hammer v5.0.0 Hammer.Application View Source
Hammer application, responsible for starting the backend worker pools.
Configured with the :hammer
environment key:
:backend
, Either a tuple of{module, config}
, or a keyword-list of separate, named backends. Examples:{Hammer.Backend.ETS, []}
,[ets: {Hammer.Backend.ETS, []}, ...]
:suppress_logs
, if set totrue
, stops all log messages from Hammer
General Backend Options
Different backends take different options, but all will accept the following options, and with the same effect:
:expiry_ms
(int): expiry time in milliseconds, after which a bucket will be deleted. The exact mechanism for cleanup will vary by backend:pool_size
(int): size of the backend worker pool:pool_max_overflow
int(): number of extra workers the pool is permitted to spawn when under pressure. The worker pool (managed by the poolboy library) will automatically create and destroy workers up to the max-overflow limit
Example of a single backend:
config :hammer,
backend: {Hammer.Backend.ETS, [expiry_ms: 60_000 * 60 * 2]}
Example of config for multiple-backends:
config :hammer,
backend: [
ets: {
Hammer.Backend.ETS,
[
ets_table_name: :hammer_backend_ets_buckets,
expiry_ms: 60_000 * 60 * 2,
cleanup_interval_ms: 60_000 * 2,
pool_size: 2,
pool_max_overflow: 4
]
},
redis: {
Hammer.Backend.Redis,
[
expiry_ms: 60_000 * 60 * 2,
redix_config: [host: "localhost", port: 6379]
]
}
]
Link to this section Summary
Functions
Called when an application is started
Link to this section Functions
Called when an application is started.
This function is called when an application is started using
Application.start/2
(and functions on top of that, such as
Application.ensure_started/2
). This function should start the top-level
process of the application (which should be the top supervisor of the
application’s supervision tree if the application follows the OTP design
principles around supervision).
start_type
defines how the application is started:
:normal
- used if the startup is a normal startup or if the application is distributed and is started on the current node because of a failover from another node and the application specification key:start_phases
is:undefined
.{:takeover, node}
- used if the application is distributed and is started on the current node because of a failover on the nodenode
.{:failover, node}
- used if the application is distributed and is started on the current node because of a failover on nodenode
, and the application specification key:start_phases
is not:undefined
.
start_args
are the arguments passed to the application in the :mod
specification key (e.g., mod: {MyApp, [:my_args]}
).
This function should either return {:ok, pid}
or {:ok, pid, state}
if
startup is successful. pid
should be the PID of the top supervisor. state
can be an arbitrary term, and if omitted will default to []
; if the
application is later stopped, state
is passed to the stop/1
callback (see
the documentation for the c:stop/1
callback for more information).
use Application
provides no default implementation for the start/2
callback.
Callback implementation for Application.start/2
.