rocksdb/util/event_logger.h

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// Copyright (c) 2014, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#include <memory>
#include <sstream>
#include <string>
2015-03-13 18:29:32 +01:00
#include <chrono>
#include "rocksdb/env.h"
namespace rocksdb {
// JSONWritter doesn't support objects in arrays yet. There wasn't a need for
// that.
class JSONWritter {
public:
JSONWritter() : state_(kExpectKey), first_element_(true) { 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_ == kExpectKey);
state_ = kInArray;
if (!first_element_) {
stream_ << ", ";
}
stream_ << "[";
first_element_ = true;
}
void EndArray() {
assert(state_ == kInArray);
state_ = kExpectKey;
stream_ << "]";
first_element_ = false;
}
void StartObject() {
assert(state_ == kExpectValue);
stream_ << "{";
first_element_ = true;
}
void EndObject() {
assert(state_ == kExpectKey);
stream_ << "}";
first_element_ = false;
}
std::string Get() const { return stream_.str(); }
JSONWritter& operator<<(const char* val) {
if (state_ == kExpectKey) {
AddKey(val);
} else {
AddValue(val);
}
return *this;
}
JSONWritter& operator<<(const std::string& val) {
return *this << val.c_str();
}
template <typename T>
JSONWritter& operator<<(const T& val) {
assert(state_ != kExpectKey);
AddValue(val);
return *this;
}
private:
enum JSONWritterState {
kExpectKey,
kExpectValue,
kInArray,
};
JSONWritterState state_;
bool first_element_;
std::ostringstream stream_;
};
class EventLoggerStream {
public:
template <typename T>
EventLoggerStream& operator<<(const T& val) {
MakeStream();
*json_writter_ << val;
return *this;
}
~EventLoggerStream();
private:
void MakeStream() {
if (!json_writter_) {
json_writter_ = new JSONWritter();
*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);
Logger* logger_;
// ownership
JSONWritter* json_writter_;
};
// 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:
explicit EventLogger(Logger* logger) : logger_(logger) {}
EventLoggerStream Log() { return EventLoggerStream(logger_); }
private:
Logger* logger_;
};
} // namespace rocksdb