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Diffstat (limited to 'src/couchdb/couch_task_status.erl')
-rw-r--r-- | src/couchdb/couch_task_status.erl | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/src/couchdb/couch_task_status.erl b/src/couchdb/couch_task_status.erl new file mode 100644 index 00000000..a0ef490a --- /dev/null +++ b/src/couchdb/couch_task_status.erl @@ -0,0 +1,97 @@ +% 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,init/1,terminate/2,handle_call/3,handle_cast/2,handle_info/2, + code_change/3,add_task/3,update/1,update/2,all/0,set_update_frequency/1]). + +-include("couch_db.hrl"). + +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + +to_binary(L) when is_list(L) -> + ?l2b(L); +to_binary(B) when is_binary(B) -> + B. + +add_task(Type, TaskName, StatusText) -> + put(task_status_update, {{0,0,0}, 0}), + gen_server:call(?MODULE, {add_task, to_binary(Type), + to_binary(TaskName), to_binary(StatusText)}). + +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}), + gen_server:cast(?MODULE, {update_status, self(), ?l2b(io_lib:format(Format, Data))}); + false -> + ok + end. + + +% returns a list of proplists. Each proplist describes a running task. +all() -> + [[{type,Type}, + {task,Task}, + {status,Status}, + {pid,?l2b(pid_to_list(Pid))}] || + {Pid, {Type,Task,Status}} <- ets:tab2list(tasks_by_pid)]. + +init([]) -> + % read configuration settings and register for configuration changes + ets:new(tasks_by_pid, [ordered_set, protected, named_table]), + {ok, nil}. + +terminate(_Reason,_State) -> + ok. + + +handle_call({add_task,Type,TaskName,StatusText}, {From, _}, Server) -> + case ets:lookup(tasks_by_pid, From) of + [] -> + true = ets:insert(tasks_by_pid, {From,{Type,TaskName,StatusText}}), + erlang:monitor(process, From), + {reply, ok, Server}; + [_] -> + {reply, {add_task_error, already_registered}, Server} + end. + +handle_cast({update_status, Pid, StatusText}, Server) -> + [{Pid, {Type,TaskName,_StatusText}}] = ets:lookup(tasks_by_pid, Pid), + true = ets:insert(tasks_by_pid, {Pid, {Type,TaskName,StatusText}}), + {noreply, Server}. + +handle_info({'DOWN', _MonitorRef, _Type, Pid, _Info}, Server) -> + ets:delete(tasks_by_pid, Pid), + {noreply, Server}. + +code_change(_OldVsn, State, _Extra) -> + {ok, State}. + + |