Show statistics in a query result meta

Fixed resulting_object_cnt counter in case of a filter by 1:1
connection.

Part of #71.

Author: Totktonada

graphql/accessor_general.lua

@@ -878,6 +878,12 @@ local function process_tuple(self, state, tuple, opts)
         return true -- skip pivot item too
     end
 
+    -- Don't count subrequest resulting objects (needed for filtering) into
+    -- count of object we show to an user as a result.
+    -- XXX: It is better to have an option to control whether selected objects
+    -- will be counted as resulting ones.
+    local saved_resulting_object_cnt = qstats.resulting_object_cnt
+
     -- make subrequests if needed
     for k, v in pairs(filter) do
         if obj[k] == nil then
@@ -891,6 +897,8 @@ local function process_tuple(self, state, tuple, opts)
         end
     end
 
+    qstats.resulting_object_cnt = saved_resulting_object_cnt
+
     -- filter out non-matching objects
     local match = utils.is_subtable(obj, filter) and
         match_using_re(obj, pcre)
@@ -1060,6 +1068,13 @@ local function select_internal(self, collection_name, from, filter, args, extra)
         -- fullscan
         local primary_index = self.funcs.get_primary_index(self,
             collection_name)
+
+        -- count full scan select request
+        extra.qcontext.statistics.select_requests_cnt =
+            extra.qcontext.statistics.select_requests_cnt + 1
+        extra.qcontext.statistics.full_scan_select_requests_cnt =
+            extra.qcontext.statistics.full_scan_select_requests_cnt + 1
+
         for _, tuple in primary_index:pairs() do
             assert(pivot == nil,
                 'offset for top-level objects must use a primary index')
@@ -1102,6 +1117,12 @@ local function select_internal(self, collection_name, from, filter, args, extra)
 
         local tuple_count = 0
 
+        -- count index select request
+        extra.qcontext.statistics.select_requests_cnt =
+            extra.qcontext.statistics.select_requests_cnt + 1
+        extra.qcontext.statistics.index_select_requests_cnt =
+            extra.qcontext.statistics.index_select_requests_cnt + 1
+
         for _, tuple in index:pairs(index_value, iterator_opts) do
             tuple_count = tuple_count + 1
             -- check full match constraint
@@ -1287,7 +1308,10 @@ local function init_qcontext(accessor, qcontext)
     local settings = accessor.settings
     qcontext.statistics = {
         resulting_object_cnt = 0,
-        fetched_object_cnt = 0
+        fetched_object_cnt = 0,
+        select_requests_cnt = 0,
+        full_scan_select_requests_cnt = 0,
+        index_select_requests_cnt = 0,
     }
     qcontext.deadline_clock = clock.monotonic64() +
         settings.timeout_ms * 1000 * 1000

graphql/core/execute.lua

@@ -125,11 +125,12 @@ evaluateSelections = function(objectType, object, selections, context)
   return result
 end
 
-return function(schema, tree, rootValue, variables, operationName)
+return function(schema, tree, rootValue, variables, operationName, opts)
+  local opts = opts or {}
   local context = query_util.buildContext(schema, tree, rootValue, variables, operationName)
   -- The field is passed to resolve function within info attribute.
   -- Can be used to store any data within one query.
-  context.qcontext = {}
+  context.qcontext = opts.qcontext or {}
   local rootType = schema[context.operation.operation]
 
   if not rootType then

graphql/impl.lua

@@ -40,11 +40,12 @@ local function gql_execute(qstate, variables, operation_name)
     check(operation_name, 'operation_name', 'string', 'nil')
 
     local root_value = {}
+    local qcontext = {}
 
     local traceback
     local ok, data = xpcall(function()
         return execute(state.schema, qstate.ast, root_value, variables,
-            operation_name)
+            operation_name, {qcontext = qcontext})
     end, function(err)
         traceback = debug.traceback()
         return err
@@ -55,6 +56,9 @@ local function gql_execute(qstate, variables, operation_name)
     end
     return {
         data = data,
+        meta = {
+            statistics = qcontext.statistics,
+        }
     }
 end