src/Store.h

   1 /*
   2  *
   3  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   4  * ----------------------------------------------------------
   5  *
   6  *  Squid is the result of efforts by numerous individuals from
   7  *  the Internet community; see the CONTRIBUTORS file for full
   8  *  details.   Many organizations have provided support for Squid's
   9  *  development; see the SPONSORS file for full details.  Squid is
  10  *  Copyrighted (C) 2001 by the Regents of the University of
  11  *  California; see the COPYRIGHT file for full details.  Squid
  12  *  incorporates software developed and/or copyrighted by other
  13  *  sources; see the CREDITS file for full details.
  14  *
  15  *  This program is free software; you can redistribute it and/or modify
  16  *  it under the terms of the GNU General Public License as published by
  17  *  the Free Software Foundation; either version 2 of the License, or
  18  *  (at your option) any later version.
  19  *
  20  *  This program is distributed in the hope that it will be useful,
  21  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  *  GNU General Public License for more details.
  24  *
  25  *  You should have received a copy of the GNU General Public License
  26  *  along with this program; if not, write to the Free Software
  27  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  28  *
  29  */
  30 #ifndef SQUID_STORE_H
  31 #define SQUID_STORE_H
  32
  33 /**
  34  \defgroup StoreAPI  Store API
  35  \ingroup FileSystems
  36  */
  37
  38 #include "base/RefCount.h"
  39 #include "comm/forward.h"
  40 #include "CommRead.h"
  41 #include "hash.h"
  42 #include "http/forward.h"
  43 #include "http/RequestMethod.h"
  44 #include "HttpReply.h"
  45 #include "MemObject.h"
  46 #include "Range.h"
  47 #include "RemovalPolicy.h"
  48 #include "StoreIOBuffer.h"
  49 #include "StoreStats.h"
  50
  51 #if USE_SQUID_ESI
  52 #include "esi/Element.h"
  53 #endif
  54
  55 #include <ostream>
  56
  57 class AsyncCall;
  58 class HttpRequest;
  59 class Packer;
  60 class RequestFlags;
  61 class StoreClient;
  62 class StoreSearch;
  63 class SwapDir;
  64
  65 extern StoreIoStats store_io_stats;
  66
  67 /// maximum number of entries per cache_dir
  68 enum { SwapFilenMax = 0xFFFFFF }; // keep in sync with StoreEntry::swap_filen
  69
  70 /**
  71  \ingroup StoreAPI
  72  */
  73 class StoreEntry : public hash_link
  74 {
  75
  76 public:
  77     static DeferredRead::DeferrableRead DeferReader;
  78     bool checkDeferRead(int fd) const;
  79
  80     virtual const char *getMD5Text() const;
  81     StoreEntry();
  82     virtual ~StoreEntry();
  83
  84     virtual HttpReply const *getReply() const;
  85     virtual void write (StoreIOBuffer);
  86
  87     /** Check if the Store entry is emtpty
  88      * \retval true   Store contains 0 bytes of data.
  89      * \retval false  Store contains 1 or more bytes of data.
  90      * \retval false  Store contains negative content !!!!!!
  91      */
  92     virtual bool isEmpty() const {
  93         assert (mem_obj);
  94         return mem_obj->endOffset() == 0;
  95     }
  96     virtual bool isAccepting() const;
  97     virtual size_t bytesWanted(Range<size_t> const aRange, bool ignoreDelayPool = false) const;
  98     virtual void complete();
  99     virtual store_client_t storeClientType() const;
 100     virtual char const *getSerialisedMetaData();
 101     /// Store a prepared error response. MemObject locks the reply object.
 102     void storeErrorResponse(HttpReply *reply);
 103     void replaceHttpReply(HttpReply *, bool andStartWriting = true);
 104     void startWriting(); ///< pack and write reply headers and, maybe, body
 105     /// whether we may start writing to disk (now or in the future)
 106     virtual bool mayStartSwapOut();
 107     virtual void trimMemory(const bool preserveSwappable);
 108
 109     // called when a decision to cache in memory has been made
 110     void memOutDecision(const bool willCacheInRam);
 111     // called when a decision to cache on disk has been made
 112     void swapOutDecision(const MemObject::SwapOut::Decision &decision);
 113
 114     void abort();
 115     void unlink();
 116     void makePublic();
 117     void makePrivate();
 118     void setPublicKey();
 119     void setPrivateKey();
 120     void expireNow();
 121     void releaseRequest();
 122     void negativeCache();
 123     void cacheNegatively();             /** \todo argh, why both? */
 124     void invokeHandlers();
 125     void purgeMem();
 126     void cacheInMemory(); ///< start or continue storing in memory cache
 127     void swapOut();
 128     /// whether we are in the process of writing this entry to disk
 129     bool swappingOut() const { return swap_status == SWAPOUT_WRITING; }
 130     void swapOutFileClose(int how);
 131     const char *url() const;
 132     /// Satisfies cachability requirements shared among disk and RAM caches.
 133     /// Encapsulates common checks of mayStartSwapOut() and memoryCachable().
 134     /// TODO: Rename and make private so only those two methods can call this.
 135     bool checkCachable();
 136     int checkNegativeHit() const;
 137     int locked() const;
 138     int validToSend() const;
 139     bool memoryCachable(); ///< checkCachable() and can be cached in memory
 140
 141     /// if needed, initialize mem_obj member w/o URI-related information
 142     MemObject *makeMemObject();
 143
 144     /// initialize mem_obj member (if needed) and supply URI-related info
 145     void createMemObject(const char *storeId, const char *logUri, const HttpRequestMethod &aMethod);
 146
 147     void dump(int debug_lvl) const;
 148     void hashDelete();
 149     void hashInsert(const cache_key *);
 150     void registerAbort(STABH * cb, void *);
 151     void reset();
 152     void setMemStatus(mem_status_t);
 153     void timestampsSet();
 154     void unregisterAbort();
 155     void destroyMemObject();
 156     int checkTooSmall();
 157
 158     void delayAwareRead(const Comm::ConnectionPointer &conn, char *buf, int len, AsyncCall::Pointer callback);
 159
 160     void setNoDelay (bool const);
 161     bool modifiedSince(HttpRequest * request) const;
 162     /// has ETag matching at least one of the If-Match etags
 163     bool hasIfMatchEtag(const HttpRequest &request) const;
 164     /// has ETag matching at least one of the If-None-Match etags
 165     bool hasIfNoneMatchEtag(const HttpRequest &request) const;
 166     /// whether this entry has an ETag; if yes, puts ETag value into parameter
 167     bool hasEtag(ETag &etag) const;
 168
 169     /** What store does this entry belong too ? */
 170     virtual RefCount<SwapDir> store() const;
 171
 172     MemObject *mem_obj;
 173     RemovalPolicyNode repl;
 174     /* START OF ON-DISK STORE_META_STD TLV field */
 175     time_t timestamp;
 176     time_t lastref;
 177     time_t expires;
 178     time_t lastmod;
 179     uint64_t swap_file_sz;
 180     uint16_t refcount;
 181     uint16_t flags;
 182     /* END OF ON-DISK STORE_META_STD */
 183
 184     /// unique ID inside a cache_dir for swapped out entries; -1 for others
 185     sfileno swap_filen:25; // keep in sync with SwapFilenMax
 186
 187     sdirno swap_dirn:7;
 188
 189     mem_status_t mem_status:3;
 190
 191     ping_status_t ping_status:3;
 192
 193     store_status_t store_status:3;
 194
 195     swap_status_t swap_status:3;
 196
 197 public:
 198     static size_t inUseCount();
 199     static void getPublicByRequestMethod(StoreClient * aClient, HttpRequest * request, const HttpRequestMethod& method);
 200     static void getPublicByRequest(StoreClient * aClient, HttpRequest * request);
 201     static void getPublic(StoreClient * aClient, const char *uri, const HttpRequestMethod& method);
 202
 203     virtual bool isNull() {
 204         return false;
 205     };
 206
 207     void *operator new(size_t byteCount);
 208     void operator delete(void *address);
 209     void setReleaseFlag();
 210 #if USE_SQUID_ESI
 211
 212     ESIElement::Pointer cachedESITree;
 213 #endif
 214     /** append bytes to the buffer */
 215     virtual void append(char const *, int len);
 216     /** disable sending content to the clients */
 217     virtual void buffer();
 218     /** flush any buffered content */
 219     virtual void flush();
 220     virtual int64_t objectLen() const;
 221     virtual int64_t contentLen() const;
 222
 223     /// claim shared ownership of this entry (for use in a given context)
 224     /// matching lock() and unlock() contexts eases leak triage but is optional
 225     void lock(const char *context);
 226
 227     /// disclaim shared ownership; may remove entry from store and delete it
 228     /// returns remaning lock level (zero for unlocked and possibly gone entry)
 229     int unlock(const char *context);
 230
 231     /// returns a local concurrent use counter, for debugging
 232     int locks() const { return static_cast<int>(lock_count); }
 233
 234     /// update last reference timestamp and related Store metadata
 235     void touch();
 236
 237     virtual void release();
 238
 239 #if USE_ADAPTATION
 240     /// call back producer when more buffer space is available
 241     void deferProducer(const AsyncCall::Pointer &producer);
 242     /// calls back producer registered with deferProducer
 243     void kickProducer();
 244 #endif
 245
 246 protected:
 247     void transientsAbandonmentCheck();
 248
 249 private:
 250     static MemAllocator *pool;
 251
 252     unsigned short lock_count;          /* Assume < 65536! */
 253
 254 #if USE_ADAPTATION
 255     /// producer callback registered with deferProducer
 256     AsyncCall::Pointer deferredProducer;
 257 #endif
 258
 259     bool validLength() const;
 260     bool hasOneOfEtags(const String &reqETags, const bool allowWeakMatch) const;
 261 };
 262
 263 std::ostream &operator <<(std::ostream &os, const StoreEntry &e);
 264
 265 /// \ingroup StoreAPI
 266 class NullStoreEntry:public StoreEntry
 267 {
 268
 269 public:
 270     static NullStoreEntry *getInstance();
 271     bool isNull() {
 272         return true;
 273     }
 274
 275     const char *getMD5Text() const;
 276     HttpReply const *getReply() const { return NULL; }
 277     void write (StoreIOBuffer) {}
 278
 279     bool isEmpty () const {return true;}
 280
 281     virtual size_t bytesWanted(Range<size_t> const aRange, bool ignoreDelayPool = false) const { return aRange.end; }
 282
 283     void operator delete(void *address);
 284     void complete() {}
 285
 286 private:
 287     store_client_t storeClientType() const {return STORE_MEM_CLIENT;}
 288
 289     char const *getSerialisedMetaData();
 290     virtual bool mayStartSwapOut() { return false; }
 291
 292     void trimMemory(const bool preserveSwappable) {}
 293
 294     static NullStoreEntry _instance;
 295 };
 296
 297 /// \ingroup StoreAPI
 298 typedef void (*STOREGETCLIENT) (StoreEntry *, void *cbdata);
 299
 300 /**
 301  \ingroup StoreAPI
 302  * Abstract base class that will replace the whole store and swapdir interface.
 303  */
 304 class Store : public RefCountable
 305 {
 306
 307 public:
 308     /** The root store */
 309     static Store &Root() {
 310         if (CurrentRoot == NULL)
 311             fatal("No Store Root has been set");
 312         return *CurrentRoot;
 313     }
 314     static void Root(Store *);
 315     static void Root(RefCount<Store>);
 316     static void Stats(StoreEntry * output);
 317     static void Maintain(void *unused);
 318
 319     virtual ~Store() {}
 320
 321     /** Handle pending callbacks - called by the event loop. */
 322     virtual int callback() = 0;
 323
 324     /** create the resources needed for this store to operate */
 325     virtual void create();
 326
 327     /**
 328      * Notify this store that its disk is full.
 329      \todo XXX move into a protected api call between store files and their stores, rather than a top level api call
 330      */
 331     virtual void diskFull();
 332
 333     /** Retrieve a store entry from the store */
 334     virtual StoreEntry * get(const cache_key *) = 0;
 335
 336     /** \todo imeplement the async version */
 337     virtual void get(String const key , STOREGETCLIENT callback, void *cbdata) = 0;
 338
 339     /* prepare the store for use. The store need not be usable immediately,
 340      * it should respond to readable() and writable() with true as soon
 341      * as it can provide those services
 342      */
 343     virtual void init() = 0;
 344
 345     /**
 346      * The maximum size the store will support in normal use. Inaccuracy is permitted,
 347      * but may throw estimates for memory etc out of whack.
 348      */
 349     virtual uint64_t maxSize() const = 0;
 350
 351     /** The minimum size the store will shrink to via normal housekeeping */
 352     virtual uint64_t minSize() const = 0;
 353
 354     /** current store size */
 355     virtual uint64_t currentSize() const = 0;
 356
 357     /** the total number of objects stored */
 358     virtual uint64_t currentCount() const = 0;
 359
 360     /** the maximum object size that can be stored, -1 if unlimited */
 361     virtual int64_t maxObjectSize() const = 0;
 362
 363     /// collect cache storage-related statistics
 364     virtual void getStats(StoreInfoStats &stats) const = 0;
 365
 366     /**
 367      * Output stats to the provided store entry.
 368      \todo make these calls asynchronous
 369      */
 370     virtual void stat(StoreEntry &) const = 0;
 371
 372     /** Sync the store prior to shutdown */
 373     virtual void sync();
 374
 375     /** remove a Store entry from the store */
 376     virtual void unlink (StoreEntry &);
 377
 378     /* search in the store */
 379     virtual StoreSearch *search(String const url, HttpRequest *) = 0;
 380
 381     /* pulled up from SwapDir for migration.... probably do not belong here */
 382     virtual void reference(StoreEntry &) = 0;   /* Reference this object */
 383
 384     /// Undo reference(), returning false iff idle e should be destroyed
 385     virtual bool dereference(StoreEntry &e, bool wantsLocalMemory) = 0;
 386
 387     virtual void maintain() = 0; /* perform regular maintenance should be private and self registered ... */
 388
 389     // XXX: This method belongs to Store::Root/StoreController, but it is here
 390     // to avoid casting Root() to StoreController until Root() API is fixed.
 391     /// informs stores that this entry will be eventually unlinked
 392     virtual void markForUnlink(StoreEntry &e) {}
 393
 394     // XXX: This method belongs to Store::Root/StoreController, but it is here
 395     // because test cases use non-StoreController derivatives as Root
 396     /// called when the entry is no longer needed by any transaction
 397     virtual void handleIdleEntry(StoreEntry &e) {}
 398
 399     // XXX: This method belongs to Store::Root/StoreController, but it is here
 400     // because test cases use non-StoreController derivatives as Root
 401     /// called to get rid of no longer needed entry data in RAM, if any
 402     virtual void memoryOut(StoreEntry &e, const bool preserveSwappable) {}
 403
 404     // XXX: This method belongs to Store::Root/StoreController, but it is here
 405     // to avoid casting Root() to StoreController until Root() API is fixed.
 406     /// makes the entry available for collapsing future requests
 407     virtual void allowCollapsing(StoreEntry *e, const RequestFlags &reqFlags, const HttpRequestMethod &reqMethod) {}
 408
 409     // XXX: This method belongs to Store::Root/StoreController, but it is here
 410     // to avoid casting Root() to StoreController until Root() API is fixed.
 411     /// marks the entry completed for collapsed requests
 412     virtual void transientsCompleteWriting(StoreEntry &e) {}
 413
 414     // XXX: This method belongs to Store::Root/StoreController, but it is here
 415     // to avoid casting Root() to StoreController until Root() API is fixed.
 416     /// Update local intransit entry after changes made by appending worker.
 417     virtual void syncCollapsed(const sfileno xitIndex) {}
 418
 419     // XXX: This method belongs to Store::Root/StoreController, but it is here
 420     // to avoid casting Root() to StoreController until Root() API is fixed.
 421     /// calls Root().transients->abandon() if transients are tracked
 422     virtual void transientsAbandon(StoreEntry &e) {}
 423
 424     // XXX: This method belongs to Store::Root/StoreController, but it is here
 425     // to avoid casting Root() to StoreController until Root() API is fixed.
 426     /// number of the transient entry readers some time ago
 427     virtual int transientReaders(const StoreEntry &e) const { return 0; }
 428
 429     // XXX: This method belongs to Store::Root/StoreController, but it is here
 430     // to avoid casting Root() to StoreController until Root() API is fixed.
 431     /// disassociates the entry from the intransit table
 432     virtual void transientsDisconnect(MemObject &mem_obj) {}
 433
 434     // XXX: This method belongs to Store::Root/StoreController, but it is here
 435     // to avoid casting Root() to StoreController until Root() API is fixed.
 436     /// removes the entry from the memory cache
 437     virtual void memoryUnlink(StoreEntry &e) {}
 438
 439     // XXX: This method belongs to Store::Root/StoreController, but it is here
 440     // to avoid casting Root() to StoreController until Root() API is fixed.
 441     /// disassociates the entry from the memory cache, preserving cached data
 442     virtual void memoryDisconnect(StoreEntry &e) {}
 443
 444     /// If the entry is not found, return false. Otherwise, return true after
 445     /// tying the entry to this cache and setting inSync to updateCollapsed().
 446     virtual bool anchorCollapsed(StoreEntry &collapsed, bool &inSync) { return false; }
 447
 448     /// update a local collapsed entry with fresh info from this cache (if any)
 449     virtual bool updateCollapsed(StoreEntry &collapsed) { return false; }
 450
 451 private:
 452     static RefCount<Store> CurrentRoot;
 453 };
 454
 455 /// \ingroup StoreAPI
 456 typedef RefCount<Store> StorePointer;
 457
 458 /// \ingroup StoreAPI
 459 size_t storeEntryInUse();
 460
 461 /// \ingroup StoreAPI
 462 const char *storeEntryFlags(const StoreEntry *);
 463
 464 /// \ingroup StoreAPI
 465 void storeEntryReplaceObject(StoreEntry *, HttpReply *);
 466
 467 /// \ingroup StoreAPI
 468 StoreEntry *storeGetPublic(const char *uri, const HttpRequestMethod& method);
 469
 470 /// \ingroup StoreAPI
 471 StoreEntry *storeGetPublicByRequest(HttpRequest * request);
 472
 473 /// \ingroup StoreAPI
 474 StoreEntry *storeGetPublicByRequestMethod(HttpRequest * request, const HttpRequestMethod& method);
 475
 476 /// \ingroup StoreAPI
 477 /// Like storeCreatePureEntry(), but also locks the entry and sets entry key.
 478 StoreEntry *storeCreateEntry(const char *, const char *, const RequestFlags &, const HttpRequestMethod&);
 479
 480 /// \ingroup StoreAPI
 481 /// Creates a new StoreEntry with mem_obj and sets initial flags/states.
 482 StoreEntry *storeCreatePureEntry(const char *storeId, const char *logUrl, const RequestFlags &, const HttpRequestMethod&);
 483
 484 /// \ingroup StoreAPI
 485 void storeInit(void);
 486
 487 /// \ingroup StoreAPI
 488 void storeConfigure(void);
 489
 490 /// \ingroup StoreAPI
 491 void storeFreeMemory(void);
 492
 493 /// \ingroup StoreAPI
 494 int expiresMoreThan(time_t, time_t);
 495
 496 /// \ingroup StoreAPI
 497 void storeAppendPrintf(StoreEntry *, const char *,...) PRINTF_FORMAT_ARG2;
 498
 499 /// \ingroup StoreAPI
 500 void storeAppendVPrintf(StoreEntry *, const char *, va_list ap);
 501
 502 /// \ingroup StoreAPI
 503 int storeTooManyDiskFilesOpen(void);
 504
 505 class SwapDir;
 506 /// \ingroup StoreAPI
 507 void storeHeapPositionUpdate(StoreEntry *, SwapDir *);
 508
 509 /// \ingroup StoreAPI
 510 void storeSwapFileNumberSet(StoreEntry * e, sfileno filn);
 511
 512 /// \ingroup StoreAPI
 513 void storeFsInit(void);
 514
 515 /// \ingroup StoreAPI
 516 void storeFsDone(void);
 517
 518 /// \ingroup StoreAPI
 519 void storeReplAdd(const char *, REMOVALPOLICYCREATE *);
 520
 521 /// \ingroup StoreAPI
 522 extern FREE destroyStoreEntry;
 523
 524 /**
 525  \ingroup StoreAPI
 526  \todo should be a subclass of Packer perhaps ?
 527  */
 528 void packerToStoreInit(Packer * p, StoreEntry * e);
 529
 530 /// \ingroup StoreAPI
 531 void storeGetMemSpace(int size);
 532
 533 #endif /* SQUID_STORE_H */