src/Transients.cc

   1 /*
   2  * Copyright (C) 1996-2017 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 20    Storage Manager */
  10
  11 #include "squid.h"
  12 #include "base/RunnersRegistry.h"
  13 #include "CollapsedForwarding.h"
  14 #include "HttpReply.h"
  15 #include "ipc/mem/Page.h"
  16 #include "ipc/mem/Pages.h"
  17 #include "MemObject.h"
  18 #include "mime_header.h"
  19 #include "SquidConfig.h"
  20 #include "SquidMath.h"
  21 #include "StoreStats.h"
  22 #include "tools.h"
  23 #include "Transients.h"
  24
  25 #include <limits>
  26
  27 /// shared memory segment path to use for Transients map
  28 static const SBuf MapLabel("transients_map");
  29 /// shared memory segment path to use for Transients map extras
  30 static const char *ExtrasLabel = "transients_ex";
  31
  32 Transients::Transients(): map(NULL), locals(NULL)
  33 {
  34 }
  35
  36 Transients::~Transients()
  37 {
  38     delete map;
  39     delete locals;
  40 }
  41
  42 void
  43 Transients::init()
  44 {
  45     const int64_t entryLimit = EntryLimit();
  46     if (entryLimit <= 0)
  47         return; // no SMP support or a misconfiguration
  48
  49     Must(!map);
  50     map = new TransientsMap(MapLabel);
  51     map->cleaner = this;
  52
  53     extras = shm_old(TransientsMapExtras)(ExtrasLabel);
  54
  55     locals = new Locals(entryLimit, 0);
  56 }
  57
  58 void
  59 Transients::getStats(StoreInfoStats &stats) const
  60 {
  61 #if TRANSIENT_STATS_SUPPORTED
  62     const size_t pageSize = Ipc::Mem::PageSize();
  63
  64     stats.mem.shared = true;
  65     stats.mem.capacity =
  66         Ipc::Mem::PageLimit(Ipc::Mem::PageId::cachePage) * pageSize;
  67     stats.mem.size =
  68         Ipc::Mem::PageLevel(Ipc::Mem::PageId::cachePage) * pageSize;
  69     stats.mem.count = currentCount();
  70 #endif
  71 }
  72
  73 void
  74 Transients::stat(StoreEntry &e) const
  75 {
  76     storeAppendPrintf(&e, "\n\nTransient Objects\n");
  77
  78     storeAppendPrintf(&e, "Maximum Size: %.0f KB\n", maxSize()/1024.0);
  79     storeAppendPrintf(&e, "Current Size: %.2f KB %.2f%%\n",
  80                       currentSize() / 1024.0,
  81                       Math::doublePercent(currentSize(), maxSize()));
  82
  83     if (map) {
  84         const int limit = map->entryLimit();
  85         storeAppendPrintf(&e, "Maximum entries: %9d\n", limit);
  86         if (limit > 0) {
  87             storeAppendPrintf(&e, "Current entries: %" PRId64 " %.2f%%\n",
  88                               currentCount(), (100.0 * currentCount() / limit));
  89         }
  90     }
  91 }
  92
  93 void
  94 Transients::maintain()
  95 {
  96     // no lazy garbage collection needed
  97 }
  98
  99 uint64_t
 100 Transients::minSize() const
 101 {
 102     return 0; // XXX: irrelevant, but Store parent forces us to implement this
 103 }
 104
 105 uint64_t
 106 Transients::maxSize() const
 107 {
 108     // Squid currently does not limit the total size of all transient objects
 109     return std::numeric_limits<uint64_t>::max();
 110 }
 111
 112 uint64_t
 113 Transients::currentSize() const
 114 {
 115     // TODO: we do not get enough information to calculate this
 116     // StoreEntry should update associated stores when its size changes
 117     return 0;
 118 }
 119
 120 uint64_t
 121 Transients::currentCount() const
 122 {
 123     return map ? map->entryCount() : 0;
 124 }
 125
 126 int64_t
 127 Transients::maxObjectSize() const
 128 {
 129     // Squid currently does not limit the size of a transient object
 130     return std::numeric_limits<uint64_t>::max();
 131 }
 132
 133 void
 134 Transients::reference(StoreEntry &)
 135 {
 136     // no replacement policy (but the cache(s) storing the entry may have one)
 137 }
 138
 139 bool
 140 Transients::dereference(StoreEntry &)
 141 {
 142     // no need to keep e in the global store_table for us; we have our own map
 143     return false;
 144 }
 145
 146 StoreEntry *
 147 Transients::get(const cache_key *key)
 148 {
 149     if (!map)
 150         return NULL;
 151
 152     sfileno index;
 153     const Ipc::StoreMapAnchor *anchor = map->openForReading(key, index);
 154     if (!anchor)
 155         return NULL;
 156
 157     // If we already have a local entry, the store_table should have found it.
 158     // Since it did not, the local entry key must have changed from public to
 159     // private. We still need to keep the private entry around for syncing as
 160     // its clients depend on it, but we should not allow new clients to join.
 161     if (StoreEntry *oldE = locals->at(index)) {
 162         debugs(20, 3, "not joining private " << *oldE);
 163         assert(EBIT_TEST(oldE->flags, KEY_PRIVATE));
 164     } else if (StoreEntry *newE = copyFromShm(index)) {
 165         return newE; // keep read lock to receive updates from others
 166     }
 167
 168     // private entry or loading failure
 169     map->closeForReading(index);
 170     return NULL;
 171 }
 172
 173 StoreEntry *
 174 Transients::copyFromShm(const sfileno index)
 175 {
 176     const TransientsMapExtras::Item &extra = extras->items[index];
 177
 178     // create a brand new store entry and initialize it with stored info
 179     StoreEntry *e = storeCreatePureEntry(extra.url, extra.url,
 180                                          extra.reqFlags, extra.reqMethod);
 181
 182     assert(e->mem_obj);
 183     e->mem_obj->method = extra.reqMethod;
 184     e->mem_obj->xitTable.io = MemObject::ioReading;
 185     e->mem_obj->xitTable.index = index;
 186
 187     // TODO: Support collapsed revalidation for SMP-aware caches.
 188     e->setPublicKey(ksDefault);
 189     assert(e->key);
 190
 191     // How do we know its SMP- and not just locally-collapsed? A worker gets
 192     // locally-collapsed entries from the local store_table, not Transients.
 193     // TODO: Can we remove smpCollapsed by not syncing non-transient entries?
 194     e->mem_obj->smpCollapsed = true;
 195
 196     assert(!locals->at(index));
 197     // We do not lock e because we do not want to prevent its destruction;
 198     // e is tied to us via mem_obj so we will know when it is destructed.
 199     locals->at(index) = e;
 200     return e;
 201 }
 202
 203 StoreEntry *
 204 Transients::findCollapsed(const sfileno index)
 205 {
 206     if (!map)
 207         return NULL;
 208
 209     if (StoreEntry *oldE = locals->at(index)) {
 210         debugs(20, 5, "found " << *oldE << " at " << index << " in " << MapLabel);
 211         assert(oldE->mem_obj && oldE->mem_obj->xitTable.index == index);
 212         return oldE;
 213     }
 214
 215     debugs(20, 3, "no entry at " << index << " in " << MapLabel);
 216     return NULL;
 217 }
 218
 219 void
 220 Transients::startWriting(StoreEntry *e, const RequestFlags &reqFlags,
 221                          const HttpRequestMethod &reqMethod)
 222 {
 223     assert(e);
 224     assert(e->mem_obj);
 225     assert(e->mem_obj->xitTable.index < 0);
 226
 227     if (!map) {
 228         debugs(20, 5, "No map to add " << *e);
 229         return;
 230     }
 231
 232     sfileno index = 0;
 233     Ipc::StoreMapAnchor *slot = map->openForWriting(reinterpret_cast<const cache_key *>(e->key), index);
 234     if (!slot) {
 235         debugs(20, 5, "collision registering " << *e);
 236         return;
 237     }
 238
 239     try {
 240         if (copyToShm(*e, index, reqFlags, reqMethod)) {
 241             slot->set(*e);
 242             e->mem_obj->xitTable.io = MemObject::ioWriting;
 243             e->mem_obj->xitTable.index = index;
 244             map->startAppending(index);
 245             // keep write lock -- we will be supplying others with updates
 246             return;
 247         }
 248         // fall through to the error handling code
 249     } catch (const std::exception &x) { // TODO: should we catch ... as well?
 250         debugs(20, 2, "error keeping entry " << index <<
 251                ' ' << *e << ": " << x.what());
 252         // fall through to the error handling code
 253     }
 254
 255     map->abortWriting(index);
 256 }
 257
 258 /// copies all relevant local data to shared memory
 259 bool
 260 Transients::copyToShm(const StoreEntry &e, const sfileno index,
 261                       const RequestFlags &reqFlags,
 262                       const HttpRequestMethod &reqMethod)
 263 {
 264     TransientsMapExtras::Item &extra = extras->items[index];
 265
 266     const char *url = e.url();
 267     const size_t urlLen = strlen(url);
 268     Must(urlLen < sizeof(extra.url)); // we have space to store it all, plus 0
 269     strncpy(extra.url, url, sizeof(extra.url));
 270     extra.url[urlLen] = '\0';
 271
 272     extra.reqFlags = reqFlags;
 273
 274     Must(reqMethod != Http::METHOD_OTHER);
 275     extra.reqMethod = reqMethod.id();
 276
 277     return true;
 278 }
 279
 280 void
 281 Transients::noteFreeMapSlice(const Ipc::StoreMapSliceId)
 282 {
 283     // TODO: we should probably find the entry being deleted and abort it
 284 }
 285
 286 void
 287 Transients::abandon(const StoreEntry &e)
 288 {
 289     assert(e.mem_obj && map);
 290     map->freeEntry(e.mem_obj->xitTable.index); // just marks the locked entry
 291     CollapsedForwarding::Broadcast(e);
 292     // We do not unlock the entry now because the problem is most likely with
 293     // the server resource rather than a specific cache writer, so we want to
 294     // prevent other readers from collapsing requests for that resource.
 295 }
 296
 297 bool
 298 Transients::abandoned(const StoreEntry &e) const
 299 {
 300     assert(e.mem_obj);
 301     return abandonedAt(e.mem_obj->xitTable.index);
 302 }
 303
 304 /// whether an in-transit entry at the index is now abandoned by its writer
 305 bool
 306 Transients::abandonedAt(const sfileno index) const
 307 {
 308     assert(map);
 309     return map->readableEntry(index).waitingToBeFreed;
 310 }
 311
 312 void
 313 Transients::completeWriting(const StoreEntry &e)
 314 {
 315     if (e.mem_obj && e.mem_obj->xitTable.index >= 0) {
 316         assert(e.mem_obj->xitTable.io == MemObject::ioWriting);
 317         // there will be no more updates from us after this, so we must prevent
 318         // future readers from joining
 319         map->freeEntry(e.mem_obj->xitTable.index); // just marks the locked entry
 320         map->closeForWriting(e.mem_obj->xitTable.index);
 321         e.mem_obj->xitTable.index = -1;
 322         e.mem_obj->xitTable.io = MemObject::ioDone;
 323     }
 324 }
 325
 326 int
 327 Transients::readers(const StoreEntry &e) const
 328 {
 329     if (e.mem_obj && e.mem_obj->xitTable.index >= 0) {
 330         assert(map);
 331         return map->peekAtEntry(e.mem_obj->xitTable.index).lock.readers;
 332     }
 333     return 0;
 334 }
 335
 336 void
 337 Transients::markForUnlink(StoreEntry &e)
 338 {
 339     unlink(e);
 340 }
 341
 342 void
 343 Transients::unlink(StoreEntry &e)
 344 {
 345     if (e.mem_obj && e.mem_obj->xitTable.io == MemObject::ioWriting)
 346         abandon(e);
 347 }
 348
 349 void
 350 Transients::disconnect(MemObject &mem_obj)
 351 {
 352     if (mem_obj.xitTable.index >= 0) {
 353         assert(map);
 354         if (mem_obj.xitTable.io == MemObject::ioWriting) {
 355             map->abortWriting(mem_obj.xitTable.index);
 356         } else {
 357             assert(mem_obj.xitTable.io == MemObject::ioReading);
 358             map->closeForReading(mem_obj.xitTable.index);
 359         }
 360         locals->at(mem_obj.xitTable.index) = NULL;
 361         mem_obj.xitTable.index = -1;
 362         mem_obj.xitTable.io = MemObject::ioDone;
 363     }
 364 }
 365
 366 /// calculates maximum number of entries we need to store and map
 367 int64_t
 368 Transients::EntryLimit()
 369 {
 370     // TODO: we should also check whether any SMP-aware caching is configured
 371     if (!UsingSmp() || !Config.onoff.collapsed_forwarding)
 372         return 0; // no SMP collapsed forwarding possible or needed
 373
 374     return Config.collapsed_forwarding_shared_entries_limit;
 375 }
 376
 377 /// initializes shared memory segment used by Transients
 378 class TransientsRr: public Ipc::Mem::RegisteredRunner
 379 {
 380 public:
 381     /* RegisteredRunner API */
 382     TransientsRr(): mapOwner(NULL), extrasOwner(NULL) {}
 383     virtual void useConfig();
 384     virtual ~TransientsRr();
 385
 386 protected:
 387     virtual void create();
 388
 389 private:
 390     TransientsMap::Owner *mapOwner;
 391     Ipc::Mem::Owner<TransientsMapExtras> *extrasOwner;
 392 };
 393
 394 RunnerRegistrationEntry(TransientsRr);
 395
 396 void
 397 TransientsRr::useConfig()
 398 {
 399     assert(Config.memShared.configured());
 400     Ipc::Mem::RegisteredRunner::useConfig();
 401 }
 402
 403 void
 404 TransientsRr::create()
 405 {
 406     if (!Config.onoff.collapsed_forwarding)
 407         return;
 408
 409     const int64_t entryLimit = Transients::EntryLimit();
 410     if (entryLimit <= 0)
 411         return; // no SMP configured or a misconfiguration
 412
 413     Must(!mapOwner);
 414     mapOwner = TransientsMap::Init(MapLabel, entryLimit);
 415     Must(!extrasOwner);
 416     extrasOwner = shm_new(TransientsMapExtras)(ExtrasLabel, entryLimit);
 417 }
 418
 419 TransientsRr::~TransientsRr()
 420 {
 421     delete extrasOwner;
 422     delete mapOwner;
 423 }
 424