK_HEIGHT);
ser_writedata32be(s, height);
}
template<typename Stream>
void Unserialize(Stream& s)
{
const uint8_t prefix{ser_readdata8(s)};
if (prefix != DB_BLOCK_HEIGHT) {
throw std::ios_base::failure("Invalid format for block filter index DB height key");
}
height = ser_readdata32be(s);
}
};
struct DBHashKey {
uint256 hash;
explicit DBHashKey(const uint256& hash_in) : hash(hash_in) {}
SERIALIZE_METHODS(DBHashKey, obj) {
uint8_t prefix{DB_BLOCK_HASH};
READWRITE(prefix);
if (prefix != DB_BLOCK_HASH) {
throw std::ios_base::failure("Invalid format for block filter index DB hash key");
}
READWRITE(obj.hash);
}
};
}; // namespace
static std::map<BlockFilterType, BlockFilterIndex> g_filter_indexes;
BlockFilterIndex::BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
size_t n_cache_size, bool f_memory, bool f_wipe)
: BaseIndex(std::move(chain), BlockFilterTypeName(filter_type) + " block filter index")
, m_filter_type(filter_type)
{
const std::string& filter_name = BlockFilterTypeName(filter_type);
if (filter_name.empty()) throw std::invalid_argument("unknown filter_type");
fs::path path = gArgs.GetDataDirNet() / "indexes" / "blockfilter" / fs::u8path(filter_name);
fs::create_directories(path);
m_db = std::make_unique<BaseIndex::DB>(path / "db", n_cache_size, f_memory, f_wipe);
m_filter_fileseq = std::make_unique<FlatFileSeq>(std::move(path), "fltr", FLTR_FILE_CHUNK_SIZE);
}
bool BlockFilterIndex::CustomInit(const std::optional<interfaces::BlockKey>& block)
{
if (!m_db->Read(DB_FILTER_POS, m_next_filter_pos)) {
// Check that the cause of the read failure is that the key does not exist. Any other errors
// indicate database corruption or a disk failure, and starting the index would cause
// further corruption.
if (m_db->Exists(DB_FILTER_POS)) {
LogError("%s: Cannot read current %s state; index may be corrupted\n",
__func__, GetName());
return false;
}
// If the DB_FILTER_POS is not set, then initialize to the first location.
m_next_filter_pos.nFile = 0;
m_next_filter_pos.nPos = 0;
}
if (block) {
auto op_last_header = ReadFilterHeader(block->height, block->hash);
if (!op_last_header) {
LogError("Cannot read last block filter header; index may be corrupted\n");
return false;
}
m_last_header = *op_last_header;
}
return true;
}
bool BlockFilterIndex::CustomCommit(CDBBatch& batch)
{
const FlatFilePos& pos = m_next_filter_pos;
// Flush current filter file to disk.
AutoFile file{m_filter_fileseq->Open(pos)};
if (file.IsNull()) {
LogError("%s: Failed to open filter file %d\n", __func__, pos.nFile);
return false;
}
if (!FileCommit(file.Get())) {
LogError("%s: Failed to commit filter file %d\n", __func__, pos.nFile);
return false;
}
batch.Write(DB_FILTER_POS, pos);
return true;
}
bool BlockFilterIndex::ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const
{
AutoFile filein{m_filter_fileseq->Open(pos, true)};
if (filein.IsNull()) {
return false;
}
// Check that the hash of the encoded_filter matches the one stored in the db.
uint256 block_hash;
std::vector<uint8_t> encoded_filter;
try {
filein >> block_hash >> encoded_filter;
if (Hash(encoded_filter) != hash) {
LogError("Checksum mismatch in filter decode.\n");
return false;
}
filter = BlockFilter(GetFilterType(), block_hash, std::move(encoded_filter), /*skip_decode_check=*/true);
}
catch (const std::exception& e) {
LogError("%s: Failed to deserialize block filter from disk: %s\n", __func__, e.what());
return false;
}
return true;
}
size_t BlockFilterIndex::WriteFilterToDisk(FlatFilePos& pos, const BlockFilter& filter)
{
assert(filter.GetFilterType() == GetFilterType());
size_t data_size =
GetSerializeSize(filter.GetBlockHash()) +
GetSerializeSize(filter.GetEncodedFilter());
// If writing the filter would overflow the file, flush and move to the next one.
if (pos.nPos + data_size > MAX_FLTR_FILE_SIZE) {
AutoFile last_file{m_filter_fileseq->Open(pos)};
if (last_file.IsNull()) {
LogPrintf("%s: Failed to open filter file %d\n", __func__, pos.nFile);
return 0;
}
if (!TruncateFile(last_file.Get(), pos.nPos)) {
LogPrintf("%s: Failed to truncate filter file %d\n", __func__, pos.nFile);
return 0;
}
if (!FileCommit(last_file.Get())) {
LogPrintf("%s: Failed to commit filter file %d\n", __func__, pos.nFile);
return 0;
}
pos.nFile++;
pos.nPos = 0;
}
// Pre-allocate sufficient space for filter data.
bool out_of_space;
m_filter_fileseq->Allocate(pos, data_size, out_of_space);
if (out_of_space) {
LogPrintf("%s: out of disk space\n", __func__);
return 0;
}
AutoFile fileout{m_filter_fileseq->Open(pos)};
if (fileout.IsNull()) {
LogPrintf("%s: Failed to open filter file %d\n", __func__, pos.nFile);
return 0;
}
fileout << filter.GetBlockHash() << filter.GetEncodedFilter();
return data_size;
}
std::optional<uint256> BlockFilterIndex::ReadFilterHeader(int height, const uint256& expected_block_hash)
{
std::pair<uint256, DBVal> read_out;
if (!m_db->Read(DBHeightKey(height), read_out)) {
return std::nullopt;
}
if (read_out.first != expected_block_hash) {
LogError("%s: previous block header belongs to unexpected block %s; expected %s\n",
__func__, read_out.first.ToString(), expected_block_hash.ToString());
return std::nullopt;
}
return read_out.second.header;
}
bool BlockFilterIndex::CustomAppend(const interfaces::BlockInfo& block)
{
CBlockUndo block_undo;
if (block.height > 0) {
// pindex variable gives indexing code access to node internals. It
// will be removed in upcoming commit
const CBlockIndex* pindex = WITH_LOCK(cs_main, return m_chainstate->m_blockman.LookupBlockIndex(block.hash));
if (!m_chainstate->m_blockman.UndoReadFromDisk(block_undo, *pindex)) {
return false;
}
}
BlockFilter filter(m_filter_type, *Assert(block.data), block_undo);
const uint256& header = filter.ComputeHeader(m_last_header);
bool res = Write(filter, block.height, header);
if (res) m_last_header = header; // update last header
return res;
}
bool BlockFilterIndex::Write(const BlockFilter& filter, uint32_t block_height, const uint256& filter_header)
{
size_t bytes_written = WriteFilterToDisk(m_next_filter_pos, filter);
if (bytes_written == 0) return false;
std::pair<uint256, DBVal> value;
value.first = filter.GetBlockHash();
value.second.hash = filter.GetHash();
value.second.header = filter_header;
value.second.pos = m_next_filter_pos;
if (!m_db->Write(DBHeightKey(block_height), value)) {
return false;
}
m_next_filter_pos.nPos += bytes_written;
return true;
}
[[nodiscard]] static bool CopyHeightIndexToHashIndex(CDBIterator& db_it, CDBBatch& batch,
const std::string& index_name,
int start_height, int stop_height)
{
DBHeightKey key(start_height);
db_it.Seek(key);
for (int height = start_height; height <= stop_height; ++height) {
if (!db_it.GetKey(key) || key.height != height) {
LogError("%s: unexpected key in %s: expected (%c, %d)\n",
__func__, index_name, DB_BLOCK_HEIGHT, height);
return false;
}
std::pair<uint256, DBVal> value;
if (!db_it.GetValue(value)) {
LogError("%s: unable to read value in %s at key (%c, %d)\n",
__func__, index_name, DB_BLOCK_HEIGHT, height);
return false;
}
batch.Write(DBHashKey(value.first), std::move(value.second));
db_it.Next();
}
return true;
}
bool BlockFilterIndex::CustomRewind(const interfaces::BlockKey& current_tip, const interfaces::BlockKey& new_tip)
{
CDBBatch batch(*m_db);
std::unique_ptr<CDBIterator> db_it(m_db->NewIterator());
// During a reorg, we need to copy all filters for blocks that are getting disconnected from the
// height index to the hash index so we can still find them when the height index entries are
// overwritten.
if (!CopyHeightIndexToHashIndex(*db_it, batch, m_name, new_tip.height, current_tip.height)) {
return false;
}
// The latest filter position gets written in Commit by the call to the BaseIndex::Rewind.
// But since this creates new references to the filter, the position should get updated here
// atomically as well in case Commit fails.
batch.Write(DB_FILTER_POS, m_next_filter_pos);
if (!m_db->WriteBatch(batch)) return false;
// Update cached header
m_last_header = *Assert(ReadFilterHeader(new_tip.height, new_tip.hash));
return true;
}
static bool LookupOne(const CDBWrapper& db, const CBlockIndex* block_index, DBVal& result)
{
// First check if the result is stored under the height index and the value there matches the
// block hash. This should be the case if the block is on the active chain.
std::pair<uint256, DBVal> read_out;
if (!db.Read(DBHeightKey(block_index->nHeight), read_out)) {
return false;
}
if (read_out.first == block_index->GetBlockHash()) {
result = std::move(read_out.second);
return true;
}
// If value at the height index corresponds to an different block, the result will be stored in
// the hash index.
return db.Read(DBHashKey(block_index->GetBlockHash()), result);
}
static bool LookupRange(CDBWrapper& db, const std::string& index_name, int start_height,
const CBlockIndex* stop_index, std::vector<DBVal>& results)
{
if (start_height < 0) {
LogError("%s: start height (%d) is negative\n", __func__, start_height);
return false;
}
if (start_height > stop_index->nHeight) {
LogError("%s: start height (%d) is greater than stop height (%d)\n",
__func__, start_height, stop_index->nHeight);
return false;
}
size_t results_size = static_cast<size_t>(stop_index->nHeight - start_height + 1);
std::vector<std::pair<uint256, DBVal>> values(results_size);
DBHeightKey key(start_height);
std::unique_ptr<CDBIterator> db_it(db.NewIterator());
db_it->Seek(DBHeightKey(start_height));
for (int height = start_height; height <= stop_index->nHeight; ++height) {
if (!db_it->Valid() || !db_it->GetKey(key) || key.height != height) {
return false;
}
size_t i = static_cast<size_t>(height - start_height);
if (!db_it->GetValue(values[i])) {
LogError("%s: unable to read value in %s at key (%c, %d)\n",
__func__, index_name, DB_BLOCK_HEIGHT, height);
return false;
}
db_it->Next();
}
results.resize(results_size);
// Iterate backwards through block indexes collecting results in order to access the block hash
// of each entry in case we need to look it up in the hash index.
for (const CBlockIndex* block_index = stop_index;
block_index && block_index->nHeight >= start_height;
block_index = block_index->pprev) {
uint256 block_hash = block_index->GetBlockHash();
size_t i = static_cast<size_t>(block_index->nHeight - start_height);
if (block_hash == values[i].first) {
results[i] = std::move(values[i].second);
continue;
}
if (!db.Read(DBHashKey(block_hash), results[i])) {
LogError("%s: unable to read value in %s at key (%c, %s)\n",
__func__, index_name, DB_BLOCK_HASH, block_hash.ToString());
return false;
}
}
return true;
}
bool BlockFilterIndex::LookupFilter(const CBlockIndex* block_index, BlockFilter& filter_out) const
{
DBVal entry;
if (!LookupOne(*m_db, block_index, entry)) {
return false;
}
return ReadFilterFromDisk(entry.pos, entry.hash, filter_out);
}
bool BlockFilterIndex::LookupFilterHeader(const CBlockIndex* block_index, uint256& header_out)
{
LOCK(m_cs_headers_cache);
bool is_checkpoint{block_index->nHeight % CFCHECKPT_INTERVAL == 0};
if (is_checkpoint) {
// Try to find the block in the headers cache if this is a checkpoint height.
auto header = m_headers_cache.find(block_index->GetBlockHash());
if (header != m_headers_cache.end()) {
header_out = header->second;
return true;
}
}
DBVal entry;
if (!LookupOne(*m_db, block_index, entry)) {
return false;
}
if (is_checkpoint &&
m_headers_cache.size() < CF_HEADERS_CACHE_MAX_SZ) {
// Add to the headers cache if this is a checkpoint height.
m_headers_cache.emplace(block_index->GetBlockHash(), entry.header);
}
header_out = entry.header;
return true;
}
bool BlockFilterIndex::LookupFilterRange(int start_height, const CBlockIndex* stop_index,
std::vector<BlockFilter>& filters_out) const
{
std::vector<DBVal> entries;
if (!LookupRange(*m_db, m_name, start_height, stop_index, entries)) {
return false;
}
filters_out.resize(entries.size());
auto filter_pos_it = filters_out.begin();
for (const auto& entry : entries) {
if (!ReadFilterFromDisk(entry.pos, entry.hash, *filter_pos_it)) {
return false;
}
++filter_pos_it;
}
return true;
}
bool BlockFilterIndex::LookupFilterHashRange(int start_height, const CBlockIndex* stop_index,
std::vector<uint256>& hashes_out) const
{
std::vector<DBVal> entries;
if (!LookupRange(*m_db, m_name, start_height, stop_index, entries)) {
return false;
}
hashes_out.clear();
hashes_out.reserve(entries.size());
for (const auto& entry : entries) {
hashes_out.push_back(entry.hash);
}
return true;
}
BlockFilterIndex* GetBlockFilterIndex(BlockFilterType filter_type)
{
auto it = g_filter_indexes.find(filter_type);
return it != g_filter_indexes.end() ? &it->second : nullptr;
}
void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn)
{
for (auto& entry : g_filter_indexes) fn(entry.second);
}
bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
size_t n_cache_size, bool f_memory, bool f_wipe)
{
auto result = g_filter_indexes.emplace(std::piecewise_construct,
std::forward_as_tuple(filter_type),
std::forward_as_tuple(make_chain(), filter_type,
n_cache_size, f_memory, f_wipe));
return result.second;
}
bool DestroyBlockFilterIndex(BlockFilterType filter_type)
{
return g_filter_indexes.erase(filter_type);
}
void DestroyAllBlockFilterIndexes()
{
g_filter_indexes.clear();
}
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