Merge pull request #79 from TGSAI/77_driver_messages

77 driver messages

mdio/dataset.h

@@ -293,8 +293,14 @@ from_zmetadata(const std::string& dataset_path) {
   //  FIXME - enable async
   auto kvs_future = mdio::internal::dataset_kvs_store(dataset_path).result();
 
+  if (!kvs_future.ok()) {
+    return internal::CheckMissingDriverStatus(kvs_future.status());
+  }
   auto kvs_read_result =
       tensorstore::kvstore::Read(kvs_future.value(), ".zmetadata").result();
+  if (!kvs_read_result.ok()) {
+    return internal::CheckMissingDriverStatus(kvs_read_result.status());
+  }
 
   ::nlohmann::json zmetadata;
   try {

mdio/variable.h

@@ -80,6 +80,41 @@ struct SliceDescriptor {
 };
 
 namespace internal {
+
+/**
+ * @brief Checks a status for a missing driver message and returns an MDIO
+ * specific error message.
+ * @param status The status to check
+ * @return A driver specific message if the status is a missing driver message,
+ * otherwise the original status.
+ */
+absl::Status CheckMissingDriverStatus(const absl::Status& status) {
+  std::string error(status.message());
+  if (error.find("Error parsing object member \"driver\"") !=
+      std::string::npos) {
+    if (error.find("is not registered") != std::string::npos) {
+      if (error.find("gcs") != std::string::npos) {
+        return absl::InvalidArgumentError(
+            "A GCS path was detected but the GCS driver was not "
+            "registered.\nPlease ensure that your CMake includes the "
+            "mdio_INTERNAL_GCS_DRIVER_DEPS variable.");
+      } else if (error.find("s3") != std::string::npos) {
+        return absl::InvalidArgumentError(
+            "An S3 path was detected but the S3 driver was not "
+            "registered.\nPlease ensure that your CMake includes the "
+            "mdio_INTERNAL_S3_DRIVER_DEPS variable.");
+      } else {
+        return absl::InvalidArgumentError(
+            "An unexpected driver registration error has occured. Please file "
+            "a bug report with the error message to "
+            "https://github.com/TGSAI/mdio-cpp/issues\n" +
+            error);
+      }
+    }
+  }
+  return status;
+}
+
 /**
  * @brief Validates and processes a JSON specification for a tensorstore
  * variable.
@@ -358,7 +393,7 @@ Future<Variable<T, R, M>> CreateVariable(const nlohmann::json& json_spec,
           tensorstore::ReadyFuture<void> readyFut) {
         auto ready_result = readyFut.result();
         if (!ready_result.ok()) {
-          promise.SetResult(ready_result.status());
+          promise.SetResult(CheckMissingDriverStatus(ready_result.status()));
         } else {
           promise.SetResult(variable_future.result());
         }