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Merge pull request #13391 from keynslug/perf/EMQX-12611/avoid-stream-shuffle 

perf(sessds): rotate through streams with iterators when fetching
This commit is contained in:
Andrew Mayorov 2024-07-03 17:46:29 +02:00 committed by GitHub
parent 45dbfb77e3 950f4d9483
commit 187f5e5936
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3 changed files with 223 additions and 58 deletions
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27
apps/emqx/src/emqx_persistent_session_ds.erl
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@ -182,6 +182,9 @@
shared_sub_s := shared_sub_state(),
%% Buffer:
inflight := emqx_persistent_session_ds_inflight:t(),
%% Last fetched stream:
%% Used as a continuation point for fair stream scheduling.
last_fetched_stream => emqx_persistent_session_ds_state:stream_key(),
%% In-progress replay:
%% List of stream replay states to be added to the inflight buffer.
replay => [{_StreamKey, stream_state()}, ...],
@ -984,26 +987,32 @@ do_ensure_all_iterators_closed(_DSSessionID) ->
%%--------------------------------------------------------------------
fetch_new_messages(Session0 = #{s := S0}, ClientInfo) ->
Streams = emqx_persistent_session_ds_stream_scheduler:find_new_streams(S0),
Session1 = fetch_new_messages(Streams, Session0, ClientInfo),
LFS = maps:get(last_fetched_stream, Session0, beginning),
ItStream = emqx_persistent_session_ds_stream_scheduler:iter_next_streams(LFS, S0),
BatchSize = get_config(ClientInfo, [batch_size]),
Session1 = fetch_new_messages(ItStream, BatchSize, Session0, ClientInfo),
#{s := S1, shared_sub_s := SharedSubS0} = Session1,
{S2, SharedSubS1} = emqx_persistent_session_ds_shared_subs:on_streams_replayed(S1, SharedSubS0),
Session1#{s => S2, shared_sub_s => SharedSubS1}.
fetch_new_messages([], Session, _ClientInfo) ->
Session;
fetch_new_messages([I | Streams], Session0 = #{inflight := Inflight}, ClientInfo) ->
BatchSize = get_config(ClientInfo, [batch_size]),
fetch_new_messages(ItStream0, BatchSize, Session0, ClientInfo) ->
#{inflight := Inflight} = Session0,
case emqx_persistent_session_ds_inflight:n_buffered(all, Inflight) >= BatchSize of
true ->
%% Buffer is full:
Session0;
false ->
Session = new_batch(I, BatchSize, Session0, ClientInfo),
fetch_new_messages(Streams, Session, ClientInfo)
case emqx_persistent_session_ds_stream_scheduler:next_stream(ItStream0) of
{StreamKey, Srs, ItStream} ->
Session1 = new_batch(StreamKey, Srs, BatchSize, Session0, ClientInfo),
Session = Session1#{last_fetched_stream => StreamKey},
fetch_new_messages(ItStream, BatchSize, Session, ClientInfo);
none ->
Session0
end
end.
new_batch({StreamKey, Srs0}, BatchSize, Session0 = #{s := S0}, ClientInfo) ->
new_batch(StreamKey, Srs0, BatchSize, Session0 = #{s := S0}, ClientInfo) ->
SN1 = emqx_persistent_session_ds_state:get_seqno(?next(?QOS_1), S0),
SN2 = emqx_persistent_session_ds_state:get_seqno(?next(?QOS_2), S0),
Srs1 = Srs0#srs{

154
apps/emqx/src/emqx_persistent_session_ds/emqx_persistent_session_ds_state.erl
View File

@ -39,7 +39,7 @@
-export([get_peername/1, set_peername/2]).
-export([get_protocol/1, set_protocol/2]).
-export([new_id/1]).
-export([get_stream/2, put_stream/3, del_stream/2, fold_streams/3, n_streams/1]).
-export([get_stream/2, put_stream/3, del_stream/2, fold_streams/3, iter_streams/2, n_streams/1]).
-export([get_seqno/2, put_seqno/3]).
-export([get_rank/2, put_rank/3, del_rank/2, fold_ranks/3]).
-export([
@ -66,11 +66,14 @@
n_awaiting_rel/1
]).
-export([iter_next/1]).
-export([make_session_iterator/0, session_iterator_next/2]).
-export_type([
t/0,
metadata/0,
iter/2,
seqno_type/0,
stream_key/0,
rank_key/0,
@ -89,6 +92,8 @@
-type message() :: emqx_types:message().
-opaque iter(K, V) :: gb_trees:iter(K, V).
-opaque session_iterator() :: emqx_persistent_session_ds:id() | '$end_of_table'.
%% Generic key-value wrapper that is used for exporting arbitrary
@ -113,7 +118,7 @@
-type pmap(K, V) ::
#pmap{
table :: atom(),
cache :: #{K => V},
cache :: #{K => V} | gb_trees:tree(K, V),
dirty :: #{K => dirty | del}
}.
@ -476,6 +481,14 @@ del_stream(Key, Rec) ->
fold_streams(Fun, Acc, Rec) ->
gen_fold(?streams, Fun, Acc, Rec).
-spec iter_streams(_StartAfter :: stream_key() | beginning, t()) ->
iter(stream_key(), emqx_persistent_session_ds:stream_state()).
iter_streams(After, Rec) ->
%% NOTE
%% No special handling for `beginning', as it always compares less
%% than any `stream_key()'.
gen_iter_after(?streams, After, Rec).
-spec n_streams(t()) -> non_neg_integer().
n_streams(Rec) ->
gen_size(?streams, Rec).
@ -534,6 +547,12 @@ n_awaiting_rel(Rec) ->
%%
-spec iter_next(iter(K, V)) -> {K, V, iter(K, V)} | none.
iter_next(It0) ->
gen_iter_next(It0).
%%
-spec make_session_iterator() -> session_iterator().
make_session_iterator() ->
mnesia:dirty_first(?session_tab).
@ -601,6 +620,14 @@ gen_size(Field, Rec) ->
check_sequence(Rec),
pmap_size(maps:get(Field, Rec)).
gen_iter_after(Field, After, Rec) ->
check_sequence(Rec),
pmap_iter_after(After, maps:get(Field, Rec)).
gen_iter_next(It) ->
%% NOTE: Currently, gbt iterators is the only type of iterators.
gbt_iter_next(It).
-spec update_pmaps(fun((pmap(_K, _V) | undefined, atom()) -> term()), map()) -> map().
update_pmaps(Fun, Map) ->
lists:foldl(
@ -619,7 +646,7 @@ update_pmaps(Fun, Map) ->
%% This functtion should be ran in a transaction.
-spec pmap_open(atom(), emqx_persistent_session_ds:id()) -> pmap(_K, _V).
pmap_open(Table, SessionId) ->
Clean = maps:from_list(kv_pmap_restore(Table, SessionId)),
Clean = cache_from_list(Table, kv_pmap_restore(Table, SessionId)),
#pmap{
table = Table,
cache = Clean,
@ -627,29 +654,29 @@ pmap_open(Table, SessionId) ->
}.
-spec pmap_get(K, pmap(K, V)) -> V | undefined.
pmap_get(K, #pmap{cache = Cache}) ->
maps:get(K, Cache, undefined).
pmap_get(K, #pmap{table = Table, cache = Cache}) ->
cache_get(Table, K, Cache).
-spec pmap_put(K, V, pmap(K, V)) -> pmap(K, V).
pmap_put(K, V, Pmap = #pmap{dirty = Dirty, cache = Cache}) ->
pmap_put(K, V, Pmap = #pmap{table = Table, dirty = Dirty, cache = Cache}) ->
Pmap#pmap{
cache = maps:put(K, V, Cache),
cache = cache_put(Table, K, V, Cache),
dirty = Dirty#{K => dirty}
}.
-spec pmap_del(K, pmap(K, V)) -> pmap(K, V).
pmap_del(
Key,
Pmap = #pmap{dirty = Dirty, cache = Cache}
Pmap = #pmap{table = Table, dirty = Dirty, cache = Cache}
) ->
Pmap#pmap{
cache = maps:remove(Key, Cache),
cache = cache_remove(Table, Key, Cache),
dirty = Dirty#{Key => del}
}.
-spec pmap_fold(fun((K, V, A) -> A), A, pmap(K, V)) -> A.
pmap_fold(Fun, Acc, #pmap{cache = Cache}) ->
maps:fold(Fun, Acc, Cache).
pmap_fold(Fun, Acc, #pmap{table = Table, cache = Cache}) ->
cache_fold(Table, Fun, Acc, Cache).
-spec pmap_commit(emqx_persistent_session_ds:id(), pmap(K, V)) -> pmap(K, V).
pmap_commit(
@ -660,7 +687,7 @@ pmap_commit(
(K, del) ->
kv_pmap_delete(Tab, SessionId, K);
(K, dirty) ->
V = maps:get(K, Cache),
V = cache_get(Tab, K, Cache),
kv_pmap_persist(Tab, SessionId, K, V)
end,
Dirty
@ -670,13 +697,110 @@ pmap_commit(
}.
-spec pmap_format(pmap(_K, _V)) -> map().
pmap_format(#pmap{cache = Cache}) ->
Cache.
pmap_format(#pmap{table = Table, cache = Cache}) ->
cache_format(Table, Cache).
-spec pmap_size(pmap(_K, _V)) -> non_neg_integer().
pmap_size(#pmap{cache = Cache}) ->
pmap_size(#pmap{table = Table, cache = Cache}) ->
cache_size(Table, Cache).
pmap_iter_after(After, #pmap{table = Table, cache = Cache}) ->
%% NOTE: Only valid for gbt-backed PMAPs.
gbt = cache_data_type(Table),
gbt_iter_after(After, Cache).
%%
cache_data_type(?stream_tab) -> gbt;
cache_data_type(_Table) -> map.
cache_from_list(?stream_tab, L) ->
gbt_from_list(L);
cache_from_list(_Table, L) ->
maps:from_list(L).
cache_get(?stream_tab, K, Cache) ->
gbt_get(K, Cache, undefined);
cache_get(_Table, K, Cache) ->
maps:get(K, Cache, undefined).
cache_put(?stream_tab, K, V, Cache) ->
gbt_put(K, V, Cache);
cache_put(_Table, K, V, Cache) ->
maps:put(K, V, Cache).
cache_remove(?stream_tab, K, Cache) ->
gbt_remove(K, Cache);
cache_remove(_Table, K, Cache) ->
maps:remove(K, Cache).
cache_fold(?stream_tab, Fun, Acc, Cache) ->
gbt_fold(Fun, Acc, Cache);
cache_fold(_Table, Fun, Acc, Cache) ->
maps:fold(Fun, Acc, Cache).
cache_format(?stream_tab, Cache) ->
gbt_format(Cache);
cache_format(_Table, Cache) ->
Cache.
cache_size(?stream_tab, Cache) ->
gbt_size(Cache);
cache_size(_Table, Cache) ->
maps:size(Cache).
%% PMAP Cache implementation backed by `gb_trees'.
%% Supports iteration starting from specific key.
gbt_from_list(L) ->
lists:foldl(
fun({K, V}, Acc) -> gb_trees:insert(K, V, Acc) end,
gb_trees:empty(),
L
).
gbt_get(K, Cache, undefined) ->
case gb_trees:lookup(K, Cache) of
none -> undefined;
{_, V} -> V
end.
gbt_put(K, V, Cache) ->
gb_trees:enter(K, V, Cache).
gbt_remove(K, Cache) ->
gb_trees:delete_any(K, Cache).
gbt_format(Cache) ->
gb_trees:to_list(Cache).
gbt_fold(Fun, Acc, Cache) ->
It = gb_trees:iterator(Cache),
gbt_fold_iter(Fun, Acc, It).
gbt_fold_iter(Fun, Acc, It0) ->
case gb_trees:next(It0) of
{K, V, It} ->
gbt_fold_iter(Fun, Fun(K, V, Acc), It);
_ ->
Acc
end.
gbt_size(Cache) ->
gb_trees:size(Cache).
gbt_iter_after(After, Cache) ->
It0 = gb_trees:iterator_from(After, Cache),
case gb_trees:next(It0) of
{After, _, It} ->
It;
_ ->
It0
end.
gbt_iter_next(It) ->
gb_trees:next(It).
%% Functions dealing with set tables:
kv_persist(Tab, SessionId, Val0) ->

96
apps/emqx/src/emqx_persistent_session_ds/emqx_persistent_session_ds_stream_scheduler.erl
View File

@ -16,7 +16,8 @@
-module(emqx_persistent_session_ds_stream_scheduler).
%% API:
-export([find_new_streams/1, find_replay_streams/1, is_fully_acked/2]).
-export([iter_next_streams/2, next_stream/1]).
-export([find_replay_streams/1, is_fully_acked/2]).
-export([renew_streams/1, on_unsubscribe/2]).
%% behavior callbacks:
@ -35,6 +36,29 @@
%% Type declarations
%%================================================================================
-type stream_key() :: emqx_persistent_session_ds_state:stream_key().
-type stream_state() :: emqx_persistent_session_ds:stream_state().
%% Restartable iterator with a filter and an iteration limit.
-record(iter, {
limit :: non_neg_integer(),
filter,
it,
it_cont
}).
-type iter(K, V, IterInner) :: #iter{
filter :: fun((K, V) -> boolean()),
it :: IterInner,
it_cont :: IterInner
}.
-type iter_stream() :: iter(
stream_key(),
stream_state(),
emqx_persistent_session_ds_state:iter(stream_key(), stream_state())
).
%%================================================================================
%% API functions
%%================================================================================
@ -70,9 +94,9 @@ find_replay_streams(S) ->
%%
%% This function is non-detereministic: it randomizes the order of
%% streams to ensure fair replay of different topics.
-spec find_new_streams(emqx_persistent_session_ds_state:t()) ->
[{emqx_persistent_session_ds_state:stream_key(), emqx_persistent_session_ds:stream_state()}].
find_new_streams(S) ->
-spec iter_next_streams(_LastVisited :: stream_key(), emqx_persistent_session_ds_state:t()) ->
iter_stream().
iter_next_streams(LastVisited, S) ->
%% FIXME: this function is currently very sensitive to the
%% consistency of the packet IDs on both broker and client side.
%%
@ -87,23 +111,44 @@ find_new_streams(S) ->
%% after timeout?)
Comm1 = emqx_persistent_session_ds_state:get_seqno(?committed(?QOS_1), S),
Comm2 = emqx_persistent_session_ds_state:get_seqno(?committed(?QOS_2), S),
shuffle(
emqx_persistent_session_ds_state:fold_streams(
fun
(_Key, #srs{it_end = end_of_stream}, Acc) ->
Acc;
(Key, Stream, Acc) ->
case is_fully_acked(Comm1, Comm2, Stream) andalso not Stream#srs.unsubscribed of
Filter = fun(_Key, Stream) -> is_fetchable(Comm1, Comm2, Stream) end,
#iter{
%% Limit the iteration to one round over all streams:
limit = emqx_persistent_session_ds_state:n_streams(S),
%% Filter out the streams not eligible for fetching:
filter = Filter,
%% Start the iteration right after the last visited stream:
it = emqx_persistent_session_ds_state:iter_streams(LastVisited, S),
%% Restart the iteration from the beginning:
it_cont = emqx_persistent_session_ds_state:iter_streams(beginning, S)
}.
-spec next_stream(iter_stream()) -> {stream_key(), stream_state(), iter_stream()} | none.
next_stream(#iter{limit = 0}) ->
none;
next_stream(ItStream0 = #iter{limit = N, filter = Filter, it = It0, it_cont = ItCont}) ->
case emqx_persistent_session_ds_state:iter_next(It0) of
{Key, Stream, It} ->
ItStream = ItStream0#iter{it = It, limit = N - 1},
case Filter(Key, Stream) of
true ->
[{Key, Stream} | Acc];
{Key, Stream, ItStream};
false ->
Acc
end
end,
[],
S
)
).
next_stream(ItStream)
end;
none when It0 =/= ItCont ->
%% Restart the iteration from the beginning:
ItStream = ItStream0#iter{it = ItCont},
next_stream(ItStream);
none ->
%% No point in restarting the iteration, `ItCont` is empty:
none
end.
is_fetchable(_Comm1, _Comm2, #srs{it_end = end_of_stream}) ->
false;
is_fetchable(Comm1, Comm2, #srs{unsubscribed = Unsubscribed} = Stream) ->
is_fully_acked(Comm1, Comm2, Stream) andalso not Unsubscribed.
%% @doc This function makes the session aware of the new streams.
%%
@ -410,19 +455,6 @@ is_fully_acked(_, _, #srs{
is_fully_acked(Comm1, Comm2, #srs{last_seqno_qos1 = S1, last_seqno_qos2 = S2}) ->
(Comm1 >= S1) andalso (Comm2 >= S2).
-spec shuffle([A]) -> [A].
shuffle(L0) ->
L1 = lists:map(
fun(A) ->
%% maybe topic/stream prioritization could be introduced here?
{rand:uniform(), A}
end,
L0
),
L2 = lists:sort(L1),
{_, L} = lists:unzip(L2),
L.
fold_proper_subscriptions(Fun, Acc, S) ->
emqx_persistent_session_ds_state:fold_subscriptions(
fun