1 files changed, 40 insertions, 0 deletions
diff --git a/apps/rexi/src/rexi_monitor.erl b/apps/rexi/src/rexi_monitor.erl
new file mode 100644
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+++ b/apps/rexi/src/rexi_monitor.erl
@@ -0,0 +1,40 @@
+-module(rexi_monitor).
+-export([start/1, stop/1]).
+
+-include_lib("eunit/include/eunit.hrl").
+
+%% @doc spawn_links a process which monitors the supplied list of items and
+%% returns the process ID.  If a monitored process exits, the caller will
+%% receive a {rexi_DOWN, MonitoringPid, DeadPid, Reason} message.
+-spec start([pid() | atom() | {atom(),node()}]) -> pid().
+start(Procs) ->
+    Parent = self(),
+    spawn_link(fun() ->
+        [erlang:monitor(process, P) || P <- Procs],
+        wait_monitors(Parent)
+    end).
+
+%% @doc Cleanly shut down the monitoring process and flush all rexi_DOWN
+%% messages from our mailbox.
+-spec stop(pid()) -> ok.
+stop(MonitoringPid) ->
+    MonitoringPid ! {self(), shutdown},
+    flush_down_messages().
+
+%% internal functions %%
+
+wait_monitors(Parent) ->
+    receive
+    {'DOWN', _, process, Pid, Reason} ->
+        Parent ! {rexi_DOWN, self(), Pid, Reason},
+        wait_monitors(Parent);
+    {Parent, shutdown} ->
+        ok
+    end.
+
+flush_down_messages() ->
+    receive {rexi_DOWN, _, _, _} ->
+        flush_down_messages()
+    after 0 ->
+        ok
+    end.