src/main/include/log4cxx/mdc.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _LOG4CXX_MDC_H
#define _LOG4CXX_MDC_H

#if defined(_MSC_VER)
    #pragma warning (push)
    #pragma warning ( disable: 4231 4251 4275 4786 )
#endif

#include <log4cxx/log4cxx.h>
#include <log4cxx/logstring.h>
#include <map>

namespace log4cxx
{
/**
The MDC class is similar to the {@link log4cxx::NDC NDC} class except that it is
based on a map instead of a stack. It provides <em>mapped
diagnostic contexts</em>. A <em>Mapped Diagnostic Context</em>, 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.
*/
class LOG4CXX_EXPORT MDC
{
    public:
        /** String to string stl map.
        */
        typedef std::map<LogString, LogString> Map;

        /**
         *  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.
         *    @param key key
         *    @param value value.
         */
        MDC(const std::string& key, const std::string& value);
        ~MDC();

        /**
        * Put a context value (the <code>o</code> parameter) as identified
        * with the <code>key</code> parameter into the current thread's
        * context map.
        *
        * <p>If the current thread does not have a context map it is
        * created as a side effect.
         *    @param key key
         *    @param value value.
        */
        static void put(const std::string& key, const std::string& value);
        /**
        * Put a context value (the <code>o</code> parameter) as identified
        * with the <code>key</code> parameter into the current thread's
        * context map.
        *
        * <p>If the current thread does not have a context map it is
        * created as a side effect.
        * */
        static void putLS(const LogString& key, const LogString& value);

        /**
        * Get the context identified by the <code>key</code> parameter.
        *
        *  <p>This method has no side effects.
        *  @param key key.
        *  @return value for key, empty if not set.
        * */
        static std::string get(const std::string& key);
        /**
         *  Gets the context identified by the <code>key</code> parameter.
         *  @param key context key.
         *  @param dest destination to which value is appended.
         *  @return true if key has associated value.
         */
        static bool get(const LogString& key, LogString& dest);

        /**
        * Remove the the context identified by the <code>key</code>
        * parameter.
        *  @param key key.
        * @return value if key had been set, empty if not.
        */
        static std::string remove(const std::string& key);
#if LOG4CXX_WCHAR_T_API
        /**
         *  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.
         *    @param key key
         *    @param value value.
         */
        MDC(const std::wstring& key, const std::wstring& value);
        /**
        * Put a context value (the <code>o</code> parameter) as identified
        * with the <code>key</code> parameter into the current thread's
        * context map.
        *
        * <p>If the current thread does not have a context map it is
        * created as a side effect.
         *    @param key key
         *    @param value value.
        */
        static void put(const std::wstring& key, const std::wstring& value);
        /**
        * Get the context identified by the <code>key</code> parameter.
        *
        *  <p>This method has no side effects.
        *  @param key key.
        *  @return value for key, empty if not set.
        * */
        static std::wstring get(const std::wstring& key);
        /**
        * Remove the the context identified by the <code>key</code>
        * parameter.
        *  @param key key.
        * @return value if key had been set, empty if not.
        */
        static std::wstring remove(const std::wstring& key);
#endif
#if LOG4CXX_UNICHAR_API
        /**
         *  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.
         *    @param key key
         *    @param value value.
         */
        MDC(const std::basic_string<UniChar>& key, const std::basic_string<UniChar>& value);
        /**
        * Put a context value (the <code>o</code> parameter) as identified
        * with the <code>key</code> parameter into the current thread's
        * context map.
        *
        * <p>If the current thread does not have a context map it is
        * created as a side effect.
         *    @param key key
         *    @param value value.
        */
        static void put(const std::basic_string<UniChar>& key, const std::basic_string<UniChar>& value);
        /**
        * Get the context identified by the <code>key</code> parameter.
        *
        *  <p>This method has no side effects.
        *  @param key key.
        *  @return value for key, empty if not set.
        * */
        static std::basic_string<UniChar> get(const std::basic_string<UniChar>& key);
        /**
        * Remove the the context identified by the <code>key</code>
        * parameter.
        *  @param key key.
        * @return value if key had been set, empty if not.
        */
        static std::basic_string<UniChar> remove(const std::basic_string<UniChar>& key);
#endif
#if LOG4CXX_CFSTRING_API
        /**
         *  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.
         *    @param key key
         *    @param value value.
         */
        MDC(const CFStringRef& key, const CFStringRef& value);
        /**
        * Put a context value (the <code>o</code> parameter) as identified
        * with the <code>key</code> parameter into the current thread's
        * context map.
        *
        * <p>If the current thread does not have a context map it is
        * created as a side effect.
         *    @param key key
         *    @param value value.
        */
        static void put(const CFStringRef& key, const CFStringRef& value);
        /**
        * Get the context identified by the <code>key</code> parameter.
        *
        *  <p>This method has no side effects.
        *  @param key key.
        *  @return value for key, empty if not set.
        * */
        static CFStringRef get(const CFStringRef& key);
        /**
        * Remove the the context identified by the <code>key</code>
        * parameter.
        *  @param key key.
        * @return value if key had been set, empty if not.
        */
        static CFStringRef remove(const CFStringRef& key);
#endif
        /**
        * Remove the the context identified by the <code>key</code>
        * parameter.
        *  @param key key.
        * @param prevValue buffer to which previous value is appended.
        * @return true if key existed in MDC.
        */
        static bool remove(const LogString& key, LogString& prevValue);

        /**
        * Clear all entries in the MDC.
        */
        static void clear();

    private:
        MDC(const MDC&);
        MDC& operator=(const MDC&);
        LogString key;
}; // class MDC;
}  // namespace log4cxx

#if defined(_MSC_VER)
    #pragma warning (pop)
#endif


#endif // _LOG4CXX_MDC_H