feat(ds_buffer): Add `ls' function to list all local buffers

apps/emqx_durable_storage/src/emqx_ds_buffer.erl

@@ -22,6 +22,7 @@
 
 %% API:
 -export([start_link/4, store_batch/3, shard_of_message/3]).
+-export([ls/0]).
 
 %% behavior callbacks:
 -export([init/1, format_status/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
@@ -63,6 +64,11 @@
 %% API functions
 %%================================================================================
 
+-spec ls() -> [{emqx_ds:db(), _Shard}].
+ls() ->
+    MS = {{n, l, {?MODULE, '$1', '$2'}}, [], ['$1', '$2']},
+    gproc:select({local, names}, [MS]).
+
 -spec start_link(module(), _CallbackOptions, emqx_ds:db(), _ShardId) ->
     {ok, pid()}.
 start_link(CallbackModule, CallbackOptions, DB, Shard) ->
@@ -267,12 +273,12 @@ do_flush(
     {CallbackS, Result} = CBM:flush_buffer(DB, Shard, Messages, CallbackS0),
     S = S0#s{callback_state = CallbackS},
     T1 = erlang:monotonic_time(microsecond),
-    emqx_ds_builtin_metrics:observe_egress_flush_time(Metrics, T1 - T0),
+    emqx_ds_builtin_metrics:observe_buffer_flush_time(Metrics, T1 - T0),
     case Result of
         ok ->
-            emqx_ds_builtin_metrics:inc_egress_batches(Metrics),
-            emqx_ds_builtin_metrics:inc_egress_messages(Metrics, S#s.n),
-            emqx_ds_builtin_metrics:inc_egress_bytes(Metrics, S#s.n_bytes),
+            emqx_ds_builtin_metrics:inc_buffer_batches(Metrics),
+            emqx_ds_builtin_metrics:inc_buffer_messages(Metrics, S#s.n),
+            emqx_ds_builtin_metrics:inc_buffer_bytes(Metrics, S#s.n_bytes),
             ?tp(
                 emqx_ds_buffer_flush,
                 #{db => DB, shard => Shard, batch => Messages}
@@ -298,7 +304,7 @@ do_flush(
                 #{db => DB, shard => Shard, reason => Err}
             ),
             %% Retry sending the batch:
-            emqx_ds_builtin_metrics:inc_egress_batches_retry(Metrics),
+            emqx_ds_builtin_metrics:inc_buffer_batches_retry(Metrics),
             erlang:garbage_collect(),
             %% We block the gen_server until the next retry.
             BlockTime = ?COOLDOWN_MIN + rand:uniform(?COOLDOWN_MAX - ?COOLDOWN_MIN),
@@ -310,7 +316,7 @@ do_flush(
                 emqx_ds_buffer_flush_failed,
                 #{db => DB, shard => Shard, error => Err}
             ),
-            emqx_ds_builtin_metrics:inc_egress_batches_failed(Metrics),
+            emqx_ds_builtin_metrics:inc_buffer_batches_failed(Metrics),
             Reply =
                 case Err of
                     {error, _, _} -> Err;

apps/emqx_durable_storage/src/emqx_ds_builtin_metrics.erl

@@ -22,13 +22,13 @@
 -export([prometheus_meta/0, prometheus_collect/1]).
 
 -export([
-    inc_egress_batches/1,
-    inc_egress_batches_retry/1,
-    inc_egress_batches_failed/1,
-    inc_egress_messages/2,
-    inc_egress_bytes/2,
+    inc_buffer_batches/1,
+    inc_buffer_batches_retry/1,
+    inc_buffer_batches_failed/1,
+    inc_buffer_messages/2,
+    inc_buffer_bytes/2,
 
-    observe_egress_flush_time/2,
+    observe_buffer_flush_time/2,
 
     observe_store_batch_time/2,
 
@@ -106,36 +106,36 @@ init_for_shard(ShardId) ->
     emqx_metrics_worker:create_metrics(?WORKER, ShardId, ?SHARD_METRICS, []).
 
 %% @doc Increase the number of successfully flushed batches
--spec inc_egress_batches(shard_metrics_id()) -> ok.
-inc_egress_batches(Id) ->
+-spec inc_buffer_batches(shard_metrics_id()) -> ok.
+inc_buffer_batches(Id) ->
     catch emqx_metrics_worker:inc(?WORKER, Id, ?DS_BUFFER_BATCHES).
 
-%% @doc Increase the number of time the egress worker had to retry
+%% @doc Increase the number of time the buffer worker had to retry
 %% flushing the batch
--spec inc_egress_batches_retry(shard_metrics_id()) -> ok.
-inc_egress_batches_retry(Id) ->
+-spec inc_buffer_batches_retry(shard_metrics_id()) -> ok.
+inc_buffer_batches_retry(Id) ->
     catch emqx_metrics_worker:inc(?WORKER, Id, ?DS_BUFFER_BATCHES_RETRY).
 
-%% @doc Increase the number of time the egress worker encountered an
+%% @doc Increase the number of time the buffer worker encountered an
 %% unrecoverable error while trying to flush the batch
--spec inc_egress_batches_failed(shard_metrics_id()) -> ok.
-inc_egress_batches_failed(Id) ->
+-spec inc_buffer_batches_failed(shard_metrics_id()) -> ok.
+inc_buffer_batches_failed(Id) ->
     catch emqx_metrics_worker:inc(?WORKER, Id, ?DS_BUFFER_BATCHES_FAILED).
 
 %% @doc Increase the number of messages successfully saved to the shard
--spec inc_egress_messages(shard_metrics_id(), non_neg_integer()) -> ok.
-inc_egress_messages(Id, NMessages) ->
+-spec inc_buffer_messages(shard_metrics_id(), non_neg_integer()) -> ok.
+inc_buffer_messages(Id, NMessages) ->
     catch emqx_metrics_worker:inc(?WORKER, Id, ?DS_BUFFER_MESSAGES, NMessages).
 
 %% @doc Increase the number of messages successfully saved to the shard
--spec inc_egress_bytes(shard_metrics_id(), non_neg_integer()) -> ok.
-inc_egress_bytes(Id, NMessages) ->
+-spec inc_buffer_bytes(shard_metrics_id(), non_neg_integer()) -> ok.
+inc_buffer_bytes(Id, NMessages) ->
     catch emqx_metrics_worker:inc(?WORKER, Id, ?DS_BUFFER_BYTES, NMessages).
 
-%% @doc Add a sample of elapsed time spent flushing the egress to the
+%% @doc Add a sample of elapsed time spent flushing the buffer to the
 %% Raft log (in microseconds)
--spec observe_egress_flush_time(shard_metrics_id(), non_neg_integer()) -> ok.
-observe_egress_flush_time(Id, FlushTime) ->
+-spec observe_buffer_flush_time(shard_metrics_id(), non_neg_integer()) -> ok.
+observe_buffer_flush_time(Id, FlushTime) ->
     catch emqx_metrics_worker:observe(?WORKER, Id, ?DS_BUFFER_FLUSH_TIME, FlushTime).
 
 -spec observe_store_batch_time(emqx_ds_storage_layer:shard_id(), non_neg_integer()) -> ok.
@@ -221,13 +221,13 @@ prometheus_per_db(NodeOrAggr, DB, Acc0) ->
 
 %% This function returns the data in the following format:
 %% ```
-%% #{emqx_ds_egress_batches =>
+%% #{emqx_ds_buffer_batches =>
 %%       [{[{db,messages},{shard,<<"1">>}],99408},
 %%        {[{db,messages},{shard,<<"0">>}],99409}],
-%%   emqx_ds_egress_batches_retry =>
+%%   emqx_ds_buffer_batches_retry =>
 %%       [{[{db,messages},{shard,<<"1">>}],0},
 %%        {[{db,messages},{shard,<<"0">>}],0}],
-%%   emqx_ds_egress_messages =>
+%%   emqx_ds_buffer_messages =>
 %%        ...
 %%  }
 %% '''