fix missing locks/sync of log position when writing index snapshots (#572)

* fix missing locks/sync of log position when writing index snapshots
* changelog

3 files changed, 10 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d819bf28c..7bb2f34ea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Feature: Added `zen gc-stop` command to cancel a running garbage collect operation
 - Bugfix: Fix sentry host name where last character of name was being truncated
 - Bugfix: GCv2 - make sure to discover all projects and oplogs before checking for expired data
+- Bugfix: Fix sync of log position and state log when writing cas index snapshot
 - Improvement: The frontend html content is no longer appended at the end of the executable which prevented signing, instead it is compiled in from the `/src/zenserver/frontend/html.zip` archive
 - Improvement: MacOS now does ad-hoc code signing by default when issuing `xmake bundle`, signing with proper cert is done on CI builds
 - Improvement: Updated branding to be consistent with current working name ("Unreal Zen Storage Server" etc)
diff --git a/src/zenstore/compactcas.cpp b/src/zenstore/compactcas.cpp
index 95198fd59..c4f9ff2c6 100644
--- a/src/zenstore/compactcas.cpp
+++ b/src/zenstore/compactcas.cpp
@@ -884,9 +884,11 @@ CasContainerStrategy::MakeIndexSnapshot()
 
 		// Write the current state of the location map to a new index state
 		std::vector<CasDiskIndexEntry> Entries;
+		uint64_t					   IndexLogPosition = 0;
 
 		{
 			RwLock::SharedLockScope ___(m_LocationMapLock);
+			IndexLogPosition = m_CasLog.GetLogCount();
 			Entries.resize(m_LocationMap.size());
 
 			uint64_t EntryIndex = 0;
@@ -901,7 +903,7 @@ CasContainerStrategy::MakeIndexSnapshot()
 		BasicFile ObjectIndexFile;
 		ObjectIndexFile.Open(IndexPath, BasicFile::Mode::kTruncate);
 		CasDiskIndexHeader Header = {.EntryCount	   = Entries.size(),
-									 .LogPosition	   = LogCount,
+									 .LogPosition	   = IndexLogPosition,
 									 .PayloadAlignment = gsl::narrow<uint32_t>(m_PayloadAlignment)};
 
 		Header.Checksum = CasDiskIndexHeader::ComputeChecksum(Header);
@@ -911,7 +913,7 @@ CasContainerStrategy::MakeIndexSnapshot()
 		ObjectIndexFile.Flush();
 		ObjectIndexFile.Close();
 		EntryCount		   = Entries.size();
-		m_LogFlushPosition = LogCount;
+		m_LogFlushPosition = IndexLogPosition;
 	}
 	catch (std::exception& Err)
 	{
diff --git a/src/zenstore/filecas.cpp b/src/zenstore/filecas.cpp
index 6ba282163..bf12a0c1a 100644
--- a/src/zenstore/filecas.cpp
+++ b/src/zenstore/filecas.cpp
@@ -1097,8 +1097,11 @@ FileCasStrategy::MakeIndexSnapshot()
 
 		// Write the current state of the location map to a new index state
 		std::vector<FileCasIndexEntry> Entries;
+		uint64_t					   IndexLogPosition = 0;
 
 		{
+			RwLock::SharedLockScope __(m_Lock);
+			IndexLogPosition = m_CasLog.GetLogCount();
 			Entries.resize(m_Index.size());
 
 			uint64_t EntryIndex = 0;
@@ -1112,7 +1115,7 @@ FileCasStrategy::MakeIndexSnapshot()
 
 		BasicFile ObjectIndexFile;
 		ObjectIndexFile.Open(IndexPath, BasicFile::Mode::kTruncate);
-		filecas::impl::FileCasIndexHeader Header = {.EntryCount = Entries.size(), .LogPosition = LogCount};
+		filecas::impl::FileCasIndexHeader Header = {.EntryCount = Entries.size(), .LogPosition = IndexLogPosition};
 
 		Header.Checksum = filecas::impl::FileCasIndexHeader::ComputeChecksum(Header);
 
@@ -1121,7 +1124,7 @@ FileCasStrategy::MakeIndexSnapshot()
 		ObjectIndexFile.Flush();
 		ObjectIndexFile.Close();
 		EntryCount		   = Entries.size();
-		m_LogFlushPosition = LogCount;
+		m_LogFlushPosition = IndexLogPosition;
 	}
 	catch (std::exception& Err)
 	{