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substitute: Cache and reuse connections while substituting. 

That way, when fetching a series of substitutes from the same server(s),
the connection is reused instead of being closed/opened for each
substitutes, which saves on network round trips and TLS handshakes.

* guix/http-client.scm (http-fetch): Add #:keep-alive? and honor it.
* guix/progress.scm (progress-report-port): Add #:close? parameter and
honor it.
* guix/scripts/substitute.scm (at-most): Return the tail as a second
value.
(fetch): Add #:port and #:keep-alive? and honor them.
(%max-cached-connections): New variable.
(open-connection-for-uri/cached, call-with-cached-connection): New
procedures.
(with-cached-connection): New macro.
(process-substitution): Wrap 'fetch' call in 'with-cached-connection'.
Pass #:close? to 'progress-report-port'.
master
Ludovic Courtès 2020-12-02 22:49:39 +01:00
parent 711df9ef3c
commit 5ff521452b
No known key found for this signature in database
GPG Key ID: 090B11993D9AEBB5
4 changed files with 116 additions and 34 deletions
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12
guix/http-client.scm
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@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2020 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2012, 2015 Free Software Foundation, Inc.
;;; Copyright © 2017 Tobias Geerinckx-Rice <me@tobias.gr>
@ -70,6 +70,7 @@
(define* (http-fetch uri #:key port (text? #f) (buffered? #t)
(keep-alive? #f)
(verify-certificate? #t)
(headers '((user-agent . "GNU Guile")))
timeout)
@ -79,6 +80,9 @@ textual. Follow any HTTP redirection. When BUFFERED? is #f, return an
unbuffered port, suitable for use in `filtered-port'. HEADERS is an alist of
extra HTTP headers.
When KEEP-ALIVE? is true, the connection is marked as 'keep-alive' and PORT is
not closed upon completion.
When VERIFY-CERTIFICATE? is true, verify HTTPS server certificates.
TIMEOUT specifies the timeout in seconds for connection establishment; when
@ -104,11 +108,7 @@ Raise an '&http-get-error' condition if downloading fails."
(setvbuf port 'none))
(let*-values (((resp data)
(http-get uri #:streaming? #t #:port port
;; XXX: When #:keep-alive? is true, if DATA is
;; a chunked-encoding port, closing DATA won't
;; close PORT, leading to a file descriptor
;; leak.
#:keep-alive? #f
#:keep-alive? keep-alive?
#:headers headers))
((code)
(response-code resp)))

8
guix/progress.scm
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@ -337,9 +337,10 @@ should be a <progress-reporter> object."
(report total)
(loop total (get-bytevector-n! in buffer 0 buffer-size))))))))
(define (progress-report-port reporter port)
(define* (progress-report-port reporter port #:key (close? #t))
"Return a port that continuously reports the bytes read from PORT using
REPORTER, which should be a <progress-reporter> object."
REPORTER, which should be a <progress-reporter> object. When CLOSE? is true,
PORT is closed when the returned port is closed."
(match reporter
(($ <progress-reporter> start report stop)
(let* ((total 0)
@ -364,5 +365,6 @@ REPORTER, which should be a <progress-reporter> object."
;; trace.
(unless (zero? total)
(stop))
(close-port port)))))))
(when close?
(close-port port))))))))

101
guix/scripts/substitute.scm
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@ -188,9 +188,14 @@ again."
(sigaction SIGALRM SIG_DFL)
(apply values result)))))
(define* (fetch uri #:key (buffered? #t) (timeout? #t))
(define* (fetch uri #:key (buffered? #t) (timeout? #t)
(keep-alive? #f) (port #f))
"Return a binary input port to URI and the number of bytes it's expected to
provide."
provide.
When PORT is true, use it as the underlying I/O port for HTTP transfers; when
PORT is false, open a new connection for URI. When KEEP-ALIVE? is true, the
connection (typically PORT) is kept open once data has been fetched from URI."
(case (uri-scheme uri)
((file)
(let ((port (open-file (uri-path uri)
@ -206,7 +211,7 @@ provide."
;; sudo tc qdisc add dev eth0 root netem delay 1500ms
;; and then cancel with:
;; sudo tc qdisc del dev eth0 root
(let ((port #f))
(let ((port port))
(with-timeout (if timeout?
%fetch-timeout
0)
@ -217,10 +222,11 @@ provide."
(begin
(when (or (not port) (port-closed? port))
(set! port (guix:open-connection-for-uri
uri #:verify-certificate? #f))
uri #:verify-certificate? #f)))
(unless (or buffered? (not (file-port? port)))
(setvbuf port 'none)))
(setvbuf port 'none))
(http-fetch uri #:text? #f #:port port
#:keep-alive? keep-alive?
#:verify-certificate? #f))))))
(else
(leave (G_ "unsupported substitute URI scheme: ~a~%")
@ -478,17 +484,17 @@ indicates that PATH is unavailable at CACHE-URL."
(build-request (string->uri url) #:method 'GET #:headers headers)))
(define (at-most max-length lst)
"If LST is shorter than MAX-LENGTH, return it; otherwise return its
MAX-LENGTH first elements."
"If LST is shorter than MAX-LENGTH, return it and the empty list; otherwise
return its MAX-LENGTH first elements and its tail."
(let loop ((len 0)
(lst lst)
(result '()))
(match lst
(()
(reverse result))
(values (reverse result) '()))
((head . tail)
(if (>= len max-length)
(reverse result)
(values (reverse result) lst)
(loop (+ 1 len) tail (cons head result)))))))
(define* (http-multiple-get base-uri proc seed requests
@ -962,6 +968,68 @@ the URI, its compression method (a string), and the compressed file size."
(((uri compression file-size) _ ...)
(values uri compression file-size))))
(define %max-cached-connections
;; Maximum number of connections kept in cache by
;; 'open-connection-for-uri/cached'.
16)
(define open-connection-for-uri/cached
(let ((cache '()))
(lambda* (uri #:key fresh?)
"Return a connection for URI, possibly reusing a cached connection.
When FRESH? is true, delete any cached connections for URI and open a new
one. Return #f if URI's scheme is 'file' or #f."
(define host (uri-host uri))
(define scheme (uri-scheme uri))
(define key (list host scheme (uri-port uri)))
(and (not (memq scheme '(file #f)))
(match (assoc-ref cache key)
(#f
;; Open a new connection to URI and evict old entries from
;; CACHE, if any.
(let-values (((socket)
(guix:open-connection-for-uri
uri #:verify-certificate? #f))
((new-cache evicted)
(at-most (- %max-cached-connections 1) cache)))
(for-each (match-lambda
((_ . port)
(false-if-exception (close-port port))))
evicted)
(set! cache (alist-cons key socket new-cache))
socket))
(socket
(if (or fresh? (port-closed? socket))
(begin
(false-if-exception (close-port socket))
(set! cache (alist-delete key cache))
(open-connection-for-uri/cached uri))
(begin
;; Drain input left from the previous use.
(drain-input socket)
socket))))))))
(define (call-with-cached-connection uri proc)
(let ((port (open-connection-for-uri/cached uri)))
(catch #t
(lambda ()
(proc port))
(lambda (key . args)
;; If PORT was cached and the server closed the connection in the
;; meantime, we get EPIPE. In that case, open a fresh connection and
;; retry. We might also get 'bad-response or a similar exception from
;; (web response) later on, once we've sent the request.
(if (or (and (eq? key 'system-error)
(= EPIPE (system-error-errno `(,key ,@args))))
(memq key '(bad-response bad-header bad-header-component)))
(proc (open-connection-for-uri/cached uri #:fresh? #t))
(apply throw key args))))))
(define-syntax-rule (with-cached-connection uri port exp ...)
"Bind PORT with EXP... to a socket connected to URI."
(call-with-cached-connection uri (lambda (port) exp ...)))
(define* (process-substitution store-item destination
#:key cache-urls acl print-build-trace?)
"Substitute STORE-ITEM (a store file name) from CACHE-URLS, and write it to
@ -984,10 +1052,12 @@ DESTINATION as a nar file. Verify the substitute against ACL."
(G_ "Downloading ~a...~%") (uri->string uri)))
(let*-values (((raw download-size)
;; Note that Hydra currently generates Nars on the fly
;; and doesn't specify a Content-Length, so
;; DOWNLOAD-SIZE is #f in practice.
(fetch uri #:buffered? #f #:timeout? #f))
;; 'guix publish' without '--cache' doesn't specify a
;; Content-Length, so DOWNLOAD-SIZE is #f in this case.
(with-cached-connection uri port
(fetch uri #:buffered? #f #:timeout? #f
#:port port
#:keep-alive? #t)))
((progress)
(let* ((dl-size (or download-size
(and (equal? compression "none")
@ -1001,7 +1071,9 @@ DESTINATION as a nar file. Verify the substitute against ACL."
(uri->string uri) dl-size
(current-error-port)
#:abbreviation nar-uri-abbreviation))))
(progress-report-port reporter raw)))
;; Keep RAW open upon completion so we can later reuse
;; the underlying connection.
(progress-report-port reporter raw #:close? #f)))
((input pids)
;; NOTE: This 'progress' port of current process will be
;; closed here, while the child process doing the
@ -1218,6 +1290,7 @@ default value."
;;; Local Variables:
;;; eval: (put 'with-timeout 'scheme-indent-function 1)
;;; eval: (put 'with-cached-connection 'scheme-indent-function 2)
;;; End:
;;; substitute.scm ends here

15
nix/libstore/build.cc
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@ -3114,17 +3114,24 @@ void SubstitutionGoal::handleChildOutput(int fd, const string & data)
}
if (fd == substituter->fromAgent.readSide) {
/* Trim whitespace to the right. */
size_t end = data.find_last_not_of(" \t\n");
string trimmed = (end != string::npos) ? data.substr(0, end + 1) : data;
/* DATA may consist of several lines. Process them one by one. */
string input = data;
while (!input.empty()) {
/* Process up to the first newline. */
size_t end = input.find_first_of("\n");
string trimmed = (end != string::npos) ? input.substr(0, end) : input;
/* Update the goal's state accordingly. */
if (expectedHashStr == "") {
expectedHashStr = trimmed;
} else if (status == "") {
status = trimmed;
worker.wakeUp(shared_from_this());
} else {
printMsg(lvlError, format("unexpected substituter message '%1%'") % data);
printMsg(lvlError, format("unexpected substituter message '%1%'") % input);
}
input = (end != string::npos) ? input.substr(end + 1) : "";
}
}
}