Add timer:tc/1 which measures elapsed time for a fun/0

Also removes the 'catch' from timer:tc functions which masked errors
in measuring code.

3 files changed, 53 insertions, 11 deletions

diff --git a/lib/stdlib/doc/src/timer.xml b/lib/stdlib/doc/src/timer.xml
index cae655f801..0baeff1db3 100644
--- a/lib/stdlib/doc/src/timer.xml
+++ b/lib/stdlib/doc/src/timer.xml
@@ -203,6 +203,7 @@
     <func>
       <name>tc(Module, Function, Arguments) -> {Time, Value}</name>
       <name>tc(Fun, Arguments) -> {Time, Value}</name>
+      <name>tc(Fun) -> {Time, Value}</name>
       <fsummary>Measure the real time it takes to evaluate <c>apply(Module,
       Function, Arguments)</c> or <c>apply(Fun, Arguments)</c></fsummary>
       <type>
@@ -218,7 +219,7 @@
           <tag><c>tc/3</c></tag>
           <item>
             <p>Evaluates <c>apply(Module, Function, Arguments)</c> and measures
-              the elapsed real time as reported by <c>now/0</c>.
+              the elapsed real time as reported by <c>os:timestamp/0</c>.
               Returns <c>{Time, Value}</c>, where
               <c>Time</c> is the elapsed real time in <em>microseconds</em>,
               and <c>Value</c> is what is returned from the apply.</p>
@@ -228,6 +229,11 @@
             <p>Evaluates <c>apply(Fun, Arguments)</c>. Otherwise works
             like <c>tc/3</c>.</p>
           </item>
+          <tag><c>tc/1</c></tag>
+          <item>
+            <p>Evaluates <c>Fun()</c>. Otherwise works like <c>tc/2</c>.</p>
+          </item>
+
         </taglist>
       </desc>
     </func>
diff --git a/lib/stdlib/src/timer.erl b/lib/stdlib/src/timer.erl
index b456c5d6c1..78e897b877 100644
--- a/lib/stdlib/src/timer.erl
+++ b/lib/stdlib/src/timer.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -22,7 +22,7 @@
 	 send_after/3, send_after/2,
 	 exit_after/3, exit_after/2, kill_after/2, kill_after/1,
 	 apply_interval/4, send_interval/3, send_interval/2,
-	 cancel/1, sleep/1, tc/2, tc/3, now_diff/2,
+	 cancel/1, sleep/1, tc/1, tc/2, tc/3, now_diff/2,
 	 seconds/1, minutes/1, hours/1, hms/3]).
 
 -export([start_link/0, start/0, 
@@ -101,15 +101,24 @@ sleep(T) ->
     after T -> ok
     end.
 
+%%
+%% Measure the execution time (in microseconds) for Fun().
+%%
+-spec tc(function()) -> {time(), term()}.
+tc(F) ->
+    Before = os:timestamp(),
+    Val = F(),
+    After = os:timestamp(),
+    {now_diff(After, Before), Val}.
 
 %%
 %% Measure the execution time (in microseconds) for Fun(Args).
 %%
 -spec tc(function(), [_]) -> {time(), term()}.
 tc(F, A) ->
-    Before = erlang:now(),
-    Val = (catch apply(F, A)),
-    After = erlang:now(),
+    Before = os:timestamp(),
+    Val = apply(F, A),
+    After = os:timestamp(),
     {now_diff(After, Before), Val}.
 
 %%
@@ -117,9 +126,9 @@ tc(F, A) ->
 %%
 -spec tc(atom(), atom(), [term()]) -> {time(), term()}.
 tc(M, F, A) ->
-    Before = erlang:now(),
-    Val = (catch apply(M, F, A)),
-    After = erlang:now(),
+    Before = os:timestamp(),
+    Val = apply(M, F, A),
+    After = os:timestamp(),
     {now_diff(After, Before), Val}.
 
 %%
diff --git a/lib/stdlib/test/timer_simple_SUITE.erl b/lib/stdlib/test/timer_simple_SUITE.erl
index 852afa1a4d..dc751aad16 100644
--- a/lib/stdlib/test/timer_simple_SUITE.erl
+++ b/lib/stdlib/test/timer_simple_SUITE.erl
@@ -229,7 +229,7 @@ cancel2(Config) when is_list(Config) ->
 tc(doc) -> "Test sleep/1 and tc/3.";
 tc(suite) -> [];
 tc(Config) when is_list(Config) ->
-    % This should both sleep and tc/3
+    %% This should test both sleep and tc/3
     ?line {Res1, ok} = timer:tc(timer, sleep, [500]),
     ?line ok = 	if
 		    Res1 < 500*1000 -> {too_early, Res1}; % Too early
@@ -237,13 +237,40 @@ tc(Config) when is_list(Config) ->
 		    true -> ok
 		end,
 
-    % This should both sleep and tc/2
+    %% tc/2
     ?line {Res2, ok} = timer:tc(fun(T) -> timer:sleep(T) end, [500]),
     ?line ok = 	if
 		    Res2 < 500*1000 -> {too_early, Res2}; % Too early
 		    Res2 > 800*1000 -> {too_late, Res2};  % Too much time
 		    true -> ok
 		end,
+    
+    %% tc/1
+    ?line {Res3, ok} = timer:tc(fun() -> timer:sleep(500) end),
+    ?line ok = 	if
+    		    Res3 < 500*1000 -> {too_early, Res3}; % Too early
+    		    Res3 > 800*1000 -> {too_late, Res3};  % Too much time
+    		    true -> ok
+    		end,
+
+    %% Check that timer:tc don't catch errors
+    ?line ok = try timer:tc(erlang, exit, [foo]) 
+	       catch exit:foo -> ok
+	       end,
+    
+    ?line ok = try timer:tc(fun(Reason) -> 1 = Reason end, [foo]) 
+	       catch error:{badmatch,_} -> ok
+	       end,
+    
+    ?line ok = try timer:tc(fun() -> throw(foo) end) 
+	       catch foo -> ok
+	       end,
+    
+    %% Check that return values are propageted
+    Self = self(),
+    ?line {_, Self} = timer:tc(erlang, self, []),
+    ?line {_, Self} = timer:tc(fun(P) -> P end, [self()]),
+    ?line {_, Self} = timer:tc(fun() -> self() end),
 
     ?line Sec = timer:seconds(4),
     ?line Min = timer:minutes(4),