Implement dumping of maps in crash dumps

Maps would be dumped as the atom 'undefined', which is
not very informative.

4 files changed, 165 insertions, 10 deletions

diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index b826e6c5d3..9ae1a36d6f 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -32,6 +32,7 @@
 #include "dist.h"
 #include "beam_catches.h"
 #include "erl_binary.h"
+#include "erl_map.h"
 #define ERTS_WANT_EXTERNAL_TAGS
 #include "external.h"
 
@@ -498,11 +499,77 @@ heap_dump(fmtfn_t to, void *to_arg, Eterm x)
 		    erts_print(to, to_arg, "p<%beu.%beu>\n",
 			       port_channel_no(x), port_number(x));
 		    *ptr = OUR_NIL;
+		} else if (is_map_header(hdr)) {
+                    if (is_flatmap_header(hdr)) {
+                        flatmap_t* fmp = (flatmap_t *) flatmap_val(x);
+                        Eterm* values = ptr + sizeof(flatmap_t) / sizeof(Eterm);
+                        Uint map_size = fmp->size;
+                        int i;
+
+                        erts_print(to, to_arg, "Mf" ETERM_FMT ":", map_size);
+                        dump_element(to, to_arg, fmp->keys);
+                        erts_putc(to, to_arg, ':');
+                        for (i = 0; i < map_size; i++) {
+                            dump_element(to, to_arg, values[i]);
+                            if (is_immed(values[i])) {
+                                values[i] = make_small(0);
+                            }
+                            if (i < map_size-1) {
+                                erts_putc(to, to_arg, ',');
+                            }
+                        }
+                        erts_putc(to, to_arg, '\n');
+                        *ptr = OUR_NIL;
+                        x = fmp->keys;
+                        if (map_size) {
+                            fmp->keys = (Eterm) next;
+                            next = &values[map_size-1];
+                        }
+                        continue;
+                    } else {
+                        Uint i;
+                        Uint sz = 0;
+                        Eterm* nodes = ptr + 1;
+
+                        switch (MAP_HEADER_TYPE(hdr)) {
+                        case MAP_HEADER_TAG_HAMT_HEAD_ARRAY:
+                            nodes++;
+                            sz = 16;
+                            erts_print(to, to_arg, "Mh" ETERM_FMT ":" ETERM_FMT ":",
+                                       hashmap_size(x), sz);
+                            break;
+                        case MAP_HEADER_TAG_HAMT_HEAD_BITMAP:
+                            nodes++;
+                            sz = hashmap_bitcount(MAP_HEADER_VAL(hdr));
+                            erts_print(to, to_arg, "Mh" ETERM_FMT ":" ETERM_FMT ":",
+                                       hashmap_size(x), sz);
+                            break;
+                        case MAP_HEADER_TAG_HAMT_NODE_BITMAP:
+                            sz = hashmap_bitcount(MAP_HEADER_VAL(hdr));
+                            erts_print(to, to_arg, "Mn" ETERM_FMT ":", sz);
+                            break;
+                        }
+                        *ptr = OUR_NIL;
+                        for (i = 0; i < sz; i++) {
+                            dump_element(to, to_arg, nodes[i]);
+                            if (is_immed(nodes[i])) {
+                                nodes[i] = make_small(0);
+                            }
+                            if (i < sz-1) {
+                                erts_putc(to, to_arg, ',');
+                            }
+                        }
+                        erts_putc(to, to_arg, '\n');
+                        x = nodes[0];
+                        nodes[0] = (Eterm) next;
+                        next = &nodes[sz-1];
+                        continue;
+                    }
 		} else {
 		    /*
 		     * All other we dump in the external term format.
 		     */
-			dump_externally(to, to_arg, x);
+                    dump_externally(to, to_arg, x);
 		    erts_putc(to, to_arg, '\n');
 		    *ptr = OUR_NIL;
 		}
@@ -564,11 +631,6 @@ dump_externally(fmtfn_t to, void *to_arg, Eterm term)
 	}
     }
 
-    /* Do not handle maps */
-    if (is_map(term)) {
-        term = am_undefined;
-    }
-
     s = p = sbuf;
     erts_encode_ext(term, &p);
     erts_print(to, to_arg, "E%X:", p-s);
diff --git a/lib/observer/src/crashdump_viewer.erl b/lib/observer/src/crashdump_viewer.erl
index 95e12887cd..bc3ce5d547 100644
--- a/lib/observer/src/crashdump_viewer.erl
+++ b/lib/observer/src/crashdump_viewer.erl
@@ -2589,8 +2589,26 @@ parse_heap_term("Ys"++Line0, Addr, BinAddrAdj, D0) ->	%Sub binary.
 		   end
 	   end,
     D = gb_trees:insert(Addr, Term, D0),
-    {Term,Line,D}.
-
+    {Term,Line,D};
+parse_heap_term("Mf"++Line0, Addr, BinAddrAdj, D0) -> %Flatmap.
+    {Size,":"++Line1} = get_hex(Line0),
+    {Keys,":"++Line2,D1} = parse_term(Line1, BinAddrAdj, D0),
+    {Values,Line,D2} = parse_tuple(Size, Line2, Addr,BinAddrAdj, D1, []),
+    Pairs = zip_tuples(tuple_size(Keys), Keys, Values, []),
+    Map = maps:from_list(Pairs),
+    D = gb_trees:update(Addr, Map, D2),
+    {Map,Line,D};
+parse_heap_term("Mh"++Line0, Addr, BinAddrAdj, D0) -> %Head node in a hashmap.
+    {MapSize,":"++Line1} = get_hex(Line0),
+    {N,":"++Line2} = get_hex(Line1),
+    {Nodes,Line,D1} = parse_tuple(N, Line2, Addr, BinAddrAdj, D0, []),
+    Map = maps:from_list(flatten_hashmap_nodes(Nodes)),
+    MapSize = maps:size(Map),                   %Assertion.
+    D = gb_trees:update(Addr, Map, D1),
+    {Map,Line,D};
+parse_heap_term("Mn"++Line0, Addr, BinAddrAdj, D) -> %Interior node in a hashmap.
+    {N,":"++Line} = get_hex(Line0),
+    parse_tuple(N, Line, Addr, BinAddrAdj, D, []).
 
 parse_tuple(0, Line, Addr, _, D0, Acc) ->
     Tuple = list_to_tuple(lists:reverse(Acc)),
@@ -2604,6 +2622,25 @@ parse_tuple(N, Line0, Addr, BinAddrAdj, D0, Acc) ->
 	    parse_tuple(N-1, Line, Addr, BinAddrAdj, D, [Term|Acc])
     end.
 
+zip_tuples(0, _T1, _T2, Acc) ->
+    Acc;
+zip_tuples(N, T1, T2, Acc) when N =< tuple_size(T1) ->
+    zip_tuples(N-1, T1, T2, [{element(N, T1),element(N, T2)}|Acc]).
+
+flatten_hashmap_nodes(Tuple) ->
+    flatten_hashmap_nodes_1(tuple_size(Tuple), Tuple, []).
+
+flatten_hashmap_nodes_1(0, _Tuple, Acc) ->
+    Acc;
+flatten_hashmap_nodes_1(N, Tuple0, Acc0) ->
+    case element(N, Tuple0) of
+        [K|V] ->
+            flatten_hashmap_nodes_1(N-1, Tuple0, [{K,V}|Acc0]);
+        Tuple when is_tuple(Tuple) ->
+            Acc = flatten_hashmap_nodes_1(N-1, Tuple0, Acc0),
+            flatten_hashmap_nodes_1(tuple_size(Tuple), Tuple, Acc)
+    end.
+
 parse_term([$H|Line0], BinAddrAdj, D) ->        %Pointer to heap term.
     {Ptr,Line} = get_hex(Line0),
     deref_ptr(Ptr, Line, BinAddrAdj, D);
diff --git a/lib/observer/test/crashdump_helper.erl b/lib/observer/test/crashdump_helper.erl
index f37d9057cb..04c8773498 100644
--- a/lib/observer/test/crashdump_helper.erl
+++ b/lib/observer/test/crashdump_helper.erl
@@ -19,7 +19,8 @@
 %%
 
 -module(crashdump_helper).
--export([n1_proc/2,remote_proc/2]).
+-export([n1_proc/2,remote_proc/2,
+         dump_maps/0,create_maps/0]).
 -compile(r18).
 -include_lib("common_test/include/ct.hrl").
 
@@ -92,3 +93,31 @@ remote_proc(P1,Creator) ->
 		  Creator ! {self(),done},
 		  receive after infinity -> ok end
 	  end).
+
+
+%%%
+%%% Test dumping of maps. Dumping of maps only from OTP 20.2.
+%%%
+
+dump_maps() ->
+    Parent = self(),
+    F = fun() ->
+                register(aaaaaaaa_maps, self()),
+                put(maps, create_maps()),
+                Parent ! {self(),done},
+                receive _ -> ok end
+        end,
+    Pid = spawn_link(F),
+    receive
+        {Pid,done} ->
+            {ok,Pid}
+    end.
+
+create_maps() ->
+    Map0 = maps:from_list([{I,[I,I+1]} || I <- lists:seq(1, 40)]),
+    Map1 = maps:from_list([{I,{a,[I,I*I],{}}} || I <- lists:seq(1, 100)]),
+    Map2 = maps:from_list([{{I},(I*I) bsl 24} || I <- lists:seq(1, 10000)]),
+    Map3 = lists:foldl(fun(I, A) ->
+                               A#{I=>I*I}
+                       end, Map2, lists:seq(-10, 0)),
+    #{a=>Map0,b=>Map1,c=>Map2,d=>Map3,e=>#{}}.
diff --git a/lib/observer/test/crashdump_viewer_SUITE.erl b/lib/observer/test/crashdump_viewer_SUITE.erl
index f9ac884743..0ec6d8dcfc 100644
--- a/lib/observer/test/crashdump_viewer_SUITE.erl
+++ b/lib/observer/test/crashdump_viewer_SUITE.erl
@@ -513,6 +513,22 @@ special(File,Procs) ->
             io:format("  unicode table name ok",[]),
 
             ok;
+        ".maps" ->
+	    %% I registered a process as aaaaaaaa_maps in the map dump
+	    %% to make sure it will be the first in the list when sorted
+	    %% on names.
+	    [#proc{pid=Pid0,name=Name}|_Rest] = lists:keysort(#proc.name,Procs),
+            "aaaaaaaa_maps" = Name,
+	    Pid = pid_to_list(Pid0),
+	    {ok,ProcDetails=#proc{},[]} = crashdump_viewer:proc_details(Pid),
+	    io:format("  process details ok",[]),
+
+	    #proc{dict=Dict} = ProcDetails,
+            io:format("~p\n", [Dict]),
+            Maps = crashdump_helper:create_maps(),
+            Maps = proplists:get_value(maps,Dict),
+            io:format("  maps ok",[]),
+            ok;
 	_ ->
 	    ok
     end,
@@ -582,8 +598,9 @@ do_create_dumps(DataDir,Rel) ->
                                  "-env ERL_CRASH_DUMP_BYTES " ++
                                      integer_to_list(Bytes)),
             CD6 = dump_with_unicode_atoms(DataDir,Rel,"unicode"),
+            CD7 = dump_with_maps(DataDir,Rel,"maps"),
             TruncatedDumps = truncate_dump(CD1),
-	    {[CD1,CD2,CD3,CD4,CD5,CD6|TruncatedDumps], DosDump};
+	    {[CD1,CD2,CD3,CD4,CD5,CD6,CD7|TruncatedDumps], DosDump};
 	_ ->
 	    {[CD1,CD2], DosDump}
     end.
@@ -699,6 +716,16 @@ dump_with_unicode_atoms(DataDir,Rel,DumpName) ->
     ?t:stop_node(n1),
     CD.
 
+dump_with_maps(DataDir,Rel,DumpName) ->
+    Opt = rel_opt(Rel),
+    Pz = "-pz \"" ++ filename:dirname(code:which(?MODULE)) ++ "\"",
+    PzOpt = [{args,Pz}],
+    {ok,N1} = ?t:start_node(n1,peer,Opt ++ PzOpt),
+    {ok,_Pid} = rpc:call(N1,crashdump_helper,dump_maps,[]),
+    CD = dump(N1,DataDir,Rel,DumpName),
+    ?t:stop_node(n1),
+    CD.
+
 dump(Node,DataDir,Rel,DumpName) ->
     Crashdump = filename:join(DataDir, dump_prefix(Rel)++DumpName),
     rpc:call(Node,os,putenv,["ERL_CRASH_DUMP",Crashdump]),