Add timer:tc/2 to measure the elapsed time of anonymous functions

Works like timer:tc/3 but for anonymous functions.

3 files changed, 44 insertions, 11 deletions

diff --git a/lib/stdlib/doc/src/timer.xml b/lib/stdlib/doc/src/timer.xml
index 0b6807dd6c..3d54047e35 100644
--- a/lib/stdlib/doc/src/timer.xml
+++ b/lib/stdlib/doc/src/timer.xml
@@ -202,18 +202,32 @@
     </func>
     <func>
       <name>tc(Module, Function, Arguments) -> {Time, Value}</name>
-      <fsummary>Measure the real time it takes to evaluate <c>apply(Module, Function, Arguments)</c></fsummary>
+      <name>tc(Fun, Arguments) -> {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>
         <v>Module = Function = atom()</v>
+        <v>Fun = fun()</v>
         <v>Arguments = [term()]</v>
         <v>Time = integer() in microseconds</v>
         <v>Value = term()</v>
       </type>
       <desc>
-        <p>Evaluates <c>apply(Module, Function, Arguments)</c> and measures
-          the elapsed real time. 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>
+        <p></p>
+        <taglist>
+          <tag><c>tc/3</c></tag>
+          <item>
+            <p>Evaluates <c>apply(Module, Function, Arguments)</c> and measures
+              the elapsed real time. 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>
+          </item>
+          <tag><c>tc/2</c></tag>
+          <item>
+            <p>Evaluates <c>apply(Fun, Arguments)</c>. Otherwise works
+            like <c>tc/3</c>.</p>
+          </item>
+        </taglist>
       </desc>
     </func>
     <func>
diff --git a/lib/stdlib/src/timer.erl b/lib/stdlib/src/timer.erl
index 36fdb48c75..12bbd45703 100644
--- a/lib/stdlib/src/timer.erl
+++ b/lib/stdlib/src/timer.erl
@@ -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/3, now_diff/2,
+	 cancel/1, sleep/1, tc/2, tc/3, now_diff/2,
 	 seconds/1, minutes/1, hours/1, hms/3]).
 
 -export([start_link/0, start/0, 
@@ -98,6 +98,17 @@ sleep(T) ->
     after T -> ok
     end.
 
+
+%%
+%% 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(),
+    {now_diff(After, Before), Val}.
+
 %%
 %% Measure the execution time (in microseconds) for an MFA.
 %%
diff --git a/lib/stdlib/test/timer_simple_SUITE.erl b/lib/stdlib/test/timer_simple_SUITE.erl
index 021a22c61b..6aa2b7b945 100644
--- a/lib/stdlib/test/timer_simple_SUITE.erl
+++ b/lib/stdlib/test/timer_simple_SUITE.erl
@@ -224,11 +224,19 @@ 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 
-    ?line {Res, ok} = timer:tc(timer, sleep, [500]),  
-    ?line ok = 	if 
-		    Res < 500*1000 -> {too_early, Res};  % Too early
-		    Res > 800*1000 -> {too_late, Res};  % Too much time
+    % This should both sleep and tc/3
+    ?line {Res1, ok} = timer:tc(timer, sleep, [500]),
+    ?line ok = 	if
+		    Res1 < 500*1000 -> {too_early, Res1}; % Too early
+		    Res1 > 800*1000 -> {too_late, Res1};  % Too much time
+		    true -> ok
+		end,
+
+    % This should both sleep and 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,