From 7eec056d380377571a621030ab41f548ddf1a6e0 Mon Sep 17 00:00:00 2001
From: Ulf Wiger <ulf.wiger@klarna.com>
Date: Wed, 4 Nov 2015 16:58:50 +0100
Subject: mnesia_ext: Add create_external and increase protocol version to
 monitor

new protocol version to handle new schema fields
---
 lib/mnesia/src/mnesia_schema.erl | 55 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 7 deletions(-)

(limited to 'lib/mnesia/src/mnesia_schema.erl')

diff --git a/lib/mnesia/src/mnesia_schema.erl b/lib/mnesia/src/mnesia_schema.erl
index 782493fb4f..76a9dbf26c 100644
--- a/lib/mnesia/src/mnesia_schema.erl
+++ b/lib/mnesia/src/mnesia_schema.erl
@@ -647,7 +647,15 @@ cs2list(Cs) when is_record(Cs, cstruct) ->
 cs2list(CreateList) when is_list(CreateList) ->
     CreateList;
 
-%% since 4.6
+cs2list(Cs) when element(1, Cs) == cstruct, tuple_size(Cs) == 20 ->
+    Tags = [name,type,
+	    ram_copies,disc_copies,disc_only_copies,external_copies,
+	    load_order,access_mode,majority,index,snmp,local_content,
+	    record_name,attributes,
+	    user_properties,frag_properties,storage_properties,
+	    cookie,version],
+    rec2list(Tags, Tags, 2, Cs);
+%% since vsn-4.6 (protocol 8.2 or older)
 cs2list(Cs) when element(1, Cs) == cstruct, tuple_size(Cs) == 19 ->
     Tags = [name,type,ram_copies,disc_copies,disc_only_copies,
 	    load_order,access_mode,majority,index,snmp,local_content,
@@ -657,7 +665,17 @@ cs2list(Cs) when element(1, Cs) == cstruct, tuple_size(Cs) == 19 ->
     rec2list(Tags, Tags, 2, Cs).
 
 cs2list(false, Cs) ->
-    cs2list(Cs).
+    cs2list(Cs);
+cs2list({8,3}, Cs) ->
+    cs2list(Cs);
+cs2list({8,Minor}, Cs) when Minor =:= 2; Minor =:= 1 ->
+    Orig = record_info(fields, cstruct),
+    Tags = [name,type,ram_copies,disc_copies,disc_only_copies,
+	    load_order,access_mode,majority,index,snmp,local_content,
+	    record_name,attributes,
+	    user_properties,frag_properties,storage_properties,
+	    cookie,version],
+    rec2list(Tags, Orig, 2, Cs).
 
 rec2list([Tag | Tags], [Tag | Orig], Pos, Rec) ->
     Val = element(Pos, Rec),
@@ -667,8 +685,19 @@ rec2list([], _, _Pos, _Rec) ->
 rec2list(Tags, [_|Orig], Pos, Rec) ->
     rec2list(Tags, Orig, Pos+1, Rec).
 
-normalize_cs(Cstructs, _Node) ->
-    Cstructs.
+normalize_cs(Cstructs, Node) ->
+    %% backward-compatibility hack; normalize before returning
+    case need_old_cstructs([Node]) of
+	false ->
+	    Cstructs;
+	Version ->
+	    %% some other format
+	    [convert_cs(Version, Cs) || Cs <- Cstructs]
+    end.
+
+convert_cs(Version, Cs) ->
+    Fields = [Value || {_, Value} <- cs2list(Version, Cs)],
+    list_to_tuple([cstruct|Fields]).
 
 list2cs(List) when is_list(List) ->
     Name = pick(unknown, name, List, must),
@@ -2795,11 +2824,23 @@ do_merge_schema(LockTabs0) ->
     end.
 
 fetch_cstructs(Node) ->
-    rpc:call(Node, mnesia_controller, get_remote_cstructs, []).
+    Convert = mnesia_monitor:needs_protocol_conversion(Node),
+    case rpc:call(Node, mnesia_controller, get_remote_cstructs, [])  of
+	{cstructs, Cs0, RemoteRunning1} when Convert ->
+	    {cstructs, [list2cs(cs2list(Cs)) || Cs <- Cs0], RemoteRunning1};
+	Result ->
+	    Result
+    end.
 
-need_old_cstructs() -> false.
+need_old_cstructs() ->
+    need_old_cstructs(val({schema, where_to_write})).
 
-need_old_cstructs(_Nodes) -> false.
+need_old_cstructs(Nodes) ->
+    Filter = fun(Node) -> mnesia_monitor:needs_protocol_conversion(Node) end,
+    case lists:filter(Filter, Nodes) of
+	[] -> false;
+	Ns -> lists:min([element(1, ?catch_val({protocol, Node})) || Node <- Ns])
+    end.
 
 tab_to_nodes(Tab) when is_atom(Tab) ->
     Cs = val({Tab, cstruct}),
-- 
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