From 8ea01dd6bd7e0f47ec72ec63bd79d20068f467e8 Mon Sep 17 00:00:00 2001
From: ILYA Khlopotov <iilyak@apache.org>
Date: Thu, 13 Oct 2016 10:27:25 -0700
Subject: [PATCH] Truncate revs returned from couch_db:open_doc_revs

Return max revs_limit revisions from couch_db:open_doc_revs.

COUCHDB-3193
---
 src/couch_db.erl            |  4 +-
 test/couch_db_doc_tests.erl | 94 +++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 2 deletions(-)
 create mode 100644 test/couch_db_doc_tests.erl

diff --git a/src/couch_db.erl b/src/couch_db.erl
index 26c6ae72..3955d8b8 100644
--- a/src/couch_db.erl
+++ b/src/couch_db.erl
@@ -1412,7 +1412,7 @@ make_doc(_Db, Id, Deleted, nil = _Bp, RevisionPath) ->
         atts = [],
         deleted = Deleted
     };
-make_doc(#db{fd=Fd}=Db, Id, Deleted, Bp, RevisionPath) ->
+make_doc(#db{fd=Fd, revs_limit=RevsLimit}=Db, Id, Deleted, Bp, {Pos, Revs}) ->
     {BodyData, Atts0} = case Bp of
         nil ->
             {[], []};
@@ -1428,7 +1428,7 @@ make_doc(#db{fd=Fd}=Db, Id, Deleted, Bp, RevisionPath) ->
     Atts = [couch_att:from_disk_term(Fd, T) || T <- Atts0],
     Doc = #doc{
         id = Id,
-        revs = RevisionPath,
+        revs = {Pos, lists:sublist(Revs, 1, RevsLimit)},
         body = BodyData,
         atts = Atts,
         deleted = Deleted
diff --git a/test/couch_db_doc_tests.erl b/test/couch_db_doc_tests.erl
new file mode 100644
index 00000000..aa9c6fd7
--- /dev/null
+++ b/test/couch_db_doc_tests.erl
@@ -0,0 +1,94 @@
+% Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_db_doc_tests).
+
+-include_lib("couch/include/couch_eunit.hrl").
+-include_lib("couch/include/couch_db.hrl").
+
+start() ->
+    test_util:start_couch([ioq]).
+
+
+setup() ->
+    DbName = ?tempdb(),
+    config:set("couchdb", "stem_interactive_updates", "false", false),
+    {ok, Db} = couch_db:create(DbName, [?ADMIN_CTX]),
+    couch_db:close(Db),
+    DbName.
+
+
+teardown(DbName) ->
+    ok = couch_server:delete(DbName, [?ADMIN_CTX]),
+    ok.
+
+
+couch_db_doc_test_() ->
+    {
+        "CouchDB doc tests",
+        {
+            setup,
+            fun start/0, fun test_util:stop_couch/1,
+            {
+                foreach,
+                fun setup/0, fun teardown/1,
+                [
+                    fun should_truncate_number_of_revisions/1
+                ]
+            }
+        }
+    }.
+
+
+should_truncate_number_of_revisions(DbName) ->
+    DocId = <<"foo">>,
+    Db = open_db(DbName),
+    couch_db:set_revs_limit(Db, 5),
+    Rev = create_doc(Db, DocId),
+    Rev10 = add_revisions(Db, DocId, Rev, 10),
+    {ok, [{ok, #doc{revs = {11, Revs}}}]} = open_doc_rev(Db, DocId, Rev10),
+    ?_assertEqual(5, length(Revs)).
+
+
+open_db(DbName) ->
+    {ok, Db} = couch_db:open_int(DbName, [?ADMIN_CTX]),
+    Db.
+
+
+create_doc(Db, DocId) ->
+    add_revision(Db, DocId, undefined).
+
+
+open_doc_rev(Db0, DocId, Rev) ->
+    {ok, Db} = couch_db:reopen(Db0),
+    couch_db:open_doc_revs(Db, DocId, [couch_doc:parse_rev(Rev)], []).
+
+
+add_revision(Db, DocId, undefined) ->
+    add_revision(Db, DocId, []);
+add_revision(Db, DocId, Rev) when is_binary(Rev) ->
+    add_revision(Db, DocId, [{<<"_rev">>, Rev}]);
+add_revision(Db0, DocId, Rev) ->
+    {ok, Db} = couch_db:reopen(Db0),
+    Doc = couch_doc:from_json_obj({[
+        {<<"_id">>, DocId},
+        {<<"value">>, DocId}
+    ] ++ Rev}),
+    {ok, NewRev} = couch_db:update_doc(Db, Doc, []),
+    {ok, _} = couch_db:ensure_full_commit(Db),
+    couch_doc:rev_to_str(NewRev).
+
+
+add_revisions(Db, DocId, Rev, N) ->
+    lists:foldl(fun(_, OldRev) ->
+        add_revision(Db, DocId, OldRev)
+    end, Rev, lists:seq(1, N)).