log.cpp

/*
 Copyright 2016 Nervana Systems Inc.
 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 <chrono>
#include <condition_variable>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <mutex>
#include <thread>

#include "log.hpp"

using namespace std;

namespace nervana
{
    class thread_starter;
}

string                    nervana::logger::log_path;
deque<string>             nervana::logger::queue;
static mutex              queue_mutex;
static condition_variable queue_condition;
static unique_ptr<thread> queue_thread;
static bool               active = false;

class nervana::thread_starter
{
public:
    thread_starter() { nervana::logger::start(); }
    virtual ~thread_starter() { nervana::logger::stop(); }
};

static nervana::thread_starter _starter;

void nervana::logger::set_log_path(const string& path)
{
    log_path = path;
}

void nervana::logger::start()
{
    active       = true;
    queue_thread = unique_ptr<thread>(new thread(&thread_entry, nullptr));
}

void nervana::logger::stop()
{
    {
        unique_lock<std::mutex> lk(queue_mutex);
        active = false;
        queue_condition.notify_one();
    }
    queue_thread->join();
}

void nervana::logger::process_event(const string& s)
{
    cout << s << "\n";
}

void nervana::logger::thread_entry(void* param)
{
    unique_lock<std::mutex> lk(queue_mutex);
    while (active)
    {
        queue_condition.wait(lk);
        while (!queue.empty())
        {
            process_event(queue.front());
            queue.pop_front();
        }
    }
}

void nervana::logger::log_item(const string& s)
{
    unique_lock<std::mutex> lk(queue_mutex);
    queue.push_back(s);
    queue_condition.notify_one();
}

nervana::log_helper::log_helper(LOG_TYPE type, const char* file, int line, const char* func)
{
    switch (type)
    {
    case LOG_TYPE::_LOG_TYPE_ERROR: _stream << "[ERR ] "; break;
    case LOG_TYPE::_LOG_TYPE_WARNING: _stream << "[WARN] "; break;
    case LOG_TYPE::_LOG_TYPE_INFO: _stream << "[INFO] "; break;
    }

    std::time_t tt = chrono::system_clock::to_time_t(chrono::system_clock::now());
    auto        tm = std::gmtime(&tt);
    char        buffer[256];
    //    strftime(buffer,sizeof(buffer), "%d/%b/%Y:%H:%M:%S %z", tm);
    //    strftime(buffer,sizeof(buffer), "%Y-%m-%d %H:%M:%S UTC", tm);
    strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M:%Sz", tm);
    _stream << buffer << " ";

    _stream << file;
    _stream << " " << line;
    //    _stream << " " << func;
    _stream << "\t";
}

nervana::log_helper::~log_helper()
{
    cout << _stream.str() << endl;
    // logger::log_item(_stream.str());
}