List.RemoveAll和List.FindAll结合产生的性能问题之后...

原代码：

当时entityList中的数据量：4704；length : 2

private static void OperateRemove ( List<Entity> entityList, int length) {

entityList.RemoveAll( delegate( Entity entity) {
         List<Entity >  list = entityList.FindAll( delegate( Entity innerEntity) {
               return entity.A== innerEntity.A

          } );
      return null != list && list .Count < length;
} );

}

第一方案：初步认为是数据未排序，所以FindAll会慢。所以

private static void OperateRemove ( List<Entity> entityList, int length) {

entityList.Sort( delegate( Entity entity1, HotelRoomPriceEntity entity2) {
         return entity1.A.CompareTo( entity2.A);
} );

entityList.RemoveAll( delegate( Entity entity) {
         List<Entity >  list = entityList.FindAll( delegate( Entity innerEntity) {
               return entity.A== innerEntity.A

          } );
      return null != list && list .Count < length;
} );

}

当时程序跑过之后，微秒时间为：7901

 

第二方案：看来问题瓶颈还是在FindAll，所以通过一次查询先把要删除的entity.A查找出来，后面集中删除。

private static void OperateRemove ( List<Entity> entityList, int length) {

           entityList.Sort( delegate( Entity entity1 , Entity entity2 ) {
                     return entity1.A.CompareTo( entity2.A);
            } );
            int eachACount = 0;
            int A= 0;
            int nextA= 0;
            List<int> lackAEntityList= new List<int>();
            foreach ( Entity entity in entityList) {
                if ( 0 == A) {
                    A= entity.A;
                    nextA= entity.A;
                }
                else {
                    nextA= entity.A;
                }
                if ( A != nextA) {
                    if ( length> eachACount ) {
                        lackAEntityList.Add( roomId );
                    }
                    A = nextA;
                    eachACount = 0;
                }
                eachACount ++;
            }
            entityList.RemoveAll( delegate( Entity entity) {
                return lackAEntityList.Exists( delegate( int A) {
                    return entity.A== A;
                } );
            } );

            }

当时程序跑过之后，微秒时间为：40

 

当然还有其他解决方案:如使用sortlist＋binarySearch,Etc.

不过40对我们来说，已经比较理想。

 

另外附上

目标：
        /// 根据A-List中的HotelID查找B-List中RoomID为0,
        /// 删除对应B-List中的有关于HotelID所有RoomId全为空的配备信息
        /// 同时也要删除A-List中对应的信息

        public List<RoomEntity> RemoveRoomIDAllEmpty()
        {
            ///创建存放RoomID不为空的HotelIDList
            List<Int32> hotelIdList = new List<int>();

            roomList.ForEach(delegate(RoomEntity re)
            {
                if (hotelList.Contains(re.HotelId))
                {
                    if (re.roomId != 0)
                    {
                        hotelIdList.Add(re.HotelId);
                    }
                }
            });

            //删除RoomList中的有关于HotelID所有RoomId全为空的配备信息
            roomList.RemoveAll(delegate(RoomEntity re)
            {
                return !hotelIdList.Contains(re.HotelId);
            });

            //删除HotelList中的对应信息
            hotelList.RemoveAll(delegate(Int32 i)
            {
                return !hotelIdList.Contains(i);
            });

            return roomList;
        }

       List<Int32> hotelList = new List<Int32> {
            1,2,3,4,5,6,7,8,9,10
        };       

       List<RoomEntity> roomList = new List<RoomEntity> {
            new RoomEntity{ HotelId =1,roomId=1111},
            new RoomEntity{ HotelId =1,roomId=0},
            new RoomEntity{ HotelId =1,roomId=1111},
            new RoomEntity{ HotelId =1,roomId=0},
            new RoomEntity{ HotelId =1,roomId=1111},
            new RoomEntity{ HotelId =2,roomId=0},
            new RoomEntity{ HotelId =2,roomId=0},
            new RoomEntity{ HotelId =2,roomId=0},
            new RoomEntity{ HotelId =2,roomId=0},
            new RoomEntity{ HotelId =4,roomId=1111},
            new RoomEntity{ HotelId =5,roomId=1111},
            new RoomEntity{ HotelId =3,roomId=1111},
            new RoomEntity{ HotelId =4,roomId=1111},
            new RoomEntity{ HotelId =1,roomId=1111},
            new RoomEntity{ HotelId =6,roomId=1111},
            new RoomEntity{ HotelId =1,roomId=1111},
            new RoomEntity{ HotelId =5,roomId=1111},
            new RoomEntity{ HotelId =8,roomId=1111},
            new RoomEntity{ HotelId =7,roomId=0},
            new RoomEntity{ HotelId =4,roomId=1111},
            new RoomEntity{ HotelId =8,roomId=1111},
            new RoomEntity{ HotelId =9,roomId=1111},
            new RoomEntity{ HotelId =10,roomId=0},
            new RoomEntity{ HotelId =10,roomId=0}
        };