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sdrangel/logging/logger.h
2017-11-18 20:07:53 +01:00

203 lines
6.6 KiB
C++

/**
@file
@author Stefan Frings
*/
#ifndef LOGGER_H
#define LOGGER_H
#include <QtGlobal>
#include <QThreadStorage>
#include <QHash>
#include <QStringList>
#include <QMutex>
#include <QObject>
#include "logglobal.h"
#include "logmessage.h"
namespace qtwebapp {
/**
Decorates and writes log messages to the console, stderr.
<p>
The decorator uses a predefined msgFormat string to enrich log messages
with additional information (e.g. timestamp).
<p>
The msgFormat string and also the message text may contain additional
variable names in the form <i>{name}</i> that are filled by values
taken from a static thread local dictionary.
<p>
The logger keeps a configurable number of messages in a ring-buffer.
A log message with a severity >= minLevel flushes the buffer,
so the stored messages get written out. If the buffer is disabled, then
only messages with severity >= minLevel are written out.
<p>
If you enable the buffer and use minLevel=2, then the application logs
only errors together with some buffered debug messages. But as long no
error occurs, nothing gets written out.
<p>
Each thread has it's own buffer.
<p>
The logger can be registered to handle messages from
the static global functions qDebug(), qWarning(), qCritical() and qFatal().
@see set() describes how to set logger variables
@see LogMessage for a description of the message decoration.
@warning You should prefer a derived class, for example FileLogger,
because logging to the console is less useful.
*/
class DECLSPEC Logger : public QObject {
Q_OBJECT
Q_DISABLE_COPY(Logger)
public:
/**
Constructor.
Uses the same defaults as the other constructor.
@param parent Parent object
*/
Logger(QObject* parent);
/**
Constructor.
@param msgFormat Format of the decoration, e.g. "{timestamp} {type} thread={thread}: {msg}"
@param timestampFormat Format of timestamp, e.g. "dd.MM.yyyy hh:mm:ss.zzz"
@param minLevel Minimum severity that genertes an output (0=debug, 1=warning, 2=critical, 3=fatal).
@param bufferSize Size of the backtrace buffer, number of messages per thread. 0=disabled.
@param parent Parent object
@see LogMessage for a description of the message decoration.
*/
Logger(const QString msgFormat="{timestamp} {type} {msg}", const QString timestampFormat="dd.MM.yyyy hh:mm:ss.zzz", const QtMsgType minLevel=QtDebugMsg, const int bufferSize=0, QObject* parent = 0);
/** Destructor */
virtual ~Logger();
/**
Decorate and log the message, if type>=minLevel.
This method is thread safe.
@param type Message type (level)
@param message Message text
@param file Name of the source file where the message was generated (usually filled with the macro __FILE__)
@param function Name of the function where the message was generated (usually filled with the macro __LINE__)
@param line Line Number of the source file, where the message was generated (usually filles with the macro __func__ or __FUNCTION__)
@see LogMessage for a description of the message decoration.
*/
virtual void log(const QtMsgType type, const QString& message, const QString &file="", const QString &function="", const int line=0);
/**
Installs this logger as the default message handler, so it
can be used through the global static logging functions (e.g. qDebug()).
*/
void installMsgHandler();
/**
* Sets the minimum message level on the fly
*/
void setMinMessageLevel(const QtMsgType& minMsgLevel) {
minLevel = minMsgLevel;
}
/**
* Get the current message level
*/
QtMsgType getMinMessageLevel() const {
return minLevel;
}
/**
Sets a thread-local variable that may be used to decorate log messages.
This method is thread safe.
@param name Name of the variable
@param value Value of the variable
*/
static void set(const QString& name, const QString& value);
/**
Clear the thread-local data of the current thread.
This method is thread safe.
@param buffer Whether to clear the backtrace buffer
@param variables Whether to clear the log variables
*/
virtual void clear(const bool buffer=true, const bool variables=true);
protected:
/** Format string for message decoration */
QString msgFormat;
/** Format string of timestamps */
QString timestampFormat;
/** Minimum level of message types that are written out */
QtMsgType minLevel;
/** Size of backtrace buffer, number of messages per thread. 0=disabled */
int bufferSize;
/** Used to synchronize access of concurrent threads */
static QMutex mutex;
/**
Decorate and write a log message to stderr. Override this method
to provide a different output medium.
*/
virtual void write(const LogMessage* logMessage);
private:
/** Pointer to the default logger, used by msgHandler() */
static Logger* defaultLogger;
/**
Message Handler for the global static logging functions (e.g. qDebug()).
Forward calls to the default logger.
<p>
In case of a fatal message, the program will abort.
Variables in the in the message are replaced by their values.
This method is thread safe.
@param type Message type (level)
@param message Message text
@param file Name of the source file where the message was generated (usually filled with the macro __FILE__)
@param function Name of the function where the message was generated (usually filled with the macro __LINE__)
@param line Line Number of the source file, where the message was generated (usually filles with the macro __func__ or __FUNCTION__)
*/
static void msgHandler(const QtMsgType type, const QString &message, const QString &file="", const QString &function="", const int line=0);
#if QT_VERSION >= 0x050000
/**
Wrapper for QT version 5.
@param type Message type (level)
@param context Message context
@param message Message text
@see msgHandler()
*/
static void msgHandler5(const QtMsgType type, const QMessageLogContext& context, const QString &message);
#else
/**
Wrapper for QT version 4.
@param type Message type (level)
@param message Message text
@see msgHandler()
*/
static void msgHandler4(const QtMsgType type, const char * message);
#endif
/** Thread local variables to be used in log messages */
static QThreadStorage<QHash<QString,QString>*> logVars;
/** Thread local backtrace buffers */
QThreadStorage<QList<LogMessage*>*> buffers;
};
} // end of namespace
#endif // LOGGER_H