foundationdb/flow/JsonTraceLogFormatter.cpp

/*
 * JsonTraceLogFormatter.cpp
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2018 Apple Inc. and the FoundationDB project authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "flow/flow.h"
#include "flow/JsonTraceLogFormatter.h"

#include <sstream>

void JsonTraceLogFormatter::addref() {
	ReferenceCounted<JsonTraceLogFormatter>::addref();
}

void JsonTraceLogFormatter::delref() {
	ReferenceCounted<JsonTraceLogFormatter>::delref();
}

const char* JsonTraceLogFormatter::getExtension() {
	return "json";
}

const char* JsonTraceLogFormatter::getHeader() {
	return "";
}

const char* JsonTraceLogFormatter::getFooter() {
	return "";
}

namespace {

void escapeString(std::stringstream& ss, const std::string& source) {
	for (auto c : source) {
		if (c == '"') {
			ss << "\\\"";
		} else if (c == '\\') {
			ss << "\\\\";
		} else if (c == '\n') {
			ss << "\\n";
		} else if (c == '\r') {
			ss << "\\r";
		} else if (isprint(c)) {
			ss << c;
		} else {
			constexpr char hex[] = "0123456789abcdef";
			int x = int{ static_cast<uint8_t>(c) };
			ss << "\\x" << hex[x / 16] << hex[x % 16];
		}
	}
}

} // namespace

std::string JsonTraceLogFormatter::formatEvent(const TraceEventFields& fields) {
	std::stringstream ss;
	ss << "{  ";
	for (auto iter = fields.begin(); iter != fields.end(); ++iter) {
		if (iter != fields.begin()) {
			ss << ", ";
		}
		ss << "\"";
		escapeString(ss, iter->first);
		ss << "\": \"";
		escapeString(ss, iter->second);
		ss << "\"";
	}
	ss << " }\r\n";
	return ss.str();
}