From da99f11be3077daf9ee587e6b0087794dc74f3c5 Mon Sep 17 00:00:00 2001
From: crypto-facs <84574577+crypto-facs@users.noreply.github.com>
Date: Fri, 3 Jun 2022 15:31:57 +0200
Subject: [PATCH] rpc: Update `GetGasPrice` RPC endpoint with global
 `MinGasPrice` (#1108)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* return MinGasPrice as minium on GetGasPrice api

* update logic

* update changelog

* globalmingsprice comment

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>
---
 CHANGELOG.md                       |  1 +
 rpc/backend/backend.go             |  1 +
 rpc/backend/evm_backend.go         |  9 +++++++++
 rpc/namespaces/ethereum/eth/api.go | 10 ++++++++++
 4 files changed, 21 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecfee6d5..4860072d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 - (rpc) [tharsis#1081](https://github.com/tharsis/ethermint/pull/1081) Deduplicate some json-rpc logic codes, cleanup several dead functions.
 - (ante) [tharsis#1062](https://github.com/tharsis/ethermint/pull/1062) Emit event of eth tx hash in ante handler to support query failed transactions.
 - (analytics) [tharsis#1106](https://github.com/tharsis/ethermint/pull/1106) Update telemetry to Ethermint modules.
+- (rpc) [tharsis#1108](https://github.com/tharsis/ethermint/pull/1108) Update GetGasPrice RPC endpoint with global `MinGasPrice`
 
 ### Improvements
 
diff --git a/rpc/backend/backend.go b/rpc/backend/backend.go
index e9692c8d..49b456f7 100644
--- a/rpc/backend/backend.go
+++ b/rpc/backend/backend.go
@@ -69,6 +69,7 @@ type EVMBackend interface {
 	GetTxByTxIndex(height int64, txIndex uint) (*tmrpctypes.ResultTx, error)
 	EstimateGas(args evmtypes.TransactionArgs, blockNrOptional *types.BlockNumber) (hexutil.Uint64, error)
 	BaseFee(height int64) (*big.Int, error)
+	GlobalMinGasPrice() (sdk.Dec, error)
 
 	// Fee API
 	FeeHistory(blockCount rpc.DecimalOrHex, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (*types.FeeHistoryResult, error)
diff --git a/rpc/backend/evm_backend.go b/rpc/backend/evm_backend.go
index 81887bd6..d5d8a84a 100644
--- a/rpc/backend/evm_backend.go
+++ b/rpc/backend/evm_backend.go
@@ -818,6 +818,15 @@ func (b *Backend) BaseFee(height int64) (*big.Int, error) {
 	return res.BaseFee.BigInt(), nil
 }
 
+// GlobalMinGasPrice returns MinGasPrice param from FeeMarket
+func (b *Backend) GlobalMinGasPrice() (sdk.Dec, error) {
+	res, err := b.queryClient.FeeMarket.Params(b.ctx, &feemarkettypes.QueryParamsRequest{})
+	if err != nil {
+		return sdk.ZeroDec(), err
+	}
+	return res.Params.MinGasPrice, nil
+}
+
 // FeeHistory returns data relevant for fee estimation based on the specified range of blocks.
 func (b *Backend) FeeHistory(
 	userBlockCount rpc.DecimalOrHex, // number blocks to fetch, maximum is 100
diff --git a/rpc/namespaces/ethereum/eth/api.go b/rpc/namespaces/ethereum/eth/api.go
index 2086e37a..07add625 100644
--- a/rpc/namespaces/ethereum/eth/api.go
+++ b/rpc/namespaces/ethereum/eth/api.go
@@ -211,6 +211,16 @@ func (e *PublicAPI) GasPrice() (*hexutil.Big, error) {
 		result = big.NewInt(e.backend.RPCMinGasPrice())
 	}
 
+	// return at least GlobalMinGasPrice from FeeMarket module
+	minGasPrice, err := e.backend.GlobalMinGasPrice()
+	if err != nil {
+		return nil, err
+	}
+	minGasPriceInt := minGasPrice.BigInt()
+	if result.Cmp(minGasPriceInt) < 0 {
+		result = minGasPriceInt
+	}
+
 	return (*hexutil.Big)(result), nil
 }