88 lines
2.5 KiB
Racket
88 lines
2.5 KiB
Racket
#lang racket/base
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(require (planet ryanc/db)
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(prefix-in whalesong: "../version.rkt")
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racket/file
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racket/path
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file/md5)
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(define cache-directory-path
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(build-path (find-system-path 'pref-dir)
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"whalesong"))
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;; create-cache-directory!: -> void
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(define (create-cache-directory!)
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(unless (directory-exists? cache-directory-path)
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(make-directory* cache-directory-path)))
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(define (ensure-cache-db-structure!)
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(when (not (file-exists? whalesong-cache.sqlite3))
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;; Clear existing cache files: they're obsolete.
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(for ([file (directory-list cache-directory-path)])
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(when (file-exists? (build-path cache-directory-path file))
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(with-handlers ([exn:fail? void])
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(delete-file (build-path cache-directory-path file)))))
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(define conn
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(sqlite3-connect #:database whalesong-cache.sqlite3
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#:mode 'create))
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(query-exec conn
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(string-append
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"create table cache(path string not null primary key, "
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" md5sum string not null, "
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"data blob not null);"))
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(query-exec conn
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"CREATE INDEX cache_md5sum_idx ON cache (md5sum);")
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(disconnect conn)))
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(define whalesong-cache.sqlite3
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(build-path cache-directory-path
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(format "whalesong-cache-~a.sqlite"
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whalesong:version)))
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(create-cache-directory!)
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(ensure-cache-db-structure!)
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(define conn
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(sqlite3-connect #:database whalesong-cache.sqlite3))
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(define lookup-cache-stmt
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(prepare conn (string-append "select path, md5sum, data "
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"from cache "
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"where path=? and md5sum=?")))
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(define insert-cache-stmt
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(prepare conn (string-append "insert into cache(path, md5sum, data)"
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" values (?, ?, ?);")))
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;; cached?:
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(define (cached? path)
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(cond
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[(file-exists? path)
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(query-maybe-row conn
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lookup-cache-stmt
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(path->string path)
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(call-with-input-file* path md5))]
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[else
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#f]))
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;; save-in-cache!: path string -> void
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;; Saves a record.
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(define (save-in-cache! path data)
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(cond
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[(file-exists? path)
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(query-exec conn
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insert-cache-stmt
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(path->string path)
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(call-with-input-file* path md5)
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data)]
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[else
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(error 'save-in-cache! "File ~e does not exist" path)])) |