CLogger.h

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/* Copyright (C) 2024 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 <fstream>
#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:
    class ScopedReplacement;
 
    enum ELogMethod
    {
        Normal,
        Error,
        Warning
    };
 
    CLogger(std::ostream& mainLog, std::ostream& interestingLog, const 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;
 
    // 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{0};
    int m_NumberOfErrors{0};
    int m_NumberOfWarnings{0};
 
    // Used for Render()
    struct RenderedMessage
    {
        ELogMethod method;
        double time;
        std::string message;
    };
    std::deque<RenderedMessage> m_RenderMessages;
 
    // The logger might be constructed too early to allow us to call timer_Time(),
    // so we'll fill in the initial value later
    double m_RenderLastEraseTime{-1.0};
 
    // Lock for all state modified by logging commands
    std::mutex m_Mutex;
};
 
/**
 * Replaces `g_Logger` for as long as it's in scope.
 */
class CLogger::ScopedReplacement
{
public:
    ScopedReplacement(std::ostream& mainLog, std::ostream& interestingLog, const bool useDebugPrintf);
 
    ScopedReplacement(const ScopedReplacement&) = delete;
    ScopedReplacement& operator=(const ScopedReplacement&) = delete;
    ScopedReplacement(ScopedReplacement&&) = delete;
    ScopedReplacement& operator=(ScopedReplacement&&) = delete;
    ~ScopedReplacement();
 
private:
    CLogger m_ThisLogger;
    CLogger* m_OldLogger;
};
 
/**
 * This is used in the engine to log the messages to the logfiles.
 */
class FileLogger
{
public:
    FileLogger();
private:
    std::ofstream m_MainLog;
    std::ofstream m_InterestingLog;
    CLogger::ScopedReplacement m_ScopedReplacement;
};
 
/**
 * Helper class for unit tests - captures all log output, and returns it as a
 * single string.
 */
class TestLogger
{
public:
    TestLogger();
 
    std::string GetOutput();
private:
    std::stringstream m_Stream;
    CLogger::ScopedReplacement m_ScopedReplacement;
};
 
/**
 * Helper class for unit tests - redirects all log output to stdout.
 */
class TestStdoutLogger
{
public:
    TestStdoutLogger();
private:
    CLogger::ScopedReplacement m_ScopedReplacement;
};
 
#endif