rcpp_framework/web_backends/drogon/trantor/utils/AsyncFileLogger.cc

/**
 *
 *  AsyncFileLogger.cc
 *  An Tao
 *
 *  Public header file in trantor lib.
 *
 *  Copyright 2018, An Tao.  All rights reserved.
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the License file.
 *
 *
 */

#include <trantor/utils/AsyncFileLogger.h>
#ifndef _WIN32
#include <unistd.h>
#ifdef __linux__
#include <sys/prctl.h>
#endif
#endif
#include <string.h>
#include <chrono>
#include <functional>
#include <iostream>

namespace trantor {
static constexpr std::chrono::seconds kLogFlushTimeout{ 1 };
static constexpr size_t kMemBufferSize{ 4 * 1024 * 1024 };
extern const char *strerror_tl(int savedErrno);
} // namespace trantor

using namespace trantor;

AsyncFileLogger::AsyncFileLogger() :
		logBufferPtr_(new std::string), nextBufferPtr_(new std::string) {
	logBufferPtr_->reserve(kMemBufferSize);
	nextBufferPtr_->reserve(kMemBufferSize);
}

AsyncFileLogger::~AsyncFileLogger() {
	// std::cout << "~AsyncFileLogger" << std::endl;
	stopFlag_ = true;
	if (threadPtr_) {
		cond_.notify_all();
		threadPtr_->join();
	}
	// std::cout << "thread exit" << std::endl;
	{
		std::lock_guard<std::mutex> guard_(mutex_);
		if (logBufferPtr_->length() > 0) {
			writeBuffers_.push(logBufferPtr_);
		}
		while (!writeBuffers_.empty()) {
			StringPtr tmpPtr = (StringPtr &&) writeBuffers_.front();
			writeBuffers_.pop();
			writeLogToFile(tmpPtr);
		}
	}
}

void AsyncFileLogger::output(const char *msg, const uint64_t len) {
	std::lock_guard<std::mutex> guard_(mutex_);
	if (len > kMemBufferSize)
		return;
	if (!logBufferPtr_) {
		logBufferPtr_ = std::make_shared<std::string>();
		logBufferPtr_->reserve(kMemBufferSize);
	}
	if (logBufferPtr_->capacity() - logBufferPtr_->length() < len) {
		swapBuffer();
		cond_.notify_one();
	}
	if (writeBuffers_.size() > 25) // 100M bytes logs in buffer
	{
		++lostCounter_;
		return;
	}

	if (lostCounter_ > 0) {
		char logErr[128];
		auto strlen =
				snprintf(logErr,
						sizeof(logErr),
						"%llu log information is lost\n",
						static_cast<long long unsigned int>(lostCounter_));
		lostCounter_ = 0;
		logBufferPtr_->append(logErr, strlen);
	}
	logBufferPtr_->append(msg, len);
}

void AsyncFileLogger::flush() {
	std::lock_guard<std::mutex> guard_(mutex_);
	if (logBufferPtr_->length() > 0) {
		// std::cout<<"flush log buffer
		// len:"<<logBufferPtr_->length()<<std::endl;
		swapBuffer();
		cond_.notify_one();
	}
}

void AsyncFileLogger::writeLogToFile(const StringPtr buf) {
	if (!loggerFilePtr_) {
		loggerFilePtr_ = std::unique_ptr<LoggerFile>(
				new LoggerFile(filePath_, fileBaseName_, fileExtName_));
	}
	loggerFilePtr_->writeLog(buf);
	if (loggerFilePtr_->getLength() > sizeLimit_) {
		loggerFilePtr_.reset();
	}
}

void AsyncFileLogger::logThreadFunc() {
#ifdef __linux__
	prctl(PR_SET_NAME, "AsyncFileLogger");
#endif
	while (!stopFlag_) {
		{
			std::unique_lock<std::mutex> lock(mutex_);
			while (writeBuffers_.size() == 0 && !stopFlag_) {
				if (cond_.wait_for(lock, kLogFlushTimeout) ==
						std::cv_status::timeout) {
					if (logBufferPtr_->length() > 0) {
						swapBuffer();
					}
					break;
				}
			}
			tmpBuffers_.swap(writeBuffers_);
		}

		while (!tmpBuffers_.empty()) {
			StringPtr tmpPtr = (StringPtr &&) tmpBuffers_.front();
			tmpBuffers_.pop();
			writeLogToFile(tmpPtr);
			tmpPtr->clear();
			{
				std::unique_lock<std::mutex> lock(mutex_);
				nextBufferPtr_ = tmpPtr;
			}
		}
		if (loggerFilePtr_)
			loggerFilePtr_->flush();
	}
}

void AsyncFileLogger::startLogging() {
	threadPtr_ = std::unique_ptr<std::thread>(
			new std::thread(std::bind(&AsyncFileLogger::logThreadFunc, this)));
}

AsyncFileLogger::LoggerFile::LoggerFile(const std::string &filePath,
		const std::string &fileBaseName,
		const std::string &fileExtName) :
		creationDate_(Date::date()),
		filePath_(filePath),
		fileBaseName_(fileBaseName),
		fileExtName_(fileExtName) {
	fileFullName_ = filePath + fileBaseName + fileExtName;
#ifndef _MSC_VER
	fp_ = fopen(fileFullName_.c_str(), "a");
#else
	fp_ = _fsopen(fileFullName_.c_str(), "a+", _SH_DENYWR);
#endif
	if (fp_ == nullptr) {
		std::cout << strerror_tl(errno) << std::endl;
	}
}

uint64_t AsyncFileLogger::LoggerFile::fileSeq_{ 0 };
void AsyncFileLogger::LoggerFile::writeLog(const StringPtr buf) {
	if (fp_) {
		// std::cout<<"write "<<buf->length()<<" bytes to file"<<std::endl;
		fwrite(buf->c_str(), 1, buf->length(), fp_);
	}
}

void AsyncFileLogger::LoggerFile::flush() {
	if (fp_) {
		fflush(fp_);
	}
}

uint64_t AsyncFileLogger::LoggerFile::getLength() {
	if (fp_)
		return ftell(fp_);
	return 0;
}

AsyncFileLogger::LoggerFile::~LoggerFile() {
	if (fp_) {
		fclose(fp_);
		char seq[12];
		snprintf(seq,
				sizeof(seq),
				".%06llu",
				static_cast<long long unsigned int>(fileSeq_ % 1000000));
		++fileSeq_;
		std::string newName =
				filePath_ + fileBaseName_ + "." +
				creationDate_.toCustomedFormattedString("%y%m%d-%H%M%S") +
				std::string(seq) + fileExtName_;
		rename(fileFullName_.c_str(), newName.c_str());
	}
}

void AsyncFileLogger::swapBuffer() {
	writeBuffers_.push(logBufferPtr_);
	if (nextBufferPtr_) {
		logBufferPtr_ = nextBufferPtr_;
		nextBufferPtr_.reset();
		logBufferPtr_->clear();
	} else {
		logBufferPtr_ = std::make_shared<std::string>();
		logBufferPtr_->reserve(kMemBufferSize);
	}
}