1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (the "License"); you may not use this file except in
%% compliance with the License. You may obtain a copy of the License at
%% http://www.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
%% License for the specific language governing rights and limitations
%% under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developers of the Original Code are Rabbit Technologies Ltd.
%%
%% Copyright (C) 2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(rabbit_upgrade).
-export([maybe_upgrade/0, read_version/0, write_version/0, desired_version/0]).
-include("rabbit.hrl").
-define(VERSION_FILENAME, "schema_version").
-define(LOCK_FILENAME, "schema_upgrade_lock").
%% -------------------------------------------------------------------
-ifdef(use_specs).
-spec(maybe_upgrade/0 :: () -> 'ok' | 'version_not_available').
-spec(read_version/0 ::
() -> {'ok', [any()]} | rabbit_types:error(any())).
-spec(write_version/0 :: () -> 'ok').
-spec(desired_version/0 :: () -> [atom()]).
-endif.
%% -------------------------------------------------------------------
%% Try to upgrade the schema. If no information on the existing schema
%% could be found, do nothing. rabbit_mnesia:check_schema_integrity()
%% will catch the problem.
maybe_upgrade() ->
case read_version() of
{ok, CurrentHeads} ->
G = load_graph(),
case unknown_heads(CurrentHeads, G) of
[] ->
case upgrades_to_apply(CurrentHeads, G) of
[] -> ok;
Upgrades -> apply_upgrades(Upgrades)
end;
Unknown ->
exit({future_upgrades_found, Unknown})
end,
true = digraph:delete(G),
ok;
{error, enoent} ->
version_not_available
end.
read_version() ->
case rabbit_misc:read_term_file(schema_filename()) of
{ok, [Heads]} -> {ok, Heads};
{error, E} -> {error, E}
end.
write_version() ->
ok = rabbit_misc:write_term_file(schema_filename(), [desired_version()]),
ok.
desired_version() ->
G = load_graph(),
Version = heads(G),
true = digraph:delete(G),
Version.
%% -------------------------------------------------------------------
load_graph() ->
Upgrades = rabbit_misc:all_module_attributes(rabbit_upgrade),
rabbit_misc:build_acyclic_graph(
fun vertices/2, fun edges/2, fun graph_build_error/1, Upgrades).
vertices(Module, Steps) ->
[{StepName, {Module, StepName}} || {StepName, _Reqs} <- Steps].
edges(_Module, Steps) ->
[{Require, StepName} || {StepName, Requires} <- Steps, Require <- Requires].
graph_build_error({vertex, duplicate, StepName}) ->
exit({duplicate_upgrade, StepName});
graph_build_error({edge, E, From, To}) ->
exit({E, From, To}).
unknown_heads(Heads, G) ->
[H || H <- Heads, digraph:vertex(G, H) =:= false].
upgrades_to_apply(Heads, G) ->
%% Take all the vertices which can reach the known heads. That's
%% everything we've already applied. Subtract that from all
%% vertices: that's what we have to apply.
Unsorted = sets:to_list(
sets:subtract(
sets:from_list(digraph:vertices(G)),
sets:from_list(digraph_utils:reaching(Heads, G)))),
%% Form a subgraph from that list and find a topological ordering
%% so we can invoke them in order.
[element(2, digraph:vertex(G, StepName))
|| StepName <- digraph_utils:topsort(digraph_utils:subgraph(G, Unsorted))].
heads(G) ->
lists:sort([V || V <- digraph:vertices(G), digraph:out_degree(G, V) =:= 0]).
%% -------------------------------------------------------------------
apply_upgrades(Upgrades) ->
LockFile = lock_filename(),
case file:open(LockFile, [write, exclusive]) of
{ok, Lock} ->
ok = file:close(Lock),
info("Upgrades: ~w to apply~n", [length(Upgrades)]),
[apply_upgrade(Upgrade) || Upgrade <- Upgrades],
info("Upgrades: All applied~n", []),
ok = write_version(),
ok = file:delete(LockFile);
{error, eexist} ->
exit(previous_upgrade_failed);
{error, _} = Error ->
exit(Error)
end.
apply_upgrade({M, F}) ->
info("Upgrades: Applying ~w:~w~n", [M, F]),
ok = apply(M, F, []).
%% -------------------------------------------------------------------
schema_filename() ->
filename:join(dir(), ?VERSION_FILENAME).
lock_filename() ->
filename:join(dir(), ?LOCK_FILENAME).
%% NB: we cannot use rabbit_log here since it may not have been
%% started yet
info(Msg, Args) ->
error_logger:info_msg(Msg, Args).
dir() ->
rabbit_mnesia:dir().
|
