summaryrefslogtreecommitdiff
path: root/guix/status.scm
blob: 984f329964d2cb1799a3b814a3332e6e00aa8bb8 (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (guix status)
  #:use-module (guix records)
  #:use-module (guix i18n)
  #:use-module ((guix ui) #:select (colorize-string))
  #:use-module (guix progress)
  #:autoload   (guix build syscalls) (terminal-columns)
  #:use-module ((guix build download)
                #:select (nar-uri-abbreviation))
  #:use-module (guix store)
  #:use-module (guix derivations)
  #:use-module (guix memoization)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-9 gnu)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 binary-ports)
  #:autoload   (ice-9 rdelim) (read-string)
  #:use-module (rnrs bytevectors)
  #:use-module ((system foreign)
                #:select (bytevector->pointer pointer->bytevector))
  #:export (build-event-output-port
            compute-status

            build-status
            build-status?
            build-status-building
            build-status-downloading
            build-status-builds-completed
            build-status-downloads-completed

            build?
            build
            build-derivation
            build-system
            build-log-file
            build-phase
            build-completion

            download?
            download
            download-item
            download-uri
            download-size
            download-start
            download-end
            download-transferred

            build-status-updater
            print-build-event
            print-build-event/quiet
            print-build-status

            with-status-report
            with-status-verbosity))

;;; Commentary:
;;;
;;; This module provides facilities to track the status of ongoing builds and
;;; downloads in a given session, as well as tools to report about the current
;;; status to user interfaces.  It does so by analyzing the output of
;;; 'current-build-output-port'.  The build status is maintained in a
;;; <build-status> record.
;;;
;;; Code:


;;;
;;; Build status tracking.
;;;

;; Builds and substitutions performed by the daemon.
(define-record-type* <build-status> build-status make-build-status
  build-status?
  (building     build-status-building             ;list of <build>
                (default '()))
  (downloading  build-status-downloading          ;list of <download>
                (default '()))
  (builds-completed build-status-builds-completed ;list of <build>
                    (default '()))
  (downloads-completed build-status-downloads-completed ;list of <download>
                       (default '())))

;; On-going or completed build.
(define-immutable-record-type <build>
  (%build derivation id system log-file phase completion)
  build?
  (derivation  build-derivation)                ;string (.drv file name)
  (id          build-id)                        ;#f | integer
  (system      build-system)                    ;string
  (log-file    build-log-file)                  ;#f | string
  (phase       build-phase                      ;#f | symbol
               set-build-phase)
  (completion  build-completion                 ;#f | integer (percentage)
               set-build-completion))

(define* (build derivation system #:key id log-file phase completion)
  "Return a new build."
  (%build derivation id system log-file phase completion))

;; On-going or completed downloads.  Downloads can be stem from substitutes
;; and from "builtin:download" fixed-output derivations.
(define-record-type <download>
  (%download item uri size start end transferred)
  download?
  (item         download-item)            ;store item
  (uri          download-uri)             ;string | #f
  (size         download-size)            ;integer | #f
  (start        download-start)           ;<time>
  (end          download-end)             ;#f | <time>
  (transferred  download-transferred))    ;integer

(define* (download item uri
                   #:key size
                   (start (current-time time-monotonic)) end
                   (transferred 0))
  "Return a new download."
  (%download item uri size start end transferred))

(define (matching-build drv)
  "Return a predicate that matches builds of DRV."
  (lambda (build)
    (string=? drv (build-derivation build))))

(define (matching-download item)
  "Return a predicate that matches downloads of ITEM."
  (lambda (download)
    (string=? item (download-item download))))

(define %phase-start-rx
  ;; Match the "starting phase" message emitted by 'gnu-build-system'.
  (make-regexp "^starting phase [`']([^']+)'"))

(define %percentage-line-rx
  ;; Things like CMake write lines like "[ 10%] gcc -c …".  This regexp
  ;; matches them.
  (make-regexp "^[[:space:]]*\\[ *([0-9]+)%\\]"))

(define %fraction-line-rx
  ;; The 'compiled-modules' derivations and Ninja produce reports like
  ;; "[ 1/32]" at the beginning of each line, while GHC prints "[ 6 of 45]".
  ;; This regexp matches these.
  (make-regexp "^[[:space:]]*\\[ *([0-9]+) *(/|of) *([0-9]+)\\]"))

(define (update-build status id line)
  "Update STATUS based on LINE, a build output line for ID that might contain
a completion indication."
  (define (find-build)
    (find (lambda (build)
            (and (build-id build)
                 (= (build-id build) id)))
          (build-status-building status)))

  (define (update %)
    (let ((build (find-build)))
      (build-status
       (inherit status)
       (building (cons (set-build-completion build %)
                       (delq build (build-status-building status)))))))

  (cond ((string-any #\nul line)
         ;; Don't try to match a regexp here.
         status)
        ((regexp-exec %percentage-line-rx line)
         =>
         (lambda (match)
           (let ((% (string->number (match:substring match 1))))
             (update %))))
        ((regexp-exec %fraction-line-rx line)
         =>
         (lambda (match)
           (let ((done  (string->number (match:substring match 1)))
                 (total (string->number (match:substring match 3))))
             (update (* 100. (/ done total))))))
        ((regexp-exec %phase-start-rx line)
         =>
         (lambda (match)
           (let ((phase (match:substring match 1))
                 (build (find-build)))
             (if build
                 (build-status
                  (inherit status)
                  (building
                   (cons (set-build-phase (set-build-completion build #f)
                                          (string->symbol phase))
                         (delq build (build-status-building status)))))
                 status))))
        (else
         status)))

(define* (compute-status event status
                         #:key
                         (current-time current-time)
                         (derivation-path->output-path
                          derivation-path->output-path))
  "Given EVENT, a tuple like (build-started \"/gnu/store/...-foo.drv\" ...),
compute a new status based on STATUS."
  (match event
    (('build-started drv "-" system log-file . rest)
     (let ((build (build drv system
                         #:id (match rest
                                ((pid . _) (string->number pid))
                                (_ #f))
                         #:log-file (if (string-null? log-file)
                                        #f
                                        log-file))))
       (build-status
        (inherit status)
        (building (cons build (build-status-building status))))))
    (((or 'build-succeeded 'build-failed) drv _ ...)
     (let ((build (find (matching-build drv)
                        (build-status-building status))))
       ;; If BUILD is #f, this may be because DRV corresponds to a
       ;; fixed-output derivation that is listed as a download.
       (if build
           (build-status
            (inherit status)
            (building (delq build (build-status-building status)))
            (builds-completed
             (cons build (build-status-builds-completed status))))
           status)))

    ;; Note: Ignore 'substituter-started' and 'substituter-succeeded' because
    ;; they're not as informative as 'download-started' and
    ;; 'download-succeeded'.

    (('download-started item uri (= string->number size))
     ;; This is presumably a fixed-output derivation so move it from
     ;; 'building' to 'downloading'.  XXX: This doesn't work in 'check' mode
     ;; because ITEM is different from DRV's output.
     (build-status
      (inherit status)
      (building (remove (lambda (build)
                          (let ((drv (build-derivation build)))
                            (equal? (false-if-exception
                                     (derivation-path->output-path drv))
                                    item)))
                        (build-status-building status)))
      (downloading (cons (download item uri #:size size
                                   #:start (current-time time-monotonic))
                         (build-status-downloading status)))))
    (('download-succeeded item uri (= string->number size))
     (let ((current (find (matching-download item)
                          (build-status-downloading status))))
       (build-status
        (inherit status)
        (downloading (delq current (build-status-downloading status)))
        (downloads-completed
         (cons (download item uri
                         #:size size
                         #:start (download-start current)
                         #:transferred size
                         #:end (current-time time-monotonic))
               (build-status-downloads-completed status))))))
    (('substituter-succeeded item _ ...)
     (match (find (matching-download item)
                  (build-status-downloading status))
       (#f
        ;; Presumably we already got a 'download-succeeded' event for ITEM,
        ;; everything is fine.
        status)
       (current
        ;; Maybe the build process didn't emit a 'download-succeeded' event
        ;; for ITEM, so remove CURRENT from the queue now.
        (build-status
         (inherit status)
         (downloading (delq current (build-status-downloading status)))
         (downloads-completed
          (cons (download item (download-uri current)
                          #:size (download-size current)
                          #:start (download-start current)
                          #:transferred (download-size current)
                          #:end (current-time time-monotonic))
                (build-status-downloads-completed status)))))))
    (('download-progress item uri
                         (= string->number size)
                         (= string->number transferred))
     (let ((downloads (remove (matching-download item)
                              (build-status-downloading status)))
           (current   (find (matching-download item)
                            (build-status-downloading status))))
       (build-status
        (inherit status)
        (downloading (cons (download item uri
                                     #:size size
                                     #:start
                                     (or (and current
                                              (download-start current))
                                         (current-time time-monotonic))
                                     #:transferred transferred)
                           downloads)))))
    (('build-log (? integer? pid) line)
     (update-build status pid line))
    (_
     status)))

(define (simultaneous-jobs status)
  "Return the number of on-going builds and downloads for STATUS."
  (+ (length (build-status-building status))
     (length (build-status-downloading status))))


;;;
;;; Rendering.
;;;

(define (extended-build-trace-supported?)
  "Return true if the currently used store is known to support \"extended
build traces\" such as \"@ download-progress\" traces."
  ;; Support for extended build traces was added in protocol version #x162.
  (and (current-store-protocol-version)
       (>= (current-store-protocol-version) #x162)))

(define (multiplexed-output-supported?)
  "Return true if the daemon supports \"multiplexed output\"--i.e., \"@
build-log\" traces."
  (and (current-store-protocol-version)
       (>= (current-store-protocol-version) #x163)))

(define isatty?*
  (mlambdaq (port)
    (isatty? port)))

(define spin!
  (let ((steps (circular-list "\\" "|" "/" "-")))
    (lambda (phase port)
      "Display a spinner on PORT.  If PHASE is true, display it as a hint of
the current build phase."
      (when (isatty?* port)
        (match steps
          ((first . rest)
           (set! steps rest)
           (display "\r\x1b[K" port)
           (display first port)
           (when phase
             (display " " port)
             ;; TRANSLATORS: The word "phase" here denotes a "build phase";
             ;; "~a" is a placeholder for the untranslated name of the current
             ;; build phase--e.g., 'configure' or 'build'.
             (format port (G_ "'~a' phase") phase))
           (force-output port)))))))

(define (color-output? port)
  "Return true if we should write colored output to PORT."
  (and (not (getenv "INSIDE_EMACS"))
       (not (getenv "NO_COLOR"))
       (isatty?* port)))

(define-syntax color-rules
  (syntax-rules ()
    "Return a procedure that colorizes the string it is passed according to
the given rules.  Each rule has the form:

  (REGEXP COLOR1 COLOR2 ...)

where COLOR1 specifies how to colorize the first submatch of REGEXP, and so
on."
    ((_ (regexp colors ...) rest ...)
     (let ((next (color-rules rest ...))
           (rx   (make-regexp regexp)))
       (lambda (str)
         (if (string-index str #\nul)
             str
             (match (regexp-exec rx str)
               (#f (next str))
               (m  (let loop ((n 1)
                              (c '(colors ...))
                              (result '()))
                     (match c
                       (()
                        (string-concatenate-reverse result))
                       ((first . tail)
                        (loop (+ n 1) tail
                              (cons (colorize-string (match:substring m n)
                                                     first)
                                    result)))))))))))
    ((_)
     (lambda (str)
       str))))

(define colorize-log-line
  ;; Take a string and return a possibly colorized string according to the
  ;; rules below.
  (color-rules
   ("^(phase)(.*)(succeeded after)(.*)(seconds)(.*)"
    GREEN    BOLD GREEN          RESET  GREEN  BLUE)
   ("^(phase)(.*)(failed after)(.*)(seconds)(.*)"
    RED BLUE RED BLUE RED BLUE)
   ("^(.*)(error|fail|failed|\\<FAIL|FAILED)([[:blank:]]*)(:)(.*)"
    RESET  RED                           BOLD         BOLD BOLD)
   ("^(.*)(warning)([[:blank:]]*)(:)(.*)"
    RESET  MAGENTA   BOLD        BOLD BOLD)))

(define (hook-message hook-type)
  "Return a human-readable string for the profile hook type HOOK-TYPE."
  (match hook-type
    ('info-dir
     (G_ "building directory of Info manuals..."))
    ('ghc-package-cache
     (G_ "building GHC package cache..."))
    ('ca-certificate-bundle
     (G_ "building CA certificate bundle..."))
    ('glib-schemas
     (G_ "generating GLib schema cache..."))
    ('gtk-icon-themes
     (G_ "creating GTK+ icon theme cache..."))
    ('gtk-im-modules
     (G_ "building cache files for GTK+ input methods..."))
    ('xdg-desktop-database
     (G_ "building XDG desktop file cache..."))
    ('xdg-mime-database
     (G_ "building XDG MIME database..."))
    ('fonts-dir
     (G_ "building fonts directory..."))
    ('texlive-configuration
     (G_ "building TeX Live configuration..."))
    ('manual-database
     (G_ "building database for manual pages..."))
    ('package-cache                    ;package cache generated by 'guix pull'
     (G_ "building package cache..."))
    (_ #f)))

(define* (print-build-event event old-status status
                            #:optional (port (current-error-port))
                            #:key
                            (colorize? (color-output? port))
                            (print-log? #t))
  "Print information about EVENT and STATUS to PORT.  When COLORIZE? is true,
produce colorful output.  When PRINT-LOG? is true, display the build log in
addition to build events."
  (define info
    (if colorize?
        (cut colorize-string <> 'BOLD)
        identity))

  (define success
    (if colorize?
        (cut colorize-string <> 'GREEN 'BOLD)
        identity))

  (define failure
    (if colorize?
        (cut colorize-string <> 'RED 'BOLD)
        identity))

  (define (report-build-progress phase %)
    (let ((% (min (max % 0) 100)))                ;sanitize
      (erase-current-line port)
      (let* ((prefix (format #f "~3d% ~@['~a' ~]"
                            (inexact->exact (round %))
                            (case phase
                              ((build) #f)        ;not useful to display it
                              (else phase))))
             (length (string-length prefix)))
        (display prefix port)
        (display (progress-bar % (- (current-terminal-columns) length))
                 port))
      (force-output port)))

  (define print-log-line
    (if print-log?
        (if colorize?
            (lambda (id line)
              (display (colorize-log-line line) port))
            (lambda (id line)
              (display line port)))
        (lambda (id line)
          (match (build-status-building status)
            ((build)                              ;single job
             (match (build-completion build)
               ((? number? %)
                (report-build-progress (build-phase build) %))
               (_
                (spin! (build-phase build) port))))
            (_
             (spin! #f port))))))

  (define erase-current-line*
    (if (isatty?* port)
        (lambda (port)
          (erase-current-line port)
          (force-output port))
        (const #t)))

  (unless print-log?
    (erase-current-line* port))             ;clear the spinner or progress bar
  (match event
    (('build-started drv . _)
     (let ((properties (derivation-properties
                        (read-derivation-from-file drv))))
       (match (assq-ref properties 'type)
         ('graft
           (let ((count (match (assq-ref properties 'graft)
                          (#f  0)
                          (lst (or (assq-ref lst 'count) 0)))))
             (format port (info (N_ "applying ~a graft for ~a..."
                                    "applying ~a grafts for ~a..."
                                    count))
                     count drv)))
         ('profile-hook
          (let ((hook-type (assq-ref properties 'hook)))
            (or (and=> (hook-message hook-type)
                       (lambda (msg)
                         (format port (info msg))))
                (format port (info (G_ "running profile hook of type '~a'..."))
                        hook-type))))
         (_
          (format port (info (G_ "building ~a...")) drv))))
     (newline port))
    (('build-succeeded drv . _)
     (when (or print-log? (not (extended-build-trace-supported?)))
       (format port (success (G_ "successfully built ~a")) drv)
       (newline port))
     (match (build-status-building status)
       (() #t)
       (ongoing                                   ;when max-jobs > 1
        (format port
                (N_ "The following build is still in progress:~%~{  ~a~%~}~%"
                    "The following builds are still in progress:~%~{  ~a~%~}~%"
                    (length ongoing))
                (map build-derivation ongoing)))))
    (('build-failed drv . _)
     (format port (failure (G_ "build of ~a failed")) drv)
     (newline port)
     (match (derivation-log-file drv)
       (#f
        (format port (failure (G_ "Could not find build log for '~a'."))
                drv))
       (log
        (format port (info (G_ "View build log at '~a'.")) log)))
     (newline port))
    (('substituter-started item _ ...)
     (when (or print-log? (not (extended-build-trace-supported?)))
       (format port (info (G_ "substituting ~a...")) item)
       (newline port)))
    (('download-started item uri _ ...)
     (format port (info (G_ "downloading from ~a...")) uri)
     (newline port))
    (('download-progress item uri
                         (= string->number size)
                         (= string->number transferred))
     ;; Print a progress bar, but only if there's only one on-going
     ;; job--otherwise the output would be intermingled.
     (when (= 1 (simultaneous-jobs status))
       (match (find (matching-download item)
                    (build-status-downloading status))
         (#f #f)                                  ;shouldn't happen!
         (download
          ;; XXX: It would be nice to memoize the abbreviation.
          (let ((uri (if (string-contains uri "/nar/")
                         (nar-uri-abbreviation uri)
                         (basename uri))))
            (display-download-progress uri size
                                       #:start-time
                                       (download-start download)
                                       #:transferred transferred))))))
    (('substituter-succeeded item _ ...)
     ;; If there are no jobs running, we already reported download completion
     ;; so there's nothing left to do.
     (unless (and (zero? (simultaneous-jobs status))
                  (extended-build-trace-supported?))
       (format port (success (G_ "substitution of ~a complete")) item)
       (newline port)))
    (('substituter-failed item _ ...)
     (format port (failure (G_ "substitution of ~a failed")) item)
     (newline port))
    (('hash-mismatch item algo expected actual _ ...)
     ;; TRANSLATORS: The final string looks like "sha256 hash mismatch for
     ;; /gnu/store/…-sth:", where "sha256" is the hash algorithm.
     (format port (failure (G_ "~a hash mismatch for ~a:")) algo item)
     (newline port)
     (format port (info (G_ "\
  expected hash: ~a
  actual hash:   ~a~%"))
             expected actual))
    (('build-remote drv host _ ...)
     (format port (info (G_ "offloading build of ~a to '~a'")) drv host)
     (newline port))
    (('build-log pid line)
     (if (multiplexed-output-supported?)
         (if (not pid)
             (begin
               ;; LINE comes from the daemon, not from builders.  Let it
               ;; through.
               (display line port)
               (force-output port))
             (print-log-line pid line))
         (cond ((string-prefix? "substitute: " line)
                ;; The daemon prefixes early messages coming with 'guix
                ;; substitute' with "substitute:".  These are useful ("updating
                ;; substitutes from URL"), so let them through.
                (display line port)
                (force-output port))
               ((string-prefix? "waiting for locks" line)
                ;; This is when a derivation is already being built and we're just
                ;; waiting for the build to complete.
                (display (info (string-trim-right line)) port)
                (newline))
               (else
                (print-log-line pid line)))))
    (_
     event)))

(define* (print-build-event/quiet event old-status status
                                  #:optional
                                  (port (current-error-port))
                                  #:key
                                  (colorize? (color-output? port)))
  (print-build-event event old-status status port
                     #:colorize? colorize?
                     #:print-log? #f))

(define* (build-status-updater #:optional (on-change (const #t)))
  "Return a procedure that can be passed to 'build-event-output-port'.  That
procedure computes the new build status upon each event and calls ON-CHANGE:

  (ON-CHANGE event status new-status)

ON-CHANGE can display the build status, build events, etc."
  (lambda (event status)
    (let ((new (compute-status event status)))
      (on-change event status new)
      new)))


;;;
;;; Build port.
;;;

(define (maybe-utf8->string bv)
  "Attempt to decode BV as UTF-8 string and return it.  Gracefully handle the
case where BV does not contain only valid UTF-8."
  (catch 'decoding-error
    (lambda ()
      (utf8->string bv))
    (lambda _
      ;; This is the sledgehammer but it's the only safe way we have to
      ;; properly handle this.  It's expensive but it's rarely needed.
      (let ((port (open-bytevector-input-port bv)))
        (set-port-encoding! port "UTF-8")
        (set-port-conversion-strategy! port 'substitute)
        (let ((str (read-string port)))
          (close-port port)
          str)))))

(define (bytevector-index bv number offset count)
  "Search for NUMBER in BV starting from OFFSET and reading up to COUNT bytes;
return the offset where NUMBER first occurs or #f if it could not be found."
  (let loop ((offset offset)
             (count count))
    (cond ((zero? count) #f)
          ((= (bytevector-u8-ref bv offset) number) offset)
          (else (loop (+ 1 offset) (- count 1))))))

(define (split-lines str)
  "Split STR into lines in a way that preserves newline characters."
  (let loop ((str str)
             (result '()))
    (if (string-null? str)
        (reverse result)
        (match (string-index str #\newline)
          (#f
           (loop "" (cons str result)))
          (index
           (loop (string-drop str (+ index 1))
                 (cons (string-take str (+ index 1)) result)))))))

(define* (build-event-output-port proc #:optional (seed (build-status)))
  "Return an output port for use as 'current-build-output-port' that calls
PROC with its current state value, initialized with SEED, on every build
event.  Build events passed to PROC are tuples corresponding to the \"build
traces\" produced by the daemon:

  (build-started \"/gnu/store/...-foo.drv\" ...)
  (substituter-started \"/gnu/store/...-foo\" ...)

and so on.

The second return value is a thunk to retrieve the current state."
  (define %fragments
    ;; Line fragments received so far.
    '())

  (define %state
    ;; Current state for PROC.
    seed)

  ;; When true, this represents the current state while reading a
  ;; "@ build-log" trace: the current builder PID, the previously-read
  ;; bytevectors, and the number of bytes that remain to be read.
  (define %build-output-pid #f)
  (define %build-output '())
  (define %build-output-left #f)

  (define (process-line line)
    (cond ((string-prefix? "@ " line)
           ;; Note: Drop the trailing \n, and use 'string-split' to preserve
           ;; spaces (the log file part of 'build-started' events can be the
           ;; empty string.)
           (match (string-split (string-drop (string-drop-right line 1) 2)
                                #\space)
             (("build-log" (= string->number pid) (= string->number len))
              (set! %build-output-pid pid)
              (set! %build-output '())
              (set! %build-output-left len))
             (((= string->symbol event-name) args ...)
              (set! %state
                (proc (cons event-name args)
                      %state)))))
          (else
           (set! %state (proc (list 'build-log #f line)
                              %state)))))

  (define (process-build-output pid output)
    ;; Transform OUTPUT in 'build-log' events or download events as generated
    ;; by extended build traces.
    (define (line->event line)
      (match (and (string-prefix? "@ " line)
                  (string-tokenize (string-drop line 2)))
        ((type . args)
         (if (or (string-prefix? "download-" type)
                 (string=? "build-remote" type))
             (cons (string->symbol type) args)
             `(build-log ,pid ,line)))
        (_
         `(build-log ,pid ,line))))

    (let* ((lines  (split-lines output))
           (events (map line->event lines)))
      (set! %state (fold proc %state events))))

  (define (bytevector-range bv offset count)
    (let ((ptr (bytevector->pointer bv offset)))
      (pointer->bytevector ptr count)))

  (define (write! bv offset count)
    (if %build-output-pid
        (let ((keep (min count %build-output-left)))
          (set! %build-output
            (let ((bv* (make-bytevector keep)))
              (bytevector-copy! bv offset bv* 0 keep)
              (cons bv* %build-output)))
          (set! %build-output-left
            (- %build-output-left keep))

          (when (zero? %build-output-left)
            (process-build-output %build-output-pid
                                  (string-concatenate-reverse
                                   (map maybe-utf8->string %build-output))) ;XXX
            (set! %build-output '())
            (set! %build-output-pid #f))
          keep)
        (match (bytevector-index bv (char->integer #\newline)
                                 offset count)
          ((? integer? cr)
           (let* ((tail (maybe-utf8->string
                         (bytevector-range bv offset (- cr -1 offset))))
                  (line (string-concatenate-reverse
                         (cons tail %fragments))))
             (process-line line)
             (set! %fragments '())
             (- cr -1 offset)))
          (#f
           (unless (zero? count)
             (let ((str (maybe-utf8->string
                         (bytevector-range bv offset count))))
               (set! %fragments (cons str %fragments))))
           count))))

  (define port
    (make-custom-binary-output-port "filtering-input-port"
                                    write!
                                    #f #f
                                    #f))

  ;; The build port actually receives Unicode strings.
  (set-port-encoding! port "UTF-8")
  (setvbuf port 'line)
  (values port (lambda () %state)))

(define (call-with-status-report on-event thunk)
  (parameterize ((current-terminal-columns (terminal-columns))
                 (current-build-output-port
                  (build-event-output-port (build-status-updater on-event))))
    (thunk)))

(define-syntax-rule (with-status-report on-event exp ...)
  "Set up build status reporting to the user using the ON-EVENT procedure;
evaluate EXP... in that context."
  (call-with-status-report on-event (lambda () exp ...)))

(define (logger-for-level level)
  "Return the logging procedure that corresponds to LEVEL."
  (cond ((<= level 0) (const #t))
        ((= level 1)  print-build-event/quiet)
        (else         print-build-event)))

(define (call-with-status-verbosity level thunk)
  (call-with-status-report (logger-for-level level) thunk))

(define-syntax-rule (with-status-verbosity level exp ...)
  "Set up build status reporting to the user at the given LEVEL: 0 means
silent, 1 means quiet, 2 means verbose.  Evaluate EXP... in that context."
  (call-with-status-verbosity level (lambda () exp ...)))