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, 9 insertions, 12 deletions

diff --git a/src/zenhttp/include/zenhttp/httpclient.h b/src/zenhttp/include/zenhttp/httpclient.h
index ae1e2bf20..9de5c7cce 100644
--- a/src/zenhttp/include/zenhttp/httpclient.h
+++ b/src/zenhttp/include/zenhttp/httpclient.h
@@ -5,16 +5,13 @@
 #include "zenhttp.h"
 
 #include <zencore/iobuffer.h>
+#include <zencore/logbase.h>
 #include <zencore/uid.h>
 #include <zenhttp/httpcommon.h>
 
 #include <optional>
 #include <unordered_map>
 
-namespace spdlog {
-class logger;
-}  // namespace spdlog
-
 namespace zen {
 
 class CbPackage;
@@ -148,13 +145,13 @@ public:
 		return std::make_pair("Accept", MapContentTypeToString(ContentType));
 	}
 
-	spdlog::logger&	 Logger() { return m_Log; }
+	LoggerRef		 Logger() { return m_Log; }
 	std::string_view GetBaseUri() const { return m_BaseUri; }
 
 private:
 	struct Impl;
 
-	spdlog::logger&			 m_Log;
+	LoggerRef				 m_Log;
 	std::string				 m_BaseUri;
 	std::string				 m_SessionId;
 	const HttpClientSettings m_ConnectionSettings;
diff --git a/src/zenhttp/include/zenhttp/httpstats.h b/src/zenhttp/include/zenhttp/httpstats.h
index 4a1cdcb20..e6fea6765 100644
--- a/src/zenhttp/include/zenhttp/httpstats.h
+++ b/src/zenhttp/include/zenhttp/httpstats.h
@@ -21,13 +21,13 @@ public:
 	virtual void		UnregisterHandler(std::string_view Id, IHttpStatsProvider& Provider) override;
 
 private:
-	spdlog::logger&	  m_Log;
+	LoggerRef		  m_Log;
 	HttpRequestRouter m_Router;
 
-	inline spdlog::logger& Log() { return m_Log; }
+	inline LoggerRef Log() { return m_Log; }
 
 	RwLock									   m_Lock;
 	std::map<std::string, IHttpStatsProvider*> m_Providers;
 };
 
-}  // namespace zen
\ No newline at end of file
+}  // namespace zen
diff --git a/src/zenhttp/include/zenhttp/httpstatus.h b/src/zenhttp/include/zenhttp/httpstatus.h
index b04e45324..093f62481 100644
--- a/src/zenhttp/include/zenhttp/httpstatus.h
+++ b/src/zenhttp/include/zenhttp/httpstatus.h
@@ -26,13 +26,13 @@ public:
 	void				UnregisterHandler(std::string_view Id, IHttpStatusProvider& Provider);
 
 private:
-	spdlog::logger&	  m_Log;
+	LoggerRef		  m_Log;
 	HttpRequestRouter m_Router;
 
 	RwLock										m_Lock;
 	std::map<std::string, IHttpStatusProvider*> m_Providers;
 
-	inline spdlog::logger& Log() { return m_Log; }
+	inline LoggerRef Log() { return m_Log; }
 };
 
-}  // namespace zen
\ No newline at end of file
+}  // namespace zen