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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:54:28 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:54:28 +0000 |
commit | e6918187568dbd01842d8d1d2c808ce16a894239 (patch) | |
tree | 64f88b554b444a49f656b6c656111a145cbbaa28 /src/rocksdb/trace_replay/block_cache_tracer.h | |
parent | Initial commit. (diff) | |
download | ceph-upstream/18.2.2.tar.xz ceph-upstream/18.2.2.zip |
Adding upstream version 18.2.2.upstream/18.2.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/rocksdb/trace_replay/block_cache_tracer.h | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/src/rocksdb/trace_replay/block_cache_tracer.h b/src/rocksdb/trace_replay/block_cache_tracer.h new file mode 100644 index 000000000..4a749608f --- /dev/null +++ b/src/rocksdb/trace_replay/block_cache_tracer.h @@ -0,0 +1,239 @@ +// Copyright (c) 2011-present, Facebook, Inc. 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). + +#pragma once + +#include <atomic> +#include <fstream> + +#include "monitoring/instrumented_mutex.h" +#include "rocksdb/block_cache_trace_writer.h" +#include "rocksdb/options.h" +#include "rocksdb/table_reader_caller.h" +#include "rocksdb/trace_reader_writer.h" +#include "trace_replay/trace_replay.h" + +namespace ROCKSDB_NAMESPACE { +class Env; +class SystemClock; + +extern const uint64_t kMicrosInSecond; +extern const uint64_t kSecondInMinute; +extern const uint64_t kSecondInHour; + +struct BlockCacheTraceRecord; + +class BlockCacheTraceHelper { + public: + static bool IsGetOrMultiGetOnDataBlock(TraceType block_type, + TableReaderCaller caller); + static bool IsGetOrMultiGet(TableReaderCaller caller); + static bool IsUserAccess(TableReaderCaller caller); + // Row key is a concatenation of the access's fd_number and the referenced + // user key. + static std::string ComputeRowKey(const BlockCacheTraceRecord& access); + // The first four bytes of the referenced key in a Get request is the table + // id. + static uint64_t GetTableId(const BlockCacheTraceRecord& access); + // The sequence number of a get request is the last part of the referenced + // key. + static uint64_t GetSequenceNumber(const BlockCacheTraceRecord& access); + // Block offset in a file is the last varint64 in the block key. + static uint64_t GetBlockOffsetInFile(const BlockCacheTraceRecord& access); + + static const std::string kUnknownColumnFamilyName; + static const uint64_t kReservedGetId; +}; + +// Lookup context for tracing block cache accesses. +// We trace block accesses at five places: +// 1. BlockBasedTable::GetFilter +// 2. BlockBasedTable::GetUncompressedDict. +// 3. BlockBasedTable::MaybeReadAndLoadToCache. (To trace access on data, index, +// and range deletion block.) +// 4. BlockBasedTable::Get. (To trace the referenced key and whether the +// referenced key exists in a fetched data block.) +// 5. BlockBasedTable::MultiGet. (To trace the referenced key and whether the +// referenced key exists in a fetched data block.) +// The context is created at: +// 1. BlockBasedTable::Get. (kUserGet) +// 2. BlockBasedTable::MultiGet. (kUserMGet) +// 3. BlockBasedTable::NewIterator. (either kUserIterator, kCompaction, or +// external SST ingestion calls this function.) +// 4. BlockBasedTable::Open. (kPrefetch) +// 5. Index/Filter::CacheDependencies. (kPrefetch) +// 6. BlockBasedTable::ApproximateOffsetOf. (kCompaction or +// kUserApproximateSize). +struct BlockCacheLookupContext { + BlockCacheLookupContext(const TableReaderCaller& _caller) : caller(_caller) {} + BlockCacheLookupContext(const TableReaderCaller& _caller, uint64_t _get_id, + bool _get_from_user_specified_snapshot) + : caller(_caller), + get_id(_get_id), + get_from_user_specified_snapshot(_get_from_user_specified_snapshot) {} + const TableReaderCaller caller; + // These are populated when we perform lookup/insert on block cache. The block + // cache tracer uses these inforation when logging the block access at + // BlockBasedTable::GET and BlockBasedTable::MultiGet. + bool is_cache_hit = false; + bool no_insert = false; + TraceType block_type = TraceType::kTraceMax; + uint64_t block_size = 0; + std::string block_key; + uint64_t num_keys_in_block = 0; + // The unique id associated with Get and MultiGet. This enables us to track + // how many blocks a Get/MultiGet request accesses. We can also measure the + // impact of row cache vs block cache. + uint64_t get_id = 0; + std::string referenced_key; + bool get_from_user_specified_snapshot = false; + + void FillLookupContext(bool _is_cache_hit, bool _no_insert, + TraceType _block_type, uint64_t _block_size, + const std::string& _block_key, + uint64_t _num_keys_in_block) { + is_cache_hit = _is_cache_hit; + no_insert = _no_insert; + block_type = _block_type; + block_size = _block_size; + block_key = _block_key; + num_keys_in_block = _num_keys_in_block; + } +}; + +struct BlockCacheTraceHeader { + uint64_t start_time; + uint32_t rocksdb_major_version; + uint32_t rocksdb_minor_version; +}; + +// BlockCacheTraceWriter captures all RocksDB block cache accesses using a +// user-provided TraceWriter. Every RocksDB operation is written as a single +// trace. Each trace will have a timestamp and type, followed by the trace +// payload. +class BlockCacheTraceWriterImpl : public BlockCacheTraceWriter { + public: + BlockCacheTraceWriterImpl(SystemClock* clock, + const BlockCacheTraceWriterOptions& trace_options, + std::unique_ptr<TraceWriter>&& trace_writer); + ~BlockCacheTraceWriterImpl() = default; + // No copy and move. + BlockCacheTraceWriterImpl(const BlockCacheTraceWriterImpl&) = delete; + BlockCacheTraceWriterImpl& operator=(const BlockCacheTraceWriterImpl&) = + delete; + BlockCacheTraceWriterImpl(BlockCacheTraceWriterImpl&&) = delete; + BlockCacheTraceWriterImpl& operator=(BlockCacheTraceWriterImpl&&) = delete; + + // Pass Slice references to avoid copy. + Status WriteBlockAccess(const BlockCacheTraceRecord& record, + const Slice& block_key, const Slice& cf_name, + const Slice& referenced_key); + + // Write a trace header at the beginning, typically on initiating a trace, + // with some metadata like a magic number and RocksDB version. + Status WriteHeader(); + + private: + SystemClock* clock_; + BlockCacheTraceWriterOptions trace_options_; + std::unique_ptr<TraceWriter> trace_writer_; +}; + +// Write a trace record in human readable format, see +// https://github.com/facebook/rocksdb/wiki/Block-cache-analysis-and-simulation-tools#trace-format +// for details. +class BlockCacheHumanReadableTraceWriter { + public: + ~BlockCacheHumanReadableTraceWriter(); + + Status NewWritableFile(const std::string& human_readable_trace_file_path, + ROCKSDB_NAMESPACE::Env* env); + + Status WriteHumanReadableTraceRecord(const BlockCacheTraceRecord& access, + uint64_t block_id, uint64_t get_key_id); + + private: + char trace_record_buffer_[1024 * 1024]; + std::unique_ptr<ROCKSDB_NAMESPACE::WritableFile> + human_readable_trace_file_writer_; +}; + +// BlockCacheTraceReader helps read the trace file generated by +// BlockCacheTraceWriter using a user provided TraceReader. +class BlockCacheTraceReader { + public: + BlockCacheTraceReader(std::unique_ptr<TraceReader>&& reader); + virtual ~BlockCacheTraceReader() = default; + // No copy and move. + BlockCacheTraceReader(const BlockCacheTraceReader&) = delete; + BlockCacheTraceReader& operator=(const BlockCacheTraceReader&) = delete; + BlockCacheTraceReader(BlockCacheTraceReader&&) = delete; + BlockCacheTraceReader& operator=(BlockCacheTraceReader&&) = delete; + + Status ReadHeader(BlockCacheTraceHeader* header); + + Status ReadAccess(BlockCacheTraceRecord* record); + + private: + std::unique_ptr<TraceReader> trace_reader_; +}; + +// Read a trace record in human readable format, see +// https://github.com/facebook/rocksdb/wiki/Block-cache-analysis-and-simulation-tools#trace-format +// for detailed. +class BlockCacheHumanReadableTraceReader : public BlockCacheTraceReader { + public: + BlockCacheHumanReadableTraceReader(const std::string& trace_file_path); + + ~BlockCacheHumanReadableTraceReader(); + + Status ReadHeader(BlockCacheTraceHeader* header); + + Status ReadAccess(BlockCacheTraceRecord* record); + + private: + std::ifstream human_readable_trace_reader_; +}; + +// A block cache tracer. It downsamples the accesses according to +// trace_options and uses BlockCacheTraceWriter to write the access record to +// the trace file. +class BlockCacheTracer { + public: + BlockCacheTracer(); + ~BlockCacheTracer(); + // No copy and move. + BlockCacheTracer(const BlockCacheTracer&) = delete; + BlockCacheTracer& operator=(const BlockCacheTracer&) = delete; + BlockCacheTracer(BlockCacheTracer&&) = delete; + BlockCacheTracer& operator=(BlockCacheTracer&&) = delete; + + // Start writing block cache accesses to the trace_writer. + Status StartTrace(const BlockCacheTraceOptions& trace_options, + std::unique_ptr<BlockCacheTraceWriter>&& trace_writer); + + // Stop writing block cache accesses to the trace_writer. + void EndTrace(); + + bool is_tracing_enabled() const { + return writer_.load(std::memory_order_relaxed); + } + + Status WriteBlockAccess(const BlockCacheTraceRecord& record, + const Slice& block_key, const Slice& cf_name, + const Slice& referenced_key); + + // GetId cycles from 1 to std::numeric_limits<uint64_t>::max(). + uint64_t NextGetId(); + + private: + BlockCacheTraceOptions trace_options_; + // A mutex protects the writer_. + InstrumentedMutex trace_writer_mutex_; + std::atomic<BlockCacheTraceWriter*> writer_; + std::atomic<uint64_t> get_id_counter_; +}; + +} // namespace ROCKSDB_NAMESPACE |