mirror of
https://github.com/facebook/rocksdb.git
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6fbd02f258
Summary: Fixes https://github.com/facebook/rocksdb/issues/12501 Pull Request resolved: https://github.com/facebook/rocksdb/pull/12500 Reviewed By: jowlyzhang Differential Revision: D55922379 Pulled By: ajkr fbshipit-source-id: 0759afcec148d256a2d1cd5ef76fd988fab4a9af
390 lines
13 KiB
C++
390 lines
13 KiB
C++
// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include "utilities/cache_dump_load_impl.h"
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#include <limits>
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#include "cache/cache_entry_roles.h"
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#include "cache/cache_key.h"
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#include "file/writable_file_writer.h"
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#include "port/lang.h"
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#include "rocksdb/env.h"
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#include "rocksdb/file_system.h"
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#include "rocksdb/utilities/ldb_cmd.h"
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#include "table/block_based/block_based_table_reader.h"
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#include "table/format.h"
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#include "util/crc32c.h"
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namespace ROCKSDB_NAMESPACE {
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// Set the dump filter with a list of DBs. Block cache may be shared by multipe
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// DBs and we may only want to dump out the blocks belonging to certain DB(s).
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// Therefore, a filter is need to decide if the key of the block satisfy the
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// requirement.
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Status CacheDumperImpl::SetDumpFilter(std::vector<DB*> db_list) {
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Status s = Status::OK();
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dump_all_keys_ = false;
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for (size_t i = 0; i < db_list.size(); i++) {
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assert(i < db_list.size());
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TablePropertiesCollection ptc;
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assert(db_list[i] != nullptr);
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s = db_list[i]->GetPropertiesOfAllTables(&ptc);
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if (!s.ok()) {
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return s;
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}
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for (auto id = ptc.begin(); id != ptc.end(); id++) {
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OffsetableCacheKey base;
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// We only want to save cache entries that are portable to another
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// DB::Open, so only save entries with stable keys.
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bool is_stable;
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BlockBasedTable::SetupBaseCacheKey(id->second.get(),
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/*cur_db_session_id*/ "",
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/*cur_file_num*/ 0, &base, &is_stable);
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if (is_stable) {
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Slice prefix_slice = base.CommonPrefixSlice();
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assert(prefix_slice.size() == OffsetableCacheKey::kCommonPrefixSize);
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prefix_filter_.insert(prefix_slice.ToString());
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}
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}
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}
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return s;
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}
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// This is the main function to dump out the cache block entries to the writer.
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// The writer may create a file or write to other systems. Currently, we will
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// iterate the whole block cache, get the blocks, and write them to the writer
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IOStatus CacheDumperImpl::DumpCacheEntriesToWriter() {
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// Prepare stage, check the parameters.
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if (cache_ == nullptr) {
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return IOStatus::InvalidArgument("Cache is null");
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}
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if (writer_ == nullptr) {
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return IOStatus::InvalidArgument("CacheDumpWriter is null");
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}
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// Set the system clock
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if (options_.clock == nullptr) {
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return IOStatus::InvalidArgument("System clock is null");
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}
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clock_ = options_.clock;
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deadline_ = options_.deadline;
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// Set the sequence number
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sequence_num_ = 0;
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// Dump stage, first, we write the hader
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IOStatus io_s = WriteHeader();
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if (!io_s.ok()) {
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return io_s;
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}
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// Then, we iterate the block cache and dump out the blocks that are not
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// filtered out.
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std::string buf;
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cache_->ApplyToAllEntries(DumpOneBlockCallBack(buf), {});
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// Finally, write the footer
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io_s = WriteFooter();
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if (!io_s.ok()) {
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return io_s;
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}
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io_s = writer_->Close();
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return io_s;
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}
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// Check if we need to filter out the block based on its key
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bool CacheDumperImpl::ShouldFilterOut(const Slice& key) {
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if (key.size() < OffsetableCacheKey::kCommonPrefixSize) {
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return /*filter out*/ true;
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}
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Slice key_prefix(key.data(), OffsetableCacheKey::kCommonPrefixSize);
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std::string prefix = key_prefix.ToString();
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// Filter out if not found
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return prefix_filter_.find(prefix) == prefix_filter_.end();
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}
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// This is the callback function which will be applied to
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// Cache::ApplyToAllEntries. In this callback function, we will get the block
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// type, decide if the block needs to be dumped based on the filter, and write
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// the block through the provided writer. `buf` is passed in for efficiennt
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// reuse.
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std::function<void(const Slice&, Cache::ObjectPtr, size_t,
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const Cache::CacheItemHelper*)>
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CacheDumperImpl::DumpOneBlockCallBack(std::string& buf) {
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return [&](const Slice& key, Cache::ObjectPtr value, size_t /*charge*/,
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const Cache::CacheItemHelper* helper) {
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if (helper == nullptr || helper->size_cb == nullptr ||
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helper->saveto_cb == nullptr) {
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// Not compatible with dumping. Skip this entry.
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return;
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}
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if (options_.max_size_bytes > 0 &&
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dumped_size_bytes_ > options_.max_size_bytes) {
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return;
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}
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uint64_t timestamp = clock_->NowMicros();
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if (deadline_.count()) {
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std::chrono::microseconds now = std::chrono::microseconds(timestamp);
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if (now >= deadline_) {
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return;
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}
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}
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CacheEntryRole role = helper->role;
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CacheDumpUnitType type = CacheDumpUnitType::kBlockTypeMax;
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switch (role) {
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case CacheEntryRole::kDataBlock:
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type = CacheDumpUnitType::kData;
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break;
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case CacheEntryRole::kFilterBlock:
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type = CacheDumpUnitType::kFilter;
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break;
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case CacheEntryRole::kFilterMetaBlock:
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type = CacheDumpUnitType::kFilterMetaBlock;
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break;
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case CacheEntryRole::kIndexBlock:
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type = CacheDumpUnitType::kIndex;
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break;
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default:
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// Filter out other entries
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// FIXME? Do we need the CacheDumpUnitTypes? UncompressionDict?
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return;
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}
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// based on the key prefix, check if the block should be filter out.
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if (!dump_all_keys_ && ShouldFilterOut(key)) {
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return;
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}
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assert(type != CacheDumpUnitType::kBlockTypeMax);
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// Use cache item helper to get persistable data
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// FIXME: reduce copying
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size_t len = helper->size_cb(value);
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buf.assign(len, '\0');
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Status s = helper->saveto_cb(value, /*start*/ 0, len, buf.data());
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if (s.ok()) {
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// Write it out
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WriteBlock(type, key, buf, timestamp).PermitUncheckedError();
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dumped_size_bytes_ += len;
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}
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};
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}
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// Write the block to the writer. It takes the timestamp of the
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// block being copied from block cache, block type, key, block pointer,
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// block size and block checksum as the input. When writing the dumper raw
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// block, we first create the dump unit and encoude it to a string. Then,
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// we calculate the checksum of the whole dump unit string and store it in
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// the dump unit metadata.
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// First, we write the metadata first, which is a fixed size string. Then, we
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// Append the dump unit string to the writer.
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IOStatus CacheDumperImpl::WriteBlock(CacheDumpUnitType type, const Slice& key,
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const Slice& value, uint64_t timestamp) {
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uint32_t value_checksum = crc32c::Value(value.data(), value.size());
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// First, serialize the block information in a string
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DumpUnit dump_unit;
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dump_unit.timestamp = timestamp;
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dump_unit.key = key;
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dump_unit.type = type;
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dump_unit.value_len = value.size();
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dump_unit.value = const_cast<char*>(value.data());
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dump_unit.value_checksum = value_checksum;
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std::string encoded_data;
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CacheDumperHelper::EncodeDumpUnit(dump_unit, &encoded_data);
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// Second, create the metadata, which contains a sequence number, the dump
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// unit string checksum and the string size. The sequence number monotonically
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// increases from 0.
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DumpUnitMeta unit_meta;
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unit_meta.sequence_num = sequence_num_;
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sequence_num_++;
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unit_meta.dump_unit_checksum =
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crc32c::Value(encoded_data.data(), encoded_data.size());
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unit_meta.dump_unit_size = encoded_data.size();
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std::string encoded_meta;
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CacheDumperHelper::EncodeDumpUnitMeta(unit_meta, &encoded_meta);
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// We write the metadata first.
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assert(writer_ != nullptr);
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IOStatus io_s = writer_->WriteMetadata(encoded_meta);
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if (!io_s.ok()) {
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return io_s;
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}
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// followed by the dump unit.
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return writer_->WritePacket(encoded_data);
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}
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// Before we write any block, we write the header first to store the cache dump
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// format version, rocksdb version, and brief intro.
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IOStatus CacheDumperImpl::WriteHeader() {
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std::string header_key = "header";
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std::ostringstream s;
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s << kTraceMagic << "\t"
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<< "Cache dump format version: " << kCacheDumpMajorVersion << "."
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<< kCacheDumpMinorVersion << "\t"
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<< "RocksDB Version: " << kMajorVersion << "." << kMinorVersion << "\t"
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<< "Format: dump_unit_metadata <sequence_number, dump_unit_checksum, "
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"dump_unit_size>, dump_unit <timestamp, key, block_type, "
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"block_size, block_data, block_checksum> cache_value\n";
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std::string header_value(s.str());
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CacheDumpUnitType type = CacheDumpUnitType::kHeader;
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uint64_t timestamp = clock_->NowMicros();
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return WriteBlock(type, header_key, header_value, timestamp);
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}
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// Write the footer after all the blocks are stored to indicate the ending.
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IOStatus CacheDumperImpl::WriteFooter() {
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std::string footer_key = "footer";
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std::string footer_value("cache dump completed");
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CacheDumpUnitType type = CacheDumpUnitType::kFooter;
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uint64_t timestamp = clock_->NowMicros();
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return WriteBlock(type, footer_key, footer_value, timestamp);
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}
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// This is the main function to restore the cache entries to secondary cache.
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// First, we check if all the arguments are valid. Then, we read the block
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// sequentially from the reader and insert them to the secondary cache.
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IOStatus CacheDumpedLoaderImpl::RestoreCacheEntriesToSecondaryCache() {
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// TODO: remove this line when options are used in the loader
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(void)options_;
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// Step 1: we check if all the arguments are valid
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if (secondary_cache_ == nullptr) {
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return IOStatus::InvalidArgument("Secondary Cache is null");
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}
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if (reader_ == nullptr) {
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return IOStatus::InvalidArgument("CacheDumpReader is null");
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}
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// Step 2: read the header
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// TODO: we need to check the cache dump format version and RocksDB version
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// after the header is read out.
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IOStatus io_s;
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DumpUnit dump_unit;
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std::string data;
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io_s = ReadHeader(&data, &dump_unit);
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if (!io_s.ok()) {
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return io_s;
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}
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// Step 3: read out the rest of the blocks from the reader. The loop will stop
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// either I/O status is not ok or we reach to the the end.
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while (io_s.ok()) {
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dump_unit.reset();
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data.clear();
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// read the content and store in the dump_unit
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io_s = ReadCacheBlock(&data, &dump_unit);
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if (!io_s.ok()) {
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break;
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}
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if (dump_unit.type == CacheDumpUnitType::kFooter) {
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break;
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}
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// Create the uncompressed_block based on the information in the dump_unit
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// (There is no block trailer here compatible with block-based SST file.)
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Slice content =
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Slice(static_cast<char*>(dump_unit.value), dump_unit.value_len);
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Status s = secondary_cache_->InsertSaved(dump_unit.key, content);
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if (!s.ok()) {
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io_s = status_to_io_status(std::move(s));
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}
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}
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if (dump_unit.type == CacheDumpUnitType::kFooter) {
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return IOStatus::OK();
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} else {
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return io_s;
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}
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}
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// Read and copy the dump unit metadata to std::string data, decode and create
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// the unit metadata based on the string
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IOStatus CacheDumpedLoaderImpl::ReadDumpUnitMeta(std::string* data,
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DumpUnitMeta* unit_meta) {
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assert(reader_ != nullptr);
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assert(data != nullptr);
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assert(unit_meta != nullptr);
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IOStatus io_s = reader_->ReadMetadata(data);
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if (!io_s.ok()) {
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return io_s;
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}
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return status_to_io_status(
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CacheDumperHelper::DecodeDumpUnitMeta(*data, unit_meta));
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}
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// Read and copy the dump unit to std::string data, decode and create the unit
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// based on the string
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IOStatus CacheDumpedLoaderImpl::ReadDumpUnit(size_t len, std::string* data,
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DumpUnit* unit) {
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assert(reader_ != nullptr);
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assert(data != nullptr);
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assert(unit != nullptr);
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IOStatus io_s = reader_->ReadPacket(data);
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if (!io_s.ok()) {
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return io_s;
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}
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if (data->size() != len) {
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return IOStatus::Corruption(
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"The data being read out does not match the size stored in metadata!");
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}
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Slice block;
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return status_to_io_status(CacheDumperHelper::DecodeDumpUnit(*data, unit));
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}
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// Read the header
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IOStatus CacheDumpedLoaderImpl::ReadHeader(std::string* data,
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DumpUnit* dump_unit) {
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DumpUnitMeta header_meta;
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header_meta.reset();
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std::string meta_string;
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IOStatus io_s = ReadDumpUnitMeta(&meta_string, &header_meta);
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if (!io_s.ok()) {
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return io_s;
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}
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io_s = ReadDumpUnit(header_meta.dump_unit_size, data, dump_unit);
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if (!io_s.ok()) {
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return io_s;
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}
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uint32_t unit_checksum = crc32c::Value(data->data(), data->size());
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if (unit_checksum != header_meta.dump_unit_checksum) {
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return IOStatus::Corruption("Read header unit corrupted!");
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}
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return io_s;
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}
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// Read the blocks after header is read out
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IOStatus CacheDumpedLoaderImpl::ReadCacheBlock(std::string* data,
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DumpUnit* dump_unit) {
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// According to the write process, we read the dump_unit_metadata first
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DumpUnitMeta unit_meta;
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unit_meta.reset();
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std::string unit_string;
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IOStatus io_s = ReadDumpUnitMeta(&unit_string, &unit_meta);
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if (!io_s.ok()) {
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return io_s;
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}
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// Based on the information in the dump_unit_metadata, we read the dump_unit
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// and verify if its content is correct.
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io_s = ReadDumpUnit(unit_meta.dump_unit_size, data, dump_unit);
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if (!io_s.ok()) {
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return io_s;
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}
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uint32_t unit_checksum = crc32c::Value(data->data(), data->size());
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if (unit_checksum != unit_meta.dump_unit_checksum) {
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return IOStatus::Corruption(
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"Checksum does not match! Read dumped unit corrupted!");
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}
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return io_s;
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}
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} // namespace ROCKSDB_NAMESPACE
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