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willholley pushed a commit to branch wh/connect_to
in repository https://gitbox.apache.org/repos/asf/couchdb.git
The following commit(s) were added to refs/heads/wh/connect_to by this push:
new 904040b27 cache the parsed config
904040b27 is described below
commit 904040b27faafea7d280a8383de267d3a733f722
Author: Will Holley <[email protected]>
AuthorDate: Tue May 5 13:59:06 2026 +0100
cache the parsed config
Cached the parsed dns_overrides configuration.
I did consider adding per-connection caching as
well, but this seemed to be of limited benefit
in microbenchmarks. Adding the persistent_term
cache yields approx a 3x performance improvement
in resolution time (amounts to 150ms over
10k resolutions on my machine).
---
src/couch_replicator/priv/stats_descriptions.cfg | 4 +++
src/couch_replicator/src/couch_replicator_dns.erl | 29 ++++++++++++++++++----
.../src/couch_replicator_scheduler.erl | 4 +++
.../eunit/couch_replicator_dns_override_tests.erl | 3 +++
.../test/eunit/couch_replicator_dns_tests.erl | 3 ++-
5 files changed, 37 insertions(+), 6 deletions(-)
diff --git a/src/couch_replicator/priv/stats_descriptions.cfg
b/src/couch_replicator/priv/stats_descriptions.cfg
index 7edc87941..f7059e541 100644
--- a/src/couch_replicator/priv/stats_descriptions.cfg
+++ b/src/couch_replicator/priv/stats_descriptions.cfg
@@ -142,3 +142,7 @@
{type, counter},
{desc, <<"number of times a worker is gracefully shut down">>}
]}.
+{[couch_replicator, dns_overrides_applied], [
+ {type, counter},
+ {desc, <<"number of times DNS overrides were applied to replication
requests">>}
+]}.
diff --git a/src/couch_replicator/src/couch_replicator_dns.erl
b/src/couch_replicator/src/couch_replicator_dns.erl
index 9ff842b0e..7af377655 100644
--- a/src/couch_replicator/src/couch_replicator_dns.erl
+++ b/src/couch_replicator/src/couch_replicator_dns.erl
@@ -15,6 +15,7 @@
-include_lib("ibrowse/include/ibrowse.hrl").
-export([
+ init/0,
resolve_host/1,
apply_dns_override/2,
add_sni_option/2,
@@ -31,6 +32,19 @@
-type dns_override() :: {binary(), binary()}.
+-define(DNS_OVERRIDES_KEY, {?MODULE, dns_overrides}).
+
+%% Initialize DNS overrides cache
+-spec init() -> ok.
+init() ->
+ Overrides =
+ case config:get("replicator", "dns_overrides", undefined) of
+ undefined -> [];
+ ConfigStr -> parse_config(ConfigStr)
+ end,
+ persistent_term:put(?DNS_OVERRIDES_KEY, Overrides),
+ ok.
+
-spec resolve_host(string()) -> {string(), string() | undefined}.
resolve_host(Host) ->
case find_override(list_to_binary(Host), get_overrides()) of
@@ -42,11 +56,15 @@ resolve_host(Host) ->
-spec get_overrides() -> [dns_override()].
get_overrides() ->
- case config:get("replicator", "dns_overrides", undefined) of
- undefined ->
- [];
- ConfigStr ->
- parse_config(ConfigStr)
+ try
+ persistent_term:get(?DNS_OVERRIDES_KEY, [])
+ catch
+ error:badarg ->
+ % not initialized yet, fall back to reading config
+ case config:get("replicator", "dns_overrides", undefined) of
+ undefined -> [];
+ ConfigStr -> parse_config(ConfigStr)
+ end
end.
-spec parse_config(string()) -> [dns_override()].
@@ -168,6 +186,7 @@ apply_override_options(Opts, Protocol, TargetHost,
OriginalHost) ->
"DNS override (~p): ~s -> ~s",
[Protocol, OriginalHost, TargetHost]
),
+ couch_stats:increment_counter([couch_replicator, dns_overrides_applied]),
% Add connect_to option
Opts1 = [{connect_to, TargetHost} | Opts],
% Add SNI for HTTPS if OriginalHost is a hostname (not IP)
diff --git a/src/couch_replicator/src/couch_replicator_scheduler.erl
b/src/couch_replicator/src/couch_replicator_scheduler.erl
index 9eb0b4723..eae1a321d 100644
--- a/src/couch_replicator/src/couch_replicator_scheduler.erl
+++ b/src/couch_replicator/src/couch_replicator_scheduler.erl
@@ -229,6 +229,7 @@ init(_) ->
],
?MODULE = ets:new(?MODULE, EtsOpts),
ok = couch_replicator_share:init(),
+ ok = couch_replicator_dns:init(),
ok = config:listen_for_changes(?MODULE, nil),
Interval = get_interval_msec(),
MaxJobs = config:get_integer("replicator", "max_jobs", ?DEFAULT_MAX_JOBS),
@@ -385,6 +386,9 @@ handle_config_change("replicator", "interval", V, _, S) ->
handle_config_change("replicator", "max_history", V, _, S) ->
ok = gen_server:cast(?MODULE, {set_max_history, list_to_integer(V)}),
{ok, S};
+handle_config_change("replicator", "dns_overrides", _, _, S) ->
+ ok = couch_replicator_dns:init(),
+ {ok, S};
handle_config_change("replicator.shares", Key, deleted, _, S) ->
ok = gen_server:cast(?MODULE, {reset_shares, list_to_binary(Key)}),
{ok, S};
diff --git
a/src/couch_replicator/test/eunit/couch_replicator_dns_override_tests.erl
b/src/couch_replicator/test/eunit/couch_replicator_dns_override_tests.erl
index 677f8b6fd..bc3844544 100644
--- a/src/couch_replicator/test/eunit/couch_replicator_dns_override_tests.erl
+++ b/src/couch_replicator/test/eunit/couch_replicator_dns_override_tests.erl
@@ -46,6 +46,9 @@ should_replicate_with_dns_override({_Ctx, {Source, Target}})
->
OverrideConfig = "example.com:" ++ SourceHost,
config:set("replicator", "dns_overrides", OverrideConfig, false),
+ % reinitialize DNS cache to pick up the new config
+ couch_replicator_dns:init(),
+
% replace source host with example.com
OverrideUrl = re:replace(SourceUrl, SourceHost, "example.com", [{return,
binary}]),
diff --git a/src/couch_replicator/test/eunit/couch_replicator_dns_tests.erl
b/src/couch_replicator/test/eunit/couch_replicator_dns_tests.erl
index db23d2b5b..c40500b10 100644
--- a/src/couch_replicator/test/eunit/couch_replicator_dns_tests.erl
+++ b/src/couch_replicator/test/eunit/couch_replicator_dns_tests.erl
@@ -114,7 +114,8 @@ resolve_host_test_() ->
"*.example.test:proxy.internal,foo.bar.com:127.0.0.1";
(_, _, Default) ->
Default
- end)
+ end),
+ couch_replicator_dns:init()
end,
fun(_) ->
meck:unload(config)
