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publish: Add '--cache' and '--workers'. 

Fixes <http://bugs.gnu.org/26201>.
Reported by <dian_cecht@zoho.com>.

These options allow nars to be "baked" off-line and cached instead of
being compressed on the fly.  As a side-effect, this allows us to
provide a 'Content-Length' header for nars.

* guix/scripts/publish.scm (show-help, %options): Add '--cache' and
'--workers'.
(%default-options): Add 'workers'.
(nar-cache-file, narinfo-cache-file, run-single-baker): New procedures.
(single-baker): New macro.
(render-narinfo/cached, bake-narinfo+nar)
(render-nar/cached): New procedures.
(make-request-handler): Add #:cache and #:pool parameters and honor
them.
(run-publish-server): Likewise.
(guix-publish): Honor '--cache' and '--workers'.
* tests/publish.scm ("with cache"): New test.
* doc/guix.texi (Invoking guix publish): Document it.
This commit is contained in:
Ludovic Courtès 2017-04-17 23:13:40 +02:00
parent 339a79fd6a
commit 00753f7038
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3 changed files with 280 additions and 17 deletions
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46
doc/guix.texi
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@ -6522,6 +6522,13 @@ archive}), the daemon may download substitutes from it:
guix-daemon --substitute-urls=http://example.org:8080
@end example
By default, @command{guix publish} compresses archives on the fly as it
serves them. This ``on-the-fly'' mode is convenient in that it requires
no setup and is immediately available. However, when serving lots of
clients, we recommend using the @option{--cache} option, which enables
caching of the archives before they are sent to clients---see below for
details.
As a bonus, @command{guix publish} also serves as a content-addressed
mirror for source files referenced in @code{origin} records
(@pxref{origin Reference}). For instance, assuming @command{guix
@ -6559,10 +6566,43 @@ disable compression. The range 1 to 9 corresponds to different gzip
compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
The default is 3.
Compression occurs on the fly and the compressed streams are not
Unless @option{--cache} is used, compression occurs on the fly and
the compressed streams are not
cached. Thus, to reduce load on the machine that runs @command{guix
publish}, it may be a good idea to choose a low compression level, or to
run @command{guix publish} behind a caching proxy.
publish}, it may be a good idea to choose a low compression level, to
run @command{guix publish} behind a caching proxy, or to use
@option{--cache}. Using @option{--cache} has the advantage that it
allows @command{guix publish} to add @code{Content-Length} HTTP header
to its responses.
@item --cache=@var{directory}
@itemx -c @var{directory}
Cache archives and meta-data (@code{.narinfo} URLs) to @var{directory}
and only serve archives that are in cache.
When this option is omitted, archives and meta-data are created
on-the-fly. This can reduce the available bandwidth, especially when
compression is enabled, since this may become CPU-bound. Another
drawback of the default mode is that the length of archives is not known
in advance, so @command{guix publish} does not add a
@code{Content-Length} HTTP header to its responses, which in turn
prevents clients from knowing the amount of data being downloaded.
Conversely, when @option{--cache} is used, the first request for a store
item (@i{via} a @code{.narinfo} URL) returns 404 and triggers a
background process to @dfn{bake} the archive---computing its
@code{.narinfo} and compressing the archive, if needed. Once the
archive is cached in @var{directory}, subsequent requests succeed and
are served directly from the cache, which guarantees that clients get
the best possible bandwidth.
The ``baking'' process is performed by worker threads. By default, one
thread per CPU core is created, but this can be customized. See
@option{--workers} below.
@item --workers=@var{N}
When @option{--cache} is used, request the allocation of @var{N} worker
threads to ``bake'' archives.
@item --ttl=@var{ttl}
Produce @code{Cache-Control} HTTP headers that advertise a time-to-live

197
guix/scripts/publish.scm
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@ -24,6 +24,7 @@
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 threads)
#:use-module (rnrs bytevectors)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-2)
@ -45,13 +46,15 @@
#:use-module (guix hash)
#:use-module (guix pki)
#:use-module (guix pk-crypto)
#:use-module (guix workers)
#:use-module (guix store)
#:use-module ((guix serialization) #:select (write-file))
#:use-module (guix zlib)
#:use-module (guix ui)
#:use-module (guix scripts)
#:use-module ((guix utils) #:select (compressed-file?))
#:use-module ((guix build utils) #:select (dump-port))
#:use-module ((guix utils)
#:select (with-atomic-file-output compressed-file?))
#:use-module ((guix build utils) #:select (dump-port mkdir-p))
#:export (%public-key
%private-key
@ -69,6 +72,10 @@ Publish ~a over HTTP.\n") %store-directory)
(display (_ "
-C, --compression[=LEVEL]
compress archives at LEVEL"))
(display (_ "
-c, --cache=DIRECTORY cache published items to DIRECTORY"))
(display (_ "
--workers=N use N workers to bake items"))
(display (_ "
--ttl=TTL announce narinfos can be cached for TTL seconds"))
(display (_ "
@ -154,6 +161,13 @@ if ITEM is already compressed."
(warning (_ "zlib support is missing; \
compression disabled~%"))
result))))))
(option '(#\c "cache") #t #f
(lambda (opt name arg result)
(alist-cons 'cache arg result)))
(option '("workers") #t #f
(lambda (opt name arg result)
(alist-cons 'workers (string->number* arg)
result)))
(option '("ttl") #t #f
(lambda (opt name arg result)
(let ((duration (string->duration arg)))
@ -190,6 +204,9 @@ compression disabled~%"))
%default-gzip-compression
%no-compression))
;; Default number of workers when caching is enabled.
(workers . ,(current-processor-count))
(address . ,(make-socket-address AF_INET INADDR_ANY 0))
(repl . #f)))
@ -308,6 +325,121 @@ appropriate duration. NAR-PATH specifies the prefix for nar URLs."
#:compression compression)
<>)))))
(define* (nar-cache-file directory item
#:key (compression %no-compression))
(string-append directory "/"
(symbol->string (compression-type compression))
"/" (basename item) ".nar"))
(define* (narinfo-cache-file directory item
#:key (compression %no-compression))
(string-append directory "/"
(symbol->string (compression-type compression))
"/" (basename item)
".narinfo"))
(define run-single-baker
(let ((baking (make-weak-value-hash-table))
(mutex (make-mutex)))
(lambda (item thunk)
"Run THUNK, which is supposed to bake ITEM, but make sure only one
thread is baking ITEM at a given time."
(define selected?
(with-mutex mutex
(and (not (hash-ref baking item))
(begin
(hash-set! baking item (current-thread))
#t))))
(when selected?
(dynamic-wind
(const #t)
thunk
(lambda ()
(with-mutex mutex
(hash-remove! baking item))))))))
(define-syntax-rule (single-baker item exp ...)
"Bake ITEM by evaluating EXP, but make sure there's only one baker for ITEM
at a time."
(run-single-baker item (lambda () exp ...)))
(define* (render-narinfo/cached store request hash
#:key ttl (compression %no-compression)
(nar-path "nar")
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
requested using POOL."
(let* ((item (hash-part->path store hash))
(compression (actual-compression item compression))
(cached (and (not (string-null? item))
(narinfo-cache-file cache item
#:compression compression))))
(cond ((string-null? item)
(not-found request))
((file-exists? cached)
;; Narinfo is in cache, send it.
(values `((content-type . (application/x-nix-narinfo))
,@(if ttl
`((cache-control (max-age . ,ttl)))
'()))
(lambda (port)
(display (call-with-input-file cached
read-string)
port))))
((valid-path? store item)
;; Nothing in cache: bake the narinfo and nar in the background and
;; return 404.
(eventually pool
(single-baker item
;; (format #t "baking ~s~%" item)
(bake-narinfo+nar cache item
#:ttl ttl
#:compression compression
#:nar-path nar-path)))
(not-found request))
(else
(not-found request)))))
(define* (bake-narinfo+nar cache item
#:key ttl (compression %no-compression)
(nar-path "/nar"))
"Write the narinfo and nar for ITEM to CACHE."
(let* ((compression (actual-compression item compression))
(nar (nar-cache-file cache item
#:compression compression))
(narinfo (narinfo-cache-file cache item
#:compression compression)))
(mkdir-p (dirname nar))
(match (compression-type compression)
('gzip
;; Note: the file port gets closed along with the gzip port.
(call-with-gzip-output-port (open-output-file (string-append nar ".tmp"))
(lambda (port)
(write-file item port))
#:level (compression-level compression))
(rename-file (string-append nar ".tmp") nar))
('none
;; When compression is disabled, we retrieve files directly from the
;; store; no need to cache them.
#t))
(mkdir-p (dirname narinfo))
(with-atomic-file-output narinfo
(lambda (port)
;; Open a new connection to the store. We cannot reuse the main
;; thread's connection to the store since we would end up sending
;; stuff concurrently on the same channel.
(with-store store
(display (narinfo-string store item
(%private-key)
#:nar-path nar-path
#:compression compression)
port))))))
;; XXX: Declare the 'Guix-Compression' HTTP header, which is in fact for
;; internal consumption: it allows us to pass the compression info to
;; 'http-write', as part of the workaround to <http://bugs.gnu.org/21093>.
@ -339,6 +471,21 @@ appropriate duration. NAR-PATH specifies the prefix for nar URLs."
store-path)
(not-found request))))
(define* (render-nar/cached store cache request store-item
#:key (compression %no-compression))
"Respond to REQUEST with a nar for STORE-ITEM. If the nar is in CACHE,
return it; otherwise, return 404."
(let ((cached (nar-cache-file cache store-item
#:compression compression)))
(if (file-exists? cached)
(values `((content-type . (application/octet-stream
(charset . "ISO-8859-1"))))
;; XXX: We're not returning the actual contents, deferring
;; instead to 'http-write'. This is a hack to work around
;; <http://bugs.gnu.org/21093>.
cached)
(not-found request))))
(define (render-content-addressed-file store request
name algo hash)
"Return the content of the result of the fixed-output derivation NAME that
@ -495,6 +642,7 @@ blocking."
(define* (make-request-handler store
#:key
cache pool
narinfo-ttl
(nar-path "nar")
(compression %no-compression))
@ -515,10 +663,17 @@ blocking."
(((= extract-narinfo-hash (? string? hash)))
;; TODO: Register roots for HASH that will somehow remain for
;; NARINFO-TTL.
(render-narinfo store request hash
#:ttl narinfo-ttl
#:nar-path nar-path
#:compression compression))
(if cache
(render-narinfo/cached store request hash
#:cache cache
#:pool pool
#:ttl narinfo-ttl
#:nar-path nar-path
#:compression compression)
(render-narinfo store request hash
#:ttl narinfo-ttl
#:nar-path nar-path
#:compression compression)))
;; /nar/file/NAME/sha256/HASH
(("file" name "sha256" hash)
(guard (c ((invalid-base32-character? c)
@ -534,13 +689,16 @@ blocking."
;; /nar/gzip/<store-item>
((components ... "gzip" store-item)
(if (and (nar-path? components) (zlib-available?))
(render-nar store request store-item
#:compression
(match compression
(($ <compression> 'gzip)
compression)
(_
%default-gzip-compression)))
(let ((compression (match compression
(($ <compression> 'gzip)
compression)
(_
%default-gzip-compression))))
(if cache
(render-nar/cached store cache request store-item
#:compression compression)
(render-nar store request store-item
#:compression compression)))
(not-found request)))
;; /nar/<store-item>
@ -555,8 +713,11 @@ blocking."
(define* (run-publish-server socket store
#:key (compression %no-compression)
(nar-path "nar") narinfo-ttl)
(nar-path "nar") narinfo-ttl
cache pool)
(run-server (make-request-handler store
#:cache cache
#:pool pool
#:nar-path nar-path
#:narinfo-ttl narinfo-ttl
#:compression compression)
@ -606,6 +767,8 @@ blocking."
(socket (open-server-socket address))
(nar-path (assoc-ref opts 'nar-path))
(repl-port (assoc-ref opts 'repl))
(cache (assoc-ref opts 'cache))
(workers (assoc-ref opts 'workers))
;; Read the key right away so that (1) we fail early on if we can't
;; access them, and (2) we can then drop privileges.
@ -631,6 +794,12 @@ consider using the '--user' option!~%")))
(repl:spawn-server (repl:make-tcp-server-socket #:port repl-port)))
(with-store store
(run-publish-server socket store
#:cache cache
#:pool (and cache (make-pool workers))
#:nar-path nar-path
#:compression compression
#:narinfo-ttl ttl))))))
;;; Local Variables:
;;; eval: (put 'single-baker 'scheme-indent-function 1)
;;; End:

54
tests/publish.scm
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@ -314,4 +314,58 @@ References: ~%"
(call-with-input-string "" port-sha256))))))
(response-code (http-get uri))))
(unless (zlib-available?)
(test-skip 1))
(test-equal "with cache"
(list #t
`(("StorePath" . ,%item)
("URL" . ,(string-append "nar/gzip/" (basename %item)))
("Compression" . "gzip"))
200 ;nar/gzip/…
#t ;Content-Length
200) ;nar/…
(call-with-temporary-directory
(lambda (cache)
(define (wait-for-file file)
(let loop ((i 20))
(or (file-exists? file)
(begin
(pk 'wait-for-file file)
(sleep 1)
(loop (- i 1))))))
(let ((thread (with-separate-output-ports
(call-with-new-thread
(lambda ()
(guix-publish "--port=6797" "-C2"
(string-append "--cache=" cache)))))))
(wait-until-ready 6797)
(let* ((base "http://localhost:6797/")
(part (store-path-hash-part %item))
(url (string-append base part ".narinfo"))
(nar-url (string-append base "/nar/gzip/" (basename %item)))
(cached (string-append cache "/gzip/" (basename %item)
".narinfo"))
(nar (string-append cache "/gzip/"
(basename %item) ".nar"))
(response (http-get url)))
(and (= 404 (response-code response))
(wait-for-file cached)
(let ((body (http-get-port url))
(compressed (http-get nar-url))
(uncompressed (http-get (string-append base "nar/"
(basename %item)))))
(list (file-exists? nar)
(filter (lambda (item)
(match item
(("Compression" . _) #t)
(("StorePath" . _) #t)
(("URL" . _) #t)
(_ #f)))
(recutils->alist body))
(response-code compressed)
(= (response-content-length compressed)
(stat:size (stat nar)))
(response-code uncompressed)))))))))
(test-end "publish")