150 lines
4.9 KiB
C++
150 lines
4.9 KiB
C++
/*
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* Copyright (c) 2015 Cryptonomex, Inc., and contributors.
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*
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* The MIT License
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#pragma once
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#include <graphene/chain/database.hpp>
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/*
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* This file provides with() functions which modify the database
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* temporarily, then restore it. These functions are mostly internal
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* implementation detail of the database.
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*
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* Essentially, we want to be able to use "finally" to restore the
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* database regardless of whether an exception is thrown or not, but there
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* is no "finally" in C++. Instead, C++ requires us to create a struct
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* and put the finally block in a destructor. Aagh!
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*/
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namespace graphene { namespace chain { namespace detail {
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/**
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* Class used to help the with_skip_flags implementation.
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* It must be defined in this header because it must be
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* available to the with_skip_flags implementation,
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* which is a template and therefore must also be defined
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* in this header.
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*/
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struct skip_flags_restorer
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{
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skip_flags_restorer( node_property_object& npo, uint32_t old_skip_flags )
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: _npo( npo ), _old_skip_flags( old_skip_flags )
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{}
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~skip_flags_restorer()
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{
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_npo.skip_flags = _old_skip_flags;
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}
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node_property_object& _npo;
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uint32_t _old_skip_flags; // initialized in ctor
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};
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/**
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* Class used to help the without_pending_transactions
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* implementation.
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*
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* TODO: Change the name of this class to better reflect the fact
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* that it restores popped transactions as well as pending transactions.
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*/
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struct pending_transactions_restorer
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{
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pending_transactions_restorer( database& db, std::vector<processed_transaction>&& pending_transactions )
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: _db(db), _pending_transactions( std::move(pending_transactions) )
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{
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_db.clear_pending();
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}
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~pending_transactions_restorer()
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{
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for( const auto& tx : _db._popped_tx )
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{
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try {
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if( !_db.is_known_transaction( tx.id() ) ) {
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// since push_transaction() takes a signed_transaction,
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// the operation_results field will be ignored.
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_db._push_transaction( tx );
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}
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} catch ( const fc::exception& ) {
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}
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}
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_db._popped_tx.clear();
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for( const processed_transaction& tx : _pending_transactions )
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{
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try
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{
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if( !_db.is_known_transaction( tx.id() ) ) {
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// since push_transaction() takes a signed_transaction,
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// the operation_results field will be ignored.
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_db._push_transaction( tx );
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}
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}
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catch( const fc::exception& e )
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{
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/*
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wlog( "Pending transaction became invalid after switching to block ${b} ${t}", ("b", _db.head_block_id())("t",_db.head_block_time()) );
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wlog( "The invalid pending transaction caused exception ${e}", ("e", e.to_detail_string() ) );
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*/
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}
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}
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}
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database& _db;
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std::vector< processed_transaction > _pending_transactions;
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};
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/**
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* Set the skip_flags to the given value, call callback,
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* then reset skip_flags to their previous value after
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* callback is done.
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*/
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template< typename Lambda >
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void with_skip_flags(
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database& db,
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uint32_t skip_flags,
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Lambda callback )
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{
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node_property_object& npo = db.node_properties();
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skip_flags_restorer restorer( npo, npo.skip_flags );
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npo.skip_flags = skip_flags;
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callback();
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return;
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}
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/**
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* Empty pending_transactions, call callback,
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* then reset pending_transactions after callback is done.
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*
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* Pending transactions which no longer validate will be culled.
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*/
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template< typename Lambda >
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void without_pending_transactions(
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database& db,
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std::vector<processed_transaction>&& pending_transactions,
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Lambda callback )
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{
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pending_transactions_restorer restorer( db, std::move(pending_transactions) );
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callback();
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return;
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}
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} } } // graphene::chain::detail
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