Github user iilyak commented on a diff in the pull request:
https://github.com/apache/couchdb-couch-replicator/pull/38#discussion_r62203646
--- Diff: src/couch_replicator_rate_limiter.erl ---
@@ -0,0 +1,219 @@
+-module(couch_replicator_rate_limiter).
+-behaviour(gen_server).
+
+
+-include_lib("couch/include/couch_db.hrl").
+-include_lib("ibrowse/include/ibrowse.hrl").
+-include_lib("couch_replicator_api_wrap.hrl").
+
+
+-export([
+ start_link/0
+]).
+
+-export([
+ init/1,
+ terminate/2,
+ handle_call/3,
+ handle_cast/2,
+ handle_info/2,
+ code_change/3
+]).
+
+-export ([
+ maybe_start_rate_limiter/3,
+ maybe_decrement_rep_count/1,
+ maybe_delay_request/1
+ ]).
+
+-record(rep_limiter, {
+ requestCounter = 0,
+ lastUpdateTimestamp = 0,
+ pid,
+ replications = 0,
+ limit, % max requests
+ period % interval is in seconds
+}).
+
+
+%% For each unique host, an entry is a rep_limiter record
+-define(HOSTS, couch_replicator_limit_hosts).
+
+
+start_link() ->
+ gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+
+update_host(Host, Limit, Period) ->
+ gen_server:call(?MODULE, {update_host, Host, Limit, Period}, infinity).
+
+
+decrement_replications(Host) ->
+ gen_server:call(?MODULE, {decrement_replications, Host}, infinity).
+
+
+% gen_server functions.
+init([]) ->
+ process_flag(trap_exit, true),
+ ets:new(?HOSTS, [set, public, named_table]),
+ {ok, nil}.
+
+
+handle_call({update_host, Host, Limit, Period}, _From, State) ->
+ Reps = case ets:insert_new(?HOSTS, {Host, #rep_limiter{}}) of
+ true ->
+ % Brand new host for replication, need to spawn
+ % a new resetter process and initialize
+ LoopPid = spawn_link(fun() ->
+ reset_requests_loop(Host, Period)
+ end),
+ modify_host(Host, [{4, LoopPid}, {5, 1}, {6, Limit},
+ {7, Period}]),
+ 1;
+ false ->
+ % this allows the rate limit to be changed during replication
+ modify_host(Host, [{6, Limit}, {7, Period}]),
+ update_rep_count(Host, 1)
+ end,
+ {ok, Reps, State};
+
+
+handle_call({decrement_replications, Host}, _From, State) ->
+ Replications = case update_rep_count(Host, -1) of
+ Rep0 when Rep0 =< 0 ->
+ ResetPid = ets:lookup_element(?HOSTS, Host, 4),
+ % no more replications at this moment, stop resetter
+ % process and remove the host from the ets table
+ exit(ResetPid, stop_resetter),
+ remove_host(Host);
+ _ ->
+ ok % this shoulld be some error
+ end,
+ {ok, Replications, State}.
+
+
+handle_cast(_, State) ->
+ {noreply, State}.
+
+
+handle_info({'EXIT', _FromPid, stop_resetter}, State) ->
+ {noreply, State};
+
+handle_info({'EXIT', _FromPid, Reason}, State) ->
+ couch_log:error("couch_replicator_rate_limiter reset process
+ died abnormally due to: ~p", [Reason]),
+ {noreply, State}.
--- End diff --
Do you want to restart rate_limiter rest process here?
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