src/add-ons/kernel/file_cache/rule_based_prefetcher.cpp

   1 /*
   2  * Copyright 2005, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6 /** This module applies rules that were learned by another component by
   7  *      evaluating the cache log files.
   8  *
   9  *      Note: this module is using private kernel API and is definitely not
  10  *              meant to be an example on how to write modules.
  11  */
  12
  13
  14 #include <KernelExport.h>
  15 #include <Node.h>
  16
  17 #include <util/kernel_cpp.h>
  18 #include <util/AutoLock.h>
  19 #include <thread.h>
  20 #include <team.h>
  21 #include <file_cache.h>
  22 #include <generic_syscall.h>
  23 #include <syscalls.h>
  24
  25 #include <unistd.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30 #include <ctype.h>
  31
  32
  33 #define TRACE_CACHE_MODULE
  34 #ifdef TRACE_CACHE_MODULE
  35 #       define TRACE(x) dprintf x
  36 #else
  37 #       define TRACE(x) ;
  38 #endif
  39
  40
  41 extern dev_t gBootDevice;
  42
  43
  44 enum match_type {
  45         NO_MATCH,
  46         CONTINUE_MATCHING,
  47         MATCH,
  48 };
  49
  50 enum rule_type {
  51         LAUNCH_TYPE             = 0x1,
  52         OPEN_FILE_TYPE  = 0x2,
  53         ARGUMENTS_TYPE  = 0x4,
  54         ALL_TYPES               = 0xff,
  55 };
  56
  57 struct head {
  58         head();
  59
  60         struct list_link        link;
  61         mount_id                        device;
  62         vnode_id                        parent;
  63         vnode_id                        node;
  64         char                            name[B_FILE_NAME_LENGTH];
  65         int32                           confidence;
  66         bigtime_t                       timestamp;
  67         int32                           used_count;
  68 };
  69
  70 struct body {
  71         struct list_link        link;
  72 };
  73
  74 class Rule {
  75         public:
  76                 Rule(rule_type type);
  77                 ~Rule();
  78
  79                 status_t InitCheck();
  80                 rule_type Type() const { return fType; }
  81
  82                 void AddHead(struct head *head);
  83                 void AddBody(struct body *body);
  84
  85                 struct head *FindHead(mount_id device, vnode_id node);
  86                 match_type Match(int32 state, mount_id device, vnode_id parent,
  87                         const char *name);
  88                 void Apply();
  89
  90                 void KnownFileOpened() { fKnownFileOpened++; }
  91                 void UnknownFileOpened() { fUnknownFileOpened++; }
  92
  93                 void Dump();
  94
  95                 Rule *&Next() { return fNext; }
  96
  97                 static uint32 NextOffset() { return offsetof(Rule, fNext); }
  98                 static status_t LoadRules();
  99
 100         private:
 101                 Rule            *fNext;
 102                 rule_type       fType;
 103                 struct list     fHeads;
 104                 struct list     fBodies;
 105                 int32           fHeadCount;
 106                 int32           fBodyCount;
 107                 int32           fConfidence;
 108                 int32           fAppliedCount;
 109                 int32           fKnownFileOpened;
 110                 int32           fUnknownFileOpened;
 111 };
 112
 113 struct rule_state {
 114         list_link       link;
 115         Rule            *rule;
 116         int32           state;
 117 };
 118
 119 struct rules {
 120         rules           *next;
 121         char            name[B_FILE_NAME_LENGTH];
 122         Rule            *first;
 123 };
 124
 125 struct team_rules {
 126         ~team_rules();
 127
 128         team_rules      *next;
 129         team_id         team;
 130         struct list     states;
 131         struct list     applied;
 132         bigtime_t       timestamp;
 133 };
 134
 135 class RuleMatcher {
 136         public:
 137                 RuleMatcher(team_id team, const char *name = NULL);
 138                 ~RuleMatcher();
 139
 140                 void GotFile(mount_id device, vnode_id node);
 141                 void GotArguments(int32 argCount, char * const *args);
 142
 143         private:
 144                 void _CollectRules(const char *name);
 145                 void _MatchFile(mount_id device, vnode_id parent, const char *name);
 146                 void _MatchArguments(int32 argCount, char * const *args);
 147
 148                 team_rules      *fRules;
 149 };
 150
 151
 152 struct RuleHash {
 153                 typedef char*           KeyType;
 154                 typedef rules           ValueType;
 155
 156                 size_t HashKey(KeyType key) const
 157                 {
 158                         return hash_hash_string(key);
 159                 }
 160
 161                 size_t Hash(ValueType* value) const
 162                 {
 163                         return HashKey(value->name);
 164                 }
 165
 166                 bool Compare(KeyType key, ValueType* rules) const
 167                 {
 168                         return strcmp(rules->name, key) == 0;
 169                 }
 170
 171                 ValueType*& GetLink(ValueType* value) const
 172                 {
 173                         return value->fNext;
 174                 }
 175 };
 176
 177
 178 struct TeamHash {
 179                 typedef team_id         KeyType;
 180                 typedef team_rules      ValueType;
 181
 182                 size_t HashKey(KeyType key) const
 183                 {
 184                         return key;
 185                 }
 186
 187                 size_t Hash(ValueType* value) const
 188                 {
 189                         return value->team;
 190                 }
 191
 192                 bool Compare(KeyType key, ValueType* value) const
 193                 {
 194                         return value->team == key;
 195                 }
 196
 197                 ValueType*& GetLink(ValueType* value) const
 198                 {
 199                         return value->fNext;
 200                 }
 201 };
 202
 203
 204 typedef BOpenHashTable<RuleHash> RuleTable;
 205 typedef BOpenHashTable<TeamHash> TeamTable;
 206
 207 static RuleTable *sRulesHash;
 208 static TeamTable *sTeamHash;
 209 static recursive_lock sLock;
 210 int32 sMinConfidence = 5000;
 211
 212
 213 static void
 214 team_gone(team_id team, void *_rules)
 215 {
 216         team_rules *rules = (team_rules *)_rules;
 217
 218         recursive_lock_lock(&sLock);
 219         sTeamHash->Remove(rules);
 220         recursive_lock_unlock(&sLock);
 221
 222         delete rules;
 223 }
 224
 225
 226 team_rules::~team_rules()
 227 {
 228         // free rule states
 229
 230         rule_state *state;
 231         while ((state = (rule_state *)list_remove_head_item(&states)) != NULL) {
 232                 delete state;
 233         }
 234         while ((state = (rule_state *)list_remove_head_item(&applied)) != NULL) {
 235                 delete state;
 236         }
 237
 238         stop_watching_team(team, team_gone, this);
 239 }
 240
 241
 242 //      #pragma mark -
 243
 244
 245 head::head()
 246 {
 247         device = -1;
 248         parent = -1;
 249         node = -1;
 250         name[0] = '\0';
 251         confidence = -1;
 252         timestamp = 0;
 253         used_count = 0;
 254 }
 255
 256
 257 static inline rules *
 258 find_rules(const char *name)
 259 {
 260         return sRulesHash->Lookup(name);
 261 }
 262
 263
 264 /**     Finds the rule matching to the criteria (name and type).
 265  *      If there is no matching rule yet, it will create one.
 266  *      It will only return NULL in out of memory conditions.
 267  */
 268
 269 static Rule *
 270 get_rule(const char *name, rule_type type)
 271 {
 272         struct rules *rules = find_rules(name);
 273         if (rules == NULL) {
 274                 // add new rules
 275                 rules = new ::rules;
 276                 if (rules == NULL)
 277                         return NULL;
 278
 279                 strlcpy(rules->name, name, B_FILE_NAME_LENGTH);
 280                 rules->first = NULL;
 281                 sRulesHash->Insert(rules);
 282         }
 283
 284         // search for matching rule type
 285
 286         Rule *rule = rules->first;
 287         while (rule && rule->Type() != type) {
 288                 rule = rule->Next();
 289         }
 290
 291         if (rule == NULL) {
 292                 TRACE(("create new rule for \"%s\", type %d\n", name, type));
 293                 // there is no rule yet, create one
 294                 rule = new Rule(type);
 295                 if (rule == NULL)
 296                         return NULL;
 297
 298                 rule->Next() = rules->first;
 299                 rules->first = rule;
 300         }
 301
 302         return rule;
 303 }
 304
 305
 306 static void
 307 eat_spaces(char *&line)
 308 {
 309         // eat starting white space
 310         while (isspace(line[0]))
 311                 line++;
 312 }
 313
 314
 315 static bool
 316 parse_ref(const char *string, mount_id &device, vnode_id &node, char **_end = NULL)
 317 {
 318         // parse node ref
 319         char *end;
 320         device = strtol(string, &end, 0);
 321         if (end == NULL || device == 0 || end[0] != ':')
 322                 return false;
 323
 324         node = strtoull(end + 1, &end, 0);
 325         if (end == NULL || end[0] != ':')
 326                 return false;
 327
 328         if (_end)
 329                 *_end = end + 1;
 330         return true;
 331 }
 332
 333
 334 static void
 335 ignore_line(char *&line)
 336 {
 337         while (line[0] && line[0] != '\n')
 338                 line++;
 339 }
 340
 341
 342 static const char *
 343 get_name(char *&line)
 344 {
 345         if (line[0] != '"')
 346                 return NULL;
 347
 348         const char *name = ++line;
 349
 350         while (line[0] && line[0] != '"') {
 351                 if (line[0] == '\\')
 352                         line++;
 353                 line++;
 354         }
 355
 356         line[0] = '\0';
 357         line++;
 358
 359         return name;
 360 }
 361
 362
 363 static status_t
 364 load_rules()
 365 {
 366         int fd = open("/etc/cache_rules", O_RDONLY);
 367         if (fd < B_OK)
 368                 return fd;
 369
 370         struct stat stat;
 371         if (fstat(fd, &stat) != 0) {
 372                 close(fd);
 373                 return errno;
 374         }
 375
 376         if (stat.st_size > 32767) {
 377                 // for safety reasons
 378                 // ToDo: make a bit larger later
 379                 close(fd);
 380                 return B_BAD_DATA;
 381         }
 382
 383         char *buffer = (char *)malloc(stat.st_size + 1);
 384         if (buffer == NULL) {
 385                 close(fd);
 386                 return B_NO_MEMORY;
 387         }
 388
 389         if (read(fd, buffer, stat.st_size) < stat.st_size) {
 390                 free(buffer);
 391                 close(fd);
 392                 return B_ERROR;
 393         }
 394
 395         buffer[stat.st_size] = '\0';
 396
 397         char *line = buffer;
 398         while (line[0]) {
 399                 switch (line[0]) {
 400                         case 'c':
 401                         {
 402                                 mount_id device;
 403                                 vnode_id node;
 404
 405                                 // direct "command opens file" rule
 406                                 line += 2;
 407                                 if (parse_ref(line, device, node, &line)) {
 408                                         const char *fileName = get_name(line);
 409                                         if (fileName != NULL) {
 410                                                 eat_spaces(line);
 411                                                 const char *name = get_name(line);
 412                                                 if (name != NULL) {
 413                                                         eat_spaces(line);
 414                                                         int32 confidence = strtoul(line, &line, 10);
 415                                                         TRACE(("c %ld:%Ld:%s %s %ld\n", device, node, fileName, name, confidence));
 416
 417                                                         struct head *head = new ::head;
 418                                                         head->device = device;
 419                                                         head->parent = node;
 420                                                         strlcpy(head->name, fileName, B_FILE_NAME_LENGTH);
 421                                                         head->confidence = confidence;
 422
 423                                                         Rule *rule = get_rule(name, LAUNCH_TYPE);
 424                                                         if (rule != NULL)
 425                                                                 rule->AddHead(head);
 426                                                         break;
 427                                                 }
 428                                         }
 429                                 }
 430                                 ignore_line(line);
 431                                 break;
 432                         }
 433                         default:
 434                                 // unknown rule - ignore line
 435                                 ignore_line(line);
 436                                 break;
 437                 }
 438                 line++;
 439         }
 440
 441         free(buffer);
 442         close(fd);
 443         return B_OK;
 444 }
 445
 446
 447 //      #pragma mark -
 448
 449
 450 Rule::Rule(rule_type type)
 451         :
 452         fType(type),
 453         fHeadCount(0),
 454         fBodyCount(0),
 455         fAppliedCount(0),
 456         fKnownFileOpened(0),
 457         fUnknownFileOpened(0)
 458 {
 459         list_init(&fHeads);
 460         list_init(&fBodies);
 461 }
 462
 463
 464 Rule::~Rule()
 465 {
 466         struct head *head;
 467         while ((head = (struct head *)list_remove_head_item(&fHeads)) != NULL) {
 468                 delete head;
 469         }
 470
 471         struct body *body;
 472         while ((body = (struct body *)list_remove_head_item(&fBodies)) != NULL) {
 473                 delete body;
 474         }
 475 }
 476
 477
 478 void
 479 Rule::AddHead(struct head *head)
 480 {
 481         list_add_item(&fHeads, head);
 482         fHeadCount++;
 483 }
 484
 485
 486 void
 487 Rule::AddBody(struct body *body)
 488 {
 489         list_add_item(&fBodies, body);
 490         fBodyCount++;
 491 }
 492
 493
 494 void
 495 Rule::Apply()
 496 {
 497         TRACE(("Apply rule %p", this));
 498
 499         struct head *head = NULL;
 500         while ((head = (struct head *)list_get_next_item(&fHeads, head)) != NULL) {
 501                 if (head->confidence < sMinConfidence)
 502                         continue;
 503
 504                 // prefetch node
 505                 void *vnode;
 506                 if (vfs_entry_ref_to_vnode(head->device, head->parent, head->name, &vnode) == B_OK) {
 507                         vfs_vnode_to_node_ref(vnode, &head->device, &head->node);
 508
 509                         TRACE(("prefetch: %ld:%Ld:%s\n", head->device, head->parent, head->name));
 510                         cache_prefetch(head->device, head->node, 0, ~0UL);
 511
 512                         // ToDo: put head into a hash so that some statistics can be backpropagated quickly
 513                 } else {
 514                         // node doesn't exist anymore
 515                         head->confidence = -1;
 516                 }
 517         }
 518
 519         fAppliedCount++;
 520 }
 521
 522
 523 struct head *
 524 Rule::FindHead(mount_id device, vnode_id node)
 525 {
 526         // ToDo: use a hash for this!
 527
 528         struct head *head = NULL;
 529         while ((head = (struct head *)list_get_next_item(&fHeads, head)) != NULL) {
 530                 if (head->node == node && head->device == device)
 531                         return head;
 532         }
 533
 534         return NULL;
 535 }
 536
 537
 538 void
 539 Rule::Dump()
 540 {
 541         dprintf("  applied: %ld, known: %ld, unknown: %ld\n",
 542                 fAppliedCount, fKnownFileOpened, fUnknownFileOpened);
 543
 544         struct head *head = NULL;
 545         while ((head = (struct head *)list_get_next_item(&fHeads, head)) != NULL) {
 546                 dprintf("  %ld:%Ld:\"%s\", ", head->device, head->parent, head->name);
 547                 if (head->confidence < sMinConfidence)
 548                         dprintf("-\n");
 549                 else
 550                         dprintf("%ld (%ld), %Ld us\n", head->used_count,
 551                                 head->used_count - fAppliedCount, head->timestamp);
 552         }
 553 }
 554
 555
 556 //      #pragma mark -
 557
 558
 559 RuleMatcher::RuleMatcher(team_id team, const char *name)
 560         :
 561         fRules(NULL)
 562 {
 563         recursive_lock_lock(&sLock);
 564
 565         if (name == NULL)
 566                 return;
 567
 568         fRules = sTeamHash->Lookup(team);
 569         if (fRules != NULL)
 570                 return;
 571
 572         fRules = new team_rules;
 573         if (fRules == NULL)
 574                 return;
 575
 576         fRules->team = team;
 577         list_init(&fRules->states);
 578         list_init(&fRules->applied);
 579
 580 dprintf("new rules for \"%s\"\n", name);
 581         _CollectRules(name);
 582
 583         sTeamHash->Insert(fRules);
 584         start_watching_team(team, team_gone, fRules);
 585
 586         fRules->timestamp = system_time();
 587 }
 588
 589
 590 RuleMatcher::~RuleMatcher()
 591 {
 592         recursive_lock_unlock(&sLock);
 593 }
 594
 595
 596 void
 597 RuleMatcher::_CollectRules(const char *name)
 598 {
 599         struct rules *rules = sRulesHash->Lookup(name);
 600         if (rules == NULL) {
 601                 // there are no rules for this command
 602                 return;
 603         }
 604
 605         // allocate states for all rules found
 606
 607         for (Rule *rule = rules->first; rule != NULL; rule = rule->Next()) {
 608                 rule_state *state = new rule_state;
 609                 if (state == NULL)
 610                         continue;
 611
 612                 TRACE(("found rule %p for \"%s\"\n", rule, rules->name));
 613                 state->rule = rule;
 614                 state->state = 0;
 615
 616                 if (rule->Type() == LAUNCH_TYPE) {
 617                         // we can already prefetch the simplest of all rules here
 618                         // (it's fulfilled as soon as the command is launched)
 619                         rule->Apply();
 620                         list_add_item(&fRules->applied, state);
 621                 } else
 622                         list_add_item(&fRules->states, state);
 623         }
 624 }
 625
 626
 627 void
 628 RuleMatcher::GotFile(mount_id device, vnode_id node)
 629 {
 630         if (fRules == NULL)
 631                 return;
 632
 633         // try to match the file with all open rules
 634
 635         rule_state *state = NULL;
 636         while ((state = (rule_state *)list_get_next_item(&fRules->states, state)) != NULL) {
 637                 if ((state->rule->Type() & OPEN_FILE_TYPE) == 0)
 638                         continue;
 639
 640                 // ToDo
 641         }
 642
 643         bigtime_t diff = system_time() - fRules->timestamp;
 644
 645         // propagate the usage of this file back to the applied rules
 646
 647         while ((state = (rule_state *)list_get_next_item(&fRules->applied, state)) != NULL) {
 648                 struct head *head = state->rule->FindHead(device, node);
 649                 if (head != NULL) {
 650                         // grow confidence
 651                         state->rule->KnownFileOpened();
 652                         head->used_count++;
 653                         if (head->used_count > 1)
 654                                 head->timestamp = (head->timestamp * (head->used_count - 1) + diff) / head->used_count;
 655                 } else
 656                         state->rule->UnknownFileOpened();
 657         }
 658 }
 659
 660
 661 void
 662 RuleMatcher::GotArguments(int32 argCount, char * const *args)
 663 {
 664         if (fRules == NULL)
 665                 return;
 666
 667         // try to match the arguments with all open rules
 668
 669         rule_state *state = NULL;
 670         while ((state = (rule_state *)list_get_next_item(&fRules->states, state)) != NULL) {
 671                 if ((state->rule->Type() & ARGUMENTS_TYPE) == 0)
 672                         continue;
 673
 674                 // ToDo
 675         }
 676 }
 677
 678
 679 //      #pragma mark -
 680
 681
 682 static void
 683 node_opened(void *vnode, int32 fdType, mount_id device, vnode_id parent,
 684         vnode_id node, const char *name, off_t size)
 685 {
 686         if (device < gBootDevice) {
 687                 // we ignore any access to rootfs, pipefs, and devfs
 688                 // ToDo: if we can ever move the boot device on the fly, this will break
 689                 return;
 690         }
 691
 692         // ToDo: this is only needed if there is no rule for this team yet - ideally,
 693         //      it would be handled by the log module, so that the vnode ID is sufficient
 694         //      to recognize a rule
 695         char buffer[B_FILE_NAME_LENGTH];
 696         if (name == NULL
 697                 && vfs_get_vnode_name(vnode, buffer, sizeof(buffer)) == B_OK)
 698                 name = buffer;
 699
 700         //dprintf("opened: %ld:%Ld:%Ld:%s (%s)\n", device, parent, node, name, thread_get_current_thread()->name);
 701         RuleMatcher matcher(team_get_current_team_id(), name);
 702         matcher.GotFile(device, node);
 703 }
 704
 705
 706 static void
 707 node_launched(size_t argCount, char * const *args)
 708 {
 709         //dprintf("launched: %s (%s)\n", args[0], thread_get_current_thread()->name);
 710         RuleMatcher matcher(team_get_current_team_id());
 711         matcher.GotArguments(argCount, args);
 712 }
 713
 714
 715 static void
 716 uninit()
 717 {
 718         recursive_lock_lock(&sLock);
 719
 720         // free all sessions from the hashes
 721
 722         team_rules *teamRules = sTeamHash->Clear(true);
 723         while ((teamRules != NULL) {
 724                 team_rules *next = teamRules->next;
 725                 delete teamRules;
 726                 teamRules = next;
 727         }
 728
 729         struct rules *rules = sRulesHash->Clear(true);
 730         while ((rules != NULL) {
 731                 Rule *rule = rules->first;
 732                 while (rule) {
 733                         Rule *next = rule->Next();
 734
 735                         dprintf("Rule %p \"%s\"\n", rule, rules->name);
 736                         rule->Dump();
 737
 738                         delete rule;
 739                         rule = next;
 740                 }
 741
 742                 struct rules *next = rules->next;
 743                 delete rules;
 744                 rules = next;
 745         }
 746
 747         delete sTeamHash;
 748         delete sRulesHash;
 749         recursive_lock_destroy(&sLock);
 750 }
 751
 752
 753 static status_t
 754 init()
 755 {
 756         sTeamHash = new(std::nothrow) TeamTable();
 757         if (sTeamHash == NULL || sTeamHash->Init(64) != B_OK)
 758                 return B_NO_MEMORY;
 759
 760         status_t status;
 761
 762         sRulesHash = new(std::nothrow) RuleTable();
 763         if (sRulesHash == NULL || sRulesHash->Init(64) != B_OK) {
 764                 delete sTeamHash;
 765                 return B_NO_MEMORY;
 766         }
 767
 768         recursive_lock_init(&sLock, "rule based prefetcher");
 769
 770         load_rules();
 771         return B_OK;
 772 }
 773
 774
 775 static status_t
 776 std_ops(int32 op, ...)
 777 {
 778         switch (op) {
 779                 case B_MODULE_INIT:
 780                         return init();
 781
 782                 case B_MODULE_UNINIT:
 783                         uninit();
 784                         return B_OK;
 785
 786                 default:
 787                         return B_ERROR;
 788         }
 789 }
 790
 791
 792 static struct cache_module_info sRuleBasedPrefetcherModule = {
 793         {
 794                 CACHE_MODULES_NAME "/rule_based_prefetcher/v1",
 795                 0,
 796                 std_ops,
 797         },
 798         node_opened,
 799         NULL,
 800         node_launched,
 801 };
 802
 803
 804 module_info *modules[] = {
 805         (module_info *)&sRuleBasedPrefetcherModule,
 806         NULL
 807 };