[rosetta] Mempool Endpoint (#3339)

* [rosetta] Implement mempool endpoint

	* [block] Make FormatTransaction public to use in the Mempool
	* [mempool] Create Transaction for /mempool/transaction using estimated transaction receipt

* [rosetta] Add Mempool API to the Router

* [rosetta] Update block test file with public function

* [rosetta] Add comments to explain estimated transaction receipt

* [rosetta] Revert making function public

* [rosetta] Fix hash conversion for looking up transaction in pool

* [rosetta] Fix lint

* [rosetta] Fix lint (again)

* [rosetta] Fake logs for CollectReward transaction

* [rosetta] Fix lint

* [rosetta] Fix lint again...

rosetta/rosetta.go

@@ -76,9 +76,10 @@ func newHTTPServer(handler http.Handler) *http.Server {
 
 func getRouter(asserter *asserter.Asserter, hmy *hmy.Harmony) http.Handler {
 	return server.NewRouter(
-		server.NewNetworkAPIController(services.NewNetworkAPI(hmy), asserter),
-		server.NewBlockAPIController(services.NewBlockAPI(hmy), asserter),
 		server.NewAccountAPIController(services.NewAccountAPI(hmy), asserter),
+		server.NewBlockAPIController(services.NewBlockAPI(hmy), asserter),
+		server.NewMempoolAPIController(services.NewMempoolAPI(hmy), asserter),
+		server.NewNetworkAPIController(services.NewNetworkAPI(hmy), asserter),
 	)
 }
 

rosetta/services/mempool.go

@@ -0,0 +1,95 @@
+package services
+
+import (
+	"context"
+	"math/big"
+
+	"github.com/coinbase/rosetta-sdk-go/server"
+	"github.com/coinbase/rosetta-sdk-go/types"
+	ethCommon "github.com/ethereum/go-ethereum/common"
+	hmyTypes "github.com/harmony-one/harmony/core/types"
+	"github.com/harmony-one/harmony/hmy"
+	"github.com/harmony-one/harmony/rosetta/common"
+	"github.com/harmony-one/harmony/staking"
+)
+
+// MempoolAPI implements the server.MempoolAPIServicer interface
+type MempoolAPI struct {
+	hmy *hmy.Harmony
+}
+
+// NewMempoolAPI creates a new instance of MempoolAPI
+func NewMempoolAPI(hmy *hmy.Harmony) server.MempoolAPIServicer {
+	return &MempoolAPI{
+		hmy: hmy,
+	}
+}
+
+// Mempool ...
+func (s *MempoolAPI) Mempool(
+	ctx context.Context, req *types.NetworkRequest,
+) (*types.MempoolResponse, *types.Error) {
+	if err := assertValidNetworkIdentifier(req.NetworkIdentifier, s.hmy.ShardID); err != nil {
+		return nil, err
+	}
+
+	pool, err := s.hmy.GetPoolTransactions()
+	if err != nil {
+		return nil, common.NewError(common.CatchAllError, map[string]interface{}{
+			"message": "unable to fetch pool transactions",
+		})
+	}
+	txIDs := make([]*types.TransactionIdentifier, pool.Len())
+	for i, tx := range pool {
+		txIDs[i] = &types.TransactionIdentifier{
+			Hash: tx.Hash().String(),
+		}
+	}
+	return &types.MempoolResponse{
+		TransactionIdentifiers: txIDs,
+	}, nil
+}
+
+// MempoolTransaction ...
+func (s *MempoolAPI) MempoolTransaction(
+	ctx context.Context, req *types.MempoolTransactionRequest,
+) (*types.MempoolTransactionResponse, *types.Error) {
+	if err := assertValidNetworkIdentifier(req.NetworkIdentifier, s.hmy.ShardID); err != nil {
+		return nil, err
+	}
+
+	hash := ethCommon.HexToHash(req.TransactionIdentifier.Hash)
+	poolTx := s.hmy.GetPoolTransaction(hash)
+	if poolTx == nil {
+		return nil, &common.TransactionNotFoundError
+	}
+
+	var nilAddress ethCommon.Address
+	senderAddr, _ := poolTx.SenderAddress()
+	estLog := &hmyTypes.Log{
+		Address:     senderAddr,
+		Topics:      []ethCommon.Hash{staking.CollectRewardsTopic},
+		Data:        big.NewInt(0).Bytes(),
+		BlockNumber: s.hmy.CurrentBlock().NumberU64(),
+	}
+
+	estReceipt := &hmyTypes.Receipt{
+		PostState:         []byte{},
+		Status:            hmyTypes.ReceiptStatusSuccessful, // Assume transaction will succeed
+		CumulativeGasUsed: poolTx.Gas(),
+		Bloom:             [256]byte{},
+		Logs:              []*hmyTypes.Log{estLog},
+		TxHash:            poolTx.Hash(),
+		ContractAddress:   nilAddress, // ContractAddress is only for smart contract creation & can not be determined until transaction is finalized
+		GasUsed:           poolTx.Gas(),
+	}
+
+	respTx, err := formatTransaction(poolTx, estReceipt)
+	if err != nil {
+		return nil, err
+	}
+
+	return &types.MempoolTransactionResponse{
+		Transaction: respTx,
+	}, nil
+}