From bc5283223a1594928dc6e13854a0e0132019e5ec Mon Sep 17 00:00:00 2001
From: "Paul J. Davis" <paul.joseph.davis@gmail.com>
Date: Tue, 3 Dec 2019 10:24:36 -0600
Subject: Track a database level view size rollup

This way we can expose the total view size for a database in the dbinfo
JSON blob.
---
 src/couch_views/src/couch_views_fdb.erl | 17 ++++++++++++++--
 src/fabric/src/fabric2_fdb.erl          | 36 ++++++++++++++++-----------------
 2 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/src/couch_views/src/couch_views_fdb.erl b/src/couch_views/src/couch_views_fdb.erl
index 98cff46b2..5edaa3a5f 100644
--- a/src/couch_views/src/couch_views_fdb.erl
+++ b/src/couch_views/src/couch_views_fdb.erl
@@ -272,8 +272,16 @@ update_kv_size(TxDb, Sig, ViewId, Increment) ->
         tx := Tx,
         db_prefix := DbPrefix
     } = TxDb,
-    Key = kv_size_key(DbPrefix, Sig, ViewId),
-    erlfdb:add(Tx, Key, Increment).
+
+    % Track a view specific size for calls to
+    % GET /dbname/_design/doc/_info`
+    IdxKey = kv_size_key(DbPrefix, Sig, ViewId),
+    erlfdb:add(Tx, IdxKey, Increment),
+
+    % Track a database level rollup for calls to
+    % GET /dbname
+    DbKey = db_kv_size_key(DbPrefix),
+    erlfdb:add(Tx, DbKey, Increment).
 
 
 seq_key(DbPrefix, Sig) ->
@@ -291,6 +299,11 @@ kv_size_key(DbPrefix, Sig, ViewId) ->
     erlfdb_tuple:pack(Key, DbPrefix).
 
 
+db_kv_size_key(DbPrefix) ->
+    Key = {?DB_STATS, <<"sizes">>, <<"views">>},
+    erlfdb_tuple:pack(Key, DbPrefix).
+
+
 id_idx_key(DbPrefix, Sig, DocId, ViewId) ->
     Key = {?DB_VIEWS, Sig, ?VIEW_ID_RANGE, DocId, ViewId},
     erlfdb_tuple:pack(Key, DbPrefix).
diff --git a/src/fabric/src/fabric2_fdb.erl b/src/fabric/src/fabric2_fdb.erl
index 6abe1f6de..8bfbb749a 100644
--- a/src/fabric/src/fabric2_fdb.erl
+++ b/src/fabric/src/fabric2_fdb.erl
@@ -174,11 +174,16 @@ create(#{} = Db0, Options) ->
         {?DB_STATS, <<"doc_del_count">>, ?uint2bin(0)},
         {?DB_STATS, <<"doc_design_count">>, ?uint2bin(0)},
         {?DB_STATS, <<"doc_local_count">>, ?uint2bin(0)},
-        {?DB_STATS, <<"size">>, ?uint2bin(2)}
+        {?DB_STATS, <<"sizes">>, <<"external">>, ?uint2bin(2)},
+        {?DB_STATS, <<"sizes">>, <<"views">>, ?uint2bin(0)}
     ],
-    lists:foreach(fun({P, K, V}) ->
-        Key = erlfdb_tuple:pack({P, K}, DbPrefix),
-        erlfdb:set(Tx, Key, V)
+    lists:foreach(fun
+        ({P, K, V}) ->
+            Key = erlfdb_tuple:pack({P, K}, DbPrefix),
+            erlfdb:set(Tx, Key, V);
+        ({P, S, K, V}) ->
+            Key = erlfdb_tuple:pack({P, S, K}, DbPrefix),
+            erlfdb:set(Tx, Key, V)
     end, Defaults),
 
     UserCtx = fabric2_util:get_value(user_ctx, Options, #user_ctx{}),
@@ -348,26 +353,21 @@ get_info(#{} = Db) ->
     end,
     CProp = {update_seq, RawSeq},
 
-    MProps = lists:flatmap(fun({K, V}) ->
+    MProps = lists:foldl(fun({K, V}, Acc) ->
         case erlfdb_tuple:unpack(K, DbPrefix) of
             {?DB_STATS, <<"doc_count">>} ->
-                [{doc_count, ?bin2uint(V)}];
+                [{doc_count, ?bin2uint(V)} | Acc];
             {?DB_STATS, <<"doc_del_count">>} ->
-                [{doc_del_count, ?bin2uint(V)}];
-            {?DB_STATS, <<"size">>} ->
+                [{doc_del_count, ?bin2uint(V)} | Acc];
+            {?DB_STATS, <<"sizes">>, Name} ->
                 Val = ?bin2uint(V),
-                [
-                    {other, {[{data_size, Val}]}},
-                    {sizes, {[
-                        {active, 0},
-                        {external, Val},
-                        {file, 0}
-                    ]}}
-                ];
+                {_, {Sizes}} = lists:keyfind(sizes, 1, Acc),
+                NewSizes = lists:keystore(Name, 1, Sizes, {Name, Val}),
+                lists:keystore(sizes, 1, Acc, {sizes, {NewSizes}});
             {?DB_STATS, _} ->
-                []
+                Acc
         end
-    end, erlfdb:wait(MetaFuture)),
+    end, [{sizes, {[]}}], erlfdb:wait(MetaFuture)),
 
     [CProp | MProps].
 
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