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arangodb/arangod/ReadCache/RevisionReader.cpp

103 lines
3.0 KiB
C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////
#include "RevisionReader.h"
#include "ReadCache/GlobalRevisionCacheChunk.h"
using namespace arangodb;
// constructor for a non-existing revision
RevisionReader::RevisionReader()
: _chunk(nullptr),
_offset(0),
_version(0),
_ownsReference(false),
_ownsReader(false) {}
// constructor for an existing revision
RevisionReader::RevisionReader(GlobalRevisionCacheChunk* chunk, RevisionOffset offset, RevisionVersion version)
: _chunk(chunk),
_offset(offset),
_version(version),
_ownsReference(true),
_ownsReader(true) {
TRI_ASSERT(_chunk != nullptr);
}
RevisionReader::~RevisionReader() {
if (_ownsReference) {
_chunk->removeReference();
}
if (_ownsReader) {
_chunk->removeReader();
}
}
// move constructor
RevisionReader::RevisionReader(RevisionReader&& other) noexcept
: _chunk(other._chunk),
_offset(other._offset),
_version(other._version),
_ownsReference(other._ownsReference),
_ownsReader(other._ownsReader) {
// other RevisionReader is not responsible for anything when we're done with it
other._chunk = nullptr;
other._ownsReference = false;
other._ownsReader = false;
}
RevisionReader& RevisionReader::operator=(RevisionReader&& other) noexcept {
if (this != &other) {
_chunk = other._chunk;
_offset = other._offset;
_version = other._version;
_ownsReference = other._ownsReference;
_ownsReader = other._ownsReader;
// other RevisionReader is not responsible for anything when we're done with it
other._chunk = nullptr;
other._ownsReference = false;
other._ownsReader = false;
}
return *this;
}
arangodb::velocypack::Slice RevisionReader::revision() const {
if (_chunk == nullptr) {
// non-existing revision
return arangodb::velocypack::Slice();
}
return arangodb::velocypack::Slice(_chunk->read(_offset.value + sizeof(uint64_t)));
}
uint64_t RevisionReader::collectionId() const {
if (_chunk == nullptr) {
// non-existing revision
return 0;
}
return *reinterpret_cast<uint64_t const*>(_chunk->read(_offset.value));
}