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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_task_status).
-behaviour(gen_server).
% This module allows is used to track the status of long running tasks.
% Long running tasks register (add_task/3) then update their status (update/1)
% and the task and status is added to tasks list. When the tracked task dies
% it will be automatically removed the tracking. To get the tasks list, use the
% all/0 function
-export([start_link/0, stop/0]).
-export([all/0, add_task/3, update/1, update/2, set_update_frequency/1]).
-export([init/1, terminate/2, code_change/3]).
-export([handle_call/3, handle_cast/2, handle_info/2]).
-import(couch_util, [to_binary/1]).
-include("couch_db.hrl").
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
stop() ->
gen_server:cast(?MODULE, stop).
all() ->
gen_server:call(?MODULE, all).
add_task(Type, TaskName, StatusText) ->
put(task_status_update, {{0, 0, 0}, 0}),
Msg = {
add_task,
to_binary(Type),
to_binary(TaskName),
to_binary(StatusText)
},
gen_server:call(?MODULE, Msg).
set_update_frequency(Msecs) ->
put(task_status_update, {{0, 0, 0}, Msecs * 1000}).
update(StatusText) ->
update("~s", [StatusText]).
update(Format, Data) ->
{LastUpdateTime, Frequency} = get(task_status_update),
case timer:now_diff(Now = now(), LastUpdateTime) >= Frequency of
true ->
put(task_status_update, {Now, Frequency}),
Msg = ?l2b(io_lib:format(Format, Data)),
gen_server:cast(?MODULE, {update_status, self(), Msg});
false ->
ok
end.
init([]) ->
% read configuration settings and register for configuration changes
ets:new(?MODULE, [ordered_set, protected, named_table]),
{ok, nil}.
terminate(_Reason,_State) ->
ok.
handle_call({add_task, Type, TaskName, StatusText}, {From, _}, Server) ->
case ets:lookup(?MODULE, From) of
[] ->
true = ets:insert(?MODULE, {From, {Type, TaskName, StatusText}}),
erlang:monitor(process, From),
{reply, ok, Server};
[_] ->
{reply, {add_task_error, already_registered}, Server}
end;
handle_call(all, _, Server) ->
All = [
[
{type, Type},
{task, Task},
{status, Status},
{pid, ?l2b(pid_to_list(Pid))}
]
||
{Pid, {Type, Task, Status}} <- ets:tab2list(?MODULE)
],
{reply, All, Server}.
handle_cast({update_status, Pid, StatusText}, Server) ->
[{Pid, {Type, TaskName, _StatusText}}] = ets:lookup(?MODULE, Pid),
true = ets:insert(?MODULE, {Pid, {Type, TaskName, StatusText}}),
{noreply, Server};
handle_cast(stop, State) ->
{stop, normal, State}.
handle_info({'DOWN', _MonitorRef, _Type, Pid, _Info}, Server) ->
%% should we also erlang:demonitor(_MonitorRef), ?
ets:delete(?MODULE, Pid),
{noreply, Server}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
|
