| /* |
| * 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_HELPERS_CYCLICBUFFER_H |
| #define _LOG4CXX_HELPERS_CYCLICBUFFER_H |
| |
| #include <log4cxx/spi/loggingevent.h> |
| |
| namespace log4cxx |
| { |
| namespace helpers |
| { |
| /** |
| CyclicBuffer is used by other appenders to hold instances of |
| {@link log4cxx::spi::LoggingEvent LoggingEvent} for immediate |
| or deferred display. |
| <p>This buffer gives read access to any element in the buffer not |
| just the first or last element. |
| */ |
| class LOG4CXX_EXPORT CyclicBuffer |
| { |
| log4cxx::spi::LoggingEventList ea; |
| int first; |
| int last; |
| int numElems; |
| int maxSize; |
| |
| public: |
| /** |
| Instantiate a new CyclicBuffer of at most <code>maxSize</code> |
| events. |
| The <code>maxSize</code> argument must a positive integer. |
| @param maxSize The maximum number of elements in the buffer. |
| @throws IllegalArgumentException if <code>maxSize</code> |
| is negative. |
| */ |
| CyclicBuffer(int maxSize); |
| ~CyclicBuffer(); |
| |
| /** |
| Add an <code>event</code> as the last event in the buffer. |
| */ |
| void add(const spi::LoggingEventPtr& event); |
| |
| /** |
| Get the <i>i</i>th oldest event currently in the buffer. If |
| <em>i</em> is outside the range 0 to the number of elements |
| currently in the buffer, then <code>null</code> is returned. |
| */ |
| spi::LoggingEventPtr get(int i); |
| |
| int getMaxSize() const |
| { |
| return maxSize; |
| } |
| |
| /** |
| Get the oldest (first) element in the buffer. The oldest element |
| is removed from the buffer. |
| */ |
| spi::LoggingEventPtr get(); |
| |
| /** |
| Get the number of elements in the buffer. This number is |
| guaranteed to be in the range 0 to <code>maxSize</code> |
| (inclusive). |
| */ |
| int length() const |
| { |
| return numElems; |
| } |
| |
| /** |
| Resize the cyclic buffer to <code>newSize</code>. |
| @throws IllegalArgumentException if <code>newSize</code> is negative. |
| */ |
| void resize(int newSize); |
| }; // class CyclicBuffer |
| } //namespace helpers |
| } //namespace log4cxx |
| |
| #endif //_LOG4CXX_HELPERS_CYCLICBUFFER_H |