[couchdb] branch prototype/fdb-layer updated: Fix doc counts for replicated deletions

[va...@apache.org]

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


The following commit(s) were added to refs/heads/prototype/fdb-layer by this push:
     new eed8fb1  Fix doc counts for replicated deletions
eed8fb1 is described below

commit eed8fb189dcbc2fe17eff798d16228ae036ce0ac
Author: Nick Vatamaniuc <va...@apache.org>
AuthorDate: Tue Sep 24 02:25:39 2019 -0400

    Fix doc counts for replicated deletions
    
    Do not decrement `doc_count` stat if document was previously missing, or if it
    was already deleted.
    
    Deleted documents could be brought in by replication. In that case, if there
    were more replicated documents than the current `doc_count`, the `doc_count`
    could even underflow the 64 bit unsigned integer range and end up somewhere in
    the vicinity of 2^64. The counter, of course, would still be incorrect even if
    it didn't underflow, the huge value would just make the issue more visible.
---
 src/fabric/src/fabric2_fdb.erl              | 12 ++++++++++--
 src/fabric/test/fabric2_doc_count_tests.erl | 26 ++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/fabric/src/fabric2_fdb.erl b/src/fabric/src/fabric2_fdb.erl
index ccfeb3c..5c58da4 100644
--- a/src/fabric/src/fabric2_fdb.erl
+++ b/src/fabric/src/fabric2_fdb.erl
@@ -556,7 +556,7 @@ write_doc(#{} = Db0, Doc, NewWinner0, OldWinner, ToUpdate, ToRemove) ->
         {not_found, #{deleted := false}} ->
             created;
         {not_found, #{deleted := true}} ->
-            deleted;
+            replicate_deleted;
         {#{deleted := true}, #{deleted := false}} ->
             recreated;
         {#{deleted := false}, #{deleted := false}} ->
@@ -564,10 +564,14 @@ write_doc(#{} = Db0, Doc, NewWinner0, OldWinner, ToUpdate, ToRemove) ->
         {#{deleted := false}, #{deleted := true}} ->
             deleted;
         {#{deleted := true}, #{deleted := true}} ->
-            deleted
+            ignore
     end,
 
     case UpdateStatus of
+        replicate_deleted ->
+            ok;
+        ignore ->
+            ok;
         deleted ->
             ADKey = erlfdb_tuple:pack({?DB_ALL_DOCS, DocId}, DbPrefix),
             ok = erlfdb:clear(Tx, ADKey);
@@ -614,6 +618,10 @@ write_doc(#{} = Db0, Doc, NewWinner0, OldWinner, ToUpdate, ToRemove) ->
             end,
             incr_stat(Db, <<"doc_count">>, 1),
             incr_stat(Db, <<"doc_del_count">>, -1);
+        replicate_deleted ->
+            incr_stat(Db, <<"doc_del_count">>, 1);
+        ignore ->
+            ok;
         deleted ->
             if not IsDDoc -> ok; true ->
                 incr_stat(Db, <<"doc_design_count">>, -1)
diff --git a/src/fabric/test/fabric2_doc_count_tests.erl b/src/fabric/test/fabric2_doc_count_tests.erl
index 37d0840..743ae76 100644
--- a/src/fabric/test/fabric2_doc_count_tests.erl
+++ b/src/fabric/test/fabric2_doc_count_tests.erl
@@ -30,6 +30,7 @@ doc_count_test_() ->
             fun cleanup/1,
             {with, [
                 fun normal_docs/1,
+                fun replicated_docs/1,
                 fun design_docs/1,
                 fun local_docs/1
             ]}
@@ -109,6 +110,31 @@ normal_docs({Db, _}) ->
         ).
 
 
+replicated_docs({Db, _}) ->
+    {DocCount, DelDocCount, DDocCount, LDocCount} = get_doc_counts(Db),
+
+    Opts = [replicated_changes],
+    {R1, R2, R3} = {<<"r1">>, <<"r2">>, <<"r3">>},
+
+    % First case is a simple replicated update
+    Doc1 = #doc{id = <<"rd1">>, revs = {1, [R1]}},
+    {ok, {1, R1}} = fabric2_db:update_doc(Db, Doc1, Opts),
+    check_doc_counts(Db, DocCount + 1, DelDocCount, DDocCount, LDocCount),
+
+    % Here a deleted document is replicated into the db. Doc count should not
+    % change, only deleted doc count.
+    Doc2 = #doc{id = <<"rd2">>, revs = {1, [R2]}, deleted = true},
+    {ok, {1, R2}} = fabric2_db:update_doc(Db, Doc2, Opts),
+    check_doc_counts(Db, DocCount + 1, DelDocCount + 1, DDocCount, LDocCount),
+
+    % Here we extended the deleted document's rev path but keep it deleted.
+    % Deleted doc count doesn't bumped since the document was already counted
+    % as deleted
+    Doc3 = #doc{id = <<"rd2">>, revs = {2, [R3, R2]}, deleted = true},
+    {ok, {2, R3}} = fabric2_db:update_doc(Db, Doc3, Opts),
+    check_doc_counts(Db, DocCount + 1, DelDocCount + 1 , DDocCount, LDocCount).
+
+
 design_docs({Db, _}) ->
     {DocCount, DelDocCount, DDocCount, LDocCount} = get_doc_counts(Db),