src/backend.lisp

   1 (uiop:define-package #:lw2.backend
   2   (:use #:cl #:sb-thread #:flexi-streams #:alexandria #:iterate #:lw2-viewer.config #:lw2.sites #:lw2.context #:lw2.graphql #:lw2.lmdb
   3         #:lw2.utils #:lw2.hash-utils #:lw2.backend-modules #:lw2.schema-type #:lw2.conditions #:lw2.web-push)
   4   (:import-from #:collectors #:with-collector)
   5   (:import-from #:lw2.user-context #:*current-auth-token*)
   6   (:reexport #:lw2.backend-modules)
   7   (:export #:*use-alignment-forum*
   8            #:*graphql-debug-output*
   9            #:*revalidate-default* #:*force-revalidate-default*
  10            #:*messages-index-fields*
  11            #:*notifications-base-terms*
  12            #:start-background-loader #:stop-background-loader #:background-loader-running-p
  13            #:call-with-http-response
  14            #:forwarded-header #:backend-request-headers
  15            #:lw2-graphql-query #:lw2-query-string* #:lw2-query-string
  16            #:lw2-graphql-query-map #:lw2-graphql-query-multi
  17            #:signal-lw2-errors
  18            #:earliest-post-time
  19            #:flatten-shortform-comments #:get-shortform-votes
  20            #:get-tag-posts
  21            #:get-post-tag-votes #:get-tag-post-votes
  22            #:get-slug-tagid
  23            #:get-posts-index #:get-posts-json #:get-post-body #:get-post-vote #:get-post-comments #:get-post-answers
  24            #:get-post-comments-votes
  25            #:get-tag-comments-votes
  26            #:get-recent-comments #:get-recent-comments-json
  27            #:get-collection
  28            #:sequence-post-ids #:get-sequence #:get-post-sequence-ids #:get-sequence-post
  29            #:get-conversation-messages
  30            #:markdown-source
  31            #:get-user
  32            #:get-notifications #:check-notifications
  33            #:mark-comment-replied #:check-comment-replied
  34            #:lw2-search-query #:get-post-title #:get-post-slug #:get-slug-postid #:get-username #:get-user-full-name #:get-user-slug
  35            #:do-wl-rest-mutate #:do-wl-rest-query #:do-wl-create-tag)
  36   (:recycle #:lw2-viewer)
  37   (:unintern #:get-posts #:make-posts-list-query #:define-backend-fields
  38              #:*posts-index-fields* #:posts-index-fields #:post-body-fields
  39              #:*comments-index-fields* #:comments-index-fields
  40              #:*post-comments-fields* #:post-comments-fields
  41              #:define-index-fields #:decode-graphql-json
  42              #:lw2-graphql-query-noparse #:lw2-graphql-query-streamparse
  43              #:*cookie-jar*
  44              #:with-connection-pool #:call-with-connection-pool))
  45
  46 (in-package #:lw2.backend)
  47
  48 ;; Dexador settings required for the system to work properly.
  49 (setf dex:*default-connect-timeout* nil
  50       dex:*default-read-timeout* nil
  51       dex:*use-connection-pool* nil)
  52
  53 (defvar *use-alignment-forum* nil)
  54
  55 (defvar *graphql-debug-output* nil)
  56
  57 (defvar *revalidate-default* t)
  58 (defvar *force-revalidate-default* nil)
  59
  60 (defparameter *messages-index-fields* '(:--id :user-id :created-at (:contents :html) (:conversation :--id :title) :----typename))
  61 (defparameter *user-fields* '(:--id :slug :display-name :karma))
  62
  63 (defparameter *notifications-base-terms* (alist :view "userNotifications" :created-at :null :viewed :null))
  64
  65 (defun request-fields (query-type return-type context)
  66   "Returns the desired fields for a given type of request."
  67   (case return-type
  68     (:total nil)
  69     (t
  70      (with-collector (col)
  71        (let ((backend *current-backend*)
  72              (schema-type (find-schema-type query-type))
  73              (added (make-hash-table :test 'eq)))
  74          (dolist (field (cdr (assoc :fields schema-type)) (col))
  75            (destructuring-bind (field-name field-type &key alias backend-type graphql-ignore subfields ((:context field-context)) context-not &allow-other-keys) field
  76              (declare (ignore field-type))
  77              (when (and (not (gethash field-name added))
  78                         (not graphql-ignore)
  79                         (or (not backend-type) (typep backend backend-type))
  80                         (or (not field-context) (eq context field-context))
  81                         (or (not context-not) (not (eq context context-not))))
  82                (setf (gethash field-name added) t)
  83                (col
  84                 (let ((result-name (or alias field-name)))
  85                   (if subfields
  86                       (list* result-name subfields)
  87                       result-name)))))))))))
  88
  89 (define-backend-function user-fields ()
  90   (backend-lw2-legacy (load-time-value *user-fields*))
  91   (backend-lw2-modernized (append (call-next-method) '(:groups :deleted :html-bio)))
  92   (backend-alignment-forum (append (call-next-method) '(:af-karma :full-name))))
  93
  94 (define-cache-database 'backend-lw2-legacy
  95     "index-json"
  96     "post-comments-json" "post-comments-json-meta" "post-answers-json" "post-answers-json-meta"
  97     "post-body-json" "post-body-json-meta"
  98     "sequence-json" "sequence-json-meta" "post-sequence"
  99     "user-json" "user-json-meta"
 100     "user-page-items" "user-page-items-meta")
 101
 102 (define-cache-database 'backend-lw2-modernized
 103     "user-deleted")
 104
 105 (define-backend-function comments-list-to-graphql-json (comments-list)
 106   (backend-lw2-legacy
 107    (json:encode-json-to-string
 108     (plist-hash-table (list :data (plist-hash-table (list :*comments-list comments-list))))))
 109   (backend-lw2-modernized
 110    (json:encode-json-to-string
 111     (plist-hash-table (list :data (plist-hash-table (list :*comments-list (plist-hash-table (list :results comments-list)))))))))
 112
 113 (defun do-graphql-debug (query)
 114   (when *graphql-debug-output*
 115     (format *graphql-debug-output* "~&GraphQL query: ~A~%" query)))
 116
 117 (defmacro with-retrying ((maybe-retry-fn-name &key retries before-maybe-retry before-retry) &body body)
 118   (with-gensyms (remaining-retries retry)
 119     `(let ((,remaining-retries ,retries))
 120        (tagbody ,retry
 121           (labels ((,maybe-retry-fn-name ()
 122                      ,before-maybe-retry
 123                      (when (> ,remaining-retries 0)
 124                        (decf ,remaining-retries)
 125                        ,before-retry
 126                        (go ,retry))))
 127             ,@body)))))
 128
 129 (defun force-close (stream)
 130   (ignore-errors (close stream :abort t)))
 131
 132 (sb-ext:defglobal *connection-pool* (make-hash-table :test 'equal))
 133 (sb-ext:defglobal *connection-pool-lock* (sb-thread:make-mutex :name "*connection-pool-lock*"))
 134
 135 (defun connection-push (dest connection)
 136   (let ((connection-pool *connection-pool*)
 137         old-connection)
 138     (sb-thread:with-mutex (*connection-pool-lock*)
 139       (let ((vector (or (gethash dest connection-pool)
 140                         (setf (gethash dest connection-pool)
 141                               (make-array 4 :fill-pointer 0)))))
 142         (unless (vector-push connection vector)
 143           (setf old-connection (vector-pop vector))
 144           (vector-push connection vector))))
 145     (when old-connection
 146       (force-close old-connection))))
 147
 148 (defun connection-pop (dest)
 149   (let ((connection-pool *connection-pool*))
 150     (sb-thread:with-mutex (*connection-pool-lock*)
 151       (when-let (vector (gethash dest connection-pool))
 152                 (when (> (fill-pointer vector) 0)
 153                   (vector-pop vector))))))
 154
 155 (eval-when (:compile-toplevel :load-toplevel :execute)
 156   (defstruct (token-bucket (:constructor %make-token-bucket))
 157     (tokens internal-time-units-per-second :type fixnum)
 158     (base-cost internal-time-units-per-second :type fixnum)
 159     (last-update (get-internal-real-time) :type fixnum)
 160     (tokens-per-unit 1 :type fixnum)
 161     (token-limit internal-time-units-per-second :type fixnum))
 162
 163   (defun make-token-bucket (&key rate burst (fill-ratio 1.0))
 164     (let* ((scaled-rate (rationalize (/ internal-time-units-per-second rate)))
 165            (base-cost (numerator scaled-rate))
 166            (tokens-per-unit (denominator scaled-rate))
 167            (token-limit (* base-cost burst)))
 168       (%make-token-bucket
 169        :base-cost base-cost
 170        :tokens-per-unit tokens-per-unit
 171        :token-limit token-limit
 172        :tokens (round (* token-limit fill-ratio))))))
 173
 174 (defun token-bucket-decrement (token-bucket n &optional with-punishment)
 175   (let* ((time (get-internal-real-time))
 176          (tpu (token-bucket-tokens-per-unit token-bucket))
 177          (limit (token-bucket-token-limit token-bucket))
 178          (cost (round (* n (token-bucket-base-cost token-bucket))))
 179          (max-increment (+ limit cost))
 180          (max-timediff (ceiling max-increment tpu))
 181          (increment 0)
 182          (result nil))
 183     (declare (type (and fixnum (integer 0)) time)
 184              (type (unsigned-byte 32) limit cost max-increment increment)
 185              (type (integer 1 10000000) tpu))
 186     (sb-ext:atomic-update (token-bucket-last-update token-bucket)
 187                           (lambda (previous)
 188                             (declare (type (and fixnum (integer 0)) previous))
 189                             (if (> (- time max-timediff) previous)
 190                                 (setf increment max-increment)
 191                                 (let ((timediff (- time (min previous time))))
 192                                   (declare (type (unsigned-byte 32) timediff))
 193                                   (setf increment (* timediff tpu))))
 194                             (max previous time)))
 195     (sb-ext:atomic-update (token-bucket-tokens token-bucket)
 196                           (lambda (previous)
 197                             (declare (type (signed-byte 32) previous))
 198                             (let* ((new-refill (+ previous increment))
 199                                    (new (- new-refill cost)))
 200                               (setf result (> new 0))
 201                               (if (or result with-punishment)
 202                                   (min new limit)
 203                                   (max (- limit) (min new-refill limit))))))
 204     result))
 205
 206 (defun parse-ipv4 (string)
 207   (let ((l (map 'list #'parse-integer
 208                 (split-sequence:split-sequence #\. string))))
 209     (loop with res = 0
 210        for n in l
 211        do (setf res (+ n (ash res 8)))
 212        finally (return res))))
 213
 214 (defparameter *rate-limit-cost-factor* 1)
 215
 216 (sb-ext:defglobal *global-token-bucket* (make-token-bucket :rate 3 :burst 180))
 217
 218 (defun check-rate-limit ()
 219   (or (token-bucket-decrement *global-token-bucket* *rate-limit-cost-factor*)
 220       (error "Rate limit exceeded. Try again later.")))
 221
 222 (defun call-with-http-response (fn uri-string &rest args &key &allow-other-keys)
 223   (check-rate-limit)
 224   (let* ((uri (quri:uri uri-string))
 225          (uri-dest (concatenate 'string (quri:uri-host uri) ":" (format nil "~d" (quri:uri-port uri))))
 226          (stream (connection-pop uri-dest)))
 227     (let (response status-code headers response-uri new-stream success)
 228       (with-retrying (maybe-retry :retries 3
 229                                   :before-retry (sleep 0.2))
 230         (unwind-protect
 231              (handler-bind (((or dex:http-request-failed usocket:ns-condition usocket:socket-condition)
 232                              (lambda (condition)
 233                                (if-let ((r (find-restart 'dex:ignore-and-continue condition))
 234                                         (ct (gethash "content-type" (dex:response-headers condition))))
 235                                    (if (ppcre:scan "^application/json" ct)
 236                                        (invoke-restart r)
 237                                        (maybe-retry))))))
 238                (setf (values response status-code headers response-uri new-stream)
 239                      (apply 'dex:request uri :use-connection-pool nil :keep-alive t :stream stream args))
 240                (unless (eq stream new-stream)
 241                  (when stream (force-close stream))
 242                  (setf stream new-stream
 243                        new-stream nil))
 244                (when (<= 500 status-code 599)
 245                  (maybe-retry)
 246                  (error 'lw2-connection-error :message (format nil "HTTP status ~A" status-code)))
 247                (setf success t))
 248           (when (not success)
 249             (when (streamp response)
 250               (force-close response))
 251             (when stream
 252               (force-close stream))
 253             (setf stream nil))))
 254       (unwind-protect
 255            (funcall fn response)
 256         (when (streamp response)
 257           (close response))
 258         (when stream ; the connection is reusable
 259           (connection-push uri-dest stream))))))
 260
 261 (defun forwarded-header ()
 262   (let ((addr (and (boundp 'hunchentoot:*request*) (hunchentoot:real-remote-addr))))
 263     (list-cond (addr "X-Forwarded-For" addr))))
 264
 265 (defun signal-lw2-errors (errors)
 266   (loop for error in errors
 267         do (let ((message (cdr (assoc :message error)))
 268                  (path (cdr (assoc :path error))))
 269              (unless (and path (> (length path) 1))
 270                (cond
 271                  ((search "document_not_found" message) (error 'lw2-not-found-error))
 272                  ((search "app.missing_document" message) (error 'lw2-not-found-error))
 273                  ((search "only visible to logged-in users" message) (error 'lw2-login-required-error))
 274                  ((search "not_allowed" message) (error 'lw2-not-allowed-error))
 275                  (t (error 'lw2-unknown-error :message message)))))))
 276
 277 (define-backend-function earliest-post-time ()
 278   (backend-lw2 (load-time-value (local-time:parse-timestring "2005-01-01")))
 279   (backend-ea-forum (load-time-value (local-time:parse-timestring "2011-11-24"))))
 280
 281 (define-backend-function fixup-lw2-return-value (value)
 282   (backend-base
 283    value)
 284   (backend-lw2-modernized
 285    (values-list
 286     (map 'list
 287          (lambda (x)
 288            (if (member (car x) '(:result :results :total-count))
 289                (cdr x)
 290                x))
 291          value)))
 292   (backend-accordius
 293    value))
 294
 295 (define-backend-function deserialize-query-result (result-source)
 296   (backend-base
 297    (let ((string-source (typecase result-source
 298                           (string
 299                            result-source)
 300                           (vector
 301                            (flexi-streams:make-in-memory-input-stream result-source))
 302                           (stream
 303                            (ensure-character-stream result-source)))))
 304      (json:decode-json-from-source string-source))))
 305
 306 (define-backend-function postprocess-query-result (result)
 307   (backend-base
 308    result)
 309   (backend-lw2-legacy
 310    (signal-lw2-errors (cdr (assoc :errors result)))
 311    (fixup-lw2-return-value (cdadr (assoc :data result)))))
 312
 313 (define-backend-function decode-query-result (result-source)
 314   (backend-base
 315    (postprocess-query-result
 316     (deserialize-query-result result-source))))
 317
 318 (defmethod graphql-uri ((backend backend-alignment-forum))
 319   (if *use-alignment-forum*
 320       "https://www.alignmentforum.org/graphql"
 321       (call-next-method)))
 322
 323 (define-backend-function backend-request-headers (auth-token forwarded)
 324   (backend-websocket-login
 325    (list-cond* (auth-token :authorization auth-token)
 326                (call-next-method)))
 327   (backend-passport-js-login
 328    (list-cond* (auth-token :cookie (concatenate 'string "loginToken=" auth-token))
 329                (call-next-method)))
 330   (backend-graphql
 331    (alist* :content-type "application/json"
 332            (if forwarded (forwarded-header)))))
 333
 334 (define-backend-function call-with-backend-response (fn query &key return-type auth-token)
 335   (backend-graphql
 336    (call-with-http-response
 337     fn
 338     (graphql-uri *current-backend*)
 339     :method :post
 340     :headers (backend-request-headers auth-token nil)
 341     :content (dynamic-let ((q (alist :query query))) (json:encode-json-to-string q))
 342     :want-stream (not return-type))))
 343
 344 (define-backend-function lw2-graphql-query (query &key auth-token return-type (decoder 'decode-query-result))
 345   (backend-base
 346    (do-graphql-debug query)
 347    (call-with-backend-response
 348     (ecase return-type
 349       ((nil) decoder)
 350       (:string #'identity)
 351       (:both (lambda (string) (values (funcall decoder string) string))))
 352     query
 353     :return-type return-type
 354     :auth-token auth-token)))
 355
 356 (defun lw2-graphql-query-map (fn data &key auth-token postprocess)
 357   (multiple-value-bind (map-values queries)
 358     (loop for d in data
 359           as out-values = (multiple-value-list (funcall fn d))
 360           as (out passthrough-p) = out-values
 361           collect out-values into map-values
 362           when (not passthrough-p) collect out into queries
 363           finally (return (values map-values queries)))
 364     (let* ((query-string
 365              (with-output-to-string (stream)
 366                (format stream "{")
 367                (loop for n from 0
 368                      for q in queries
 369                      do (format stream "g~6,'0D:~A " n q))
 370                (format stream "}")))
 371            (query-result-data (when queries (lw2-graphql-query query-string :decoder 'deserialize-query-result :auth-token auth-token)))
 372            (errors (cdr (assoc :errors query-result-data))))
 373       (signal-lw2-errors errors)
 374       (values
 375         (loop as results = (sort (cdr (assoc :data query-result-data)) #'string< :key #'car) then (if passthrough-p results (rest results))
 376               for (out passthrough-p) in map-values
 377               as result-data-cell = (first results)
 378                       as result-data = (if passthrough-p out (fixup-lw2-return-value (cdr result-data-cell)))
 379                       for input-data in data
 380                       collect (if postprocess (funcall postprocess input-data result-data) result-data))
 381                 errors))))
 382
 383 (defun lw2-graphql-query-multi (query-list &key auth-token)
 384   (values-list (lw2-graphql-query-map #'identity query-list :auth-token auth-token)))
 385
 386 (defvar *background-cache-update-threads* (make-hash-table :test 'equal
 387                                                            :weakness :value
 388                                                            :synchronized t))
 389
 390 (defun cache-update (cache-db key data)
 391   (let ((meta-db (format nil "~A-meta" cache-db))
 392         (new-hash (hash-string data))
 393         (current-time (get-unix-time)))
 394     (with-cache-transaction
 395       (let* ((metadata (cache-get meta-db key :value-type :lisp))
 396              (same-data (equalp new-hash (cdr (assoc :city-128-hash metadata))))
 397              (last-mod (if same-data
 398                            (or (cdr (assoc :last-modified metadata)) current-time)
 399                            current-time)))
 400         (cache-put meta-db key (alist :last-checked current-time :last-modified last-mod :city-128-hash new-hash) :value-type :lisp)
 401         (unless same-data
 402           (cache-put cache-db key data))))))
 403
 404 (defun cache-mark-stale (cache-db key)
 405   (let ((meta-db (format nil "~A-meta" cache-db))
 406         (current-time (get-unix-time)))
 407     (with-cache-transaction
 408         (let* ((metadata (cache-get meta-db key :value-type :lisp))
 409                (metadata (alist* :last-modified current-time (delete :last-modified metadata :key #'car))))
 410           (cache-put meta-db key metadata :value-type :lisp)))))
 411
 412 (declaim (type (and fixnum (integer 1)) *cache-stale-factor* *cache-skip-factor*))
 413 (defparameter *cache-stale-factor* 100)
 414 (defparameter *cache-skip-factor* 5000)
 415
 416 (defun cache-is-fresh (cache-db key)
 417   (let ((metadata (cache-get (format nil "~A-meta" cache-db) key :value-type :lisp))
 418         (current-time (get-unix-time)))
 419     (if-let ((last-mod (cdr (assoc :last-modified metadata)))
 420              (last-checked (cdr (assoc :last-checked metadata))))
 421             (let ((unmodified-time (- last-checked last-mod))
 422                   (last-checked-time (- current-time last-checked)))
 423               (if (> unmodified-time (* *cache-skip-factor* last-checked-time))
 424                   :skip
 425                   (> unmodified-time (* *cache-stale-factor* last-checked-time)))))))
 426
 427 (defgeneric run-query (query)
 428   (:method ((query string))
 429     (lw2-graphql-query query :return-type :string))
 430   (:method ((query function))
 431     (funcall query)))
 432
 433 (declaim (inline make-thread-with-current-backend))
 434
 435 (defun make-thread-with-current-backend (fn &rest args)
 436   (let ((current-backend *current-backend*))
 437     (apply #'sb-thread:make-thread
 438       (lambda ()
 439         (let ((*current-backend* current-backend))
 440           (funcall fn)))
 441       args)))
 442
 443 (defun ensure-cache-update-thread (query cache-db cache-key)
 444   (let ((key (format nil "~A-~A" cache-db cache-key)))
 445     (labels ((background-fn ()
 446                (unwind-protect
 447                     (multiple-value-bind (value error)
 448                         (log-and-ignore-errors
 449                          (sb-sys:with-deadline (:seconds 60)
 450                            (nth-value 0
 451                                       (cache-update cache-db cache-key (run-query query)))))
 452                       (or value error))
 453                  (remhash key *background-cache-update-threads*))))
 454       (sb-ext:with-locked-hash-table (*background-cache-update-threads*)
 455                                      (let ((thread (gethash key *background-cache-update-threads*)))
 456                                        (if thread thread
 457                                          (setf (gethash key *background-cache-update-threads*)
 458                                                (make-thread-with-current-backend #'background-fn :name "background cache update"))))))))
 459
 460 (define-backend-function lw2-graphql-query-timeout-cached (query cache-db cache-key &key (decoder 'decode-query-result)
 461                                                                  (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*))
 462   (backend-base
 463    (multiple-value-bind (cached-result is-fresh) (with-cache-readonly-transaction
 464                                                      (values (cache-exists cache-db cache-key)
 465                                                              (cache-is-fresh cache-db cache-key)))
 466      (labels ((get-cached-result ()
 467                 (with-cache-readonly-transaction (funcall decoder (cache-get cache-db cache-key :return-type 'binary-stream)))))
 468        (if (and cached-result (or (not revalidate)
 469                                   (and (not force-revalidate) (eq is-fresh :skip))))
 470            (get-cached-result)
 471            (let ((timeout (if cached-result
 472                               (if force-revalidate nil 3)
 473                               nil))
 474                  (thread (ensure-cache-update-thread query cache-db cache-key)))
 475              (block retrieve-result
 476                (if (and cached-result (if force-revalidate (not revalidate) (or is-fresh (not revalidate))))
 477                    (get-cached-result)
 478                    (handler-bind
 479                        ((fatal-error (lambda (c)
 480                                        (declare (ignore c))
 481                                        (if cached-result
 482                                            (return-from retrieve-result (get-cached-result))))))
 483                      (let ((new-result (sb-thread:join-thread thread :timeout timeout)))
 484                        (typecase new-result
 485                          (condition (error new-result))
 486                          (t (funcall decoder new-result)))))))))))))
 487
 488 (define-backend-function lw2-query-string* (query-type return-type args &key context fields with-total))
 489
 490 (define-backend-operation lw2-query-string* backend-lw2-legacy (query-type return-type args &key context (fields (request-fields query-type return-type context)) with-total)
 491   (declare (ignore with-total))
 492   (labels ((lisp-to-lw2-case (x) (json:lisp-to-camel-case (format nil "*~A" x))))
 493     (graphql-query-string*
 494      (concatenate 'string
 495                   (lisp-to-lw2-case query-type)
 496                   "s"
 497                   (lisp-to-lw2-case return-type))
 498      (if (eq return-type :single)
 499          args
 500          (alist :terms args))
 501      fields)))
 502
 503 (define-backend-operation lw2-query-string* backend-lw2-modernized (query-type return-type args &key context (fields (request-fields query-type return-type context)) with-total)
 504   (graphql-query-string*
 505     (if (eq return-type :single)
 506         (json:lisp-to-camel-case (string query-type))
 507         (concatenate 'string (json:lisp-to-camel-case (string query-type)) "s"))
 508     (alist :input (case return-type
 509                     (:single (alist :selector args))
 510                     (:list (alist :enable-total with-total :terms args))
 511                     (:total (alist :enable-total t :terms args))))
 512     (case return-type
 513       (:total '(:total-count))
 514       (:list (list-cond (t :results fields)
 515                         (with-total :total-count)))
 516       (:single (alist :result fields)))))
 517
 518 (define-backend-function lw2-query-string (query-type return-type args &key context fields with-total))
 519
 520 (define-backend-operation lw2-query-string backend-lw2-legacy (query-type return-type args &rest rest &key context fields with-total)
 521   (declare (ignore context fields with-total))
 522   (format nil "{~A}" (apply 'lw2-query-string* query-type return-type args rest)))
 523
 524 (define-backend-function lw2-query-list-limit-workaround (query-type terms &rest rest &key fields context auth-token)
 525   (backend-graphql
 526    (declare (ignore fields context))
 527    (let (items-list)
 528      (loop for offset from 0 by 500
 529         as items-next = (lw2-graphql-query (apply 'lw2-query-string query-type :list (alist* :limit 500 :offset offset terms) (filter-plist rest :fields :context))
 530                                            :auth-token auth-token)
 531         as length = (length items-next)
 532         do (setf items-list (nconc items-list items-next))
 533         while (>= length 500))
 534      items-list))
 535   (backend-accordius
 536    (declare (ignore fields context))
 537    (lw2-graphql-query (apply 'lw2-query-string query-type :list terms (filter-plist rest :fields :context)) :auth-token auth-token)))
 538
 539 (defun get-cached-index-query (cache-id query)
 540   (labels ((query-and-put ()
 541              (let* ((result (lw2-graphql-query query :return-type :string))
 542                     (decoded-result (multiple-value-list (decode-query-result result))))
 543                (cache-put "index-json" cache-id result)
 544                (values-list decoded-result)))
 545            (get-cached-result ()
 546              (with-cache-readonly-transaction (decode-query-result (cache-get "index-json" cache-id :return-type 'binary-stream)))))
 547     (let ((cached-result (cache-get "index-json" cache-id :return-type 'existence)))
 548       (if (and cached-result (background-loader-ready-p))
 549           (get-cached-result)
 550           (if cached-result
 551               (handler-case
 552                   (query-and-put)
 553                 (t () (get-cached-result)))
 554               (query-and-put))))))
 555
 556 (define-backend-function get-posts-index-query-terms (&key view (sort "new") (limit 21) offset before after karma-threshold &allow-other-keys)
 557   (backend-lw2-legacy
 558    (let ((sort-key (alexandria:switch (sort :test #'string=)
 559                                       ("new" "new")
 560                                       ("hot" "magic")
 561                                       ("active" "recentComments")
 562                                       ("top" "top")
 563                                       ("old" "old"))))
 564      (multiple-value-bind (view-terms cache-key)
 565          (alexandria:switch (view :test #'string=)
 566                             ("featured" (alist :sorted-by sort-key :filter "curated"))
 567                             ("all" (alist :sorted-by sort-key :filter "all"))
 568                             ("alignment-forum" (alist :sorted-by sort-key :af t))
 569                             ("questions" (alist :sorted-by sort-key :filter "questions"))
 570                             ("events" (alist :sorted-by sort-key :filter "events"))
 571                             ("nominations" (alist :view "nominations2019"))
 572                             ("reviews" (alist :view "reviews2019"))
 573                             (t (values
 574                                 (alist :sorted-by sort-key :filter "frontpage")
 575                                 (if (not (or (string/= sort "new") (/= limit 21) offset before after karma-threshold)) "new-not-meta"))))
 576        (let ((terms
 577               (alist-without-null* :before before
 578                                    :after after
 579                                    :limit limit
 580                                    :offset offset
 581                                    :karma-threshold karma-threshold
 582                                    view-terms)))
 583          (values terms cache-key))))))
 584
 585 (define-backend-operation get-posts-index-query-terms backend-lw2-tags :around (&key hide-tags &allow-other-keys)
 586   (multiple-value-bind (query-terms cache-key) (call-next-method)
 587     (if hide-tags
 588         (values (acons :filter-settings (alist :tags (list* :list (map 'list (lambda (tagid) (alist :tag-id tagid :filter-mode "Hidden"))
 589                                                                        hide-tags)))
 590                        query-terms)
 591                 nil)
 592         (values query-terms cache-key))))
 593
 594 (define-backend-function get-posts-index-query-string (&rest args &key &allow-other-keys)
 595   (backend-lw2-legacy
 596    (declare (dynamic-extent args))
 597    (multiple-value-bind (query-terms cache-key)
 598        (apply #'%get-posts-index-query-terms backend args)
 599      (values (lw2-query-string :post :list query-terms)
 600              cache-key))))
 601
 602 (define-backend-function get-posts-index (&rest args &key &allow-other-keys)
 603   (backend-lw2-legacy
 604    (declare (dynamic-extent args))
 605    (multiple-value-bind (query-string cache-key)
 606        (apply #'%get-posts-index-query-string backend args)
 607      (if cache-key
 608          (get-cached-index-query cache-key query-string)
 609          (lw2-graphql-query query-string)))))
 610
 611 (define-backend-operation get-posts-index backend-lw2-tags :around (&rest args &key hide-tags offset (limit 21) &allow-other-keys)
 612   ;; Workaround for https://github.com/LessWrong2/Lesswrong2/issues/3099
 613   (declare (dynamic-extent args))
 614   (if hide-tags
 615       (let ((offset (or offset 0)))
 616         (subseq
 617          (apply #'call-next-method backend :offset 0 :limit (+ limit offset) args)
 618          offset))
 619       (call-next-method)))
 620
 621 (defun get-posts-json ()
 622   (lw2-graphql-query (get-posts-index-query-string) :return-type :string))
 623
 624 (defun get-recent-comments (&key with-total)
 625   (get-cached-index-query "recent-comments" (lw2-query-string :comment :list '((:view . "allRecentComments") (:limit . 20)) :context :index :with-total with-total)))
 626
 627 (defun get-recent-comments-json ()
 628   (lw2-graphql-query (lw2-query-string :comment :list '((:view . "allRecentComments") (:limit . 20)) :context :index) :return-type :string))
 629
 630 (defun process-vote-result (res)
 631   (alist-bind ((id (or null simple-string) :--id)
 632                current-user-votes
 633                current-user-vote
 634                current-user-extended-vote)
 635               res
 636               (let ((karma-vote (or (nonempty-string current-user-vote)
 637                                     (cdr (assoc :vote-type (first current-user-votes))))))
 638                 (values (list-cond* (karma-vote :karma karma-vote)
 639                                     current-user-extended-vote)
 640                         id))))
 641
 642 (defun process-votes-result (res)
 643   (let ((hash (make-hash-table)))
 644     (dolist (v res hash)
 645       (multiple-value-bind (vote id) (process-vote-result v)
 646         (when vote
 647           (setf (gethash id hash) vote))))))
 648
 649 (defun flatten-shortform-comments (comments)
 650   (let ((output comments))
 651     (loop for comment in comments do
 652          (setf output (append (cdr (assoc :latest-children comment)) output)))
 653     output))
 654
 655 (defun get-shortform-votes (auth-token &key (offset 0) (limit 20))
 656   (process-votes-result
 657    (flatten-shortform-comments
 658     (lw2-graphql-query (lw2-query-string :comment :list (alist :view "shortform" :offset offset :limit limit)
 659                                          :fields '(:--id :current-user-vote :current-user-extended-vote (:latest-children :--id :current-user-vote :current-user-extended-vote)))
 660                        :auth-token auth-token))))
 661
 662 (defun get-post-vote (post-id auth-token)
 663   (process-vote-result (lw2-graphql-query (lw2-query-string :post :single (alist :document-id post-id) :fields '(:--id :current-user-vote :current-user-extended-vote)) :auth-token auth-token)))
 664
 665 (define-cache-database 'backend-lw2-tags "tag-posts" "tag-posts-meta" "post-tags" "post-tags-meta")
 666
 667 (define-backend-function get-tag-posts (slug &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*))
 668   (backend-base (declare (ignore revalidate force-revalidate)) nil)
 669   (backend-lw2-tags
 670    (let* ((tagid (get-slug-tagid slug))
 671           (query-fn (lambda ()
 672                       (comments-list-to-graphql-json
 673                        (lw2-query-list-limit-workaround
 674                         :tag-rel
 675                         (alist :view "postsWithTag" :tag-id tagid)
 676                         :fields (list (list* :post (request-fields :post :list :index))))))))
 677      (iter
 678       (for x in (lw2-graphql-query-timeout-cached query-fn "tag-posts" tagid :revalidate revalidate :force-revalidate force-revalidate))
 679       (when-let (post (cdr (assoc :post x)))
 680         (collect post))))))
 681
 682 (define-backend-function get-tag-post-votes (tag-id auth-token)
 683   (backend-base (progn tag-id auth-token nil))
 684   (backend-lw2-tags
 685    (process-votes-result
 686     (map 'list #'cdr
 687          (lw2-query-list-limit-workaround
 688           :tag-rel
 689           (alist :view "postsWithTag" :tag-id tag-id)
 690           :fields '(:--id :current-user-vote :current-user-extended-vote)
 691           :auth-token auth-token)))))
 692
 693 (define-backend-function get-post-tags (post-id &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*))
 694   (backend-base (declare (ignore revalidate force-revalidate)) nil)
 695   (backend-lw2-tags
 696    (let ((query-string (lw2-query-string :tag-rel :list (alist :view "tagsOnPost" :post-id post-id) :fields '((:tag :name :slug)))))
 697      (lw2-graphql-query-timeout-cached query-string "post-tags" post-id :revalidate revalidate :force-revalidate force-revalidate))))
 698
 699 (define-backend-function get-post-tag-votes (post-id auth-token)
 700   (backend-base (progn post-id auth-token nil))
 701   (backend-lw2-tags
 702    (process-votes-result
 703     (lw2-graphql-query (lw2-query-string :tag-rel :list (alist :view "tagsOnPost" :post-id post-id) :fields '(:--id :current-user-vote :current-user-extended-vote))
 704                        :auth-token auth-token))))
 705
 706 (define-backend-function get-post-body (post-id &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*) auth-token)
 707   (backend-graphql
 708    (let ((query-string (lw2-query-string :post :single (alist :document-id post-id) :context :body)))
 709      (block nil
 710        (tagbody retry
 711           (handler-bind ((lw2-login-required-error (lambda (&rest args)
 712                                                      (declare (ignore args))
 713                                                      (let ((current-auth-token *current-auth-token*))
 714                                                        (when (and (not auth-token) current-auth-token)
 715                                                          (setf auth-token current-auth-token)
 716                                                          (go retry))))))
 717             (return
 718               (if auth-token
 719                   (lw2-graphql-query query-string :auth-token auth-token)
 720                   (lw2-graphql-query-timeout-cached query-string "post-body-json" post-id :revalidate revalidate :force-revalidate force-revalidate))))))))
 721   (backend-lw2-tags
 722    (declare (ignore auth-token))
 723    (acons :tags (get-post-tags post-id :revalidate revalidate :force-revalidate force-revalidate) (call-next-method)))
 724   (backend-magnum-crossposts
 725    (declare (ignore auth-token))
 726    (let ((post (call-next-method)))
 727      (alist-bind (is-crosspost hosted-here foreign-post-id) (cdr (assoc :fm-crosspost post))
 728        (cond ((not (and (backend-magnum-crosspost-site backend)
 729                         (not (boundp '*retrieve-crosspost*))
 730                         is-crosspost foreign-post-id))
 731               post)
 732              (:otherwise
 733               (let* ((*current-site* (find-site (backend-magnum-crosspost-site backend)))
 734                      (*current-backend* (site-backend *current-site*))
 735                      (*retrieve-crosspost* nil)
 736                      (foreign-post (get-post-body foreign-post-id :revalidate revalidate :force-revalidate force-revalidate))
 737                      (foreign-post-body (cdr (assoc :html-body foreign-post))))
 738                 (declare (special *retrieve-crosspost*))
 739                 (if foreign-post-body
 740                     (list-cond*
 741                      ((not hosted-here) :html-body foreign-post-body)
 742                      (t :foreign-post foreign-post)
 743                      post)
 744                     post))))))))
 745
 746 (defun get-post-comments-list (post-id view &rest rest &key auth-token parent-answer-id fields context)
 747   (declare (ignore fields context auth-token))
 748   (let ((terms (alist :view view :post-id post-id)))
 749     (when parent-answer-id
 750       (setf terms (acons :parent-answer-id parent-answer-id terms)))
 751     (apply 'lw2-query-list-limit-workaround :comment terms (filter-plist rest :fields :context :auth-token))))
 752
 753 (defun get-post-answer-replies (post-id answers &rest rest &key auth-token fields context)
 754   ;; todo: support more than 500 answers per question
 755   (declare (ignore fields context))
 756   (let* ((terms (alist :view "repliesToAnswer" :post-id post-id :limit 500))
 757          (result (lw2-graphql-query-map
 758                   #'identity
 759                   (mapcar (lambda (answer) (apply 'lw2-query-string* :comment :list
 760                                                   (acons :parent-answer-id (cdr (assoc :--id answer)) terms)
 761                                                   (filter-plist rest :fields :context)))
 762                           answers)
 763                   :auth-token auth-token)))
 764     (apply #'nconc result)))
 765
 766 (define-backend-function get-post-comments-votes (post-id auth-token)
 767   (backend-graphql
 768    (let ((fields '(:--id :current-user-vote :current-user-extended-vote)))
 769      (process-votes-result
 770       (get-post-comments-list post-id "postCommentsTop" :auth-token auth-token :fields fields))))
 771   (backend-q-and-a
 772    (let* ((fields '(:--id :current-user-vote :current-user-extended-vote))
 773           (answers (get-post-comments-list post-id "questionAnswers" :auth-token auth-token :fields fields)))
 774      (process-votes-result
 775       (nconc
 776        (get-post-comments-list post-id "postCommentsTop" :auth-token auth-token :fields fields)
 777        (get-post-answer-replies post-id answers :auth-token auth-token :fields fields)
 778        answers)))))
 779
 780 (define-backend-function get-tag-comments-votes (tag-id auth-token)
 781   (backend-lw2-tags-comments
 782    (process-votes-result (lw2-graphql-query (lw2-query-string :comment :list (alist :tag-id tag-id :view "tagDiscussionComments") :fields '(:--id :current-user-vote :current-user-extended-vote))
 783                                             :auth-token auth-token))))
 784
 785 (define-backend-function get-post-comments (post-id &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*))
 786   (backend-graphql
 787    (let ((fn (lambda ()
 788                (comments-list-to-graphql-json
 789                 (get-post-comments-list post-id "postCommentsTop")))))
 790      (lw2-graphql-query-timeout-cached fn "post-comments-json" post-id :revalidate revalidate :force-revalidate force-revalidate)))
 791   (backend-ea-forum
 792    ;; Work around bizarre parent comment bug in EA forum
 793    (declare (ignore revalidate force-revalidate))
 794    (let ((comments (call-next-method)))
 795      (dolist (c comments)
 796        (if-let (parent-id-cons (assoc :parent-comment-id c))
 797                (if (and (string= (cdr parent-id-cons) "rjgZaK8uzHG3jAu2p")
 798                         (not (string= post-id "h26Kx7uGfQfNewi7d")))
 799                    (setf (cdr parent-id-cons) nil))))
 800      comments)))
 801
 802 (defun get-post-answers (post-id &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*))
 803   (let ((fn (lambda ()
 804               (let ((answers (get-post-comments-list post-id "questionAnswers")))
 805                 (comments-list-to-graphql-json
 806                  (nconc
 807                   answers
 808                   (get-post-answer-replies post-id answers)))))))
 809     (lw2-graphql-query-timeout-cached fn "post-answers-json" post-id :revalidate revalidate :force-revalidate force-revalidate)))
 810
 811 (define-backend-function get-collection (collection-id)
 812   (backend-graphql
 813    (lw2-graphql-query
 814     (lw2-query-string :collection :single
 815                       (alist :document-id collection-id)
 816                       :fields `(:--id :title (:contents :html) :grid-image-id :----typename
 817                                       (:books :title :subtitle (:contents :html) :----typename
 818                                               (:sequences :title (:contents :html) :grid-image-id :----typename
 819                                                           (:chapters :title :subtitle :number (:contents :html) (:posts ,@(request-fields :post :list nil))))))))))
 820
 821 (defun sequence-iterate (sequence fn)
 822   (dolist (chapter (cdr (assoc :chapters sequence)))
 823     (dolist (post (cdr (assoc :posts chapter)))
 824       (funcall fn post))))
 825
 826 (defun sequence-post-ids (sequence)
 827   (with-collector (col)
 828     (sequence-iterate sequence
 829                       (lambda (post)
 830                         (col (cdr (assoc :--id post)))))
 831     (col)))
 832
 833 (defun get-sequence-post (sequence post-id)
 834   (sequence-iterate sequence
 835                     (lambda (post)
 836                       (when (string= (cdr (assoc :--id post)) post-id)
 837                         (return-from get-sequence-post post))))
 838   nil)
 839
 840 (define-backend-function get-sequence (sequence-id)
 841   (backend-graphql
 842    (let ((fn (lambda ()
 843                (multiple-value-bind (sequence sequence-json)
 844                    (lw2-graphql-query
 845                     (lw2-query-string :sequence :single
 846                                       (alist :document-id sequence-id)
 847                                       :fields `(:--id :title :created-at :user-id
 848                                                       (:contents :html)
 849                                                       (:chapters :title :subtitle :number (:contents :html) (:posts ,@(request-fields :post :list nil)))
 850                                                       :grid-image-id :----typename))
 851                     :return-type :both)
 852                  (let ((posts (sequence-post-ids sequence)))
 853                    (with-cache-transaction
 854                        (dolist (post-id posts)
 855                          (let ((old-seqs (cache-get "post-sequence" post-id :value-type :json)))
 856                            (unless (member sequence-id old-seqs :test #'string=)
 857                              (cache-put "post-sequence" post-id (cons sequence-id old-seqs) :value-type :json)))))
 858                    sequence-json)))))
 859      (lw2-graphql-query-timeout-cached fn "sequence-json" sequence-id))))
 860
 861 (define-backend-function get-post-sequence-ids (post-id)
 862   (backend-graphql
 863    (cache-get "post-sequence" post-id :value-type :json)))
 864
 865 (defun preload-sequences-cache ()
 866   (declare (optimize space (compilation-speed 2) (speed 0)))
 867   (let ((sequences (apply #'append
 868                           (loop for view in '("curatedSequences" "communitySequences")
 869                              collect (lw2-graphql-query (lw2-query-string :sequence :list (alist :view view) :fields '(:--id)))))))
 870     (dolist (sequence sequences)
 871       (get-sequence (cdr (assoc :--id sequence))))
 872     (format t "Retrieved ~A sequences." (length sequences)))
 873   (values))
 874
 875 (define-backend-function user-deleted (user-id &optional (status nil set))
 876   (backend-base
 877    (declare (ignore user-id status set))
 878    nil)
 879   (backend-lw2-modernized
 880    (if set
 881        (if status
 882            (cache-put "user-deleted" user-id "1")
 883            (cache-del "user-deleted" user-id))
 884        (cache-get "user-deleted" user-id :return-type 'existence))))
 885
 886 (define-backend-function get-user (user-identifier-type user-identifier &key (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*) auth-token)
 887   (backend-graphql
 888    (let* ((user-id (ccase user-identifier-type
 889                      (:user-id user-identifier)
 890                      (:user-slug (get-slug-userid user-identifier))))
 891           (query-string (lw2-query-string :user :single (alist :document-id user-id) :fields (list-cond* (auth-token :last-notifications-check) (user-fields))))
 892           (result (if auth-token
 893                       (lw2-graphql-query query-string :auth-token auth-token)
 894                       (lw2-graphql-query-timeout-cached query-string "user-json" user-id :revalidate revalidate :force-revalidate force-revalidate))))
 895      (alist-bind ((user-id (or simple-string null) :--id)
 896                   (display-name (or simple-string null))
 897                   (full-name (or simple-string null))
 898                   (slug (or simple-string null))
 899                   (deleted boolean))
 900                  result
 901                  (when user-id
 902          (with-cache-transaction
 903            (when display-name
 904              (cache-username user-id display-name))
 905            (when full-name
 906              (cache-user-full-name user-id full-name))
 907            (when slug
 908              (cache-user-slug user-id slug)
 909              (cache-slug-userid slug user-id))
 910            (user-deleted user-id deleted))))
 911      result)))
 912
 913 (define-backend-function get-notifications (&key user-id (offset 0) (limit 21) auth-token)
 914   (backend-lw2-legacy
 915    (lw2-graphql-query (lw2-query-string :notification :list
 916                                         (alist* :user-id user-id :limit limit :offset offset *notifications-base-terms*)
 917                                         :fields '(:--id :document-type :document-id :link :title :message :type :viewed))
 918                       :auth-token auth-token))
 919   (backend-lw2-modernized
 920    (declare (ignore user-id offset limit auth-token))
 921    (let ((*notifications-base-terms* (remove :null *notifications-base-terms* :key #'cdr)))
 922      (call-next-method))))
 923
 924 (define-backend-function check-notifications (user-id auth-token &key full since)
 925   (backend-lw2-legacy
 926    (multiple-value-bind (notifications user-info)
 927        (lw2-graphql-query-multi (list
 928                                  (lw2-query-string* :notification :list (alist* :user-id user-id :limit (if full 3 1) *notifications-base-terms*)
 929                                                     :fields (if full '(:--id :message :created-at) '(:created-at)))
 930                                  (lw2-query-string* :user :single (alist :document-id user-id) :fields '(:last-notifications-check)))
 931                                 :auth-token auth-token)
 932      (let ((last-check (or since
 933                            (let ((last-check-string (cdr (assoc :last-notifications-check user-info))))
 934                              (when (and (stringp last-check-string) (not (equal last-check-string "")))
 935                                (local-time:parse-timestring last-check-string))))))
 936        (when notifications
 937          (labels ((unread-p (notification)
 938                     (if last-check
 939                         (local-time:timestamp>
 940                          (local-time:parse-timestring (cdr (assoc :created-at notification)))
 941                          last-check)
 942                         ;; User has never checked notifications before -- all are unread
 943                         t)))
 944            (if full
 945                (remove-if-not #'unread-p notifications)
 946                (unread-p (first notifications))))))))
 947   (backend-lw2-modernized
 948    (declare (ignore user-id auth-token full since))
 949    (let ((*notifications-base-terms* (remove :null *notifications-base-terms* :key #'cdr)))
 950      (call-next-method))))
 951
 952 (define-cache-database 'backend-lw2-legacy "comment-reply-by-user")
 953
 954 (define-backend-function mark-comment-replied (reply)
 955   (backend-lw2-legacy
 956    (alexandria:when-let* ((parent-comment-id (cdr (assoc :parent-comment-id reply)))
 957                           (reply-id (cdr (assoc :--id reply)))
 958                           (user-id (cdr (assoc :user-id reply))))
 959      (cache-put "comment-reply-by-user" (concatenate 'string parent-comment-id " " user-id) reply-id))))
 960
 961 (define-backend-function check-comment-replied (comment-id user-id)
 962   (backend-lw2-legacy
 963    (cache-get "comment-reply-by-user" (concatenate 'string comment-id " " user-id))))
 964
 965 (define-backend-function get-user-page-items (user-id request-type &key (offset 0) (limit 21) (sort-type :date) drafts
 966                                                       (revalidate *revalidate-default*) (force-revalidate *force-revalidate-default*) auth-token)
 967   (backend-lw2-legacy
 968    (multiple-value-bind (real-offset real-limit) (if (eq request-type :both)
 969                                                      (values 0 (+ offset limit))
 970                                                      (values offset limit))
 971      (let* ((cache-database (when (and (eq request-type :both)
 972                                        (or (not offset) (= offset 0))
 973                                        (= limit 21)
 974                                        (eq sort-type :date)
 975                                        (not drafts)
 976                                        (not auth-token))
 977                               "user-page-items"))
 978             (return-type (if cache-database :string nil))
 979             (fn (lambda ()
 980                   (labels ((posts-query-string ()
 981                              (let* ((base-terms
 982                                      (cond
 983                                        (drafts (alist :view "drafts"))
 984                                        ((eq sort-type :score) (alist :view "top"))
 985                                        ((eq sort-type :date-reverse) (alist :view "old"))
 986                                        (t (alist :view "userPosts"))))
 987                                     (terms (alist* :offset real-offset :limit real-limit :user-id user-id base-terms)))
 988                                (declare (dynamic-extent base-terms terms))
 989                                (lw2-query-string* :post :list terms)))
 990                            (comments-query-string ()
 991                              (let* ((view (ecase sort-type
 992                                                     (:score "postCommentsTop")
 993                                                     (:date "allRecentComments")
 994                                                     (:date-reverse "postCommentsOld")))
 995                                     (terms (alist :offset real-offset
 996                                                   :limit real-limit
 997                                                   :user-id user-id
 998                                                   :view view)))
 999                                (declare (dynamic-extent view terms))
1000                                (lw2-query-string* :comment :list terms
1001                                                   :context :index))))
1002                     (declare (dynamic-extent #'posts-query-string #'comments-query-string))
1003                     (case request-type
1004                       (:both (let ((result (multiple-value-call #'concatenate 'list
1005                                                                 (lw2-graphql-query-multi (list (posts-query-string) (comments-query-string))))))
1006                                (ecase return-type
1007                                  (:string (json:encode-json-to-string result))
1008                                  ((nil) result))))
1009                       (:posts (lw2-graphql-query (format nil "{~A}" (posts-query-string)) :auth-token auth-token :return-type return-type))
1010                       (:comments (lw2-graphql-query (format nil "{~A}" (comments-query-string)) :auth-token auth-token :return-type return-type)))))))
1011        (if cache-database
1012            (lw2-graphql-query-timeout-cached fn cache-database user-id :decoder 'deserialize-query-result :revalidate revalidate :force-revalidate force-revalidate)
1013            (funcall fn))))))
1014
1015 (define-backend-function get-conversation-messages (conversation-id auth-token)
1016   (backend-lw2-legacy
1017    (lw2-graphql-query-multi
1018     (list
1019      (lw2-query-string* :conversation :single (alist :document-id conversation-id) :fields '(:title (:participants :display-name :slug)))
1020      (lw2-query-string* :message :list (alist :view "messagesConversation" :conversation-id conversation-id) :fields *messages-index-fields*))
1021     :auth-token auth-token)))
1022
1023 (define-backend-function lw2-search-query (query &key (indexes '("test_tags" "test_posts" "test_comments")))
1024   (backend-algolia-search
1025    (call-with-http-response
1026     (lambda (req-stream)
1027       (values-list (loop for r in (cdr (assoc :results (json:decode-json req-stream)))
1028                       collect (cdr (assoc :hits r)))))
1029     (algolia-search-uri *current-backend*)
1030     :method :post
1031     :headers '(("Origin" . "https://www.greaterwrong.com")
1032                ("Referer" . "https://www.greaterwrong.com/")
1033                ("Content-Type" . "application/json"))
1034     :content (json:encode-json-alist-to-string
1035               (alist "requests" (loop for index in indexes
1036                                    collect (alist "indexName" index
1037                                                   "params" (format nil "query=~A&hitsPerPage=20&page=0"
1038                                                                    (url-rewrite:url-encode query))))))
1039     :want-stream t)))
1040
1041 (define-backend-function get-username-wrapper (user-id fn)
1042   (backend-base
1043    (funcall fn user-id))
1044   (backend-lw2-modernized
1045    (if (user-deleted user-id)
1046        "[deleted]"
1047        (funcall fn user-id))))
1048
1049 (define-cache-database 'backend-lw2-legacy "comment-markdown-source" "post-markdown-source")
1050
1051 (defun markdown-source-db-name (target-type)
1052   (ecase target-type (:comment "comment-markdown-source") (:post "post-markdown-source")))
1053
1054 (define-backend-function markdown-source (target-type id version)
1055   (backend-lw2-modernized
1056    (let ((db-name (markdown-source-db-name target-type))
1057          (version (base64:usb8-array-to-base64-string (hash-string version))))
1058      (or
1059       (if-let ((cache-data (cache-get db-name id :value-type :lisp)))
1060               (alist-bind ((cached-version simple-string :version)
1061                            (markdown simple-string))
1062                           cache-data
1063                           (when (string= version cached-version)
1064                             markdown)))
1065       (trivia:ematch (lw2-graphql-query (lw2-query-string target-type :single
1066                                                           (alist :document-id id)
1067                                                           :fields '(:html-body (:contents :markdown)))
1068                                         :auth-token *current-auth-token*)
1069                      ((trivia:alist (:html-body . html-body)
1070                                     (:contents . (assoc :markdown markdown)))
1071                       (cache-put db-name id (alist :version (base64:usb8-array-to-base64-string (hash-string html-body)) :markdown markdown) :value-type :lisp)
1072                       markdown))))))
1073
1074 (define-backend-function (setf markdown-source) (markdown target-type id version)
1075   (backend-lw2-modernized
1076    (let ((version (base64:usb8-array-to-base64-string (hash-string version))))
1077      (cache-put (markdown-source-db-name target-type)
1078                 id
1079                 (alist :version version :markdown markdown)
1080                 :value-type :lisp))))
1081
1082 (defun get-elicit-question-title (question-id)
1083   (cdr
1084    (lw2-graphql-query (graphql-query-string "ElicitBlockData" (alist :question-id question-id) '(:title)))))
1085
1086 (defun make-rate-limiter (delay)
1087   (let ((rl-hash (make-hash-table :test 'equal :synchronized t)))
1088     (lambda (datum fn)
1089       (let ((unix-time (get-unix-time)))
1090         (if (sb-ext:with-locked-hash-table (rl-hash)
1091               (maphash (lambda (k v)
1092                          (if (> (- unix-time v) delay)
1093                              (remhash k rl-hash)))
1094                        rl-hash)
1095               (not (gethash datum rl-hash)))
1096             (progn
1097               (setf (gethash datum rl-hash) unix-time)
1098               (funcall fn))
1099             (error "Request aborted due to rate limit."))))))
1100
1101 (defmacro with-rate-limit (&body outer-body)
1102     `(let ((rate-limiter (make-rate-limiter 30)))
1103        (macrolet ((rate-limit ((key) &body inner-body)
1104                     `(funcall rate-limiter ,key (lambda () ,@inner-body))))
1105          ,@outer-body)))
1106
1107 (with-rate-limit
1108   (simple-cacheable ("post-title" 'backend-lw2-legacy "postid-to-title" post-id)
1109     (rate-limit (post-id) (cdr (first (lw2-graphql-query (lw2-query-string :post :single (alist :document-id post-id) :fields '(:title))))))))
1110
1111 (with-rate-limit
1112   (simple-cacheable ("post-slug" 'backend-lw2-legacy "postid-to-slug" post-id)
1113     (rate-limit (post-id) (cdr (first (lw2-graphql-query (lw2-query-string :post :single (alist :document-id post-id) :fields '(:slug))))))))
1114
1115 (with-rate-limit
1116   (simple-cacheable ("slug-postid" 'backend-lw2-legacy "slug-to-postid" slug)
1117     (rate-limit (slug) (cdr (first (lw2-graphql-query (lw2-query-string :post :single (alist :slug slug) :fields '(:--id))))))))
1118
1119 (with-rate-limit
1120   (simple-cacheable ("username" 'backend-lw2-legacy "userid-to-displayname" user-id :get-wrapper #'get-username-wrapper)
1121     (rate-limit (user-id) (cdr (first (lw2-graphql-query (lw2-query-string :user :single (alist :document-id user-id) :fields '(:display-name))))))))
1122
1123 (with-rate-limit
1124   (simple-cacheable ("user-slug" 'backend-lw2-legacy "userid-to-slug" user-id)
1125     (rate-limit (user-id) (cdr (first (lw2-graphql-query (lw2-query-string :user :single (alist :document-id user-id) :fields '(:slug))))))))
1126
1127 (with-rate-limit
1128   (simple-cacheable ("user-full-name" 'backend-lw2-legacy "userid-to-full-name" user-id)
1129     (rate-limit (user-id) (or (cdr (first (lw2-graphql-query (lw2-query-string :user :single (alist :document-id user-id) :fields '(:full-name)))))
1130                               ""))))
1131
1132 (with-rate-limit
1133   (simple-cacheable ("slug-userid" 'backend-lw2-legacy "slug-to-userid" slug)
1134     (rate-limit (slug) (cdr (first (lw2-graphql-query (lw2-query-string :user :single (alist :slug slug) :fields '(:--id))))))))
1135
1136 (with-rate-limit
1137   (simple-cacheable ("slug-tagid" 'backend-lw2-tags "slug-to-tagid" slug :catch-errors nil)
1138     (rate-limit (slug) (cdr (first (first (lw2-graphql-query (lw2-query-string :tag :list (alist :view "tagBySlug" :slug slug) :fields '(:--id)))))))))
1139
1140 (defun preload-username-cache ()
1141   (declare (optimize space (compilation-speed 2) (speed 0)))
1142   (let ((user-list (lw2-graphql-query (lw2-query-string :user :list '() :fields '(:--id :slug :display-name)))))
1143     (with-cache-transaction
1144         (loop for user in user-list
1145            do (alist-bind ((user-id (or simple-string null) :--id)
1146                            (slug (or simple-string null))
1147                            (display-name (or simple-string null)))
1148                           user
1149                 (when user-id
1150                   (when display-name
1151                     (cache-username user-id display-name))
1152                   (when slug
1153                     (cache-user-slug user-id slug)
1154                     (cache-slug-userid slug user-id))))))))