[89] | 1 | /*
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more
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| 3 | * contributor license agreements. See the NOTICE file distributed with
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| 4 | * this work for additional information regarding copyright ownership.
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| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0
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| 6 | * (the "License"); you may not use this file except in compliance with
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| 7 | * the License. You may obtain a copy of the License at
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| 8 | *
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| 9 | * http://www.apache.org/licenses/LICENSE-2.0
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| 10 | *
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| 11 | * Unless required by applicable law or agreed to in writing, software
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| 12 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 14 | * See the License for the specific language governing permissions and
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| 15 | * limitations under the License.
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| 16 | */
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| 17 |
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| 18 | #ifndef _LOG4CXX_HELPERS_CYCLICBUFFER_H
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| 19 | #define _LOG4CXX_HELPERS_CYCLICBUFFER_H
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| 20 |
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| 21 | #include <log4cxx/spi/loggingevent.h>
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| 22 |
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| 23 | namespace log4cxx
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| 24 | {
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| 25 | namespace helpers
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| 26 | {
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| 27 | /**
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| 28 | CyclicBuffer is used by other appenders to hold instances of
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| 29 | {@link log4cxx::spi::LoggingEvent LoggingEvent} for immediate
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| 30 | or deferred display.
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| 31 | <p>This buffer gives read access to any element in the buffer not
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| 32 | just the first or last element.
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| 33 | */
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| 34 | class LOG4CXX_EXPORT CyclicBuffer
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| 35 | {
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| 36 | log4cxx::spi::LoggingEventList ea;
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| 37 | int first;
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| 38 | int last;
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| 39 | int numElems;
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| 40 | int maxSize;
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| 41 |
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| 42 | public:
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| 43 | /**
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| 44 | Instantiate a new CyclicBuffer of at most <code>maxSize</code>
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| 45 | events.
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| 46 | The <code>maxSize</code> argument must a positive integer.
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| 47 | @param maxSize The maximum number of elements in the buffer.
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| 48 | @throws IllegalArgumentException if <code>maxSize</code>
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| 49 | is negative.
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| 50 | */
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| 51 | CyclicBuffer(int maxSize);
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| 52 | ~CyclicBuffer();
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| 53 |
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| 54 | /**
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| 55 | Add an <code>event</code> as the last event in the buffer.
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| 56 | */
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| 57 | void add(const spi::LoggingEventPtr& event);
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| 58 |
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| 59 | /**
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| 60 | Get the <i>i</i>th oldest event currently in the buffer. If
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| 61 | <em>i</em> is outside the range 0 to the number of elements
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| 62 | currently in the buffer, then <code>null</code> is returned.
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| 63 | */
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| 64 | spi::LoggingEventPtr get(int i);
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| 65 |
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| 66 | int getMaxSize() const
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| 67 | { return maxSize; }
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| 68 |
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| 69 | /**
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| 70 | Get the oldest (first) element in the buffer. The oldest element
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| 71 | is removed from the buffer.
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| 72 | */
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| 73 | spi::LoggingEventPtr get();
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| 74 |
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| 75 | /**
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| 76 | Get the number of elements in the buffer. This number is
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| 77 | guaranteed to be in the range 0 to <code>maxSize</code>
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| 78 | (inclusive).
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| 79 | */
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| 80 | int length() const
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| 81 | { return numElems; }
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| 82 |
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| 83 | /**
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| 84 | Resize the cyclic buffer to <code>newSize</code>.
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| 85 | @throws IllegalArgumentException if <code>newSize</code> is negative.
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| 86 | */
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| 87 | void resize(int newSize);
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| 88 | }; // class CyclicBuffer
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| 89 | } //namespace helpers
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| 90 | } //namespace log4cxx
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| 91 |
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| 92 | #endif //_LOG4CXX_HELPERS_CYCLICBUFFER_H
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