From e50f1cf9848bc5545852fbc1552b29a83041496a Mon Sep 17 00:00:00 2001
From: Robert Newson <rnewson@apache.org>
Date: Fri, 11 Sep 2015 17:22:01 +0100
Subject: [PATCH] Allow filtering of active tasks by property

COUCHDB-2807
---
 src/couch_httpd_misc_handlers.erl |  4 ++++
 src/couch_task_status.erl         | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/couch_httpd_misc_handlers.erl b/src/couch_httpd_misc_handlers.erl
index 10d6d9ed..e2c58c98 100644
--- a/src/couch_httpd_misc_handlers.erl
+++ b/src/couch_httpd_misc_handlers.erl
@@ -96,6 +96,10 @@ handle_all_dbs_req(Req) ->
     send_method_not_allowed(Req, "GET,HEAD").
 
 
+handle_task_status_req(#httpd{method='GET', path_parts=[_, K, V]}=Req) ->
+    ok = couch_httpd:verify_is_server_admin(Req),
+    % convert the list of prop lists to a list of json objects
+    send_json(Req, [{Props} || Props <- couch_task_status:filter(K, V)]);
 handle_task_status_req(#httpd{method='GET'}=Req) ->
     ok = couch_httpd:verify_is_server_admin(Req),
     % convert the list of prop lists to a list of json objects
diff --git a/src/couch_task_status.erl b/src/couch_task_status.erl
index 4083c3f8..7cf54263 100644
--- a/src/couch_task_status.erl
+++ b/src/couch_task_status.erl
@@ -28,6 +28,7 @@
 -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([filter/2]).
 
 -export([init/1, terminate/2, code_change/3]).
 -export([handle_call/3, handle_cast/2, handle_info/2]).
@@ -49,6 +50,10 @@ all() ->
     gen_server:call(?MODULE, all).
 
 
+filter(Key, Value) ->
+    gen_server:call(?MODULE, {filter, Key, Value}).
+
+
 add_task(Props) ->
     put(task_status_update, {{0, 0, 0}, 0}),
     Ts = timestamp(),
@@ -122,6 +127,14 @@ handle_call({add_task, TaskProps}, {From, _}, Server) ->
     [_] ->
         {reply, {add_task_error, already_registered}, Server}
     end;
+handle_call({filter, Key, Value}, _, Server) ->
+    All = [
+        [{pid, ?l2b(pid_to_list(Pid))} | TaskProps]
+        ||
+        {Pid, TaskProps} <- ets:tab2list(?MODULE),
+        filter_task(Key, Value, TaskProps)
+    ],
+    {reply, All, Server};
 handle_call(all, _, Server) ->
     All = [
         [{pid, ?l2b(pid_to_list(Pid))} | TaskProps]
@@ -130,6 +143,12 @@ handle_call(all, _, Server) ->
     ],
     {reply, All, Server}.
 
+filter_task(Key, Value, TaskProps) ->
+    Key1 = couch_util:to_list(Key),
+    Value1 = couch_util:to_list(Value),
+    TaskProps1 = [{couch_util:to_list(K), couch_util:to_list(V)}
+        || {K, V} <- TaskProps],
+    couch_util:get_value(Key1, TaskProps1) =:= Value1.
 
 handle_cast({update_status, Pid, NewProps}, Server) ->
     case ets:lookup(?MODULE, Pid) of