Implement rex maturity changes

ref: eosnetworkfoundation/eos-system-contracts#132

contracts/eosio.system/include/eosio.system/eosio.system.hpp

@@ -539,6 +539,14 @@ namespace eosiosystem {
    typedef eosio::multi_index< "rexqueue"_n, rex_order,
                                indexed_by<"bytime"_n, const_mem_fun<rex_order, uint64_t, &rex_order::by_time>>> rex_order_table;
 
+   struct [[eosio::table("rexmaturity"),eosio::contract("eosio.system")]] rex_maturity {
+      uint32_t num_of_maturity_buckets = 5;
+
+      EOSLIB_SERIALIZE( rex_maturity, (num_of_maturity_buckets) )
+   };
+
+   typedef eosio::singleton<"rexmaturity"_n, rex_maturity> rex_maturity_singleton;
+
    struct rex_order_outcome {
       bool success;
       asset proceeds;
@@ -720,6 +728,7 @@ namespace eosiosystem {
          rex_fund_table           _rexfunds;
          rex_balance_table        _rexbalance;
          rex_order_table          _rexorders;
+         rex_maturity_singleton   _rexmaturity;
 
       public:
          static constexpr eosio::name active_permission{"active"_n};
@@ -1079,6 +1088,14 @@ namespace eosiosystem {
          [[eosio::action]]
          void closerex( const name& owner );
 
+         /**
+          * Facilitates the modification of REX maturity buckets
+          *
+          * @param num_of_maturity_buckets - used to calculate maturity time of purchase REX tokens from end of the day UTC.
+          */
+         [[eosio::action]]
+         void rexmaturity(const uint32_t num_of_maturity_buckets);
+
          /**
           * Undelegate bandwidth action, decreases the total tokens delegated by `from` to `receiver` and/or
           * frees the memory associated with the delegation if there is nothing
@@ -1569,7 +1586,7 @@ namespace eosiosystem {
          bool rex_loans_available()const;
          bool rex_system_initialized()const { return _rexpool.begin() != _rexpool.end(); }
          bool rex_available()const { return rex_system_initialized() && _rexpool.begin()->total_rex.amount > 0; }
-         static time_point_sec get_rex_maturity();
+         static time_point_sec get_rex_maturity(const name& system_account_name = "eosio"_n );
          asset add_to_rex_balance( const name& owner, const asset& payment, const asset& rex_received );
          asset add_to_rex_pool( const asset& payment );
          void add_to_rex_return_pool( const asset& fee );

contracts/eosio.system/src/eosio.system.cpp

@@ -30,7 +30,8 @@ namespace eosiosystem {
     _rexretbuckets(get_self(), get_self().value),
     _rexfunds(get_self(), get_self().value),
     _rexbalance(get_self(), get_self().value),
-    _rexorders(get_self(), get_self().value)
+    _rexorders(get_self(), get_self().value),
+    _rexmaturity(get_self(), get_self().value)
    {
       _gstate  = _global.exists() ? _global.get() : get_default_parameters();
       _gstate2 = _global2.exists() ? _global2.get() : eosio_global_state2{};

contracts/eosio.system/src/rex.cpp

@@ -8,6 +8,20 @@ namespace eosiosystem {
    using eosio::token;
    using eosio::seconds;
 
+   void system_contract::rexmaturity(const uint32_t num_of_maturity_buckets)
+   {
+      require_auth(get_self());
+
+      check(num_of_maturity_buckets > 0, "num_of_maturity_buckets must be positive");
+      check(num_of_maturity_buckets <= 30, "num_of_maturity_buckets must be less than or equal to 30");
+
+      auto state = _rexmaturity.get_or_default();
+      if ( _rexmaturity.exists() ) check(state.num_of_maturity_buckets != num_of_maturity_buckets, "num_of_maturity_buckets is the same as the current value");
+
+      state.num_of_maturity_buckets = num_of_maturity_buckets;
+      _rexmaturity.set(state, get_self());
+   }
+
    void system_contract::deposit( const name& owner, const asset& amount )
    {
       require_auth( owner );
@@ -959,9 +973,10 @@ namespace eosiosystem {
     *
     * @return time_point_sec
     */
-   time_point_sec system_contract::get_rex_maturity()
+   time_point_sec system_contract::get_rex_maturity( const name& system_account_name )
    {
-      const uint32_t num_of_maturity_buckets = 5;
+      rex_maturity_singleton _rexmaturity(system_account_name, system_account_name.value);
+      const uint32_t num_of_maturity_buckets = _rexmaturity.get_or_default().num_of_maturity_buckets; // default 5
       static const uint32_t now = current_time_point().sec_since_epoch();
       static const uint32_t r   = now % seconds_per_day;
       static const time_point_sec rms{ now - r + num_of_maturity_buckets * seconds_per_day };