Add slow commands as phosphor instant traces

We should expand on this to show to entire execution time of the
command. For now, however, this will do.

Change-Id: Iac56095c01a00a07111eeca3b1a7a62a68e73922
Reviewed-on: http://review.couchbase.org/82915
Reviewed-by: Dave Rigby <[email protected]>
Tested-by: Build Bot <[email protected]>

Author: olivermd

daemon/connection_mcbp.cc

@@ -22,6 +22,7 @@
 #include "mc_time.h"
 
 #include <mcbp/mcbp.h>
+#include <phosphor/phosphor.h>
 #include <platform/cb_malloc.h>
 #include <platform/checked_snprintf.h>
 #include <platform/strerror.h>
@@ -1086,6 +1087,7 @@ void McbpConnection::maybeLogSlowCommand(
             }
         }
 
+        TRACE_INSTANT2("memcached/slow", "Slow cmd", "opcode", cmd, "connection_id", getId());
         LOG_WARNING(NULL,
                     "%u: Slow %s operation on connection: %s (%s)%s"
                     " opaque:0x%08x",