4 files changed, 99 insertions, 24 deletions

diff --git a/zenstore/include/zenstore/CAS.h b/zenstore/include/zenstore/CAS.h
index 86e7e78d9..5b508baa0 100644
--- a/zenstore/include/zenstore/CAS.h
+++ b/zenstore/include/zenstore/CAS.h
@@ -11,6 +11,7 @@
 #include <zencore/timer.h>
 
 #include <atomic>
+#include <concepts>
 #include <filesystem>
 #include <functional>
 #include <memory>
@@ -19,6 +20,9 @@
 
 namespace zen {
 
+class GcContext;
+class CasGc;
+
 struct CasStoreConfiguration
 {
 	// Root directory for CAS store
@@ -45,29 +49,22 @@ public:
 	inline [[nodiscard]] bool	IsEmpty() const { return m_ChunkSet.empty(); }
 	inline [[nodiscard]] size_t GetSize() const { return m_ChunkSet.size(); }
 
+	inline void FilterChunks(std::span<const IoHash> Candidates, std::invocable<const IoHash&> auto MatchFunc)
+	{
+		for (const IoHash& Candidate : Candidates)
+		{
+			if (ContainsChunk(Candidate))
+			{
+				MatchFunc(Candidate);
+			}
+		}
+	}
+
 private:
 	// Q: should we protect this with a lock, or is that a higher level concern?
 	std::unordered_set<IoHash> m_ChunkSet;
 };
 
-/** Garbage Collection context object
- */
-
-class GcContext
-{
-public:
-	GcContext();
-	~GcContext();
-
-	void ContributeCids(std::span<const IoHash> Cid);
-	void ContributeCas(std::span<const IoHash> Hash);
-
-private:
-	struct GcState;
-
-	std::unique_ptr<GcState> m_State;
-};
-
 /** Context object for data scrubbing
  *
  * Data scrubbing is when we traverse stored data to validate it and
@@ -116,13 +113,14 @@ public:
 	virtual void		 FilterChunks(CasChunkSet& InOutChunks)				 = 0;
 	virtual void		 Flush()											 = 0;
 	virtual void		 Scrub(ScrubContext& Ctx)							 = 0;
+	virtual void		 GarbageCollect(GcContext& GcCtx)					 = 0;
 
 protected:
 	CasStoreConfiguration m_Config;
 	uint64_t			  m_LastScrubTime = 0;
 };
 
-ZENCORE_API CasStore* CreateCasStore();
+ZENCORE_API CasStore* CreateCasStore(CasGc& Gc);
 
 void CAS_forcelink();
 
diff --git a/zenstore/include/zenstore/caslog.h b/zenstore/include/zenstore/caslog.h
index 00b987383..065a74b25 100644
--- a/zenstore/include/zenstore/caslog.h
+++ b/zenstore/include/zenstore/caslog.h
@@ -57,6 +57,8 @@ template<typename T>
 class TCasLogFile : public CasLogFile
 {
 public:
+	void Open(std::filesystem::path FileName, bool IsCreate) { CasLogFile::Open(FileName, sizeof(T), IsCreate); }
+
 	// This should be called before the Replay() is called to do some basic sanity checking
 	bool Initialize() { return true; }
 
@@ -76,7 +78,6 @@ public:
 
 		CasLogFile::Append(&Record, sizeof Record);
 	}
-	void Open(std::filesystem::path FileName, bool IsCreate) { CasLogFile::Open(FileName, sizeof(T), IsCreate); }
 };
 
 }  // namespace zen
diff --git a/zenstore/include/zenstore/cidstore.h b/zenstore/include/zenstore/cidstore.h
index 5f567e7fc..acfedbc64 100644
--- a/zenstore/include/zenstore/cidstore.h
+++ b/zenstore/include/zenstore/cidstore.h
@@ -4,10 +4,13 @@
 
 #include "zenstore.h"
 
-#include <tsl/robin_map.h>
 #include <zencore/iohash.h>
 #include <zenstore/CAS.h>
 
+ZEN_THIRD_PARTY_INCLUDES_START
+#include <tsl/robin_map.h>
+ZEN_THIRD_PARTY_INCLUDES_END
+
 namespace std::filesystem {
 class path;
 }
diff --git a/zenstore/include/zenstore/gc.h b/zenstore/include/zenstore/gc.h
index 055843547..ef62158ce 100644
--- a/zenstore/include/zenstore/gc.h
+++ b/zenstore/include/zenstore/gc.h
@@ -3,26 +3,99 @@
 #pragma once
 
 #include <zencore/iohash.h>
+#include <zencore/thread.h>
 
 #include <span>
 
+#define ZEN_USE_REF_TRACKING 0	// This is not currently functional
+
 namespace zen {
 
 class CasStore;
+class CasGc;
 struct IoHash;
 
+/** Garbage Collection context object
+ */
+
+class GcContext
+{
+public:
+	GcContext();
+	~GcContext();
+
+	void ContributeCids(std::span<const IoHash> Cid);
+	void ContributeCas(std::span<const IoHash> Hash);
+
+	void FilterCids(std::span<const IoHash> Cid, std::function<void(const IoHash&)> KeepFunc);
+	void FilterCas(std::span<const IoHash> Cas, std::function<void(const IoHash&)> KeepFunc);
+
+private:
+	struct GcState;
+
+	std::unique_ptr<GcState> m_State;
+};
+
+/** GC root contributor
+
+	Higher level data structures provide roots for the garbage collector,
+	which ultimately determine what is garbage and what data we need to
+	retain.
+
+ */
+
+class GcContributor
+{
+public:
+	GcContributor(CasGc& Gc);
+	~GcContributor();
+
+	virtual void GatherReferences(GcContext& GcCtx) = 0;
+
+protected:
+	CasGc& m_Gc;
+};
+
+/** GC storage provider
+ */
+
+class GcStorage
+{
+public:
+	GcStorage(CasGc& Gc);
+	~GcStorage();
+
+	virtual void CollectGarbage(GcContext& GcCtrx) = 0;
+
+private:
+	CasGc& m_Gc;
+};
+
+/** GC orchestrator
+ */
+
 class CasGc
 {
 public:
-	CasGc(CasStore& Store);
+	CasGc();
 	~CasGc();
 
+	void AddGcContributor(GcContributor* Contributor);
+	void RemoveGcContributor(GcContributor* Contributor);
+
+	void AddGcStorage(GcStorage* Contributor);
+	void RemoveGcStorage(GcStorage* Contributor);
+
 	void CollectGarbage();
 
-	void OnNewReferences(std::span<IoHash> Hashes);
+	void OnNewCidReferences(std::span<IoHash> Hashes);
+	void OnCommittedCidReferences(std::span<IoHash> Hashes);
+	void OnDroppedCidReferences(std::span<IoHash> Hashes);
 
 private:
-	CasStore& m_CasStore;
+	RwLock						m_Lock;
+	std::vector<GcContributor*> m_GcContribs;
+	std::vector<GcStorage*>		m_GcStorage;
 };
 
 }  // namespace zen