| Safe Haskell | Safe-Infered |
|---|
Ganeti.Utils.AsyncWorker
Description
Provides a general functionality for workers that run on the background and perform some task when triggered.
Each task can process multiple triggers, if they're coming faster than the tasks are being processed.
Properties:
- If a worked is triggered, it will perform its action eventually. (i.e. it won't miss a trigger).
- If the worker is busy, the new action will start immediately when it finishes the current one.
- If the worker is idle, it'll start the action immediately.
- If the caller uses
triggerAndWait, the call will return just after the earliest action following the trigger is finished. - If the worker finishes an action and there are no pending triggers since the start of the last action, it becomes idle and waits for a new trigger.
- data TriggerState i a
- addTrigger :: Monoid i => i -> Maybe (MVar a) -> TriggerState i a -> TriggerState i a
- data AsyncWorker i a = AsyncWorker ThreadId (IORef (TriggerState i a)) (MVar ())
- mkAsyncWorker :: (Monoid i, MonadBaseControl IO m) => (i -> m a) -> m (AsyncWorker i a)
- mkAsyncWorker_ :: MonadBaseControl IO m => m a -> m (AsyncWorker () a)
- triggerInternal :: (MonadBase IO m, Monoid i) => i -> Maybe (MVar a) -> AsyncWorker i a -> m ()
- trigger :: (MonadBase IO m, Monoid i) => i -> AsyncWorker i a -> m ()
- trigger_ :: MonadBase IO m => AsyncWorker () a -> m ()
- triggerAndWaitMany :: (Traversable t, MonadBase IO m, Monoid i) => i -> t (AsyncWorker i a) -> m (t a)
- triggerAndWaitMany_ :: (Traversable t, MonadBase IO m) => t (AsyncWorker () a) -> m (t a)
- triggerAndWait :: (MonadBase IO m, Monoid i) => i -> AsyncWorker i a -> m a
- triggerAndWait_ :: MonadBase IO m => AsyncWorker () a -> m a
Documentation
data TriggerState i a Source
addTrigger :: Monoid i => i -> Maybe (MVar a) -> TriggerState i a -> TriggerState i aSource
data AsyncWorker i a Source
Represent an asynchronous worker whose single action execution returns a
value of type a.
Constructors
| AsyncWorker ThreadId (IORef (TriggerState i a)) (MVar ()) |
mkAsyncWorker :: (Monoid i, MonadBaseControl IO m) => (i -> m a) -> m (AsyncWorker i a)Source
Given an action, construct an AsyncWorker.
mkAsyncWorker_ :: MonadBaseControl IO m => m a -> m (AsyncWorker () a)Source
Given an action, construct an AsyncWorker with no input.
triggerInternal :: (MonadBase IO m, Monoid i) => i -> Maybe (MVar a) -> AsyncWorker i a -> m ()Source
trigger :: (MonadBase IO m, Monoid i) => i -> AsyncWorker i a -> m ()Source
Trigger a worker, letting it run its action asynchronously, but do not wait for the result.
trigger_ :: MonadBase IO m => AsyncWorker () a -> m ()Source
Trigger a worker with no input, letting it run its action asynchronously, but do not wait for the result.
triggerAndWaitMany :: (Traversable t, MonadBase IO m, Monoid i) => i -> t (AsyncWorker i a) -> m (t a)Source
Trigger a list of workers and wait until all the actions following these triggers finish. Returns the results of the actions.
Note that there is a significant difference between triggerAndWaitMany
and mapM triggerAndWait. The latter runs all the actions of the workers
sequentially, while the former runs them in parallel.
triggerAndWaitMany_ :: (Traversable t, MonadBase IO m) => t (AsyncWorker () a) -> m (t a)Source
Trigger a list of workers with no input and wait until all the actions following these triggers finish. Returns the results of the actions.
See triggetAndWaitMany.
triggerAndWait :: (MonadBase IO m, Monoid i) => i -> AsyncWorker i a -> m aSource
Trigger a worker and wait until the action following this trigger finishes. Return the result of the action.
triggerAndWait_ :: MonadBase IO m => AsyncWorker () a -> m aSource
Trigger a worker with no input and wait until the action following this trigger finishes. Return the result of the action.