- (let ([etag (header-get headers #"ETag")]
- [lmod (header-get headers #"Last-Modified")])
- (if (and etag
- (file-exists? cached-etag-path)
- (bytes=? etag (file->bytes cached-etag-path)))
- (log-info "ETags match, skipping the rest of ~v" (url->string u))
- (begin
- (log-info
- "Downloading the rest of ~v. ETag: ~a, Last-Modified: ~v"
- (url->string u) etag lmod)
- (make-parent-directory* cached-object-path)
- (make-parent-directory* cached-etag-path)
- (make-parent-directory* cached-lmod-path)
- (call-with-output-file cached-object-path
- (curry copy-port body-input)
- #:exists 'replace)
- (when etag
- (display-to-file etag cached-etag-path #:exists 'replace))
- (when lmod
- (display-to-file etag cached-lmod-path #:exists 'replace))))
+ (let* ([etag (header-get headers #"ETag")]
+ [lmod (header-get headers #"Last-Modified")]
+ [lmod-curr (if lmod (rfc2822->epoch lmod) #f)]
+ [lmod-prev (if (file-exists? cached-lmod-path)
+ (rfc2822->epoch (file->bytes cached-lmod-path))
+ #f)])
+ (log-debug "lmod-curr:~v lmod-prev:~v" lmod-curr lmod-prev)
+ (unless (or (and etag
+ (file-exists? cached-etag-path)
+ (bytes=? etag (file->bytes cached-etag-path))
+ (begin
+ (log-info "ETags match, skipping the rest of ~v" (url->string u))
+ #t))
+ (and lmod-curr
+ lmod-prev
+ (<= lmod-curr lmod-prev)
+ (begin
+ (log-info "Last-Modified <= current skipping the rest of ~v" (url->string u))
+ #t)))
+ (begin
+ (log-info
+ "Downloading the rest of ~v. ETag: ~a, Last-Modified: ~v"
+ (url->string u) etag lmod)
+ (make-parent-directory* cached-object-path)
+ (make-parent-directory* cached-etag-path)
+ (make-parent-directory* cached-lmod-path)
+ (call-with-output-file cached-object-path
+ (curry copy-port body-input)
+ #:exists 'replace)
+ (when etag
+ (display-to-file etag cached-etag-path #:exists 'replace))
+ (when lmod
+ (display-to-file lmod cached-lmod-path #:exists 'replace))))