refactor(sessds): rename marker → committed offset

For better clarity.

apps/emqx/src/emqx_persistent_message_ds_replayer.erl

@@ -21,7 +21,7 @@
 %% API:
 -export([new/0, open/1, next_packet_id/1, n_inflight/1]).
 
--export([poll/4, replay/2, commit_offset/4, commit_marker/4]).
+-export([poll/4, replay/2, commit_offset/4]).
 
 -export([seqno_to_packet_id/1, packet_id_to_seqno/2]).
 
@@ -55,11 +55,11 @@
 -type seqno() :: non_neg_integer().
 
 -type track() :: ack | comp.
--type marker() :: rec.
+-type commit_type() :: rec.
 
 -record(inflight, {
     next_seqno = 1 :: seqno(),
-    commits = #{ack => 1, comp => 1, rec => 1} :: #{track() | marker() => seqno()},
+    commits = #{ack => 1, comp => 1, rec => 1} :: #{track() | commit_type() => seqno()},
     %% Ranges are sorted in ascending order of their sequence numbers.
     offset_ranges = [] :: [ds_pubrange()]
 }).
@@ -82,7 +82,7 @@ new() ->
 -spec open(emqx_persistent_session_ds:id()) -> inflight().
 open(SessionId) ->
     {Ranges, RecUntil} = ro_transaction(
-        fun() -> {get_ranges(SessionId), get_marker(SessionId, rec)} end
+        fun() -> {get_ranges(SessionId), get_committed_offset(SessionId, rec)} end
     ),
     {Commits, NextSeqno} = compute_inflight_range(Ranges),
     #inflight{
@@ -128,14 +128,16 @@ replay(ReplyFun, Inflight0 = #inflight{offset_ranges = Ranges0}) ->
     Inflight = Inflight0#inflight{offset_ranges = Ranges},
     {Replies, Inflight}.
 
--spec commit_offset(emqx_persistent_session_ds:id(), track(), emqx_types:packet_id(), inflight()) ->
+-spec commit_offset(emqx_persistent_session_ds:id(), Offset, emqx_types:packet_id(), inflight()) ->
-    {_IsValidOffset :: boolean(), inflight()}.
+    {_IsValidOffset :: boolean(), inflight()}
+when
+    Offset :: track() | commit_type().
 commit_offset(
     SessionId,
     Track,
     PacketId,
     Inflight0 = #inflight{commits = Commits}
-) ->
+) when Track == ack orelse Track == comp ->
     case validate_commit(Track, PacketId, Inflight0) of
         CommitUntil when is_integer(CommitUntil) ->
             %% TODO
@@ -148,20 +150,17 @@ commit_offset(
             {true, Inflight};
         false ->
             {false, Inflight0}
-    end.
+    end;
-
+commit_offset(
--spec commit_marker(emqx_persistent_session_ds:id(), marker(), emqx_types:packet_id(), inflight()) ->
-    {_IsValidMarker :: boolean(), inflight()}.
-commit_marker(
     SessionId,
-    Marker = rec,
+    CommitType = rec,
     PacketId,
     Inflight0 = #inflight{commits = Commits}
 ) ->
-    case validate_commit(Marker, PacketId, Inflight0) of
+    case validate_commit(CommitType, PacketId, Inflight0) of
         CommitUntil when is_integer(CommitUntil) ->
-            update_marker(SessionId, Marker, CommitUntil),
+            update_committed_offset(SessionId, CommitType, CommitUntil),
-            Inflight = Inflight0#inflight{commits = Commits#{Marker := CommitUntil}},
+            Inflight = Inflight0#inflight{commits = Commits#{CommitType := CommitUntil}},
             {true, Inflight};
         false ->
             {false, Inflight0}
@@ -187,7 +186,7 @@ poll(ReplyFun, SessionId, Inflight0, WindowSize) when WindowSize > 0, WindowSize
 
 %% Which seqno this track is committed until.
 %% "Until" means this is first seqno that is _not yet committed_ for this track.
--spec committed_until(track() | marker(), inflight()) -> seqno().
+-spec committed_until(track() | commit_type(), inflight()) -> seqno().
 committed_until(Track, #inflight{commits = Commits}) ->
     maps:get(Track, Commits).
 
@@ -491,18 +490,20 @@ get_last_iterator(DSStream = #ds_stream{ref = StreamRef}, Ranges) ->
 get_streams(SessionId) ->
     mnesia:dirty_read(?SESSION_STREAM_TAB, SessionId).
 
--spec get_marker(emqx_persistent_session_ds:id(), _Name) -> seqno().
+-spec get_committed_offset(emqx_persistent_session_ds:id(), _Name) -> seqno().
-get_marker(SessionId, Name) ->
+get_committed_offset(SessionId, Name) ->
-    case mnesia:read(?SESSION_MARKER_TAB, {SessionId, Name}) of
+    case mnesia:read(?SESSION_COMMITTED_OFFSET_TAB, {SessionId, Name}) of
         [] ->
             1;
-        [#ds_marker{until = Seqno}] ->
+        [#ds_committed_offset{until = Seqno}] ->
             Seqno
     end.
 
--spec update_marker(emqx_persistent_session_ds:id(), _Name, seqno()) -> ok.
+-spec update_committed_offset(emqx_persistent_session_ds:id(), _Name, seqno()) -> ok.
-update_marker(SessionId, Name, Until) ->
+update_committed_offset(SessionId, Name, Until) ->
-    mria:dirty_write(?SESSION_MARKER_TAB, #ds_marker{id = {SessionId, Name}, until = Until}).
+    mria:dirty_write(?SESSION_COMMITTED_OFFSET_TAB, #ds_committed_offset{
+        id = {SessionId, Name}, until = Until
+    }).
 
 next_seqno(Seqno) ->
     NextSeqno = Seqno + 1,

apps/emqx/src/emqx_persistent_session_ds.erl

@@ -239,7 +239,7 @@ print_session(ClientId) ->
                         session => Session,
                         streams => mnesia:read(?SESSION_STREAM_TAB, ClientId),
                         pubranges => session_read_pubranges(ClientId),
-                        markers => session_read_markers(ClientId),
+                        offsets => session_read_offsets(ClientId),
                         subscriptions => session_read_subscriptions(ClientId)
                     };
                 [] ->
@@ -338,7 +338,7 @@ puback(_ClientInfo, PacketId, Session = #{id := Id, inflight := Inflight0}) ->
     {ok, emqx_types:message(), session()}
     | {error, emqx_types:reason_code()}.
 pubrec(PacketId, Session = #{id := Id, inflight := Inflight0}) ->
-    case emqx_persistent_message_ds_replayer:commit_marker(Id, rec, PacketId, Inflight0) of
+    case emqx_persistent_message_ds_replayer:commit_offset(Id, rec, PacketId, Inflight0) of
         {true, Inflight} ->
             %% TODO
             Msg = emqx_message:make(Id, <<>>, <<>>),
@@ -552,13 +552,13 @@ create_tables() ->
         ]
     ),
     ok = mria:create_table(
-        ?SESSION_MARKER_TAB,
+        ?SESSION_COMMITTED_OFFSET_TAB,
         [
             {rlog_shard, ?DS_MRIA_SHARD},
             {type, set},
             {storage, storage()},
-            {record_name, ds_marker},
+            {record_name, ds_committed_offset},
-            {attributes, record_info(fields, ds_marker)}
+            {attributes, record_info(fields, ds_committed_offset)}
         ]
     ),
     ok = mria:wait_for_tables([
@@ -566,7 +566,7 @@ create_tables() ->
         ?SESSION_SUBSCRIPTIONS_TAB,
         ?SESSION_STREAM_TAB,
         ?SESSION_PUBRANGE_TAB,
-        ?SESSION_MARKER_TAB
+        ?SESSION_COMMITTED_OFFSET_TAB
     ]),
     ok.
 
@@ -633,7 +633,7 @@ session_drop(DSSessionId) ->
     transaction(fun() ->
         ok = session_drop_subscriptions(DSSessionId),
         ok = session_drop_pubranges(DSSessionId),
-        ok = session_drop_markers(DSSessionId),
+        ok = session_drop_offsets(DSSessionId),
         ok = session_drop_streams(DSSessionId),
         ok = mnesia:delete(?SESSION_TAB, DSSessionId, write)
     end).
@@ -725,16 +725,16 @@ session_read_pubranges(DSSessionId, LockKind) ->
     ),
     mnesia:select(?SESSION_PUBRANGE_TAB, MS, LockKind).
 
-session_read_markers(DSSessionID) ->
+session_read_offsets(DSSessionID) ->
-    session_read_markers(DSSessionID, read).
+    session_read_offsets(DSSessionID, read).
 
-session_read_markers(DSSessionId, LockKind) ->
+session_read_offsets(DSSessionId, LockKind) ->
     MS = ets:fun2ms(
-        fun(#ds_marker{id = {Sess, Name}}) when Sess =:= DSSessionId ->
+        fun(#ds_committed_offset{id = {Sess, Type}}) when Sess =:= DSSessionId ->
-            {DSSessionId, Name}
+            {DSSessionId, Type}
         end
     ),
-    mnesia:select(?SESSION_MARKER_TAB, MS, LockKind).
+    mnesia:select(?SESSION_COMMITTED_OFFSET_TAB, MS, LockKind).
 
 -spec new_subscription_id(id(), topic_filter()) -> {subscription_id(), integer()}.
 new_subscription_id(DSSessionId, TopicFilter) ->
@@ -846,14 +846,14 @@ session_drop_pubranges(DSSessionId) ->
     ).
 
 %% must be called inside a transaction
--spec session_drop_markers(id()) -> ok.
+-spec session_drop_offsets(id()) -> ok.
-session_drop_markers(DSSessionId) ->
+session_drop_offsets(DSSessionId) ->
-    MarkerIds = session_read_markers(DSSessionId, write),
+    OffsetIds = session_read_offsets(DSSessionId, write),
     lists:foreach(
-        fun(MarkerId) ->
+        fun(OffsetId) ->
-            mnesia:delete(?SESSION_MARKER_TAB, MarkerId, write)
+            mnesia:delete(?SESSION_COMMITTED_OFFSET_TAB, OffsetId, write)
         end,
-        MarkerIds
+        OffsetIds
     ).
 
 %%--------------------------------------------------------------------------------

apps/emqx/src/emqx_persistent_session_ds.hrl

@@ -22,7 +22,7 @@
 -define(SESSION_SUBSCRIPTIONS_TAB, emqx_ds_session_subscriptions).
 -define(SESSION_STREAM_TAB, emqx_ds_stream_tab).
 -define(SESSION_PUBRANGE_TAB, emqx_ds_pubrange_tab).
--define(SESSION_MARKER_TAB, emqx_ds_marker_tab).
+-define(SESSION_COMMITTED_OFFSET_TAB, emqx_ds_committed_offset_tab).
 -define(DS_MRIA_SHARD, emqx_ds_session_shard).
 
 -define(T_INFLIGHT, 1).
@@ -76,12 +76,12 @@
 }).
 -type ds_pubrange() :: #ds_pubrange{}.
 
--record(ds_marker, {
+-record(ds_committed_offset, {
     id :: {
         %% What session this marker belongs to.
         _Session :: emqx_persistent_session_ds:id(),
         %% Marker name.
-        _MarkerName
+        _CommitType
     },
     %% Where this marker is pointing to: the first seqno that is not marked.
     until :: emqx_persistent_message_ds_replayer:seqno()