grpc: add shutdown call for external management (#957)

* grpc: add shutdown call for external management

* go mod: tidy

* glorious: suggestion

* Update engine/engine.go

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* Update engine/rpcserver.go

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* Update main.go

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* Update engine/rpcserver.go

Co-authored-by: Scott <gloriousCode@users.noreply.github.com>

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>
Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>
Co-authored-by: Scott <gloriousCode@users.noreply.github.com>

engine/rpcserver.go

@@ -53,22 +53,24 @@ import (
 )
 
 var (
-	errExchangeNotLoaded    = errors.New("exchange is not loaded/doesn't exist")
-	errExchangeNotEnabled   = errors.New("exchange is not enabled")
-	errExchangeBaseNotFound = errors.New("cannot get exchange base")
-	errInvalidArguments     = errors.New("invalid arguments received")
-	errExchangeNameUnset    = errors.New("exchange name unset")
-	errCurrencyPairUnset    = errors.New("currency pair unset")
-	errInvalidTimes         = errors.New("invalid start and end times")
-	errAssetTypeDisabled    = errors.New("asset type is disabled")
-	errAssetTypeUnset       = errors.New("asset type unset")
-	errDispatchSystem       = errors.New("dispatch system offline")
-	errCurrencyNotEnabled   = errors.New("currency not enabled")
-	errCurrencyNotSpecified = errors.New("a currency must be specified")
-	errCurrencyPairInvalid  = errors.New("currency provided is not found in the available pairs list")
-	errNoTrades             = errors.New("no trades returned from supplied params")
-	errNilRequestData       = errors.New("nil request data received, cannot continue")
-	errNoAccountInformation = errors.New("account information does not exist")
+	errExchangeNotLoaded       = errors.New("exchange is not loaded/doesn't exist")
+	errExchangeNotEnabled      = errors.New("exchange is not enabled")
+	errExchangeBaseNotFound    = errors.New("cannot get exchange base")
+	errInvalidArguments        = errors.New("invalid arguments received")
+	errExchangeNameUnset       = errors.New("exchange name unset")
+	errCurrencyPairUnset       = errors.New("currency pair unset")
+	errInvalidTimes            = errors.New("invalid start and end times")
+	errAssetTypeDisabled       = errors.New("asset type is disabled")
+	errAssetTypeUnset          = errors.New("asset type unset")
+	errDispatchSystem          = errors.New("dispatch system offline")
+	errCurrencyNotEnabled      = errors.New("currency not enabled")
+	errCurrencyNotSpecified    = errors.New("a currency must be specified")
+	errCurrencyPairInvalid     = errors.New("currency provided is not found in the available pairs list")
+	errNoTrades                = errors.New("no trades returned from supplied params")
+	errNilRequestData          = errors.New("nil request data received, cannot continue")
+	errNoAccountInformation    = errors.New("account information does not exist")
+	errShutdownNotAllowed      = errors.New("shutting down this bot instance is not allowed via gRPC, please enable by command line flag --grpcshutdown or config.json field grpcAllowBotShutdown")
+	errGRPCShutdownSignalIsNil = errors.New("cannot shutdown, gRPC shutdown channel is nil")
 )
 
 // RPCServer struct
@@ -4561,3 +4563,18 @@ func (s *RPCServer) GetCollateral(ctx context.Context, r *gctrpc.GetCollateralRe
 	}
 	return result, nil
 }
+
+// Shutdown terminates bot session externally
+func (s *RPCServer) Shutdown(_ context.Context, _ *gctrpc.ShutdownRequest) (*gctrpc.ShutdownResponse, error) {
+	if !s.Engine.Settings.EnableGRPCShutdown {
+		return nil, errShutdownNotAllowed
+	}
+
+	if s.Engine.GRPCShutdownSignal == nil {
+		return nil, errGRPCShutdownSignalIsNil
+	}
+
+	s.Engine.GRPCShutdownSignal <- struct{}{}
+	s.Engine.GRPCShutdownSignal = nil
+	return &gctrpc.ShutdownResponse{}, nil
+}