Logger.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
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// protected by copyright law and international copyright treaties.
//
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// agreements granting a non-assignable, non-transferable and non-exclusive license 
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// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or 
// reproduction of any part of this source code or associated reference material 
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// amendments to this copyright notice, are expressly prohibited.
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//

#pragma once

#include <OnixS/CME/MDH/Integral.h>
#include <OnixS/CME/MDH/String.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

/// Defines severity levels for log entries.
ONIXS_CMEMDH_LTWT_STRUCT LogSeverity
{
    /// Enumeration base. 
    typedef UInt32 Base;

    /// Log alternates.
    enum Enum 
    { 
        /// Only important information like 
        /// warnings and errors will be logged.
        /// 
        /// Mode is not suitable for further log 
        /// replays, because no market data is stored.
        Important = 10, 
                    
        /// Handler will log miscellaneous aspects 
        /// related with its execution like changes 
        /// in state, network data obtained, etc. All 
        /// critical important information like warnings 
        /// and errors will be logged as well. 
        /// 
        /// Most suitable mode to produce logs for further replay.
        Regular = 50, 
                    
        /// In addition to the data logged in 'Regular' 
        /// mode, Handler will output additional information
        /// like step-by-step changes into books, step-by-step
        /// processing of received network packets.
        Debug = 100
    };
};

/// Serializes log severity constant. 
ONIXS_CMEMDH_EXPORTED
void
toStr(
    std::string&,
    LogSeverity::Enum);

/// Serializes log severity constant. 
inline 
std::string
toStr(
    LogSeverity::Enum mode)
{
    std::string str;
    
    toStr(str, mode);
    
    return str;
}

/// Deserializes log severity constant. 
ONIXS_CMEMDH_EXPORTED
bool
fromStr(
    LogSeverity::Enum&,
    const Char*,
    size_t);

/// Categories for information being logged. 
ONIXS_CMEMDH_LTWT_STRUCT LogCategory
{
    // Enumeration base. 
    typedef UInt32 Base;

    /// Categories for information being logged.
    enum Enum
    {
        /// Log entry represents an error. 
        Error,

        /// Log entry represents a warning.
        Warning,

        /// Log entry represents informational message.
        Info,

        /// Log entry represents debug information. 
        Debug
    };
};

/// Serializes log category constant. 
ONIXS_CMEMDH_EXPORTED
void
toStr(
    std::string&,
    LogCategory::Enum);

/// Serializes log category constant. 
inline 
std::string
toStr(
    LogCategory::Enum mode)
{
    std::string str;
    
    toStr(str, mode);
    
    return str;
}

/// Deserializes log category constant. 
ONIXS_CMEMDH_EXPORTED
bool
fromStr(
    LogCategory::Enum&,
    const Char*,
    size_t);

/// Abstraction of log entry in logging services.
ONIXS_CMEMDH_EXPORTED_CLASS LogEntry
{
public:
    /// Specifies category of information being logged. 
    virtual void category(LogCategory::Enum) = 0;

    /// Specifies source of information being logged. 
    virtual void source(const StrRef&) = 0;

    /// Editable text to be a message of log entry.
    virtual std::string& message() = 0;

    /// Commits entry into a log and releases the instance. 
    ///
    /// Once given member is invoked, further invocation 
    /// of other members is not allowed as instance may be 
    /// disposed and thus do not exist anymore. 
    virtual void commit() = 0;

protected:
    /// Life-time is managed by Logger. 
    LogEntry()
    {
    }

    /// Life-time is managed by Logger. 
    ~LogEntry()
    {
    }

private:
    // Object copying is not supposed. 

    LogEntry(const LogEntry&);
    LogEntry& operator =(const LogEntry&);
};

/// Abstraction of logger. 
ONIXS_CMEMDH_EXPORTED_CLASS Logger
{
    // Object copying is not supposed. 

    Logger(const Logger&);
    Logger& operator =(const Logger&);

protected:
    /// Only descendants are to be created. 
    Logger()
    {
    }

    /// Only descendants are to be created. 
    ~Logger()
    {
    }

public:
    /// Adds entry to the log. 
    /// 
    /// Actual content can be added through the 
    /// interface of LogEntry and LogEvent classes.
    /// 
    /// @return Instance of LogEntry to build message 
    /// being added into the log or NULL if severity 
    /// of entry being added does not correspond to 
    /// logger's configuration. 
    virtual 
    LogEntry* 
    addEntry(
        LogSeverity::Enum) = 0;
};

ONIXS_CMEMDH_NAMESPACE_END