| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
Control.AutoUpdate
Description
A common problem is the desire to have an action run at a scheduled
interval, but only if it is needed. For example, instead of having
every web request result in a new getCurrentTime call, we'd like to
have a single worker thread run every second, updating an IORef.
However, if the request frequency is less than once per second, this is
a pessimization, and worse, kills idle GC.
This library allows you to define actions which will either be performed by a dedicated thread or, in times of low volume, will be executed by the calling thread.
- data UpdateSettings a
- defaultUpdateSettings :: UpdateSettings ()
- updateFreq :: UpdateSettings a -> Int
- updateSpawnThreshold :: UpdateSettings a -> Int
- updateAction :: UpdateSettings a -> IO a
- mkAutoUpdate :: UpdateSettings a -> IO (IO a)
Type
data UpdateSettings a
Settings to control how values are updated.
This should be constructed using defaultUpdateSettings and record
update syntax, e.g.:
let set = defaultUpdateSettings { updateAction = getCurrentTime }
Since 0.1.0
defaultUpdateSettings :: UpdateSettings ()
Default value for creating an UpdateSettings.
Since 0.1.0
Accessors
updateFreq :: UpdateSettings a -> Int
Microseconds between update calls. Same considerations as
threadDelay apply.
Default: 1 second (1000000)
Since 0.1.0
updateSpawnThreshold :: UpdateSettings a -> Int
NOTE: This value no longer has any effect, since worker threads are dedicated instead of spawned on demand.
Previously, this determined: How many times the data must be requested before we decide to spawn a dedicated thread.
Default: 3
Since 0.1.0
updateAction :: UpdateSettings a -> IO a
Action to be performed to get the current value.
Default: does nothing.
Since 0.1.0
Creation
mkAutoUpdate :: UpdateSettings a -> IO (IO a)
Generate an action which will either read from an automatically updated value, or run the update action in the current thread.
Since 0.1.0