set_finalizers host function (#1511)

Work in progress.

- Implemented host function (not tested);
- Finalizer set types;
- Placeholders for fc::crypto::blslib::bls_public_key operators == != and <;
- Stub notify_set_finalizers signal to be connected to chain_plugin, to reach chain_pacemaker

libraries/chain/controller.cpp

@@ -1990,6 +1990,10 @@ struct controller_impl {
       emit( self.new_hs_new_block_message, msg );
    }
 
+   void set_finalizers_impl(uint64_t fthreshold, vector<finalizer_authority> finalizers) {
+      emit( self.notify_set_finalizers, std::tie(fthreshold, finalizers) );
+   }
+
    /**
     *  This method is called from other threads. The controller_impl should outlive those threads.
     *  However, to avoid race conditions, it means that the behavior of this function should not change
@@ -3313,6 +3317,10 @@ int64_t controller::set_proposed_producers( vector<producer_authority> producers
    return version;
 }
 
+void controller::set_finalizers( uint64_t fthreshold, vector<finalizer_authority> finalizers ) {
+   my->set_finalizers_impl(fthreshold, finalizers);
+}
+
 const producer_authority_schedule&    controller::active_producers()const {
    if( !(my->pending) )
       return  my->head->active_schedule;

libraries/chain/include/eosio/chain/config.hpp

@@ -130,6 +130,10 @@ const static int max_producers = 125;
 const static size_t maximum_tracked_dpos_confirmations = 1024;     ///<
 static_assert(maximum_tracked_dpos_confirmations >= ((max_producers * 2 / 3) + 1) * producer_repetitions, "Settings never allow for DPOS irreversibility" );
 
+/**
+ * Maximum number of finalizers in the finalizer set
+ */
+const static int max_finalizers = max_producers;
 
 /**
  * The number of blocks produced per round is based upon all producers having a chance

libraries/chain/include/eosio/chain/controller.hpp

@@ -10,6 +10,8 @@
 #include <eosio/chain/protocol_feature_manager.hpp>
 #include <eosio/chain/webassembly/eos-vm-oc/config.hpp>
 
+#include <eosio/chain/finalizer_set.hpp>
+
 namespace chainbase {
    class database;
 }
@@ -306,6 +308,8 @@ namespace eosio { namespace chain {
 
          int64_t set_proposed_producers( vector<producer_authority> producers );
 
+         void set_finalizers( uint64_t fthreshold, vector<finalizer_authority> finalizers );
+
          bool light_validation_allowed() const;
          bool skip_auth_check()const;
          bool skip_trx_checks()const;
@@ -356,6 +360,7 @@ namespace eosio { namespace chain {
          signal<void(const hs_vote_message_ptr&)> new_hs_vote_message;
          signal<void(const hs_new_view_message_ptr&)>    new_hs_new_view_message;
          signal<void(const hs_new_block_message_ptr&)> new_hs_new_block_message;
+         signal<void(std::tuple<const uint64_t, const vector<finalizer_authority>&>)> notify_set_finalizers;
 
          /*
          signal<void()>                                  pre_apply_block;

libraries/chain/include/eosio/chain/finalizer_set.hpp

@@ -0,0 +1,144 @@
+#pragma once
+
+#include <eosio/chain/config.hpp>
+#include <eosio/chain/types.hpp>
+#include <chainbase/chainbase.hpp>
+#include <eosio/chain/authority.hpp>
+#include <eosio/chain/snapshot.hpp>
+
+#include <fc/crypto/bls_public_key.hpp>
+
+namespace eosio::chain {
+
+   struct shared_finalizer_authority {
+      shared_finalizer_authority() = delete;
+      shared_finalizer_authority( const shared_finalizer_authority& ) = default;
+      shared_finalizer_authority( shared_finalizer_authority&& ) = default;
+      shared_finalizer_authority& operator= ( shared_finalizer_authority && ) = default;
+      shared_finalizer_authority& operator= ( const shared_finalizer_authority & ) = default;
+
+      shared_finalizer_authority( const name& finalizer_name, const uint64_t fweight, const fc::crypto::blslib::bls_public_key& public_key )
+      :finalizer_name(finalizer_name)
+      ,fweight(fweight)
+      ,public_key(public_key)
+      {}
+
+      name             finalizer_name;
+      uint64_t         fweight;
+      fc::crypto::blslib::bls_public_key   public_key;
+   };
+
+   struct shared_finalizer_set {
+      shared_finalizer_set() = delete;
+
+      explicit shared_finalizer_set( chainbase::allocator<char> alloc )
+      :finalizers(alloc){}
+
+      shared_finalizer_set( const shared_finalizer_set& ) = default;
+      shared_finalizer_set( shared_finalizer_set&& ) = default;
+      shared_finalizer_set& operator= ( shared_finalizer_set && ) = default;
+      shared_finalizer_set& operator= ( const shared_finalizer_set & ) = default;
+
+      uint32_t                                   version = 0; ///< sequentially incrementing version number
+      uint64_t                                   fthreshold = 0; // minimum finalizer fweight sum for block finalization
+      shared_vector<shared_finalizer_authority>  finalizers;
+   };
+
+   struct finalizer_authority {
+
+      name      finalizer_name;
+      uint64_t  fweight; // weight that this finalizer's vote has for meeting fthreshold
+      fc::crypto::blslib::bls_public_key  public_key;
+
+      auto to_shared(chainbase::allocator<char> alloc) const {
+         return shared_finalizer_authority(finalizer_name, fweight, public_key);
+      }
+
+      static auto from_shared( const shared_finalizer_authority& src ) {
+         finalizer_authority result;
+         result.finalizer_name = src.finalizer_name;
+         result.fweight = src.fweight;
+         result.public_key = src.public_key;
+         return result;
+      }
+
+      /**
+       * ABI's for contracts expect variants to be serialized as a 2 entry array of
+       * [type-name, value].
+       *
+       * This is incompatible with standard FC rules for
+       * static_variants which produce
+       *
+       * [ordinal, value]
+       *
+       * this method produces an appropriate variant for contracts where the authority field
+       * is correctly formatted
+       */
+      fc::variant get_abi_variant() const;
+
+      friend bool operator == ( const finalizer_authority& lhs, const finalizer_authority& rhs ) {
+         return tie( lhs.finalizer_name, lhs.fweight, lhs.public_key ) == tie( rhs.finalizer_name, rhs.fweight, rhs.public_key );
+      }
+      friend bool operator != ( const finalizer_authority& lhs, const finalizer_authority& rhs ) {
+         return tie( lhs.finalizer_name, lhs.fweight, lhs.public_key ) != tie( rhs.finalizer_name, rhs.fweight, rhs.public_key );
+      }
+   };
+
+   struct finalizer_set {
+      finalizer_set() = default;
+
+      finalizer_set( uint32_t version, uint64_t fthreshold, std::initializer_list<finalizer_authority> finalizers )
+      :version(version)
+      ,fthreshold(fthreshold)
+      ,finalizers(finalizers)
+      {}
+
+      auto to_shared(chainbase::allocator<char> alloc) const {
+         auto result = shared_finalizer_set(alloc);
+         result.version = version;
+         result.fthreshold = fthreshold;
+         result.finalizers.clear();
+         result.finalizers.reserve( finalizers.size() );
+         for( const auto& f : finalizers ) {
+            result.finalizers.emplace_back(f.to_shared(alloc));
+         }
+         return result;
+      }
+
+      static auto from_shared( const shared_finalizer_set& src ) {
+         finalizer_set result;
+         result.version = src.version;
+         result.fthreshold = src.fthreshold;
+         result.finalizers.reserve( src.finalizers.size() );
+         for( const auto& f : src.finalizers ) {
+            result.finalizers.emplace_back(finalizer_authority::from_shared(f));
+         }
+         return result;
+      }
+
+      uint32_t                                       version = 0; ///< sequentially incrementing version number
+      uint64_t                                       fthreshold;  // vote fweight threshold to finalize blocks
+      vector<finalizer_authority>                    finalizers; // Instant Finality voter set
+
+      friend bool operator == ( const finalizer_set& a, const finalizer_set& b )
+      {
+         if( a.version != b.version ) return false;
+         if( a.fthreshold != b.fthreshold ) return false;
+         if ( a.finalizers.size() != b.finalizers.size() ) return false;
+         for( uint32_t i = 0; i < a.finalizers.size(); ++i )
+            if( ! (a.finalizers[i] == b.finalizers[i]) ) return false;
+         return true;
+      }
+
+      friend bool operator != ( const finalizer_set& a, const finalizer_set& b )
+      {
+         return !(a==b);
+      }
+   };
+
+} /// eosio::chain
+
+FC_REFLECT( eosio::chain::finalizer_authority, (finalizer_name)(fweight)(public_key) )
+FC_REFLECT( eosio::chain::finalizer_set, (version)(fthreshold)(finalizers) )
+FC_REFLECT( eosio::chain::shared_finalizer_authority, (finalizer_name)(fweight)(public_key) )
+FC_REFLECT( eosio::chain::shared_finalizer_set, (version)(fthreshold)(finalizers) )

libraries/chain/include/eosio/chain/webassembly/interface.hpp

@@ -173,6 +173,15 @@ namespace webassembly {
          */
          int64_t set_proposed_producers_ex(uint64_t packed_producer_format, legacy_span<const char> packed_producer_schedule);
 
+         /**
+          * Submits a finalizer set change to Hotstuff.
+          *
+          * @ingroup privileged
+          *
+          * @param packed_finalizer_set - a serialized finalizer_set object.
+         */
+         void set_finalizers(legacy_span<const char> packed_finalizer_set);
+
          /**
           * Retrieve the blockchain config parameters.
           *

libraries/chain/webassembly/privileged.cpp

@@ -5,6 +5,7 @@
 #include <eosio/chain/transaction_context.hpp>
 #include <eosio/chain/resource_limits.hpp>
 #include <eosio/chain/apply_context.hpp>
+#include <eosio/chain/finalizer_set.hpp>
 
 #include <fc/io/datastream.hpp>
 
@@ -150,6 +151,35 @@ namespace eosio { namespace chain { namespace webassembly {
       }
    }
 
+   void interface::set_finalizers(legacy_span<const char> packed_finalizer_set) {
+      EOS_ASSERT(!context.trx_context.is_read_only(), wasm_execution_error, "set_proposed_finalizers not allowed in a readonly transaction");
+      fc::datastream<const char*> ds( packed_finalizer_set.data(), packed_finalizer_set.size() );
+      finalizer_set finset;
+      fc::raw::unpack(ds, finset);
+      vector<finalizer_authority> & finalizers = finset.finalizers;
+
+      EOS_ASSERT( finalizers.size() <= config::max_finalizers, wasm_execution_error, "Finalizer set exceeds the maximum finalizer count for this chain" );
+      EOS_ASSERT( finalizers.size() > 0, wasm_execution_error, "Finalizer set cannot be empty" );
+
+      std::set<fc::crypto::blslib::bls_public_key> unique_finalizer_keys;
+      std::set<account_name> unique_finalizers;
+      uint64_t f_weight_sum = 0;
+
+      for (const auto& f: finalizers) {
+         EOS_ASSERT( context.is_account(f.finalizer_name), wasm_execution_error, "Finalizer set includes a nonexisting account" );
+         EOS_ASSERT( f.public_key.valid(), wasm_execution_error, "Finalizer set includes an invalid key" );
+         f_weight_sum += f.fweight;
+         unique_finalizer_keys.insert(f.public_key);
+         unique_finalizers.insert(f.finalizer_name);
+      }
+
+      EOS_ASSERT( finalizers.size() == unique_finalizers.size(), wasm_execution_error, "Duplicate finalizer name in finalizer set" );
+      EOS_ASSERT( finalizers.size() == unique_finalizer_keys.size(), wasm_execution_error, "Duplicate finalizer bls key in finalizer set" );
+      EOS_ASSERT( finset.fthreshold > f_weight_sum / 2, wasm_execution_error, "Finalizer set treshold cannot be met by finalizer weights" );
+
+      context.control.set_finalizers( finset.fthreshold, std::move(finalizers) );
+   }
+
    uint32_t interface::get_blockchain_parameters_packed( legacy_span<char> packed_blockchain_parameters ) const {
       auto& gpo = context.control.get_global_properties();
 

libraries/libfc/include/fc/crypto/bls_public_key.hpp

@@ -60,9 +60,10 @@ namespace fc { namespace crypto { namespace blslib {
 
 
          friend std::ostream& operator<< (std::ostream& s, const bls_public_key& k);
-         //friend bool operator == ( const bls_public_key& p1, const bls_public_key& p2);
-         //friend bool operator != ( const bls_public_key& p1, const bls_public_key& p2);
-         //friend bool operator < ( const bls_public_key& p1, const bls_public_key& p2);
+#warning FIXME/TODO: Must implement these operators. 
+      friend bool operator == ( const bls_public_key& p1, const bls_public_key& p2) { return false; /*p1._pkey == p2._pkey;*/ }
+      friend bool operator != ( const bls_public_key& p1, const bls_public_key& p2) { return false; /*p1._pkey != p2._pkey;*/ }
+      friend bool operator < ( const bls_public_key& p1, const bls_public_key& p2) { return false; /*p1._pkey < p2._pkey;*/ }
          friend struct reflector<bls_public_key>;
          friend class bls_private_key;
    }; // bls_public_key