nsweeting/stat_buffer

StatBuffer provides an efficient way to maintain persistable stat counts.

StatBuffer

StatBuffer is an efficient way to maintain a local incrementable count with a given key that can later be flushed to persistent storage. In fast moving systems, this provides a scalable way keep track of counts without putting heavy loads on a database.

Installation

The package can be installed by adding stat_buffer to your list of dependencies in mix.exs:

def deps do
  [
    {:stat_buffer, "~> 1.2"}
  ]
end

Documentation

Please see HexDocs for additional documentation. This readme provides a brief overview, but it is recommended that the docs are used.

Creating a Buffer

We can start off by creating our buffer. This is simply a module that uses StatBuffer and implements the handle_flush/2 callback.

defmodule Buffer do
  use StatBuffer

  def handle_flush(key, counter) do
    # do database stuff...

    # we must return an :ok atom
    :ok
  end
end

We then must add the buffer to our supervision tree.

children = [
  Buffer
]

There are some configruable options available for our buffers. You can read more about them here. These options can be passed when creating our buffer.

  use StatBuffer, interval: 10_000

With our buffer started, we can now increment key counters. A key can be any valid term.

Buffer.increment("mykey") # increments by 1

Buffer.increment("mykey", 10) # increments by 10

And we're done! Our counter will be flushed using our handle_flush/2 callback after the default interval period. Dead counters are automatically removed.