fix: add message wrapper to errors and improve resource exhausted err…

…or message by using metadata

internal/momentoerrors/scs_errors.go

@@ -1,6 +1,8 @@
 package momentoerrors
 
 import (
+	"strings"
+
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
@@ -15,7 +17,7 @@ type MomentoSvcErr interface {
 
 // NewMomentoSvcErr returns a new Momento service error.
 func NewMomentoSvcErr(code string, message string, originalErr error) MomentoSvcErr {
-	return newMomentoSvcErr(code, message, originalErr)
+	return newMomentoSvcErr(code, message, originalErr, code)
 }
 
 const (
@@ -37,23 +39,29 @@ const (
 	AuthenticationError = "AuthenticationError"
 	// LimitExceededError occurs when request rate, bandwidth, or object size exceeded the limits for the account.
 	LimitExceededError = "LimitExceededError"
-	// NotFoundError occurs when a cache with specified name doesn't exist.
+	// NotFoundError occurs when a cache with specified name doesn"t exist.
 	//
 	// Deprecated: Use more specific CacheNotFoundError, StoreNotFoundError, or ItemNotFoundError instead.
 	NotFoundError = "NotFoundError"
-	// CacheNotFoundError occurs when a cache with specified name doesn't exist.
+	// CacheNotFoundError occurs when a cache with specified name doesn"t exist.
 	CacheNotFoundError = "NotFoundError"
-	// StoreNotFoundError occurs when a store with specified name doesn't exist.
+	// StoreNotFoundError occurs when a store with specified name doesn"t exist.
 	StoreNotFoundError = "StoreNotFoundError"
-	// ItemNotFoundError occurs when an item with specified key doesn't exist.
+	// ItemNotFoundError occurs when an item with specified key doesn"t exist.
 	ItemNotFoundError = "ItemNotFoundError"
 	// AlreadyExistsError occurs when a cache with specified name already exists.
+	//
+	// Deprecated: Use more specific CacheAlreadyExistsError or StoreAlreadyExistsError instead.
 	AlreadyExistsError = "AlreadyExistsError"
+	// CacheAlreadyExistsError occurs when a cache with specified name already exists.
+	CacheAlreadyExistsError = "AlreadyExistsError"
+	// StoreAlreadyExistsError occurs when a store with specified name already exists.
+	StoreAlreadyExistsError = "StoreAlreadyExistsError"
 	// UnknownServiceError occurs when an unknown error has occurred.
 	UnknownServiceError = "UnknownServiceError"
 	// ServerUnavailableError occurs when the server was unable to handle the request.
 	ServerUnavailableError = "ServerUnavailableError"
-	// FailedPreconditionError occurs when the system is not in a state required for the operation's execution.
+	// FailedPreconditionError occurs when the system is not in a state required for the operation"s execution.
 	FailedPreconditionError = "FailedPreconditionError"
 	// InternalServerErrorMessage is the message for an unexpected error occurring while trying to fulfill the request.
 	InternalServerErrorMessage = "CacheService failed with an internal error"
@@ -63,60 +71,204 @@ const (
 	ConnectionError = "ConnectionError"
 )
 
+const (
+	TopicSubscriptionsLimitExceeded = "Topic subscriptions limit exceeded for this account"
+	OperationsRateLimitExceeded     = "Request rate limit exceeded for this account"
+	ThroughputRateLimitExceeded     = "Bandwidth limit exceeded for this account"
+	RequestSizeLimitExceeded        = "Request size limit exceeded for this account"
+	ItemSizeLimitExceeded           = "Item size limit exceeded for this account"
+	ElementSizeLimitExceeded        = "Element size limit exceeded for this account"
+	UnknownLimitExceeded            = "Limit exceeded for this account"
+)
+
 // ConvertSvcErr converts gRPC error to MomentoSvcErr.
 func ConvertSvcErr(err error, metadata ...metadata.MD) MomentoSvcErr {
 	if grpcStatus, ok := status.FromError(err); ok {
 		switch grpcStatus.Code() {
 		case codes.InvalidArgument:
-			return NewMomentoSvcErr(InvalidArgumentError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				InvalidArgumentError,
+				grpcStatus.Message(),
+				err,
+				"Invalid argument passed to Momento client",
+			)
 		case codes.Unimplemented:
-			return NewMomentoSvcErr(BadRequestError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				BadRequestError,
+				grpcStatus.Message(),
+				err,
+				"The request was invalid; please contact us at [email protected]",
+			)
 		case codes.OutOfRange:
-			return NewMomentoSvcErr(BadRequestError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				BadRequestError,
+				grpcStatus.Message(),
+				err,
+				"The request was invalid; please contact us at [email protected]",
+			)
 		case codes.FailedPrecondition:
-			return NewMomentoSvcErr(FailedPreconditionError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				FailedPreconditionError,
+				grpcStatus.Message(),
+				err,
+				"System is not in a state required for the operation's execution",
+			)
 		case codes.Canceled:
-			return NewMomentoSvcErr(CanceledError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				CanceledError,
+				grpcStatus.Message(),
+				err,
+				"The request was cancelled by the server; please contact us at [email protected]",
+			)
 		case codes.DeadlineExceeded:
-			return NewMomentoSvcErr(TimeoutError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				TimeoutError,
+				grpcStatus.Message(),
+				err,
+				"The client's configured timeout was exceeded; you may need to use a Configuration with more lenient timeouts",
+			)
 		case codes.PermissionDenied:
-			return NewMomentoSvcErr(PermissionError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				PermissionError,
+				grpcStatus.Message(),
+				err,
+				"Insufficient permissions to perform operation",
+			)
 		case codes.Unauthenticated:
-			return NewMomentoSvcErr(AuthenticationError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				AuthenticationError,
+				grpcStatus.Message(),
+				err,
+				"Invalid authentication credentials to connect to Momento service",
+			)
 		case codes.ResourceExhausted:
-			return NewMomentoSvcErr(LimitExceededError, grpcStatus.Message(), err)
+			// By default, use the generic limit exceeded message wrapper.
+			messageWrapper := UnknownLimitExceeded
+
+			// If available, use metadata to determine cause of resource exhausted error.
+			if len(metadata) > 1 {
+				errData, ok := metadata[1]["err"]
+				if ok && errData[0] != "" {
+					switch errData[0] {
+					case "topic_subscriptions_limit_exceeded":
+						messageWrapper = TopicSubscriptionsLimitExceeded
+					case "operations_rate_limit_exceeded":
+						messageWrapper = OperationsRateLimitExceeded
+					case "throughput_rate_limit_exceeded":
+						messageWrapper = ThroughputRateLimitExceeded
+					case "request_size_limit_exceeded":
+						messageWrapper = RequestSizeLimitExceeded
+					case "item_size_limit_exceeded":
+						messageWrapper = ItemSizeLimitExceeded
+					case "element_size_limit_exceeded":
+						messageWrapper = ElementSizeLimitExceeded
+					}
+				} else {
+					// If err metadata is not available, try string matching on the
+					// error details to return the most specific message wrapper.
+					lowerCasedMessage := strings.ToLower(grpcStatus.Message())
+					if strings.Contains(lowerCasedMessage, "subscribers") {
+						messageWrapper = TopicSubscriptionsLimitExceeded
+					} else if strings.Contains(lowerCasedMessage, "operations") {
+						messageWrapper = OperationsRateLimitExceeded
+					} else if strings.Contains(lowerCasedMessage, "throughput") {
+						messageWrapper = ThroughputRateLimitExceeded
+					} else if strings.Contains(lowerCasedMessage, "request limit") {
+						messageWrapper = RequestSizeLimitExceeded
+					} else if strings.Contains(lowerCasedMessage, "item size") {
+						messageWrapper = ItemSizeLimitExceeded
+					} else if strings.Contains(lowerCasedMessage, "element size") {
+						messageWrapper = ElementSizeLimitExceeded
+					}
+				}
+			}
+			return newMomentoSvcErr(LimitExceededError, grpcStatus.Message(), err, messageWrapper)
 		case codes.NotFound:
+			cacheMessageWrapper := "A cache with the specified name does not exist.  To resolve this error, make sure you have created the cache before attempting to use it"
+			storeMessageWrapper := "A store with the specified name does not exist.  To resolve this error, make sure you have created the store before attempting to use it"
 			// Use metadata to determine cause of not found error
 			if len(metadata) > 1 {
 				errData, ok := metadata[1]["err"]
 				// In the absence of error metadata, return CacheNotFoundError.
-				// This is currently re-mapped to a StoreNotFoundError in the PreviewStorageClient's
+				// This is currently re-mapped to a StoreNotFoundError in the PreviewStorageClient"s
 				// DeleteStore method.
 				if !ok {
-					return NewMomentoSvcErr(CacheNotFoundError, grpcStatus.Message(), err)
+					return newMomentoSvcErr(CacheNotFoundError, grpcStatus.Message(), err, cacheMessageWrapper)
 				}
 				errCause := errData[0]
 				if errCause == "item_not_found" {
-					return NewMomentoSvcErr(ItemNotFoundError, grpcStatus.Message(), err)
+					return newMomentoSvcErr(
+						ItemNotFoundError,
+						grpcStatus.Message(),
+						err,
+						"An item with the specified key does not exist",
+					)
 				} else if errCause == "store_not_found" {
-					return NewMomentoSvcErr(StoreNotFoundError, grpcStatus.Message(), err)
+					return newMomentoSvcErr(StoreNotFoundError, grpcStatus.Message(), err, storeMessageWrapper)
 				}
 			}
-			return NewMomentoSvcErr(CacheNotFoundError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(CacheNotFoundError, grpcStatus.Message(), err, cacheMessageWrapper)
 		case codes.AlreadyExists:
-			return NewMomentoSvcErr(AlreadyExistsError, grpcStatus.Message(), err)
+			cacheMessageWrapper := "A cache with the specified name already exists.  To resolve this error, either delete the existing cache and make a new one, or use a different name"
+			storeMessageWrapper := "A store with the specified name already exists.  To resolve this error, either delete the existing store and make a new one, or use a different name"
+			if len(metadata) > 1 {
+				errData, ok := metadata[1]["err"]
+				// In the absence of error metadata, return CacheAlreadyExistsError.
+				if !ok {
+					return newMomentoSvcErr(CacheAlreadyExistsError, grpcStatus.Message(), err, cacheMessageWrapper)
+				}
+				errCause := errData[0]
+				switch errCause {
+				case "store_already_exists":
+					return newMomentoSvcErr(StoreAlreadyExistsError, grpcStatus.Message(), err, storeMessageWrapper)
+				default:
+					return newMomentoSvcErr(CacheAlreadyExistsError, grpcStatus.Message(), err, cacheMessageWrapper)
+				}
+			}
+			// If no metadata is available, return CacheAlreadyExistsError by default.
+			return newMomentoSvcErr(CacheAlreadyExistsError, grpcStatus.Message(), err, cacheMessageWrapper)
 		case codes.Unknown:
-			return NewMomentoSvcErr(UnknownServiceError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				UnknownServiceError,
+				grpcStatus.Message(),
+				err,
+				"Service returned an unknown response; please contact us at [email protected]",
+			)
 		case codes.Aborted:
-			return NewMomentoSvcErr(InternalServerError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				InternalServerError,
+				grpcStatus.Message(),
+				err,
+				"Unexpected error encountered while trying to fulfill the request; please contact us at [email protected]",
+			)
 		case codes.Internal:
-			return NewMomentoSvcErr(InternalServerError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				InternalServerError,
+				grpcStatus.Message(),
+				err,
+				"Unexpected error encountered while trying to fulfill the request; please contact us at [email protected]",
+			)
 		case codes.Unavailable:
-			return NewMomentoSvcErr(ServerUnavailableError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				ServerUnavailableError,
+				grpcStatus.Message(),
+				err,
+				"The server was unable to handle the request; consider retrying.  If the error persists, please contact us at [email protected]",
+			)
 		case codes.DataLoss:
-			return NewMomentoSvcErr(InternalServerError, grpcStatus.Message(), err)
+			return newMomentoSvcErr(
+				InternalServerError,
+				grpcStatus.Message(),
+				err,
+				"Unexpected error encountered while trying to fulfill the request; please contact us at [email protected]",
+			)
 		default:
-			return NewMomentoSvcErr(UnknownServiceError, InternalServerErrorMessage, err)
+			return newMomentoSvcErr(
+				UnknownServiceError,
+				InternalServerErrorMessage,
+				err,
+				"Service returned an unknown response; please contact us at [email protected]",
+			)
 		}
 	}
 	return NewMomentoSvcErr(ClientSdkError, ClientSdkErrorMessage, err)

internal/momentoerrors/types.go

@@ -3,16 +3,18 @@ package momentoerrors
 import "fmt"
 
 type momentoSvcError struct {
-	code        string
-	message     string
-	originalErr error
+	code           string
+	message        string
+	originalErr    error
+	messageWrapper string
 }
 
-func newMomentoSvcErr(code string, message string, originalErr error) *momentoSvcError {
+func newMomentoSvcErr(code string, message string, originalErr error, messageWrapper string) *momentoSvcError {
 	return &momentoSvcError{
 		code,
 		message,
 		originalErr,
+		messageWrapper,
 	}
 }
 
@@ -21,7 +23,10 @@ func (err momentoSvcError) Code() string {
 }
 
 func (err momentoSvcError) Message() string {
-	return err.message
+	if err.messageWrapper == "" {
+		return err.message
+	}
+	return err.messageWrapper + ": " + err.message
 }
 
 func (err momentoSvcError) OriginalErr() error {