meta info store (#75)

- Feature: Added option `--gc-cache-attachment-store` which caches referenced attachments in cache records on disk for faster GC - default is `false`
- Feature: Added option `--gc-projectstore-attachment-store` which caches referenced attachments in project store oplogs on disk for faster GC - default is `false`

1 files changed, 147 insertions, 7 deletions

diff --git a/src/zenstore/blockstore.cpp b/src/zenstore/blockstore.cpp
index 70ddcedaf..287a3f7fa 100644
--- a/src/zenstore/blockstore.cpp
+++ b/src/zenstore/blockstore.cpp
@@ -90,6 +90,7 @@ BlockStoreFile::Create(uint64_t InitialSize)
 		RetriesLeft--;
 		return true;
 	});
+	RemoveMeta();
 
 	void* FileHandle = m_File.Handle();
 
@@ -99,15 +100,26 @@ BlockStoreFile::Create(uint64_t InitialSize)
 }
 
 uint64_t
-BlockStoreFile::FileSize()
+BlockStoreFile::FileSize() const
 {
-	return m_CachedFileSize == 0 ? m_File.FileSize() : m_CachedFileSize;
+	if (m_CachedFileSize == 0)
+	{
+		std::error_code Ec;
+		uint64_t		Size = m_File.FileSize(Ec);
+		if (Ec)
+		{
+			return 0;
+		}
+		return Size;
+	}
+	return m_CachedFileSize;
 }
 
 void
 BlockStoreFile::MarkAsDeleteOnClose()
 {
 	m_IoBuffer.SetDeleteOnClose(true);
+	RemoveMeta();
 }
 
 IoBuffer
@@ -157,6 +169,90 @@ BlockStoreFile::IsOpen() const
 	return !!m_IoBuffer;
 }
 
+bool
+BlockStoreFile::SetMetaData(const IoBuffer& Payload)
+{
+	if (!Payload)
+	{
+		RemoveMeta();
+		return true;
+	}
+	const std::filesystem::path MetaPath = GetMetaPath();
+	std::error_code				Ec;
+	TemporaryFile::SafeWriteFile(MetaPath, Payload.GetView(), Ec);
+	if (Ec)
+	{
+		ZEN_WARN("Unable to set meta data for block '{}' at meta path: '{}'. Reason: '{}'", m_Path, MetaPath, Ec.message());
+		return false;
+	}
+	return true;
+}
+
+static bool
+IsMetaDataValid(const std::filesystem::path& BlockPath, const std::filesystem::path& MetaPath)
+{
+	std::error_code					Ec;
+	std::filesystem::file_time_type MetaWriteTime = std::filesystem::last_write_time(MetaPath, Ec);
+	if (Ec)
+	{
+		return false;
+	}
+	std::filesystem::file_time_type BlockWriteTime = std::filesystem::last_write_time(BlockPath, Ec);
+	if (Ec)
+	{
+		return false;
+	}
+	if (MetaWriteTime < BlockWriteTime)
+	{
+		std::filesystem::remove(MetaPath, Ec);
+		return false;
+	}
+	return true;
+}
+
+IoBuffer
+BlockStoreFile::GetMetaData() const
+{
+	const std::filesystem::path MetaPath = GetMetaPath();
+	if (IsMetaDataValid(m_Path, MetaPath))
+	{
+		return IoBufferBuilder::MakeFromFile(MetaPath);
+	}
+	return {};
+}
+
+uint64_t
+BlockStoreFile::MetaSize() const
+{
+	const std::filesystem::path MetaPath = GetMetaPath();
+	if (IsMetaDataValid(m_Path, MetaPath))
+	{
+		std::error_code DummyEc;
+		if (uint64_t Size = std::filesystem::file_size(MetaPath, DummyEc); !DummyEc)
+		{
+			return Size;
+		}
+	}
+	return 0;
+}
+
+void
+BlockStoreFile::RemoveMeta()
+{
+	std::filesystem::path MetaPath = GetMetaPath();
+	std::error_code		  DummyEc;
+	std::filesystem::remove(MetaPath, DummyEc);
+}
+
+std::filesystem::path
+BlockStoreFile::GetMetaPath() const
+{
+	std::filesystem::path MetaPath(m_Path);
+	return MetaPath.replace_extension(".meta");
+}
+
+////////////////////////////////////////////////////////
+
 constexpr uint64_t DefaultIterateSmallChunkWindowSize = 2 * 1024 * 1024;
 constexpr uint64_t IterateSmallChunkMaxGapSize		  = 4 * 1024;
 
@@ -215,7 +311,7 @@ BlockStore::Initialize(const std::filesystem::path& BlocksBasePath, uint64_t Max
 					}
 					Ref<BlockStoreFile> BlockFile{new BlockStoreFile(Path)};
 					BlockFile->Open();
-					m_TotalSize.fetch_add(BlockFile->FileSize(), std::memory_order::relaxed);
+					m_TotalSize.fetch_add(BlockFile->TotalSize(), std::memory_order::relaxed);
 					m_ChunkBlocks[BlockIndex] = BlockFile;
 					FoundBlocks[BlockIndex]	  = BlockFile->FileSize();
 					if (BlockIndex >= NextBlockIndex)
@@ -283,7 +379,7 @@ BlockStore::SyncExistingBlocksOnDisk(const BlockIndexSet& KnownLocations)
 		std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, BlockIndex);
 		if (m_ChunkBlocks[BlockIndex])
 		{
-			m_TotalSize.fetch_sub(m_ChunkBlocks[BlockIndex]->FileSize(), std::memory_order::relaxed);
+			m_TotalSize.fetch_sub(m_ChunkBlocks[BlockIndex]->TotalSize(), std::memory_order::relaxed);
 			m_ChunkBlocks[BlockIndex]->MarkAsDeleteOnClose();
 		}
 		m_ChunkBlocks.erase(BlockIndex);
@@ -781,6 +877,7 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 			   {
 				   ZEN_DEBUG("dropping incomplete cas block store file '{}'", NewBlockFile->GetPath());
 				   m_TotalSize.fetch_sub(NewBlockFile->FileSize(), std::memory_order::relaxed);
+				   ZEN_ASSERT_SLOW(NewBlockFile->MetaSize() == 0);
 				   NewBlockFile->MarkAsDeleteOnClose();
 			   }
 		   });
@@ -833,7 +930,7 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 					ZEN_DEBUG("marking cas block store file '{}' for delete, block #{}", OldBlockFile->GetPath(), BlockIndex);
 					ZEN_ASSERT(m_ChunkBlocks[BlockIndex] == OldBlockFile);
 					m_ChunkBlocks.erase(BlockIndex);
-					m_TotalSize.fetch_sub(OldBlockFile->FileSize(), std::memory_order::relaxed);
+					m_TotalSize.fetch_sub(OldBlockFile->TotalSize(), std::memory_order::relaxed);
 					OldBlockFile->MarkAsDeleteOnClose();
 				}
 				continue;
@@ -1003,7 +1100,7 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 				ZEN_DEBUG("marking cas block store file '{}' for delete, block #{}", OldBlockFile->GetPath(), BlockIndex);
 				ZEN_ASSERT(m_ChunkBlocks[BlockIndex] == OldBlockFile);
 				m_ChunkBlocks.erase(BlockIndex);
-				m_TotalSize.fetch_sub(OldBlockFile->FileSize(), std::memory_order::relaxed);
+				m_TotalSize.fetch_sub(OldBlockFile->TotalSize(), std::memory_order::relaxed);
 				OldBlockFile->MarkAsDeleteOnClose();
 			}
 		}
@@ -1500,9 +1597,10 @@ BlockStore::CompactBlocks(const BlockStoreCompactState&	  CompactState,
 					  LogPrefix,
 					  OldBlockFile->GetPath().filename(),
 					  NiceBytes(OldBlockSize));
+			m_TotalSize.fetch_sub(OldBlockSize);
+			m_TotalSize.fetch_sub(OldBlockFile->MetaSize());
 			OldBlockFile->MarkAsDeleteOnClose();
 			m_ChunkBlocks.erase(BlockIndex);
-			m_TotalSize.fetch_sub(OldBlockSize);
 			RemovedSize += OldBlockSize;
 		}
 		return true;
@@ -1544,6 +1642,48 @@ BlockStore::GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint
 	return Path.ToPath();
 }
 
+bool
+BlockStore::IsWriting(uint32_t BlockIndex) const
+{
+	RwLock::SharedLockScope _(m_InsertLock);
+	if (std::find(m_ActiveWriteBlocks.begin(), m_ActiveWriteBlocks.end(), BlockIndex) != m_ActiveWriteBlocks.end())
+	{
+		return true;
+	}
+	if (BlockIndex == m_WriteBlockIndex.load() && m_WriteBlock)
+	{
+		return true;
+	}
+	return false;
+}
+
+void
+BlockStore::SetMetaData(uint32_t BlockIndex, const IoBuffer& Payload)
+{
+	RwLock::ExclusiveLockScope _(m_InsertLock);
+	if (auto It = m_ChunkBlocks.find(BlockIndex); It != m_ChunkBlocks.end() && It->second)
+	{
+		uint64_t OldMetaSize = It->second->MetaSize();
+		if (It->second->SetMetaData(Payload))
+		{
+			uint64_t NewMetaSize = It->second->MetaSize();
+			m_TotalSize += NewMetaSize;
+			m_TotalSize -= OldMetaSize;
+		}
+	}
+}
+
+IoBuffer
+BlockStore::GetMetaData(uint32_t BlockIndex) const
+{
+	RwLock::SharedLockScope _(m_InsertLock);
+	if (auto It = m_ChunkBlocks.find(BlockIndex); It != m_ChunkBlocks.end() && It->second)
+	{
+		return It->second->GetMetaData();
+	}
+	return {};
+}
+
 #if ZEN_WITH_TESTS
 
 TEST_CASE("blockstore.blockstoredisklocation")