| blob | 0cc53ad23323d9ee7d06115fa9039c713cede7c5 |
1 ;;; nnvirtual.el --- virtual newsgroups access for Gnus
3 ;; Copyright (C) 1994-2011 Free Software Foundation, Inc.
5 ;; Author: David Moore <dmoore@ucsd.edu>
6 ;; Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; Masanobu UMEDA <umerin@flab.flab.fujitsu.junet>
8 ;; Keywords: news
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software: you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation, either version 3 of the License, or
15 ;; (at your option) any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;;; Commentary:
27 ;; The other access methods (nntp, nnspool, etc) are general news
28 ;; access methods. This module relies on Gnus and can not be used
29 ;; separately.
31 ;;; Code:
46 "If non-nil, always scan groups for unread articles when entering a group.
47 If this variable is nil and you read articles in a component group
48 after the virtual group has been activated, the read articles from the
57 \f
64 "Table of rules on how to map between component group and article number to virtual article number.")
73 "Compressed sequence of read articles on the virtual group as computed from the unread status of individual component groups.")
76 "Compressed marks alist for the virtual group as computed from the marks of individual component groups.")
79 "T if we have already installed the group info for this group, and shouldn't blast over it again.")
85 \f
87 ;;; Interface functions.
93 server fetch-old)
98 'headers
103 cgroup carticle article result prefix)
113 ;; FIX FIX FIX we want to check the cache!
114 ;; This is probably evil if people have set
115 ;; gnus-use-cache to nil themselves, but I
116 ;; have no way of finding the true value of it.
119 articles cgroup nil))))
121 ;; If we got HEAD headers, we convert them into NOV
122 ;; headers. This is slow, inefficient and, come to think
123 ;; of it, downright evil. So sue me. I couldn't be
124 ;; bothered to write a header parse routine that could
125 ;; parse a mixed HEAD/NOV buffer.
135 ;; We remove this article from the articles list, if
136 ;; anything is left in the articles list after going through
137 ;; the entire buffer, then those articles have been
138 ;; expired or canceled, so we appropriately update the
139 ;; component group below. They should be coming up
140 ;; generally in order, so this shouldn't be slow.
145 ;; This line has no reverse mapping, that means it
146 ;; was an extra article reference returned by nntp.
150 ;; Otherwise insert the virtual article number,
151 ;; and clean up the xrefs.
154 prefix system-name)
156 )
161 ;; Anything left in articles is expired or canceled.
162 ;; Could be smart and not tell it about articles already known?
165 )
167 ;; The headers are ready for reading, so they are inserted into
168 ;; the nntp-server-buffer, which is where Gnus expects to find
169 ;; them.
174 ;; FIX FIX FIX, we should be able to sort faster than
175 ;; this if needed, since each cgroup is sorted, we just
176 ;; need to merge
187 ;; This is a fetch by Message-ID.
198 nnvirtual-last-accessed-component-group)))
201 ;; This is a fetch by number.
216 ;; We bind this here to avoid double decoding.
225 defs))
228 t
230 nnvirtual-mapping-offsets nil
231 nnvirtual-mapping-len 0
232 nnvirtual-mapping-reads nil
233 nnvirtual-mapping-marks nil
234 nnvirtual-info-installed nil)
236 ;; Go through the newsrc alist and find all component groups.
238 group)
241 ;; Add this group to the list of component groups.
246 t)))
265 nnvirtual-mapping-len nnvirtual-mapping-len group))))
270 'unknown
276 nnvirtual-last-accessed-component-group nil))))
283 ;; The component group might be a virtual group.
287 mark)
294 t)
308 ;; Install the precomputed lists atomically, so the virtual group
309 ;; is not left in a half-way state in case of C-g.
317 t))
323 ;; copy over existing marks first, in case they set anything
325 ;; do a catchup on all component groups
328 ;; Make sure all groups are activated.
333 nnvirtual-component-groups)
339 "Return the real group and article for virtual GROUP and ARTICLE."
363 group article))
368 \f
369 ;;; Internal functions.
372 "Convert HEAD headers into NOV headers."
381 "Edit current NOV header in current buffer to have an xref to the component group, and also server prefix any existing xref lines."
382 ;; Move to beginning of Xref field, creating a slot if needed.
390 ;; Remove any spaces at the beginning of the Xref field.
399 ;; If there were existing xref lines, clean them up to have the correct
400 ;; component server prefix.
411 nil t)
421 ;; Ensure a trailing \t.
434 "Copy marks from the virtual group to the component groups.
435 If READ-P is not nil, update the (un)read status of the components.
436 If UPDATE-P is not nil, call gnus-group-update-group on the components."
446 nil
451 type groups info)
453 ;; Ok, atomically move all of the (un)read info, clear any old
454 ;; marks, and move all of the current marks. This way if someone
455 ;; hits C-g, you won't leave the component groups in a half-way state.
457 ;; move (un)read
458 ;; bind for workaround guns-update-read-articles
463 ;; clear all existing marks on the component groups
468 info
471 nil))))
473 ;; Ok, currently type-marks is an assq list with keys of a mark type,
474 ;; with data of an assq list with keys of component group names
475 ;; and the articles which correspond to that key/group pair.
481 nil t))))
483 ;; possibly update the display, it is really slow
490 "Return the prefixed name of the current nnvirtual group."
495 ;;; This is currently O(kn^2) to merge n lists of length k.
496 ;;; You could do it in O(knlogn), but we have a small n, and the
497 ;;; overhead of the other approach is probably greater.
499 "Merge many sorted lists of numbers."
505 ;;; We map between virtual articles and real articles in a manner
506 ;;; which keeps the size of the virtual active list the same as the
507 ;;; sum of the component active lists.
509 ;;; To achieve fair mixing of the groups, the last article in each of
510 ;;; N component groups will be in the last N articles in the virtual
511 ;;; group.
513 ;;; If you have 3 components A, B and C, with articles 1-8, 1-5, and
514 ;;; 6-7 respectively, then the virtual article numbers look like:
515 ;;;
516 ;;; 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
517 ;;; A1 A2 A3 A4 B1 A5 B2 A6 B3 A7 B4 C6 A8 B5 C7
519 ;;; To compute these mappings we generate a couple tables and then
520 ;;; do some fast operations on them. Tables for the example above:
521 ;;;
522 ;;; Offsets - [(A 0) (B -3) (C -1)]
523 ;;;
524 ;;; a b c d e
525 ;;; Mapping - ([ 3 0 1 3 0 ]
526 ;;; [ 6 3 2 9 3 ]
527 ;;; [ 8 6 3 15 9 ])
528 ;;;
529 ;;; (note column 'e' is different in real algorithm, which is slightly
530 ;;; different than described here, but this gives you the methodology.)
531 ;;;
532 ;;; The basic idea is this, when going from component->virtual, apply
533 ;;; the appropriate offset to the article number. Then search the first
534 ;;; column of the table for a row where 'a' is less than or equal to the
535 ;;; modified number. You can see that only group A can therefore go to
536 ;;; the first row, groups A and B to the second, and all to the last.
537 ;;; The third column of the table is telling us the number of groups
538 ;;; which might be able to reach that row (it might increase by more than
539 ;;; 1 if several groups have the same size).
540 ;;; Then column 'b' provides an additional offset you apply when you have
541 ;;; found the correct row. You then multiply by 'c' and add on the groups
542 ;;; _position_ in the offset table. The basic idea here is that on
543 ;;; any given row we are going to map back and forth using X'=X*c+Y and
544 ;;; X=(X'/c), Y=(X' mod c). Then once you've done this transformation,
545 ;;; you apply a final offset from column 'e' to give the virtual article.
546 ;;;
547 ;;; Going the other direction, you instead search on column 'd' instead
548 ;;; of 'a', and apply everything in reverse order.
550 ;;; Convert component -> virtual:
551 ;;; set num = num - Offset(group)
552 ;;; find first row in Mapping where num <= 'a'
553 ;;; num = (num-'b')*c + Position(group) + 'e'
555 ;;; Convert virtual -> component:
556 ;;; find first row in Mapping where num <= 'd'
557 ;;; num = num - 'e'
558 ;;; group_pos = num mod 'c'
559 ;;; num = (num / 'c') + 'b' + Offset(group_pos)
561 ;;; Easy no? :)
562 ;;;
563 ;;; Well actually, you need to keep column e offset smaller by the 'c'
564 ;;; column for that line, and always add 1 more when going from
565 ;;; component -> virtual. Otherwise you run into a problem with
566 ;;; unique reverse mapping.
569 "Return a cons of the component group and article corresponding to the given virtual ARTICLE."
571 entry group-pos)
584 ))
585 ))
590 "Return the virtual article number corresponding to the given component GROUP and ARTICLE."
594 entry)
596 group-pos))))
599 group-pos))))
608 group-pos
612 )))
616 "Return list of virtual article numbers for all ARTICLES in GROUP.
617 The ARTICLES should be sorted, and can be a compressed sequence.
618 If any of the article numbers has no corresponding virtual article,
619 then it is left out of the result."
626 j a)
630 ;; If this is slow, you can optimize by moving article checking
631 ;; into here. You don't have to recompute the group-pos,
632 ;; nor scan the table every time.
640 "Return an association list of component article numbers.
641 These are indexed by elements of nnvirtual-component-groups, based on
642 the sequence ARTICLES of virtual article numbers. ARTICLES should be
643 sorted, and can be a compressed sequence. If any of the article
644 numbers has no corresponding component article, then it is left out of
645 the result."
649 a i j article entry)
653 j a)
662 carticles)
663 carticles))
667 "Build the tables necessary to map between component (group, article) to virtual article.
668 Generate the set of read messages and marks for the virtual group
669 based on the marks on the component groups."
674 actives all-unreads all-marks
675 active min max size unreads marks
676 next-M next-tot
677 reads beg)
678 ;; Ok, we loop over all component groups and collect a lot of
679 ;; information:
680 ;; Into actives we place (g size max), where size is max-min+1.
681 ;; Into all-unreads we put (g unreads).
682 ;; Into all-marks we put (g marks).
683 ;; We also increment cnt and tot here, and compute M (max of sizes).
691 ;; store active information
693 ;; collect unread/mark info for later
699 marks))
702 ;; count groups, total #articles, and max size
707 nnvirtual-component-groups)
709 ;; Number of articles in the virtual group.
713 ;; We want the actives list sorted by size, to build the tables.
716 ;; Build the offset table. Largest sized groups are at the front.
723 actives))))
725 ;; Build the mapping table.
732 ;; make current row in table
734 nnvirtual-mapping-table)
735 ;; update M and tot
738 ;; subtract the current size from all entries.
740 ;; remove anything that went to 0.
747 ;; Now that the mapping tables are generated, we can convert
748 ;; and combine the separate component unreads and marks lists
749 ;; into single lists of virtual article numbers.
754 all-unreads)))
760 'nnvirtual-merge-sorted-lists
765 all-marks)))))
766 gnus-article-mark-lists))
768 ;; Remove any empty marks lists, and store.
774 ;; We need to convert the unreads to reads. We compress the
775 ;; sequence as we go, otherwise it could be huge.
777 unreads)
780 ;; try to get a range.
788 ))
794 ;; Store the reads list for later use.
797 ;; Throw flag to show we changed the info.
799 ))
803 ;;; nnvirtual.el ends here