ETS 创建 return 值

Question

我正在使用 Elixir 1.6.3。我正在使用 Elixir 中的 Erlang :ets 模块，我对 :ets.new/2 函数的 return 值感到有点困惑。

根据 doc's example，在调用 :ets.new(:whatever, []) 时，我应该 returned 看起来是整数的值：

iex> table = :ets.new(:buckets_registry, [:set, :protected])
8207

然而，当我运行完全相同的代码在 iex 时，我得到一个参考：

iex(1)> table = :ets.new(:buckets_registry, [:set, :protected])     
#Reference<0.1885502827.460455937.234656>

那么，自文档编写以来有什么变化吗？还是只是一样，我对什么是参考感到困惑？

Answer 1

是的，ets:new 的 return 值在 Erlang/OTP 20.0 中从整数更改为引用。来自 the README:

  OTP-14094    Application(s): stdlib

               *** POTENTIAL INCOMPATIBILITY ***

               Optimized ETS operations by changing table identifier
               type from integer to reference. The reference enables a
               more direct mapping to the table with less potential
               lock contention and makes especially creation and
               deletion of tables scale much better.

               The change of the opaque type for the ETS table
               identifiers may cause failure in code that make faulty
               assumptions about this opaque type.

               The number of tables stored at one Erlang node *used*
               to be limited. This is no longer the case (except by
               memory usage). The previous default limit was about
               1400 tables and could be increased by setting the
               environment variable ERL_MAX_ETS_TABLES before starting
               the Erlang runtime system. This hard limit has been
               removed, but it is currently useful to set the
               ERL_MAX_ETS_TABLES anyway. It should be set to an
               approximate of the maximum amount of tables used. This
               since an internal table for named tables is sized using
               this value. If large amounts of named tables are used
               and ERL_MAX_ETS_TABLES hasn't been increased, the
               performance of named table lookup will degrade.

ETS 创建 return 值

ETS creation return value

reference

erlang

elixir

ets