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// 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 <memory>
#include <unordered_map>
#include <utility>
#include "rocksdb/env.h"
#include "rocksdb/options.h"
#include "rocksdb/trace_reader_writer.h"
namespace ROCKSDB_NAMESPACE {
// This file contains Tracer and Replayer classes that enable capturing and
// replaying RocksDB traces.
class ColumnFamilyHandle;
class ColumnFamilyData;
class DB;
class DBImpl;
class Slice;
class WriteBatch;
extern const std::string kTraceMagic;
const unsigned int kTraceTimestampSize = 8;
const unsigned int kTraceTypeSize = 1;
const unsigned int kTracePayloadLengthSize = 4;
const unsigned int kTraceMetadataSize =
kTraceTimestampSize + kTraceTypeSize + kTracePayloadLengthSize;
// Supported Trace types.
enum TraceType : char {
kTraceBegin = 1,
kTraceEnd = 2,
kTraceWrite = 3,
kTraceGet = 4,
kTraceIteratorSeek = 5,
kTraceIteratorSeekForPrev = 6,
// Block cache related types.
kBlockTraceIndexBlock = 7,
kBlockTraceFilterBlock = 8,
kBlockTraceDataBlock = 9,
kBlockTraceUncompressionDictBlock = 10,
kBlockTraceRangeDeletionBlock = 11,
// All trace types should be added before kTraceMax
kTraceMax,
};
// TODO: This should also be made part of public interface to help users build
// custom TracerReaders and TraceWriters.
//
// The data structure that defines a single trace.
struct Trace {
uint64_t ts; // timestamp
TraceType type;
std::string payload;
void reset() {
ts = 0;
type = kTraceMax;
payload.clear();
}
};
class TracerHelper {
public:
// Encode a trace object into the given string.
static void EncodeTrace(const Trace& trace, std::string* encoded_trace);
// Decode a string into the given trace object.
static Status DecodeTrace(const std::string& encoded_trace, Trace* trace);
};
// Tracer captures all RocksDB operations 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 Tracer {
public:
Tracer(Env* env, const TraceOptions& trace_options,
std::unique_ptr<TraceWriter>&& trace_writer);
~Tracer();
// Trace all write operations -- Put, Merge, Delete, SingleDelete, Write
Status Write(WriteBatch* write_batch);
// Trace Get operations.
Status Get(ColumnFamilyHandle* cfname, const Slice& key);
// Trace Iterators.
Status IteratorSeek(const uint32_t& cf_id, const Slice& key);
Status IteratorSeekForPrev(const uint32_t& cf_id, const Slice& key);
// Returns true if the trace is over the configured max trace file limit.
// False otherwise.
bool IsTraceFileOverMax();
// Writes a trace footer at the end of the tracing
Status Close();
private:
// Write a trace header at the beginning, typically on initiating a trace,
// with some metadata like a magic number, trace version, RocksDB version, and
// trace format.
Status WriteHeader();
// Write a trace footer, typically on ending a trace, with some metadata.
Status WriteFooter();
// Write a single trace using the provided TraceWriter to the underlying
// system, say, a filesystem or a streaming service.
Status WriteTrace(const Trace& trace);
// Helps in filtering and sampling of traces.
// Returns true if a trace should be skipped, false otherwise.
bool ShouldSkipTrace(const TraceType& type);
Env* env_;
TraceOptions trace_options_;
std::unique_ptr<TraceWriter> trace_writer_;
uint64_t trace_request_count_;
};
// Replayer helps to replay the captured RocksDB operations, using a user
// provided TraceReader.
// The Replayer is instantiated via db_bench today, on using "replay" benchmark.
class Replayer {
public:
Replayer(DB* db, const std::vector<ColumnFamilyHandle*>& handles,
std::unique_ptr<TraceReader>&& reader);
~Replayer();
// Replay all the traces from the provided trace stream, taking the delay
// between the traces into consideration.
Status Replay();
// Replay the provide trace stream, which is the same as Replay(), with
// multi-threads. Queries are scheduled in the thread pool job queue.
// User can set the number of threads in the thread pool.
Status MultiThreadReplay(uint32_t threads_num);
// Enables fast forwarding a replay by reducing the delay between the ingested
// traces.
// fast_forward : Rate of replay speedup.
// If 1, replay the operations at the same rate as in the trace stream.
// If > 1, speed up the replay by this amount.
Status SetFastForward(uint32_t fast_forward);
private:
Status ReadHeader(Trace* header);
Status ReadFooter(Trace* footer);
Status ReadTrace(Trace* trace);
// The background function for MultiThreadReplay to execute Get query
// based on the trace records.
static void BGWorkGet(void* arg);
// The background function for MultiThreadReplay to execute WriteBatch
// (Put, Delete, SingleDelete, DeleteRange) based on the trace records.
static void BGWorkWriteBatch(void* arg);
// The background function for MultiThreadReplay to execute Iterator (Seek)
// based on the trace records.
static void BGWorkIterSeek(void* arg);
// The background function for MultiThreadReplay to execute Iterator
// (SeekForPrev) based on the trace records.
static void BGWorkIterSeekForPrev(void* arg);
DBImpl* db_;
Env* env_;
std::unique_ptr<TraceReader> trace_reader_;
std::unordered_map<uint32_t, ColumnFamilyHandle*> cf_map_;
uint32_t fast_forward_;
};
// The passin arg of MultiThreadRepkay for each trace record.
struct ReplayerWorkerArg {
DB* db;
Trace trace_entry;
std::unordered_map<uint32_t, ColumnFamilyHandle*>* cf_map;
WriteOptions woptions;
ReadOptions roptions;
};
} // namespace ROCKSDB_NAMESPACE
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