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% 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_view_compactor).
-include ("couch_db.hrl").
-export([start_compact/2]).
%% @spec start_compact(DbName::binary(), GroupId:binary()) -> ok
%% @doc Compacts the views. GroupId must not include the _design/ prefix
start_compact(DbName, GroupId) ->
Pid = couch_view:get_group_server(DbName, <<"_design/",GroupId/binary>>),
gen_server:cast(Pid, {start_compact, fun compact_group/2}).
%%=============================================================================
%% internal functions
%%=============================================================================
%% @spec compact_group(Group, NewGroup) -> ok
compact_group(Group, EmptyGroup) ->
#group{
current_seq = Seq,
id_btree = IdBtree,
name = GroupId,
views = Views
} = Group,
#group{
dbname = DbName,
fd = Fd,
id_btree = EmptyIdBtree,
sig = Sig,
views = EmptyViews
} = EmptyGroup,
erlang:monitor(process, Fd),
{ok, Db} = couch_db:open(DbName, []),
{ok, {Count, _}} = couch_btree:full_reduce(Db#db.id_tree),
<<"_design", ShortName/binary>> = GroupId,
TaskName = <<DbName/binary, ShortName/binary>>,
couch_task_status:add_task(<<"View Group Compaction">>, TaskName, <<"">>),
Fun = fun(KV, {Bt, Acc, TotalCopied}) ->
if TotalCopied rem 10000 =:= 0 ->
couch_task_status:update("Copied ~p of ~p Ids (~p%)",
[TotalCopied, Count, (TotalCopied*100) div Count]),
{ok, Bt2} = couch_btree:add(Bt, lists:reverse([KV|Acc])),
{ok, {Bt2, [], TotalCopied+1}};
true ->
{ok, {Bt, [KV|Acc], TotalCopied+1}}
end
end,
{ok, _, {Bt3, Uncopied, _Total}} = couch_btree:foldl(IdBtree, Fun,
{EmptyIdBtree, [], 0}),
{ok, NewIdBtree} = couch_btree:add(Bt3, lists:reverse(Uncopied)),
NewViews = lists:map(fun({View, EmptyView}) ->
compact_view(View, EmptyView)
end, lists:zip(Views, EmptyViews)),
NewGroup = EmptyGroup#group{
id_btree=NewIdBtree,
views=NewViews,
current_seq=Seq
},
Pid = ets:lookup_element(group_servers_by_sig, {DbName, Sig}, 2),
gen_server:cast(Pid, {compact_done, NewGroup}).
%% @spec compact_view(View, EmptyView) -> CompactView
compact_view(View, EmptyView) ->
{ok, Count} = couch_view:get_row_count(View),
%% Key is {Key,DocId}
Fun = fun(KV, {Bt, Acc, TotalCopied}) ->
if TotalCopied rem 10000 =:= 0 ->
couch_task_status:update("View #~p: copied ~p of ~p KVs (~p%)",
[View#view.id_num, TotalCopied, Count, (TotalCopied*100) div Count]),
{ok, Bt2} = couch_btree:add(Bt, lists:reverse([KV|Acc])),
{ok, {Bt2, [], TotalCopied + 1}};
true ->
{ok, {Bt, [KV|Acc], TotalCopied + 1}}
end
end,
{ok, _, {Bt3, Uncopied, _Total}} = couch_btree:foldl(View#view.btree, Fun,
{EmptyView#view.btree, [], 0}),
{ok, NewBt} = couch_btree:add(Bt3, lists:reverse(Uncopied)),
EmptyView#view{btree = NewBt}.
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