Requester::Requester Class Reference

Requesters are responsible for providing the data requested via a "get" statement in tests.cfg (Monitor::Tester). More...

Inheritance diagram for Requester::Requester:

Public Class Methods
	new ()
	create a requester.

Public Object Methods
void	register (list domains)
	Register a requester for one or multiple domains.
hashref	request (hashref env, scalar domain, arrayref variables)
	Computes (or requests) the values of the variables listed in variables.
boolean	fail_novar (boolean fail)
	Not used any more?
hashref	getinfo (arrayref gets, arrayref indexes)
	Called by the default request() method with gets set to the list of the variables, indexes set to the list of variable indexes to be retrieved.
hashref	getwalk (arrayref gets, arrayref indexes, arrayref walks)
	Similiar to getinfo(), but getwalk() is called by the default request() method if the request includes a "walk" and passes the list of variables to be walked via the walks parameter.
boolean	available (hashref env)
	Determine if a requester is willing to perform (handle requests) for a given tester environment.
boolean	command_available (list cmd)
	Tests if cmd is runnable - usually called by classes inherited from Requester::Requester in their available() method in order to find out if a system command they require is present or not.
int	criticalness (int criticalness)
	Get/Set the criticalness of a handler.
int	consumes (int consumes)
	Get/set consume level of a handler.

Public Functions
list	probe_consumes (hashref env, arrayref variables)
	Given a list of variable names and an environment, probe_consumes() will try to determine the criticalness/consumes values for the requests that it takes to get all those variable's values.
hashref	get (hashref env, arrayref variables)
	Given a list of variable names and a tester environment requests all the variables and returns the result in a hash ref.
Requester::Requester	get_handler (scalar domain)
	Given the name of a domain this function searches for a request handler that is willing to perform requests for this domain.
boolean	load_module (scalar module)
	Given the name of a module tries to dynamically load Requester::modulename.

Protected Functions
protected void	preexit ()
	This function is called during program shutdown.
protected hashref	_get (hashref env, arrayref variables, scalar probe_only)
	Implements both the get() and probe_consumes() call.
protected void	set_cache (hashref env, scalar domain, scalar name, hashref value)
	Given a domain, variable name and a value stores the value in the cache under the given domain/name.
protected void	clear_cache ()
	Clear the variable cache.

Detailed Description

Requesters are responsible for providing the data requested via a "get" statement in tests.cfg (Monitor::Tester).

Member Function Documentation

protected hashref Requester::Requester::_get	(	hashref	env,
		arrayref	variables,
		scalar	probe_only
	)

Implements both the get() and probe_consumes() call.

Parameters

env	Tester environment
variables	List of variable names
probe_only	If set use probe_consumes() semantics, otherwise get() is performed

Returns

Hashref compatible with get() if called with probe_only not set, otherwise a hashref with the keys being the names of domains that need a requester to be called.

boolean Requester::Requester::available

(

hashref

env

)

Determine if a requester is willing to perform (handle requests) for a given tester environment.

Usually, available() will return false if some required system command is not installed, some API is missing, the test works only against a local machine but the target host is not the local machine, etc.

Parameters

env	Tester environment

Returns

true if requester is willing to handle requests, false otherwise

protected void Requester::Requester::clear_cache

(

)

Clear the variable cache.

boolean Requester::Requester::command_available

(

list

cmd

)

Tests if cmd is runnable - usually called by classes inherited from Requester::Requester in their available() method in order to find out if a system command they require is present or not.

Note

The command in question is actually executed via system(), so it is required that the cmd argument includes "save" command line options ensuring that no harm is done to the system and Big Sister.

Parameters

cmd	The command to be tested for availability.

int Requester::Requester::consumes

(

int

consumes

)

Get/set consume level of a handler.

The higher the "consumes" figure is the more other handlers will suffer if running in parallel with this handler.

Parameters

consumes

(optional) if defined, set the consumes figure to this value

Returns

The current 'consumes' figure.

int Requester::Requester::criticalness

(

int

criticalness

)

Get/Set the criticalness of a handler.

The higher the criticalness the more the handler will suffer from other handlers to be running in parallel.

Parameters

criticalness

(optional) If defined, set the criticalness to this value

Returns

The level of criticalness.

boolean Requester::Requester::fail_novar

(

boolean

fail

)

Not used any more?

Todo:

check if fail_novar() is still in use by someone, and if yes, what the hell it is used for

hashref Requester::Requester::get	(	hashref	env,
		arrayref	variables
	)

Given a list of variable names and a tester environment requests all the variables and returns the result in a hash ref.

Parameters

env	Tester environment
variables	A list of variable names.

Returns

A hash ref.

Requester::Requester Requester::Requester::get_handler

(

scalar

domain

)

Given the name of a domain this function searches for a request handler that is willing to perform requests for this domain.

If no handler has been registered yet, it tries to dynamically load one via load_module().

Parameters

domain

The name of the domain

Returns

The handler of the domain or undef if none was found.

hashref Requester::Requester::getinfo	(	arrayref	gets,
		arrayref	indexes
	)

Called by the default request() method with gets set to the list of the variables, indexes set to the list of variable indexes to be retrieved.

If gets or indexes are undefined, this means that a 'walk' through all the possible variables has to be performed.

The default behaviour is to call the getwalk() method with an empty walks list. So, a requester implementation has to implement at least one of request(), getinfo() or getwalk() in order to do something useful.

Parameters

gets	The list of names of the variables that have to be retrieved.
indexes	The list of variable indexes that have to be retrieved.

Returns

A folded hashref, at the first level the hashref uses the variable index as key, the values each point to a hashref with the name of the respective variable as a key, the scalar value as the value.

Reimplemented in Requester::SlowRequester, and Requester::expedap.

hashref Requester::Requester::getwalk	(	arrayref	gets,
		arrayref	indexes,
		arrayref	walks
	)

Similiar to getinfo(), but getwalk() is called by the default request() method if the request includes a "walk" and passes the list of variables to be walked via the walks parameter.

The default behaviour of getwalk() is to just call getinfo() with gets/indexes unset. This has been the default behaviour before getwalk() has been introduced, so getwalk() behaves the same in order to avoid breaking existing requesters. A requester implementation has to implement at least one of request(), getinfo() or getwalk() in order to do something useful.

Parameters

gets	The list of names of the variables that have to be retrieved.
indexes	The list of variable indexes that have to be retrieved.
walks	The list of variables that have to be "walked"

Returns

A folded hashref, at the first level the hashref uses the variable index as key, the values each point to a hashref with the name of the respective variable as a key, the scalar value as the value.

Reimplemented in Requester::expedap.

boolean Requester::Requester::load_module

(

scalar

module

)

Given the name of a module tries to dynamically load Requester::modulename.

Parameters

module

The name of a module

Returns

true if successful, false otherwise

Requester::Requester::new

(

)

create a requester.

Reimplemented in Requester::expedap.

protected void Requester::Requester::preexit

(

)

This function is called during program shutdown.

list Requester::Requester::probe_consumes	(	hashref	env,
		arrayref	variables
	)

Given a list of variable names and an environment, probe_consumes() will try to determine the criticalness/consumes values for the requests that it takes to get all those variable's values.

Parameters

env	Tester environment
variables	A list of variable names.

Returns

An array with two values: The first one being the criticalness, the 2nd one the consumer level of the most critical or most consuming requester that has to be called. Returns undef if no requester has to be called at all.

void Requester::Requester::register

(

list

domains

)

Register a requester for one or multiple domains.

Each Requester has to register itself under a unique domain name. Typically, a requester will create an instance of itself on load (a singleton) and register this instance via register(). This instance will then get "get" requests for the registered domains.

Parameters

domains

The list of domain names to register.

hashref Requester::Requester::request	(	hashref	env,
		scalar	domain,
		arrayref	variables
	)

Computes (or requests) the values of the variables listed in variables.

The default request() method will process the list of variables and then call getwalk() if the request includes a walk, getinfo() otherwise.

Parameters

env	Tester environment
domain	The name of the domain the request is associated with. If the requester in question is registered for one single domain only, this is always the name of the registered domain.
variables	List of variable names that are requested. Variable names starting with '@' mean that the requester is supposed to return all variables/values below this prefix.

Returns

A hashref containing the variable names associated with their values. Returns 'undef' if the requester cannot perform the request (i.e. because the variable names are unknown or the underlying system failed)

protected void Requester::Requester::set_cache	(	hashref	env,
		scalar	domain,
		scalar	name,
		hashref	value
	)

Given a domain, variable name and a value stores the value in the cache under the given domain/name.

Parameters

env	Tester environment
domain	Domain name
name	Variable name
value	Value associated with domain/name. The values being stored in the cache are required to be hash references.

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The documentation for this class was generated from the following file:

• uxmon/Requester/Requester.pm