thin-provisioning-tools/functional-tests/block-cache.scm
Joe Thornber 7f7a7d6605 [functional tests] start thinking about a block cache interface.
I want to use FFI to link with a C library containing the actual block
cache, io engine and crc32 code.
2017-08-14 10:05:38 +01:00

84 lines
2.0 KiB
Scheme

(library
(block-cache)
(exports)
(imports (chezscheme))
(define (cache-open path block-size nr-cache-blocks)
...
)
(define (cache-read-lock cache index)
)
(define (cache-write-lock cache index))
(define (cache-zero-lock cache index))
;; The super block is the one that should be written last. Unlocking this
;; block triggers the following events:
;;
;; i) synchronous write of all dirty blocks _except_ the superblock.
;;
;; ii) synchronous write of superblock
;;
;; If any locks are held at the time of the superblock being unlocked then an
;; error will be raised.
(define (cache-superblock-lock cache index))
(define (cache-superblock-zero))
(define (cache-unlock b)
)
(define-syntax with-block
(syntax-rules ()
((_ (var b) body ...)
(let ((var b))
(dynamic-wind
(lambda () #f)
(lambda () body ...)
(lambda () (block-put var)))))))
;;--------------------------------------------
(define-record-type ro-spine (fields cache parent child))
(define (ro-spine-begin cache)
(make-ro-spine cache #f #f))
(define (ro-spine-end spine)
(define (unlock bl)
(if bl (cache-unlock) #f))
(unlock (ro-spine-parent spine))
(unlock (ro-spine-child spine))
(ro-spine-parent-set! spine #f)
(ro-spind-child-set! spine #f))
(define (ro-spine-step spine index)
(define (push b)
(cond
((ro-spine-child spine)
(let ((grandparent (ro-spine-parent spine)))
(ro-spine-parent-set! spine (ro-spine-child spine))
(ro-spine-child-set! spine b)))
((ro-spine-parent spine)
(ro-spine-child-set! spine b))
(else
(ro-spine-parent-set! spine b))))
(push (cache-read-lock (ro-spine-cache spine) index)))
(define-syntax with-ro-spine
(syntax-rules ()
((_ (n cache) body ...)
(let ((n (ro-spine-begin cache)))
(dynamic-wind
(lambda () #f)
(lambda () body ...)
(lambda () (ro-spine-end)))))))
)