All tests pass, but checkpointing does not truncate history

prototype/tango-prototype/src/tango.erl

@@ -31,7 +31,8 @@
          scan_backward/5,
          pad_bin/2,
          append_page/3,
-         back_ps2last_lpn/1]).
+         back_ps2last_lpn/1,
+         append_lpns/2]).
 
 -define(MAGIC_NUMBER_V1, 16#88990011).
 
@@ -210,3 +211,9 @@ back_ps2last_lpn([]) ->
     0;
 back_ps2last_lpn([H|_]) ->
     H.
+
+append_lpns([], BPs) ->
+    BPs;
+append_lpns(LPNs, BPs) ->
+    lists:reverse(LPNs) ++ BPs.
+

prototype/tango-prototype/src/tango_dt.erl

@@ -75,7 +75,7 @@ checkpoint(Pid) ->
 init([PageSize, SequencerPid, Proj, CallbackMod, StreamNum]) ->
     LastLPN = find_last_lpn(SequencerPid, StreamNum),
     {LPNs, Pages} = fetch_unread_pages(Proj, LastLPN, 0, StreamNum),
-    BackPs = lists:reverse(LPNs),
+    BackPs = tango:append_lpns(LPNs, []),
     LastFetchLPN = tango:back_ps2last_lpn(BackPs),
     I_State = play_log_pages(Pages, CallbackMod:fresh(), CallbackMod, false),
     {ok, #state{page_size=PageSize,
@@ -144,7 +144,6 @@ find_last_lpn(SequencerPid, StreamNum) ->
 
 fetch_unread_pages(Proj, LastLPN, StopAtLPN, StreamNum)
   when LastLPN >= StopAtLPN ->
-    %% ?D({fetch_unread_pages, LastLPN, StopAtLPN}),
     LPNandPages = tango:scan_backward(Proj, StreamNum, LastLPN,
                                       StopAtLPN, true),
     {_LPNs, _Pages} = lists:unzip(LPNandPages).
@@ -162,11 +161,8 @@ roll_log_forward(#state{seq=SequencerPid, proj=Proj, all_back_ps=BackPs,
                         last_fetch_lpn=StopAtLPN} = State) ->
     LastLPN = find_last_lpn(SequencerPid, StreamNum),
     {LPNs, Pages} = fetch_unread_pages(Proj, LastLPN, StopAtLPN, StreamNum),
-    NewBPs = append_lpns(LPNs, BackPs),
-    play_log_pages(Pages, true, State#state{all_back_ps=NewBPs}).
-
-append_lpns([], BPs) ->
-    BPs;
-append_lpns(LPNs, BPs) ->
-    lists:reverse(LPNs) ++ BPs.
-
+    NewBackPs = tango:append_lpns(LPNs, BackPs),
+    LastFetchLPN = tango:back_ps2last_lpn(NewBackPs),
+    play_log_pages(Pages, true,
+                   State#state{all_back_ps=NewBackPs,
+                               last_fetch_lpn=LastFetchLPN}).

prototype/tango-prototype/src/tango_oid.erl

@@ -70,7 +70,7 @@ get(Pid, Key) ->
 init([PageSize, SequencerPid, Proj]) ->
     LastLPN = find_last_lpn(SequencerPid, ?OID_STREAM_NUMBER),
     {LPNs, Pages} = fetch_unread_pages(Proj, LastLPN, 0, ?OID_STREAM_NUMBER),
-    BackPs = lists:reverse(LPNs),
+    BackPs = tango:append_lpns(LPNs, []),
     LastFetchLPN = tango:back_ps2last_lpn(BackPs),
     I_State = play_log_pages(Pages, fresh(), ?MODULE, false),
     {ok, #state{page_size=PageSize,
@@ -127,7 +127,6 @@ find_last_lpn(SequencerPid, StreamNum) ->
 
 fetch_unread_pages(Proj, LastLPN, StopAtLPN, StreamNum)
   when LastLPN >= StopAtLPN ->
-    %% ?D({fetch_unread_pages, LastLPN, StopAtLPN}),
     LPNandPages = tango:scan_backward(Proj, StreamNum, LastLPN,
                                       StopAtLPN, true),
     {_LPNs, _Pages} = lists:unzip(LPNandPages).
@@ -144,14 +143,9 @@ roll_log_forward(#state{seq=SequencerPid, proj=Proj, all_back_ps=BackPs,
                         last_fetch_lpn=StopAtLPN} = State) ->
     LastLPN = find_last_lpn(SequencerPid, ?OID_STREAM_NUMBER),
     {LPNs, Pages} = fetch_unread_pages(Proj, LastLPN, StopAtLPN, ?OID_STREAM_NUMBER),
-    NewBPs = append_lpns(LPNs, BackPs),
+    NewBPs = tango:append_lpns(LPNs, BackPs),
     play_log_pages(Pages, true, State#state{all_back_ps=NewBPs}).
 
-append_lpns([], BPs) ->
-    BPs;
-append_lpns(LPNs, BPs) ->
-    lists:reverse(LPNs) ++ BPs.
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 -record(oid_map, {

prototype/tango-prototype/test/tango_test.erl

@@ -260,7 +260,8 @@ tango_dt_queue_int(PageSize, Seq, Proj) ->
 
     {ok, true} = MOD:is_empty(Q1),
     {ok, 0} = MOD:length(Q1),
-    Num1 = 15,
+
+    Num1 = 4,
     Seq1 = lists:seq(1, Num1),
     RevSeq1 = lists:reverse(Seq1),
     [ok = MOD:in(Q1, X) || X <- Seq1],