enhance: use milvus-storage internal C++ Reader API for Loon FFI (#45897)

This PR refactors the Loon FFI reader implementation to use
milvus-storage's internal C++ Reader API directly instead of the
external FFI interface.

Key changes:
- Replace external FFI calls (get_record_batch_reader, reader_destroy)
with direct C++ Reader API calls
- Add GetLoonReader() helper function to create Reader instances using
milvus-storage::api::Reader::create()
- Use MakeInternalPropertiesFromStorageConfig() instead of
MakePropertiesFromStorageConfig() to get internal properties
- Update NewPackedFFIReaderWithManifest() to deserialize column groups
from JSON manifest content directly
- Simplify GetFFIReaderStream() to use Reader::get_record_batch_reader()
and arrow::ExportRecordBatchReader() for Arrow stream export
- Change CFFIPackedReader typedef from ReaderHandle to void* for
flexibility
- Update milvus-storage dependency version to ba7df7b

This change improves code maintainability by using the native C++ API
directly and eliminates the overhead of going through the external FFI
layer.

issue: #44956

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

internal/core/src/storage/loon_ffi/ffi_reader_c.cpp

@@ -17,6 +17,7 @@
 #include "storage/loon_ffi/ffi_reader_c.h"
 #include "common/common_type_c.h"
 #include "milvus-storage/ffi_c.h"
+#include "milvus-storage/reader.h"
 #include "storage/loon_ffi/util.h"
 #include "monitor/scope_metric.h"
 
@@ -46,6 +47,24 @@ createFFIReader(char* manifest,
     return reader_handler;
 }
 
+std::unique_ptr<milvus_storage::api::Reader>
+GetLoonReader(
+    std::shared_ptr<milvus_storage::api::ColumnGroups> column_groups,
+    struct ArrowSchema* schema,
+    char** needed_columns,
+    int64_t needed_columns_size,
+    const std::shared_ptr<milvus_storage::api::Properties>& properties) {
+    auto result = arrow::ImportSchema(schema);
+    AssertInfo(result.ok(), "Import arrow schema failed");
+    auto arrow_schema = result.ValueOrDie();
+    return milvus_storage::api::Reader::create(
+        column_groups,
+        arrow_schema,
+        std::make_shared<std::vector<std::string>>(
+            needed_columns, needed_columns + needed_columns_size),
+        *properties);
+}
+
 CStatus
 NewPackedFFIReader(const char* manifest_path,
                    struct ArrowSchema* schema,
@@ -57,16 +76,20 @@ NewPackedFFIReader(const char* manifest_path,
     SCOPE_CGO_CALL_METRIC();
 
     try {
-        auto properties = MakePropertiesFromStorageConfig(c_storage_config);
-
+        auto properties =
+            MakeInternalPropertiesFromStorageConfig(c_storage_config);
         AssertInfo(properties != nullptr, "properties is nullptr");
 
-        // Use manifest_path if provided
-        char* manifest =
-            manifest_path ? const_cast<char*>(manifest_path) : nullptr;
-        ReaderHandle reader_handle = createFFIReader(
-            manifest, schema, needed_columns, needed_columns_size, properties);
-        *c_packed_reader = reader_handle;
+        auto column_groups = GetColumnGroups(manifest_path, properties);
+        AssertInfo(column_groups != nullptr, "column groups is nullptr");
+
+        auto reader = GetLoonReader(column_groups,
+                                    schema,
+                                    needed_columns,
+                                    needed_columns_size,
+                                    properties);
+
+        *c_packed_reader = static_cast<CFFIPackedReader>(reader.release());
         return milvus::SuccessCStatus();
     } catch (std::exception& e) {
         return milvus::FailureCStatus(&e);
@@ -78,22 +101,28 @@ NewPackedFFIReaderWithManifest(const char* manifest_content,
                                struct ArrowSchema* schema,
                                char** needed_columns,
                                int64_t needed_columns_size,
-                               CFFIPackedReader* c_packed_reader,
+                               CFFIPackedReader* c_loon_reader,
                                CStorageConfig c_storage_config,
                                CPluginContext* c_plugin_context) {
     SCOPE_CGO_CALL_METRIC();
 
     try {
-        auto properties = MakePropertiesFromStorageConfig(c_storage_config);
+        auto properties =
+            MakeInternalPropertiesFromStorageConfig(c_storage_config);
+        // Parse the column groups, the column groups is a JSON string
+        auto cpp_column_groups =
+            std::make_shared<milvus_storage::api::ColumnGroups>();
+        auto des_result =
+            cpp_column_groups->deserialize(std::string_view(manifest_content));
+        AssertInfo(des_result.ok(), "failed to deserialize column groups");
 
-        AssertInfo(properties != nullptr, "properties is nullptr");
+        auto reader = GetLoonReader(cpp_column_groups,
+                                    schema,
+                                    needed_columns,
+                                    needed_columns_size,
+                                    properties);
 
-        // Use manifest_content as the manifest parameter
-        char* manifest =
-            manifest_content ? const_cast<char*>(manifest_content) : nullptr;
-        ReaderHandle reader_handle = createFFIReader(
-            manifest, schema, needed_columns, needed_columns_size, properties);
-        *c_packed_reader = reader_handle;
+        *c_loon_reader = static_cast<CFFIPackedReader>(reader.release());
         return milvus::SuccessCStatus();
     } catch (std::exception& e) {
         return milvus::FailureCStatus(&e);
@@ -107,23 +136,23 @@ GetFFIReaderStream(CFFIPackedReader c_packed_reader,
     SCOPE_CGO_CALL_METRIC();
 
     try {
-        auto reader_handle = static_cast<ReaderHandle>(c_packed_reader);
+        auto reader =
+            static_cast<milvus_storage::api::Reader*>(c_packed_reader);
 
-        // Default parameters for get_record_batch_reader
-        const char* predicate = nullptr;  // No filtering
-        FFIResult result =
-            get_record_batch_reader(reader_handle, predicate, out_stream);
+        // FFIResult result =
+        //     get_record_batch_reader(reader_handle, predicate, out_stream);
+        auto result = reader->get_record_batch_reader();
+        AssertInfo(result.ok(),
+                   "failed to get record batch reader, {}",
+                   result.status().ToString());
 
-        if (!IsSuccess(&result)) {
-            auto message = GetErrorMessage(&result);
-            std::string error_msg =
-                message ? message : "Failed to get record batch reader";
-            FreeFFIResult(&result);
-            return milvus::FailureCStatus(milvus::ErrorCode::FileReadFailed,
-                                          error_msg);
-        }
+        auto array_stream = result.ValueOrDie();
+        arrow::Status status =
+            arrow::ExportRecordBatchReader(array_stream, out_stream);
+        AssertInfo(status.ok(),
+                   "failed to export record batch reader, {}",
+                   status.ToString());
 
-        FreeFFIResult(&result);
         return milvus::SuccessCStatus();
     } catch (std::exception& e) {
         return milvus::FailureCStatus(&e);
@@ -135,10 +164,9 @@ CloseFFIReader(CFFIPackedReader c_packed_reader) {
     SCOPE_CGO_CALL_METRIC();
 
     try {
-        auto reader_handle = static_cast<ReaderHandle>(c_packed_reader);
-        if (reader_handle != 0) {
-            reader_destroy(reader_handle);
-        }
+        auto reader =
+            static_cast<milvus_storage::api::Reader*>(c_packed_reader);
+        delete reader;
         return milvus::SuccessCStatus();
     } catch (std::exception& e) {
         return milvus::FailureCStatus(&e);

internal/core/src/storage/loon_ffi/ffi_reader_c.h

@@ -30,7 +30,7 @@ extern "C" {
  * from storage in Milvus. The reader supports Arrow-based data access
  * through the FFI (Foreign Function Interface) layer.
  */
-typedef ReaderHandle CFFIPackedReader;
+typedef void* CFFIPackedReader;
 
 /**
  * @brief Creates a new packed FFI reader from a manifest file path.
@@ -109,7 +109,7 @@ NewPackedFFIReaderWithManifest(const char* manifest_content,
                                struct ArrowSchema* schema,
                                char** needed_columns,
                                int64_t needed_columns_size,
-                               CFFIPackedReader* c_packed_reader,
+                               CFFIPackedReader* c_loon_reader,
                                CStorageConfig c_storage_config,
                                CPluginContext* c_plugin_context);
 

internal/storagev2/packed/packed_reader_ffi.go

@@ -163,13 +163,8 @@ func (r *FFIPackedReader) Close() error {
 		r.recordReader = nil
 	}
 
-	if r.cPackedReader != 0 {
-		status := C.CloseFFIReader(r.cPackedReader)
-		r.cPackedReader = 0
-		return ConsumeCStatusIntoError(&status)
-	}
-
-	return nil
+	status := C.CloseFFIReader(r.cPackedReader)
+	return ConsumeCStatusIntoError(&status)
 }
 
 // Schema returns the schema of the reader