Mnemonics
Read only data store for Elixir: fast, concurrently, for large data & hot reloadable.
Mnemonics is analogous to Ruby’s ActiveHash in it’s usecase.
Installation
Add mnemonics
to your list of dependencies in mix.exs
:
def deps do
[
{:mnemonics, "~> 0.2"}
]
end
Usage
Config Mnemonics ets_dir. config.exs
:
config :mnemonics, :ets_dir, "priv/repo/seeds"
Create an example.ets
by :ets.tab2file/3
. Then put it into the ets_dir. The examples.ets
stores {:example1, %{id: :example1}}
.
priv/
└repo/
└seeds/
└examples.ets
Create an Example
module, use Mnemonics & load.
defmodule Example do
use Mnemonics, table_name: :examples
end
Example.load 1
We can lookup the table.
:ets.lookup Example.table_name(1), :example1
Let’s reload a new table. Put a new examples.ets
into the ets_dir & load it with a new version number.
Example.load 2
We can lookup the new table.
:ets.lookup Example.table_name(2), :example1
snap = Mnemonics.Snap.snap Mnemonics.Snap.new, 2, %{}
:ets.lookup Example.table_name(snap), :example1
Mnemonics has cache function named Mnemonics.Snap
.
snap = Mnemonics.Snap.snap Mnemonics.Snap.new, 2, %{}
get_and_update_in snap[:examples].cache[:example1], fn
nil ->
example = :ets.lookup Example.table_name(snap), :example1
{example, example}
example -> {example, example}
end
:ets.new/2 Option
- Should
:public
or:protected
.:protected
(default) is recommended. - Can’t
:named_table
. {:read_concurrency, true}
is recommended.