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LogEventInfoBuffer.cs
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LogEventInfoBuffer.cs
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//
// Copyright (c) 2004-2019 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * 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.
//
// * Neither the name of Jaroslaw Kowalski nor the names of its
// contributors may be used to endorse or promote products derived from this
// software without specific prior written permission.
//
// 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.
//
namespace NLog.Common
{
using System;
/// <summary>
/// A cyclic buffer of <see cref="LogEventInfo"/> object.
/// </summary>
public class LogEventInfoBuffer
{
private readonly object _lockObject = new object();
private readonly bool _growAsNeeded;
private readonly int _growLimit;
private AsyncLogEventInfo[] _buffer;
private int _getPointer;
private int _putPointer;
private int _count;
/// <summary>
/// Initializes a new instance of the <see cref="LogEventInfoBuffer" /> class.
/// </summary>
/// <param name="size">Buffer size.</param>
/// <param name="growAsNeeded">Whether buffer should grow as it becomes full.</param>
/// <param name="growLimit">The maximum number of items that the buffer can grow to.</param>
public LogEventInfoBuffer(int size, bool growAsNeeded, int growLimit)
{
_growAsNeeded = growAsNeeded;
_buffer = new AsyncLogEventInfo[size];
_growLimit = growLimit;
_getPointer = 0;
_putPointer = 0;
}
/// <summary>
/// Gets the capacity of the buffer
/// </summary>
public int Size => _buffer.Length;
/// <summary>
/// Gets the number of items in the buffer
/// </summary>
internal int Count { get { lock (_lockObject) return _count; } }
/// <summary>
/// Adds the specified log event to the buffer.
/// </summary>
/// <param name="eventInfo">Log event.</param>
/// <returns>The number of items in the buffer.</returns>
public int Append(AsyncLogEventInfo eventInfo)
{
lock (_lockObject)
{
// make room for additional item
if (_count >= _buffer.Length)
{
if (_growAsNeeded && _buffer.Length < _growLimit)
{
// create a new buffer, copy data from current
int newLength = _buffer.Length * 2;
if (newLength >= _growLimit)
{
newLength = _growLimit;
}
InternalLogger.Trace("Enlarging LogEventInfoBuffer from {0} to {1}", _buffer.Length, newLength);
var newBuffer = new AsyncLogEventInfo[newLength];
Array.Copy(_buffer, 0, newBuffer, 0, _buffer.Length);
_buffer = newBuffer;
}
else
{
// lose the oldest item
_getPointer = _getPointer + 1;
}
}
// put the item
_putPointer = _putPointer % _buffer.Length;
_buffer[_putPointer] = eventInfo;
_putPointer = _putPointer + 1;
_count++;
if (_count >= _buffer.Length)
{
_count = _buffer.Length;
}
return _count;
}
}
/// <summary>
/// Gets the array of events accumulated in the buffer and clears the buffer as one atomic operation.
/// </summary>
/// <returns>Events in the buffer.</returns>
public AsyncLogEventInfo[] GetEventsAndClear()
{
lock (_lockObject)
{
int cnt = _count;
if (cnt == 0)
return Internal.ArrayHelper.Empty<AsyncLogEventInfo>();
var returnValue = new AsyncLogEventInfo[cnt];
for (int i = 0; i < cnt; ++i)
{
int p = (_getPointer + i) % _buffer.Length;
var e = _buffer[p];
_buffer[p] = default(AsyncLogEventInfo); // we don't want memory leaks
returnValue[i] = e;
}
_count = 0;
_getPointer = 0;
_putPointer = 0;
return returnValue;
}
}
}
}