reorganize couch .erl and driver code into rebar layout

1 files changed, 136 insertions, 0 deletions

diff --git a/apps/couch/src/couch_stats_collector.erl b/apps/couch/src/couch_stats_collector.erl
new file mode 100644
index 00000000..f7b9bb48
--- /dev/null
+++ b/apps/couch/src/couch_stats_collector.erl
@@ -0,0 +1,136 @@
+% 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.
+
+% todo
+% - remove existance check on increment(), decrement() and record(). have
+%   modules initialize counters on startup.
+
+-module(couch_stats_collector).
+
+-behaviour(gen_server).
+
+-export([start/0, stop/0]).
+-export([all/0, all/1, get/1, increment/1, decrement/1, record/2, clear/1]).
+-export([track_process_count/1, track_process_count/2]).
+
+-export([init/1, terminate/2, code_change/3]).
+-export([handle_call/3, handle_cast/2, handle_info/2]).
+
+-define(HIT_TABLE, stats_hit_table).
+-define(ABS_TABLE, stats_abs_table).
+
+start() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+stop() ->
+    gen_server:call(?MODULE, stop).
+
+all() ->
+    ets:tab2list(?HIT_TABLE) ++ abs_to_list().
+
+all(Type) ->
+    case Type of
+        incremental -> ets:tab2list(?HIT_TABLE);
+        absolute -> abs_to_list()
+    end.
+
+get(Key) ->
+    case ets:lookup(?HIT_TABLE, Key) of
+        [] ->
+            case ets:lookup(?ABS_TABLE, Key) of
+                [] ->
+                    nil;
+                AbsVals ->
+                    lists:map(fun({_, Value}) -> Value end, AbsVals)
+            end;
+        [{_, Counter}] ->
+            Counter
+    end.
+
+increment(Key) ->
+    Key2 = make_key(Key),
+    case catch ets:update_counter(?HIT_TABLE, Key2, 1) of
+        {'EXIT', {badarg, _}} ->
+            catch ets:insert(?HIT_TABLE, {Key2, 1}),
+            ok;
+        _ ->
+            ok
+    end.
+
+decrement(Key) ->
+    Key2 = make_key(Key),
+    case catch ets:update_counter(?HIT_TABLE, Key2, -1) of
+        {'EXIT', {badarg, _}} ->
+            catch ets:insert(?HIT_TABLE, {Key2, -1}),
+            ok;
+        _ -> ok
+    end.
+
+record(Key, Value) ->
+    catch ets:insert(?ABS_TABLE, {make_key(Key), Value}).
+
+clear(Key) ->
+    catch ets:delete(?ABS_TABLE, make_key(Key)).
+
+track_process_count(Stat) ->
+    track_process_count(self(), Stat).
+
+track_process_count(Pid, Stat) ->
+    MonitorFun = fun() ->
+        Ref = erlang:monitor(process, Pid),
+        receive {'DOWN', Ref, _, _, _} -> ok end,
+        couch_stats_collector:decrement(Stat)
+    end,
+    case (catch couch_stats_collector:increment(Stat)) of
+        ok -> spawn(MonitorFun);
+        _ -> ok
+    end.
+
+
+init(_) ->
+    ets:new(?HIT_TABLE, [named_table, set, public]),
+    ets:new(?ABS_TABLE, [named_table, duplicate_bag, public]),
+    {ok, nil}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+handle_call(stop, _, State) ->
+    {stop, normal, stopped, State}.
+
+handle_cast(foo, State) ->
+    {noreply, State}.
+
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+code_change(_OldVersion, State, _Extra) ->
+    {ok, State}.
+
+
+make_key({Module, Key}) when is_integer(Key) ->
+    {Module, list_to_atom(integer_to_list(Key))};
+make_key(Key) ->
+    Key.
+
+abs_to_list() ->
+    SortedKVs = lists:sort(ets:tab2list(?ABS_TABLE)),
+    lists:foldl(fun({Key, Val}, Acc) ->
+        case Acc of
+            [] ->
+                [{Key, [Val]}];
+            [{Key, Prev} | Rest] ->
+                [{Key, [Val | Prev]} | Rest];
+            Others ->
+                [{Key, [Val]} | Others]
+        end
+    end, [], SortedKVs).
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