The logic of Message internals

Question

I am trying to figure out the logic of Message behavior.

Consider evaluation of the following:

On[]
Sin[1,1]

After eva

Answer 1

It seems that I have found one way to achieve with built-in function Message what I want:

Unprotect[Message];
Message[_, HoldForm[Block[List[$MyMagicalTag$, ___], _]], _] := Null;
Message[args___] /; 
   Block[{$MyMagicalTag$, Message}, Not@TrueQ[inMsg]] := 
  Block[{$MyMagicalTag$, inMsg = True, lastargs = HoldComplete[args]},
    Message[args]];
Message[args___] /; 
   Block[{$MyMagicalTag$, 
     Message}, (inMsg && (HoldComplete[args] =!= lastargs))] := Null;
Protect[Message];

Now things work as expected:

In[6]:= On[]
In[7]:= Sin[1,1]//AbsoluteTiming
During evaluation of In[7]:= Message::trace: Message[Sin::argx,Sin,2] --> Block[{$MyMagicalTag$,inMsg=True,lastargs=HoldComplete[Sin::argx,Sin,2]},Message[Sin::argx,Sin,2]]. >>
During evaluation of In[7]:= Sin::argx: Sin called with 2 arguments; 1 argument is expected. >>
During evaluation of In[7]:= AbsoluteTiming::trace: AbsoluteTiming[Sin[1,1]] --> {0.1502160,Sin[1,1]}. >>
Out[7]= {0.1502160,Sin[1,1]}

The only problem with the above is that CPU load is still high as you can see from the timings.

Other tested cases also work correctly:

In[8]:= 1+1//AbsoluteTiming
During evaluation of In[8]:= Plus::trace: 1+1 --> 2. >>
During evaluation of In[8]:= AbsoluteTiming::trace: AbsoluteTiming[1+1] --> {0.0400576,2}. >>
Out[8]= {0.0400576,2}

Thanks to Mr.Wizard for his help.

Answer 2

I am not understanding why it is necessary to turn on all the messages with On. Can you not only activate the subset you need. The reference page of On in "More Information" section lists various categories which you might find useful. In case you choose to proceed as stated, you can suppress trace messages by explicitly turning them off right after On[]:

On[]; Off[General::trace];
Sin[1, 1]

This outputs only two messages. Hence 830 of the messages you see are ::trace messages and originate from execution of some top-level code which is not necessarily message related, might be typesetting...