Rework of runtime interface (#1498)

Also have special error handling for when branches are invalid and
ENOENT would be returned for getattr and readdir so users understand
what is going on and the runtime interface can still be used to fix
the problem.

src/gidcache.cpp

@@ -16,6 +16,8 @@
 
 #include "gidcache.hpp"
 
+#include "syslog.hpp"
+
 #include <grp.h>
 #include <pwd.h>
 #include <stdlib.h>
@@ -130,27 +132,47 @@ GIDCache::initgroups(const uid_t uid_,
 void
 GIDCache::invalidate_all()
 {
+  size_t size;
+
+  size = _records.size();
   _records.visit_all([](auto &x)
   {
     x.second.last_update = 0;
   });
+
+  SysLog::info("gid cache invalidated, {} entries",size);
 }
 
 void
 GIDCache::clear_all()
 {
+  size_t size;
+
+  size = _records.size();
   _records.clear();
+
+  SysLog::info("gid cache cleared, {} entries",size);
 }
 
 void
 GIDCache::clear_unused()
 {
+  int erased = 0;
   time_t now = ::time(NULL);
   auto erase_func =
-    [=](auto &x)
+    [now,&erased](auto &x)
     {
-      return ((now - x.second.last_update) > GIDCache::remove_timeout);
+      bool should_erase;
+      time_t time_delta;
+
+      time_delta = (now - x.second.last_update);
+      should_erase = (time_delta > GIDCache::remove_timeout);
+      erased += should_erase;
+
+      return should_erase;
     };
 
   _records.erase_if(erase_func);
+
+  SysLog::info("cleared {} unused gid cache entries",erased);
 }