uevent::onidle(3tcl) User events uevent::onidle(3tcl)__________________________________________________________________________________________________________________________________________________NAME
uevent::onidle - Request merging and deferal to idle time
SYNOPSIS
package require Tcl 8.4
package require uevent::onidle ?0.1?
package require logger
::uevent::onidle objectName commandprefix
objectName request
_________________________________________________________________DESCRIPTION
This package provides objects which can merge multiple requestes for an action and execute the action the moment the system (event loop)
becomes idle. The action to be run is configured during object construction.
API
The package exports a class, uevent::onidle, as specified below.
::uevent::onidle objectName commandprefix
The command creates a new onidle object with an associated global Tcl command whose name is objectName. This command may be used to
invoke various operations on the object.
The commandprefix is the action to perform when the event loop is idle and the user asked for it using the method request (See
below).
The object commands created by the class commands above have the form:
objectName request
This method requests the execution of the command prefix specified during the construction of objectName the next time the event
loop is idle. Multiple requests are merged and cause only one execution of the command prefix.
EXAMPLES
Examples of this type of deferal are buried in the (C-level) implementations all the Tk widgets, defering geometry calculations and window
redraw activity in this manner.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category uevent
of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
KEYWORDS
callback, deferal, event, idle, merge, on-idle
COPYRIGHT
Copyright (c) 2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
uev 0.1 uevent::onidle(3tcl)
Check Out this Related Man Page
cache::async(n) In-memory caches cache::async(n)
__________________________________________________________________________________________________________________________________________________NAME
cache::async - Asynchronous in-memory cache
SYNOPSIS
package require Tcl 8.4
package require cache::async ?0.3?
::cache::async objectName commandprefix ?options...?
objectName get key donecmdprefix
objectName set key value
objectName unset key
objectName exists key
objectName clear ?key?
_________________________________________________________________DESCRIPTION
This package provides objects which cache data in memory, and operate asynchronously with regard to request and responses. The objects are
agnostic with regard to cache keys and values, and unknown methods are delegated to the provider of cached data. These two properties make
it easy to use caches as a facade for any data provider.
API
The package exports a class, cache::async, as specified below.
::cache::async objectName commandprefix ?options...?
The command creates a new cache object with an associated global Tcl command whose name is objectName. This command may be used to
invoke various operations on the object.
The commandprefix is the action to perform when an user asks for data in the cache and the cache doesn't yet know about the key.
When run the commandprefix is given three additional arguments, the string get, the key requested, and the cache object itself, in
the form of its object command, in this order. The execution of the action is done in an idle-handler, decoupling it from the origi-
nal request.
The only supported option is
-full-async-results
This option defines the behaviour of the cache for when requested keys are known to the cache at the time of get request. By
default such requeste are responded to asynchronously as well. Setting this option to false forces the cache to respond to
them synchronuously, although still through the specified callback.
The object commands created by the class commands above have the form:
objectName get key donecmdprefix
This method requests the data for the key from the cache. If the data is not yet known the command prefix specified during construc-
tion of the cache object is used to ask for this information.
Whenever the information is/becomes available the donecmdprefix will be run to transfer the result to the caller. This command pre-
fix is invoked with either 2 or 3 arguments, i.e.
[1] The string set, the key, and the value.
[2] The string unset, and the key.
These two possibilities are used to either signal the value for the key, or that the key has no value defined for it. The latter is dis-
tinct from the cache not knowing about the key.
For a cache object configured to be fully asynchronous (default) the donecmdprefix is always run in an idle-handler, decoupling it from the
request. Otherwise the callback will be invoked synchronously when the key is known to the cache at the time of the invokation.
Another important part of the cache's behaviour, as it is asynchronous it is possible that multiple get requests are issued for the same
key before it can respond. In that case the cache will issue only one data request to the provider, for the first of these, and suspend the
others, and then notify all of them when the data becomes available.
objectName set key value
objectName unset key
These two methods are provided to allow users of the cache to make keys known to the cache, as either having a value, or as unde-
fined.
It is expected that the data provider (see commandprefix of the constructor) uses them in response to data requests for unknown
keys.
Note how this matches the cache's own API towards its caller, calling the donecmd of get-requests issued to itself with either "set
key value" or "unset key", versus issuing get-requests to its own provider with itself in the place of the donecmd, expecting to be
called with either "set key value" or "unset key".
This also means that these methods invoke the donecmd of all get-requests waiting for information about the modified key.
objectName exists key
This method queries the cache for knowledge about the key and returns a boolean value. The result is true if the key is known, and
false otherwise.
objectName clear ?key?
This method resets the state of either the specified key or of all keys known to the cache, making it unkown. This forces future
get-requests to reload the information from the provider.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category cache of
the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
KEYWORDS
asynchronous, cache, callback, synchronous
COPYRIGHT
Copyright (c) 2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
cache 0.3 cache::async(n)