issue #324: DescribeData API and implementation stub (#329)

cloud/filestore/libs/storage/api/tablet.h

@@ -22,6 +22,7 @@ namespace NCloud::NFileStore::NStorage {
     xxx(GetFileSystemConfig,        __VA_ARGS__)                               \
     xxx(GetStorageConfigFields,     __VA_ARGS__)                               \
     xxx(ChangeStorageConfig,        __VA_ARGS__)                               \
+    xxx(DescribeData,               __VA_ARGS__)                               \
 // FILESTORE_TABLET_REQUESTS
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -57,6 +58,9 @@ struct TEvIndexTablet
         EvChangeStorageConfigRequest = EvBegin + 13,
         EvChangeStorageConfigResponse,
 
+        EvDescribeDataRequest = EvBegin + 15,
+        EvDescribeDataResponse,
+
         EvEnd
     };
 

cloud/filestore/libs/storage/tablet/tablet_actor_readdata.cpp

@@ -390,7 +390,8 @@ STFUNC(TReadDataActor::StateWork)
 
 ////////////////////////////////////////////////////////////////////////////////
 
-NProto::TError ValidateRequest(const NProto::TReadDataRequest& request, ui32 blockSize)
+template <typename TReadRequest>
+NProto::TError ValidateRequest(const TReadRequest& request, ui32 blockSize)
 {
     const TByteRange range(
         request.GetOffset(),
@@ -447,7 +448,8 @@ void TIndexTabletActor::HandleReadData(
         msg->Record,
         byteRange,
         alignedByteRange,
-        std::move(blockBuffer));
+        std::move(blockBuffer),
+        false /* describeOnly */);
 }
 
 void TIndexTabletActor::HandleReadDataCompleted(
@@ -463,6 +465,45 @@ void TIndexTabletActor::HandleReadDataCompleted(
 
 ////////////////////////////////////////////////////////////////////////////////
 
+void TIndexTabletActor::HandleDescribeData(
+    const TEvIndexTablet::TEvDescribeDataRequest::TPtr& ev,
+    const TActorContext& ctx)
+{
+    auto validator = [&] (const NProtoPrivate::TDescribeDataRequest& request) {
+        return ValidateRequest(request, GetBlockSize());
+    };
+
+    if (!AcceptRequest<TEvIndexTablet::TDescribeDataMethod>(ev, ctx, validator)) {
+        return;
+    }
+
+    auto* msg = ev->Get();
+    const TByteRange byteRange(
+        msg->Record.GetOffset(),
+        msg->Record.GetLength(),
+        GetBlockSize()
+    );
+
+    auto requestInfo = CreateRequestInfo(
+        ev->Sender,
+        ev->Cookie,
+        msg->CallContext);
+
+    TByteRange alignedByteRange = byteRange.AlignedSuperRange();
+    auto blockBuffer = CreateBlockBuffer(alignedByteRange);
+
+    ExecuteTx<TReadData>(
+        ctx,
+        std::move(requestInfo),
+        msg->Record,
+        byteRange,
+        alignedByteRange,
+        std::move(blockBuffer),
+        true /* describeOnly */);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 bool TIndexTabletActor::PrepareTx_ReadData(
     const TActorContext& ctx,
     TTransactionContext& tx,
@@ -584,19 +625,54 @@ void TIndexTabletActor::CompleteTx_ReadData(
     const TActorContext& ctx,
     TTxIndexTablet::TReadData& args)
 {
-    if (FAILED(args.Error.GetCode())) {
-        auto response = std::make_unique<TEvService::TEvReadDataResponse>(args.Error);
-        CompleteResponse<TEvService::TReadDataMethod>(
+    if (args.DescribeOnly && !HasError(args.Error)) {
+        auto response =
+            std::make_unique<TEvIndexTablet::TEvDescribeDataResponse>();
+        auto& record = response->Record;
+
+        // TODO: fill record.{BlobPieces,FreshDataRanges}
+        Y_UNUSED(record);
+
+        CompleteResponse<TEvIndexTablet::TDescribeDataMethod>(
             response->Record,
             args.RequestInfo->CallContext,
             ctx);
 
         NCloud::Reply(ctx, *args.RequestInfo, std::move(response));
+
+        return;
+    }
+
+    if (HasError(args.Error)) {
+        if (args.DescribeOnly) {
+            auto response =
+                std::make_unique<TEvIndexTablet::TEvDescribeDataResponse>(args.Error);
+            CompleteResponse<TEvIndexTablet::TDescribeDataMethod>(
+                response->Record,
+                args.RequestInfo->CallContext,
+                ctx);
+
+            NCloud::Reply(ctx, *args.RequestInfo, std::move(response));
+        } else {
+            auto response =
+                std::make_unique<TEvService::TEvReadDataResponse>(args.Error);
+            CompleteResponse<TEvService::TReadDataMethod>(
+                response->Record,
+                args.RequestInfo->CallContext,
+                ctx);
+
+            NCloud::Reply(ctx, *args.RequestInfo, std::move(response));
+        }
+
         return;
     }
 
     if (!ShouldReadBlobs(args.Blocks)) {
-        ApplyBytes(LogTag, args.AlignedByteRange, std::move(args.Bytes), *args.Buffer);
+        ApplyBytes(
+            LogTag,
+            args.AlignedByteRange,
+            std::move(args.Bytes),
+            *args.Buffer);
 
         auto response = std::make_unique<TEvService::TEvReadDataResponse>();
         CopyFileData(

cloud/filestore/libs/storage/tablet/tablet_actor_request.cpp

@@ -112,6 +112,7 @@ template void TIndexTabletActor::CompleteResponse<ns::T##name##Method>(
 // FILESTORE_IMPL_VALIDATE
 
 FILESTORE_SERVICE(FILESTORE_GENERATE_IMPL, TEvService)
+FILESTORE_GENERATE_IMPL(DescribeData, TEvIndexTablet)
 
 #undef FILESTORE_GENERATE_IMPL
 

cloud/filestore/libs/storage/tablet/tablet_tx.h

@@ -1123,6 +1123,7 @@ struct TTxIndexTablet
         const TByteRange OriginByteRange;
         const TByteRange AlignedByteRange;
         /*const*/ IBlockBufferPtr Buffer;
+        const bool DescribeOnly;
 
         ui64 CommitId = InvalidCommitId;
         ui64 NodeId = InvalidNodeId;
@@ -1133,18 +1134,21 @@ struct TTxIndexTablet
         // NOTE: should persist state across tx restarts
         TSet<ui32> MixedBlocksRanges;
 
+        template <typename TReadRequest>
         TReadData(
                 TRequestInfoPtr requestInfo,
-                const NProto::TReadDataRequest& request,
+                const TReadRequest& request,
                 TByteRange originByteRange,
                 TByteRange alignedByteRange,
-                IBlockBufferPtr buffer)
+                IBlockBufferPtr buffer,
+                bool describeOnly)
             : TSessionAware(request)
             , RequestInfo(std::move(requestInfo))
             , Handle(request.GetHandle())
             , OriginByteRange(originByteRange)
             , AlignedByteRange(alignedByteRange)
             , Buffer(std::move(buffer))
+            , DescribeOnly(describeOnly)
             , Blocks(AlignedByteRange.BlockCount())
             , Bytes(AlignedByteRange.BlockCount())
         {

cloud/filestore/private/api/protos/tablet.proto

@@ -6,6 +6,8 @@ import "cloud/filestore/public/api/protos/fs.proto";
 import "cloud/filestore/public/api/protos/headers.proto";
 import "cloud/filestore/config/storage.proto";
 
+import "contrib/ydb/core/protos/base.proto";
+
 package NCloud.NFileStore.NProtoPrivate;
 
 option go_package = "a.yandex-team.ru/cloud/filestore/private/api/protos";
@@ -209,7 +211,7 @@ message TGetFileSystemConfigResponse
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// GetStorageConfig fields request/response.
+// GetStorageConfigFields request/response.
 
 message TGetStorageConfigFieldsRequest
 {
@@ -233,7 +235,7 @@ message TGetStorageConfigFieldsResponse
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// Change StorageConfig request/response
+// ChangeStorageConfig request/response
 
 message TChangeStorageConfigRequest
 {
@@ -258,3 +260,72 @@ message TChangeStorageConfigResponse
     // Result Storage config.
     NProto.TStorageConfig StorageConfig = 2;
 }
+
+////////////////////////////////////////////////////////////////////////////////
+// DescribeData request/response.
+
+message TDescribeDataRequest
+{
+    // Optional request headers.
+    NProto.THeaders Headers = 1;
+
+    // FileSystem identifier.
+    string FileSystemId = 2;
+
+    // Node.
+    uint64 NodeId = 3;
+
+    // IO handle.
+    uint64 Handle = 4;
+
+    // Starting offset for read.
+    uint64 Offset = 5;
+
+    // Number of bytes to read.
+    uint64 Length = 6;
+}
+
+// Represents actual data - for the data that is not stored in data channels as
+// blobs yet.
+message TFreshDataRange
+{
+    // This offset is relative to the beginning of the inode.
+    uint64 Offset = 1;
+    // Data bytes.
+    bytes Content = 2;
+}
+
+// Represents a range of consecutive bytes inside some blob.
+message TRangeInBlob
+{
+    // This offset is relative to the beginning of the inode.
+    uint64 Offset = 1;
+    // This offset is relative to the beginning of the blob. Measured in bytes.
+    uint32 BlobOffset = 2;
+    uint32 Length = 3;
+}
+
+// Represents the ranges that need to be read from a single blob.
+message TBlobPiece
+{
+    // Blob id.
+    NKikimrProto.TLogoBlobID BlobId = 1;
+
+    // Group id.
+    uint32 BSGroupId = 2;
+
+    // Data ranges.
+    repeated TRangeInBlob Ranges = 3;
+}
+
+message TDescribeDataResponse
+{
+    // Optional error, set only if error happened.
+    NCloud.NProto.TError Error = 1;
+
+    repeated TFreshDataRange FreshDataRanges = 2;
+    repeated TBlobPiece BlobPieces = 3;
+
+    // Optional response headers.
+    NProto.TResponseHeaders Headers = 1000;
+}

cloud/filestore/private/api/protos/ya.make

@@ -1,12 +1,14 @@
 PROTO_LIBRARY(filestore-private-api-protos)
 
-INCLUDE_TAGS(GO_PROTO)
+EXCLUDE_TAGS(GO_PROTO)
 EXCLUDE_TAGS(JAVA_PROTO)
 
 PEERDIR(
     cloud/filestore/config
     cloud/filestore/public/api/protos
     cloud/storage/core/protos
+
+    contrib/ydb/core/protos
 )
 
 SRCS(