log4cxx::MDC Class Reference

A Mapped Diagnostic Context, or MDC in short, is an instrument for distinguishing interleaved log output from different sources. More...

#include <mdc.h>

Public Types
typedef std::map< LogString, LogString >	Map
	String to string stl map.

Public Member Functions
	MDC (const std::string &key, const std::string &value)
	Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.
	~MDC ()
	MDC (const std::wstring &key, const std::wstring &value)
	Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.
	MDC (const std::basic_string< UniChar > &key, const std::basic_string< UniChar > &value)
	Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.
	MDC (const CFStringRef &key, const CFStringRef &value)
	Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.

Static Public Member Functions
static void	put (const std::string &key, const std::string &value)
	Set the key context in the current thread's context map to value.
static void	putLS (const LogString &key, const LogString &value)
	Set the key context in the current thread's context map to value.
static std::string	get (const std::string &key)
	Get the context identified by the key parameter.
static bool	get (const LogString &key, LogString &dest)
	Gets the context identified by the key parameter.
static std::string	remove (const std::string &key)
	Remove the the context identified by the key parameter.
static void	put (const std::wstring &key, const std::wstring &value)
	Set the key context in the current thread's context map to value.
static std::wstring	get (const std::wstring &key)
	Get the context identified by the key parameter.
static std::wstring	remove (const std::wstring &key)
	Remove the the context identified by the key parameter.
static void	put (const std::basic_string< UniChar > &key, const std::basic_string< UniChar > &value)
	Set the key context in the current thread's context map to value.
static std::basic_string< UniChar >	get (const std::basic_string< UniChar > &key)
	Get the context identified by the key parameter.
static std::basic_string< UniChar >	remove (const std::basic_string< UniChar > &key)
	Remove the the context identified by the key parameter.
static void	put (const CFStringRef &key, const CFStringRef &value)
	Set the key context in the current thread's context map to value.
static CFStringRef	get (const CFStringRef &key)
	Get the context identified by the key parameter.
static CFStringRef	remove (const CFStringRef &key)
	Remove the the context identified by the key parameter.
static bool	remove (const LogString &key, LogString &prevValue)
	Remove the the context identified by the key parameter.
static void	clear ()
	Clear all entries in the MDC.

Detailed Description

A Mapped Diagnostic Context, or MDC in short, is an instrument for distinguishing interleaved log output from different sources.

Log output is typically interleaved when a server handles multiple clients near-simultaneously.

MDC provides a constructor and destructor which simply call the put and remove methods, allowing for automatic cleanup when the current scope ends.

MDC operations such as put, remove and clear affect only logging events emitted in the calling thread. The contexts of other threads are not changed. That is, contexts are managed on a per thread basis.

The MDC class is similar to the NDC class except that it is based on a map instead of a stack.

Member Typedef Documentation

Map

typedef std::map<LogString, LogString> log4cxx::MDC::Map

String to string stl map.

Constructor & Destructor Documentation

MDC() [1/4]

log4cxx::MDC::MDC	(	const std::string &	key,
		const std::string &	value
	)

Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.

Both construction and destruction are expected to be on the same thread.

Parameters

key	context identifier
value	a string that distinguishes this context.

~MDC()

log4cxx::MDC::~MDC

(

)

MDC() [2/4]

log4cxx::MDC::MDC	(	const std::wstring &	key,
		const std::wstring &	value
	)

Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.

Both construction and destruction are expected to be on the same thread.

Parameters

key	context identifier
value	a string that distinguishes this context.

MDC() [3/4]

log4cxx::MDC::MDC	(	const std::basic_string< UniChar > &	key,
		const std::basic_string< UniChar > &	value
	)

Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.

Both construction and destruction are expected to be on the same thread.

Parameters

key	context identifier
value	a string that distinguishes this context.

MDC() [4/4]

log4cxx::MDC::MDC	(	const CFStringRef &	key,
		const CFStringRef &	value
	)

Places a key/value pair in the MDC for the current thread which will be removed during the corresponding destructor.

Both construction and destruction are expected to be on the same thread.

Parameters

key	context identifier
value	a string that distinguishes this context.

Member Function Documentation

clear()

static void log4cxx::MDC::clear ( )

static

Clear all entries in the MDC.

A thread that adds to the diagnostic context by calling put should call this method before exiting to prevent unbounded memory usage.

get() [1/5]

static CFStringRef log4cxx::MDC::get ( const CFStringRef &  key )

static

Get the context identified by the key parameter.

This method has no side effects.

Parameters

key	context identifier.

Returns

value for key, empty if not set.

get() [2/5]

static bool log4cxx::MDC::get ( const LogString &  key, LogString &  dest  )

static

Gets the context identified by the key parameter.

Parameters

key	context key.
dest	destination to which value is appended.

Returns

true if key has associated value.

get() [3/5]

static std::basic_string< UniChar > log4cxx::MDC::get ( const std::basic_string< UniChar > &  key )

static

Get the context identified by the key parameter.

This method has no side effects.

Parameters

key	context identifier.

Returns

value for key, empty if not set.

get() [4/5]

static std::string log4cxx::MDC::get ( const std::string &  key )

static

Get the context identified by the key parameter.

This method has no side effects.

Parameters

key	context identifier.

Returns

value for key, empty if not set.

get() [5/5]

static std::wstring log4cxx::MDC::get ( const std::wstring &  key )

static

Get the context identified by the key parameter.

This method has no side effects.

Parameters

key	context identifier.

Returns

value for key, empty if not set.

put() [1/4]

static void log4cxx::MDC::put ( const CFStringRef &  key, const CFStringRef &  value  )

static

Set the key context in the current thread's context map to value.

If the current thread does not have a context map it is created as a side effect.

Parameters

key	context identifier
value	a string that distinguishes this context.

put() [2/4]

static void log4cxx::MDC::put ( const std::basic_string< UniChar > &  key, const std::basic_string< UniChar > &  value  )

static

Set the key context in the current thread's context map to value.

If the current thread does not have a context map it is created as a side effect.

Parameters

key	context identifier
value	the value.

put() [3/4]

static void log4cxx::MDC::put ( const std::string &  key, const std::string &  value  )

static

Set the key context in the current thread's context map to value.

If the current thread does not have a context map it is created as a side effect.

Parameters

key	context identifier
value	a string that distinguishes this context.

put() [4/4]

static void log4cxx::MDC::put ( const std::wstring &  key, const std::wstring &  value  )

static

Set the key context in the current thread's context map to value.

If the current thread does not have a context map it is created as a side effect.

Parameters

key	context identifier
value	a string that distinguishes this context.

putLS()

static void log4cxx::MDC::putLS ( const LogString &  key, const LogString &  value  )

static

Set the key context in the current thread's context map to value.

If the current thread does not have a context map it is created as a side effect.

remove() [1/5]

static CFStringRef log4cxx::MDC::remove ( const CFStringRef &  key )

static

Remove the the context identified by the key parameter.

Parameters

key	context identifier.

Returns

value if key had been set, empty if not.

remove() [2/5]

static bool log4cxx::MDC::remove ( const LogString &  key, LogString &  prevValue  )

static

Remove the the context identified by the key parameter.

Parameters

key	context identifier.
prevValue	buffer to which previous value is appended.

Returns

true if key existed in MDC.

remove() [3/5]

static std::basic_string< UniChar > log4cxx::MDC::remove ( const std::basic_string< UniChar > &  key )

static

Remove the the context identified by the key parameter.

Parameters

key	context identifier.

Returns

value if key had been set, empty if not.

remove() [4/5]

static std::string log4cxx::MDC::remove ( const std::string &  key )

static

Remove the the context identified by the key parameter.

Parameters

key	context identifier.

Returns

value if key had been set, empty if not.

remove() [5/5]

static std::wstring log4cxx::MDC::remove ( const std::wstring &  key )

static

Remove the the context identified by the key parameter.

Parameters

key	context identifier.

Returns

value if key had been set, empty if not.

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The documentation for this class was generated from the following file:

• mdc.h