[couchdb] 02/02: Clean up old expiry key on update insert

[ja...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

jaydoane pushed a commit to branch prototype/fdb-layer
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit 4098c12abeffdf89988663ec9d17544f6509256f
Author: Jay Doane <ja...@apache.org>
AuthorDate: Wed Apr 15 22:01:33 2020 -0700

    Clean up old expiry key on update insert
    
    When an existing key is inserted with different timestamps, the primary
    key is the same but the primary value is different from the existing one.
    Currently, this results in a new expiry key being inserted, but the old
    one is not deleted and lingers until it is removed by the inexorable
    advance of time via the `remove_expired` server messages.
    
    This checks whether there's already primary key for the inserted key,
    and if so, cleans up the existing expiry key before proceeding with the
    insert.
---
 .../src/couch_expiring_cache_fdb.erl               | 27 ++++++++++++++++++++++
 .../test/couch_expiring_cache_tests.erl            | 19 +++++++++++++--
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/src/couch_expiring_cache/src/couch_expiring_cache_fdb.erl b/src/couch_expiring_cache/src/couch_expiring_cache_fdb.erl
index dc33766..7c4ad8f 100644
--- a/src/couch_expiring_cache/src/couch_expiring_cache_fdb.erl
+++ b/src/couch_expiring_cache/src/couch_expiring_cache_fdb.erl
@@ -13,6 +13,7 @@
 -module(couch_expiring_cache_fdb).
 
 -export([
+    get_range_to/3,
     insert/6,
     lookup/3,
     clear_all/1,
@@ -40,6 +41,16 @@
 insert(#{jtx := true} = JTx, Name, Key, Val, StaleTS, ExpiresTS) ->
     #{tx := Tx, layer_prefix := LayerPrefix} = couch_jobs_fdb:get_jtx(JTx),
     PK = primary_key(Name, Key, LayerPrefix),
+    case get_val(Tx, PK) of
+        not_found ->
+            ok;
+        {_OldVal, _OldStaleTS, OldExpiresTS} ->
+            % Clean up current expiry key for this primary key. No
+            % need to clean up the existing primary key since it will
+            % be overwritten below.
+            OldXK = expiry_key(OldExpiresTS, Name, Key, LayerPrefix),
+            ok = erlfdb:clear(Tx, OldXK)
+    end,
     PV = erlfdb_tuple:pack({Val, StaleTS, ExpiresTS}),
     ok = erlfdb:set(Tx, PK, PV),
     XK = expiry_key(ExpiresTS, Name, Key, LayerPrefix),
@@ -87,6 +98,22 @@ clear_range_to(Name, EndTS, Limit) when Limit > 0 ->
         end, 0).
 
 
+-spec get_range_to(Name :: binary(), EndTS :: ?TIME_UNIT,
+    Limit :: non_neg_integer()) ->
+        [{Key :: binary(), Val :: binary()}].
+get_range_to(Name, EndTS, Limit) when Limit > 0 ->
+    fold_range(Name, EndTS, Limit,
+        fun(Tx, PK, _XK, Key, _ExpiresTS, Acc) ->
+            case get_val(Tx, PK) of
+                not_found ->
+                    couch_log:error("~p:entry missing Key: ~p", [?MODULE, Key]),
+                    Acc;
+                Val ->
+                    [{Key, Val} | Acc]
+            end
+        end, []).
+
+
 %% Private
 
 
diff --git a/src/couch_expiring_cache/test/couch_expiring_cache_tests.erl b/src/couch_expiring_cache/test/couch_expiring_cache_tests.erl
index aeb1df6..2e06fcc 100644
--- a/src/couch_expiring_cache/test/couch_expiring_cache_tests.erl
+++ b/src/couch_expiring_cache/test/couch_expiring_cache_tests.erl
@@ -66,7 +66,7 @@ teardown(#{pid := Pid}) ->
 
 
 simple_lifecycle(_) ->
-    ?_test(begin
+    {timeout, 10, ?_test(begin
         Now = erlang:system_time(?TIME_UNIT),
         StaleTS = Now + 100,
         ExpiresTS = Now + 200,
@@ -76,14 +76,29 @@ simple_lifecycle(_) ->
 
         ?assertEqual(ok, couch_expiring_cache_fdb:clear_all(Name)),
         ?assertEqual(not_found, couch_expiring_cache:lookup(Name, Key)),
+        ?assertEqual([], entries(Name)),
         ?assertEqual(ok,
             couch_expiring_cache:insert(Name, Key, Val, StaleTS, ExpiresTS)),
         ?assertEqual({fresh, Val}, couch_expiring_cache:lookup(Name, Key)),
         ok = wait_lookup(Name, Key, {stale, Val}),
+
+        % Refresh the existing key with updated timestamps
+        ?assertEqual(ok,
+            couch_expiring_cache:insert(Name, Key, Val,
+                StaleTS + 100, ExpiresTS + 100)),
+        ?assertEqual({fresh, Val}, couch_expiring_cache:lookup(Name, Key)),
+        ?assertEqual(1, length(entries(Name))),
+        ok = wait_lookup(Name, Key, {stale, Val}),
         ok = wait_lookup(Name, Key, expired),
         ok = wait_lookup(Name, Key, not_found),
+        ?assertEqual([], entries(Name)),
         ?assertEqual(not_found, couch_expiring_cache:lookup(Name, Key))
-    end).
+    end)}.
+
+
+entries(Name) ->
+    FarFuture = erlang:system_time(?TIME_UNIT) * 2,
+    couch_expiring_cache_fdb:get_range_to(Name, FarFuture, _Limit=100).
 
 
 wait_lookup(Name, Key, Expect) ->