[GitHub] [nifi-minifi-cpp] szaszm commented on a change in pull request #1221: MINIFICPP-1630 Create FetchAzureDataLakeStorage processor

[GitBox <gi...@apache.org>]

szaszm commented on a change in pull request #1221:
URL: https://github.com/apache/nifi-minifi-cpp/pull/1221#discussion_r782222859



##########
File path: extensions/azure/processors/FetchAzureDataLakeStorage.cpp
##########
@@ -0,0 +1,125 @@
+/**
+ * @file FetchAzureDataLakeStorage.cpp
+ * FetchAzureDataLakeStorage class implementation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "FetchAzureDataLakeStorage.h"
+
+#include "core/Resource.h"
+
+namespace org::apache::nifi::minifi::azure::processors {
+
+const core::Property FetchAzureDataLakeStorage::RangeStart(
+    core::PropertyBuilder::createProperty("Range Start")
+      ->withDescription("The byte position at which to start reading from the object. An empty value or a value of zero will start reading at the beginning of the object.")
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Property FetchAzureDataLakeStorage::RangeLength(
+    core::PropertyBuilder::createProperty("Range Length")
+      ->withDescription("The number of bytes to download from the object, starting from the Range Start. "
+                        "An empty value or a value that extends beyond the end of the object will read to the end of the object.")
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Property FetchAzureDataLakeStorage::NumberOfRetries(
+    core::PropertyBuilder::createProperty("Number of Retries")
+      ->withDescription("The number of automatic retries to perform if the download fails.")
+      ->withDefaultValue<uint64_t>(0)
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Relationship FetchAzureDataLakeStorage::Success("success", "Files that have been successfully fetched from Azure storage are transferred to this relationship");
+const core::Relationship FetchAzureDataLakeStorage::Failure("failure", "In case of fetch failure flowfiles are transferred to this relationship");
+
+void FetchAzureDataLakeStorage::initialize() {
+  // Add new supported properties
+  setSupportedProperties({
+    AzureStorageCredentialsService,
+    FilesystemName,
+    DirectoryName,
+    FileName,
+    RangeStart,
+    RangeLength,
+    NumberOfRetries
+  });
+  // Set the supported relationships
+  setSupportedRelationships({
+    Success,
+    Failure
+  });
+}
+
+std::optional<storage::FetchAzureDataLakeStorageParameters> FetchAzureDataLakeStorage::buildFetchParameters(
+    const std::shared_ptr<core::ProcessContext>& context, const std::shared_ptr<core::FlowFile>& flow_file) {
+  storage::FetchAzureDataLakeStorageParameters params;
+  if (!setCommonParameters(params, *context, flow_file)) {
+    return std::nullopt;
+  }
+
+  std::string value;
+  if (context->getProperty(RangeStart, value, flow_file)) {
+    params.range_start = std::stoull(value);
+    logger_->log_debug("Range Start property set to %llu", *params.range_start);
+  }
+
+  if (context->getProperty(RangeLength, value, flow_file)) {
+    params.range_length = std::stoull(value);
+    logger_->log_debug("Range Length property set to %llu", *params.range_length);
+  }
+
+  if (context->getProperty(NumberOfRetries, value, flow_file)) {
+    params.number_of_retries = std::stoull(value);
+    logger_->log_debug("Number Of Retries property set to %llu", *params.number_of_retries);
+  }
+
+  return params;
+}
+
+void FetchAzureDataLakeStorage::onTrigger(const std::shared_ptr<core::ProcessContext>& context, const std::shared_ptr<core::ProcessSession>& session) {

Review comment:
       It would be nice to declare the preconditions that `context` and `session` must be valid.
   ```suggestion
   void FetchAzureDataLakeStorage::onTrigger(const std::shared_ptr<core::ProcessContext>& context, const std::shared_ptr<core::ProcessSession>& session) {
     gsl_Expects(context && session);
   ```

##########
File path: extensions/azure/storage/AzureDataLakeStorage.cpp
##########
@@ -61,4 +61,29 @@ bool AzureDataLakeStorage::deleteFile(const storage::DeleteAzureDataLakeStorageP
   }
 }
 
+std::optional<uint64_t> AzureDataLakeStorage::fetchFile(const FetchAzureDataLakeStorageParameters& params, io::BaseStream& stream) {
+  try {
+    auto fetch_res = data_lake_storage_client_->fetchFile(params);
+
+    std::array<uint8_t, 4096> buffer;
+    size_t write_size = 0;
+    if (fetch_res.FileSize < 0) return 0;
+    while (write_size < gsl::narrow<uint64_t>(fetch_res.FileSize)) {
+      const auto next_write_size = (std::min)(gsl::narrow<size_t>(fetch_res.FileSize) - write_size, buffer.size());
+      if (!fetch_res.Body->Read(buffer.data(), gsl::narrow<std::streamsize>(next_write_size))) {
+        return -1;
+      }
+      const auto ret = stream.write(buffer.data(), next_write_size);
+      if (io::isError(ret)) {
+        return -1;
+      }
+      write_size += next_write_size;
+    }

Review comment:
       Not sure if it's worth the extra effort, but if you could wrap the download result in an `InputStream`, then you could reuse `internal::pipe` (which has similar code to this function) or just return the stream directly.]
   It would also probably be easier to mock `fetchFile`.

##########
File path: extensions/azure/processors/FetchAzureDataLakeStorage.cpp
##########
@@ -0,0 +1,125 @@
+/**
+ * @file FetchAzureDataLakeStorage.cpp
+ * FetchAzureDataLakeStorage class implementation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "FetchAzureDataLakeStorage.h"
+
+#include "core/Resource.h"
+
+namespace org::apache::nifi::minifi::azure::processors {
+
+const core::Property FetchAzureDataLakeStorage::RangeStart(
+    core::PropertyBuilder::createProperty("Range Start")
+      ->withDescription("The byte position at which to start reading from the object. An empty value or a value of zero will start reading at the beginning of the object.")
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Property FetchAzureDataLakeStorage::RangeLength(
+    core::PropertyBuilder::createProperty("Range Length")
+      ->withDescription("The number of bytes to download from the object, starting from the Range Start. "
+                        "An empty value or a value that extends beyond the end of the object will read to the end of the object.")
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Property FetchAzureDataLakeStorage::NumberOfRetries(
+    core::PropertyBuilder::createProperty("Number of Retries")
+      ->withDescription("The number of automatic retries to perform if the download fails.")
+      ->withDefaultValue<uint64_t>(0)
+      ->supportsExpressionLanguage(true)
+      ->build());
+
+const core::Relationship FetchAzureDataLakeStorage::Success("success", "Files that have been successfully fetched from Azure storage are transferred to this relationship");
+const core::Relationship FetchAzureDataLakeStorage::Failure("failure", "In case of fetch failure flowfiles are transferred to this relationship");
+
+void FetchAzureDataLakeStorage::initialize() {
+  // Add new supported properties
+  setSupportedProperties({
+    AzureStorageCredentialsService,
+    FilesystemName,
+    DirectoryName,
+    FileName,
+    RangeStart,
+    RangeLength,
+    NumberOfRetries
+  });
+  // Set the supported relationships
+  setSupportedRelationships({
+    Success,
+    Failure
+  });
+}
+
+std::optional<storage::FetchAzureDataLakeStorageParameters> FetchAzureDataLakeStorage::buildFetchParameters(
+    const std::shared_ptr<core::ProcessContext>& context, const std::shared_ptr<core::FlowFile>& flow_file) {
+  storage::FetchAzureDataLakeStorageParameters params;

Review comment:
       There is no reason for this function to necessitate shared ownership. The first parameter should preferably be of type `const core::ProcessContext&`. The second one needs to be a `shared_ptr` due to `getProperty` (also unnecessarily) requiring a `shared_ptr` parameter.




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