System.Hiernotify

Description

This module offers a daemon polling a filesystem hierarchy to notify changes to a given IO action.

This example runs a n seconds console reporter for the activity in hierarchy p. Polling delay is 3 seconds. And it waits 2 silent polling samples before reporting to console.

Medium responsiveness for an isolated change is then 3 * (2 + 1/2) seconds

 testReport 	:: Int -- ^ life span for the program
		-> FilePath -- ^ hierarchy top
		-> IO () -- ^ block for life span
 testReport n p = do 
	k <- onDifferenceDaemon  3 2 (not . isPrefixOf ".") p  (print . report) -- boot the onDifferenceDaemon
	threadDelay $ n * 1000000 -- wait n seconds
	k -- kill the onDifferenceDaemon
	where report (Difference nn dd mm) = map length [nn,dd,mm]

Synopsis

Documentation

data Difference Source

Difference datatype containing a difference as three sets of paths

Constructors

Difference
Fields created :: [FilePath] Files appeared deleted :: [FilePath] Files disappeared modified :: [FilePath] Files modified

Instances

Eq Difference
Show Difference
Monoid Difference

onDifferenceDaemon Source

Arguments

:: Int	polling delay in seconds
-> Int	number of no-change delays before running the action
-> (FilePath -> Bool)	path filter
-> FilePath	file hierarchy top
-> (Difference -> IO ())	the action executed on a modification
-> IO (IO ())	the action to kill the daemon

Execute an action on file changes in a hierarchy.