hammer v6.0.0 Hammer.Backend.ETS View Source

An ETS backend for Hammer

Note: This backend is suitable for development, testing, and small single-node deployments, but should not be used for production workloads.

The public API of this module is used by Hammer to store information about rate-limit ‘buckets’. A bucket is identified by a key, which is a tuple {bucket_number, id}. The essential schema of a bucket is: {key, count, created_at, updated_at}, although backends are free to store and retrieve this data in whichever way they wish.

Use start or start_link to start the server:

{:ok, pid} = Hammer.Backend.ETS.start_link(args)

args is a keyword list:

ets_table_name: (atom) table name to use, defaults to :hammer_ets_buckets
expiry_ms: (integer) time in ms before a bucket is auto-deleted, should be larger than the expected largest size/duration of a bucket
cleanup_interval_ms: (integer) time between cleanup runs,

Example:

Hammer.Backend.ETS.start_link(
  expiry_ms: 1000 * 60 * 60,
  cleanup_interval_ms: 1000 * 60 * 10
)

Link to this section Summary

Types

bucket_info()

bucket_key()

Functions

child_spec(arg)

Returns a specification to start this module under a supervisor

count_hit(pid, key, now)

Record a hit in the bucket identified by key

count_hit(pid, key, now, increment)

Record a hit in the bucket identified by key, with a custom increment

delete_buckets(pid, id)

Delete all buckets associated with id

get_bucket(pid, key)

Retrieve information about the bucket identified by key

init(args)

Invoked when the server is started. start_link/3 or start/3 will block until it returns

start()

start(args)

start_link()

start_link(args)

stop()

Link to this section Types

bucket_info()

bucket_info() :: {key :: bucket_key, count :: integer, created :: integer, updated :: integer}

bucket_key()

bucket_key() :: {bucket :: integer, id :: String.t}

Link to this section Functions

child_spec(arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

count_hit(pid, key, now)

count_hit(pid :: pid, key :: bucket_key, now :: integer) ::
  {:ok, count :: integer} |
  {:error, reason :: any}

Record a hit in the bucket identified by key

count_hit(pid, key, now, increment)

count_hit(pid :: pid, key :: bucket_key, now :: integer, increment :: integer) ::
  {:ok, count :: integer} |
  {:error, reason :: any}

Record a hit in the bucket identified by key, with a custom increment

delete_buckets(pid, id)

delete_buckets(pid :: pid, id :: String.t) ::
  {:ok, count_deleted :: integer} |
  {:error, reason :: any}

Delete all buckets associated with id.

get_bucket(pid, key)

get_bucket(pid :: pid, key :: bucket_key) ::
  {:ok, info :: bucket_info} |
  {:ok, nil} |
  {:error, reason :: any}

Retrieve information about the bucket identified by key

init(args)

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

The GenServer is disabled by configuration but might be enabled later.
An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

start()

start(args)

start_link()

start_link(args)

stop()