icinga2/lib/base/fifo.cpp

142 lines
3.4 KiB
C++

/******************************************************************************
* Icinga 2 *
* Copyright (C) 2012-2018 Icinga Development Team (https://www.icinga.com/) *
* *
* This program is free software; you can redistribute it and/or *
* modify it under the terms of the GNU General Public License *
* as published by the Free Software Foundation; either version 2 *
* of the License, or (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the Free Software Foundation *
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. *
******************************************************************************/
#include "base/fifo.hpp"
using namespace icinga;
/**
* Destructor for the FIFO class.
*/
FIFO::~FIFO()
{
free(m_Buffer);
}
/**
* Resizes the FIFO's buffer so that it is at least newSize bytes long.
*
* @param newSize The minimum new size of the FIFO buffer.
*/
void FIFO::ResizeBuffer(size_t newSize, bool decrease)
{
if (m_AllocSize >= newSize && !decrease)
return;
newSize = (newSize / FIFO::BlockSize + 1) * FIFO::BlockSize;
if (newSize == m_AllocSize)
return;
auto *newBuffer = static_cast<char *>(realloc(m_Buffer, newSize));
if (!newBuffer)
BOOST_THROW_EXCEPTION(std::bad_alloc());
m_Buffer = newBuffer;
m_AllocSize = newSize;
}
/**
* Optimizes memory usage of the FIFO buffer by reallocating
* and moving the buffer.
*/
void FIFO::Optimize()
{
if (m_Offset > m_DataSize / 10 && m_Offset - m_DataSize > 1024) {
std::memmove(m_Buffer, m_Buffer + m_Offset, m_DataSize);
m_Offset = 0;
if (m_DataSize > 0)
ResizeBuffer(m_DataSize, true);
return;
}
}
size_t FIFO::Peek(void *buffer, size_t count, bool allow_partial)
{
ASSERT(allow_partial);
if (count > m_DataSize)
count = m_DataSize;
if (buffer)
std::memcpy(buffer, m_Buffer + m_Offset, count);
return count;
}
/**
* Implements IOQueue::Read.
*/
size_t FIFO::Read(void *buffer, size_t count, bool allow_partial)
{
ASSERT(allow_partial);
if (count > m_DataSize)
count = m_DataSize;
if (buffer)
std::memcpy(buffer, m_Buffer + m_Offset, count);
m_DataSize -= count;
m_Offset += count;
Optimize();
return count;
}
/**
* Implements IOQueue::Write.
*/
void FIFO::Write(const void *buffer, size_t count)
{
ResizeBuffer(m_Offset + m_DataSize + count, false);
std::memcpy(m_Buffer + m_Offset + m_DataSize, buffer, count);
m_DataSize += count;
SignalDataAvailable();
}
void FIFO::Close()
{ }
bool FIFO::IsEof() const
{
return false;
}
size_t FIFO::GetAvailableBytes() const
{
return m_DataSize;
}
bool FIFO::SupportsWaiting() const
{
return true;
}
bool FIFO::IsDataAvailable() const
{
return m_DataSize > 0;
}