Provides an abstraction for a managed object, known as a resource, with a fixed lifetime. This might be used to create a file port that will automatically close if unused for some amount of time.
- make-timed-resource OPENER CLOSER TIMEOUT #!optional NAMEprocedure
Returns a new timed-resource object that covers a resource with a lifetime of TIMEOUT seconds. The resource is acquired by the OPENER and released by the CLOSER. The acquired resource will be released automatically at the end of its' life.
During shutdown returns #f.
- (procedure () *) ; returns the resource-object
- (procedure (*)) ; takes the resource-object (returned by OPENER)
- number ; seconds
- * ; prefix for the gensym of the created timed-resource
No attempt is made to serialize access to a resource, this is up to the caller; just don't share the thing.
Exceptions occurring during resource acquisition or release abort the operation. Exceptions during resource release at shutdown are just displayed but no further action is taken.
- call-with-timed-resource TIMED-RESOURCE ACTIONprocedure
Returns the result of invoking ACTION with the resource covered by the TIMED-RESOURCE. The acquired resource will not be released during the extent of the call-with-timed-resource invocation.
- (<(timed-resource-open) cached> -> *) ; protected use of resource.
- (use-timed-resource (TIMED-RESOURCE VAR) BODY ...) -> *syntax
Returns the result of invoking BODY ... with the resource covered by the TIMED-RESOURCE. The acquired resource will be bound to VAR in the BODY .... The acquired resource will not be released during the extent of the use-timed-resource invocation.
- timed-resource? OBJECTprocedure
Is the OBJECT a timed-resource?
- timed-resource-open? TIMED-RESOURCEprocedure
Returns unique id for TIMED-RESOURCE.
- timed-resource-name TIMED-RESOURCEprocedure
Returns unique id for TIMED-RESOURCE.
- default-timed-resource-timeout SECONDSprocedure
Gets & sets the number of seconds to wait for a thread to quit.
Default is #f.
Currently only used at shutdown.
(import scheme (srfi-4) timed-resource) ;; Returns a blob from port. (define (read-blob u8cnt #!optional (port (current-input-port))) (u8vector->blob (read-u8vector u8cnt port)) ) ;; Returns a blob of random bits. ;; random device (*nix only) ;; ;; ((random-blob [SEC]) [CNT]) ;; SEC - the number of seconds, default is 5.0 ;; CNT - the number of random bytes, default is 16 (define (random-blob #!optional (lifetime 5.0)) (let ((+tr+ (make-timed-resource (cut open-input-file "/dev/random" #:binary) (cut close-output-port <>) lifetime)) ) (lambda (#!optional (cnt 16)) (print "\t** open? " (timed-resource-open? +tr+) " **") (use-timed-resource (+tr+ ip) (read-blob cnt ip)) ) ) )
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- Remove deperecated with-timed-resource.
- Fix egg category.
- Add timed-resource-open?.
- Fix make-timed-resource return.
- C5 port.
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