gc v2 disk freed space fix and oplog stats report improvement (#45)

- Bugfix: Correctly calculate size freed/data moved from blocks in GCv2
- Improvement: Reduced details in remote store stats for oplog export/import to user
- Improvement: Transfer speed for oplog export/import is now an overall number rather than average of speed per single request

1 files changed, 15 insertions, 10 deletions

diff --git a/src/zenstore/blockstore.cpp b/src/zenstore/blockstore.cpp
index a576ff022..644ddf7b4 100644
--- a/src/zenstore/blockstore.cpp
+++ b/src/zenstore/blockstore.cpp
@@ -1093,7 +1093,6 @@ BlockStore::CompactBlocks(const BlockStoreCompactState&	  CompactState,
 				  NiceBytes(MovedSize));
 	});
 
-	uint64_t		 WriteOffset   = m_MaxBlockSize + 1u;  // Force detect a new block
 	uint32_t		 NewBlockIndex = 0;
 	MovedChunksArray MovedChunks;
 
@@ -1188,8 +1187,11 @@ BlockStore::CompactBlocks(const BlockStoreCompactState&	  CompactState,
 			std::sort(SortedChunkIndexes.begin(), SortedChunkIndexes.end(), [&ChunkLocations](size_t Lhs, size_t Rhs) {
 				return ChunkLocations[Lhs].Offset < ChunkLocations[Rhs].Offset;
 			});
-			BasicFileBuffer		 SourceFileBuffer(OldBlockFile->GetBasicFile(), Min(65536u, OldBlockSize));
-			uint64_t			 MovedFromBlock = 0;
+			BasicFileBuffer SourceFileBuffer(OldBlockFile->GetBasicFile(), Min(65536u, OldBlockSize));
+
+			uint64_t			 WriteOffset		 = m_MaxBlockSize + 1u;	 // Force detect a new block
+			uint64_t			 WrittenBytesToBlock = 0;
+			uint64_t			 MovedFromBlock		 = 0;
 			std::vector<uint8_t> Chunk;
 			for (const size_t& ChunkIndex : SortedChunkIndexes)
 			{
@@ -1295,19 +1297,22 @@ BlockStore::CompactBlocks(const BlockStoreCompactState&	  CompactState,
 								 NiceBytes(Space.Free + ReclaimedSpace));
 					}
 					NewBlockFile->Create(m_MaxBlockSize);
-					NewBlockIndex	 = NextBlockIndex;
-					WriteOffset		 = 0;
-					TargetFileBuffer = std::make_unique<BasicFileWriter>(NewBlockFile->GetBasicFile(), Min(65536u, m_MaxBlockSize));
+					NewBlockIndex = NextBlockIndex;
+					WriteOffset	  = 0;
+					AddedSize += WrittenBytesToBlock;
+					WrittenBytesToBlock = 0;
+					TargetFileBuffer	= std::make_unique<BasicFileWriter>(NewBlockFile->GetBasicFile(), Min(65536u, m_MaxBlockSize));
 				}
 
 				TargetFileBuffer->Write(Chunk.data(), ChunkLocation.Size, WriteOffset);
 				MovedChunks.push_back(
 					{ChunkIndex, {.BlockIndex = NewBlockIndex, .Offset = gsl::narrow<uint32_t>(WriteOffset), .Size = ChunkLocation.Size}});
-				uint64_t WriteEndOffset = WriteOffset + ChunkLocation.Size;
-				MovedFromBlock += (WriteEndOffset - WriteOffset);
-				WriteOffset = RoundUp(WriteEndOffset, PayloadAlignment);
-				AddedSize += Chunk.size();
+				WrittenBytesToBlock = WriteOffset + ChunkLocation.Size;
+
+				MovedFromBlock += RoundUp(ChunkLocation.Offset + ChunkLocation.Size, PayloadAlignment) - ChunkLocation.Offset;
+				WriteOffset = RoundUp(WriteOffset + ChunkLocation.Size, PayloadAlignment);
 			}
+			AddedSize += WrittenBytesToBlock;
 			ZEN_INFO("{}moved {} chunks ({}) from '{}' to new block, freeing {}",
 					 LogPrefix,
 					 KeepChunkIndexes.size(),