Add build-pages function

Dr-Nekoma · Jan 13, 2024 · 9c7535c · 9c7535c
1 parent 7914de1
commit 9c7535c
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Showing 2 changed files with 81 additions and 20 deletions.
diff --git a/main.rkt b/main.rkt
@@ -6,7 +6,9 @@
   (submod RacketowerDB/io reader)
   ;(submod RacketowerDB/language parser)
   (submod RacketowerDB/backend server)
-  RacketowerDB/util)
+  RacketowerDB/bplustree
+  RacketowerDB/util
+  RacketowerDB/pagination)
 
 ;; review if this is needed for eval-syntax
 (dynamic-require 'RacketowerDB/ast 0)
@@ -90,21 +92,25 @@
     `(("MODEL" . ,(stringl "Abc"))
       ("YEAR" . ,(integer32 2013))))
 
-  (check-local-constraints programmer-table (list row1 row2))
-  (hash-set! schema "CAR" car-table)
-  (hash-set! schema "TEST" procedure-test)
   (hash-set! schema "PROGRAMMER" programmer-table)
-  (write-schema-to-disk schema)
-  (set! schema (read-schema-from-disk "schema"))
-  (check-local-constraints (hash-ref schema "PROGRAMMER") (list row1 row2))
-  (println schema)
   (set! schema (write-rows-to-disk schema "PROGRAMMER" (list row1 row2)))
-  (println (read-table-values-from-disk schema "PROGRAMMER"))
-  (write-table-to-disk programmer-table "PROGRAMMER")
-  (let ((read-table (read-table-from-disk "PROGRAMMER")))
-    (hash-set! schema "PROGRAMMER" read-table)
-    (set! schema (write-rows-to-disk schema "PROGRAMMER" (list row1 row2)))
-    (println schema)))
+  ;; (println (read-table-values-from-disk schema "PROGRAMMER"))
+  (define-values (pages amount-already-read) (build-pages 0 1 1 (+ 7 10 4) 0 "AGE" schema "PROGRAMMER"))
+  (println pages)
+  (println amount-already-read)
+  ;; (check-local-constraints programmer-table (list row1 row2))
+  ;; (hash-set! schema "CAR" car-table)
+  ;; (hash-set! schema "TEST" procedure-test)
+  ;; (write-schema-to-disk schema)
+  ;; (set! schema (read-schema-from-disk "schema"))
+  ;; (check-local-constraints (hash-ref schema "PROGRAMMER") (list row1 row2))
+  ;; (println schema)
+  ;; (write-table-to-disk programmer-table "PROGRAMMER")
+  ;; (let ((read-table (read-table-from-disk "PROGRAMMER")))
+  ;;   (hash-set! schema "PROGRAMMER" read-table)
+  ;;   (set! schema (write-rows-to-disk schema "PROGRAMMER" (list row1 row2)))
+  ;;   (println schema))
+  (tree-test))
 
   ;;(exit-handler)
   ;;(server-entrypoint)

diff --git a/pagination.rkt b/pagination.rkt
@@ -2,19 +2,74 @@
 
 (require
  ffi/unsafe
- (only-in RacketowerDB/util checked-guard))
+ (only-in RacketowerDB/util checked-guard build-ndf-filename)
+ (submod RacketowerDB/io reader)
+ RacketowerDB/ast)
+
+(provide build-pages)
 
 (struct page [instances indexes] #:transparent
   #:guard
   (checked-guard
-   [(instances . (vectorof bytes?))
-    (indexes . (vectorof (cons/c exact-nonnegative-integer? exact-nonnegative-integer?)))]
+   [(instances . (listof (listof byte?)))
+    (indexes . (listof (cons/c exact-nonnegative-integer? exact-nonnegative-integer?)))]
    (values instances indexes)))
 
-(struct pager [pages tree amount-read] #:transparent
+(struct pager [pages tree amount-read instancesPerPage maxPagesAtOnce] #:transparent
   #:guard
   (checked-guard
-   [(pages . (vectorof page?))
+   [(pages . (listof page?))
     (tree .  cpointer?)
-    (amount-read . exact-nonnegative-integer?)]
+    (amount-read . exact-nonnegative-integer?)
+    (instancesPerPage . exact-nonnegative-integer?)
+    (maxPagesAtOnce . exact-nonnegative-integer?)]
    (values pages tree amount-read)))
+
+(define (split-by lst n)
+   (if (not (empty? lst))
+       (cons (take lst n) (split-by (drop lst n) n))
+       '()))
+
+(define (build-pages
+         initial-page-number
+         instances-per-page
+         page-bound
+         instance-size
+         amount-already-read
+         attribute-to-index
+         schema
+         entity-name)
+  ;; TODO: Leave an error message to only work on the supported types.
+  (define (query data attribute-to-index)
+    (first (map (lambda [row] (integer32-value (hash-ref row attribute-to-index))) data)))
+  (define (create-indexes instances schema entity-name attribute-to-index)
+    (map (lambda (index instance)
+           (let* [(instance-bytes (list->bytes instance))
+                  (read-content (read-table-values-from-disk schema entity-name #:source instance-bytes))
+                  (attempt-to-find (query read-content attribute-to-index))]
+             ;; TODO: We are missing some error checking in here
+             (cons attempt-to-find index)))
+         (range (length instances))
+         instances))
+  (define file-name (build-ndf-filename entity-name #:data? 'data))
+  (define content-length (file-size file-name))
+  (let loop [(amount-already-read amount-already-read)
+             (reader (open-input-file file-name #:mode 'binary))
+             (index initial-page-number)
+             (pages (list))]
+    (if (equal? index page-bound)
+        (values pages amount-already-read)
+        (begin
+          (file-position reader (* index instance-size))
+          (let* [(amount-to-read (if (> (* instances-per-page instance-size) (- content-length amount-already-read))
+                                     (- content-length amount-already-read)
+                                     (* instances-per-page instance-size)))
+                 (buffer (bytes->list (read-bytes amount-to-read reader)))
+                 (instances (take (split-by buffer instance-size) page-bound))
+                 (indexes (create-indexes instances schema entity-name attribute-to-index))]
+            (loop
+             (+ amount-already-read amount-to-read)
+             reader
+             (+ instances-per-page index)
+             (append pages (list (page instances indexes)))))))))
+