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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "databuffer.h"
#include <algorithm>
#include <cstdio>
namespace vespalib {
namespace {
size_t padbefore(size_t alignment, const char *buf) {
return (alignment - (size_t(buf) % alignment)) % alignment;
}
}
DataBuffer::DataBuffer(size_t len, size_t alignment, const Alloc & initial) noexcept
: _alignment(alignment),
_externalBuf(nullptr),
_bufstart(nullptr),
_bufend(nullptr),
_datapt(nullptr),
_freept(nullptr),
_buffer(initial.create(0))
{
assert(_alignment > 0);
if (len > 0) {
// avoid very small buffers for performance reasons:
size_t bufsize = std::max(256ul, roundUp2inN(len + (_alignment - 1)));
Alloc newBuf(initial.create(bufsize));
_bufstart = static_cast<char *>(newBuf.get());
_buffer.swap(newBuf);
_datapt = _bufstart + padbefore(alignment, _bufstart);
_freept = _datapt;
_bufend = _bufstart + bufsize;
assert(_bufstart != nullptr);
}
}
DataBuffer::~DataBuffer() = default;
void
DataBuffer::moveFreeToData(size_t len)
{
assert(getFreeLen() >= len);
_freept += len;
}
void
DataBuffer::moveDeadToData(size_t len)
{
assert(getDeadLen() >= len);
_datapt -= len;
if (_bufstart != _externalBuf) {
assert(getDeadLen() >= padbefore(_alignment, _bufstart)); // Do not move ahead of alignment.
}
}
void
DataBuffer::moveDataToFree(size_t len)
{
assert(getDataLen() >= len);
_freept -= len;
}
bool
DataBuffer::shrink(size_t newsize)
{
if (getBufSize() <= newsize || getDataLen() > newsize) {
return false;
}
char *newbuf = nullptr;
char *newdata = nullptr;
newsize += (_alignment - 1);
Alloc newBuf(_buffer.create(newsize));
if (newsize != 0) {
newbuf = static_cast<char *>(newBuf.get());
newdata = newbuf + padbefore(_alignment, newbuf);
if (getDataLen() > 0) {
memcpy(newdata, _datapt, getDataLen());
}
}
_buffer.swap(newBuf);
_bufstart = newbuf;
_freept = newdata + getDataLen();
_datapt = newdata;
_bufend = newbuf + newsize;
return true;
}
void
DataBuffer::pack(size_t needbytes)
{
needbytes += (_alignment - 1);
size_t dataLen = getDataLen();
if ((getDeadLen() + getFreeLen()) < needbytes ||
(getDeadLen() + getFreeLen()) * 4 < dataLen)
{
size_t bufsize = std::max(256ul, roundUp2inN(needbytes+dataLen));
Alloc newBuf(_buffer.create(bufsize));
char *newbuf = static_cast<char *>(newBuf.get());
char *newdata = newbuf + padbefore(_alignment, newbuf);
if (dataLen > 0) {
memcpy(newdata, _datapt, dataLen);
}
_bufstart = newbuf;
_datapt = newdata;
_freept = newdata + dataLen;
_bufend = newbuf + bufsize;
_buffer.swap(newBuf);
} else {
char *datapt = _bufstart + padbefore(_alignment, _bufstart);
if (dataLen > 0) {
memmove(datapt, _datapt, dataLen);
}
_datapt = datapt;
_freept = _datapt + dataLen;
}
}
bool
DataBuffer::equals(DataBuffer *other)
{
if (getDataLen() != other->getDataLen()) {
return false;
}
if (getDataLen() == 0) {
return true;
}
return memcmp(getData(), other->getData(), getDataLen()) == 0;
}
void
DataBuffer::hexDump()
{
char *pt = _datapt;
printf("*** DataBuffer HexDump BEGIN ***\n");
uint32_t i = 0;
while (pt < _freept) {
printf("%x ", (unsigned char) *pt++);
if ((++i % 16) == 0)
printf("\n");
}
if ((i % 16) != 0)
printf("\n");
printf("*** DataBuffer HexDump END ***\n");
}
void
DataBuffer::swap(DataBuffer &other)
{
_buffer.swap(other._buffer);
std::swap(_alignment, other._alignment);
std::swap(_externalBuf, other._externalBuf);
std::swap(_bufstart, other._bufstart);
std::swap(_bufend, other._bufend);
std::swap(_datapt, other._datapt);
std::swap(_freept, other._freept);
}
vespalib::alloc::Alloc
DataBuffer::stealBuffer() &&
{
assert( ! referencesExternalData() );
_externalBuf = nullptr;
_bufstart = nullptr;
_bufend = nullptr;
_datapt = nullptr;
_freept = nullptr;
return std::move(_buffer);
}
bool
DataBuffer::referencesExternalData() const {
return (_externalBuf == _bufstart) && (getBufSize() > 0);
}
} // namespace vespalib
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