rocksdb/trace_replay/io_tracer.cc

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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).
#include "trace_replay/io_tracer.h"
#include <cinttypes>
#include <cstdio>
#include <cstdlib>
#include "db/db_impl/db_impl.h"
#include "db/dbformat.h"
#include "rocksdb/slice.h"
#include "rocksdb/system_clock.h"
#include "rocksdb/trace_reader_writer.h"
#include "util/coding.h"
#include "util/hash.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
IOTraceWriter::IOTraceWriter(const std::shared_ptr<SystemClock>& clock,
const TraceOptions& trace_options,
std::unique_ptr<TraceWriter>&& trace_writer)
: clock_(clock),
trace_options_(trace_options),
trace_writer_(std::move(trace_writer)) {}
Status IOTraceWriter::WriteIOOp(const IOTraceRecord& record) {
uint64_t trace_file_size = trace_writer_->GetFileSize();
if (trace_file_size > trace_options_.max_trace_file_size) {
return Status::OK();
}
Trace trace;
trace.ts = record.access_timestamp;
trace.type = record.trace_type;
PutFixed64(&trace.payload, record.io_op_data);
Slice file_operation(record.file_operation);
PutLengthPrefixedSlice(&trace.payload, file_operation);
PutFixed64(&trace.payload, record.latency);
Slice io_status(record.io_status);
PutLengthPrefixedSlice(&trace.payload, io_status);
Slice file_name(record.file_name);
PutLengthPrefixedSlice(&trace.payload, file_name);
// Each bit in io_op_data stores which corresponding info from IOTraceOp will
// be added in the trace. Foreg, if bit at position 1 is set then
// IOTraceOp::kIOLen (length) will be logged in the record (Since
// IOTraceOp::kIOLen = 1 in the enum). So find all the set positions in
// io_op_data one by one and, update corresponsing info in the trace record,
// unset that bit to find other set bits until io_op_data = 0.
/* Write remaining options based on io_op_data set by file operation */
int64_t io_op_data = static_cast<int64_t>(record.io_op_data);
while (io_op_data) {
// Find the rightmost set bit.
uint32_t set_pos = static_cast<uint32_t>(log2(io_op_data & -io_op_data));
switch (set_pos) {
case IOTraceOp::kIOFileSize:
PutFixed64(&trace.payload, record.file_size);
break;
case IOTraceOp::kIOLen:
PutFixed64(&trace.payload, record.len);
break;
case IOTraceOp::kIOOffset:
PutFixed64(&trace.payload, record.offset);
break;
default:
assert(false);
}
// unset the rightmost bit.
io_op_data &= (io_op_data - 1);
}
std::string encoded_trace;
TracerHelper::EncodeTrace(trace, &encoded_trace);
return trace_writer_->Write(encoded_trace);
}
Status IOTraceWriter::WriteHeader() {
Trace trace;
trace.ts = clock_->NowMicros();
trace.type = TraceType::kTraceBegin;
PutLengthPrefixedSlice(&trace.payload, kTraceMagic);
PutFixed32(&trace.payload, kMajorVersion);
PutFixed32(&trace.payload, kMinorVersion);
std::string encoded_trace;
TracerHelper::EncodeTrace(trace, &encoded_trace);
return trace_writer_->Write(encoded_trace);
}
IOTraceReader::IOTraceReader(std::unique_ptr<TraceReader>&& reader)
: trace_reader_(std::move(reader)) {}
Status IOTraceReader::ReadHeader(IOTraceHeader* header) {
assert(header != nullptr);
std::string encoded_trace;
Status s = trace_reader_->Read(&encoded_trace);
if (!s.ok()) {
return s;
}
Trace trace;
s = TracerHelper::DecodeTrace(encoded_trace, &trace);
if (!s.ok()) {
return s;
}
header->start_time = trace.ts;
Slice enc_slice = Slice(trace.payload);
Slice magic_number;
if (!GetLengthPrefixedSlice(&enc_slice, &magic_number)) {
return Status::Corruption(
"Corrupted header in the trace file: Failed to read the magic number.");
}
if (magic_number.ToString() != kTraceMagic) {
return Status::Corruption(
"Corrupted header in the trace file: Magic number does not match.");
}
if (!GetFixed32(&enc_slice, &header->rocksdb_major_version)) {
return Status::Corruption(
"Corrupted header in the trace file: Failed to read rocksdb major "
"version number.");
}
if (!GetFixed32(&enc_slice, &header->rocksdb_minor_version)) {
return Status::Corruption(
"Corrupted header in the trace file: Failed to read rocksdb minor "
"version number.");
}
// We should have retrieved all information in the header.
if (!enc_slice.empty()) {
return Status::Corruption(
"Corrupted header in the trace file: The length of header is too "
"long.");
}
return Status::OK();
}
Status IOTraceReader::ReadIOOp(IOTraceRecord* record) {
assert(record);
std::string encoded_trace;
Status s = trace_reader_->Read(&encoded_trace);
if (!s.ok()) {
return s;
}
Trace trace;
s = TracerHelper::DecodeTrace(encoded_trace, &trace);
if (!s.ok()) {
return s;
}
record->access_timestamp = trace.ts;
record->trace_type = trace.type;
Slice enc_slice = Slice(trace.payload);
if (!GetFixed64(&enc_slice, &record->io_op_data)) {
return Status::Incomplete(
"Incomplete access record: Failed to read trace data.");
}
Slice file_operation;
if (!GetLengthPrefixedSlice(&enc_slice, &file_operation)) {
return Status::Incomplete(
"Incomplete access record: Failed to read file operation.");
}
record->file_operation = file_operation.ToString();
if (!GetFixed64(&enc_slice, &record->latency)) {
return Status::Incomplete(
"Incomplete access record: Failed to read latency.");
}
Slice io_status;
if (!GetLengthPrefixedSlice(&enc_slice, &io_status)) {
return Status::Incomplete(
"Incomplete access record: Failed to read IO status.");
}
record->io_status = io_status.ToString();
Slice file_name;
if (!GetLengthPrefixedSlice(&enc_slice, &file_name)) {
return Status::Incomplete(
"Incomplete access record: Failed to read file name.");
}
record->file_name = file_name.ToString();
// Each bit in io_op_data stores which corresponding info from IOTraceOp will
// be added in the trace. Foreg, if bit at position 1 is set then
// IOTraceOp::kIOLen (length) will be logged in the record (Since
// IOTraceOp::kIOLen = 1 in the enum). So find all the set positions in
// io_op_data one by one and, update corresponsing info in the trace record,
// unset that bit to find other set bits until io_op_data = 0.
/* Read remaining options based on io_op_data set by file operation */
// Assuming 63 bits will be used at max.
int64_t io_op_data = static_cast<int64_t>(record->io_op_data);
while (io_op_data) {
// Find the rightmost set bit.
uint32_t set_pos = static_cast<uint32_t>(log2(io_op_data & -io_op_data));
switch (set_pos) {
case IOTraceOp::kIOFileSize:
if (!GetFixed64(&enc_slice, &record->file_size)) {
return Status::Incomplete(
"Incomplete access record: Failed to read file size.");
}
break;
case IOTraceOp::kIOLen:
if (!GetFixed64(&enc_slice, &record->len)) {
return Status::Incomplete(
"Incomplete access record: Failed to read length.");
}
break;
case IOTraceOp::kIOOffset:
if (!GetFixed64(&enc_slice, &record->offset)) {
return Status::Incomplete(
"Incomplete access record: Failed to read offset.");
}
break;
default:
assert(false);
}
// unset the rightmost bit.
io_op_data &= (io_op_data - 1);
}
return Status::OK();
}
IOTracer::IOTracer() : tracing_enabled(false) { writer_.store(nullptr); }
IOTracer::~IOTracer() { EndIOTrace(); }
Status IOTracer::StartIOTrace(const std::shared_ptr<SystemClock>& clock,
const TraceOptions& trace_options,
std::unique_ptr<TraceWriter>&& trace_writer) {
InstrumentedMutexLock lock_guard(&trace_writer_mutex_);
if (writer_.load()) {
return Status::Busy();
}
trace_options_ = trace_options;
writer_.store(
new IOTraceWriter(clock, trace_options, std::move(trace_writer)));
tracing_enabled = true;
return writer_.load()->WriteHeader();
}
void IOTracer::EndIOTrace() {
InstrumentedMutexLock lock_guard(&trace_writer_mutex_);
if (!writer_.load()) {
return;
}
delete writer_.load();
writer_.store(nullptr);
tracing_enabled = false;
}
// TODO: Return status and handle that in file_system_tracer.h
void IOTracer::WriteIOOp(const IOTraceRecord& record) {
if (!writer_.load()) {
return;
}
InstrumentedMutexLock lock_guard(&trace_writer_mutex_);
if (!writer_.load()) {
return;
}
writer_.load()->WriteIOOp(record).PermitUncheckedError();
}
} // namespace ROCKSDB_NAMESPACE