* [bug#47897] [PATCH 1/2] publish: Add '--negative-ttl'.
[not found] <87wnsthpyn.fsf@cbaines.net>
@ 2021-05-11 13:08 ` Ludovic Courtès
2021-05-11 13:08 ` [bug#47897] [PATCH 2/2] substitutes: Reduce negative TTLs Ludovic Courtès
0 siblings, 1 reply; 2+ messages in thread
From: Ludovic Courtès @ 2021-05-11 13:08 UTC (permalink / raw)
To: 47897; +Cc: Ludovic Courtès
* guix/scripts/publish.scm (show-help, %options): Add '--negative-ttl'.
(render-narinfo, render-narinfo/cached, make-request-handler): Add #:negative-ttl
and honor it.
(run-publish-server): Add #:narinfo-negative-ttl and honor it.
(guix-publish): Honor '--negative-ttl'.
* tests/publish.scm ("negative TTL", "no negative TTL"): New tests.
---
doc/guix.texi | 10 ++++++++++
guix/scripts/publish.scm | 30 ++++++++++++++++++++++--------
tests/publish.scm | 32 +++++++++++++++++++++++++++++++-
3 files changed, 63 insertions(+), 9 deletions(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index 0947b9f028..a34b2fca1e 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -12727,6 +12727,16 @@ Additionally, when @option{--cache} is used, cached entries that have
not been accessed for @var{ttl} and that no longer have a corresponding
item in the store, may be deleted.
+@item --negative-ttl=@var{ttl}
+Similarly produce @code{Cache-Control} HTTP headers to advertise the
+time-to-live (TTL) of @emph{negative} lookups---missing store items, for
+which the HTTP 404 code is returned. By default, no negative TTL is
+advertised.
+
+This parameter can help adjust server load and substitute latency by
+instructing cooperating clients to be more or less patient when a store
+item is missing.
+
@item --cache-bypass-threshold=@var{size}
When used in conjunction with @option{--cache}, store items smaller than
@var{size} are immediately available, even when they are not yet in
diff --git a/guix/scripts/publish.scm b/guix/scripts/publish.scm
index 39bb224cad..ef6fa5f074 100644
--- a/guix/scripts/publish.scm
+++ b/guix/scripts/publish.scm
@@ -1,7 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2020 by Amar M. Singh <nly@disroot.org>
-;;; Copyright © 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
;;;
@@ -101,6 +101,8 @@ Publish ~a over HTTP.\n") %store-directory)
--workers=N use N workers to bake items"))
(display (G_ "
--ttl=TTL announce narinfos can be cached for TTL seconds"))
+ (display (G_ "
+ --negative-ttl=TTL announce missing narinfos can be cached for TTL seconds"))
(display (G_ "
--nar-path=PATH use PATH as the prefix for nar URLs"))
(display (G_ "
@@ -224,6 +226,13 @@ usage."
(leave (G_ "~a: invalid duration~%") arg))
(alist-cons 'narinfo-ttl (time-second duration)
result))))
+ (option '("negative-ttl") #t #f
+ (lambda (opt name arg result)
+ (let ((duration (string->duration arg)))
+ (unless duration
+ (leave (G_ "~a: invalid duration~%") arg))
+ (alist-cons 'narinfo-negative-ttl (time-second duration)
+ result))))
(option '("nar-path") #t #f
(lambda (opt name arg result)
(alist-cons 'nar-path arg result)))
@@ -390,14 +399,14 @@ References: ~a~%"
(define* (render-narinfo store request hash
#:key ttl (compressions (list %no-compression))
- (nar-path "nar"))
+ (nar-path "nar") negative-ttl)
"Render metadata for the store path corresponding to HASH. If TTL is true,
advertise it as the maximum validity period (in seconds) via the
'Cache-Control' header. This allows 'guix substitute' to cache it for an
appropriate duration. NAR-PATH specifies the prefix for nar URLs."
(let ((store-path (hash-part->path store hash)))
(if (string-null? store-path)
- (not-found request #:phrase "")
+ (not-found request #:phrase "" #:ttl negative-ttl)
(values `((content-type . (application/x-nix-narinfo))
,@(if ttl
`((cache-control (max-age . ,ttl)))
@@ -512,7 +521,7 @@ interpreted as the basename of a store item."
(define* (render-narinfo/cached store request hash
#:key ttl (compressions (list %no-compression))
- (nar-path "nar")
+ (nar-path "nar") negative-ttl
cache pool)
"Respond to the narinfo request for REQUEST. If the narinfo is available in
CACHE, then send it; otherwise, return 404 and \"bake\" that nar and narinfo
@@ -536,7 +545,7 @@ requested using POOL."
#:compression
(first compressions)))))
(cond ((string-null? item)
- (not-found request))
+ (not-found request #:ttl negative-ttl))
((file-exists? cached)
;; Narinfo is in cache, send it.
(values `((content-type . (application/x-nix-narinfo))
@@ -584,7 +593,7 @@ requested using POOL."
#:phrase "We're baking it"
#:ttl 300))) ;should be available within 5m
(else
- (not-found request #:phrase "")))))
+ (not-found request #:phrase "" #:ttl negative-ttl)))))
(define (compress-nar cache item compression)
"Save in directory CACHE the nar for ITEM compressed with COMPRESSION."
@@ -974,7 +983,7 @@ methods, return the applicable compression."
(define* (make-request-handler store
#:key
cache pool
- narinfo-ttl
+ narinfo-ttl narinfo-negative-ttl
(nar-path "nar")
(compressions (list %no-compression)))
(define compression-type?
@@ -1006,10 +1015,12 @@ methods, return the applicable compression."
#:cache cache
#:pool pool
#:ttl narinfo-ttl
+ #:negative-ttl narinfo-negative-ttl
#:nar-path nar-path
#:compressions compressions)
(render-narinfo store request hash
#:ttl narinfo-ttl
+ #:negative-ttl narinfo-negative-ttl
#:nar-path nar-path
#:compressions compressions)))
;; /nar/file/NAME/sha256/HASH
@@ -1068,7 +1079,7 @@ methods, return the applicable compression."
#:key
advertise? port
(compressions (list %no-compression))
- (nar-path "nar") narinfo-ttl
+ (nar-path "nar") narinfo-ttl narinfo-negative-ttl
cache pool)
(when advertise?
(let ((name (service-name)))
@@ -1084,6 +1095,7 @@ methods, return the applicable compression."
#:pool pool
#:nar-path nar-path
#:narinfo-ttl narinfo-ttl
+ #:narinfo-negative-ttl narinfo-negative-ttl
#:compressions compressions)
concurrent-http-server
`(#:socket ,socket)))
@@ -1127,6 +1139,7 @@ methods, return the applicable compression."
(user (assoc-ref opts 'user))
(port (assoc-ref opts 'port))
(ttl (assoc-ref opts 'narinfo-ttl))
+ (negative-ttl (assoc-ref opts 'narinfo-negative-ttl))
(compressions (match (filter-map (match-lambda
(('compression . compression)
compression)
@@ -1192,6 +1205,7 @@ consider using the '--user' option!~%")))
"publish worker"))
#:nar-path nar-path
#:compressions compressions
+ #:narinfo-negative-ttl negative-ttl
#:narinfo-ttl ttl))))))
;;; Local Variables:
diff --git a/tests/publish.scm b/tests/publish.scm
index 3e67c435ac..c3d086995a 100644
--- a/tests/publish.scm
+++ b/tests/publish.scm
@@ -1,7 +1,7 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2020 by Amar M. Singh <nly@disroot.org>
-;;; Copyright © 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -700,6 +700,36 @@ References: ~%"
(= (response-content-length response) (stat:size (stat log)))
(first (response-content-type response))))))
+(test-equal "negative TTL"
+ `(404 42)
+
+ (call-with-temporary-directory
+ (lambda (cache)
+ (let ((thread (with-separate-output-ports
+ (call-with-new-thread
+ (lambda ()
+ (guix-publish "--port=6786" "-C0"
+ "--negative-ttl=42s"))))))
+ (wait-until-ready 6786)
+
+ (let* ((base "http://localhost:6786/")
+ (url (string-append base (make-string 32 #\z)
+ ".narinfo"))
+ (response (http-get url)))
+ (list (response-code response)
+ (match (assq-ref (response-headers response) 'cache-control)
+ ((('max-age . ttl)) ttl)
+ (_ #f))))))))
+
+(test-equal "no negative TTL"
+ `(404 #f)
+ (let* ((uri (publish-uri
+ (string-append "/" (make-string 32 #\z)
+ ".narinfo")))
+ (response (http-get uri)))
+ (list (response-code response)
+ (assq-ref (response-headers response) 'cache-control))))
+
(test-equal "/log/NAME not found"
404
(let ((uri (publish-uri "/log/does-not-exist")))
--
2.31.1
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