Make couch_stream monitor the stream opener
This commit fixes a process leak which would happen when a process
opened a couch_stream and exited with reason normal before closing
the stream.
This patch makes the couch_stream gen_server monitor the process
which opens the stream. When that monitor sends an exit signal
the couch_stream gen_server is stopped and the process dies.
Closes COUCHDB-2365
diff --git a/src/couch_stream.erl b/src/couch_stream.erl
index e71542c..6877f0f 100644
--- a/src/couch_stream.erl
+++ b/src/couch_stream.erl
@@ -29,6 +29,7 @@
-record(stream,
{fd = 0,
+ opener_monitor,
written_pointers=[],
buffer_list = [],
buffer_len = 0,
@@ -50,7 +51,7 @@
open(Fd, []).
open(Fd, Options) ->
- gen_server:start_link(couch_stream, {Fd, Options}, []).
+ gen_server:start_link(couch_stream, {Fd, self(), Options}, []).
close(Pid) ->
gen_server:call(Pid, close, infinity).
@@ -197,7 +198,7 @@
gen_server:call(Pid, {write, Bin}, infinity).
-init({Fd, Options}) ->
+init({Fd, OpenerPid, Options}) ->
{EncodingFun, EndEncodingFun} =
case couch_util:get_value(encoding, Options, identity) of
identity ->
@@ -207,6 +208,7 @@
end,
{ok, #stream{
fd=Fd,
+ opener_monitor=erlang:monitor(process, OpenerPid),
md5=couch_util:md5_init(),
identity_md5=couch_util:md5_init(),
encoding_fun=EncodingFun,
@@ -266,6 +268,7 @@
handle_call(close, _From, Stream) ->
#stream{
fd = Fd,
+ opener_monitor = MonRef,
written_len = WrittenLen,
written_pointers = Written,
buffer_list = Buffer,
@@ -288,6 +291,7 @@
StreamLen = WrittenLen + iolist_size(WriteBin2),
{StreamInfo, StreamLen, IdenLen, Md5Final, IdenMd5Final}
end,
+ erlang:demonitor(MonRef),
{stop, normal, Result, Stream}.
handle_cast(_Msg, State) ->
@@ -296,5 +300,7 @@
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
+handle_info({'DOWN', Ref, _, _, _}, #stream{opener_monitor=Ref} = State) ->
+ {stop, normal, State};
handle_info(_Info, State) ->
{noreply, State}.
diff --git a/test/couch_stream_tests.erl b/test/couch_stream_tests.erl
index 3e84ca0..e12e714 100644
--- a/test/couch_stream_tests.erl
+++ b/test/couch_stream_tests.erl
@@ -38,7 +38,8 @@
fun should_return_stream_size_on_close/1,
fun should_return_valid_pointers/1,
fun should_recall_last_pointer_position/1,
- fun should_stream_more_with_4K_chunk_size/1
+ fun should_stream_more_with_4K_chunk_size/1,
+ fun should_stop_on_normal_exit_of_stream_opener/1
]
}
}.
@@ -94,6 +95,21 @@
?_assertMatch({[{0, 4100}, {4106, 1020}], 5120, _, _, _},
couch_stream:close(Stream)).
+should_stop_on_normal_exit_of_stream_opener({Fd, _}) ->
+ RunnerPid = self(),
+ OpenerPid = spawn(
+ fun() ->
+ {ok, StreamPid} = couch_stream:open(Fd),
+ RunnerPid ! {pid, StreamPid}
+ end),
+ StreamPid = receive
+ {pid, StreamPid0} -> StreamPid0
+ end,
+ % Confirm the validity of the test by verifying the stream opener has died
+ ?_assertNot(is_process_alive(OpenerPid)),
+ % Verify the stream itself has also died
+ ?_assertNot(is_process_alive(StreamPid)).
+
read_all(Fd, PosList) ->
Data = couch_stream:foldl(Fd, PosList, fun(Bin, Acc) -> [Bin, Acc] end, []),
