Ref #17: Define types, logic, tests

This commit adds the BlockchainConfiguration type, which contains the
values to be voted on by producers. It also adds the algorithm to create
a BlockchainConfiguration containing the median values from a vector of
BlockchainConfigurations. Finally, it adds a testcase which verifies that
the median calculation is performed correctly.

libraries/chain/BlockchainConfiguration.cpp

@@ -0,0 +1,62 @@
+#include <eos/chain/BlockchainConfiguration.hpp>
+
+#include <boost/range/algorithm.hpp>
+
+#include <fc/io/json.hpp>
+
+namespace eos { namespace chain {
+
+template <typename T, typename Range>
+struct properties_median_calculator_visitor {
+   properties_median_calculator_visitor (T& medians, Range votes)
+      : medians(medians), votes(votes)
+   {}
+
+   template <typename Member, class Class, Member (Class::*member)>
+   void operator() (const char*) const {
+      auto median_itr = boost::begin(votes) + boost::distance(votes)/2;
+      boost::nth_element(votes, median_itr, [](const T& a, const T& b) { return a.*member < b.*member; });
+      medians.*member = (*median_itr).*member;
+   }
+
+   T& medians;
+   mutable Range votes;
+};
+template <typename T, typename Range>
+properties_median_calculator_visitor<T, Range> get_median_properties_calculator(T& medians, Range&& votes) {
+   return properties_median_calculator_visitor<T, Range>(medians, std::move(votes));
+}
+
+BlockchainConfiguration BlockchainConfiguration::get_median_values(
+      std::vector<BlockchainConfiguration> votes) {
+   BlockchainConfiguration results;
+   fc::reflector<BlockchainConfiguration>::visit(get_median_properties_calculator(results, std::move(votes)));
+   return results;
+}
+
+template <typename T>
+struct comparison_visitor {
+   const T& a;
+   const T& b;
+
+   template <typename Member, class Class, Member (Class::*member)>
+   void operator() (const char*) const {
+      if (a.*member != b.*member)
+         throw false;
+   }
+};
+
+bool BlockchainConfiguration::operator==(const BlockchainConfiguration& other) const {
+   try {
+      fc::reflector<BlockchainConfiguration>::visit(comparison_visitor<BlockchainConfiguration>{*this, other});
+   } catch (bool) {
+      return false;
+   }
+   return true;
+}
+
+std::ostream& operator<< (std::ostream& s, const BlockchainConfiguration& p) {
+   return s << fc::json::to_string(p);
+}
+
+} } // namespace eos::chain

libraries/chain/CMakeLists.txt

@@ -12,9 +12,9 @@ add_library( eos_chain
              get_config.cpp
 
              block_log.cpp
+             BlockchainConfiguration.cpp
 
              ${HEADERS}
-             ${PROTOCOL_HEADERS}
            )
 
 target_link_libraries( eos_chain fc chainbase eos_types wren )

libraries/chain/include/eos/chain/BlockchainConfiguration.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <eos/chain/types.hpp>
+
+#include <eos/types/generated.hpp>
+
+namespace eos {
+namespace chain {
+
+/**
+ * @brief Producer-voted blockchain configuration parameters
+ *
+ * This object stores the blockchain configuration, which is set by the block producers. Block producers each vote for
+ * their preference for each of the parameters in this object, and the blockchain runs according to the median of the
+ * values specified by the producers.
+ */
+struct BlockchainConfiguration : public types::BlockchainConfiguration {
+   using types::BlockchainConfiguration::BlockchainConfiguration;
+
+   static BlockchainConfiguration get_median_values(std::vector<BlockchainConfiguration> votes);
+
+   bool operator==(const BlockchainConfiguration& other) const;
+   friend std::ostream& operator<< (std::ostream& s, const BlockchainConfiguration& p);
+};
+
+}
+} // namespace eos::chain
+
+FC_REFLECT_DERIVED(eos::chain::BlockchainConfiguration, (eos::types::BlockchainConfiguration), )

libraries/chain/include/eos/chain/producer_object.hpp

@@ -23,6 +23,7 @@
  */
 #pragma once
 #include <eos/chain/types.hpp>
+#include <eos/chain/BlockchainConfiguration.hpp>
 
 #include "multi_index_includes.hpp"
 
@@ -37,6 +38,8 @@ namespace eos { namespace chain {
       public_key_type  signing_key;
       int64_t          total_missed = 0;
       uint32_t         last_confirmed_block_num = 0;
+
+      BlockchainConfiguration properties;
    };
 
    struct by_key;
@@ -60,4 +63,5 @@ FC_REFLECT(eos::chain::producer_object,
            (signing_key)
            (total_missed)
            (last_confirmed_block_num)
+           (properties)
           )

libraries/chain/include/eos/chain/types.hpp

@@ -113,6 +113,7 @@ namespace eos { namespace chain {
    using eos::types::AccountName;
    using eos::types::PermissionName;
    using eos::types::Asset;
+   using eos::types::ShareType;
    using eos::types::Authority;
    using eos::types::PermissionName;
    using eos::types::TypeName;

libraries/types/CMakeLists.txt

@@ -7,6 +7,7 @@ add_library( eos_types
              native.cpp
              ${HEADERS}
              "${CMAKE_CURRENT_SOURCE_DIR}/include/eos/types/generated.hpp"
+             types.eos
              )
 target_include_directories( eos_types PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/include" )
 target_link_libraries( eos_types eos_utilities fc )

libraries/types/types.eos

@@ -40,6 +40,14 @@ struct Authority
    keys      KeyPermissionWeight[]
    accounts  AccountPermissionWeight[]
 
+struct BlockchainConfiguration
+   maxBlockSize      UInt32
+   targetBlockSize   UInt32
+   maxStorageSize    UInt64
+   electedPay        ShareType
+   runnerUpPay       ShareType
+   minAccountBalance ShareType
+
 struct Transfer
    from      AccountName  # may not be the message.sender if message.sender has delegated authority by from
    to        AccountName

tests/tests/misc_tests.cpp

@@ -0,0 +1,36 @@
+#include <eos/chain/BlockchainConfiguration.hpp>
+
+#include <boost/test/unit_test.hpp>
+
+namespace eos {
+using namespace chain;
+
+BOOST_AUTO_TEST_SUITE(misc_tests)
+
+/// Test calculation of median values of blockchain operation properties
+BOOST_AUTO_TEST_CASE(median_properties_test)
+{ try {
+      vector<BlockchainConfiguration> votes{
+         {1024  , 512   , 4096  , Asset(5000   ).amount, Asset(4000   ).amount, Asset(100  ).amount},
+         {10000 , 100   , 4096  , Asset(3333   ).amount, Asset(27109  ).amount, Asset(10   ).amount},
+         {2048  , 1500  , 1000  , Asset(5432   ).amount, Asset(2000   ).amount, Asset(50   ).amount},
+         {100   , 25    , 1024  , Asset(90000  ).amount, Asset(0      ).amount, Asset(433  ).amount},
+         {1024  , 1000  , 100   , Asset(10     ).amount, Asset(50     ).amount, Asset(200  ).amount},
+      };
+      BlockchainConfiguration medians{
+         1024, 512, 1024, Asset(5000).amount, Asset(2000).amount, Asset(100).amount
+      };
+
+      BOOST_CHECK_EQUAL(BlockchainConfiguration::get_median_values(votes), medians);
+
+      votes.emplace_back(BlockchainConfiguration{1, 1, 1, 1, 1, 1});
+      votes.emplace_back(BlockchainConfiguration{1, 1, 1, 1, 1, 1});
+      medians = {1024, 100, 1000, Asset(3333).amount, Asset(50).amount, Asset(50).amount};
+
+      BOOST_CHECK_EQUAL(BlockchainConfiguration::get_median_values(votes), medians);
+      BOOST_CHECK_EQUAL(BlockchainConfiguration::get_median_values({medians}), medians);
+} FC_LOG_AND_RETHROW() }
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace eos