TRY_FLAG
#define READ_LOCK_TRY (READ_LOCK | TRY_FLAG)
#define WRITE_LOCK_TRY (WRITE_LOCK | TRY_FLAG)
try_flag = (rd_wr & TRY_FLAG);
rd_wr &= ~TRY_FLAG;
try_flag = (rd_wr & TRY_FLAG);
rd_wr &= ~TRY_FLAG;
#define READ_LOCK_TRY (READ_LOCK | TRY_FLAG)
#define WRITE_LOCK_TRY (WRITE_LOCK | TRY_FLAG)
try_flag = (rd_wr & TRY_FLAG);
rd_wr &= ~TRY_FLAG;