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substitute-binary: Pipeline HTTP requests instead of using threads.

* guix/scripts/substitute-binary.scm (fetch-narinfo, %lookup-threads,
  n-par-map*): Remove.
  (narinfo-cache-file, cached-narinfo, cache-narinfo!, narinfo-request,
  http-multiple-get, read-to-eof, fetch-narinfos, lookup-narinfos,
  narinfo-from-file): New procedures.
  (lookup-narinfo): Rewrite in terms of 'lookup-narinfos'.
  (guix-substitute-binary): Use 'lookup-narinfos' instead of
  'lookup-narinfo'.
This commit is contained in:
Ludovic Courtès 2015-03-23 22:25:04 +01:00
parent 0561e9ae16
commit d3a652037e

View file

@ -28,7 +28,7 @@
#:use-module (guix base64)
#:use-module (guix pk-crypto)
#:use-module (guix pki)
#:use-module ((guix build utils) #:select (mkdir-p))
#:use-module ((guix build utils) #:select (mkdir-p dump-port))
#:use-module ((guix build download)
#:select (progress-proc uri-abbreviation))
#:use-module (ice-9 rdelim)
@ -48,6 +48,8 @@
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (web uri)
#:use-module (web request)
#:use-module (web response)
#:use-module (guix http-client)
#:export (narinfo-signature->canonical-sexp
read-narinfo
@ -218,7 +220,7 @@ failure."
gonna have to wait."
(delay (begin
(format (current-error-port)
(_ "updating list of substitutes from '~a'...~%")
(_ "updating list of substitutes from '~a'...\r")
url)
(open-cache url))))
@ -380,40 +382,56 @@ or is signed by an unauthorized key."
the cache STR originates form."
(call-with-input-string str (cut read-narinfo <> cache-uri)))
(define (fetch-narinfo cache path)
"Return the <narinfo> record for PATH, or #f if CACHE does not hold PATH."
(define (download url)
;; Download the .narinfo from URL, and return its contents as a list of
;; key/value pairs. Don't emit an error message upon 404.
(false-if-exception (fetch (string->uri url)
#:quiet-404? #t)))
(and (string=? (cache-store-directory cache) (%store-prefix))
(and=> (download (string-append (cache-url cache) "/"
(store-path-hash-part path)
".narinfo"))
(cute read-narinfo <> (cache-url cache)))))
(define (obsolete? date now ttl)
"Return #t if DATE is obsolete compared to NOW + TTL seconds."
(time>? (subtract-duration now (make-time time-duration 0 ttl))
(make-time time-monotonic 0 date)))
(define %lookup-threads
;; Number of threads spawned to perform lookup operations. This means we
;; can have this many simultaneous HTTP GET requests to the server, which
;; limits the impact of connection latency.
20)
(define (lookup-narinfo cache path)
"Check locally if we have valid info about PATH, otherwise go to CACHE and
check what it has."
(define (narinfo-cache-file path)
"Return the name of the local file that contains an entry for PATH."
(string-append %narinfo-cache-directory "/"
(store-path-hash-part path)))
(define (cached-narinfo path)
"Check locally if we have valid info about PATH. Return two values: a
Boolean indicating whether we have valid cached info, and that info, which may
be either #f (when PATH is unavailable) or the narinfo for PATH."
(define now
(current-time time-monotonic))
(define cache-file
(string-append %narinfo-cache-directory "/"
(store-path-hash-part path)))
(narinfo-cache-file path))
(catch 'system-error
(lambda ()
(call-with-input-file cache-file
(lambda (p)
(match (read p)
(('narinfo ('version 1)
('cache-uri cache-uri)
('date date) ('value #f))
;; A cached negative lookup.
(if (obsolete? date now %narinfo-negative-ttl)
(values #f #f)
(values #t #f)))
(('narinfo ('version 1)
('cache-uri cache-uri)
('date date) ('value value))
;; A cached positive lookup
(if (obsolete? date now %narinfo-ttl)
(values #f #f)
(values #t (string->narinfo value cache-uri))))
(('narinfo ('version v) _ ...)
(values #f #f))))))
(lambda _
(values #f #f))))
(define (cache-narinfo! cache path narinfo)
"Cache locally NARNIFO for PATH, which originates from CACHE. NARINFO may
be #f, in which case it indicates that PATH is unavailable at CACHE."
(define now
(current-time time-monotonic))
(define (cache-entry cache-uri narinfo)
`(narinfo (version 1)
@ -421,43 +439,153 @@ check what it has."
(date ,(time-second now))
(value ,(and=> narinfo narinfo->string))))
(let*-values (((valid? cached)
(catch 'system-error
(lambda ()
(call-with-input-file cache-file
(lambda (p)
(match (read p)
(('narinfo ('version 1)
('cache-uri cache-uri)
('date date) ('value #f))
;; A cached negative lookup.
(if (obsolete? date now %narinfo-negative-ttl)
(values #f #f)
(values #t #f)))
(('narinfo ('version 1)
('cache-uri cache-uri)
('date date) ('value value))
;; A cached positive lookup
(if (obsolete? date now %narinfo-ttl)
(values #f #f)
(values #t (string->narinfo value
cache-uri))))
(('narinfo ('version v) _ ...)
(values #f #f))))))
(lambda _
(values #f #f)))))
(if valid?
cached ; including negative caches
(with-atomic-file-output (narinfo-cache-file path)
(lambda (out)
(write (cache-entry (cache-url cache) narinfo) out)))
narinfo)
(define (narinfo-request cache-url path)
"Return an HTTP request for the narinfo of PATH at CACHE-URL."
(let ((url (string-append cache-url "/" (store-path-hash-part path)
".narinfo")))
(build-request (string->uri url) #:method 'GET)))
(define (http-multiple-get base-url requests proc)
"Send all of REQUESTS to the server at BASE-URL. Call PROC for each
response, passing it the request object, the response, and a port from which
to read the response body. Return the list of results."
(let connect ((requests requests)
(result '()))
;; (format (current-error-port) "connecting (~a requests left)..."
;; (length requests))
(let ((p (open-socket-for-uri base-url)))
;; Send all of REQUESTS in a row.
(setvbuf p _IOFBF (expt 2 16))
(for-each (cut write-request <> p) requests)
(force-output p)
;; Now start processing responses.
(let loop ((requests requests)
(result result))
(match requests
(()
(reverse result))
((head tail ...)
(let* ((resp (read-response p))
(body (response-body-port resp)))
;; The server can choose to stop responding at any time, in which
;; case we have to try again. Check whether that is the case.
(match (assq 'connection (response-headers resp))
(('connection 'close)
(connect requests result)) ;try again
(_
(loop tail ;keep going
(cons (proc head resp body) result)))))))))))
(define (read-to-eof port)
"Read from PORT until EOF is reached. The data are discarded."
(dump-port port (%make-void-port "w")))
(define (narinfo-from-file file url)
"Attempt to read a narinfo from FILE, using URL as the cache URL. Return #f
if file doesn't exist, and the narinfo otherwise."
(catch 'system-error
(lambda ()
(call-with-input-file file
(cut read-narinfo <> url)))
(lambda args
(if (= ENOENT (system-error-errno args))
#f
(apply throw args)))))
(define (fetch-narinfos cache paths)
"Retrieve all the narinfos for PATHS from CACHE and return them."
(define url
(cache-url cache))
(define update-progress!
(let ((done 0))
(lambda ()
(display #\cr (current-error-port))
(force-output (current-error-port))
(format (current-error-port)
(_ "updating list of substitutes from '~a'... ~5,1f%")
url (* 100. (/ done (length paths))))
(set! done (+ 1 done)))))
(define (handle-narinfo-response request response port)
(let ((len (response-content-length response)))
;; Make sure to read no more than LEN bytes since subsequent bytes may
;; belong to the next response.
(case (response-code response)
((200) ; hit
(let ((narinfo (read-narinfo port url #:size len)))
(cache-narinfo! cache (narinfo-path narinfo) narinfo)
(update-progress!)
narinfo))
((404) ; failure
(let* ((path (uri-path (request-uri request)))
(hash-part (string-drop-right path 8))) ; drop ".narinfo"
(if len
(get-bytevector-n port len)
(read-to-eof port))
(cache-narinfo! cache
(find (cut string-contains <> hash-part) paths)
#f)
(update-progress!))
#f)
(else ; transient failure
(if len
(get-bytevector-n port len)
(read-to-eof port))
#f))))
(and (string=? (cache-store-directory cache) (%store-prefix))
(let ((uri (string->uri url)))
(case (and=> uri uri-scheme)
((http)
(let ((requests (map (cut narinfo-request url <>) paths)))
(update-progress!)
(let ((result (http-multiple-get url requests
handle-narinfo-response)))
(newline (current-error-port))
result)))
((file #f)
(let* ((base (string-append (uri-path uri) "/"))
(files (map (compose (cut string-append base <> ".narinfo")
store-path-hash-part)
paths)))
(filter-map (cut narinfo-from-file <> url) files)))
(else
(leave (_ "~s: unsupported server URI scheme~%")
(if uri (uri-scheme uri) url)))))))
(define (lookup-narinfos cache paths)
"Return the narinfos for PATHS, invoking the server at CACHE when no
information is available locally."
(let-values (((cached missing)
(fold2 (lambda (path cached missing)
(let-values (((valid? value)
(cached-narinfo path)))
(if valid?
(values (cons value cached) missing)
(values cached (cons path missing)))))
'()
'()
paths)))
(if (null? missing)
cached
(let* ((cache (force cache))
(narinfo (and cache (fetch-narinfo cache path))))
;; Cache NARINFO only when CACHE was actually accessible. This
;; avoids caching negative hits when in fact we just lacked network
;; access.
(when cache
(with-atomic-file-output cache-file
(lambda (out)
(write (cache-entry (cache-url cache) narinfo) out))))
narinfo))))
(missing (if cache
(fetch-narinfos cache missing)
'())))
(append cached missing)))))
(define (lookup-narinfo cache path)
"Return the narinfo for PATH in CACHE, or #f when no substitute for PATH was
found."
(match (lookup-narinfos cache (list path))
((answer) answer)))
(define (remove-expired-cached-narinfos)
"Remove expired narinfo entries from the cache. The sole purpose of this
@ -580,16 +708,6 @@ Internal tool to substitute a pre-built binary to a local build.\n"))
;;; Entry point.
;;;
(define n-par-map*
;; We want the ability to run many threads in parallel, regardless of the
;; number of cores. However, Guile 2.0.5 has a bug whereby 'n-par-map' ends
;; up consuming a lot of memory, possibly leading to death. Thus, resort to
;; 'par-map' on 2.0.5.
(if (guile-version>? "2.0.5")
n-par-map
(lambda (n proc lst)
(par-map proc lst))))
(define (check-acl-initialized)
"Warn if the ACL is uninitialized."
(define (singleton? acl)
@ -698,9 +816,7 @@ substituter disabled~%")
;; Return the subset of PATHS available in CACHE.
(let ((substitutable
(if cache
(n-par-map* %lookup-threads
(cut lookup-narinfo cache <>)
paths)
(lookup-narinfos cache paths)
'())))
(for-each (lambda (narinfo)
(format #t "~a~%" (narinfo-path narinfo)))
@ -710,9 +826,7 @@ substituter disabled~%")
;; Reply info about PATHS if it's in CACHE.
(let ((substitutable
(if cache
(n-par-map* %lookup-threads
(cut lookup-narinfo cache <>)
paths)
(lookup-narinfos cache paths)
'())))
(for-each (lambda (narinfo)
(format #t "~a\n~a\n~a\n"