修复 mongo 游标没有数据 hasNext 返回 true，以及无效关闭游标的问题 (#1653)

Co-authored-by: yy151474 <yy151474@alibaba-inc.com>

lualib/skynet/db/mongo.lua

@@ -14,6 +14,7 @@ local table = table
 local bson_encode =	bson.encode
 local bson_encode_order	= bson.encode_order
 local bson_decode =	bson.decode
+local bson_int64 = bson.int64
 local empty_bson = bson_encode {}
 
 local mongo	= {}
@@ -489,7 +490,10 @@ end
 
 function mongo_collection:findOne(query, projection)
 	local cursor = self:find(query, projection)
-	return cursor:hasNext() and cursor:next()
+	if cursor:hasNext() then
+		return cursor:next()
+	end
+	return nil
 end
 
 function mongo_collection:find(query, projection)
@@ -686,7 +690,7 @@ function mongo_cursor:hasNext()
 		else
 			if self.__cursor  and self.__cursor > 0 then
 				local name = self.__collection.name
-				response = database:runCommand("getMore", bson.int64(self.__cursor), "collection", name, "batchSize", self.__limit)
+				response = database:runCommand("getMore", bson_int64(self.__cursor), "collection", name, "batchSize", self.__limit)
 			else
 				-- no more
 				self.__document	= nil
@@ -719,6 +723,10 @@ function mongo_cursor:hasNext()
 			self.__limit = limit
 		end
 
+		if cursor.id == 0 and #self.__document == 0 then -- nomore
+			return false
+		end
+
 		return true
 	end
 
@@ -739,9 +747,9 @@ function mongo_cursor:next()
 end
 
 function mongo_cursor:close()
-	if self.__cursor then
+	if self.__cursor and self.__cursor > 0 then
 		local coll = self.__collection
-		coll.database:send_command("killCursors", coll.name, "cursors", {self.__cursor})
+		coll.database:send_command("killCursors", coll.name, "cursors", {bson_int64(self.__cursor)})
 		self.__cursor = nil
 	end
 end

test/testmongodb.lua

@@ -79,11 +79,20 @@ function test_find_and_remove()
 	db.testcoll:dropIndex("*")
 	db.testcoll:drop()
 
+	local cursor = db.testcoll:find()
+	assert(cursor:hasNext() == false)
+
 	db.testcoll:ensureIndex({test_key = 1}, {test_key2 = -1}, {unique = true, name = "test_index"})
 
 	ok, err, ret = db.testcoll:safe_insert({test_key = 1, test_key2 = 1})
 	assert(ok and ret and ret.n == 1, err)
 
+	cursor = db.testcoll:find()
+	assert(cursor:hasNext() == true)
+	local v = cursor:next()
+	assert(v)
+	assert(v.test_key == 1)
+
 	ok, err, ret = db.testcoll:safe_insert({test_key = 1, test_key2 = 2})
 	assert(ok and ret and ret.n == 1, err)