File 2834-Improve-colliding-updates.patch of Package erlang
From 7383df68376c6d0418a8e89869b973943046df1e Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Sat, 15 Feb 2020 17:10:54 +0100
Subject: [PATCH 4/6] Improve colliding updates
Read file info from server, not from client. All reads goes through
the same server anyway, so there is no point in doing it in the client.
Check timestamp from client. When enough time has passed request update.
Pass timestamp to server that can check if the update request is late,
and avoid tightly repeating updates from multiple colliding clients.
---
lib/kernel/src/inet_db.erl | 137 +++++++++++++++++++++++++--------------------
1 file changed, 75 insertions(+), 62 deletions(-)
diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl
index d21e419ed9..33b10f54a2 100644
--- a/lib/kernel/src/inet_db.erl
+++ b/lib/kernel/src/inet_db.erl
@@ -229,9 +229,11 @@ set_edns(Version) -> res_option(edns, Version).
set_udp_payload_size(Size) -> res_option(udp_payload_size, Size).
-set_resolv_conf(Fname) -> res_option(resolv_conf, Fname).
+set_resolv_conf(Fname) when is_list(Fname) ->
+ res_option(resolv_conf, Fname).
-set_hosts_file(Fname) -> res_option(hosts_file, Fname).
+set_hosts_file(Fname) when is_list(Fname) ->
+ res_option(hosts_file, Fname).
get_hosts_file() ->
get_rc_hosts([], [], inet_hosts_file_byaddr).
@@ -495,41 +497,19 @@ socks_option(noproxy) -> db_get(socks5_noproxy).
gethostname() -> db_get(hostname).
res_update_conf() ->
- res_update(res_resolv_conf, res_resolv_conf_tm, res_resolv_conf_info,
- set_resolv_conf_tm, fun set_resolv_conf/1).
+ res_update(resolv_conf, res_resolv_conf_tm).
res_update_hosts() ->
- res_update(res_hosts_file, res_hosts_file_tm, res_hosts_file_info,
- set_hosts_file_tm, fun set_hosts_file/1).
+ res_update(hosts_file, res_hosts_file_tm).
-res_update(Tag, TagTm, TagInfo, TagSetTm, SetFun) ->
+res_update(Option, TagTm) ->
case db_get(TagTm) of
undefined -> ok;
- TM ->
+ Tm ->
case times() of
- Now when Now >= TM + ?RES_FILE_UPDATE_TM ->
- case db_get(Tag) of
- undefined ->
- SetFun("");
- "" ->
- SetFun("");
- File ->
- case erl_prim_loader:read_file_info(File) of
- {ok, Finfo0} ->
- Finfo =
- Finfo0#file_info{access = undefined,
- atime = undefined},
- case db_get(TagInfo) of
- Finfo ->
- call({TagSetTm, Now});
- _ ->
- SetFun(File)
- end;
- _ ->
- call({TagSetTm, Now}),
- error
- end
- end;
+ Now when Now >= Tm + ?RES_FILE_UPDATE_TM ->
+ %% Enough time has passed - request server to update
+ res_option(Option, Tm);
_ -> ok
end
end.
@@ -979,12 +959,12 @@ handle_call(Request, From, #state{db=Db}=State) ->
Option, Fname, res_resolv_conf_tm, res_resolv_conf_info,
undefined, From, State);
- {res_set, hosts_file=Option, Fname} ->
+ {res_set, hosts_file=Option, Fname_or_Tm} ->
handle_set_file(
- Option, Fname, res_hosts_file_tm, res_hosts_file_info,
- fun (Bin) ->
+ Option, Fname_or_Tm, res_hosts_file_tm, res_hosts_file_info,
+ fun (File, Bin) ->
case inet_parse:hosts(
- Fname, {chars,Bin}) of
+ File, {chars,Bin}) of
{ok,Opts} ->
[{load_hosts_file,Opts}];
_ -> error
@@ -992,12 +972,12 @@ handle_call(Request, From, #state{db=Db}=State) ->
end,
From, State);
%%
- {res_set, resolv_conf=Option, Fname} ->
+ {res_set, resolv_conf=Option, Fname_or_Tm} ->
handle_set_file(
- Option, Fname, res_resolv_conf_tm, res_resolv_conf_info,
- fun (Bin) ->
+ Option, Fname_or_Tm, res_resolv_conf_tm, res_resolv_conf_info,
+ fun (File, Bin) ->
case inet_parse:resolv(
- Fname, {chars,Bin}) of
+ File, {chars,Bin}) of
{ok,Opts} ->
Search =
lists:foldl(
@@ -1170,15 +1150,37 @@ terminate(_Reason, State) ->
%%% Internal functions
%%%----------------------------------------------------------------------
-handle_set_file(Option, Fname, TagTm, TagInfo, ParseFun, From,
- #state{db=Db}=State) ->
+handle_set_file(
+ Option, Tm, TagTm, TagInfo, ParseFun, From, #state{db=Db}=State)
+ when is_integer(Tm) ->
+ %%
+ %% Maybe update file content
+ %%
+ case ets:lookup(Db, TagTm) of
+ [] ->
+ %% Option no longer set - ignore update
+ {reply, ok, State};
+ [{_, Tm}] ->
+ %% Current update request
+ [{_, File}] = ets:lookup(Db, res_optname(Option)),
+ [{_, Finfo}] = ets:lookup(Db, TagInfo),
+ handle_update_file(
+ Finfo, File, TagTm, TagInfo, ParseFun, From, State);
+ [_] ->
+ %% Late request - ignore update
+ {reply, ok, State}
+ end;
+handle_set_file(
+ Option, Fname, TagTm, TagInfo, ParseFun, From, #state{db=Db}=State) ->
case res_check_option(Option, Fname) of
true when Fname =:= "" ->
+ %% Delete file content and monitor
ets:insert(Db, {res_optname(Option), Fname}),
ets:delete(Db, TagInfo),
ets:delete(Db, TagTm),
- handle_set_file(ParseFun, <<>>, From, State);
+ handle_set_file(ParseFun, Fname, <<>>, From, State);
true when ParseFun =:= undefined ->
+ %% Set file name and monitor
File = filename:flatten(Fname),
ets:insert(Db, {res_optname(Option), File}),
ets:insert(Db, {TagInfo, undefined}),
@@ -1186,37 +1188,48 @@ handle_set_file(Option, Fname, TagTm, TagInfo, ParseFun, From,
ets:insert(Db, {TagTm, TimeZero}),
{reply,ok,State};
true ->
+ %% Set file name and monitor, read content
File = filename:flatten(Fname),
ets:insert(Db, {res_optname(Option), File}),
- Bin =
- case erl_prim_loader:read_file_info(File) of
- {ok, Finfo0} ->
- Finfo = Finfo0#file_info{access = undefined,
- atime = undefined},
- ets:insert(Db, {TagInfo, Finfo}),
- ets:insert(Db, {TagTm, times()}),
- case erl_prim_loader:get_file(File) of
- {ok, B, _} -> B;
- _ -> <<>>
- end;
- _ ->
- ets:insert(Db, {TagInfo, undefined}),
- TimeZero = - (?RES_FILE_UPDATE_TM + 1), % Early enough
- ets:insert(Db, {TagTm, TimeZero}),
- <<>>
- end,
- handle_set_file(ParseFun, Bin, From, State);
+ handle_update_file(
+ undefined, File, TagTm, TagInfo, ParseFun, From, State);
false -> {reply,error,State}
end.
-handle_set_file(ParseFun, Bin, From, State) ->
- case ParseFun(Bin) of
+handle_set_file(ParseFun, File, Bin, From, State) ->
+ case ParseFun(File, Bin) of
error ->
{reply,error,State};
Opts ->
handle_rc_list(Opts, From, State)
end.
+handle_update_file(
+ Finfo, File, TagTm, TagInfo, ParseFun, From, #state{db = Db} = State) ->
+ %%
+ %% Update file content if file has been updated
+ %%
+ case erl_prim_loader:read_file_info(File) of
+ {ok, Finfo} ->
+ %% No file update - we are done
+ {reply, ok, State};
+ {ok, Finfo_1} ->
+ %% File updated - read content
+ ets:insert(Db, {TagInfo, Finfo_1}),
+ ets:insert(Db, {TagTm, times()}),
+ Bin =
+ case erl_prim_loader:get_file(File) of
+ {ok, B, _} -> B;
+ _ -> <<>>
+ end,
+ handle_set_file(ParseFun, File, Bin, From, State);
+ _ ->
+ %% No file - clear content and reset monitor
+ ets:insert(Db, {TagInfo, undefined}),
+ ets:insert(Db, {TagTm, times()}),
+ handle_set_file(ParseFun, File, <<>>, From, State)
+ end.
+
%% Byname has lowercased names while Byaddr keep the name casing.
%% This is to be able to reconstruct the original /etc/hosts entry.
--
2.16.4
