enhance: [2.6] always use buffered io for high load priority (#45958)

issue: #43040
pr: #45900

Signed-off-by: Shawn Wang <shawn.wang@zilliz.com>

internal/core/src/common/ChunkTarget.h

@@ -53,9 +53,12 @@ class ChunkTarget {
 
 class MmapChunkTarget : public ChunkTarget {
  public:
-    explicit MmapChunkTarget(std::string file_path, size_t cap)
+    explicit MmapChunkTarget(std::string file_path,
+                             size_t cap,
+                             storage::io::Priority io_prio)
         : file_path_(std::move(file_path)), cap_(cap) {
-        file_writer_ = std::make_unique<storage::FileWriter>(file_path_);
+        file_writer_ =
+            std::make_unique<storage::FileWriter>(file_path_, io_prio);
     }
 
     void

internal/core/src/common/ChunkWriter.cpp

@@ -23,6 +23,7 @@
 #include "common/EasyAssert.h"
 #include "common/Types.h"
 #include "simdjson/padded_string.h"
+#include "storage/FileWriter.h"
 
 namespace milvus {
 
@@ -712,7 +713,8 @@ make_chunk(const FieldMeta& field_meta,
 std::unique_ptr<Chunk>
 create_chunk(const FieldMeta& field_meta,
              const arrow::ArrayVector& array_vec,
-             const std::string& file_path) {
+             const std::string& file_path,
+             proto::common::LoadPriority load_priority) {
     auto cw = create_chunk_writer(field_meta);
     auto [size, row_nums] = cw->calculate_size(array_vec);
     size_t aligned_size = (size + ChunkTarget::ALIGNED_SIZE - 1) &
@@ -721,7 +723,9 @@ create_chunk(const FieldMeta& field_meta,
     if (file_path.empty()) {
         target = std::make_shared<MemChunkTarget>(aligned_size);
     } else {
-        target = std::make_shared<MmapChunkTarget>(file_path, aligned_size);
+        auto io_prio = storage::io::GetPriorityFromLoadPriority(load_priority);
+        target =
+            std::make_shared<MmapChunkTarget>(file_path, aligned_size, io_prio);
     }
     cw->write_to_target(array_vec, target);
     auto data = target->release();
@@ -740,7 +744,8 @@ std::unordered_map<FieldId, std::shared_ptr<Chunk>>
 create_group_chunk(const std::vector<FieldId>& field_ids,
                    const std::vector<FieldMeta>& field_metas,
                    const std::vector<arrow::ArrayVector>& array_vec,
-                   const std::string& file_path) {
+                   const std::string& file_path,
+                   proto::common::LoadPriority load_priority) {
     std::vector<std::shared_ptr<ChunkWriterBase>> cws;
     cws.reserve(field_ids.size());
     size_t total_aligned_size = 0, final_row_nums = 0;
@@ -776,8 +781,10 @@ create_group_chunk(const std::vector<FieldId>& field_ids,
     if (file_path.empty()) {
         target = std::make_shared<MemChunkTarget>(total_aligned_size);
     } else {
-        target =
+        target = std::make_shared<MmapChunkTarget>(
-            std::make_shared<MmapChunkTarget>(file_path, total_aligned_size);
+            file_path,
+            total_aligned_size,
+            storage::io::GetPriorityFromLoadPriority(load_priority));
     }
     for (size_t i = 0; i < field_ids.size(); i++) {
         auto start_off = target->tell();

internal/core/src/common/ChunkWriter.h

@@ -242,13 +242,17 @@ class SparseFloatVectorChunkWriter : public ChunkWriterBase {
 std::unique_ptr<Chunk>
 create_chunk(const FieldMeta& field_meta,
              const arrow::ArrayVector& array_vec,
-             const std::string& file_path = "");
+             const std::string& file_path = "",
+             proto::common::LoadPriority load_priority =
+                 proto::common::LoadPriority::HIGH);
 
 std::unordered_map<FieldId, std::shared_ptr<Chunk>>
 create_group_chunk(const std::vector<FieldId>& field_ids,
                    const std::vector<FieldMeta>& field_metas,
                    const std::vector<arrow::ArrayVector>& array_vec,
-                   const std::string& file_path = "");
+                   const std::string& file_path = "",
+                   proto::common::LoadPriority load_priority =
+                       proto::common::LoadPriority::HIGH);
 
 arrow::ArrayVector
 read_single_column_batches(std::shared_ptr<arrow::RecordBatchReader> reader);

internal/core/src/segcore/ChunkedSegmentSealedImpl.cpp

@@ -424,7 +424,8 @@ ChunkedSegmentSealedImpl::load_field_data_internal(
             LOG_INFO("segment {} submits load field {} task to thread pool",
                      this->get_segment_id(),
                      field_id.get());
-            load_system_field_internal(field_id, field_data_info);
+            load_system_field_internal(
+                field_id, field_data_info, load_info.load_priority);
             LOG_INFO("segment {} loads system field {} mmap false done",
                      this->get_segment_id(),
                      field_id.get());
@@ -463,8 +464,10 @@ ChunkedSegmentSealedImpl::load_field_data_internal(
 }
 
 void
-ChunkedSegmentSealedImpl::load_system_field_internal(FieldId field_id,
+ChunkedSegmentSealedImpl::load_system_field_internal(
-                                                     FieldDataInfo& data) {
+    FieldId field_id,
+    FieldDataInfo& data,
+    proto::common::LoadPriority load_priority) {
     SCOPE_CGO_CALL_METRIC();
 
     auto num_rows = data.row_count;

internal/core/src/segcore/ChunkedSegmentSealedImpl.h

@@ -39,6 +39,8 @@
 #include "folly/concurrency/ConcurrentHashMap.h"
 #include "index/json_stats/JsonKeyStats.h"
 #include "pb/index_cgo_msg.pb.h"
+#include "pb/common.pb.h"
+#include "milvus-storage/reader.h"
 
 namespace milvus::segcore {
 
@@ -383,7 +385,10 @@ class ChunkedSegmentSealedImpl : public SegmentSealed {
 
  private:
     void
-    load_system_field_internal(FieldId field_id, FieldDataInfo& data);
+    load_system_field_internal(
+        FieldId field_id,
+        FieldDataInfo& data,
+        milvus::proto::common::LoadPriority load_priority);
 
     template <typename PK>
     void

internal/core/src/segcore/storagev1translator/ChunkTranslator.cpp

@@ -201,7 +201,8 @@ ChunkTranslator::get_cells(
             AssertInfo(popped, "failed to pop arrow reader from channel");
             arrow::ArrayVector array_vec =
                 read_single_column_batches(r->reader);
-            chunk = create_chunk(field_meta_, array_vec, filepath.string());
+            chunk = create_chunk(
+                field_meta_, array_vec, filepath.string(), load_priority_);
         }
         cells.emplace_back(cid, std::move(chunk));
     }

internal/core/src/storage/FileWriter.cpp

@@ -25,7 +25,10 @@ FileWriter::FileWriter(std::string filename, io::Priority priority)
     : filename_(std::move(filename)),
       priority_(priority),
       rate_limiter_(io::WriteRateLimiter::GetInstance()) {
-    auto mode = GetMode();
+    // high priority always use buffered mode, otherwise use the global mode
+    auto mode =
+        priority_ == io::Priority::HIGH ? WriteMode::BUFFERED : GetMode();
+
     use_direct_io_ = mode == WriteMode::DIRECT;
     use_writer_pool_ = FileWriteWorkerPool::GetInstance().HasPool();