Source code

Revision control

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 ;*; */
/* vim: set sw=2 ts=8 et tw=80 : */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsAutoPtr.h"
#include "nsIDocShell.h"
#include "mozilla/dom/Document.h"
#include "nsIDocumentLoader.h"
#include "nsIObserverService.h"
#include "nsIXULRuntime.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "RequestContextService.h"

#include "mozilla/Atomics.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/Logging.h"
#include "mozilla/Services.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/TimeStamp.h"

#include "mozilla/net/NeckoChild.h"
#include "mozilla/net/NeckoCommon.h"
#include "mozilla/net/PSpdyPush.h"

#include "../protocol/http/nsHttpHandler.h"

namespace mozilla {
namespace net {

LazyLogModule gRequestContextLog("RequestContext");
#undef LOG
#define LOG(args) MOZ_LOG(gRequestContextLog, LogLevel::Info, args)

static StaticRefPtr<RequestContextService> gSingleton;

// This is used to prevent adding tail pending requests after shutdown
static bool sShutdown = false;

// nsIRequestContext
class RequestContext final : public nsIRequestContext, public nsITimerCallback {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIREQUESTCONTEXT
  NS_DECL_NSITIMERCALLBACK

  explicit RequestContext(const uint64_t id);

 private:
  virtual ~RequestContext();

  void ProcessTailQueue(nsresult aResult);
  // Reschedules the timer if needed
  void ScheduleUnblock();
  // Hard-reschedules the timer
  void RescheduleUntailTimer(TimeStamp const &now);

  uint64_t mID;
  Atomic<uint32_t> mBlockingTransactionCount;
  nsAutoPtr<SpdyPushCache> mSpdyCache;
  nsCString mUserAgentOverride;

  typedef nsCOMPtr<nsIRequestTailUnblockCallback> PendingTailRequest;
  // Number of known opened non-tailed requets
  uint32_t mNonTailRequests;
  // Queue of requests that have been tailed, when conditions are met
  // we call each of them to unblock and drop the reference
  nsTArray<PendingTailRequest> mTailQueue;
  // Loosly scheduled timer, never scheduled further to the future than
  // mUntailAt time
  nsCOMPtr<nsITimer> mUntailTimer;
  // Timestamp when the timer is expected to fire,
  // always less than or equal to mUntailAt
  TimeStamp mTimerScheduledAt;
  // Timestamp when we want to actually untail queued requets based on
  // the number of request count change in the past; iff this timestamp
  // is set, we tail requests
  TimeStamp mUntailAt;

  // Timestamp of the navigation start time, set to Now() in BeginLoad().
  // This is used to progressively lower the maximum delay time so that
  // we can't get to a situation when a number of repetitive requests
  // on the page causes forever tailing.
  TimeStamp mBeginLoadTime;

  // This member is true only between DOMContentLoaded notification and
  // next document load beginning for this request context.
  // Top level request contexts are recycled.
  bool mAfterDOMContentLoaded;
};

NS_IMPL_ISUPPORTS(RequestContext, nsIRequestContext, nsITimerCallback)

RequestContext::RequestContext(const uint64_t aID)
    : mID(aID),
      mBlockingTransactionCount(0),
      mNonTailRequests(0),
      mAfterDOMContentLoaded(false) {
  LOG(("RequestContext::RequestContext this=%p id=%" PRIx64, this, mID));
}

RequestContext::~RequestContext() {
  MOZ_ASSERT(mTailQueue.Length() == 0);

  LOG(("RequestContext::~RequestContext this=%p blockers=%u", this,
       static_cast<uint32_t>(mBlockingTransactionCount)));
}

NS_IMETHODIMP
RequestContext::BeginLoad() {
  MOZ_ASSERT(NS_IsMainThread());

  LOG(("RequestContext::BeginLoad %p", this));

  if (IsNeckoChild()) {
    // Tailing is not supported on the child process
    if (gNeckoChild) {
      gNeckoChild->SendRequestContextLoadBegin(mID);
    }
    return NS_OK;
  }

  mAfterDOMContentLoaded = false;
  mBeginLoadTime = TimeStamp::NowLoRes();
  return NS_OK;
}

NS_IMETHODIMP
RequestContext::DOMContentLoaded() {
  MOZ_ASSERT(NS_IsMainThread());

  LOG(("RequestContext::DOMContentLoaded %p", this));

  if (IsNeckoChild()) {
    // Tailing is not supported on the child process
    if (gNeckoChild) {
      gNeckoChild->SendRequestContextAfterDOMContentLoaded(mID);
    }
    return NS_OK;
  }

  if (mAfterDOMContentLoaded) {
    // There is a possibility of a duplicate notification
    return NS_OK;
  }

  mAfterDOMContentLoaded = true;

  // Conditions for the delay calculation has changed.
  ScheduleUnblock();
  return NS_OK;
}

NS_IMETHODIMP
RequestContext::GetBlockingTransactionCount(
    uint32_t *aBlockingTransactionCount) {
  NS_ENSURE_ARG_POINTER(aBlockingTransactionCount);
  *aBlockingTransactionCount = mBlockingTransactionCount;
  return NS_OK;
}

NS_IMETHODIMP
RequestContext::AddBlockingTransaction() {
  mBlockingTransactionCount++;
  LOG(("RequestContext::AddBlockingTransaction this=%p blockers=%u", this,
       static_cast<uint32_t>(mBlockingTransactionCount)));
  return NS_OK;
}

NS_IMETHODIMP
RequestContext::RemoveBlockingTransaction(uint32_t *outval) {
  NS_ENSURE_ARG_POINTER(outval);
  mBlockingTransactionCount--;
  LOG(("RequestContext::RemoveBlockingTransaction this=%p blockers=%u", this,
       static_cast<uint32_t>(mBlockingTransactionCount)));
  *outval = mBlockingTransactionCount;
  return NS_OK;
}

SpdyPushCache *RequestContext::GetSpdyPushCache() { return mSpdyCache; }

void RequestContext::SetSpdyPushCache(SpdyPushCache *aSpdyPushCache) {
  mSpdyCache = aSpdyPushCache;
}

uint64_t RequestContext::GetID() { return mID; }

const nsACString &RequestContext::GetUserAgentOverride() {
  return mUserAgentOverride;
}

void RequestContext::SetUserAgentOverride(
    const nsACString &aUserAgentOverride) {
  mUserAgentOverride = aUserAgentOverride;
}

NS_IMETHODIMP
RequestContext::AddNonTailRequest() {
  MOZ_ASSERT(NS_IsMainThread());

  ++mNonTailRequests;
  LOG(("RequestContext::AddNonTailRequest this=%p, cnt=%u", this,
       mNonTailRequests));

  ScheduleUnblock();
  return NS_OK;
}

NS_IMETHODIMP
RequestContext::RemoveNonTailRequest() {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(mNonTailRequests > 0);

  LOG(("RequestContext::RemoveNonTailRequest this=%p, cnt=%u", this,
       mNonTailRequests - 1));

  --mNonTailRequests;

  ScheduleUnblock();
  return NS_OK;
}

void RequestContext::ScheduleUnblock() {
  MOZ_ASSERT(!IsNeckoChild());
  MOZ_ASSERT(NS_IsMainThread());

  if (!gHttpHandler) {
    return;
  }

  uint32_t quantum =
      gHttpHandler->TailBlockingDelayQuantum(mAfterDOMContentLoaded);
  uint32_t delayMax = gHttpHandler->TailBlockingDelayMax();
  uint32_t totalMax = gHttpHandler->TailBlockingTotalMax();

  if (!mBeginLoadTime.IsNull()) {
    // We decrease the maximum delay progressively with the time since the page
    // load begin.  This seems like a reasonable and clear heuristic allowing us
    // to start loading tailed requests in a deterministic time after the load
    // has started.

    uint32_t sinceBeginLoad = static_cast<uint32_t>(
        (TimeStamp::NowLoRes() - mBeginLoadTime).ToMilliseconds());
    uint32_t tillTotal = totalMax - std::min(sinceBeginLoad, totalMax);
    uint32_t proportion = totalMax  // values clamped between 0 and 60'000
                              ? (delayMax * tillTotal) / totalMax
                              : 0;
    delayMax = std::min(delayMax, proportion);
  }

  CheckedInt<uint32_t> delay = quantum * mNonTailRequests;

  if (!mAfterDOMContentLoaded) {
    // Before DOMContentLoaded notification we want to make sure that tailed
    // requests don't start when there is a short delay during which we may
    // not have any active requests on the page happening.
    delay += quantum;
  }

  if (!delay.isValid() || delay.value() > delayMax) {
    delay = delayMax;
  }

  LOG(
      ("RequestContext::ScheduleUnblock this=%p non-tails=%u tail-queue=%zu "
       "delay=%u after-DCL=%d",
       this, mNonTailRequests, mTailQueue.Length(), delay.value(),
       mAfterDOMContentLoaded));

  TimeStamp now = TimeStamp::NowLoRes();
  mUntailAt = now + TimeDuration::FromMilliseconds(delay.value());

  if (mTimerScheduledAt.IsNull() || mUntailAt < mTimerScheduledAt) {
    LOG(("RequestContext %p timer would fire too late, rescheduling", this));
    RescheduleUntailTimer(now);
  }
}

void RequestContext::RescheduleUntailTimer(TimeStamp const &now) {
  MOZ_ASSERT(mUntailAt >= now);

  if (mUntailTimer) {
    mUntailTimer->Cancel();
  }

  if (!mTailQueue.Length()) {
    mUntailTimer = nullptr;
    mTimerScheduledAt = TimeStamp();
    return;
  }

  TimeDuration interval = mUntailAt - now;
  if (!mTimerScheduledAt.IsNull() && mUntailAt < mTimerScheduledAt) {
    // When the number of untailed requests goes down,
    // let's half the interval, since it's likely we would
    // reschedule for a shorter time again very soon.
    // This will likely save rescheduling this timer.
    interval = interval / int64_t(2);
    mTimerScheduledAt = mUntailAt - interval;
  } else {
    mTimerScheduledAt = mUntailAt;
  }

  uint32_t delay = interval.ToMilliseconds();
  mUntailTimer = do_CreateInstance("@mozilla.org/timer;1");
  mUntailTimer->InitWithCallback(this, delay, nsITimer::TYPE_ONE_SHOT);

  LOG(("RequestContext::RescheduleUntailTimer %p in %d", this, delay));
}

NS_IMETHODIMP
RequestContext::Notify(nsITimer *timer) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(timer == mUntailTimer);
  MOZ_ASSERT(!mTimerScheduledAt.IsNull());
  MOZ_ASSERT(mTailQueue.Length());

  mUntailTimer = nullptr;

  TimeStamp now = TimeStamp::NowLoRes();
  if (mUntailAt > mTimerScheduledAt && mUntailAt > now) {
    LOG(("RequestContext %p timer fired too soon, rescheduling", this));
    RescheduleUntailTimer(now);
    return NS_OK;
  }

  // Must drop to allow re-engage of the timer
  mTimerScheduledAt = TimeStamp();

  ProcessTailQueue(NS_OK);

  return NS_OK;
}

NS_IMETHODIMP
RequestContext::IsContextTailBlocked(nsIRequestTailUnblockCallback *aRequest,
                                     bool *aBlocked) {
  MOZ_ASSERT(NS_IsMainThread());

  LOG(("RequestContext::IsContextTailBlocked this=%p, request=%p, queued=%zu",
       this, aRequest, mTailQueue.Length()));

  *aBlocked = false;

  if (sShutdown) {
    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
  }

  if (mUntailAt.IsNull()) {
    LOG(("  untail time passed"));
    return NS_OK;
  }

  if (mAfterDOMContentLoaded && !mNonTailRequests) {
    LOG(("  after DOMContentLoaded and no untailed requests"));
    return NS_OK;
  }

  if (!gHttpHandler) {
    // Xpcshell tests may not have http handler
    LOG(("  missing gHttpHandler?"));
    return NS_OK;
  }

  *aBlocked = true;
  mTailQueue.AppendElement(aRequest);

  LOG(("  request queued"));

  if (!mUntailTimer) {
    ScheduleUnblock();
  }

  return NS_OK;
}

NS_IMETHODIMP
RequestContext::CancelTailedRequest(nsIRequestTailUnblockCallback *aRequest) {
  MOZ_ASSERT(NS_IsMainThread());

  bool removed = mTailQueue.RemoveElement(aRequest);

  LOG(("RequestContext::CancelTailedRequest %p req=%p removed=%d", this,
       aRequest, removed));

  // Stop untail timer if all tail requests are canceled.
  if (removed && mTailQueue.IsEmpty()) {
    if (mUntailTimer) {
      mUntailTimer->Cancel();
      mUntailTimer = nullptr;
    }

    // Must drop to allow re-engage of the timer
    mTimerScheduledAt = TimeStamp();
  }

  return NS_OK;
}

void RequestContext::ProcessTailQueue(nsresult aResult) {
  LOG(("RequestContext::ProcessTailQueue this=%p, queued=%zu, rv=%" PRIx32,
       this, mTailQueue.Length(), static_cast<uint32_t>(aResult)));

  if (mUntailTimer) {
    mUntailTimer->Cancel();
    mUntailTimer = nullptr;
  }

  // Must drop to stop tailing requests
  mUntailAt = TimeStamp();

  nsTArray<PendingTailRequest> queue;
  queue.SwapElements(mTailQueue);

  for (const auto &request : queue) {
    LOG(("  untailing %p", request.get()));
    request->OnTailUnblock(aResult);
  }
}

NS_IMETHODIMP
RequestContext::CancelTailPendingRequests(nsresult aResult) {
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(NS_FAILED(aResult));

  ProcessTailQueue(aResult);
  return NS_OK;
}

// nsIRequestContextService
RequestContextService *RequestContextService::sSelf = nullptr;

NS_IMPL_ISUPPORTS(RequestContextService, nsIRequestContextService, nsIObserver)

RequestContextService::RequestContextService()
    : mRCIDNamespace(0), mNextRCID(1) {
  MOZ_ASSERT(!sSelf, "multiple rcs instances!");
  MOZ_ASSERT(NS_IsMainThread());
  sSelf = this;

  nsCOMPtr<nsIXULRuntime> runtime = do_GetService("@mozilla.org/xre/runtime;1");
  runtime->GetProcessID(&mRCIDNamespace);
}

RequestContextService::~RequestContextService() {
  MOZ_ASSERT(NS_IsMainThread());
  Shutdown();
  sSelf = nullptr;
}

nsresult RequestContextService::Init() {
  nsresult rv;

  MOZ_ASSERT(NS_IsMainThread());
  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
  if (!obs) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  rv = obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
  if (NS_FAILED(rv)) {
    return rv;
  }
  obs->AddObserver(this, "content-document-interactive", false);
  if (NS_FAILED(rv)) {
    return rv;
  }

  return NS_OK;
}

void RequestContextService::Shutdown() {
  MOZ_ASSERT(NS_IsMainThread());
  // We need to do this to prevent the requests from being scheduled after
  // shutdown.
  for (auto iter = mTable.Iter(); !iter.Done(); iter.Next()) {
    iter.Data()->CancelTailPendingRequests(NS_ERROR_ABORT);
  }
  mTable.Clear();
  sShutdown = true;
}

/* static */ already_AddRefed<nsIRequestContextService>
RequestContextService::GetOrCreate() {
  MOZ_ASSERT(NS_IsMainThread());

  RefPtr<RequestContextService> svc;
  if (gSingleton) {
    svc = gSingleton;
  } else {
    svc = new RequestContextService();
    nsresult rv = svc->Init();
    NS_ENSURE_SUCCESS(rv, nullptr);
    gSingleton = svc;
    ClearOnShutdown(&gSingleton);
  }

  return svc.forget();
}

NS_IMETHODIMP
RequestContextService::GetRequestContext(const uint64_t rcID,
                                         nsIRequestContext **rc) {
  MOZ_ASSERT(NS_IsMainThread());
  NS_ENSURE_ARG_POINTER(rc);
  *rc = nullptr;

  if (sShutdown) {
    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
  }

  if (!mTable.Get(rcID, rc)) {
    nsCOMPtr<nsIRequestContext> newSC = new RequestContext(rcID);
    mTable.Put(rcID, newSC);
    newSC.swap(*rc);
  }

  return NS_OK;
}

NS_IMETHODIMP
RequestContextService::GetRequestContextFromLoadGroup(nsILoadGroup *aLoadGroup,
                                                      nsIRequestContext **rc) {
  nsresult rv;

  uint64_t rcID;
  rv = aLoadGroup->GetRequestContextID(&rcID);
  if (NS_FAILED(rv)) {
    return rv;
  }

  return GetRequestContext(rcID, rc);
}

NS_IMETHODIMP
RequestContextService::NewRequestContext(nsIRequestContext **rc) {
  MOZ_ASSERT(NS_IsMainThread());
  NS_ENSURE_ARG_POINTER(rc);
  *rc = nullptr;

  if (sShutdown) {
    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
  }

  uint64_t rcID =
      ((static_cast<uint64_t>(mRCIDNamespace) << 32) & 0xFFFFFFFF00000000LL) |
      mNextRCID++;

  nsCOMPtr<nsIRequestContext> newSC = new RequestContext(rcID);
  mTable.Put(rcID, newSC);
  newSC.swap(*rc);

  return NS_OK;
}

NS_IMETHODIMP
RequestContextService::RemoveRequestContext(const uint64_t rcID) {
  if (IsNeckoChild() && gNeckoChild) {
    gNeckoChild->SendRemoveRequestContext(rcID);
  }

  MOZ_ASSERT(NS_IsMainThread());
  mTable.Remove(rcID);
  return NS_OK;
}

NS_IMETHODIMP
RequestContextService::Observe(nsISupports *subject, const char *topic,
                               const char16_t *data_unicode) {
  MOZ_ASSERT(NS_IsMainThread());
  if (!strcmp(NS_XPCOM_SHUTDOWN_OBSERVER_ID, topic)) {
    Shutdown();
    return NS_OK;
  }

  if (!strcmp("content-document-interactive", topic)) {
    nsCOMPtr<dom::Document> document(do_QueryInterface(subject));
    MOZ_ASSERT(document);
    // We want this be triggered also for iframes, since those track their
    // own request context ids.
    if (!document) {
      return NS_OK;
    }
    nsIDocShell *ds = document->GetDocShell();
    // XML documents don't always have a docshell assigned
    if (!ds) {
      return NS_OK;
    }
    nsCOMPtr<nsIDocumentLoader> dl(do_QueryInterface(ds));
    if (!dl) {
      return NS_OK;
    }
    nsCOMPtr<nsILoadGroup> lg;
    dl->GetLoadGroup(getter_AddRefs(lg));
    if (!lg) {
      return NS_OK;
    }
    nsCOMPtr<nsIRequestContext> rc;
    GetRequestContextFromLoadGroup(lg, getter_AddRefs(rc));
    if (rc) {
      rc->DOMContentLoaded();
    }

    return NS_OK;
  }

  MOZ_ASSERT(false, "Unexpected observer topic");
  return NS_OK;
}

}  // namespace net
}  // namespace mozilla

#undef LOG