Merge pull request #1403 from PaulVMo/h3dex-remove-gateway-fix

bugfix for removing gateway from h3dex

include/blockchain_vars.hrl

@@ -219,6 +219,9 @@
 %% max number of hexes to GC in the h3dex per block: integer
 -define(h3dex_gc_width, h3dex_gc_width).
 
+%% determines whether or not to use the fix for a bug in removing gateways from h3dex : boolean
+-define(h3dex_remove_gw_fix, h3dex_remove_gw_fix).
+
 %% the version number of poc targeting in use: integer
 %% if not set, code paths with default to 3 ( blockchain_poc_target_v3 )
 -define(poc_targeting_version, poc_targeting_version).

src/ledger/v1/blockchain_ledger_v1.erl

@@ -5138,16 +5138,24 @@ remove_gw_from_h3dex(Hex, GWAddr, Res, Ledger) ->
         {ok, BinGws} ->
             case lists:delete(GWAddr, binary_to_term(BinGws)) of
                 [] ->
-                    case count_gateways_in_hex(h3:parent(Hex, Res), Ledger) of
-                        0 ->
-                            %% removing a hex means we need to recalculate the set of populated
-                            %% hexes
-                            build_random_hex_targeting_lookup(Res, Ledger);
+                    %% need to remove the hex and maybe recalc targeting lookup if no gateways remain in parent hex
+                    %% includes chain var protected bug fix
+                    case config(?h3dex_remove_gw_fix, Ledger) of
+                        %% if fix enabled, delete the hex first, then count the parent hex's gateways
+                        {ok, true} ->
+                            cache_delete(Ledger, H3CF, BinHex),
+                            case count_gateways_in_hex(h3:parent(Hex, Res), Ledger) of
+                                0 -> build_random_hex_targeting_lookup(Res, Ledger);
+                                _ -> ok
+                            end;
+                        %% otherwise, keep the wrong behavior of counting gateways then deleting the hex
                         _ ->
-                            ok
-                    end,
-
-                    cache_delete(Ledger, H3CF, BinHex);
+                            case count_gateways_in_hex(h3:parent(Hex, Res), Ledger) of
+                                0 -> build_random_hex_targeting_lookup(Res, Ledger);
+                                _ -> ok
+                            end,
+                            cache_delete(Ledger, H3CF, BinHex)
+                    end;
                 NewGWs ->
                     cache_put(Ledger, H3CF, BinHex, term_to_binary(lists:sort(NewGWs), [compressed]))
             end;

src/transactions/v1/blockchain_txn_vars_v1.erl

@@ -1136,6 +1136,11 @@ validate_var(?polyfill_resolution, Value) ->
     validate_int(Value, "polyfill_resolution", 0, 15, false);
 validate_var(?h3dex_gc_width, Value) ->
   validate_int(Value, "h3dex_gc_width", 1, 10000, false);
+validate_var(?h3dex_remove_gw_fix, Value) ->
+  case Value of
+        Val when is_boolean(Val) -> ok;
+        _ -> throw({error, {h3dex_gw_remove_fix, Value}})
+    end;
 validate_var(?poc_target_pool_size, Value) ->
   validate_int(Value, "poc_target_pool_size", 1, 1000000, false);
 validate_var(?poc_targeting_version, Value) ->