lisp/gnus/registry.el

   1 ;;; registry.el --- Track and remember data items by various fields
   2
   3 ;; Copyright (C) 2011-2013 Free Software Foundation, Inc.
   4
   5 ;; Author: Teodor Zlatanov <tzz@lifelogs.com>
   6 ;; Keywords: data
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software: you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation, either version 3 of the License, or
  13 ;; (at your option) any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; This library provides a general-purpose EIEIO-based registry
  26 ;; database with persistence, initialized with these fields:
  27
  28 ;; version: a float, 0.1 currently (don't change it)
  29
  30 ;; max-hard: an integer, default 5000000
  31
  32 ;; max-soft: an integer, default 50000
  33
  34 ;; precious: a list of symbols
  35
  36 ;; tracked: a list of symbols
  37
  38 ;; tracker: a hashtable tuned for 100 symbols to track (you should
  39 ;; only access this with the :lookup2-function and the
  40 ;; :lookup2+-function)
  41
  42 ;; data: a hashtable with default size 10K and resize threshold 2.0
  43 ;; (this reflects the expected usage so override it if you know better)
  44
  45 ;; ...plus methods to do all the work: `registry-search',
  46 ;; `registry-lookup', `registry-lookup-secondary',
  47 ;; `registry-lookup-secondary-value', `registry-insert',
  48 ;; `registry-delete', `registry-prune', `registry-size' which see
  49
  50 ;; and with the following properties:
  51
  52 ;; Every piece of data has a unique ID and some general-purpose fields
  53 ;; (F1=D1, F2=D2, F3=(a b c)...) expressed as an alist, e.g.
  54
  55 ;; ((F1 D1) (F2 D2) (F3 a b c))
  56
  57 ;; Note that whether a field has one or many pieces of data, the data
  58 ;; is always a list of values.
  59
  60 ;; The user decides which fields are "precious", F2 for example.  At
  61 ;; PRUNE TIME (when the :prune-function is called), the registry will
  62 ;; trim any entries without the F2 field until the size is :max-soft
  63 ;; or less.  No entries with the F2 field will be removed at PRUNE
  64 ;; TIME.
  65
  66 ;; When an entry is inserted, the registry will reject new entries
  67 ;; if they bring it over the max-hard limit, even if they have the F2
  68 ;; field.
  69
  70 ;; The user decides which fields are "tracked", F1 for example.  Any
  71 ;; new entry is then indexed by all the tracked fields so it can be
  72 ;; quickly looked up that way.  The data is always a list (see example
  73 ;; above) and each list element is indexed.
  74
  75 ;; Precious and tracked field names must be symbols.  All other
  76 ;; fields can be any other Emacs Lisp types.
  77
  78 ;;; Code:
  79
  80 (eval-when-compile (require 'cl))
  81
  82 (require 'eieio)
  83 (require 'eieio-base)
  84
  85 (defclass registry-db (eieio-persistent)
  86   ((version :initarg :version
  87             :initform 0.1
  88             :type float
  89             :custom float
  90             :documentation "The registry version.")
  91    (max-hard :initarg :max-hard
  92              :initform 5000000
  93              :type integer
  94              :custom integer
  95              :documentation "Never accept more than this many elements.")
  96    (max-soft :initarg :max-soft
  97              :initform 50000
  98              :type integer
  99              :custom integer
 100              :documentation "Prune as much as possible to get to this size.")
 101    (prune-factor
 102     :initarg :prune-factor
 103     :initform 0.1
 104     :type float
 105     :custom float
 106     :documentation "At the max-hard limit, prune size * this entries.")
 107    (tracked :initarg :tracked
 108             :initform nil
 109             :type t
 110             :documentation "The tracked (indexed) fields, a list of symbols.")
 111    (precious :initarg :precious
 112              :initform nil
 113              :type t
 114              :documentation "The precious fields, a list of symbols.")
 115    (tracker :initarg :tracker
 116             :type hash-table
 117             :documentation "The field tracking hashtable.")
 118    (data :initarg :data
 119          :type hash-table
 120          :documentation "The data hashtable.")))
 121
 122 (defmethod initialize-instance :AFTER ((this registry-db) slots)
 123   "Set value of data slot of THIS after initialization."
 124   (with-slots (data tracker) this
 125     (unless (member :data slots)
 126       (setq data
 127             (make-hash-table :size 10000 :rehash-size 2.0 :test 'equal)))
 128     (unless (member :tracker slots)
 129       (setq tracker (make-hash-table :size 100 :rehash-size 2.0)))))
 130
 131 (defmethod registry-lookup ((db registry-db) keys)
 132   "Search for KEYS in the registry-db THIS.
 133 Returns an alist of the key followed by the entry in a list, not a cons cell."
 134   (let ((data (oref db :data)))
 135     (delq nil
 136           (mapcar
 137            (lambda (k)
 138              (when (gethash k data)
 139                (list k (gethash k data))))
 140            keys))))
 141
 142 (defmethod registry-lookup-breaks-before-lexbind ((db registry-db) keys)
 143   "Search for KEYS in the registry-db THIS.
 144 Returns an alist of the key followed by the entry in a list, not a cons cell."
 145   (let ((data (oref db :data)))
 146     (delq nil
 147           (loop for key in keys
 148                 when (gethash key data)
 149                 collect (list key (gethash key data))))))
 150
 151 (defmethod registry-lookup-secondary ((db registry-db) tracksym
 152                                       &optional create)
 153   "Search for TRACKSYM in the registry-db THIS.
 154 When CREATE is not nil, create the secondary index hashtable if needed."
 155   (let ((h (gethash tracksym (oref db :tracker))))
 156     (if h
 157         h
 158       (when create
 159         (puthash tracksym
 160                  (make-hash-table :size 800 :rehash-size 2.0 :test 'equal)
 161                  (oref db :tracker))
 162         (gethash tracksym (oref db :tracker))))))
 163
 164 (defmethod registry-lookup-secondary-value ((db registry-db) tracksym val
 165                                             &optional set)
 166   "Search for TRACKSYM with value VAL in the registry-db THIS.
 167 When SET is not nil, set it for VAL (use t for an empty list)."
 168   ;; either we're asked for creation or there should be an existing index
 169   (when (or set (registry-lookup-secondary db tracksym))
 170     ;; set the entry if requested,
 171     (when set
 172       (puthash val (if (eq t set) '() set)
 173                (registry-lookup-secondary db tracksym t)))
 174     (gethash val (registry-lookup-secondary db tracksym))))
 175
 176 (defun registry--match (mode entry check-list)
 177   ;; for all members
 178   (when check-list
 179     (let ((key (nth 0 (nth 0 check-list)))
 180           (vals (cdr-safe (nth 0 check-list)))
 181           found)
 182       (while (and key vals (not found))
 183         (setq found (case mode
 184                       (:member
 185                        (member (car-safe vals) (cdr-safe (assoc key entry))))
 186                       (:regex
 187                        (string-match (car vals)
 188                                      (mapconcat
 189                                       'prin1-to-string
 190                                       (cdr-safe (assoc key entry))
 191                                       "\0"))))
 192               vals (cdr-safe vals)))
 193       (or found
 194           (registry--match mode entry (cdr-safe check-list))))))
 195
 196 (defmethod registry-search ((db registry-db) &rest spec)
 197   "Search for SPEC across the registry-db THIS.
 198 For example calling with :member '(a 1 2) will match entry '((a 3 1)).
 199 Calling with :all t (any non-nil value) will match all.
 200 Calling with :regex '\(a \"h.llo\") will match entry '((a \"hullo\" \"bye\").
 201 The test order is to check :all first, then :member, then :regex."
 202   (when db
 203     (let ((all (plist-get spec :all))
 204           (member (plist-get spec :member))
 205           (regex (plist-get spec :regex)))
 206       (loop for k being the hash-keys of (oref db :data)
 207             using (hash-values v)
 208             when (or
 209                   ;; :all non-nil returns all
 210                   all
 211                   ;; member matching
 212                   (and member (registry--match :member v member))
 213                   ;; regex matching
 214                   (and regex (registry--match :regex v regex)))
 215             collect k))))
 216
 217 (defmethod registry-delete ((db registry-db) keys assert &rest spec)
 218   "Delete KEYS from the registry-db THIS.
 219 If KEYS is nil, use SPEC to do a search.
 220 Updates the secondary ('tracked') indices as well.
 221 With assert non-nil, errors out if the key does not exist already."
 222   (let* ((data (oref db :data))
 223          (keys (or keys
 224                    (apply 'registry-search db spec)))
 225          (tracked (oref db :tracked)))
 226
 227     (dolist (key keys)
 228       (let ((entry (gethash key data)))
 229         (when assert
 230           (assert entry nil
 231                   "Key %s does not exists in database" key))
 232         ;; clean entry from the secondary indices
 233         (dolist (tr tracked)
 234           ;; is this tracked symbol indexed?
 235           (when (registry-lookup-secondary db tr)
 236             ;; for every value in the entry under that key...
 237             (dolist (val (cdr-safe (assq tr entry)))
 238               (let* ((value-keys (registry-lookup-secondary-value
 239                                   db tr val)))
 240                 (when (member key value-keys)
 241                   ;; override the previous value
 242                   (registry-lookup-secondary-value
 243                    db tr val
 244                    ;; with the indexed keys MINUS the current key
 245                    ;; (we pass t when the list is empty)
 246                    (or (delete key value-keys) t)))))))
 247         (remhash key data)))
 248     keys))
 249
 250 (defmethod registry-size ((db registry-db))
 251   "Returns the size of the registry-db object THIS.
 252 This is the key count of the :data slot."
 253   (hash-table-count (oref db :data)))
 254
 255 (defmethod registry-full ((db registry-db))
 256   "Checks if registry-db THIS is full."
 257   (>= (registry-size db)
 258       (oref db :max-hard)))
 259
 260 (defmethod registry-insert ((db registry-db) key entry)
 261   "Insert ENTRY under KEY into the registry-db THIS.
 262 Updates the secondary ('tracked') indices as well.
 263 Errors out if the key exists already."
 264
 265   (assert (not (gethash key (oref db :data))) nil
 266           "Key already exists in database")
 267
 268   (assert (not (registry-full db))
 269           nil
 270           "registry max-hard size limit reached")
 271
 272   ;; store the entry
 273   (puthash key entry (oref db :data))
 274
 275   ;; store the secondary indices
 276   (dolist (tr (oref db :tracked))
 277     ;; for every value in the entry under that key...
 278     (dolist (val (cdr-safe (assq tr entry)))
 279       (let* ((value-keys (registry-lookup-secondary-value db tr val)))
 280         (pushnew key value-keys :test 'equal)
 281         (registry-lookup-secondary-value db tr val value-keys))))
 282   entry)
 283
 284 (defmethod registry-reindex ((db registry-db))
 285   "Rebuild the secondary indices of registry-db THIS."
 286   (let ((count 0)
 287         (expected (* (length (oref db :tracked)) (registry-size db))))
 288     (dolist (tr (oref db :tracked))
 289       (let (values)
 290         (maphash
 291          (lambda (key v)
 292            (incf count)
 293            (when (and (< 0 expected)
 294                       (= 0 (mod count 1000)))
 295              (message "reindexing: %d of %d (%.2f%%)"
 296                       count expected (/ (* 100 count) expected)))
 297            (dolist (val (cdr-safe (assq tr v)))
 298              (let* ((value-keys (registry-lookup-secondary-value db tr val)))
 299                (push key value-keys)
 300                (registry-lookup-secondary-value db tr val value-keys))))
 301          (oref db :data))))))
 302
 303 (defmethod registry-prune ((db registry-db) &optional sortfun)
 304   "Prunes the registry-db object THIS.
 305 Removes only entries without the :precious keys if it can,
 306 then removes oldest entries first.
 307 Returns the number of deleted entries.
 308 If SORTFUN is given, tries to keep entries that sort *higher*.
 309 SORTFUN is passed only the two keys so it must look them up directly."
 310   (dolist (collector '(registry-prune-soft-candidates
 311                        registry-prune-hard-candidates))
 312     (let* ((size (registry-size db))
 313            (collected (funcall collector db))
 314            (limit (nth 0 collected))
 315            (candidates (nth 1 collected))
 316            ;; sort the candidates if SORTFUN was given
 317            (candidates (if sortfun (sort candidates sortfun) candidates))
 318            (candidates-count (length candidates))
 319            ;; are we over max-soft?
 320            (prune-needed (> size limit)))
 321
 322       ;; while we have more candidates than we need to remove...
 323       (while (and (> candidates-count (- size limit)) candidates)
 324         (decf candidates-count)
 325         (setq candidates (cdr candidates)))
 326
 327       (registry-delete db candidates nil)
 328       (length candidates))))
 329
 330 (defmethod registry-prune-soft-candidates ((db registry-db))
 331   "Collects pruning candidates from the registry-db object THIS.
 332 Proposes only entries without the :precious keys."
 333   (let* ((precious (oref db :precious))
 334          (precious-p (lambda (entry-key)
 335                        (cdr (memq (car entry-key) precious))))
 336          (data (oref db :data))
 337          (limit (oref db :max-soft))
 338          (candidates (loop for k being the hash-keys of data
 339                            using (hash-values v)
 340                            when (notany precious-p v)
 341                            collect k)))
 342     (list limit candidates)))
 343
 344 (defmethod registry-prune-hard-candidates ((db registry-db))
 345   "Collects pruning candidates from the registry-db object THIS.
 346 Proposes any entries over the max-hard limit minus size * prune-factor."
 347   (let* ((data (oref db :data))
 348          ;; prune to (size * prune-factor) below the max-hard limit so
 349          ;; we're not pruning all the time
 350          (limit (max 0 (- (oref db :max-hard)
 351                           (* (registry-size db) (oref db :prune-factor)))))
 352          (candidates (loop for k being the hash-keys of data
 353                            collect k)))
 354     (list limit candidates)))
 355
 356 (provide 'registry)
 357 ;;; registry.el ends here