Add new API (asset_api) to query the full list of accounts that holds a specific asset

libraries/app/api.cpp

@@ -95,6 +95,10 @@ namespace graphene { namespace app {
        {
           _crypto_api = std::make_shared< crypto_api >();
        }
+       else if( api_name == "asset_api" )
+       {
+          _asset_api = std::make_shared< asset_api >( std::ref( *_app.chain_database() ) );
+       }
        else if( api_name == "debug_api" )
        {
           // can only enable this API if the plugin was loaded
@@ -217,6 +221,12 @@ namespace graphene { namespace app {
        return *_crypto_api;
     }
 
+    fc::api<asset_api> login_api::asset() const
+    {
+       FC_ASSERT(_asset_api);
+       return *_asset_api;
+    }
+
     fc::api<graphene::debug_witness::debug_api> login_api::debug() const
     {
        FC_ASSERT(_debug_api);
@@ -550,4 +560,32 @@ namespace graphene { namespace app {
        return fc::ecc::range_get_info( proof );
     }
 
+    // asset_api
+    asset_api::asset_api(graphene::chain::database& db) : _db(db) { }
+    asset_api::~asset_api() { }
+
+    vector<account_asset_balance> asset_api::get_asset_holders( asset_id_type asset_id ) const {
+
+      const auto& bal_idx = _db.get_index_type< account_balance_index >().indices().get< by_asset_balance >();
+      auto range = bal_idx.equal_range( boost::make_tuple( asset_id ) );
+
+      vector<account_asset_balance> result;
+
+      for( const account_balance_object& bal : boost::make_iterator_range( range.first, range.second ) )
+      {
+        if( bal.balance.value == 0 ) continue;
+
+        auto account = _db.find(bal.owner);
+
+        account_asset_balance aab;
+        aab.name       = account->name;
+        aab.account_id = account->id;
+        aab.amount     = bal.balance.value;
+
+        result.push_back(aab);
+      }
+
+      return result;
+    }
+
 } } // graphene::app

libraries/app/include/graphene/app/api.hpp

@@ -71,6 +71,13 @@ namespace graphene { namespace app {
       string                        message_out;
    };
 
+   struct account_asset_balance
+   {
+      string          name;
+      account_id_type account_id;
+      share_type      amount;
+   };
+
    /**
     * @brief The history_api class implements the RPC API for account history
     *
@@ -252,6 +259,21 @@ namespace graphene { namespace app {
          range_proof_info range_get_info( const std::vector<char>& proof );
    };
 
+   /**
+    * @brief
+    */
+   class asset_api
+   {
+      public:
+         asset_api(graphene::chain::database& db);
+         ~asset_api();
+
+         vector<account_asset_balance> get_asset_holders( asset_id_type asset_id )const;
+
+      private:
+         graphene::chain::database& _db;
+   };
+
    /**
     * @brief The login_api class implements the bottom layer of the RPC API
     *
@@ -283,6 +305,8 @@ namespace graphene { namespace app {
          fc::api<network_node_api> network_node()const;
          /// @brief Retrieve the cryptography API
          fc::api<crypto_api> crypto()const;
+         /// @brief Retrieve the asset API
+         fc::api<asset_api> asset()const;
          /// @brief Retrieve the debug API (if available)
          fc::api<graphene::debug_witness::debug_api> debug()const;
 
@@ -296,6 +320,7 @@ namespace graphene { namespace app {
          optional< fc::api<network_node_api> > _network_node_api;
          optional< fc::api<history_api> >  _history_api;
          optional< fc::api<crypto_api> > _crypto_api;
+         optional< fc::api<asset_api> > _asset_api;
          optional< fc::api<graphene::debug_witness::debug_api> > _debug_api;
    };
 
@@ -310,6 +335,8 @@ FC_REFLECT( graphene::app::verify_range_proof_rewind_result,
 //FC_REFLECT_TYPENAME( fc::ecc::compact_signature );
 //FC_REFLECT_TYPENAME( fc::ecc::commitment_type );
 
+FC_REFLECT( graphene::app::account_asset_balance, (name)(account_id)(amount) );
+
 FC_API(graphene::app::history_api,
        (get_account_history)
        (get_relative_account_history)
@@ -341,6 +368,9 @@ FC_API(graphene::app::crypto_api,
        (verify_range_proof_rewind)
        (range_get_info)
      )
+FC_API(graphene::app::asset_api,
+       (get_asset_holders)
+     )
 FC_API(graphene::app::login_api,
        (login)
        (network_broadcast)
@@ -348,5 +378,6 @@ FC_API(graphene::app::login_api,
        (history)
        (network_node)
        (crypto)
+       (asset)
        (debug)
      )