src/chrome/browser/prerender/prerender_link_manager.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/prerender/prerender_link_manager.h"
   6
   7 #include <functional>
   8 #include <limits>
   9 #include <set>
  10 #include <string>
  11 #include <utility>
  12
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/metrics/field_trial.h"
  15 #include "base/metrics/histogram.h"
  16 #include "chrome/browser/prerender/prerender_contents.h"
  17 #include "chrome/browser/prerender/prerender_handle.h"
  18 #include "chrome/browser/prerender/prerender_manager.h"
  19 #include "chrome/browser/prerender/prerender_manager_factory.h"
  20 #include "chrome/browser/profiles/profile.h"
  21 #include "chrome/common/prerender_messages.h"
  22 #include "chrome/common/prerender_types.h"
  23 #include "content/public/browser/render_process_host.h"
  24 #include "content/public/browser/render_view_host.h"
  25 #include "content/public/browser/session_storage_namespace.h"
  26 #include "content/public/common/referrer.h"
  27 #include "ui/gfx/size.h"
  28 #include "url/gurl.h"
  29
  30 using base::TimeDelta;
  31 using base::TimeTicks;
  32 using content::RenderViewHost;
  33 using content::SessionStorageNamespace;
  34
  35 namespace prerender {
  36
  37 namespace {
  38
  39 bool ShouldStartRelNextPrerenders() {
  40   const std::string experiment_name =
  41       base::FieldTrialList::FindFullName("PrerenderRelNextTrial");
  42
  43   return experiment_name.find("Yes") != std::string::npos;
  44 }
  45
  46 bool ShouldStartPrerender(const uint32 rel_types) {
  47   const bool should_start_rel_next_prerenders =
  48       ShouldStartRelNextPrerenders();
  49
  50   if (rel_types & PrerenderRelTypePrerender) {
  51     return true;
  52   } else if (should_start_rel_next_prerenders &&
  53              (rel_types & PrerenderRelTypeNext) == PrerenderRelTypeNext) {
  54     return true;
  55   }
  56   return false;
  57 }
  58
  59 COMPILE_ASSERT(PrerenderRelTypePrerender == 0x1,
  60                RelTypeHistogramEnum_must_match_PrerenderRelType);
  61 COMPILE_ASSERT(PrerenderRelTypeNext == 0x2,
  62                RelTypeHistogramEnum_must_match_PrerenderRelType);
  63 enum RelTypeHistogramEnum {
  64   RelTypeHistogramEnumNone = 0,
  65   RelTypeHistogramEnumPrerender = PrerenderRelTypePrerender,
  66   RelTypeHistogramEnumNext = PrerenderRelTypeNext,
  67   RelTypeHistogramEnumPrerenderAndNext =
  68       PrerenderRelTypePrerender | PrerenderRelTypeNext,
  69   RelTypeHistogramEnumMax,
  70 };
  71
  72 void RecordLinkManagerAdded(const uint32 rel_types) {
  73   const uint32 enum_value = rel_types & (RelTypeHistogramEnumMax - 1);
  74   UMA_HISTOGRAM_ENUMERATION("Prerender.RelTypesLinkAdded", enum_value,
  75                             RelTypeHistogramEnumMax);
  76 }
  77
  78 void RecordLinkManagerStarting(const uint32 rel_types) {
  79   const uint32 enum_value = rel_types & (RelTypeHistogramEnumMax - 1);
  80   UMA_HISTOGRAM_ENUMERATION("Prerender.RelTypesLinkStarted", enum_value,
  81                             RelTypeHistogramEnumMax);
  82 }
  83
  84 void Send(int child_id, IPC::Message* raw_message) {
  85   using content::RenderProcessHost;
  86   scoped_ptr<IPC::Message> own_message(raw_message);
  87
  88   RenderProcessHost* render_process_host = RenderProcessHost::FromID(child_id);
  89   if (!render_process_host)
  90     return;
  91   render_process_host->Send(own_message.release());
  92 }
  93
  94 }  // namespace
  95
  96 // Helper class to implement PrerenderContents::Observer and watch prerenders
  97 // which launch other prerenders.
  98 class PrerenderLinkManager::PendingPrerenderManager
  99     : public PrerenderContents::Observer {
 100  public:
 101   explicit PendingPrerenderManager(PrerenderLinkManager* link_manager)
 102       : link_manager_(link_manager) {}
 103
 104   virtual ~PendingPrerenderManager() {
 105     DCHECK(observed_launchers_.empty());
 106     for (std::set<PrerenderContents*>::iterator i = observed_launchers_.begin();
 107          i != observed_launchers_.end(); ++i) {
 108       (*i)->RemoveObserver(this);
 109     }
 110   }
 111
 112   void ObserveLauncher(PrerenderContents* launcher) {
 113     DCHECK_EQ(FINAL_STATUS_MAX, launcher->final_status());
 114     if (observed_launchers_.find(launcher) != observed_launchers_.end())
 115       return;
 116     observed_launchers_.insert(launcher);
 117     launcher->AddObserver(this);
 118   }
 119
 120   virtual void OnPrerenderStart(PrerenderContents* launcher) OVERRIDE {}
 121
 122   virtual void OnPrerenderStop(PrerenderContents* launcher) OVERRIDE {
 123     observed_launchers_.erase(launcher);
 124     if (launcher->final_status() == FINAL_STATUS_USED) {
 125       link_manager_->StartPendingPrerendersForLauncher(launcher);
 126     } else {
 127       link_manager_->CancelPendingPrerendersForLauncher(launcher);
 128     }
 129   }
 130
 131  private:
 132   // A pointer to the parent PrerenderLinkManager.
 133   PrerenderLinkManager* link_manager_;
 134
 135   // The set of PrerenderContentses being observed. Lifetimes are managed by
 136   // OnPrerenderStop.
 137   std::set<PrerenderContents*> observed_launchers_;
 138 };
 139
 140 PrerenderLinkManager::PrerenderLinkManager(PrerenderManager* manager)
 141     : has_shutdown_(false),
 142       manager_(manager),
 143       pending_prerender_manager_(new PendingPrerenderManager(this)) {}
 144
 145 PrerenderLinkManager::~PrerenderLinkManager() {
 146   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 147        i != prerenders_.end(); ++i) {
 148     if (i->handle) {
 149       DCHECK(!i->handle->IsPrerendering())
 150           << "All running prerenders should stop at the same time as the "
 151           << "PrerenderManager.";
 152       delete i->handle;
 153       i->handle = 0;
 154     }
 155   }
 156 }
 157
 158 void PrerenderLinkManager::OnAddPrerender(int launcher_child_id,
 159                                           int prerender_id,
 160                                           const GURL& url,
 161                                           uint32 rel_types,
 162                                           const content::Referrer& referrer,
 163                                           const gfx::Size& size,
 164                                           int render_view_route_id) {
 165   DCHECK_EQ(static_cast<LinkPrerender*>(NULL),
 166             FindByLauncherChildIdAndPrerenderId(launcher_child_id,
 167                                                 prerender_id));
 168   content::RenderProcessHost* rph =
 169       content::RenderProcessHost::FromID(launcher_child_id);
 170   // Guests inside <webview> do not support cross-process navigation and so we
 171   // do not allow guests to prerender content.
 172   if (rph && rph->IsGuest())
 173     return;
 174
 175   // Check if the launcher is itself an unswapped prerender.
 176   PrerenderContents* prerender_contents =
 177       manager_->GetPrerenderContentsForRoute(launcher_child_id,
 178                                              render_view_route_id);
 179   if (prerender_contents &&
 180       prerender_contents->final_status() != FINAL_STATUS_MAX) {
 181     // The launcher is a prerender about to be destroyed asynchronously, but
 182     // its AddLinkRelPrerender message raced with shutdown. Ignore it.
 183     DCHECK_NE(FINAL_STATUS_USED, prerender_contents->final_status());
 184     return;
 185   }
 186
 187   LinkPrerender
 188       prerender(launcher_child_id, prerender_id, url, rel_types, referrer, size,
 189                 render_view_route_id, manager_->GetCurrentTimeTicks(),
 190                 prerender_contents);
 191   prerenders_.push_back(prerender);
 192   RecordLinkManagerAdded(rel_types);
 193   if (prerender_contents)
 194     pending_prerender_manager_->ObserveLauncher(prerender_contents);
 195   else
 196     StartPrerenders();
 197 }
 198
 199 void PrerenderLinkManager::OnCancelPrerender(int child_id, int prerender_id) {
 200   LinkPrerender* prerender = FindByLauncherChildIdAndPrerenderId(child_id,
 201                                                                  prerender_id);
 202   if (!prerender)
 203     return;
 204
 205   CancelPrerender(prerender);
 206   StartPrerenders();
 207 }
 208
 209 void PrerenderLinkManager::OnAbandonPrerender(int child_id, int prerender_id) {
 210   LinkPrerender* prerender = FindByLauncherChildIdAndPrerenderId(child_id,
 211                                                                  prerender_id);
 212   if (!prerender)
 213     return;
 214
 215   if (!prerender->handle) {
 216     RemovePrerender(prerender);
 217     return;
 218   }
 219
 220   prerender->has_been_abandoned = true;
 221   prerender->handle->OnNavigateAway();
 222   DCHECK(prerender->handle);
 223
 224   // If the prerender is not running, remove it from the list so it does not
 225   // leak. If it is running, it will send a cancel event when it stops which
 226   // will remove it.
 227   if (!prerender->handle->IsPrerendering())
 228     RemovePrerender(prerender);
 229 }
 230
 231 void PrerenderLinkManager::OnChannelClosing(int child_id) {
 232   std::list<LinkPrerender>::iterator next = prerenders_.begin();
 233   while (next != prerenders_.end()) {
 234     std::list<LinkPrerender>::iterator it = next;
 235     ++next;
 236
 237     if (child_id != it->launcher_child_id)
 238       continue;
 239
 240     const size_t running_prerender_count = CountRunningPrerenders();
 241     OnAbandonPrerender(child_id, it->prerender_id);
 242     DCHECK_EQ(running_prerender_count, CountRunningPrerenders());
 243   }
 244 }
 245
 246 PrerenderLinkManager::LinkPrerender::LinkPrerender(
 247     int launcher_child_id,
 248     int prerender_id,
 249     const GURL& url,
 250     uint32 rel_types,
 251     const content::Referrer& referrer,
 252     const gfx::Size& size,
 253     int render_view_route_id,
 254     TimeTicks creation_time,
 255     PrerenderContents* deferred_launcher)
 256     : launcher_child_id(launcher_child_id),
 257       prerender_id(prerender_id),
 258       url(url),
 259       rel_types(rel_types),
 260       referrer(referrer),
 261       size(size),
 262       render_view_route_id(render_view_route_id),
 263       creation_time(creation_time),
 264       deferred_launcher(deferred_launcher),
 265       handle(NULL),
 266       is_match_complete_replacement(false),
 267       has_been_abandoned(false) {
 268 }
 269
 270 PrerenderLinkManager::LinkPrerender::~LinkPrerender() {
 271   DCHECK_EQ(static_cast<PrerenderHandle*>(NULL), handle)
 272       << "The PrerenderHandle should be destroyed before its Prerender.";
 273 }
 274
 275 bool PrerenderLinkManager::IsEmpty() const {
 276   return prerenders_.empty();
 277 }
 278
 279 size_t PrerenderLinkManager::CountRunningPrerenders() const {
 280   size_t retval = 0;
 281   for (std::list<LinkPrerender>::const_iterator i = prerenders_.begin();
 282        i != prerenders_.end(); ++i) {
 283     if (i->handle && i->handle->IsPrerendering())
 284       ++retval;
 285   }
 286   return retval;
 287 }
 288
 289 void PrerenderLinkManager::StartPrerenders() {
 290   if (has_shutdown_)
 291     return;
 292
 293   size_t total_started_prerender_count = 0;
 294   std::list<LinkPrerender*> abandoned_prerenders;
 295   std::list<std::list<LinkPrerender>::iterator> pending_prerenders;
 296   std::multiset<std::pair<int, int> >
 297       running_launcher_and_render_view_routes;
 298
 299   // Scan the list, counting how many prerenders have handles (and so were added
 300   // to the PrerenderManager). The count is done for the system as a whole, and
 301   // also per launcher.
 302   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 303        i != prerenders_.end(); ++i) {
 304     // Skip prerenders launched by a prerender.
 305     if (i->deferred_launcher)
 306       continue;
 307     if (!i->handle) {
 308       pending_prerenders.push_back(i);
 309     } else {
 310       ++total_started_prerender_count;
 311       if (i->has_been_abandoned) {
 312         abandoned_prerenders.push_back(&(*i));
 313       } else {
 314         // We do not count abandoned prerenders towards their launcher, since it
 315         // has already navigated on to another page.
 316         std::pair<int, int> launcher_and_render_view_route(
 317             i->launcher_child_id, i->render_view_route_id);
 318         running_launcher_and_render_view_routes.insert(
 319             launcher_and_render_view_route);
 320         DCHECK_GE(manager_->config().max_link_concurrency_per_launcher,
 321                   running_launcher_and_render_view_routes.count(
 322                       launcher_and_render_view_route));
 323       }
 324     }
 325
 326     DCHECK_EQ(&(*i), FindByLauncherChildIdAndPrerenderId(i->launcher_child_id,
 327                                                          i->prerender_id));
 328   }
 329   DCHECK_LE(abandoned_prerenders.size(), total_started_prerender_count);
 330   DCHECK_GE(manager_->config().max_link_concurrency,
 331             total_started_prerender_count);
 332   DCHECK_LE(CountRunningPrerenders(), total_started_prerender_count);
 333
 334   TimeTicks now = manager_->GetCurrentTimeTicks();
 335
 336   // Scan the pending prerenders, starting prerenders as we can.
 337   for (std::list<std::list<LinkPrerender>::iterator>::const_iterator
 338            i = pending_prerenders.begin(), end = pending_prerenders.end();
 339        i != end; ++i) {
 340     TimeDelta prerender_age = now - (*i)->creation_time;
 341     if (prerender_age >= manager_->config().max_wait_to_launch) {
 342       // This prerender waited too long in the queue before launching.
 343       prerenders_.erase(*i);
 344       continue;
 345     }
 346
 347     std::pair<int, int> launcher_and_render_view_route(
 348         (*i)->launcher_child_id, (*i)->render_view_route_id);
 349     if (manager_->config().max_link_concurrency_per_launcher <=
 350         running_launcher_and_render_view_routes.count(
 351             launcher_and_render_view_route)) {
 352       // This prerender's launcher is already at its limit.
 353       continue;
 354     }
 355
 356     if (total_started_prerender_count >=
 357             manager_->config().max_link_concurrency ||
 358         total_started_prerender_count >= prerenders_.size()) {
 359       // The system is already at its prerender concurrency limit. Can we kill
 360       // an abandoned prerender to make room?
 361       if (!abandoned_prerenders.empty()) {
 362         CancelPrerender(abandoned_prerenders.front());
 363         --total_started_prerender_count;
 364         abandoned_prerenders.pop_front();
 365       } else {
 366         return;
 367       }
 368     }
 369
 370     if (!ShouldStartPrerender((*i)->rel_types)) {
 371       prerenders_.erase(*i);
 372       continue;
 373     }
 374
 375     PrerenderHandle* handle = manager_->AddPrerenderFromLinkRelPrerender(
 376         (*i)->launcher_child_id, (*i)->render_view_route_id,
 377         (*i)->url, (*i)->rel_types, (*i)->referrer, (*i)->size);
 378     if (!handle) {
 379       // This prerender couldn't be launched, it's gone.
 380       prerenders_.erase(*i);
 381       continue;
 382     }
 383
 384     // We have successfully started a new prerender.
 385     (*i)->handle = handle;
 386     ++total_started_prerender_count;
 387     handle->SetObserver(this);
 388     if (handle->IsPrerendering())
 389       OnPrerenderStart(handle);
 390     RecordLinkManagerStarting((*i)->rel_types);
 391
 392     running_launcher_and_render_view_routes.insert(
 393         launcher_and_render_view_route);
 394   }
 395 }
 396
 397 PrerenderLinkManager::LinkPrerender*
 398 PrerenderLinkManager::FindByLauncherChildIdAndPrerenderId(int launcher_child_id,
 399                                                           int prerender_id) {
 400   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 401        i != prerenders_.end(); ++i) {
 402     if (launcher_child_id == i->launcher_child_id &&
 403         prerender_id == i->prerender_id) {
 404       return &(*i);
 405     }
 406   }
 407   return NULL;
 408 }
 409
 410 PrerenderLinkManager::LinkPrerender*
 411 PrerenderLinkManager::FindByPrerenderHandle(PrerenderHandle* prerender_handle) {
 412   DCHECK(prerender_handle);
 413   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 414        i != prerenders_.end(); ++i) {
 415     if (prerender_handle == i->handle)
 416       return &(*i);
 417   }
 418   return NULL;
 419 }
 420
 421 void PrerenderLinkManager::RemovePrerender(LinkPrerender* prerender) {
 422   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 423        i != prerenders_.end(); ++i) {
 424     if (&(*i) == prerender) {
 425       scoped_ptr<PrerenderHandle> own_handle(i->handle);
 426       i->handle = NULL;
 427       prerenders_.erase(i);
 428       return;
 429     }
 430   }
 431   NOTREACHED();
 432 }
 433
 434 void PrerenderLinkManager::CancelPrerender(LinkPrerender* prerender) {
 435   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 436        i != prerenders_.end(); ++i) {
 437     if (&(*i) == prerender) {
 438       scoped_ptr<PrerenderHandle> own_handle(i->handle);
 439       i->handle = NULL;
 440       prerenders_.erase(i);
 441       if (own_handle)
 442         own_handle->OnCancel();
 443       return;
 444     }
 445   }
 446   NOTREACHED();
 447 }
 448
 449 void PrerenderLinkManager::StartPendingPrerendersForLauncher(
 450     PrerenderContents* launcher) {
 451   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 452        i != prerenders_.end(); ++i) {
 453     if (i->deferred_launcher == launcher)
 454       i->deferred_launcher = NULL;
 455   }
 456   StartPrerenders();
 457 }
 458
 459 void PrerenderLinkManager::CancelPendingPrerendersForLauncher(
 460     PrerenderContents* launcher) {
 461   // Remove all pending prerenders for this launcher.
 462   std::vector<std::list<LinkPrerender>::iterator> to_erase;
 463   for (std::list<LinkPrerender>::iterator i = prerenders_.begin();
 464        i != prerenders_.end(); ++i) {
 465     if (i->deferred_launcher == launcher) {
 466       DCHECK(!i->handle);
 467       to_erase.push_back(i);
 468     }
 469   }
 470   std::for_each(to_erase.begin(), to_erase.end(),
 471                 std::bind1st(std::mem_fun(&std::list<LinkPrerender>::erase),
 472                              &prerenders_));
 473 }
 474
 475 void PrerenderLinkManager::Shutdown() {
 476   has_shutdown_ = true;
 477 }
 478
 479 // In practice, this is always called from PrerenderLinkManager::OnAddPrerender.
 480 void PrerenderLinkManager::OnPrerenderStart(
 481     PrerenderHandle* prerender_handle) {
 482   LinkPrerender* prerender = FindByPrerenderHandle(prerender_handle);
 483   if (!prerender)
 484     return;
 485   Send(prerender->launcher_child_id,
 486        new PrerenderMsg_OnPrerenderStart(prerender->prerender_id));
 487 }
 488
 489 void PrerenderLinkManager::OnPrerenderStopLoading(
 490     PrerenderHandle* prerender_handle) {
 491   LinkPrerender* prerender = FindByPrerenderHandle(prerender_handle);
 492   if (!prerender)
 493     return;
 494
 495   Send(prerender->launcher_child_id,
 496        new PrerenderMsg_OnPrerenderStopLoading(prerender->prerender_id));
 497 }
 498
 499 void PrerenderLinkManager::OnPrerenderDomContentLoaded(
 500     PrerenderHandle* prerender_handle) {
 501   LinkPrerender* prerender = FindByPrerenderHandle(prerender_handle);
 502   if (!prerender)
 503     return;
 504
 505   Send(prerender->launcher_child_id,
 506        new PrerenderMsg_OnPrerenderDomContentLoaded(prerender->prerender_id));
 507 }
 508
 509 void PrerenderLinkManager::OnPrerenderStop(
 510     PrerenderHandle* prerender_handle) {
 511   LinkPrerender* prerender = FindByPrerenderHandle(prerender_handle);
 512   if (!prerender)
 513     return;
 514
 515   // If the prerender became a match complete replacement, the stop
 516   // message has already been sent.
 517   if (!prerender->is_match_complete_replacement) {
 518     Send(prerender->launcher_child_id,
 519          new PrerenderMsg_OnPrerenderStop(prerender->prerender_id));
 520   }
 521   RemovePrerender(prerender);
 522   StartPrerenders();
 523 }
 524
 525 void PrerenderLinkManager::OnPrerenderCreatedMatchCompleteReplacement(
 526     PrerenderHandle* prerender_handle) {
 527   LinkPrerender* prerender = FindByPrerenderHandle(prerender_handle);
 528   if (!prerender)
 529     return;
 530
 531   DCHECK(!prerender->is_match_complete_replacement);
 532   prerender->is_match_complete_replacement = true;
 533   Send(prerender->launcher_child_id,
 534        new PrerenderMsg_OnPrerenderStop(prerender->prerender_id));
 535   // Do not call RemovePrerender here. The replacement needs to stay connected
 536   // to the HTMLLinkElement in the renderer so it notices renderer-triggered
 537   // cancelations.
 538 }
 539
 540 }  // namespace prerender