issue-324: implemented LazyBlockBuffer and using it in TIndexTabletAc…

…tor::HandleDescribeData (#523)
ydb-platform · Feb 21, 2024 · 6f7d720 · 6f7d720
1 parent f9c1ed8
commit 6f7d720
Show file tree

Hide file tree

Showing 5 changed files with 69 additions and 5 deletions.
diff --git a/cloud/filestore/libs/storage/model/block_buffer.cpp b/cloud/filestore/libs/storage/model/block_buffer.cpp
@@ -61,6 +61,64 @@ class TBlockBuffer final
     }
 };
 
+////////////////////////////////////////////////////////////////////////////////
+
+class TLazyBlockBuffer final
+    : public IBlockBuffer
+{
+private:
+    const TByteRange ByteRange;
+    TString UnalignedHead;
+    TVector<TString> Blocks;
+    TString UnalignedTail;
+
+public:
+    explicit TLazyBlockBuffer(TByteRange byteRange)
+        : ByteRange(byteRange)
+        , Blocks(ByteRange.BlockCount())
+    {
+    }
+
+    TStringBuf GetUnalignedHead() override
+    {
+        if (!UnalignedHead) {
+            UnalignedHead.ReserveAndResize(ByteRange.UnalignedHeadLength());
+        }
+
+        return UnalignedHead;
+    }
+
+    TStringBuf GetUnalignedTail() override
+    {
+        if (!UnalignedTail) {
+            UnalignedTail.ReserveAndResize(ByteRange.UnalignedTailLength());
+        }
+
+        return UnalignedTail;
+    }
+
+    TStringBuf GetBlock(size_t index) override
+    {
+        auto& block = Blocks[index];
+        if (!block) {
+            block.ReserveAndResize(ByteRange.BlockSize);
+        }
+
+        return block;
+    }
+
+    void SetBlock(size_t index, TStringBuf block) override
+    {
+        Y_ABORT_UNLESS(block.size() == ByteRange.BlockSize);
+        Blocks[index] = block;
+    }
+
+    void ClearBlock(size_t index) override
+    {
+        Blocks[index].clear();
+    }
+};
+
 }   // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -78,6 +136,11 @@ IBlockBufferPtr CreateBlockBuffer(TByteRange byteRange, TString buffer)
     return std::make_shared<TBlockBuffer>(byteRange, std::move(buffer));
 }
 
+IBlockBufferPtr CreateLazyBlockBuffer(TByteRange byteRange)
+{
+    return std::make_shared<TLazyBlockBuffer>(byteRange);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void CopyFileData(

diff --git a/cloud/filestore/libs/storage/model/block_buffer.h b/cloud/filestore/libs/storage/model/block_buffer.h
@@ -26,6 +26,7 @@ struct IBlockBuffer
 
 IBlockBufferPtr CreateBlockBuffer(TByteRange byteRange);
 IBlockBufferPtr CreateBlockBuffer(TByteRange byteRange, TString buffer);
+IBlockBufferPtr CreateLazyBlockBuffer(TByteRange byteRange);
 
 ////////////////////////////////////////////////////////////////////////////////
 

diff --git a/cloud/filestore/libs/storage/service/service_actor_readdata.cpp b/cloud/filestore/libs/storage/service/service_actor_readdata.cpp
@@ -207,6 +207,7 @@ void ApplyFreshDataRange(
         targetBuffer);
 
     // NB: we assume that underlying target data is a continuous buffer
+    // TODO: don't make such an assumption - use GetBlock(i) API
     memcpy(
         targetData,
         sourceFreshData.GetContent().data() +

diff --git a/cloud/filestore/libs/storage/service/service_ut.cpp b/cloud/filestore/libs/storage/service/service_ut.cpp
@@ -1546,8 +1546,9 @@ Y_UNIT_TEST_SUITE(TStorageServiceTest)
             service.ReadData(headers, fs, nodeId, handle, 0, data.Size());
         UNIT_ASSERT_VALUES_EQUAL(readDataResult->Record.GetBuffer(), data);
 
-        // fresh blocks
-        data = TString(4_KB, 'a');
+        // fresh blocks - adding multiple adjacent blocks is important here to
+        // catch some subtle bugs
+        data = TString(8_KB, 'a');
         service.WriteData(headers, fs, nodeId, handle, 0, data);
         readDataResult =
             service.ReadData(headers, fs, nodeId, handle, 0, data.Size());

diff --git a/cloud/filestore/libs/storage/tablet/tablet_actor_readdata.cpp b/cloud/filestore/libs/storage/tablet/tablet_actor_readdata.cpp
@@ -602,9 +602,7 @@ void TIndexTabletActor::HandleDescribeData(
     requestInfo->StartedTs = ctx.Now();
 
     TByteRange alignedByteRange = byteRange.AlignedSuperRange();
-    // TODO: implement a block buffer with lazy block allocation and use it
-    // here
-    auto blockBuffer = CreateBlockBuffer(alignedByteRange);
+    auto blockBuffer = CreateLazyBlockBuffer(alignedByteRange);
 
     ExecuteTx<TReadData>(
         ctx,