peerplays_migrated/libraries/db/include/graphene/db/flat_index.hpp

118 lines
4.9 KiB
C++

/*
* Copyright (c) 2015, Cryptonomex, Inc.
* All rights reserved.
*
* This source code is provided for evaluation in private test networks only, until September 8, 2015. After this date, this license expires and
* the code may not be used, modified or distributed for any purpose. Redistribution and use in source and binary forms, with or without modification,
* are permitted until September 8, 2015, provided that the following conditions are met:
*
* 1. The code and/or derivative works are used only for private test networks consisting of no more than 10 P2P nodes.
*
* 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 HOLDER 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.
*/
#pragma once
#include <graphene/db/index.hpp>
namespace graphene { namespace db {
/**
* @class flat_index
* @brief A flat index uses a vector<T> to store data
*
* This index is preferred in situations where the data will never be
* removed from main memory and when lots of small objects that
* are accessed in order are required.
*/
template<typename T>
class flat_index : public index
{
public:
typedef T object_type;
virtual const object& create( const std::function<void(object&)>& constructor ) override
{
auto id = get_next_id();
auto instance = id.instance();
if( instance >= _objects.size() ) _objects.resize( instance + 1 );
_objects[instance].id = id;
constructor( _objects[instance] );
use_next_id();
return _objects[instance];
}
virtual void modify( const object& obj, const std::function<void(object&)>& modify_callback ) override
{
assert( obj.id.instance() < _objects.size() );
modify_callback( _objects[obj.id.instance()] );
}
virtual const object& insert( object&& obj )override
{
auto instance = obj.id.instance();
assert( nullptr != dynamic_cast<T*>(&obj) );
if( _objects.size() <= instance ) _objects.resize( instance+1 );
_objects[instance] = std::move( static_cast<T&>(obj) );
return _objects[instance];
}
virtual void remove( const object& obj ) override
{
assert( nullptr != dynamic_cast<const T*>(&obj) );
const auto instance = obj.id.instance();
_objects[instance] = T();
}
virtual const object* find( object_id_type id )const override
{
assert( id.space() == T::space_id );
assert( id.type() == T::type_id );
const auto instance = id.instance();
if( instance >= _objects.size() ) return nullptr;
return &_objects[instance];
}
virtual void inspect_all_objects(std::function<void (const object&)> inspector)const override
{
try {
for( const auto& ptr : _objects )
{
inspector(ptr);
}
} FC_CAPTURE_AND_RETHROW()
}
class const_iterator
{
public:
const_iterator(){}
const_iterator( const typename vector<T>::const_iterator& a ):_itr(a){}
friend bool operator==( const const_iterator& a, const const_iterator& b ) { return a._itr == b._itr; }
friend bool operator!=( const const_iterator& a, const const_iterator& b ) { return a._itr != b._itr; }
const T* operator*()const { return static_cast<const T*>(&*_itr); }
const_iterator& operator++(int){ ++_itr; return *this; }
const_iterator& operator++() { ++_itr; return *this; }
private:
typename vector<T>::const_iterator _itr;
};
const_iterator begin()const { return const_iterator(_objects.begin()); }
const_iterator end()const { return const_iterator(_objects.end()); }
size_t size()const{ return _objects.size(); }
void resize( uint32_t s ) {
_objects.resize(s);
for( uint32_t i = 0; i < s; ++i )
_objects[i].id = object_id_type(object_type::space_id,object_type::type_id,i);
}
private:
vector< T > _objects;
};
} } // graphene::db