Make sure we monitor for new project, oplogs, namespaces and buckets during GCv2 (#93)

- Bugfix: Make sure we monitor and include new project/oplogs created during GCv2
- Bugfix: Make sure we monitor and include new namespaces/cache buckets created during GCv2

1 files changed, 370 insertions, 99 deletions

diff --git a/src/zenserver/projectstore/projectstore.cpp b/src/zenserver/projectstore/projectstore.cpp
index 4c434c39b..beac1ab97 100644
--- a/src/zenserver/projectstore/projectstore.cpp
+++ b/src/zenserver/projectstore/projectstore.cpp
@@ -1094,6 +1094,12 @@ void
 ProjectStore::Oplog::IterateOplog(std::function<void(CbObjectView)>&& Handler)
 {
 	RwLock::SharedLockScope _(m_OplogLock);
+	IterateOplogLocked(std::move(Handler));
+}
+
+void
+ProjectStore::Oplog::IterateOplogLocked(std::function<void(CbObjectView)>&& Handler)
+{
 	if (!m_Storage)
 	{
 		return;
@@ -1264,22 +1270,25 @@ ProjectStore::Oplog::AddChunkMappings(const std::unordered_map<Oid, IoHash, Oid:
 }
 
 void
-ProjectStore::Oplog::CaptureUpdatedLSN(RwLock::ExclusiveLockScope&, uint32_t LSN)
+ProjectStore::Oplog::CaptureUpdatedLSNs(std::span<const uint32_t> LSNs)
 {
-	if (m_UpdatedLSNs)
-	{
-		m_UpdatedLSNs->push_back(LSN);
-	}
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		if (m_CapturedLSNs)
+		{
+			m_CapturedLSNs->reserve(m_CapturedLSNs->size() + LSNs.size());
+			m_CapturedLSNs->insert(m_CapturedLSNs->end(), LSNs.begin(), LSNs.end());
+		}
+	});
 }
 
 void
 ProjectStore::Oplog::CaptureAddedAttachments(std::span<const IoHash> AttachmentHashes)
 {
-	m_OplogLock.WithExclusiveLock([this, AttachmentHashes]() {
-		if (m_NonGCAttachments)
+	m_UpdateCaptureLock.WithExclusiveLock([this, AttachmentHashes]() {
+		if (m_CapturedAttachments)
 		{
-			m_NonGCAttachments->reserve(m_NonGCAttachments->size() + AttachmentHashes.size());
-			m_NonGCAttachments->insert(m_NonGCAttachments->end(), AttachmentHashes.begin(), AttachmentHashes.end());
+			m_CapturedAttachments->reserve(m_CapturedAttachments->size() + AttachmentHashes.size());
+			m_CapturedAttachments->insert(m_CapturedAttachments->end(), AttachmentHashes.begin(), AttachmentHashes.end());
 		}
 	});
 }
@@ -1287,18 +1296,18 @@ ProjectStore::Oplog::CaptureAddedAttachments(std::span<const IoHash> AttachmentH
 void
 ProjectStore::Oplog::EnableUpdateCapture()
 {
-	m_OplogLock.WithExclusiveLock([&]() {
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
 		if (m_UpdateCaptureRefCounter == 0)
 		{
-			ZEN_ASSERT(!m_UpdatedLSNs);
-			ZEN_ASSERT(!m_NonGCAttachments);
-			m_UpdatedLSNs	   = std::make_unique<std::vector<int>>();
-			m_NonGCAttachments = std::make_unique<std::vector<IoHash>>();
+			ZEN_ASSERT(!m_CapturedLSNs);
+			ZEN_ASSERT(!m_CapturedAttachments);
+			m_CapturedLSNs		  = std::make_unique<std::vector<uint32_t>>();
+			m_CapturedAttachments = std::make_unique<std::vector<IoHash>>();
 		}
 		else
 		{
-			ZEN_ASSERT(m_UpdatedLSNs);
-			ZEN_ASSERT(m_NonGCAttachments);
+			ZEN_ASSERT(m_CapturedLSNs);
+			ZEN_ASSERT(m_CapturedAttachments);
 		}
 		m_UpdateCaptureRefCounter++;
 	});
@@ -1307,51 +1316,49 @@ ProjectStore::Oplog::EnableUpdateCapture()
 void
 ProjectStore::Oplog::DisableUpdateCapture()
 {
-	m_OplogLock.WithExclusiveLock([&]() {
-		ZEN_ASSERT(m_UpdatedLSNs);
-		ZEN_ASSERT(m_NonGCAttachments);
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		ZEN_ASSERT(m_CapturedLSNs);
+		ZEN_ASSERT(m_CapturedAttachments);
 		ZEN_ASSERT(m_UpdateCaptureRefCounter > 0);
 		m_UpdateCaptureRefCounter--;
 		if (m_UpdateCaptureRefCounter == 0)
 		{
-			m_UpdatedLSNs.reset();
-			m_NonGCAttachments.reset();
+			m_CapturedLSNs.reset();
+			m_CapturedAttachments.reset();
 		}
 	});
 }
 
 void
-ProjectStore::Oplog::IterateUpdatedLSNs(RwLock::SharedLockScope&, std::function<bool(const CbObjectView& UpdateOp)>&& Callback)
+ProjectStore::Oplog::IterateCapturedLSNs(std::function<bool(const CbObjectView& UpdateOp)>&& Callback)
 {
-	if (m_UpdatedLSNs)
-	{
-		if (!m_Storage)
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		if (m_CapturedLSNs)
 		{
-			return;
-		}
-		for (int UpdatedLSN : *m_UpdatedLSNs)
-		{
-			if (const auto AddressEntryIt = m_OpAddressMap.find(UpdatedLSN); AddressEntryIt != m_OpAddressMap.end())
+			if (!m_Storage)
 			{
-				Callback(m_Storage->GetOp(AddressEntryIt->second));
+				return;
+			}
+			for (int UpdatedLSN : *m_CapturedLSNs)
+			{
+				if (const auto AddressEntryIt = m_OpAddressMap.find(UpdatedLSN); AddressEntryIt != m_OpAddressMap.end())
+				{
+					Callback(m_Storage->GetOp(AddressEntryIt->second));
+				}
 			}
 		}
-	}
+	});
 }
 
-void
-ProjectStore::Oplog::IterateAddedAttachments(RwLock::SharedLockScope&, std::function<bool(const IoHash& RawHash)>&& Callback)
+std::vector<IoHash>
+ProjectStore::Oplog::GetCapturedAttachments()
 {
-	if (m_NonGCAttachments)
+	RwLock::SharedLockScope _(m_UpdateCaptureLock);
+	if (m_CapturedAttachments)
 	{
-		for (const IoHash& ReferenceHash : *m_NonGCAttachments)
-		{
-			if (!Callback(ReferenceHash))
-			{
-				break;
-			}
-		}
+		return *m_CapturedAttachments;
 	}
+	return {};
 }
 
 void
@@ -1511,9 +1518,6 @@ ProjectStore::Oplog::RegisterOplogEntry(RwLock::ExclusiveLockScope& OplogLock,
 
 	m_OpAddressMap.emplace(OpEntry.OpLsn, OplogEntryAddress{.Offset = OpEntry.OpCoreOffset, .Size = OpEntry.OpCoreSize});
 	m_LatestOpMap[OpEntry.OpKeyHash] = OpEntry.OpLsn;
-
-	CaptureUpdatedLSN(OplogLock, OpEntry.OpLsn);
-
 	return OpEntry.OpLsn;
 }
 
@@ -1605,6 +1609,7 @@ ProjectStore::Oplog::AppendNewOplogEntry(CbObjectView Core)
 
 	RwLock::ExclusiveLockScope OplogLock(m_OplogLock);
 	const uint32_t			   EntryId = RegisterOplogEntry(OplogLock, Mapping, OpEntry);
+	CaptureUpdatedLSNs(std::array<uint32_t, 1u>({EntryId}));
 
 	return EntryId;
 }
@@ -1645,6 +1650,7 @@ ProjectStore::Oplog::AppendNewOplogEntries(std::span<CbObjectView> Cores)
 		{
 			EntryIds[OpIndex] = RegisterOplogEntry(OplogLock, Mappings[OpIndex], OpEntries[OpIndex]);
 		}
+		CaptureUpdatedLSNs(EntryIds);
 	}
 	return EntryIds;
 }
@@ -1868,6 +1874,14 @@ ProjectStore::Project::NewOplog(std::string_view OplogId, const std::filesystem:
 						 .first->second.get();
 
 		Log->Write();
+
+		m_UpdateCaptureLock.WithExclusiveLock([&]() {
+			if (m_CapturedOplogs)
+			{
+				m_CapturedOplogs->push_back(std::string(OplogId));
+			}
+		});
+
 		return Log;
 	}
 	catch (const std::exception&)
@@ -2125,6 +2139,61 @@ ProjectStore::Project::PrepareForDelete(std::filesystem::path& OutDeletePath)
 	return true;
 }
 
+void
+ProjectStore::Project::EnableUpdateCapture()
+{
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		if (m_UpdateCaptureRefCounter == 0)
+		{
+			ZEN_ASSERT(!m_CapturedOplogs);
+			m_CapturedOplogs = std::make_unique<std::vector<std::string>>();
+		}
+		else
+		{
+			ZEN_ASSERT(m_CapturedOplogs);
+		}
+		m_UpdateCaptureRefCounter++;
+	});
+}
+
+void
+ProjectStore::Project::DisableUpdateCapture()
+{
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		ZEN_ASSERT(m_CapturedOplogs);
+		ZEN_ASSERT(m_UpdateCaptureRefCounter > 0);
+		m_UpdateCaptureRefCounter--;
+		if (m_UpdateCaptureRefCounter == 0)
+		{
+			m_CapturedOplogs.reset();
+		}
+	});
+}
+
+std::vector<std::string>
+ProjectStore::Project::GetCapturedOplogs()
+{
+	RwLock::SharedLockScope _(m_UpdateCaptureLock);
+	if (m_CapturedOplogs)
+	{
+		return *m_CapturedOplogs;
+	}
+	return {};
+}
+
+std::vector<RwLock::SharedLockScope>
+ProjectStore::Project::GetGcReferencerLocks()
+{
+	std::vector<RwLock::SharedLockScope> Locks;
+	Locks.emplace_back(RwLock::SharedLockScope(m_ProjectLock));
+	Locks.reserve(1 + m_Oplogs.size());
+	for (auto& Kv : m_Oplogs)
+	{
+		Locks.emplace_back(Kv.second->GetGcReferencerLock());
+	}
+	return Locks;
+}
+
 bool
 ProjectStore::Project::IsExpired(const RwLock::SharedLockScope&,
 								 const std::string&			  EntryName,
@@ -2221,11 +2290,13 @@ ProjectStore::ProjectStore(CidStore& Store, std::filesystem::path BasePath, GcMa
 	m_Gc.AddGcContributor(this);
 	m_Gc.AddGcStorage(this);
 	m_Gc.AddGcReferencer(*this);
+	m_Gc.AddGcReferenceLocker(*this);
 }
 
 ProjectStore::~ProjectStore()
 {
 	ZEN_INFO("closing project store at '{}'", m_ProjectBasePath);
+	m_Gc.RemoveGcReferenceLocker(*this);
 	m_Gc.RemoveGcReferencer(*this);
 	m_Gc.RemoveGcStorage(this);
 	m_Gc.RemoveGcContributor(this);
@@ -2559,6 +2630,13 @@ ProjectStore::NewProject(const std::filesystem::path& BasePath,
 	Prj->ProjectFilePath = ProjectFilePath;
 	Prj->Write();
 
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		if (m_CapturedProjects)
+		{
+			m_CapturedProjects->push_back(std::string(ProjectId));
+		}
+	});
+
 	return Prj;
 }
 
@@ -3753,6 +3831,48 @@ ProjectStore::AreDiskWritesAllowed() const
 	return (m_DiskWriteBlocker == nullptr || m_DiskWriteBlocker->AreDiskWritesAllowed());
 }
 
+void
+ProjectStore::EnableUpdateCapture()
+{
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		if (m_UpdateCaptureRefCounter == 0)
+		{
+			ZEN_ASSERT(!m_CapturedProjects);
+			m_CapturedProjects = std::make_unique<std::vector<std::string>>();
+		}
+		else
+		{
+			ZEN_ASSERT(m_CapturedProjects);
+		}
+		m_UpdateCaptureRefCounter++;
+	});
+}
+
+void
+ProjectStore::DisableUpdateCapture()
+{
+	m_UpdateCaptureLock.WithExclusiveLock([&]() {
+		ZEN_ASSERT(m_CapturedProjects);
+		ZEN_ASSERT(m_UpdateCaptureRefCounter > 0);
+		m_UpdateCaptureRefCounter--;
+		if (m_UpdateCaptureRefCounter == 0)
+		{
+			m_CapturedProjects.reset();
+		}
+	});
+}
+
+std::vector<std::string>
+ProjectStore::GetCapturedProjects()
+{
+	RwLock::SharedLockScope _(m_UpdateCaptureLock);
+	if (m_CapturedProjects)
+	{
+		return *m_CapturedProjects;
+	}
+	return {};
+}
+
 std::string
 ProjectStore::GetGcName(GcCtx&)
 {
@@ -3988,17 +4108,13 @@ ProjectStore::RemoveExpiredData(GcCtx& Ctx, GcStats& Stats)
 class ProjectStoreReferenceChecker : public GcReferenceChecker
 {
 public:
-	ProjectStoreReferenceChecker(ProjectStore::Oplog& Owner) : m_Oplog(Owner) {}
+	ProjectStoreReferenceChecker(ProjectStore& InProjectStore) : m_ProjectStore(InProjectStore) { m_ProjectStore.EnableUpdateCapture(); }
 
 	virtual ~ProjectStoreReferenceChecker()
 	{
 		try
 		{
-			m_OplogLock.reset();
-			if (m_OplogCaptureEnabled)
-			{
-				m_Oplog.DisableUpdateCapture();
-			}
+			m_ProjectStore.DisableUpdateCapture();
 		}
 		catch (const std::exception& Ex)
 		{
@@ -4006,42 +4122,190 @@ public:
 		}
 	}
 
-	virtual std::string GetGcName(GcCtx&) override { return fmt::format("oplog: '{}'", m_Oplog.m_BasePath); }
+	virtual std::string GetGcName(GcCtx&) override { return "projectstore"; }
+	virtual void		PreCache(GcCtx&) override {}
 
-	virtual void PreCache(GcCtx& Ctx) override
+	virtual void UpdateLockedState(GcCtx& Ctx) override
 	{
-		ZEN_TRACE_CPU("Store::PreCache");
+		ZEN_TRACE_CPU("Store::UpdateLockedState");
+
+		Stopwatch Timer;
+
+		std::vector<ProjectStore::Oplog*> AddedOplogs;
 
-		Stopwatch  Timer;
 		const auto _ = MakeGuard([&] {
 			if (!Ctx.Settings.Verbose)
 			{
 				return;
 			}
-			ZEN_INFO("GCV2: projectstore [PRECACHE] '{}': precached {} references in {} from {}/{}",
-					 m_Oplog.m_BasePath,
+			ZEN_INFO("GCV2: projectstore [LOCKSTATE] '{}': found {} references in {} in {} new oplogs",
+					 "projectstore",
 					 m_References.size(),
 					 NiceTimeSpanMs(Timer.GetElapsedTimeMs()),
-					 m_Oplog.m_OuterProject->Identifier,
-					 m_Oplog.OplogId());
+					 AddedOplogs.size());
+		});
+
+		std::vector<std::string> AddedProjects = m_ProjectStore.GetCapturedProjects();
+		for (const std::string& AddedProject : AddedProjects)
+		{
+			if (auto It = m_ProjectStore.m_Projects.find(AddedProject); It != m_ProjectStore.m_Projects.end())
+			{
+				ProjectStore::Project& Project = *It->second;
+				for (auto& OplogPair : Project.m_Oplogs)
+				{
+					ProjectStore::Oplog* Oplog = OplogPair.second.get();
+					AddedOplogs.push_back(Oplog);
+				}
+			}
+		}
+		for (auto& ProjectPair : m_ProjectStore.m_Projects)
+		{
+			ProjectStore::Project&	 Project = *ProjectPair.second;
+			std::vector<std::string> AddedOplogNames(Project.GetCapturedOplogs());
+			for (const std::string& OplogName : AddedOplogNames)
+			{
+				if (auto It = Project.m_Oplogs.find(OplogName); It != Project.m_Oplogs.end())
+				{
+					ProjectStore::Oplog* Oplog = It->second.get();
+					AddedOplogs.push_back(Oplog);
+				}
+			}
+		}
+
+		for (ProjectStore::Oplog* Oplog : AddedOplogs)
+		{
+			size_t BaseReferenceCount = m_References.size();
+
+			Stopwatch  InnerTimer;
+			const auto __ = MakeGuard([&] {
+				if (!Ctx.Settings.Verbose)
+				{
+					return;
+				}
+				ZEN_INFO("GCV2: projectstore [LOCKSTATE] '{}': found {} references in {} from {}",
+						 Oplog->m_BasePath,
+						 m_References.size() - BaseReferenceCount,
+						 NiceTimeSpanMs(InnerTimer.GetElapsedTimeMs()),
+						 Oplog->OplogId());
+			});
+
+			Oplog->IterateOplogLocked([&](const CbObjectView& UpdateOp) -> bool {
+				UpdateOp.IterateAttachments([&](CbFieldView Visitor) { m_References.emplace_back(Visitor.AsAttachment()); });
+				return true;
+			});
+		}
+	}
+
+	virtual void RemoveUsedReferencesFromSet(GcCtx& Ctx, HashSet& IoCids) override
+	{
+		ZEN_TRACE_CPU("Store::RemoveUsedReferencesFromSet");
+
+		size_t	   InitialCount = IoCids.size();
+		Stopwatch  Timer;
+		const auto _ = MakeGuard([&] {
+			if (!Ctx.Settings.Verbose)
+			{
+				return;
+			}
+			ZEN_INFO("GCV2: projectstore [FILTER REFERENCES] '{}': filtered out {} used references out of {} in {}",
+					 "projectstore",
+					 InitialCount - IoCids.size(),
+					 InitialCount,
+					 NiceTimeSpanMs(Timer.GetElapsedTimeMs()));
 		});
 
-		m_Oplog.EnableUpdateCapture();
-		m_OplogCaptureEnabled = true;
+		for (const IoHash& ReferenceHash : m_References)
+		{
+			if (IoCids.erase(ReferenceHash) == 1)
+			{
+				if (IoCids.empty())
+				{
+					return;
+				}
+			}
+		}
+	}
 
-		RwLock::SharedLockScope __(m_Oplog.m_OplogLock);
-		if (Ctx.IsCancelledFlag)
+private:
+	ProjectStore&		m_ProjectStore;
+	std::vector<IoHash> m_References;
+};
+
+class ProjectStoreOplogReferenceChecker : public GcReferenceChecker
+{
+public:
+	ProjectStoreOplogReferenceChecker(ProjectStore& InProjectStore, Ref<ProjectStore::Project> InProject, std::string_view InOplog)
+	: m_ProjectStore(InProjectStore)
+	, m_Project(InProject)
+	, m_OplogName(InOplog)
+	{
+		m_Project->EnableUpdateCapture();
+	}
+
+	virtual ~ProjectStoreOplogReferenceChecker()
+	{
+		try
 		{
-			return;
+			m_Project->DisableUpdateCapture();
+			if (m_OplogCaptureEnabled)
+			{
+				ZEN_ASSERT(m_Oplog);
+				m_Oplog->DisableUpdateCapture();
+			}
+		}
+		catch (const std::exception& Ex)
+		{
+			ZEN_ERROR("~ProjectStoreOplogReferenceChecker threw exception: '{}'", Ex.what());
 		}
-		m_Oplog.IterateOplog([&](CbObjectView Op) {
-			Op.IterateAttachments([&](CbFieldView Visitor) { m_References.emplace_back(Visitor.AsAttachment()); });
+	}
+
+	virtual std::string GetGcName(GcCtx&) override { return fmt::format("oplog: '{}/{}'", m_Project->Identifier, m_OplogName); }
+
+	virtual void PreCache(GcCtx& Ctx) override
+	{
+		ZEN_TRACE_CPU("Store::Oplog::PreCache");
+
+		Stopwatch  Timer;
+		const auto _ = MakeGuard([&] {
+			if (!Ctx.Settings.Verbose)
+			{
+				return;
+			}
+			if (m_Oplog)
+			{
+				ZEN_INFO("GCV2: projectstore [PRECACHE] '{}': precached {} references in {} from {}/{}",
+						 m_Oplog->m_BasePath,
+						 m_References.size(),
+						 NiceTimeSpanMs(Timer.GetElapsedTimeMs()),
+						 m_Project->Identifier,
+						 m_Oplog->OplogId());
+			}
 		});
+
+		if (auto It = m_Project->m_Oplogs.find(m_OplogName); It != m_Project->m_Oplogs.end())
+		{
+			m_Oplog = It->second.get();
+			m_Oplog->EnableUpdateCapture();
+			m_OplogCaptureEnabled = true;
+
+			RwLock::SharedLockScope __(m_Oplog->m_OplogLock);
+			if (Ctx.IsCancelledFlag)
+			{
+				return;
+			}
+			m_Oplog->IterateOplog([&](CbObjectView Op) {
+				Op.IterateAttachments([&](CbFieldView Visitor) { m_References.emplace_back(Visitor.AsAttachment()); });
+			});
+		}
 	}
 
-	virtual void LockState(GcCtx& Ctx) override
+	virtual void UpdateLockedState(GcCtx& Ctx) override
 	{
-		ZEN_TRACE_CPU("Store::LockState");
+		ZEN_TRACE_CPU("Store::Oplog::UpdateLockedState");
+		if (!m_Oplog)
+		{
+			return;
+		}
 
 		Stopwatch  Timer;
 		const auto _ = MakeGuard([&] {
@@ -4050,25 +4314,28 @@ public:
 				return;
 			}
 			ZEN_INFO("GCV2: projectstore [LOCKSTATE] '{}': found {} references in {} from {}/{}",
-					 m_Oplog.m_BasePath,
+					 m_Oplog->m_BasePath,
 					 m_References.size(),
 					 NiceTimeSpanMs(Timer.GetElapsedTimeMs()),
-					 m_Oplog.m_OuterProject->Identifier,
-					 m_Oplog.OplogId());
+					 m_Project->Identifier,
+					 m_Oplog->OplogId());
 		});
 
-		m_OplogLock = std::make_unique<RwLock::SharedLockScope>(m_Oplog.m_OplogLock);
-		m_Oplog.IterateUpdatedLSNs(*m_OplogLock, [&](const CbObjectView& UpdateOp) -> bool {
+		m_Oplog->IterateCapturedLSNs([&](const CbObjectView& UpdateOp) -> bool {
 			UpdateOp.IterateAttachments([&](CbFieldView Visitor) { m_References.emplace_back(Visitor.AsAttachment()); });
 			return true;
 		});
+		std::vector<IoHash> AddedAttachments = m_Oplog->GetCapturedAttachments();
+		m_References.insert(m_References.end(), AddedAttachments.begin(), AddedAttachments.end());
 	}
 
 	virtual void RemoveUsedReferencesFromSet(GcCtx& Ctx, HashSet& IoCids) override
 	{
-		ZEN_TRACE_CPU("Store::RemoveUsedReferencesFromSet");
-
-		ZEN_ASSERT(m_OplogLock);
+		ZEN_TRACE_CPU("Store::Oplog::RemoveUsedReferencesFromSet");
+		if (!m_Oplog)
+		{
+			return;
+		}
 
 		size_t	   InitialCount = IoCids.size();
 		Stopwatch  Timer;
@@ -4078,7 +4345,7 @@ public:
 				return;
 			}
 			ZEN_INFO("GCV2: projectstore [FILTER REFERENCES] '{}': filtered out {} used references out of {} in {}",
-					 m_Oplog.m_BasePath,
+					 m_Oplog->m_BasePath,
 					 InitialCount - IoCids.size(),
 					 InitialCount,
 					 NiceTimeSpanMs(Timer.GetElapsedTimeMs()));
@@ -4094,21 +4361,13 @@ public:
 				}
 			}
 		}
-		m_Oplog.IterateAddedAttachments(*m_OplogLock, [&](const IoHash& RawHash) -> bool {
-			if (IoCids.erase(RawHash) == 1)
-			{
-				if (IoCids.empty())
-				{
-					return false;
-				}
-			}
-			return true;
-		});
 	}
-	ProjectStore::Oplog&					 m_Oplog;
-	std::unique_ptr<RwLock::SharedLockScope> m_OplogLock;
-	std::vector<IoHash>						 m_References;
-	bool									 m_OplogCaptureEnabled = false;
+	ProjectStore&			   m_ProjectStore;
+	Ref<ProjectStore::Project> m_Project;
+	std::string				   m_OplogName;
+	ProjectStore::Oplog*	   m_Oplog = nullptr;
+	std::vector<IoHash>		   m_References;
+	bool					   m_OplogCaptureEnabled = false;
 };
 
 std::vector<GcReferenceChecker*>
@@ -4135,6 +4394,8 @@ ProjectStore::CreateReferenceCheckers(GcCtx& Ctx)
 	DiscoverProjects();
 
 	std::vector<Ref<ProjectStore::Project>> Projects;
+	std::vector<GcReferenceChecker*>		Checkers;
+	Checkers.emplace_back(new ProjectStoreReferenceChecker(*this));
 	{
 		RwLock::SharedLockScope Lock(m_ProjectsLock);
 		Projects.reserve(m_Projects.size());
@@ -4145,21 +4406,15 @@ ProjectStore::CreateReferenceCheckers(GcCtx& Ctx)
 		}
 	}
 	ProjectCount += Projects.size();
-	std::vector<GcReferenceChecker*> Checkers;
 	try
 	{
 		for (const Ref<ProjectStore::Project>& Project : Projects)
 		{
 			std::vector<std::string> OpLogs = Project->ScanForOplogs();
-			Checkers.reserve(OpLogs.size());
+			Checkers.reserve(Checkers.size() + OpLogs.size());
 			for (const std::string& OpLogId : OpLogs)
 			{
-				ProjectStore::Oplog* Oplog = Project->OpenOplog(OpLogId);
-				if (Oplog == nullptr)
-				{
-					continue;
-				}
-				Checkers.emplace_back(new ProjectStoreReferenceChecker(*Oplog));
+				Checkers.emplace_back(new ProjectStoreOplogReferenceChecker(*this, Project, OpLogId));
 				OplogCount++;
 			}
 		}
@@ -4177,6 +4432,22 @@ ProjectStore::CreateReferenceCheckers(GcCtx& Ctx)
 	return Checkers;
 }
 
+std::vector<RwLock::SharedLockScope>
+ProjectStore::LockState(GcCtx&)
+{
+	std::vector<RwLock::SharedLockScope> Locks;
+	Locks.emplace_back(RwLock::SharedLockScope(m_ProjectsLock));
+	for (auto& ProjectIt : m_Projects)
+	{
+		std::vector<RwLock::SharedLockScope> ProjectLocks = ProjectIt.second->GetGcReferencerLocks();
+		for (auto It = std::make_move_iterator(ProjectLocks.begin()); It != std::make_move_iterator(ProjectLocks.end()); It++)
+		{
+			Locks.emplace_back(std::move(*It));
+		}
+	}
+	return Locks;
+}
+
 //////////////////////////////////////////////////////////////////////////
 
 #if ZEN_WITH_TESTS