reduce blocking in scrub (#743)

* reduce held locks while performing scrub operation

1 files changed, 12 insertions, 11 deletions

diff --git a/src/zenstore/compactcas.cpp b/src/zenstore/compactcas.cpp
index 37a8c36b8..097102a1d 100644
--- a/src/zenstore/compactcas.cpp
+++ b/src/zenstore/compactcas.cpp
@@ -565,20 +565,21 @@ CasContainerStrategy::ScrubStorage(ScrubContext& Ctx)
 
 	try
 	{
-		RwLock::SharedLockScope _(m_LocationMapLock);
-
-		uint64_t TotalChunkCount = m_LocationMap.size();
-		ChunkLocations.reserve(TotalChunkCount);
-		ChunkIndexToChunkHash.reserve(TotalChunkCount);
 		{
-			for (const auto& Entry : m_LocationMap)
+			uint64_t TotalChunkCount = m_LocationMap.size();
+			ChunkLocations.reserve(TotalChunkCount);
+			ChunkIndexToChunkHash.reserve(TotalChunkCount);
+			RwLock::SharedLockScope _(m_LocationMapLock);
 			{
-				const IoHash&				  ChunkHash	   = Entry.first;
-				const BlockStoreDiskLocation& DiskLocation = m_Locations[Entry.second];
-				BlockStoreLocation			  Location	   = DiskLocation.Get(m_PayloadAlignment);
+				for (const auto& Entry : m_LocationMap)
+				{
+					const IoHash&				  ChunkHash	   = Entry.first;
+					const BlockStoreDiskLocation& DiskLocation = m_Locations[Entry.second];
+					BlockStoreLocation			  Location	   = DiskLocation.Get(m_PayloadAlignment);
 
-				ChunkLocations.push_back(Location);
-				ChunkIndexToChunkHash.push_back(ChunkHash);
+					ChunkLocations.push_back(Location);
+					ChunkIndexToChunkHash.push_back(ChunkHash);
+				}
 			}
 		}