CLogger.h

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/* Copyright (C) 2022 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_CLOGGER
#define INCLUDED_CLOGGER

#include <deque>
#include <fmt/printf.h>
#include <mutex>
#include <string>
#include <sstream>

class CCanvas2D;

class CLogger;
extern CLogger* g_Logger;


#define LOGMESSAGE(...)       g_Logger->WriteMessage(fmt::sprintf(__VA_ARGS__).c_str(), false)
#define LOGMESSAGERENDER(...) g_Logger->WriteMessage(fmt::sprintf(__VA_ARGS__).c_str(), true)
#define LOGWARNING(...)       g_Logger->WriteWarning(fmt::sprintf(__VA_ARGS__).c_str())
#define LOGERROR(...)         g_Logger->WriteError  (fmt::sprintf(__VA_ARGS__).c_str())

/**
 * Error/warning/message logging class.
 *
 * Thread-safety:
 * - Expected to be constructed/destructed in the main thread.
 * - The message logging functions may be called from any thread
 *   while the object is alive.
 */
class CLogger
{
    NONCOPYABLE(CLogger);
public:
    enum ELogMethod
    {
        Normal,
        Error,
        Warning
    };

    // Default constructor - outputs to normal log files
    CLogger();

    // Special constructor (mostly for testing) - outputs to provided streams.
    // Can take ownership of streams and delete them in the destructor.
    CLogger(std::ostream* mainLog, std::ostream* interestingLog, bool takeOwnership, bool useDebugPrintf);

    ~CLogger();

    // Functions to write different message types (Errors and warnings are placed
    // both in mainLog and intrestingLog.)
    void WriteMessage(const char* message, bool doRender);
    void WriteError  (const char* message);
    void WriteWarning(const char* message);

    // Render recent log messages onto the screen
    void Render(CCanvas2D& canvas);

private:
    void Init();

    void PushRenderMessage(ELogMethod method, const char* message);

    // Delete old timed-out entries from the list of text to render
    void CleanupRenderQueue();

    // the output streams
    std::ostream* m_MainLog;
    std::ostream* m_InterestingLog;
    bool m_OwnsStreams;

    // whether errors should be reported via debug_printf (default)
    // or suppressed (for tests that intentionally trigger errors)
    bool m_UseDebugPrintf;

    // vars to hold message counts
    int m_NumberOfMessages;
    int m_NumberOfErrors;
    int m_NumberOfWarnings;

    // Used for Render()
    struct RenderedMessage
    {
        ELogMethod method;
        double time;
        std::string message;
    };
    std::deque<RenderedMessage> m_RenderMessages;
    double m_RenderLastEraseTime;

    // Lock for all state modified by logging commands
    std::mutex m_Mutex;
};

/**
 * Helper class for unit tests - captures all log output while it is in scope,
 * and returns it as a single string.
 */
class TestLogger
{
    NONCOPYABLE(TestLogger);
public:
    TestLogger();
    ~TestLogger();
    std::string GetOutput();
private:
    CLogger* m_OldLogger;
    std::stringstream m_Stream;
};

/**
 * Helper class for unit tests - redirects all log output to stdout.
 */
class TestStdoutLogger
{
    NONCOPYABLE(TestStdoutLogger);
public:
    TestStdoutLogger();
    ~TestStdoutLogger();
private:
    CLogger* m_OldLogger;
};

#endif