godoc++

x/auth/middleware/fee.go

@@ -30,7 +30,17 @@ func MempoolFeeMiddleware(txh tx.Handler) tx.Handler {
 	}
 }
 
-// CheckTx implements tx.Handler.CheckTx.
+// CheckTx implements tx.Handler.CheckTx. It is responsible for determining if a
+// transaction's fees meet the required minimum of the processing node. Note, a
+// node can have zero fees set as the minimum. If non-zero minimum fees are set
+// and the transaction does not meet the minimum, the transaction is rejected.
+//
+// Recall, a transaction's fee is determined by ceil(minGasPrice * gasLimit).
+// In addition, we set the Priority of the transaction to be ordered in the
+// Tendermint mempool based naively on the total sum of all fees included.
+// Applications that need more sophisticated mempool ordering should look to
+// implement their own fee handling middleware instead of using
+// mempoolFeeTxHandler.
 func (txh mempoolFeeTxHandler) CheckTx(ctx context.Context, tx sdk.Tx, req abci.RequestCheckTx) (abci.ResponseCheckTx, error) {
 	sdkCtx := sdk.UnwrapSDKContext(ctx)