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File 1681-Replace-some-uses-of-ets-lookup-by-ets-lookup_elemen.patch of Package erlang (Revision 6af34d10e5fc1c974d15399d1aade82a)

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From 8134a8078433d46acb4e20df98ec7939845567e3 Mon Sep 17 00:00:00 2001
From: Robin Morisset <rmorisset@fb.com>
Date: Tue, 11 Oct 2022 15:45:15 +0200
Subject: [PATCH] Replace some uses of ets:lookup by ets:lookup_element in the
 stdlib

When only one field of an ETS record is needed, using ets:lookup_element is usually faster than ets:lookup.
This patch makes sure that we do so whenever possible, taking advantage of the recently landed
ets:lookup_element/4 (https://github.com/erlang/otp/pull/6234) in places.
---
 lib/asn1/src/asn1_db.erl                  | 11 ++++-------
 lib/kernel/src/application.erl            |  9 ++-------
 lib/kernel/src/application_controller.erl | 17 +++++++++--------
 lib/kernel/src/inet_db.erl                |  4 +---
 lib/kernel/src/pg.erl                     | 14 ++------------
 lib/stdlib/src/beam_lib.erl               |  3 +--
 6 files changed, 19 insertions(+), 39 deletions(-)

diff --git a/lib/asn1/src/asn1_db.erl b/lib/asn1/src/asn1_db.erl
index 7486fa2db9..28c1fc4563 100644
--- a/lib/asn1/src/asn1_db.erl
+++ b/lib/asn1/src/asn1_db.erl
@@ -82,11 +82,11 @@ loop(#state{parent = Parent, monitor = MRef, table = Table,
             includes = Includes} = State) ->
     receive
         {set, Mod, K2, V} ->
-            [{_, Modtab}] = ets:lookup(Table, Mod),
+            Modtab = ets:lookup_element(Table, Mod, 2),
             ets:insert(Modtab, {K2, V}),
             loop(State);
         {set, Mod, Kvs} ->
-            [{_, Modtab}] = ets:lookup(Table, Mod),
+            Modtab = ets:lookup_element(Table, Mod, 2),
             ets:insert(Modtab, Kvs),
             loop(State);
         {From, {get, Mod, K2}} ->
@@ -105,7 +105,7 @@ loop(#state{parent = Parent, monitor = MRef, table = Table,
             end,
             loop(State);
         {save, OutFile, Mod} ->
-            [{_,Mtab}] = ets:lookup(Table, Mod),
+            Mtab = ets:lookup_element(Table, Mod, 2),
 	    TempFile = OutFile ++ ".#temp",
             ok = ets:tab2file(Mtab, TempFile),
 	    ok = file:rename(TempFile, OutFile),
@@ -146,10 +146,7 @@ get_table(Table, Mod, Includes) ->
     end.
 
 lookup(Tab, K) ->
-    case ets:lookup(Tab, K) of
-        []      -> undefined;
-        [{K,V}] -> V
-    end.
+	ets:lookup_element(Tab, K, 2, undefined).
 
 info(EruleMaps) ->
     {asn1ct:vsn(),EruleMaps}.
diff --git a/lib/kernel/src/application.erl b/lib/kernel/src/application.erl
index 3eb87d73c7..1730e1e822 100644
--- a/lib/kernel/src/application.erl
+++ b/lib/kernel/src/application.erl
@@ -397,13 +397,8 @@ get_env(Application, Key) ->
       Def :: term(),
       Val :: term().
 
-get_env(Application, Key, Def) ->
-    case get_env(Application, Key) of
-    {ok, Val} ->
-        Val;
-    undefined ->
-        Def
-    end.
+get_env(Application, Key, Default) ->
+    application_controller:get_env(Application, Key, Default).
 
 -spec get_all_env() -> Env when
       Env :: [{Par :: atom(), Val :: term()}].
diff --git a/lib/kernel/src/application_controller.erl b/lib/kernel/src/application_controller.erl
index b82c3b0784..c5b4445bb8 100644
--- a/lib/kernel/src/application_controller.erl
+++ b/lib/kernel/src/application_controller.erl
@@ -27,7 +27,7 @@
 	 change_application_data/2, prep_config_change/0, config_change/1,
 	 which_applications/0, which_applications/1,
 	 loaded_applications/0, info/0, set_env/2,
-	 get_pid_env/2, get_env/2, get_pid_all_env/1, get_all_env/1,
+	 get_pid_env/2, get_env/2, get_env/3, get_pid_all_env/1, get_all_env/1,
 	 get_pid_key/2, get_key/2, get_pid_all_key/1, get_all_key/1,
 	 get_master/1, get_application/1, get_application_module/1,
 	 start_type/1, permit_application/2, do_config_diff/2,
@@ -343,11 +343,15 @@ get_pid_env(Master, Key) ->
     end.
 
 get_env(AppName, Key) ->
-    case ets:lookup(ac_tab, {env, AppName, Key}) of
-	[{_, Val}] -> {ok, Val};
-	_ -> undefined
+    NotFound = make_ref(),
+    case ets:lookup_element(ac_tab, {env, AppName, Key}, 2, NotFound) of
+        NotFound -> undefined;
+        Val -> {ok, Val}
     end.
 
+get_env(AppName, Key, Default) ->
+    ets:lookup_element(ac_tab, {env, AppName, Key}, 2, Default).
+
 get_pid_all_env(Master) ->
     case ets:match(ac_tab, {{application_master, '$1'}, Master}) of
 	[[AppName]] -> get_all_env(AppName);
@@ -442,10 +446,7 @@ start_type(Master) ->
 
 
 get_master(AppName) ->
-    case ets:lookup(ac_tab, {application_master, AppName}) of
-	[{_, Pid}] -> Pid;
-	_ -> undefined
-    end.
+    ets:lookup_element(ac_tab, {application_master, AppName}, 2, undefined).
 
 get_application(Master) ->
     case ets:match(ac_tab, {{application_master, '$1'}, Master}) of
diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl
index 408f563909..4937bc0751 100644
--- a/lib/kernel/src/inet_db.erl
+++ b/lib/kernel/src/inet_db.erl
@@ -579,9 +579,7 @@ res_update(Option, TagTm) ->
     end.
 
 db_get(Name) ->
-    try ets:lookup_element(inet_db, Name, 2)
-    catch error:badarg -> undefined
-    end.
+    ets:lookup_element(inet_db, Name, 2, undefined).
 
 add_rr(RR) ->
     %% Questionable if we need to support this;
diff --git a/lib/kernel/src/pg.erl b/lib/kernel/src/pg.erl
index 017b1942b4..94c9772468 100644
--- a/lib/kernel/src/pg.erl
+++ b/lib/kernel/src/pg.erl
@@ -203,12 +203,7 @@ get_members(Group) ->
 
 -spec get_members(Scope :: atom(), Group :: group()) -> [pid()].
 get_members(Scope, Group) ->
-    try
-        ets:lookup_element(Scope, Group, 2)
-    catch
-        error:badarg ->
-            []
-    end.
+    ets:lookup_element(Scope, Group, 2, []).
 
 %%--------------------------------------------------------------------
 %% @doc
@@ -219,12 +214,7 @@ get_local_members(Group) ->
 
 -spec get_local_members(Scope :: atom(), Group :: group()) -> [pid()].
 get_local_members(Scope, Group) ->
-    try
-        ets:lookup_element(Scope, Group, 3)
-    catch
-        error:badarg ->
-            []
-    end.
+    ets:lookup_element(Scope, Group, 3, []).
 
 %%--------------------------------------------------------------------
 %% @doc
diff --git a/lib/stdlib/src/beam_lib.erl b/lib/stdlib/src/beam_lib.erl
index 0753fbbd2b..b5249df414 100644
--- a/lib/stdlib/src/beam_lib.erl
+++ b/lib/stdlib/src/beam_lib.erl
@@ -832,8 +832,7 @@ symbol(_, AT, I1, I2, _I3, _Cnt) ->
     {atm(AT, I1), I2}.
 
 atm(AT, N) ->
-    [{_N, S}] = ets:lookup(AT, N),
-    S.
+    ets:lookup_element(AT, N, 2).
 
 %% AT is updated.
 ensure_atoms({empty, AT}, Cs) ->
-- 
2.35.3

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File 1681-Replace-some-uses-of-ets-lookup-by-ets-lookup_elemen.patch of Package erlang (Revision 6af34d10e5fc1c974d15399d1aade82a)

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