我正在使用Elixir 1.6.3。我正在使用:ets
Elixir中的Erlang模块,但对该:ets.new/2
函数的返回值有些困惑。
根据doc的示例,在调用时:ets.new(:whatever, [])
,应该返回似乎是整数值的值:
iex> table = :ets.new(:buckets_registry, [:set, :protected])
8207
但是,当我在中运行完全相同的代码时iex
,会得到一个参考:
iex(1)> table = :ets.new(:buckets_registry, [:set, :protected])
#Reference<0.1885502827.460455937.234656>
那么,自编写文档以来,有什么改变吗?还是一样,我对引用是什么感到困惑?
是的,ets:new
在Erlang / OTP 20.0中,返回值从整数更改为引用。从自述文件:
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.
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