spdlog implementation hiding (#498)

this change aims to hide logging internals from client code, in order to make it easier to extend and take more control over the logging process in the future. 

As a bonus side effect, the generated code is much tighter (net delta around 2.5% on the resulting executable which includes lots of thirdparty code) and should take less time to compile and link.

Client usage via macros is pretty much unchanged. The main exposure client code had to spdlog internals before was the use of custom loggers per subsystem, where it would be common to have `spdlog::logger` references to keep a reference to a logger within a class. This is now replaced by `zen::LoggerRef` which currently simply encapsulates an actual `spdlog::logger` instance, but this is intended to be an implementation detail which will change in the future.

The way the change works is that we now handle any formatting of log messages in the zencore logging subsystem instead of relying on `spdlog` to manage this. We use the `fmt` library to do the formatting which means the client usage is identical to using `spdlog`. The formatted message is then forwarded onto any sinks etc which are still implememted via `spdlog`.

3 files changed, 24 insertions, 34 deletions

diff --git a/src/zenstore/compactcas.h b/src/zenstore/compactcas.h
index 9f3aa6b07..3ed883801 100644
--- a/src/zenstore/compactcas.h
+++ b/src/zenstore/compactcas.h
@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include <zencore/logbase.h>
 #include <zencore/zencore.h>
 #include <zenstore/blockstore.h>
 #include <zenstore/caslog.h>
@@ -16,10 +17,6 @@ ZEN_THIRD_PARTY_INCLUDES_START
 #include <tsl/robin_map.h>
 ZEN_THIRD_PARTY_INCLUDES_END
 
-namespace spdlog {
-class logger;
-}
-
 namespace zen {
 
 //////////////////////////////////////////////////////////////////////////
@@ -82,9 +79,9 @@ private:
 	void				   OpenContainer(bool IsNewStore);
 	void				   CompactIndex(RwLock::ExclusiveLockScope&);
 
-	spdlog::logger& Log() { return m_Log; }
+	LoggerRef Log() { return m_Log; }
 
-	spdlog::logger&				   m_Log;
+	LoggerRef					   m_Log;
 	GcManager&					   m_Gc;
 	std::filesystem::path		   m_RootDirectory;
 	uint64_t					   m_PayloadAlignment = 1u << 4;
diff --git a/src/zenstore/filecas.h b/src/zenstore/filecas.h
index c39a39bb7..cb1347580 100644
--- a/src/zenstore/filecas.h
+++ b/src/zenstore/filecas.h
@@ -16,10 +16,6 @@
 #include <atomic>
 #include <functional>
 
-namespace spdlog {
-class logger;
-}
-
 namespace zen {
 
 class BasicFile;
@@ -48,10 +44,10 @@ struct FileCasStrategy final : public GcStorage, public GcReferenceStore
 	virtual GcReferencePruner* CreateReferencePruner(GcCtx& Ctx, GcReferenceStoreStats& Stats) override;
 
 private:
-	void			MakeIndexSnapshot();
-	uint64_t		ReadIndexFile(const std::filesystem::path& IndexPath, uint32_t& OutVersion);
-	uint64_t		ReadLog(const std::filesystem::path& LogPath, uint64_t LogPosition);
-	spdlog::logger& Log() { return m_Log; }
+	void	  MakeIndexSnapshot();
+	uint64_t  ReadIndexFile(const std::filesystem::path& IndexPath, uint32_t& OutVersion);
+	uint64_t  ReadLog(const std::filesystem::path& LogPath, uint64_t LogPosition);
+	LoggerRef Log() { return m_Log; }
 
 	struct IndexEntry
 	{
@@ -61,7 +57,7 @@ private:
 
 	CasStore::InsertResult InsertChunkData(const void* ChunkData, size_t ChunkSize, const IoHash& ChunkHash);
 
-	spdlog::logger&		  m_Log;
+	LoggerRef			  m_Log;
 	GcManager&			  m_Gc;
 	std::filesystem::path m_RootDirectory;
 	RwLock				  m_Lock;
diff --git a/src/zenstore/include/zenstore/gc.h b/src/zenstore/include/zenstore/gc.h
index 1b9929216..409c9b4d6 100644
--- a/src/zenstore/include/zenstore/gc.h
+++ b/src/zenstore/include/zenstore/gc.h
@@ -3,6 +3,7 @@
 #pragma once
 
 #include <zencore/iohash.h>
+#include <zencore/logbase.h>
 #include <zencore/thread.h>
 #include <zenstore/caslog.h>
 #include <zenstore/scrubcontext.h>
@@ -24,10 +25,6 @@ ZEN_THIRD_PARTY_INCLUDES_START
 #include <tsl/robin_set.h>
 ZEN_THIRD_PARTY_INCLUDES_END
 
-namespace spdlog {
-class logger;
-}
-
 namespace zen {
 
 class CidStore;
@@ -360,8 +357,8 @@ public:
 	void					SetDiskWriteBlocker(const DiskWriteBlocker* Monitor) { m_DiskWriteBlocker = Monitor; }
 
 private:
-	spdlog::logger&				Log() { return m_Log; }
-	spdlog::logger&				m_Log;
+	LoggerRef					Log() { return m_Log; }
+	LoggerRef					m_Log;
 	mutable RwLock				m_Lock;
 	std::vector<GcContributor*> m_GcContribs;
 	std::vector<GcStorage*>		m_GcStorage;
@@ -483,19 +480,19 @@ public:
 	bool TriggerScrub(const TriggerScrubParams& Params);
 
 private:
-	void			SchedulerThread();
-	void			CollectGarbage(const GcClock::TimePoint& CacheExpireTime,
-								   const GcClock::TimePoint& ProjectStoreExpireTime,
-								   bool						 Delete,
-								   bool						 CollectSmallObjects,
-								   bool						 SkipCid,
-								   GcVersion				 UseGCVersion);
-	void			ScrubStorage(bool DoDelete, std::chrono::seconds TimeSlice);
-	spdlog::logger& Log() { return m_Log; }
-	virtual bool	AreDiskWritesAllowed() const override { return !m_AreDiskWritesBlocked.load(); }
-	DiskSpace		CheckDiskSpace();
-
-	spdlog::logger&	   m_Log;
+	void		 SchedulerThread();
+	void		 CollectGarbage(const GcClock::TimePoint& CacheExpireTime,
+								const GcClock::TimePoint& ProjectStoreExpireTime,
+								bool					  Delete,
+								bool					  CollectSmallObjects,
+								bool					  SkipCid,
+								GcVersion				  UseGCVersion);
+	void		 ScrubStorage(bool DoDelete, std::chrono::seconds TimeSlice);
+	LoggerRef	 Log() { return m_Log; }
+	virtual bool AreDiskWritesAllowed() const override { return !m_AreDiskWritesBlocked.load(); }
+	DiskSpace	 CheckDiskSpace();
+
+	LoggerRef		   m_Log;
 	GcManager&		   m_GcManager;
 	GcSchedulerConfig  m_Config;
 	GcClock::TimePoint m_LastGcTime{};