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address chainbase uniqueness violation issues #44

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merged 1 commit into from
May 6, 2019
Merged

address chainbase uniqueness violation issues #44

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25 changes: 16 additions & 9 deletions include/chainbase/chainbase.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -220,11 +220,15 @@ namespace chainbase {
return *insert_result.first;
}

/**
* @pre modifier cannot change the object in such a way that causes a uniqueness violation for any unique indices
* @pre any modifications done within an undo session for a given generic_index must satisfy the condition that the compacted set of modifications in the session can be undone in any order without causing a uniqueness violation in any intermediate step
*/
template<typename Modifier>
void modify( const value_type& obj, Modifier&& m ) {
on_modify( obj );
auto ok = _indices.modify( _indices.iterator_to( obj ), m );
if( !ok ) BOOST_THROW_EXCEPTION( std::logic_error( "Could not modify object, most likely a uniqueness constraint was violated" ) );
if( !ok ) std::abort(); // uniqueness violation
}

void remove( const value_type& obj ) {
Expand Down Expand Up @@ -309,28 +313,31 @@ namespace chainbase {
/**
* Restores the state to how it was prior to the current session discarding all changes
* made between the last revision and the current revision.
*
* This function will not throw an exception but will abort if a uniqueness constraint violation
* is encountered while undoing, likely because of a prior violation of the preconditions of modify.
*/
void undo() {
if( !enabled() ) return;

const auto& head = _stack.back();

for( auto& item : head.old_values ) {
auto ok = _indices.modify( _indices.find( item.second.id ), [&]( value_type& v ) {
v = std::move( item.second );
});
if( !ok ) BOOST_THROW_EXCEPTION( std::logic_error( "Could not modify object, most likely a uniqueness constraint was violated" ) );
}

for( auto id : head.new_ids )
{
_indices.erase( _indices.find( id ) );
}
_next_id = head.old_next_id;

for( auto& item : head.old_values ) {
auto ok = _indices.modify( _indices.find( item.second.id ), [&]( value_type& v ) {
v = std::move( item.second );
});
if( !ok ) std::abort(); // uniqueness violation
}

for( auto& item : head.removed_values ) {
bool ok = _indices.emplace( std::move( item.second ) ).second;
if( !ok ) BOOST_THROW_EXCEPTION( std::logic_error( "Could not restore object, most likely a uniqueness constraint was violated" ) );
if( !ok ) std::abort(); // uniqueness violation
}

_stack.pop_back();
Expand Down