nesteddiagnosticcontext.h

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//
// NestedDiagnosticContext.h
//
// $Id: //poco/Main/Foundation/include/Foundation/NestedDiagnosticContext.h#5 $
//
// Definition of the NestedDiagnosticContext class.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef Foundation_NestedDiagnosticContext_INCLUDED
#define Foundation_NestedDiagnosticContext_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef STD_VECTOR_INCLUDED
#include <vector>
#define STD_VECTOR_INCLUDED
#endif
#ifndef STD_OSTREAM_INCLUDED
#include <ostream>
#define STD_OSTREAM_INCLUDED
#endif


Foundation_BEGIN


class NDCScope;


class Foundation_API NestedDiagnosticContext
	/// This class implements a Nested Diagnostic Context (NDC),
	/// as described in Neil Harrison's article "Patterns for Logging 
	/// Diagnostic Messages" in "Pattern Languages of Program Design 3"
	/// (Addison-Wesley).
	///
	/// A NDC maintains a stack of context information, consisting of
	/// an informational string (e.g., a method name), as well as an
	/// optional source code line number and file name.
	/// NDCs are especially useful for tagging log messages with
	/// context information which is very helpful in a multithreaded
	/// server scenario.
	/// Every thread has its own private NDC, which is automatically
	/// created when needed and destroyed when the thread terminates.
	///
	/// The NDCScope (or NDC::Scope) class can be used to automatically
	/// push information at the beginning of a scope, and to pop it
	/// at the end.
	/// The poco_ndc(info) macro augments the information with a
	/// source code line number and file name.
{
public:
	typedef NDCScope Scope;

	NestedDiagnosticContext();
		/// Creates the NestedDiagnosticContext.

	NestedDiagnosticContext(const NestedDiagnosticContext& ctx);
		/// Copy constructor.

	~NestedDiagnosticContext();
		/// Destroys the NestedDiagnosticContext.
		
	NestedDiagnosticContext& operator = (const NestedDiagnosticContext& ctx);
		/// Assignment operator.
		
	void push(const std::string& info);
		/// Pushes a context (without line number and filename) onto the stack.
		
	void push(const std::string& info, int line, const char* filename);
		/// Pushes a context (including line number and filename) 
		/// onto the stack. Filename must be a static string, such as the
		/// one produced by the __FILE__ preprocessor macro.

	void pop();
		/// Pops the top-most context off the stack.
		
	int depth() const;
		/// Returns the depth (number of contexts) of the stack.
	
	std::string toString() const;
		/// Returns the stack as a string with entries
		/// delimited by colons. The string does not contain
		/// line numbers and filenames.
		
	void dump(std::ostream& ostr) const;
		/// Dumps the stack (including line number and filenames)
		/// to the given stream. The entries are delimited by
		/// a newline.

	void dump(std::ostream& ostr, const std::string& delimiter) const;
		/// Dumps the stack (including line number and filenames)
		/// to the given stream.
		
	void clear();
		/// Clears the NDC stack.
	
	static NestedDiagnosticContext& current();
		/// Returns the current thread's NDC.

private:
	struct Context
	{
		std::string info;
		const char* file;
		int         line;
	};
	typedef std::vector<Context> Stack;
	
	Stack _stack;
};


typedef NestedDiagnosticContext NDC;


class Foundation_API NDCScope
	/// This class can be used to automatically push a context onto
	/// the NDC stack at the beginning of a scope, and to pop
	/// the context at the end of the scope.
{
public:
	NDCScope(const std::string& info);
		/// Pushes a context on the stack.
		
	NDCScope(const std::string& info, int line, const char* filename);
		/// Pushes a context on the stack.

	~NDCScope();
		/// Pops the top-most context off the stack.
};


//
// inlines
//
inline NDCScope::NDCScope(const std::string& info)
{
	NestedDiagnosticContext::current().push(info);
}

	
inline NDCScope::NDCScope(const std::string& info, int line, const char* filename)
{
	NestedDiagnosticContext::current().push(info, line, filename);
}


inline NDCScope::~NDCScope()
{
	NestedDiagnosticContext::current().pop();
}


//
// helper macros
//
#define poco_ndc(msg) \
	Foundation::NDCScope _theNdcScope(msg, __LINE__, __FILE__)


Foundation_END


#endif // Foundation_NestedDiagnosticContext_INCLUDED