Krug.DistributedMnesiaSqlCache (Krug v1.1.40) View Source

Utilitary module to handle Erlang Mnesia Database. Mnesia Database has single instance mode and also distributed mode that is purpose of this module. Single instance way don't allow us to improve horizontal scalability when we need.

Link to this section Summary

Functions

Add a new table in runtime execution to mnesia schema and replicate to other nodes. Return true or false.

Provides cache functionality to clear SQL queries result. Return true or false.

Almost the same that "init_cluster". The diference is that cluster_ips will be calculated to be all range of machine local network according the network mask range (/16 or /24).

Provides cache functionality to load SQL queries result. Return the cache result or nil.

Provides cache functionality to store SQL queries result. Return true or false.

Link to this section Functions

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add_runtime_table(table_name)

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Add a new table in runtime execution to mnesia schema and replicate to other nodes. Return true or false.

If table already was created in runtime, keep the actual table and return true. If table has same name from a table created in initialization, the operation will fail and will return false. You should keep control about the already created tables.

"table_name" should be an atom.

Requires mnesia already be started.

Provides cache functionality to clear SQL queries result. Return true or false.

Requires mnesia already be started.

If you wish you application be able to scalabity then should be used

init_cluster(cluster_name,cluster_ips,ips_separator,disc_copies,table_names)

function on application startup.

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init_auto_cluster(cluster_name, cluster_cookie, disc_copies \\ false, table_names \\ [], connection_timeout \\ nil)

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Almost the same that "init_cluster". The diference is that cluster_ips will be calculated to be all range of machine local network according the network mask range (/16 or /24).

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init_cluster(cluster_name, cluster_cookie, cluster_ips, ips_separator \\ "|", disc_copies \\ false, table_names \\ [], connection_timeout \\ nil)

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Start the mnesia cluster. To be used on application start.

Example

defmodule <Your_App_Main_Module_Name>.Application do

  @moduledoc false

  use Application

  alias Krug.DistributedMnesiaSqlCache


  def start(_type, _args) do
    Supervisor.start_link(children(), opts())
  end

  defp children() do
      [
        ...
        <Your_App_Main_Module_Name>.DistributedMnesiaSqlCacheTaskStarter, # calls Krug.DistributedMnesiaSqlCache.init_cluster(...)
        ...
      ]
  end

  defp opts() do 
      [strategy: :one_for_one, name: <Your_App_Main_Module_Name>.Supervisor]
  end 
  
end
defmodule <Your_App_Main_Module_Name>.DistributedMnesiaSqlCacheConfigTaskStarter do
  def child_spec(opts) do
    %{id: __MODULE__,start: {__MODULE__, :start_link, [opts]}}
  end

  def start_link(opts) do
    Supervisor.start_link([{<Your_App_Main_Module_Name>.DistributedMnesiaSqlCacheConfigTask,opts}], strategy: :one_for_one)
  end
end
defmodule <Your_App_Main_Module_Name>.DistributedMnesiaSqlCacheConfigTask do

  use Task
  alias Krug.DistributedMnesiaSqlCache

  def start_link(opts) do
    Task.start_link(__MODULE__, :run, [opts])
  end

  def run(_opts) do
    cluster_cookie = "echo"
    cluster_name = "echo"
    cluster_ips = "192.168.1.12X "
    ips_separator = "X" 
    table_names = [
      :users,
      :log,
      :other_table
    ]  
  
    cluster_name
      |> DistributedMnesiaSqlCache.init_cluster(cluster_cookie,cluster_ips,ips_separator,true,table_names)
  end

end
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load_from_cache(table_name, normalized_sql, params)

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Provides cache functionality to load SQL queries result. Return the cache result or nil.

Requires mnesia already be started.

If you wish you application be able to scalabity then should be used

init_cluster(cluster_name,cluster_ips,ips_separator,disc_copies,table_names)

function on application startup.

Link to this function

put_cache(table_name, normalized_sql, params, resultset, amount_to_keep \\ 200)

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Provides cache functionality to store SQL queries result. Return true or false.

Keep the "amount_to_keep" most recent created/loaded entries from "table_name" table. All other entries will be removed/deleted. Return true or false.

Requires mnesia already be started.

If you wish you application be able to scalabity then should be used

init_cluster(cluster_name,cluster_ips,ips_separator,disc_copies,table_names)

function on application startup.