| % 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). |
| -vsn(1). |
| |
| % This module is used to track the status of long running tasks. |
| % Long running tasks register themselves, via a call to add_task/1, and then |
| % update their status properties via update/1. The status of a task is a |
| % list of properties. Each property is a tuple, with the first element being |
| % either an atom or a binary and the second element must be an EJSON value. When |
| % a task updates its status, it can override some or all of its properties. |
| % The properties {started_on, UnitTimestamp}, {updated_on, UnixTimestamp} and |
| % {pid, ErlangPid} are automatically added by this module. |
| % When a tracked task dies, its status will be automatically removed from |
| % memory. To get the tasks list, call the all/0 function. |
| |
| -export([start_link/0, stop/0]). |
| -export([all/0, add_task/1, update/1, get/1, set_update_frequency/1]). |
| -export([is_task_added/0]). |
| |
| -export([init/1, terminate/2, code_change/3]). |
| -export([handle_call/3, handle_cast/2, handle_info/2]). |
| |
| -include_lib("couch/include/couch_db.hrl"). |
| |
| -define(set(L, K, V), lists:keystore(K, 1, L, {K, V})). |
| |
| |
| start_link() -> |
| gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). |
| |
| |
| stop() -> |
| gen_server:cast(?MODULE, stop). |
| |
| |
| all() -> |
| gen_server:call(?MODULE, all). |
| |
| |
| add_task(Props) -> |
| put(task_status_update, {{0, 0, 0}, 0}), |
| Ts = timestamp(), |
| TaskProps = lists:ukeysort( |
| 1, [{started_on, Ts}, {updated_on, Ts} | Props]), |
| put(task_status_props, TaskProps), |
| gen_server:call(?MODULE, {add_task, TaskProps}). |
| |
| |
| is_task_added() -> |
| is_list(erlang:get(task_status_props)). |
| |
| |
| set_update_frequency(Msecs) -> |
| put(task_status_update, {{0, 0, 0}, Msecs * 1000}). |
| |
| |
| update(Props) -> |
| MergeProps = lists:ukeysort(1, Props), |
| CurrProps = erlang:get(task_status_props), |
| TaskProps = lists:ukeymerge(1, MergeProps, CurrProps), |
| case TaskProps == CurrProps of |
| true -> |
| maybe_persist(TaskProps); |
| false -> |
| persist(TaskProps) |
| end. |
| |
| |
| get(Props) when is_list(Props) -> |
| TaskProps = erlang:get(task_status_props), |
| [couch_util:get_value(P, TaskProps) || P <- Props]; |
| get(Prop) -> |
| TaskProps = erlang:get(task_status_props), |
| couch_util:get_value(Prop, TaskProps). |
| |
| |
| maybe_persist(TaskProps) -> |
| {LastUpdateTime, Frequency} = erlang:get(task_status_update), |
| case timer:now_diff(Now = os:timestamp(), LastUpdateTime) >= Frequency of |
| true -> |
| put(task_status_update, {Now, Frequency}), |
| persist(TaskProps); |
| false -> |
| ok |
| end. |
| |
| |
| persist(TaskProps0) -> |
| TaskProps = ?set(TaskProps0, updated_on, timestamp(os:timestamp())), |
| put(task_status_props, TaskProps), |
| gen_server:cast(?MODULE, {update_status, self(), TaskProps}). |
| |
| |
| 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, TaskProps}, {From, _}, Server) -> |
| case ets:lookup(?MODULE, From) of |
| [] -> |
| true = ets:insert(?MODULE, {From, TaskProps}), |
| erlang:monitor(process, From), |
| {reply, ok, Server}; |
| [_] -> |
| {reply, {add_task_error, already_registered}, Server} |
| end; |
| handle_call(all, _, Server) -> |
| All = [ |
| [{pid, ?l2b(pid_to_list(Pid))} | TaskProps] |
| || |
| {Pid, TaskProps} <- ets:tab2list(?MODULE) |
| ], |
| {reply, All, Server}. |
| |
| |
| handle_cast({update_status, Pid, NewProps}, Server) -> |
| case ets:lookup(?MODULE, Pid) of |
| [{Pid, _CurProps}] -> |
| couch_log:debug("New task status for ~p: ~p", [Pid, NewProps]), |
| true = ets:insert(?MODULE, {Pid, NewProps}); |
| _ -> |
| % Task finished/died in the meanwhile and we must have received |
| % a monitor message before this call - ignore. |
| ok |
| end, |
| {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}. |
| |
| |
| timestamp() -> |
| timestamp(os:timestamp()). |
| |
| timestamp({Mega, Secs, _}) -> |
| Mega * 1000000 + Secs. |