[Proof] Proof submission fee param (#779)

## Summary

This PR adds `ProofSubmissionFee` governance param as a `Coin` type.

It is based on PR #778 

## Issue

Proof messages take up a lot of block space. We need to deter submitting
unnecessary ones by making their submission payable by a governance
adjusted parameter.

The current PR is only about adding the governance param. The feature
itself will be submitted as a follow-up PR.

- #758 

## Type of change

Select one or more:

- [x] New feature, functionality or library
- [ ] Bug fix
- [ ] Code health or cleanup
- [ ] Documentation
- [ ] Other (specify)

## Testing

- [ ] **Documentation**: `make docusaurus_start`; only needed if you
make doc changes
- [x] **Unit Tests**: `make go_develop_and_test`
- [x] **LocalNet E2E Tests**: `make test_e2e`
- [ ] **DevNet E2E Tests**: Add the `devnet-test-e2e` label to the PR.

## Sanity Checklist

- [x] I have tested my changes using the available tooling
- [x] I have commented my code
- [x] I have performed a self-review of my own code; both comments &
source code
- [ ] I create and reference any new tickets, if applicable
- [x] I have left TODOs throughout the codebase, if applicable

Makefile

@@ -942,6 +942,10 @@ params_update_proof_proof_requirement_threshold: ## Update the proof module proo
 params_update_proof_proof_missing_penalty: ## Update the proof module proof_missing_penalty param
 	poktrolld tx authz exec ./tools/scripts/params/proof_proof_missing_penalty.json $(PARAM_FLAGS)
 
+.PHONY: params_update_proof_proof_submission_fee
+params_update_proof_proof_submission_fee: ## Update the proof module proof_submission_fee param
+	poktrolld tx authz exec ./tools/scripts/params/proof_proof_submission_fee.json $(PARAM_FLAGS)
+
 ### Shared Module Params ###
 .PHONY: params_update_shared_all
 params_update_shared_all: ## Update the session module params

config.yml

@@ -239,6 +239,9 @@ genesis:
         proof_missing_penalty:
           amount: "320"
           denom: upokt
+        proof_submission_fee:
+          amount: "1000000"
+          denom: upokt
     shared:
       params:
         num_blocks_per_session: 10

e2e/tests/parse_params_test.go

@@ -141,6 +141,8 @@ func (s *suite) newProofMsgUpdateParams(params paramsMap) cosmostypes.Msg {
 			msgUpdateParams.Params.ProofRequirementThreshold = uint64(paramValue.value.(int64))
 		case prooftypes.ParamProofMissingPenalty:
 			msgUpdateParams.Params.ProofMissingPenalty = paramValue.value.(*cosmostypes.Coin)
+		case prooftypes.ParamProofSubmissionFee:
+			msgUpdateParams.Params.ProofSubmissionFee = paramValue.value.(*cosmostypes.Coin)
 		default:
 			s.Fatalf("ERROR: unexpected %q type param name %q", paramValue.typeStr, paramName)
 		}

e2e/tests/update_params.feature

@@ -42,6 +42,7 @@ Feature: Params Namespace
       | proof_request_probability    | 0.1                                                              | float |
       | proof_requirement_threshold  | 100                                                              | int64 |
       | proof_missing_penalty        | 500                                                              | coin  |
+      | proof_submission_fee         | 5000000                                                          | coin  |
     Then all "proof" module params should be updated
 
   # NB: If you are reading this and the proof module has parameters
@@ -92,6 +93,7 @@ Feature: Params Namespace
       | proof      | /poktroll.proof.MsgUpdateParam      | proof_request_probability             | 0.1         | float      |
       | proof      | /poktroll.proof.MsgUpdateParam      | proof_requirement_threshold           | 100         | int64      |
       | proof      | /poktroll.proof.MsgUpdateParam      | proof_missing_penalty                 | 500         | coin       |
+      | proof      | /poktroll.proof.MsgUpdateParam      | proof_submission_fee                  | 5000000     | coin       |
       | shared     | /poktroll.shared.MsgUpdateParam     | num_blocks_per_session                | 5           | int64      |
       | shared     | /poktroll.shared.MsgUpdateParam     | grace_period_end_offset_blocks        | 2           | int64      |
       | shared     | /poktroll.shared.MsgUpdateParam     | claim_window_open_offset_blocks       | 2           | int64      |

e2e/tests/update_params_test.go

@@ -393,6 +393,11 @@ func (s *suite) assertExpectedModuleParamsUpdated(moduleName string) {
 			params.ProofMissingPenalty = proofMissingPenalty.value.(*cosmostypes.Coin)
 		}
 
+		proofSubmissionFee, ok := paramsMap[prooftypes.ParamProofSubmissionFee]
+		if ok {
+			params.ProofSubmissionFee = proofSubmissionFee.value.(*cosmostypes.Coin)
+		}
+
 		assertUpdatedParams(s,
 			[]byte(res.Stdout),
 			&prooftypes.QueryParamsResponse{

proto/poktroll/proof/params.proto

@@ -34,6 +34,12 @@ message Params {
   // but is not provided.
   cosmos.base.v1beta1.Coin proof_missing_penalty = 4 [(gogoproto.jsontag) = "proof_missing_penalty"];
 
+  // proof_submission_fee is the number of tokens (uPOKT) which should be paid by
+  // the supplier operator when submitting a proof.
+  // This is needed to account for the cost of storing proofs on-chain and prevent
+  // spamming (i.e. sybil bloat attacks) the network with non-required proofs.
+  cosmos.base.v1beta1.Coin proof_submission_fee = 5 [(gogoproto.jsontag) = "proof_submission_fee"];
+
   // IMPORTANT: Make sure to update all related files if you're modifying or adding a new parameter.
   // Try the following grep to find all related places: `grep -r compute_units_to_tokens_multiplier`
   // TODO_IMPROVE: Look into an opportunity to use an enum to avoid using strings throughout the codebase.

tools/scripts/params/proof_all.json

@@ -11,6 +11,10 @@
           "proof_missing_penalty": {
             "amount": "320",
             "denom": "upokt"
+          },
+          "proof_submission_fee": {
+            "amount": "1000000",
+            "denom": "upokt"
           }
         }
       }

tools/scripts/params/proof_proof_submission_fee.json

@@ -0,0 +1,15 @@
+{
+  "body": {
+    "messages": [
+      {
+        "@type": "/poktroll.proof.MsgUpdateParam",
+        "authority": "pokt10d07y265gmmuvt4z0w9aw880jnsr700j8yv32t",
+        "name": "proof_submission_fee",
+        "as_coin": {
+          "denom": "upokt",
+          "amount": "1000000"
+        }
+      }
+    ]
+  }
+}

x/proof/keeper/msg_server_update_param.go

@@ -71,6 +71,18 @@ func (k msgServer) UpdateParam(
 		}
 
 		params.ProofMissingPenalty = proofMissingPenalty
+	case types.ParamProofSubmissionFee:
+		value, ok := msg.AsType.(*types.MsgUpdateParam_AsCoin)
+		if !ok {
+			return nil, types.ErrProofParamInvalid.Wrapf("unsupported value type for %s param: %T", msg.Name, msg.AsType)
+		}
+		proofSubmissionFee := value.AsCoin
+
+		if err := types.ValidateProofSubmissionFee(proofSubmissionFee); err != nil {
+			return nil, err
+		}
+
+		params.ProofSubmissionFee = proofSubmissionFee
 	default:
 		return nil, types.ErrProofParamInvalid.Wrapf("unsupported param %q", msg.Name)
 	}