1 files changed, 124 insertions, 0 deletions
diff --git a/apps/couch/src/couch_task_status.erl b/apps/couch/src/couch_task_status.erl
new file mode 100644
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+++ b/apps/couch/src/couch_task_status.erl
@@ -0,0 +1,124 @@
+% 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),
+    ?LOG_DEBUG("New task status for ~s: ~s",[TaskName, StatusText]),
+    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}.
+