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Merge pull request #6489 from Icinga/feature/object-packer
Implement object packer for consistent hashing
This commit is contained in:
Michael Friedrich
GitHub
commit
b16d96d197
@ -57,6 +57,7 @@ set(base_SOURCES
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number.cpp number.hpp number-script.cpp
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object.cpp object.hpp object-script.cpp
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objectlock.cpp objectlock.hpp
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object-packer.cpp object-packer.hpp
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objecttype.cpp objecttype.hpp
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perfdatavalue.cpp perfdatavalue.hpp perfdatavalue-ti.hpp
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primitivetype.cpp primitivetype.hpp
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268
lib/base/object-packer.cpp
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268
lib/base/object-packer.cpp
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@ -0,0 +1,268 @@
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/******************************************************************************
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* Icinga 2 *
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* Copyright (C) 2012-2018 Icinga Development Team (https://www.icinga.com/) *
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* *
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* This program is free software; you can redistribute it and/or *
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* modify it under the terms of the GNU General Public License *
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* as published by the Free Software Foundation; either version 2 *
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* of the License, or (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the Free Software Foundation *
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. *
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******************************************************************************/
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#include "base/object-packer.hpp"
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#include "base/debug.hpp"
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#include "base/dictionary.hpp"
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#include "base/array.hpp"
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#include "base/objectlock.hpp"
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#include <algorithm>
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#include <climits>
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#include <cstdint>
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#include <utility>
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#include <vector>
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using namespace icinga;
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// Just for the sake of code readability
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typedef std::vector<char> StringBuilder;
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union EndiannessDetector
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{
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EndiannessDetector()
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{
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i = 1;
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}
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int i;
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char buf[sizeof(int)];
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};
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static const EndiannessDetector l_EndiannessDetector;
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// Assumption: The compiler will optimize (away) if/else statements using this.
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#define MACHINE_LITTLE_ENDIAN (l_EndiannessDetector.buf[0])
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static void PackAny(const Value& value, StringBuilder& builder);
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/**
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* std::swap() seems not to work
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*/
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static inline void SwapBytes(char& a, char& b)
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{
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char c = a;
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a = b;
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b = c;
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}
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#if CHAR_MIN != 0
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union CharU2SConverter
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{
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CharU2SConverter()
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{
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s = 0;
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}
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unsigned char u;
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signed char s;
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};
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#endif
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/**
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* Avoid implementation-defined overflows during unsigned to signed casts
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*/
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static inline char UIntToByte(unsigned i)
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{
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#if CHAR_MIN == 0
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return i;
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#else
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CharU2SConverter converter;
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converter.u = i;
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return converter.s;
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#endif
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}
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/**
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* Append the given int as big-endian 64-bit unsigned int
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*/
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static inline void PackUInt64BE(uint_least64_t i, StringBuilder& builder)
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{
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char buf[8] = {
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UIntToByte(i >> 56u),
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UIntToByte((i >> 48u) & 255u),
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UIntToByte((i >> 40u) & 255u),
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UIntToByte((i >> 32u) & 255u),
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UIntToByte((i >> 24u) & 255u),
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UIntToByte((i >> 16u) & 255u),
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UIntToByte((i >> 8u) & 255u),
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UIntToByte(i & 255u)
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};
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builder.insert(builder.end(), (char*)buf, (char*)buf + 8);
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}
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union Double2BytesConverter
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{
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Double2BytesConverter()
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{
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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buf[3] = 0;
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buf[4] = 0;
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buf[5] = 0;
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buf[6] = 0;
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buf[7] = 0;
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}
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double f;
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char buf[8];
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};
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/**
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* Append the given double as big-endian IEEE 754 binary64
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*/
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static inline void PackFloat64BE(double f, StringBuilder& builder)
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{
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Double2BytesConverter converter;
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converter.f = f;
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if (MACHINE_LITTLE_ENDIAN) {
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SwapBytes(converter.buf[0], converter.buf[7]);
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SwapBytes(converter.buf[1], converter.buf[6]);
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SwapBytes(converter.buf[2], converter.buf[5]);
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SwapBytes(converter.buf[3], converter.buf[4]);
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}
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builder.insert(builder.end(), (char*)converter.buf, (char*)converter.buf + 8);
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}
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/**
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* Append the given string's length (BE uint64) and the string itself
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*/
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static inline void PackString(const String& string, StringBuilder& builder)
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{
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PackUInt64BE(string.GetLength(), builder);
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builder.insert(builder.end(), string.Begin(), string.End());
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}
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/**
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* Append the given array
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*/
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static inline void PackArray(const Array::Ptr& arr, StringBuilder& builder)
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{
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ObjectLock olock(arr);
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builder.emplace_back(5);
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PackUInt64BE(arr->GetLength(), builder);
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for (const Value& value : arr) {
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PackAny(value, builder);
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}
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}
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/**
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* Append the given dictionary
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*/
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static inline void PackDictionary(const Dictionary::Ptr& dict, StringBuilder& builder)
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{
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ObjectLock olock(dict);
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builder.emplace_back(6);
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PackUInt64BE(dict->GetLength(), builder);
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for (const Dictionary::Pair& kv : dict) {
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PackString(kv.first, builder);
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PackAny(kv.second, builder);
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}
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}
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/**
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* Append any JSON-encodable value
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*/
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static void PackAny(const Value& value, StringBuilder& builder)
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{
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switch (value.GetType()) {
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case ValueString:
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builder.emplace_back(4);
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PackString(value.Get<String>(), builder);
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break;
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case ValueNumber:
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builder.emplace_back(3);
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PackFloat64BE(value.Get<double>(), builder);
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break;
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case ValueBoolean:
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builder.emplace_back(value.ToBool() ? 2 : 1);
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break;
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case ValueEmpty:
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builder.emplace_back(0);
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break;
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case ValueObject:
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{
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const Object::Ptr& obj = value.Get<Object::Ptr>();
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Dictionary::Ptr dict = dynamic_pointer_cast<Dictionary>(obj);
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if (dict) {
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PackDictionary(dict, builder);
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break;
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}
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Array::Ptr arr = dynamic_pointer_cast<Array>(obj);
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if (arr) {
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PackArray(arr, builder);
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break;
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}
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}
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builder.emplace_back(0);
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break;
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default:
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VERIFY(!"Invalid variant type.");
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}
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}
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/**
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* Pack any JSON-encodable value to a BSON-similar structure suitable for consistent hashing
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*
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* Spec:
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* null: 0x00
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* false: 0x01
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* true: 0x02
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* number: 0x03 (ieee754_binary64_bigendian)payload
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* string: 0x04 (uint64_bigendian)payload.length (char[])payload
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* array: 0x05 (uint64_bigendian)payload.length (any[])payload
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* object: 0x06 (uint64_bigendian)payload.length (keyvalue[])payload.sort()
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*
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* any: null|false|true|number|string|array|object
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* keyvalue: (uint64_bigendian)key.length (char[])key (any)value
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*
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* Assumptions:
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* - double is IEEE 754 binary64
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* - all int types (signed and unsigned) and all float types share the same endianness
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* - char is exactly 8 bits wide and one char is exactly one byte affected by the machine endianness
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* - all input strings, arrays and dictionaries are at most 2^64-1 long
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*
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* If not, this function will silently produce invalid results.
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*/
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String icinga::PackObject(const Value& value)
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{
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StringBuilder builder;
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PackAny(value, builder);
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String result;
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result.insert(result.End(), builder.begin(), builder.end());
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return std::move(result);
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}
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35
lib/base/object-packer.hpp
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35
lib/base/object-packer.hpp
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@ -0,0 +1,35 @@
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/******************************************************************************
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* Icinga 2 *
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* Copyright (C) 2012-2018 Icinga Development Team (https://www.icinga.com/) *
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* *
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* This program is free software; you can redistribute it and/or *
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* modify it under the terms of the GNU General Public License *
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* as published by the Free Software Foundation; either version 2 *
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* of the License, or (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the Free Software Foundation *
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. *
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******************************************************************************/
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#ifndef OBJECT_PACKER
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#define OBJECT_PACKER
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#include "base/i2-base.hpp"
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namespace icinga
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{
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class String;
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class Value;
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String PackObject(const Value& value);
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}
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#endif /* OBJECT_PACKER */
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