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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 <sstream>
#include <string>
#include <chrono>
#include "rocksdb/env.h"
#include "util/log_buffer.h"
namespace rocksdb {
class JSONWriter {
public:
JSONWriter() : state_(kExpectKey), first_element_(true), in_array_(false) {
stream_ << "{";
}
void AddKey(const std::string& key) {
assert(state_ == kExpectKey);
if (!first_element_) {
stream_ << ", ";
}
stream_ << "\"" << key << "\": ";
state_ = kExpectValue;
first_element_ = false;
}
void AddValue(const char* value) {
assert(state_ == kExpectValue || state_ == kInArray);
if (state_ == kInArray && !first_element_) {
stream_ << ", ";
}
stream_ << "\"" << value << "\"";
if (state_ != kInArray) {
state_ = kExpectKey;
}
first_element_ = false;
}
template <typename T>
void AddValue(const T& value) {
assert(state_ == kExpectValue || state_ == kInArray);
if (state_ == kInArray && !first_element_) {
stream_ << ", ";
}
stream_ << value;
if (state_ != kInArray) {
state_ = kExpectKey;
}
first_element_ = false;
}
void StartArray() {
assert(state_ == kExpectValue);
state_ = kInArray;
in_array_ = true;
stream_ << "[";
first_element_ = true;
}
void EndArray() {
assert(state_ == kInArray);
state_ = kExpectKey;
in_array_ = false;
stream_ << "]";
first_element_ = false;
}
void StartObject() {
assert(state_ == kExpectValue);
state_ = kExpectKey;
stream_ << "{";
first_element_ = true;
}
void EndObject() {
assert(state_ == kExpectKey);
stream_ << "}";
first_element_ = false;
}
void StartArrayedObject() {
assert(state_ == kInArray && in_array_);
state_ = kExpectValue;
if (!first_element_) {
stream_ << ", ";
}
StartObject();
}
void EndArrayedObject() {
assert(in_array_);
EndObject();
state_ = kInArray;
}
std::string Get() const { return stream_.str(); }
JSONWriter& operator<<(const char* val) {
if (state_ == kExpectKey) {
AddKey(val);
} else {
AddValue(val);
}
return *this;
}
JSONWriter& operator<<(const std::string& val) {
return *this << val.c_str();
}
template <typename T>
JSONWriter& operator<<(const T& val) {
assert(state_ != kExpectKey);
AddValue(val);
return *this;
}
private:
enum JSONWriterState {
kExpectKey,
kExpectValue,
kInArray,
kInArrayedObject,
};
JSONWriterState state_;
bool first_element_;
bool in_array_;
std::ostringstream stream_;
};
class EventLoggerStream {
public:
template <typename T>
EventLoggerStream& operator<<(const T& val) {
MakeStream();
*json_writer_ << val;
return *this;
}
void StartArray() { json_writer_->StartArray(); }
void EndArray() { json_writer_->EndArray(); }
void StartObject() { json_writer_->StartObject(); }
void EndObject() { json_writer_->EndObject(); }
~EventLoggerStream();
private:
void MakeStream() {
if (!json_writer_) {
json_writer_ = new JSONWriter();
*this << "time_micros"
<< std::chrono::duration_cast<std::chrono::microseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
}
}
friend class EventLogger;
explicit EventLoggerStream(Logger* logger);
explicit EventLoggerStream(LogBuffer* log_buffer);
// exactly one is non-nullptr
Logger* const logger_;
LogBuffer* const log_buffer_;
// ownership
JSONWriter* json_writer_;
};
// here is an example of the output that will show up in the LOG:
// 2015/01/15-14:13:25.788019 1105ef000 EVENT_LOG_v1 {"time_micros":
// 1421360005788015, "event": "table_file_creation", "file_number": 12,
// "file_size": 1909699}
class EventLogger {
public:
static const char* Prefix() {
return "EVENT_LOG_v1";
}
explicit EventLogger(Logger* logger) : logger_(logger) {}
EventLoggerStream Log() { return EventLoggerStream(logger_); }
EventLoggerStream LogToBuffer(LogBuffer* log_buffer) {
return EventLoggerStream(log_buffer);
}
void Log(const JSONWriter& jwriter);
static void Log(Logger* logger, const JSONWriter& jwriter);
static void LogToBuffer(LogBuffer* log_buffer, const JSONWriter& jwriter);
private:
Logger* logger_;
};
} // namespace rocksdb
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