johanna v0.2.5 Johanna
Simple wrapper for erlcron
,
the library providing testable cron like functionality for Erlang systems,
with the ability to arbitrarily set the time and place along
with fastforwarding through tests.
Examples (gracefully copy-pasted from original README
)
{{once, {3, 30, pm}},
{io, fwrite, ["Hello, world!~n"]}}
{{once, {12, 23, 32}},
{io, fwrite, ["Hello, world!~n"]}}
{{once, 3600},
{io, fwrite, ["Hello, world!~n"]}}
{{daily, {every, {23, sec}, {between, {3, pm}, {3, 30, pm}}}},
{io, fwrite, ["Hello, world!~n"]}}
{{daily, {3, 30, pm}},
fun() -> io:fwrite("It's three thirty~n") end}
{{daily, [{1, 10, am}, {1, 07, 30, am}]},
{io, fwrite, ["Bing~n"]}}
{{weekly, thu, {2, am}},
{io, fwrite, ["It's 2 Thursday morning~n"]}}
{{weekly, wed, {2, am}},
{fun() -> io:fwrite("It's 2 Wednesday morning~n") end}
{{weekly, fri, {2, am}},
{io, fwrite, ["It's 2 Friday morning~n"]}}
{{monthly, 1, {2, am}},
{io, fwrite, ["First of the month!~n"]}}
{{monthly, 4, {2, am}},
{io, fwrite, ["Fourth of the month!~n"]}}
Summary
Functions
Runs the given function recurrently at the time given
Cancels the job, previously started with at
/once
Runs the given function recurrently
Returns the DateTime
instance, currently set for erlcron
Sets the DateTime
instance for erlcron
. Useful in Timecop
-like scenarios
Sets the DateTime
instance for erlcron
on many nodes
Runs the given function every N
units (unit is :hr
, :min
or :sec
)
Runs the given function once
Replaces the job identified by reference (by cancelling the old one and placing the new one with the same reference)
Called when an application is started
Checks whether the job spec is valid
Functions
at(:erlcron.cron_time | :erlcron.seconds | Time.t, :erlcron.callable) :: :erlcron.job_ref
Runs the given function recurrently at the time given.
Examples
▶ Johanna.at({3, :pm}, fn -> IO.puts("¡Yay!") end)
▷ ... at 15:00, daily:
▷ "¡Yay!"
▶ Johanna.at({2, 45, :pm}, {IO, :puts, ["¡Yay!"]})
▷ ... at 14:45, daily:
▷ "¡Yay!"
Cancels the job, previously started with at
/once
.
Runs the given function recurrently.
Examples
▶ Johanna.cron({10, :am}, fn -> IO.puts("¡Yay!") end})
▷ ... at 10AM daily
▷ "¡Yay!"
Returns the DateTime
instance, currently set for erlcron
.
Examples
▶ Johanna.datetime()
▷ %DateTime{calendar: Calendar.ISO, day: 30, hour: 14, microsecond: {0, 0},
▷ minute: 2, month: 3, second: 43, std_offset: 0, time_zone: "Etc/UTC",
▷ utc_offset: 0, year: 2017, zone_abbr: "UTC"}
Sets the DateTime
instance for erlcron
. Useful in Timecop
-like scenarios.
Sets the DateTime
instance for erlcron
on many nodes.
every(Integer.t | :erlcron.duration, :erlcron.constraint | nil, :erlcron.callable) :: :erlcron.job_ref
Runs the given function every N
units (unit is :hr
, :min
or :sec
).
Examples
▶ Johanna.every(10, fn -> IO.puts("¡Yay!") end)
▷ ... every 10 secs
▷ "¡Yay!"
▶ Johanna.every({10, :sec}, fn -> IO.puts("¡Yay!") end)
▷ ... every 10 secs
▷ "¡Yay!"
▶ Johanna.every({1, :min}, {IO, :puts, ["¡Yay!"]})
▷ ... every 1 min
▷ "¡Yay!"
▶ Johanna.every(10, {:between, {1, :pm}, {4, :pm}}, fn -> IO.puts("¡Siesta!") end)
▷ ... every 10 secs from 1PM till 4PM
▷ "¡Siesta!"
once(:erlcron.cron_time | :erlcron.seconds | DateTime.t, :erlcron.callable) :: :erlcron.job_ref
Runs the given function once.
Examples
▶ Johanna.once(10, fn -> IO.puts("¡Yay!") end)
▷ ... 10 sec pause
▷ "¡Yay!"
Replaces the job identified by reference (by cancelling the old one and placing the new one with the same reference).
Examples
▶ ref = Johanna.at {7, :pm}, {IO, :puts, ["Yay"]}
▷ #Reference<0.0.5.28>
▶ Johanna.replace ref, {{:daily, {7, :pm}}, {IO, :puts, ["Yay"]}}
▷ #Reference<0.0.5.28>
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
.