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rocksdb/utilities/cache_dump_load_impl.cc

393 lines
14 KiB

// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "cache/cache_key.h"
#include "table/block_based/block_based_table_reader.h"
#ifndef ROCKSDB_LITE
#include "cache/cache_entry_roles.h"
#include "file/writable_file_writer.h"
#include "port/lang.h"
#include "rocksdb/env.h"
#include "rocksdb/file_system.h"
#include "rocksdb/utilities/ldb_cmd.h"
#include "table/format.h"
#include "util/crc32c.h"
#include "utilities/cache_dump_load_impl.h"
namespace ROCKSDB_NAMESPACE {
// Set the dump filter with a list of DBs. Block cache may be shared by multipe
// DBs and we may only want to dump out the blocks belonging to certain DB(s).
// Therefore, a filter is need to decide if the key of the block satisfy the
// requirement.
Status CacheDumperImpl::SetDumpFilter(std::vector<DB*> db_list) {
Status s = Status::OK();
for (size_t i = 0; i < db_list.size(); i++) {
assert(i < db_list.size());
TablePropertiesCollection ptc;
assert(db_list[i] != nullptr);
s = db_list[i]->GetPropertiesOfAllTables(&ptc);
if (!s.ok()) {
return s;
}
for (auto id = ptc.begin(); id != ptc.end(); id++) {
OffsetableCacheKey base;
// We only want to save cache entries that are portable to another
// DB::Open, so only save entries with stable keys.
bool is_stable;
BlockBasedTable::SetupBaseCacheKey(id->second.get(),
/*cur_db_session_id*/ "",
/*cur_file_num*/ 0, &base, &is_stable);
if (is_stable) {
Slice prefix_slice = base.CommonPrefixSlice();
assert(prefix_slice.size() == OffsetableCacheKey::kCommonPrefixSize);
prefix_filter_.insert(prefix_slice.ToString());
}
}
}
return s;
}
// This is the main function to dump out the cache block entries to the writer.
// The writer may create a file or write to other systems. Currently, we will
// iterate the whole block cache, get the blocks, and write them to the writer
IOStatus CacheDumperImpl::DumpCacheEntriesToWriter() {
// Prepare stage, check the parameters.
if (cache_ == nullptr) {
return IOStatus::InvalidArgument("Cache is null");
}
if (writer_ == nullptr) {
return IOStatus::InvalidArgument("CacheDumpWriter is null");
}
// Set the system clock
if (options_.clock == nullptr) {
return IOStatus::InvalidArgument("System clock is null");
}
clock_ = options_.clock;
// We copy the Cache Deleter Role Map as its member.
role_map_ = CopyCacheDeleterRoleMap();
// Set the sequence number
sequence_num_ = 0;
// Dump stage, first, we write the hader
IOStatus io_s = WriteHeader();
if (!io_s.ok()) {
return io_s;
}
// Then, we iterate the block cache and dump out the blocks that are not
// filtered out.
cache_->ApplyToAllEntries(DumpOneBlockCallBack(), {});
// Finally, write the footer
io_s = WriteFooter();
if (!io_s.ok()) {
return io_s;
}
io_s = writer_->Close();
return io_s;
}
// Check if we need to filter out the block based on its key
bool CacheDumperImpl::ShouldFilterOut(const Slice& key) {
if (key.size() < OffsetableCacheKey::kCommonPrefixSize) {
return /*filter out*/ true;
}
Slice key_prefix(key.data(), OffsetableCacheKey::kCommonPrefixSize);
std::string prefix = key_prefix.ToString();
// Filter out if not found
return prefix_filter_.find(prefix) == prefix_filter_.end();
}
// This is the callback function which will be applied to
// Cache::ApplyToAllEntries. In this callback function, we will get the block
// type, decide if the block needs to be dumped based on the filter, and write
// the block through the provided writer.
std::function<void(const Slice&, void*, size_t, Cache::DeleterFn)>
CacheDumperImpl::DumpOneBlockCallBack() {
return [&](const Slice& key, void* value, size_t /*charge*/,
Cache::DeleterFn deleter) {
// Step 1: get the type of the block from role_map_
auto e = role_map_.find(deleter);
CacheEntryRole role;
CacheDumpUnitType type = CacheDumpUnitType::kBlockTypeMax;
if (e == role_map_.end()) {
role = CacheEntryRole::kMisc;
} else {
role = e->second;
}
bool filter_out = false;
// Step 2: based on the key prefix, check if the block should be filter out.
if (ShouldFilterOut(key)) {
filter_out = true;
}
// Step 3: based on the block type, get the block raw pointer and length.
const char* block_start = nullptr;
size_t block_len = 0;
switch (role) {
case CacheEntryRole::kDataBlock:
type = CacheDumpUnitType::kData;
block_start = (static_cast<Block*>(value))->data();
block_len = (static_cast<Block*>(value))->size();
break;
case CacheEntryRole::kFilterBlock:
type = CacheDumpUnitType::kFilter;
block_start = (static_cast<ParsedFullFilterBlock*>(value))
->GetBlockContentsData()
.data();
block_len = (static_cast<ParsedFullFilterBlock*>(value))
->GetBlockContentsData()
.size();
break;
case CacheEntryRole::kFilterMetaBlock:
type = CacheDumpUnitType::kFilterMetaBlock;
block_start = (static_cast<Block*>(value))->data();
block_len = (static_cast<Block*>(value))->size();
break;
case CacheEntryRole::kIndexBlock:
type = CacheDumpUnitType::kIndex;
block_start = (static_cast<Block*>(value))->data();
block_len = (static_cast<Block*>(value))->size();
break;
case CacheEntryRole::kDeprecatedFilterBlock:
// Obsolete
filter_out = true;
break;
case CacheEntryRole::kMisc:
filter_out = true;
break;
case CacheEntryRole::kOtherBlock:
filter_out = true;
break;
case CacheEntryRole::kWriteBuffer:
filter_out = true;
break;
default:
filter_out = true;
}
// Step 4: if the block should not be filter out, write the block to the
// CacheDumpWriter
if (!filter_out && block_start != nullptr) {
WriteBlock(type, key, Slice(block_start, block_len))
.PermitUncheckedError();
}
};
}
// Write the block to the writer. It takes the timestamp of the
// block being copied from block cache, block type, key, block pointer,
// block size and block checksum as the input. When writing the dumper raw
// block, we first create the dump unit and encoude it to a string. Then,
// we calculate the checksum of the whole dump unit string and store it in
// the dump unit metadata.
// First, we write the metadata first, which is a fixed size string. Then, we
// Append the dump unit string to the writer.
IOStatus CacheDumperImpl::WriteBlock(CacheDumpUnitType type, const Slice& key,
const Slice& value) {
uint64_t timestamp = clock_->NowMicros();
uint32_t value_checksum = crc32c::Value(value.data(), value.size());
// First, serialize the block information in a string
DumpUnit dump_unit;
dump_unit.timestamp = timestamp;
dump_unit.key = key;
dump_unit.type = type;
dump_unit.value_len = value.size();
dump_unit.value = const_cast<char*>(value.data());
dump_unit.value_checksum = value_checksum;
std::string encoded_data;
CacheDumperHelper::EncodeDumpUnit(dump_unit, &encoded_data);
// Second, create the metadata, which contains a sequence number, the dump
// unit string checksum and the string size. The sequence number monotonically
// increases from 0.
DumpUnitMeta unit_meta;
unit_meta.sequence_num = sequence_num_;
sequence_num_++;
unit_meta.dump_unit_checksum =
crc32c::Value(encoded_data.data(), encoded_data.size());
unit_meta.dump_unit_size = encoded_data.size();
std::string encoded_meta;
CacheDumperHelper::EncodeDumpUnitMeta(unit_meta, &encoded_meta);
// We write the metadata first.
assert(writer_ != nullptr);
IOStatus io_s = writer_->WriteMetadata(encoded_meta);
if (!io_s.ok()) {
return io_s;
}
// followed by the dump unit.
return writer_->WritePacket(encoded_data);
}
// Before we write any block, we write the header first to store the cache dump
// format version, rocksdb version, and brief intro.
IOStatus CacheDumperImpl::WriteHeader() {
std::string header_key = "header";
std::ostringstream s;
s << kTraceMagic << "\t"
<< "Cache dump format version: " << kCacheDumpMajorVersion << "."
<< kCacheDumpMinorVersion << "\t"
<< "RocksDB Version: " << kMajorVersion << "." << kMinorVersion << "\t"
<< "Format: dump_unit_metadata <sequence_number, dump_unit_checksum, "
"dump_unit_size>, dump_unit <timestamp, key, block_type, "
"block_size, block_data, block_checksum> cache_value\n";
std::string header_value(s.str());
CacheDumpUnitType type = CacheDumpUnitType::kHeader;
return WriteBlock(type, header_key, header_value);
}
// Write the footer after all the blocks are stored to indicate the ending.
IOStatus CacheDumperImpl::WriteFooter() {
std::string footer_key = "footer";
std::string footer_value("cache dump completed");
CacheDumpUnitType type = CacheDumpUnitType::kFooter;
return WriteBlock(type, footer_key, footer_value);
}
// This is the main function to restore the cache entries to secondary cache.
// First, we check if all the arguments are valid. Then, we read the block
// sequentially from the reader and insert them to the secondary cache.
IOStatus CacheDumpedLoaderImpl::RestoreCacheEntriesToSecondaryCache() {
// TODO: remove this line when options are used in the loader
(void)options_;
// Step 1: we check if all the arguments are valid
if (secondary_cache_ == nullptr) {
return IOStatus::InvalidArgument("Secondary Cache is null");
}
if (reader_ == nullptr) {
return IOStatus::InvalidArgument("CacheDumpReader is null");
}
// we copy the Cache Deleter Role Map as its member.
role_map_ = CopyCacheDeleterRoleMap();
// Step 2: read the header
// TODO: we need to check the cache dump format version and RocksDB version
// after the header is read out.
IOStatus io_s;
DumpUnit dump_unit;
std::string data;
io_s = ReadHeader(&data, &dump_unit);
if (!io_s.ok()) {
return io_s;
}
// Step 3: read out the rest of the blocks from the reader. The loop will stop
// either I/O status is not ok or we reach to the the end.
while (io_s.ok()) {
dump_unit.reset();
data.clear();
// read the content and store in the dump_unit
io_s = ReadCacheBlock(&data, &dump_unit);
if (!io_s.ok()) {
break;
}
if (dump_unit.type == CacheDumpUnitType::kFooter) {
break;
}
// Create the uncompressed_block based on the information in the dump_unit
// (There is no block trailer here compatible with block-based SST file.)
Slice content =
Slice(static_cast<char*>(dump_unit.value), dump_unit.value_len);
Status s = secondary_cache_->InsertSaved(dump_unit.key, content);
if (!s.ok()) {
io_s = status_to_io_status(std::move(s));
}
}
if (dump_unit.type == CacheDumpUnitType::kFooter) {
return IOStatus::OK();
} else {
return io_s;
}
}
// Read and copy the dump unit metadata to std::string data, decode and create
// the unit metadata based on the string
IOStatus CacheDumpedLoaderImpl::ReadDumpUnitMeta(std::string* data,
DumpUnitMeta* unit_meta) {
assert(reader_ != nullptr);
assert(data != nullptr);
assert(unit_meta != nullptr);
IOStatus io_s = reader_->ReadMetadata(data);
if (!io_s.ok()) {
return io_s;
}
return status_to_io_status(
CacheDumperHelper::DecodeDumpUnitMeta(*data, unit_meta));
}
// Read and copy the dump unit to std::string data, decode and create the unit
// based on the string
IOStatus CacheDumpedLoaderImpl::ReadDumpUnit(size_t len, std::string* data,
DumpUnit* unit) {
assert(reader_ != nullptr);
assert(data != nullptr);
assert(unit != nullptr);
IOStatus io_s = reader_->ReadPacket(data);
if (!io_s.ok()) {
return io_s;
}
if (data->size() != len) {
return IOStatus::Corruption(
"The data being read out does not match the size stored in metadata!");
}
Slice block;
return status_to_io_status(CacheDumperHelper::DecodeDumpUnit(*data, unit));
}
// Read the header
IOStatus CacheDumpedLoaderImpl::ReadHeader(std::string* data,
DumpUnit* dump_unit) {
DumpUnitMeta header_meta;
header_meta.reset();
std::string meta_string;
IOStatus io_s = ReadDumpUnitMeta(&meta_string, &header_meta);
if (!io_s.ok()) {
return io_s;
}
io_s = ReadDumpUnit(header_meta.dump_unit_size, data, dump_unit);
if (!io_s.ok()) {
return io_s;
}
uint32_t unit_checksum = crc32c::Value(data->data(), data->size());
if (unit_checksum != header_meta.dump_unit_checksum) {
return IOStatus::Corruption("Read header unit corrupted!");
}
return io_s;
}
// Read the blocks after header is read out
IOStatus CacheDumpedLoaderImpl::ReadCacheBlock(std::string* data,
DumpUnit* dump_unit) {
// According to the write process, we read the dump_unit_metadata first
DumpUnitMeta unit_meta;
unit_meta.reset();
std::string unit_string;
IOStatus io_s = ReadDumpUnitMeta(&unit_string, &unit_meta);
if (!io_s.ok()) {
return io_s;
}
// Based on the information in the dump_unit_metadata, we read the dump_unit
// and verify if its content is correct.
io_s = ReadDumpUnit(unit_meta.dump_unit_size, data, dump_unit);
if (!io_s.ok()) {
return io_s;
}
uint32_t unit_checksum = crc32c::Value(data->data(), data->size());
if (unit_checksum != unit_meta.dump_unit_checksum) {
return IOStatus::Corruption(
"Checksum does not match! Read dumped unit corrupted!");
}
return io_s;
}
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE