flush cas log file (#387)

* make sure we remove the cas log file when writing full index at startup

1 files changed, 30 insertions, 45 deletions

diff --git a/src/zenstore/compactcas.cpp b/src/zenstore/compactcas.cpp
index 90e77e48a..a8914ed20 100644
--- a/src/zenstore/compactcas.cpp
+++ b/src/zenstore/compactcas.cpp
@@ -461,7 +461,7 @@ CasContainerStrategy::Flush()
 	ZEN_TRACE_CPU("CasContainer::Flush");
 	m_BlockStore.Flush(/*ForceNewBlock*/ false);
 	m_CasLog.Flush();
-	MakeIndexSnapshot();
+	MakeIndexSnapshot(/*FlushLockPosition*/ false);
 }
 
 void
@@ -924,12 +924,12 @@ CasContainerStrategy::StorageSize() const
 }
 
 void
-CasContainerStrategy::MakeIndexSnapshot()
+CasContainerStrategy::MakeIndexSnapshot(bool FlushLockPosition)
 {
 	ZEN_MEMSCOPE(GetCasContainerTag());
 	ZEN_TRACE_CPU("CasContainer::MakeIndexSnapshot");
 
-	uint64_t LogCount = m_CasLog.GetLogCount();
+	const uint64_t LogCount = FlushLockPosition ? 0 : m_CasLog.GetLogCount();
 	if (m_LogFlushPosition == LogCount)
 	{
 		return;
@@ -947,27 +947,10 @@ CasContainerStrategy::MakeIndexSnapshot()
 
 	namespace fs = std::filesystem;
 
-	fs::path IndexPath	   = cas::impl::GetIndexPath(m_RootDirectory, m_ContainerBaseName);
-	fs::path TempIndexPath = cas::impl::GetTempIndexPath(m_RootDirectory, m_ContainerBaseName);
-
-	// Move index away, we keep it if something goes wrong
-	if (IsFile(TempIndexPath))
-	{
-		std::error_code Ec;
-		if (!RemoveFile(TempIndexPath, Ec) || Ec)
-		{
-			ZEN_WARN("snapshot failed to clean up temp snapshot at {}, reason: '{}'", TempIndexPath, Ec.message());
-			return;
-		}
-	}
+	fs::path IndexPath = cas::impl::GetIndexPath(m_RootDirectory, m_ContainerBaseName);
 
 	try
 	{
-		if (IsFile(IndexPath))
-		{
-			RenameFile(IndexPath, TempIndexPath);
-		}
-
 		// Write the current state of the location map to a new index state
 		std::vector<CasDiskIndexEntry> Entries;
 		uint64_t					   IndexLogPosition = 0;
@@ -993,7 +976,8 @@ CasContainerStrategy::MakeIndexSnapshot()
 		{
 			throw std::system_error(Ec, fmt::format("Failed to create temp file for index snapshot at '{}'", IndexPath));
 		}
-		CasDiskIndexHeader Header = {.EntryCount	   = Entries.size(),
+		EntryCount				  = Entries.size();
+		CasDiskIndexHeader Header = {.EntryCount	   = EntryCount,
 									 .LogPosition	   = IndexLogPosition,
 									 .PayloadAlignment = gsl::narrow<uint32_t>(m_PayloadAlignment)};
 
@@ -1005,36 +989,37 @@ CasContainerStrategy::MakeIndexSnapshot()
 		ObjectIndexFile.MoveTemporaryIntoPlace(IndexPath, Ec);
 		if (Ec)
 		{
-			throw std::system_error(Ec, fmt::format("Failed to move temp file '{}' to '{}'", ObjectIndexFile.GetPath(), IndexPath));
+			ZEN_WARN("snapshot failed to rename new snapshot '{}' to '{}', reason: '{}'",
+					 ObjectIndexFile.GetPath(),
+					 IndexPath,
+					 Ec.message());
 		}
-		EntryCount		   = Entries.size();
-		m_LogFlushPosition = IndexLogPosition;
-	}
-	catch (const std::exception& Err)
-	{
-		ZEN_WARN("snapshot FAILED, reason: '{}'", Err.what());
-
-		// Restore any previous snapshot
-
-		if (IsFile(TempIndexPath))
+		if (FlushLockPosition)
 		{
-			std::error_code Ec;
-			RemoveFile(IndexPath, Ec);	// We don't care if this fails, we try to move the old temp file regardless
-			RenameFile(TempIndexPath, IndexPath, Ec);
-			if (Ec)
+			std::filesystem::path LogPath = cas::impl::GetLogPath(m_RootDirectory, m_ContainerBaseName);
+
+			if (IsFile(LogPath))
 			{
-				ZEN_WARN("snapshot failed to restore old snapshot from {}, reason: '{}'", TempIndexPath, Ec.message());
+				if (!RemoveFile(LogPath, Ec) || Ec)
+				{
+					ZEN_WARN("snapshot failed to clean log file '{}', removing index at '{}', reason: '{}'",
+							 LogPath,
+							 IndexPath,
+							 Ec.message());
+					std::error_code RemoveIndexEc;
+					RemoveFile(IndexPath, RemoveIndexEc);
+				}
 			}
 		}
-	}
-	if (IsFile(TempIndexPath))
-	{
-		std::error_code Ec;
-		if (!RemoveFile(TempIndexPath, Ec) || Ec)
+		if (!Ec)
 		{
-			ZEN_WARN("snapshot failed to remove temporary file {}, reason: '{}'", TempIndexPath, Ec.message());
+			m_LogFlushPosition = LogCount;
 		}
 	}
+	catch (const std::exception& Err)
+	{
+		ZEN_WARN("snapshot FAILED, reason: '{}'", Err.what());
+	}
 }
 
 uint64_t
@@ -1229,7 +1214,7 @@ CasContainerStrategy::OpenContainer(bool IsNewStore)
 
 	if (IsNewStore || (LogEntryCount > 0))
 	{
-		MakeIndexSnapshot();
+		MakeIndexSnapshot(/*FlushLockPosition*/ true);
 	}
 
 	// TODO: should validate integrity of container files here