make_suspension(+Goal, +Prio, -Susp)

Goal

A Prolog Goal.

Prio

A small integer.

Susp

A variable.

Description

A suspension can be in three states:

	State		Printed as
	---------------------------------
	sleeping	'SUSP-_123-susp'
	scheduled	'SUSP-_123-sched'
	dead		'SUSP-_123-dead'

The Prio argument determines the priority with which the Goal will be scheduled when woken. It can be a positive number between 1 and 12, or zero, in which case the priority defaults to the priority setting of the predicate which is called in Goal.

Note that a suspension is not a standard Prolog data structure and can only be manipulated in a restricted way. In particular, a suspension is not an atom although it gets printed by default in the form 'SUSP-_123-susp'. The only way to create a suspension is with make_suspension/3,4, suspend/3,4 or by copying an existing suspension. The contents of a suspension can only be retrieved using get_suspension_data/3.

Modes and Determinism

• make_suspension(+, +, -) is det

Modules

Exceptions

(4) instantiation fault

Goal is not instantiated.

(5) type error

Goal is not a callable term.

(5) type error

Susp is not a variable.

(5) type error

Prio is not an integer.

(6) out of range

Prio is not a valid priority.

(60) referring to an undefined procedure

Goal refers to an undefined precedure.

Examples

[eclipse 1]: make_suspension(writeln(hello), 1, S), suspensions(Ss).

S = 'SUSP-_264-susp'
Ss = ['SUSP-_264-susp']

Delayed goals:
	writeln(hello)
Yes (0.00s cpu)


[eclipse 2]: make_suspension(true, 3, S), is_suspension(S), type_of(S,T).

S = 'SUSP-_272-susp'
T = goal


Delayed goals:
        true
Yes (0.00s cpu)

See Also