diff options
Diffstat (limited to 'guix/store/deduplication.scm')
| -rw-r--r-- | guix/store/deduplication.scm | 199 |
1 files changed, 124 insertions, 75 deletions
diff --git a/guix/store/deduplication.scm b/guix/store/deduplication.scm index 0655ceb890..cd9660174c 100644 --- a/guix/store/deduplication.scm +++ b/guix/store/deduplication.scm @@ -26,45 +26,25 @@ #:use-module (guix build syscalls) #:use-module (guix base32) #:use-module (srfi srfi-11) + #:use-module (srfi srfi-34) + #:use-module (srfi srfi-35) #:use-module (rnrs io ports) #:use-module (ice-9 ftw) #:use-module (ice-9 match) #:use-module (guix serialization) #:export (nar-sha256 - deduplicate)) - -;; XXX: This port is used as a workaround on Guile <= 2.2.4 where -;; 'port-position' throws to 'out-of-range' when the offset is great than or -;; equal to 2^32: <https://bugs.gnu.org/32161>. -(define (counting-wrapper-port output-port) - "Return two values: an output port that wraps OUTPUT-PORT, and a thunk to -retrieve the number of bytes written to OUTPUT-PORT." - (let ((byte-count 0)) - (values (make-custom-binary-output-port "counting-wrapper" - (lambda (bytes offset count) - (put-bytevector output-port bytes - offset count) - (set! byte-count - (+ byte-count count)) - count) - (lambda () - byte-count) - #f - (lambda () - (close-port output-port))) - (lambda () - byte-count)))) + deduplicate + dump-file/deduplicate + copy-file/deduplicate)) (define (nar-sha256 file) "Gives the sha256 hash of a file and the size of the file in nar form." - (let*-values (((port get-hash) (open-sha256-port)) - ((wrapper get-size) (counting-wrapper-port port))) - (write-file file wrapper) - (force-output wrapper) + (let-values (((port get-hash) (open-sha256-port))) + (write-file file port) (force-output port) (let ((hash (get-hash)) - (size (get-size))) - (close-port wrapper) + (size (port-position port))) + (close-port port) (values hash size)))) (define (tempname-in directory) @@ -155,49 +135,118 @@ under STORE." (define links-directory (string-append store "/.links")) - (mkdir-p links-directory) - (let loop ((path path) - (type (stat:type (lstat path))) - (hash hash)) - (if (eq? 'directory type) - ;; Can't hardlink directories, so hardlink their atoms. - (for-each (match-lambda - ((file . properties) - (unless (member file '("." "..")) - (let* ((file (string-append path "/" file)) - (type (match (assoc-ref properties 'type) - ((or 'unknown #f) - (stat:type (lstat file))) - (type type)))) - (loop file type - (and (not (eq? 'directory type)) - (nar-sha256 file))))))) - (scandir* path)) - (let ((link-file (string-append links-directory "/" - (bytevector->nix-base32-string hash)))) - (if (file-exists? link-file) - (replace-with-link link-file path - #:swap-directory links-directory - #:store store) - (catch 'system-error - (lambda () - (link path link-file)) - (lambda args - (let ((errno (system-error-errno args))) - (cond ((= errno EEXIST) - ;; Someone else put an entry for PATH in - ;; LINKS-DIRECTORY before we could. Let's use it. - (replace-with-link path link-file - #:swap-directory - links-directory - #:store store)) - ((= errno ENOSPC) - ;; There's not enough room in the directory index for - ;; more entries in .links, but that's fine: we can - ;; just stop. - #f) - ((= errno EMLINK) - ;; PATH has reached the maximum number of links, but - ;; that's OK: we just can't deduplicate it more. - #f) - (else (apply throw args))))))))))) + (let loop ((path path) + (type (stat:type (lstat path))) + (hash hash)) + (if (eq? 'directory type) + ;; Can't hardlink directories, so hardlink their atoms. + (for-each (match-lambda + ((file . properties) + (unless (member file '("." "..")) + (let* ((file (string-append path "/" file)) + (type (match (assoc-ref properties 'type) + ((or 'unknown #f) + (stat:type (lstat file))) + (type type)))) + (loop file type + (and (not (eq? 'directory type)) + (nar-sha256 file))))))) + (scandir* path)) + (let ((link-file (string-append links-directory "/" + (bytevector->nix-base32-string hash)))) + (if (file-exists? link-file) + (replace-with-link link-file path + #:swap-directory links-directory + #:store store) + (catch 'system-error + (lambda () + (link path link-file)) + (lambda args + (let ((errno (system-error-errno args))) + (cond ((= errno EEXIST) + ;; Someone else put an entry for PATH in + ;; LINKS-DIRECTORY before we could. Let's use it. + (replace-with-link path link-file + #:swap-directory + links-directory + #:store store)) + ((= errno ENOENT) + ;; This most likely means that LINKS-DIRECTORY does + ;; not exist. Attempt to create it and try again. + (mkdir-p links-directory) + (loop path type hash)) + ((= errno ENOSPC) + ;; There's not enough room in the directory index for + ;; more entries in .links, but that's fine: we can + ;; just stop. + #f) + ((= errno EMLINK) + ;; PATH has reached the maximum number of links, but + ;; that's OK: we just can't deduplicate it more. + #f) + (else (apply throw args))))))))))) + +(define (tee input len output) + "Return a port that reads up to LEN bytes from INPUT and writes them to +OUTPUT as it goes." + (define bytes-read 0) + + (define (fail) + ;; Reached EOF before we had read LEN bytes from INPUT. + (raise (condition + (&nar-error (port input) + (file (port-filename output)))))) + + (define (read! bv start count) + ;; Read at most LEN bytes in total. + (let ((count (min count (- len bytes-read)))) + (let loop ((ret (get-bytevector-n! input bv start count))) + (cond ((eof-object? ret) + (if (= bytes-read len) + 0 ; EOF + (fail))) + ((and (zero? ret) (> count 0)) + ;; Do not return zero since zero means EOF, so try again. + (loop (get-bytevector-n! input bv start count))) + (else + (put-bytevector output bv start ret) + (set! bytes-read (+ bytes-read ret)) + ret))))) + + (make-custom-binary-input-port "tee input port" read! #f #f #f)) + +(define* (dump-file/deduplicate file input size type + #:key (store (%store-directory))) + "Write SIZE bytes read from INPUT to FILE. TYPE is a symbol, either +'regular or 'executable. + +This procedure is suitable as a #:dump-file argument to 'restore-file'. When +used that way, it deduplicates files on the fly as they are restored, thereby +removing the need to a deduplication pass that would re-read all the files +down the road." + (define hash + (call-with-output-file file + (lambda (output) + (let-values (((hash-port get-hash) + (open-hash-port (hash-algorithm sha256)))) + (write-file-tree file hash-port + #:file-type+size (lambda (_) (values type size)) + #:file-port + (const (tee input size output))) + (close-port hash-port) + (get-hash))))) + + (deduplicate file hash #:store store)) + +(define* (copy-file/deduplicate source target + #:key (store (%store-directory))) + "Like 'copy-file', but additionally deduplicate TARGET in STORE." + (call-with-input-file source + (lambda (input) + (let ((stat (stat input))) + (dump-file/deduplicate target input (stat:size stat) + (if (zero? (logand (stat:mode stat) + #o100)) + 'regular + 'executable) + #:store store))))) |