Merge branch 'hans/ssh/circ_buffer/OTP-15020' into maint

* hans/ssh/circ_buffer/OTP-15020:
  ssh: Test group for circular buffer tracing
  ssh: Circular trace buffer primitives
  ssh: Make dbg test one group in ssh_dbg_SUITE

3 files changed, 194 insertions, 7 deletions

diff --git a/lib/ssh/src/ssh.hrl b/lib/ssh/src/ssh.hrl
index 9631427749..01c44cb371 100644
--- a/lib/ssh/src/ssh.hrl
+++ b/lib/ssh/src/ssh.hrl
@@ -492,4 +492,29 @@
 -define(wr_record(N), ?wr_record(N, [])).
 
 
+%% Circular trace buffer macros
+
+-record(circ_buf_entry,
+        {
+          module,
+          line,
+          function,
+          pid = self(),
+          value
+        }).
+
+-define(CIRC_BUF_IN(VALUE),
+        ssh_dbg:cbuf_in(
+          #circ_buf_entry{module = ?MODULE,
+                          line = ?LINE,
+                          function = {?FUNCTION_NAME,?FUNCTION_ARITY},
+                          pid = self(),
+                          value = (VALUE)
+                         })
+       ).
+
+-define(CIRC_BUF_IN_ONCE(VALUE),
+        ((fun(V) -> ?CIRC_BUF_IN(V), V end)(VALUE))
+       ).
+                 
 -endif. % SSH_HRL defined
diff --git a/lib/ssh/src/ssh_dbg.erl b/lib/ssh/src/ssh_dbg.erl
index b53c09b17d..3681e03cc2 100644
--- a/lib/ssh/src/ssh_dbg.erl
+++ b/lib/ssh/src/ssh_dbg.erl
@@ -54,7 +54,13 @@
          start_tracer/0, start_tracer/1,
          on/1,  on/0,
          off/1, off/0,
-         go_on/0
+         go_on/0,
+         %% Circular buffer
+         cbuf_start/0, cbuf_start/1,
+         cbuf_stop_clear/0,
+         cbuf_in/1,
+         cbuf_list/0,
+         fmt_cbuf_items/0, fmt_cbuf_item/1
 	]).
 
 -export([shrink_bin/1,
@@ -331,3 +337,103 @@ ts({_,_,Usec}=Now) when is_integer(Usec) ->
     io_lib:format("~.2.0w:~.2.0w:~.2.0w.~.6.0w",[HH,MM,SS,Usec]);
 ts(_) ->
     "-".
+
+%%%================================================================
+-define(CIRC_BUF, circ_buf).
+
+cbuf_start() ->
+    cbuf_start(20).
+
+cbuf_start(CbufMaxLen) ->
+    put(?CIRC_BUF, {CbufMaxLen,queue:new()}),
+    ok.
+
+
+cbuf_stop_clear() ->
+    case erase(?CIRC_BUF) of
+        undefined ->
+            [];
+        {_CbufMaxLen,Queue} ->
+            queue:to_list(Queue)
+    end.
+
+
+cbuf_in(Value) ->
+    case get(?CIRC_BUF) of
+        undefined ->
+            disabled;
+        {CbufMaxLen,Queue} ->
+            UpdatedQueue =
+                try queue:head(Queue) of
+                    {Value, TS0, Cnt0} ->
+                        %% Same Value as last saved in the queue
+                        queue:in_r({Value, TS0, Cnt0+1},
+                                 queue:drop(Queue)
+                                );
+                    _ ->
+                        queue:in_r({Value, erlang:timestamp(), 1},
+                                   truncate_cbuf(Queue, CbufMaxLen)
+                                )
+                catch
+                    error:empty ->
+                        queue:in_r({Value, erlang:timestamp(), 1}, Queue)
+                end,
+            put(?CIRC_BUF, {CbufMaxLen,UpdatedQueue}),
+            ok
+    end.
+
+
+cbuf_list() ->
+    case get(?CIRC_BUF) of
+        undefined ->
+            [];
+        {_CbufMaxLen,Queue} ->
+            queue:to_list(Queue)
+    end.
+
+
+truncate_cbuf(Q, CbufMaxLen) ->
+    case queue:len(Q) of
+        N when N>=CbufMaxLen ->
+            truncate_cbuf(element(2,queue:out_r(Q)), CbufMaxLen);
+        _ ->
+            Q
+    end.
+
+fmt_cbuf_items() ->
+    lists:flatten(
+      io_lib:format("Circular trace buffer. Latest item first.~n~s~n",
+                    [case get(?CIRC_BUF) of
+                         {Max,_} ->
+                             L = cbuf_list(),
+                             [io_lib:format("==== ~.*w: ~s~n",[num_digits(Max),N,fmt_cbuf_item(X)]) ||
+                                 {N,X} <- lists:zip(lists:seq(1,length(L)), L)
+                             ];
+                         _ ->
+                             io_lib:format("Not started.~n",[])
+                     end])).
+                   
+
+num_digits(0) -> 1;
+num_digits(N) when N>0 -> 1+trunc(math:log10(N)).
+    
+
+fmt_cbuf_item({Value, TimeStamp, N}) ->
+    io_lib:format("~s~s~n~s~n",
+                  [fmt_ts(TimeStamp),
+                   [io_lib:format(" (Repeated ~p times)",[N]) || N>1],
+                   fmt_value(Value)]).
+
+
+fmt_ts(TS = {_,_,Us}) ->
+    {{YY,MM,DD},{H,M,S}} = calendar:now_to_universal_time(TS),
+    io_lib:format("~w-~.2.0w-~.2.0w ~.2.0w:~.2.0w:~.2.0w.~.6.0w UTC",[YY,MM,DD,H,M,S,Us]).
+    
+fmt_value(#circ_buf_entry{module = M,
+                          line = L,
+                          function = {F,A},
+                          pid = Pid,
+                          value = V}) ->
+    io_lib:format("~p:~p  ~p/~p ~p~n~s",[M,L,F,A,Pid,fmt_value(V)]);
+fmt_value(Value) ->
+    io_lib:format("~p",[Value]).
diff --git a/lib/ssh/test/ssh_dbg_SUITE.erl b/lib/ssh/test/ssh_dbg_SUITE.erl
index 5439817d10..ab7918fa90 100644
--- a/lib/ssh/test/ssh_dbg_SUITE.erl
+++ b/lib/ssh/test/ssh_dbg_SUITE.erl
@@ -38,11 +38,20 @@ suite() ->
      {timetrap,{seconds,60}}].
 
 all() -> 
-    [basic,
-     dbg_alg_terminate,
-     dbg_ssh_messages,
-     dbg_connections,
-     dbg_channels
+    [{group, dbg},
+     {group, circ_buf}
+    ].
+
+groups() ->
+    [{dbg, [], [dbg_basic,
+                dbg_alg_terminate,
+                dbg_ssh_messages,
+                dbg_connections,
+                dbg_channels]},
+     {circ_buf, [], [cb_basic,
+                     cb_print,
+                     cb_macros_print
+                    ]}
     ].
 
 %%--------------------------------------------------------------------
@@ -82,7 +91,7 @@ end_per_testcase(_TC, Config) ->
 %% Test Cases --------------------------------------------------------
 %%--------------------------------------------------------------------
 
-basic(_Config) ->
+dbg_basic(_Config) ->
     L0 = ssh_dbg:start(),
     true = is_pid(whereis(ssh_dbg)),
     true = is_list(L0),
@@ -342,6 +351,53 @@ dbg_channels(Config) ->
     stop_and_fail_if_unhandled_dbg_msgs(Ref, [C,D], Pid).
 
 %%--------------------------------------------------------------------
+cb_basic(_Config) ->
+    %% Check that the circular buffer is disabled at start:
+    [] = ssh_dbg:cbuf_list(),
+    disabled = ssh_dbg:cbuf_in(anything),
+    [] = ssh_dbg:cbuf_list(),
+    %% Start it and enter three values, first is duplicated;
+    ok = ssh_dbg:cbuf_start(3),
+    ok = ssh_dbg:cbuf_in(v1),
+    ok = ssh_dbg:cbuf_in(v1),
+    ok = ssh_dbg:cbuf_in(v2),
+    ok = ssh_dbg:cbuf_in(v3),
+    [{v3,_,1}, {v2,_,1}, {v1,_,2}] = ssh_dbg:cbuf_list(),
+    %% Check that a fourth value erase the first entered:
+    ok = ssh_dbg:cbuf_in(v4),
+    [{v4,_,1}, {v3,_,1}, {v2,_,1}] = ssh_dbg:cbuf_list(),
+    %% Check that entering a value that is in the tail but not in the head is treated as a new value:
+    ok = ssh_dbg:cbuf_in(v2),
+    [{v2,_,1}, {v4,_,1}, {v3,_,1}] = ssh_dbg:cbuf_list(),
+    %% Stop and check that the buffer is returned:
+    [{v2,_,1}, {v4,_,1}, {v3,_,1}] = ssh_dbg:cbuf_stop_clear(),
+    %% Stopping a stopped buffer returns empty:
+    [] = ssh_dbg:cbuf_stop_clear(),
+    %% Check that a value can't be entered in a stopped buffer:
+    disabled = ssh_dbg:cbuf_in(v2).
+
+%%--------------------------------------------------------------------
+cb_print(_Config) ->
+    ssh_dbg:cbuf_start(),
+    [begin
+         ssh_dbg:cbuf_in(V),
+         ct:log("Enter ~p",[V])
+     end || V <- lists:seq(1,10)],
+    ct:log("~s",[ssh_dbg:fmt_cbuf_items()]),
+    ssh_dbg:cbuf_stop_clear().
+
+%%--------------------------------------------------------------------
+cb_macros_print(_Config) ->
+    ssh_dbg:cbuf_start(),
+    [begin
+         V = {test,V0},
+         ?CIRC_BUF_IN(V),
+         ct:log("Enter ~p",[V])
+     end || V0 <- lists:seq(1,5)],
+    ct:log("~s",[ssh_dbg:fmt_cbuf_items()]),
+    ssh_dbg:cbuf_stop_clear().
+
+%%--------------------------------------------------------------------
 %%--------------------------------------------------------------------
 %%--------------------------------------------------------------------