xmlsocketappender.h

功能非常强的写日志程序

/*
 * Copyright 2003,2004 The Apache Software Foundation.
 * 
 * Licensed 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_NET_XML_SOCKET_APPENDER_H
#define _LOG4CXX_NET_XML_SOCKET_APPENDER_H
 
#include <log4cxx/appenderskeleton.h>
#include <log4cxx/helpers/socket.h>
#include <log4cxx/helpers/thread.h>

namespace log4cxx
{
	namespace helpers
	{
		class SocketOutputStream;
		typedef helpers::ObjectPtrT<SocketOutputStream> SocketOutputStreamPtr;
	} 

	namespace net
	{
		class XMLSocketAppender;
		typedef helpers::ObjectPtrT<XMLSocketAppender> XMLSocketAppenderPtr;

        /**
        Sends {@link spi::LoggingEvent LoggingEvent} objects in XML format
		to a remote a log server, usually a XMLSocketNode.

        <p>The XMLSocketAppender has the following properties:
		
        - If sent to a XMLSocketNode, remote logging
		is non-intrusive as far as the log event is concerned. In other
        words, the event will be logged with the same time stamp, {@link
        NDC NDC}, location info as if it were logged locally by
        the client.

        - XMLSocketAppenders use exclusively an XMLLayout. They ship an
        XML stream representing a {@link spi::LoggingEvent LoggingEvent} object
		to the server side.

       - Remote logging uses the TCP protocol. Consequently, if
        the server is reachable, then log events will eventually arrive
        at the server.

        - If the remote server is down, the logging requests are
        simply dropped. However, if and when the server comes back up,
        then event transmission is resumed transparently. This
        transparent reconneciton is performed by a <em>connector</em>
        thread which periodically attempts to connect to the server.

        - Logging events are automatically <em>buffered</em> by the
        native TCP implementation. This means that if the link to server
        is slow but still faster than the rate of (log) event production
        by the client, the client will not be affected by the slow
        network connection. However, if the network connection is slower
        then the rate of event production, then the client can only
        progress at the network rate. In particular, if the network link
        to the the server is down, the client will be blocked.
        @n @n On the other hand, if the network link is up, but the server
        is down, the client will not be blocked when making log requests
        but the log events will be lost due to server unavailability.

        - Even if an <code>XMLSocketAppender</code> is no longer
        attached to any logger, it will not be destroyed in
        the presence of a connector thread. A connector thread exists
        only if the connection to the server is down. To avoid this
        destruction problem, you should #close the the
        <code>XMLSocketAppender</code> explicitly. See also next item.
        @n @n Long lived applications which create/destroy many
        <code>XMLSocketAppender</code> instances should be aware of this
        destruction problem. Most other applications can safely
        ignore it.

        - If the application hosting the <code>XMLSocketAppender</code>
		exits before the <code>XMLSocketAppender</code> is closed either
        explicitly or subsequent to destruction, then there might
        be untransmitted data in the pipe which might be lost.
        @n @n To avoid lost data, it is usually sufficient to 
        #close the <code>XMLSocketAppender</code> either explicitly or by
        calling the LogManager#shutdown method
        before exiting the application.
       */
        
      	class LOG4CXX_EXPORT XMLSocketAppender : public AppenderSkeleton
    	{
		class Connector;
		friend class Connector;
    	public:
    		/**
    		The default port number of remote logging server (4560).
    		*/
    		static int DEFAULT_PORT;

    		/**
    		The default reconnection delay (30000 milliseconds or 30 seconds).
    		*/
    		static int DEFAULT_RECONNECTION_DELAY;

    	protected:
    		/**
    		host name
    		*/
    		String remoteHost;

    		/**
    		IP address
    		*/
    		helpers::InetAddress address;

    		int port;
    		helpers::SocketOutputStreamPtr os;
    		int reconnectionDelay;
    		bool locationInfo;
			char zeroBuffer[1024];

			/**
			An event XML stream cannot exceed 1024 bytes.
			*/
			static const int MAX_EVENT_LEN;

		public:
			DECLARE_LOG4CXX_OBJECT(XMLSocketAppender)
			BEGIN_LOG4CXX_CAST_MAP()
				LOG4CXX_CAST_ENTRY(XMLSocketAppender)
				LOG4CXX_CAST_ENTRY_CHAIN(AppenderSkeleton)
			END_LOG4CXX_CAST_MAP()

			XMLSocketAppender();
			~XMLSocketAppender();

    		/**
    		Connects to remote server at <code>address</code> and <code>port</code>.
    		*/
    		XMLSocketAppender(unsigned long address, int port);

    		/**
    		Connects to remote server at <code>host</code> and <code>port</code>.
    		*/
    		XMLSocketAppender(const String& host, int port);

    		/**
    		Connect to the specified <b>RemoteHost</b> and <b>Port</b>.
    		*/
    		void activateOptions();

		    /**
		    Set options
		    */
			virtual void setOption(const String& option, const String& value);
			
    		/**
    		* Close this appender.
    		*
    		* <p>This will mark the appender as closed and call then 
    		* #cleanUp method.
    		* */
    		void close();

    		/**
    		* Drop the connection to the remote host and release the underlying
    		* connector thread if it has been created
    		* */
    		void cleanUp();

    		void connect();


    		virtual void append(const spi::LoggingEventPtr& event);

    		/**
    		* The XMLSocketAppender use an internal XMLLayout. Hence, this method
    		* returns <code>false</code>.
    		* */
    		bool requiresLayout() const
    			{ return false; }

    		/**
    		* The <b>RemoteHost</b> option takes a string value which should be
    		* the host name of the server where an
			* XMLSocketNode is running.
    		* */
    		inline void setRemoteHost(const String& host)
    			{ address = helpers::InetAddress::getByName(host);
    			remoteHost = host; }

    		/**
    		Returns value of the <b>RemoteHost</b> option.
    		*/
    		inline const String& getRemoteHost() const
    			{ return remoteHost; }

    		/**
    		The <b>Port</b> option takes a positive integer representing
    		the port where the server is waiting for connections.
    		*/
    		void setPort(int port)
    			{ this->port = port; }

    		/**
    		Returns value of the <b>Port</b> option.
    		*/
    		int getPort() const
    			{ return port; }

    		/**
    		The <b>LocationInfo</b> option takes a boolean value. If true,
    		the information sent to the remote host will include location
    		information. By default no location information is sent to the server.
    		*/
    		void setLocationInfo(bool locationInfo)
    			{ this->locationInfo = locationInfo; }

    		/**
    		Returns value of the <b>LocationInfo</b> option.
    		*/
    		bool getLocationInfo() const
    			{ return locationInfo; }

    		/**
    		The <b>ReconnectionDelay</b> option takes a positive integer
    		representing the number of milliseconds to wait between each
    		failed connection attempt to the server. The default value of
    		this option is 30000 which corresponds to 30 seconds.

    		<p>Setting this option to zero turns off reconnection
    		capability.
    		*/
    		void setReconnectionDelay(int reconnectionDelay)
    			{ this->reconnectionDelay = reconnectionDelay; }

    		/**
    		Returns value of the <b>ReconnectionDelay</b> option.
    		*/
    		int getReconnectionDelay() const
    			{ return reconnectionDelay; }

		    void fireConnector();
       
       private:
		   /**
			The Connector will reconnect when the server becomes available
			again.  It does this by attempting to open a new connection every
			<code>reconnectionDelay</code> milliseconds.

			<p>It stops trying whenever a connection is established. It will
			restart to try reconnect to the server when previpously open
			connection is droppped.
			*/
			class LOG4CXX_EXPORT Connector : public helpers::Thread
			{
			public:
				bool interrupted;
				XMLSocketAppender * socketAppender;

				Connector(XMLSocketAppenderPtr socketAppender);
				virtual void run();
			}; // class Connector

			Connector * connector;
        }; // class XMLSocketAppender
    } // namespace net
}; // namespace log4cxx

#endif // _LOG4CXX_NET_XML_SOCKET_APPENDER_H