From 008b44b75a5abf32b26365334597835a3c6fcfd1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Mon, 9 Oct 2017 12:35:15 +0200
Subject: Implement dumping of maps in crash dumps

Maps would be dumped as the atom 'undefined', which is
not very informative.
---
 lib/observer/src/crashdump_viewer.erl | 41 +++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

(limited to 'lib/observer/src')

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);
-- 
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