From cfd924076c91906ef13017ff212d0ba88fcefff1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Tue, 5 Mar 2013 15:53:10 +0100
Subject: kernel: Add application:ensure_started/1,2

Similar to application:start/1,2 except it returns 'ok' on already
started applications instead of {'error', {'already_started', ...}}.
---
 lib/kernel/src/application.erl | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

(limited to 'lib/kernel')

diff --git a/lib/kernel/src/application.erl b/lib/kernel/src/application.erl
index 6efc1b4499..5dd6b73857 100644
--- a/lib/kernel/src/application.erl
+++ b/lib/kernel/src/application.erl
@@ -22,6 +22,7 @@
 	 load/1, load/2, unload/1, takeover/2,
 	 which_applications/0, which_applications/1,
 	 loaded_applications/0, permit/2]).
+-export([ensure_started/1, ensure_started/2]).
 -export([set_env/3, set_env/4, unset_env/2, unset_env/3]).
 -export([get_env/1, get_env/2, get_env/3, get_all_env/0, get_all_env/1]).
 -export([get_key/1, get_key/2, get_all_key/0, get_all_key/1]).
@@ -135,6 +136,28 @@ start(Application, RestartType) ->
 	    Error
     end.
 
+-spec ensure_started(Application) -> 'ok' | {'error', Reason} when
+      Application :: atom(),
+      Reason :: term().
+
+ensure_started(Application) ->
+    ensure_started(Application, temporary).
+
+-spec ensure_started(Application, Type) -> 'ok' | {'error', Reason} when
+      Application :: atom(),
+      Type :: restart_type(),
+      Reason :: term().
+
+ensure_started(Application, RestartType) ->
+    case start(Application, RestartType) of
+	ok ->
+	    ok;
+	{error, {already_started, Application}} ->
+	    ok;
+	Error ->
+	    Error
+    end.
+
 -spec start_boot(Application :: atom()) -> 'ok' | {'error', term()}.
 
 start_boot(Application) ->
-- 
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