hammer v5.0.0 Hammer.Backend.ETS View Source
An ETS backend for Hammer
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 bucketcleanup_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
Functions
Returns a specification to start this module under a supervisor
Record a hit in the bucket identified by key
Record a hit in the bucket identified by key
, with a custom increment
Delete all buckets associated with id
Retrieve information about the bucket identified by key
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Link to this section Types
bucket_info() :: {key :: bucket_key, count :: integer, created :: integer, updated :: integer}
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
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 :: 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 :: pid, id :: String.t) :: {:ok, count_deleted :: integer} | {:error, reason :: any}
Delete all buckets associated with id
.
get_bucket(pid :: pid, key :: bucket_key) :: {:ok, info :: bucket_info} | {:ok, nil} | {:error, reason :: any}
Retrieve information about the bucket identified by key
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 callingSupervisor.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
.