/src/mozilla-central/netwerk/cache2/CacheEntry.cpp

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/* 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 "CacheLog.h"
#include "CacheEntry.h"
#include "CacheStorageService.h"
#include "CacheObserver.h"
#include "CacheFileUtils.h"
#include "CacheIndex.h"

#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsISeekableStream.h"
#include "nsIURI.h"
#include "nsICacheEntryOpenCallback.h"
#include "nsICacheStorage.h"
#include "nsISerializable.h"
#include "nsIStreamTransportService.h"
#include "nsISizeOf.h"

#include "nsComponentManagerUtils.h"
#include "nsServiceManagerUtils.h"
#include "nsString.h"
#include "nsProxyRelease.h"
#include "nsSerializationHelper.h"
#include "nsThreadUtils.h"
#include "mozilla/Telemetry.h"
#include "mozilla/IntegerPrintfMacros.h"
#include <math.h>
#include <algorithm>

namespace mozilla {
namespace net {

static uint32_t const ENTRY_WANTED =
  nsICacheEntryOpenCallback::ENTRY_WANTED;
static uint32_t const RECHECK_AFTER_WRITE_FINISHED =
  nsICacheEntryOpenCallback::RECHECK_AFTER_WRITE_FINISHED;
static uint32_t const ENTRY_NEEDS_REVALIDATION =
  nsICacheEntryOpenCallback::ENTRY_NEEDS_REVALIDATION;
static uint32_t const ENTRY_NOT_WANTED =
  nsICacheEntryOpenCallback::ENTRY_NOT_WANTED;

NS_IMPL_ISUPPORTS(CacheEntryHandle, nsICacheEntry)

// CacheEntryHandle

CacheEntryHandle::CacheEntryHandle(CacheEntry* aEntry)
: mEntry(aEntry)
, mClosed(false)
{
#ifdef DEBUG
  if (!mEntry->HandlesCount()) {
    // CacheEntry.mHandlesCount must go from zero to one only under
    // the service lock. Can access CacheStorageService::Self() w/o a check
    // since CacheEntry hrefs it.
    CacheStorageService::Self()->Lock().AssertCurrentThreadOwns();
  }
#endif

  mEntry->AddHandleRef();

  LOG(("New CacheEntryHandle %p for entry %p", this, aEntry));
}

NS_IMETHODIMP CacheEntryHandle::Dismiss()
{
  LOG(("CacheEntryHandle::Dismiss %p", this));

  if (mClosed.compareExchange(false, true)) {
    mEntry->OnHandleClosed(this);
    return NS_OK;
  }

  LOG(("  already dropped"));
  return NS_ERROR_UNEXPECTED;
}

CacheEntryHandle::~CacheEntryHandle()
{
  mEntry->ReleaseHandleRef();
  Dismiss();

  LOG(("CacheEntryHandle::~CacheEntryHandle %p", this));
}

// CacheEntry::Callback

CacheEntry::Callback::Callback(CacheEntry* aEntry,
                               nsICacheEntryOpenCallback *aCallback,
                               bool aReadOnly, bool aCheckOnAnyThread,
                               bool aSecret)
: mEntry(aEntry)
, mCallback(aCallback)
, mTarget(GetCurrentThreadEventTarget())
, mReadOnly(aReadOnly)
, mRevalidating(false)
, mCheckOnAnyThread(aCheckOnAnyThread)
, mRecheckAfterWrite(false)
, mNotWanted(false)
, mSecret(aSecret)
, mDoomWhenFoundPinned(false)
, mDoomWhenFoundNonPinned(false)
{
  MOZ_COUNT_CTOR(CacheEntry::Callback);

  // The counter may go from zero to non-null only under the service lock
  // but here we expect it to be already positive.
  MOZ_ASSERT(mEntry->HandlesCount());
  mEntry->AddHandleRef();
}

CacheEntry::Callback::Callback(CacheEntry* aEntry, bool aDoomWhenFoundInPinStatus)
: mEntry(aEntry)
, mReadOnly(false)
, mRevalidating(false)
, mCheckOnAnyThread(true)
, mRecheckAfterWrite(false)
, mNotWanted(false)
, mSecret(false)
, mDoomWhenFoundPinned(aDoomWhenFoundInPinStatus == true)
, mDoomWhenFoundNonPinned(aDoomWhenFoundInPinStatus == false)
{
  MOZ_COUNT_CTOR(CacheEntry::Callback);
  MOZ_ASSERT(mEntry->HandlesCount());
  mEntry->AddHandleRef();
}

CacheEntry::Callback::Callback(CacheEntry::Callback const &aThat)
: mEntry(aThat.mEntry)
, mCallback(aThat.mCallback)
, mTarget(aThat.mTarget)
, mReadOnly(aThat.mReadOnly)
, mRevalidating(aThat.mRevalidating)
, mCheckOnAnyThread(aThat.mCheckOnAnyThread)
, mRecheckAfterWrite(aThat.mRecheckAfterWrite)
, mNotWanted(aThat.mNotWanted)
, mSecret(aThat.mSecret)
, mDoomWhenFoundPinned(aThat.mDoomWhenFoundPinned)
, mDoomWhenFoundNonPinned(aThat.mDoomWhenFoundNonPinned)
{
  MOZ_COUNT_CTOR(CacheEntry::Callback);

  // The counter may go from zero to non-null only under the service lock
  // but here we expect it to be already positive.
  MOZ_ASSERT(mEntry->HandlesCount());
  mEntry->AddHandleRef();
}

CacheEntry::Callback::~Callback()
{
  ProxyRelease("CacheEntry::Callback::mCallback", mCallback, mTarget);

  mEntry->ReleaseHandleRef();
  MOZ_COUNT_DTOR(CacheEntry::Callback);
}

void CacheEntry::Callback::ExchangeEntry(CacheEntry* aEntry)
{
  if (mEntry == aEntry)
    return;

  // The counter may go from zero to non-null only under the service lock
  // but here we expect it to be already positive.
  MOZ_ASSERT(aEntry->HandlesCount());
  aEntry->AddHandleRef();
  mEntry->ReleaseHandleRef();
  mEntry = aEntry;
}

bool CacheEntry::Callback::DeferDoom(bool *aDoom) const
{
  MOZ_ASSERT(mEntry->mPinningKnown);

  if (MOZ_UNLIKELY(mDoomWhenFoundNonPinned) || MOZ_UNLIKELY(mDoomWhenFoundPinned)) {
    *aDoom = (MOZ_UNLIKELY(mDoomWhenFoundNonPinned) && MOZ_LIKELY(!mEntry->mPinned)) ||
             (MOZ_UNLIKELY(mDoomWhenFoundPinned) && MOZ_UNLIKELY(mEntry->mPinned));

    return true;
  }

  return false;
}

nsresult CacheEntry::Callback::OnCheckThread(bool *aOnCheckThread) const
{
  if (!mCheckOnAnyThread) {
    // Check we are on the target
    return mTarget->IsOnCurrentThread(aOnCheckThread);
  }

  // We can invoke check anywhere
  *aOnCheckThread = true;
  return NS_OK;
}

nsresult CacheEntry::Callback::OnAvailThread(bool *aOnAvailThread) const
{
  return mTarget->IsOnCurrentThread(aOnAvailThread);
}

// CacheEntry

NS_IMPL_ISUPPORTS(CacheEntry,
                  nsIRunnable,
                  CacheFileListener)

/* static */
uint64_t CacheEntry::GetNextId()
{
  static Atomic<uint64_t, Relaxed> id(0);
  return ++id;
}

CacheEntry::CacheEntry(const nsACString& aStorageID,
                       const nsACString& aURI,
                       const nsACString& aEnhanceID,
                       bool aUseDisk,
                       bool aSkipSizeCheck,
                       bool aPin)
: mFrecency(0)
, mSortingExpirationTime(uint32_t(-1))
, mLock("CacheEntry")
, mFileStatus(NS_ERROR_NOT_INITIALIZED)
, mURI(aURI)
, mEnhanceID(aEnhanceID)
, mStorageID(aStorageID)
, mUseDisk(aUseDisk)
, mSkipSizeCheck(aSkipSizeCheck)
, mIsDoomed(false)
, mSecurityInfoLoaded(false)
, mPreventCallbacks(false)
, mHasData(false)
, mPinned(aPin)
, mPinningKnown(false)
, mState(NOTLOADED)
, mRegistration(NEVERREGISTERED)
, mWriter(nullptr)
, mUseCount(0)
, mCacheEntryId(GetNextId())
{
  LOG(("CacheEntry::CacheEntry [this=%p]", this));

  mService = CacheStorageService::Self();

  CacheStorageService::Self()->RecordMemoryOnlyEntry(
    this, !aUseDisk, true /* overwrite */);
}

CacheEntry::~CacheEntry()
{
  LOG(("CacheEntry::~CacheEntry [this=%p]", this));
}

char const * CacheEntry::StateString(uint32_t aState)
{
  switch (aState) {
  case NOTLOADED:     return "NOTLOADED";
  case LOADING:       return "LOADING";
  case EMPTY:         return "EMPTY";
  case WRITING:       return "WRITING";
  case READY:         return "READY";
  case REVALIDATING:  return "REVALIDATING";
  }

  return "?";
}

nsresult CacheEntry::HashingKeyWithStorage(nsACString &aResult) const
{
  return HashingKey(mStorageID, mEnhanceID, mURI, aResult);
}

nsresult CacheEntry::HashingKey(nsACString &aResult) const
{
  return HashingKey(EmptyCString(), mEnhanceID, mURI, aResult);
}

// static
nsresult CacheEntry::HashingKey(const nsACString& aStorageID,
                                const nsACString& aEnhanceID,
                                nsIURI* aURI,
                                nsACString &aResult)
{
  nsAutoCString spec;
  nsresult rv = aURI->GetAsciiSpec(spec);
  NS_ENSURE_SUCCESS(rv, rv);

  return HashingKey(aStorageID, aEnhanceID, spec, aResult);
}

// static
nsresult CacheEntry::HashingKey(const nsACString& aStorageID,
                                const nsACString& aEnhanceID,
                                const nsACString& aURISpec,
                                nsACString &aResult)
{
  /**
   * This key is used to salt hash that is a base for disk file name.
   * Changing it will cause we will not be able to find files on disk.
   */

  aResult.Assign(aStorageID);

  if (!aEnhanceID.IsEmpty()) {
    CacheFileUtils::AppendTagWithValue(aResult, '~', aEnhanceID);
  }

  // Appending directly
  aResult.Append(':');
  aResult.Append(aURISpec);

  return NS_OK;
}

void CacheEntry::AsyncOpen(nsICacheEntryOpenCallback* aCallback, uint32_t aFlags)
{
  LOG(("CacheEntry::AsyncOpen [this=%p, state=%s, flags=%d, callback=%p]",
    this, StateString(mState), aFlags, aCallback));

  bool readonly = aFlags & nsICacheStorage::OPEN_READONLY;
  bool bypassIfBusy = aFlags & nsICacheStorage::OPEN_BYPASS_IF_BUSY;
  bool truncate = aFlags & nsICacheStorage::OPEN_TRUNCATE;
  bool priority = aFlags & nsICacheStorage::OPEN_PRIORITY;
  bool multithread = aFlags & nsICacheStorage::CHECK_MULTITHREADED;
  bool secret = aFlags & nsICacheStorage::OPEN_SECRETLY;

  MOZ_ASSERT(!readonly || !truncate, "Bad flags combination");
  MOZ_ASSERT(!(truncate && mState > LOADING), "Must not call truncate on already loaded entry");

  Callback callback(this, aCallback, readonly, multithread, secret);

  if (!Open(callback, truncate, priority, bypassIfBusy)) {
    // We get here when the callback wants to bypass cache when it's busy.
    LOG(("  writing or revalidating, callback wants to bypass cache"));
    callback.mNotWanted = true;
    InvokeAvailableCallback(callback);
  }
}

bool CacheEntry::Open(Callback & aCallback, bool aTruncate,
                      bool aPriority, bool aBypassIfBusy)
{
  mozilla::MutexAutoLock lock(mLock);

  // Check state under the lock
  if (aBypassIfBusy && (mState == WRITING || mState == REVALIDATING)) {
    return false;
  }

  RememberCallback(aCallback);

  // Load() opens the lock
  if (Load(aTruncate, aPriority)) {
    // Loading is in progress...
    return true;
  }

  InvokeCallbacks();

  return true;
}

bool CacheEntry::Load(bool aTruncate, bool aPriority)
{
  LOG(("CacheEntry::Load [this=%p, trunc=%d]", this, aTruncate));

  mLock.AssertCurrentThreadOwns();

  if (mState > LOADING) {
    LOG(("  already loaded"));
    return false;
  }

  if (mState == LOADING) {
    LOG(("  already loading"));
    return true;
  }

  mState = LOADING;

  MOZ_ASSERT(!mFile);

  nsresult rv;

  nsAutoCString fileKey;
  rv = HashingKeyWithStorage(fileKey);

  bool reportMiss = false;

  // Check the index under two conditions for two states and take appropriate action:
  // 1. When this is a disk entry and not told to truncate, check there is a disk file.
  //    If not, set the 'truncate' flag to true so that this entry will open instantly
  //    as a new one.
  // 2. When this is a memory-only entry, check there is a disk file.
  //    If there is or could be, doom that file.
  if ((!aTruncate || !mUseDisk) && NS_SUCCEEDED(rv)) {
    // Check the index right now to know we have or have not the entry
    // as soon as possible.
    CacheIndex::EntryStatus status;
    if (NS_SUCCEEDED(CacheIndex::HasEntry(fileKey, &status))) {
      switch (status) {
      case CacheIndex::DOES_NOT_EXIST:
        // Doesn't apply to memory-only entries, Load() is called only once for them
        // and never again for their session lifetime.
        if (!aTruncate && mUseDisk) {
          LOG(("  entry doesn't exist according information from the index, truncating"));
          reportMiss = true;
          aTruncate = true;
        }
        break;
      case CacheIndex::EXISTS:
      case CacheIndex::DO_NOT_KNOW:
        if (!mUseDisk) {
          LOG(("  entry open as memory-only, but there is a file, status=%d, dooming it", status));
          CacheFileIOManager::DoomFileByKey(fileKey, nullptr);
        }
        break;
      }
    }
  }

  mFile = new CacheFile();

  BackgroundOp(Ops::REGISTER);

  bool directLoad = aTruncate || !mUseDisk;
  if (directLoad) {
    // mLoadStart will be used to calculate telemetry of life-time of this entry.
    // Low resulution is then enough.
    mLoadStart = TimeStamp::NowLoRes();
    mPinningKnown = true;
  } else {
    mLoadStart = TimeStamp::Now();
  }

  {
    mozilla::MutexAutoUnlock unlock(mLock);

    if (reportMiss) {
      CacheFileUtils::DetailedCacheHitTelemetry::AddRecord(
        CacheFileUtils::DetailedCacheHitTelemetry::MISS, mLoadStart);
    }

    LOG(("  performing load, file=%p", mFile.get()));
    if (NS_SUCCEEDED(rv)) {
      rv = mFile->Init(fileKey,
                       aTruncate,
                       !mUseDisk,
                       mSkipSizeCheck,
                       aPriority,
                       mPinned,
                       directLoad ? nullptr : this);
    }

    if (NS_FAILED(rv)) {
      mFileStatus = rv;
      AsyncDoom(nullptr);
      return false;
    }
  }

  if (directLoad) {
    // Just fake the load has already been done as "new".
    mFileStatus = NS_OK;
    mState = EMPTY;
  }

  return mState == LOADING;
}

NS_IMETHODIMP CacheEntry::OnFileReady(nsresult aResult, bool aIsNew)
{
  LOG(("CacheEntry::OnFileReady [this=%p, rv=0x%08" PRIx32 ", new=%d]",
       this, static_cast<uint32_t>(aResult), aIsNew));

  MOZ_ASSERT(!mLoadStart.IsNull());

  if (NS_SUCCEEDED(aResult)) {
    if (aIsNew) {
      CacheFileUtils::DetailedCacheHitTelemetry::AddRecord(
        CacheFileUtils::DetailedCacheHitTelemetry::MISS, mLoadStart);
    } else {
      CacheFileUtils::DetailedCacheHitTelemetry::AddRecord(
        CacheFileUtils::DetailedCacheHitTelemetry::HIT, mLoadStart);
    }
  }

  // OnFileReady, that is the only code that can transit from LOADING
  // to any follow-on state and can only be invoked ones on an entry.
  // Until this moment there is no consumer that could manipulate
  // the entry state.

  mozilla::MutexAutoLock lock(mLock);

  MOZ_ASSERT(mState == LOADING);

  mState = (aIsNew || NS_FAILED(aResult))
    ? EMPTY
    : READY;

  mFileStatus = aResult;

  mPinned = mFile->IsPinned();;
  mPinningKnown = true;
  LOG(("  pinning=%d", mPinned));

  if (mState == READY) {
    mHasData = true;

    uint32_t frecency;
    mFile->GetFrecency(&frecency);
    // mFrecency is held in a double to increase computance precision.
    // It is ok to persist frecency only as a uint32 with some math involved.
    mFrecency = INT2FRECENCY(frecency);
  }

  InvokeCallbacks();

  return NS_OK;
}

NS_IMETHODIMP CacheEntry::OnFileDoomed(nsresult aResult)
{
  if (mDoomCallback) {
    RefPtr<DoomCallbackRunnable> event =
      new DoomCallbackRunnable(this, aResult);
    NS_DispatchToMainThread(event);
  }

  return NS_OK;
}

already_AddRefed<CacheEntryHandle> CacheEntry::ReopenTruncated(bool aMemoryOnly,
                                                               nsICacheEntryOpenCallback* aCallback)
{
  LOG(("CacheEntry::ReopenTruncated [this=%p]", this));

  mLock.AssertCurrentThreadOwns();

  // Hold callbacks invocation, AddStorageEntry would invoke from doom prematurly
  mPreventCallbacks = true;

  RefPtr<CacheEntryHandle> handle;
  RefPtr<CacheEntry> newEntry;
  {
    if (mPinned) {
      MOZ_ASSERT(mUseDisk);
      // We want to pin even no-store entries (the case we recreate a disk entry as
      // a memory-only entry.)
      aMemoryOnly = false;
    }

    mozilla::MutexAutoUnlock unlock(mLock);

    // The following call dooms this entry (calls DoomAlreadyRemoved on us)
    nsresult rv = CacheStorageService::Self()->AddStorageEntry(
      GetStorageID(), GetURI(), GetEnhanceID(),
      mUseDisk && !aMemoryOnly,
      mSkipSizeCheck,
      mPinned,
      true, // truncate existing (this one)
      getter_AddRefs(handle));

    if (NS_SUCCEEDED(rv)) {
      newEntry = handle->Entry();
      LOG(("  exchanged entry %p by entry %p, rv=0x%08" PRIx32,
           this, newEntry.get(), static_cast<uint32_t>(rv)));
      newEntry->AsyncOpen(aCallback, nsICacheStorage::OPEN_TRUNCATE);
    } else {
      LOG(("  exchanged of entry %p failed, rv=0x%08" PRIx32,
           this, static_cast<uint32_t>(rv)));
      AsyncDoom(nullptr);
    }
  }

  mPreventCallbacks = false;

  if (!newEntry)
    return nullptr;

  newEntry->TransferCallbacks(*this);
  mCallbacks.Clear();

  // Must return a new write handle, since the consumer is expected to
  // write to this newly recreated entry.  The |handle| is only a common
  // reference counter and doesn't revert entry state back when write
  // fails and also doesn't update the entry frecency.  Not updating
  // frecency causes entries to not be purged from our memory pools.
  RefPtr<CacheEntryHandle> writeHandle =
    newEntry->NewWriteHandle();
  return writeHandle.forget();
}

void CacheEntry::TransferCallbacks(CacheEntry & aFromEntry)
{
  mozilla::MutexAutoLock lock(mLock);

  LOG(("CacheEntry::TransferCallbacks [entry=%p, from=%p]",
    this, &aFromEntry));

  if (!mCallbacks.Length())
    mCallbacks.SwapElements(aFromEntry.mCallbacks);
  else
    mCallbacks.AppendElements(aFromEntry.mCallbacks);

  uint32_t callbacksLength = mCallbacks.Length();
  if (callbacksLength) {
    // Carry the entry reference (unfortunately, needs to be done manually...)
    for (uint32_t i = 0; i < callbacksLength; ++i)
      mCallbacks[i].ExchangeEntry(this);

    BackgroundOp(Ops::CALLBACKS, true);
  }
}

void CacheEntry::RememberCallback(Callback & aCallback)
{
  mLock.AssertCurrentThreadOwns();

  LOG(("CacheEntry::RememberCallback [this=%p, cb=%p, state=%s]",
    this, aCallback.mCallback.get(), StateString(mState)));

  mCallbacks.AppendElement(aCallback);
}

void CacheEntry::InvokeCallbacksLock()
{
  mozilla::MutexAutoLock lock(mLock);
  InvokeCallbacks();
}

void CacheEntry::InvokeCallbacks()
{
  mLock.AssertCurrentThreadOwns();

  LOG(("CacheEntry::InvokeCallbacks BEGIN [this=%p]", this));

  // Invoke first all r/w callbacks, then all r/o callbacks.
  if (InvokeCallbacks(false))
    InvokeCallbacks(true);

  LOG(("CacheEntry::InvokeCallbacks END [this=%p]", this));
}

bool CacheEntry::InvokeCallbacks(bool aReadOnly)
{
  mLock.AssertCurrentThreadOwns();

  RefPtr<CacheEntryHandle> recreatedHandle;

  uint32_t i = 0;
  while (i < mCallbacks.Length()) {
    if (mPreventCallbacks) {
      LOG(("  callbacks prevented!"));
      return false;
    }

    if (!mIsDoomed && (mState == WRITING || mState == REVALIDATING)) {
      LOG(("  entry is being written/revalidated"));
      return false;
    }

    bool recreate;
    if (mCallbacks[i].DeferDoom(&recreate)) {
      mCallbacks.RemoveElementAt(i);
      if (!recreate) {
        continue;
      }

      LOG(("  defer doom marker callback hit positive, recreating"));
      recreatedHandle = ReopenTruncated(!mUseDisk, nullptr);
      break;
    }

    if (mCallbacks[i].mReadOnly != aReadOnly) {
      // Callback is not r/w or r/o, go to another one in line
      ++i;
      continue;
    }

    bool onCheckThread;
    nsresult rv = mCallbacks[i].OnCheckThread(&onCheckThread);

    if (NS_SUCCEEDED(rv) && !onCheckThread) {
      // Redispatch to the target thread
      rv = mCallbacks[i].mTarget->Dispatch(NewRunnableMethod("net::CacheEntry::InvokeCallbacksLock",
                                                             this,
                                                             &CacheEntry::InvokeCallbacksLock),
                                           nsIEventTarget::DISPATCH_NORMAL);
      if (NS_SUCCEEDED(rv)) {
        LOG(("  re-dispatching to target thread"));
        return false;
      }
    }

    Callback callback = mCallbacks[i];
    mCallbacks.RemoveElementAt(i);

    if (NS_SUCCEEDED(rv) && !InvokeCallback(callback)) {
      // Callback didn't fire, put it back and go to another one in line.
      // Only reason InvokeCallback returns false is that onCacheEntryCheck
      // returns RECHECK_AFTER_WRITE_FINISHED.  If we would stop the loop, other
      // readers or potential writers would be unnecessarily kept from being
      // invoked.
      size_t pos = std::min(mCallbacks.Length(), static_cast<size_t>(i));
      mCallbacks.InsertElementAt(pos, callback);
      ++i;
    }
  }

  if (recreatedHandle) {
    // Must be released outside of the lock, enters InvokeCallback on the new entry
    mozilla::MutexAutoUnlock unlock(mLock);
    recreatedHandle = nullptr;
  }

  return true;
}

bool CacheEntry::InvokeCallback(Callback & aCallback)
{
  LOG(("CacheEntry::InvokeCallback [this=%p, state=%s, cb=%p]",
    this, StateString(mState), aCallback.mCallback.get()));

  mLock.AssertCurrentThreadOwns();

  // When this entry is doomed we want to notify the callback any time
  if (!mIsDoomed) {
    // When we are here, the entry must be loaded from disk
    MOZ_ASSERT(mState > LOADING);

    if (mState == WRITING || mState == REVALIDATING) {
      // Prevent invoking other callbacks since one of them is now writing
      // or revalidating this entry.  No consumers should get this entry
      // until metadata are filled with values downloaded from the server
      // or the entry revalidated and output stream has been opened.
      LOG(("  entry is being written/revalidated, callback bypassed"));
      return false;
    }

    // mRecheckAfterWrite flag already set means the callback has already passed
    // the onCacheEntryCheck call. Until the current write is not finished this
    // callback will be bypassed.
    if (!aCallback.mRecheckAfterWrite) {

      if (!aCallback.mReadOnly) {
        if (mState == EMPTY) {
          // Advance to writing state, we expect to invoke the callback and let
          // it fill content of this entry.  Must set and check the state here
          // to prevent more then one
          mState = WRITING;
          LOG(("  advancing to WRITING state"));
        }

        if (!aCallback.mCallback) {
          // We can be given no callback only in case of recreate, it is ok
          // to advance to WRITING state since the caller of recreate is expected
          // to write this entry now.
          return true;
        }
      }

      if (mState == READY) {
        // Metadata present, validate the entry
        uint32_t checkResult;
        {
          // mayhemer: TODO check and solve any potential races of concurent OnCacheEntryCheck
          mozilla::MutexAutoUnlock unlock(mLock);

          RefPtr<CacheEntryHandle> handle = NewHandle();

          nsresult rv = aCallback.mCallback->OnCacheEntryCheck(
            handle, nullptr, &checkResult);
          LOG(("  OnCacheEntryCheck: rv=0x%08" PRIx32 ", result=%" PRId32,
               static_cast<uint32_t>(rv), static_cast<uint32_t>(checkResult)));

          if (NS_FAILED(rv))
            checkResult = ENTRY_NOT_WANTED;
        }

        aCallback.mRevalidating = checkResult == ENTRY_NEEDS_REVALIDATION;

        switch (checkResult) {
        case ENTRY_WANTED:
          // Nothing more to do here, the consumer is responsible to handle
          // the result of OnCacheEntryCheck it self.
          // Proceed to callback...
          break;

        case RECHECK_AFTER_WRITE_FINISHED:
          LOG(("  consumer will check on the entry again after write is done"));
          // The consumer wants the entry to complete first.
          aCallback.mRecheckAfterWrite = true;
          break;

        case ENTRY_NEEDS_REVALIDATION:
          LOG(("  will be holding callbacks until entry is revalidated"));
          // State is READY now and from that state entry cannot transit to any other
          // state then REVALIDATING for which cocurrency is not an issue.  Potentially
          // no need to lock here.
          mState = REVALIDATING;
          break;

        case ENTRY_NOT_WANTED:
          LOG(("  consumer not interested in the entry"));
          // Do not give this entry to the consumer, it is not interested in us.
          aCallback.mNotWanted = true;
          break;
        }
      }
    }
  }

  if (aCallback.mCallback) {
    if (!mIsDoomed && aCallback.mRecheckAfterWrite) {
      // If we don't have data and the callback wants a complete entry,
      // don't invoke now.
      bool bypass = !mHasData;
      if (!bypass && NS_SUCCEEDED(mFileStatus)) {
        int64_t _unused;
        bypass = !mFile->DataSize(&_unused);
      }

      if (bypass) {
        LOG(("  bypassing, entry data still being written"));
        return false;
      }

      // Entry is complete now, do the check+avail call again
      aCallback.mRecheckAfterWrite = false;
      return InvokeCallback(aCallback);
    }

    mozilla::MutexAutoUnlock unlock(mLock);
    InvokeAvailableCallback(aCallback);
  }

  return true;
}

void CacheEntry::InvokeAvailableCallback(Callback const & aCallback)
{
  LOG(("CacheEntry::InvokeAvailableCallback [this=%p, state=%s, cb=%p, r/o=%d, n/w=%d]",
    this, StateString(mState), aCallback.mCallback.get(), aCallback.mReadOnly, aCallback.mNotWanted));

  nsresult rv;

  uint32_t const state = mState;

  // When we are here, the entry must be loaded from disk
  MOZ_ASSERT(state > LOADING || mIsDoomed);

  bool onAvailThread;
  rv = aCallback.OnAvailThread(&onAvailThread);
  if (NS_FAILED(rv)) {
    LOG(("  target thread dead?"));
    return;
  }

  if (!onAvailThread) {
    // Dispatch to the right thread
    RefPtr<AvailableCallbackRunnable> event =
      new AvailableCallbackRunnable(this, aCallback);

    rv = aCallback.mTarget->Dispatch(event, nsIEventTarget::DISPATCH_NORMAL);
    LOG(("  redispatched, (rv = 0x%08" PRIx32 ")", static_cast<uint32_t>(rv)));
    return;
  }

  if (mIsDoomed || aCallback.mNotWanted) {
    LOG(("  doomed or not wanted, notifying OCEA with NS_ERROR_CACHE_KEY_NOT_FOUND"));
    aCallback.mCallback->OnCacheEntryAvailable(
      nullptr, false, nullptr, NS_ERROR_CACHE_KEY_NOT_FOUND);
    return;
  }

  if (state == READY) {
    LOG(("  ready/has-meta, notifying OCEA with entry and NS_OK"));

    if (!aCallback.mSecret)
    {
      mozilla::MutexAutoLock lock(mLock);
      BackgroundOp(Ops::FRECENCYUPDATE);
    }

    OnFetched(aCallback);

    RefPtr<CacheEntryHandle> handle = NewHandle();
    aCallback.mCallback->OnCacheEntryAvailable(
      handle, false, nullptr, NS_OK);
    return;
  }

  // R/O callbacks may do revalidation, let them fall through
  if (aCallback.mReadOnly && !aCallback.mRevalidating) {
    LOG(("  r/o and not ready, notifying OCEA with NS_ERROR_CACHE_KEY_NOT_FOUND"));
    aCallback.mCallback->OnCacheEntryAvailable(
      nullptr, false, nullptr, NS_ERROR_CACHE_KEY_NOT_FOUND);
    return;
  }

  // This is a new or potentially non-valid entry and needs to be fetched first.
  // The CacheEntryHandle blocks other consumers until the channel
  // either releases the entry or marks metadata as filled or whole entry valid,
  // i.e. until MetaDataReady() or SetValid() on the entry is called respectively.

  // Consumer will be responsible to fill or validate the entry metadata and data.

  OnFetched(aCallback);

  RefPtr<CacheEntryHandle> handle = NewWriteHandle();
  rv = aCallback.mCallback->OnCacheEntryAvailable(
    handle, state == WRITING, nullptr, NS_OK);

  if (NS_FAILED(rv)) {
    LOG(("  writing/revalidating failed (0x%08" PRIx32 ")", static_cast<uint32_t>(rv)));

    // Consumer given a new entry failed to take care of the entry.
    OnHandleClosed(handle);
    return;
  }

  LOG(("  writing/revalidating"));
}

void CacheEntry::OnFetched(Callback const & aCallback)
{
  if (NS_SUCCEEDED(mFileStatus) && !aCallback.mSecret) {
    // Let the last-fetched and fetch-count properties be updated.
    mFile->OnFetched();
  }
}

CacheEntryHandle* CacheEntry::NewHandle()
{
  return new CacheEntryHandle(this);
}

CacheEntryHandle* CacheEntry::NewWriteHandle()
{
  mozilla::MutexAutoLock lock(mLock);

  // Ignore the OPEN_SECRETLY flag on purpose here, which should actually be
  // used only along with OPEN_READONLY, but there is no need to enforce that.
  BackgroundOp(Ops::FRECENCYUPDATE);

  return (mWriter = NewHandle());
}

void CacheEntry::OnHandleClosed(CacheEntryHandle const* aHandle)
{
  LOG(("CacheEntry::OnHandleClosed [this=%p, state=%s, handle=%p]", this, StateString(mState), aHandle));

  mozilla::MutexAutoLock lock(mLock);

  if (IsDoomed() && NS_SUCCEEDED(mFileStatus) &&
      // Note: mHandlesCount is dropped before this method is called
      (mHandlesCount == 0 ||
       (mHandlesCount == 1 && mWriter && mWriter != aHandle))
      ) {
    // This entry is no longer referenced from outside and is doomed.
    // We can do this also when there is just reference from the writer,
    // no one else could ever reach the written data.
    // Tell the file to kill the handle, i.e. bypass any I/O operations
    // on it except removing the file.
    mFile->Kill();
  }

  if (mWriter != aHandle) {
    LOG(("  not the writer"));
    return;
  }

  if (mOutputStream) {
    LOG(("  abandoning phantom output stream"));
    // No one took our internal output stream, so there are no data
    // and output stream has to be open symultaneously with input stream
    // on this entry again.
    mHasData = false;
    // This asynchronously ends up invoking callbacks on this entry
    // through OnOutputClosed() call.
    mOutputStream->Close();
    mOutputStream = nullptr;
  } else {
    // We must always redispatch, otherwise there is a risk of stack
    // overflow.  This code can recurse deeply.  It won't execute sooner
    // than we release mLock.
    BackgroundOp(Ops::CALLBACKS, true);
  }

  mWriter = nullptr;

  if (mState == WRITING) {
    LOG(("  reverting to state EMPTY - write failed"));
    mState = EMPTY;
  }
  else if (mState == REVALIDATING) {
    LOG(("  reverting to state READY - reval failed"));
    mState = READY;
  }

  if (mState == READY && !mHasData) {
    // We may get to this state when following steps happen:
    // 1. a new entry is given to a consumer
    // 2. the consumer calls MetaDataReady(), we transit to READY
    // 3. abandons the entry w/o opening the output stream, mHasData left false
    //
    // In this case any following consumer will get a ready entry (with metadata)
    // but in state like the entry data write was still happening (was in progress)
    // and will indefinitely wait for the entry data or even the entry itself when
    // RECHECK_AFTER_WRITE is returned from onCacheEntryCheck.
    LOG(("  we are in READY state, pretend we have data regardless it"
          " has actully been never touched"));
    mHasData = true;
  }
}

void CacheEntry::OnOutputClosed()
{
  // Called when the file's output stream is closed.  Invoke any callbacks
  // waiting for complete entry.

  mozilla::MutexAutoLock lock(mLock);
  InvokeCallbacks();
}

bool CacheEntry::IsReferenced() const
{
  CacheStorageService::Self()->Lock().AssertCurrentThreadOwns();

  // Increasing this counter from 0 to non-null and this check both happen only
  // under the service lock.
  return mHandlesCount > 0;
}

bool CacheEntry::IsFileDoomed()
{
  if (NS_SUCCEEDED(mFileStatus)) {
    return mFile->IsDoomed();
  }

  return false;
}

uint32_t CacheEntry::GetMetadataMemoryConsumption()
{
  NS_ENSURE_SUCCESS(mFileStatus, 0);

  uint32_t size;
  if (NS_FAILED(mFile->ElementsSize(&size)))
    return 0;

  return size;
}

// nsICacheEntry

nsresult CacheEntry::GetPersistent(bool *aPersistToDisk)
{
  // No need to sync when only reading.
  // When consumer needs to be consistent with state of the memory storage entries
  // table, then let it use GetUseDisk getter that must be called under the service lock.
  *aPersistToDisk = mUseDisk;
  return NS_OK;
}

nsresult CacheEntry::GetKey(nsACString & aKey)
{
  aKey.Assign(mURI);
  return NS_OK;
}

nsresult CacheEntry::GetCacheEntryId(uint64_t *aCacheEntryId)
{
  *aCacheEntryId = mCacheEntryId;
  return NS_OK;
}

nsresult CacheEntry::GetFetchCount(int32_t *aFetchCount)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->GetFetchCount(reinterpret_cast<uint32_t*>(aFetchCount));
}

nsresult CacheEntry::GetLastFetched(uint32_t *aLastFetched)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->GetLastFetched(aLastFetched);
}

nsresult CacheEntry::GetLastModified(uint32_t *aLastModified)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->GetLastModified(aLastModified);
}

nsresult CacheEntry::GetExpirationTime(uint32_t *aExpirationTime)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->GetExpirationTime(aExpirationTime);
}

nsresult CacheEntry::GetOnStartTime(uint64_t *aTime)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);
  return mFile->GetOnStartTime(aTime);
}

nsresult CacheEntry::GetOnStopTime(uint64_t *aTime)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);
  return mFile->GetOnStopTime(aTime);
}

nsresult CacheEntry::SetNetworkTimes(uint64_t aOnStartTime, uint64_t aOnStopTime)
{
  if (NS_SUCCEEDED(mFileStatus)) {
    return mFile->SetNetworkTimes(aOnStartTime, aOnStopTime);
  }
  return NS_ERROR_NOT_AVAILABLE;
}

nsresult CacheEntry::GetIsForcedValid(bool *aIsForcedValid)
{
  NS_ENSURE_ARG(aIsForcedValid);

  MOZ_ASSERT(mState > LOADING);

  if (mPinned) {
    *aIsForcedValid = true;
    return NS_OK;
  }

  nsAutoCString key;
  nsresult rv = HashingKey(key);
  if (NS_FAILED(rv)) {
    return rv;
  }

  *aIsForcedValid = CacheStorageService::Self()->IsForcedValidEntry(mStorageID, key);
  LOG(("CacheEntry::GetIsForcedValid [this=%p, IsForcedValid=%d]", this, *aIsForcedValid));

  return NS_OK;
}

nsresult CacheEntry::ForceValidFor(uint32_t aSecondsToTheFuture)
{
  LOG(("CacheEntry::ForceValidFor [this=%p, aSecondsToTheFuture=%d]", this, aSecondsToTheFuture));

  nsAutoCString key;
  nsresult rv = HashingKey(key);
  if (NS_FAILED(rv)) {
    return rv;
  }

  CacheStorageService::Self()->ForceEntryValidFor(mStorageID, key, aSecondsToTheFuture);

  return NS_OK;
}

nsresult CacheEntry::SetExpirationTime(uint32_t aExpirationTime)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  nsresult rv = mFile->SetExpirationTime(aExpirationTime);
  NS_ENSURE_SUCCESS(rv, rv);

  // Aligned assignment, thus atomic.
  mSortingExpirationTime = aExpirationTime;
  return NS_OK;
}

nsresult CacheEntry::OpenInputStream(int64_t offset, nsIInputStream * *_retval)
{
  LOG(("CacheEntry::OpenInputStream [this=%p]", this));
  return OpenInputStreamInternal(offset, nullptr, _retval);
}

nsresult CacheEntry::OpenAlternativeInputStream(const nsACString & type, nsIInputStream * *_retval)
{
  LOG(("CacheEntry::OpenAlternativeInputStream [this=%p, type=%s]", this,
       PromiseFlatCString(type).get()));
  return OpenInputStreamInternal(0, PromiseFlatCString(type).get(), _retval);
}

nsresult CacheEntry::OpenInputStreamInternal(int64_t offset, const char *aAltDataType, nsIInputStream * *_retval)
{
  LOG(("CacheEntry::OpenInputStreamInternal [this=%p]", this));

  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  nsresult rv;

  RefPtr<CacheEntryHandle> selfHandle = NewHandle();

  nsCOMPtr<nsIInputStream> stream;
  if (aAltDataType) {
    rv = mFile->OpenAlternativeInputStream(selfHandle, aAltDataType,
                                           getter_AddRefs(stream));
    if (NS_FAILED(rv)) {
      // Failure of this method may be legal when the alternative data requested
      // is not avaialble or of a different type.  Console error logs are ensured
      // by CacheFile::OpenAlternativeInputStream.
      return rv;
    }
  } else {
    rv = mFile->OpenInputStream(selfHandle, getter_AddRefs(stream));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  nsCOMPtr<nsISeekableStream> seekable =
    do_QueryInterface(stream, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, offset);
  NS_ENSURE_SUCCESS(rv, rv);

  mozilla::MutexAutoLock lock(mLock);

  if (!mHasData) {
    // So far output stream on this new entry not opened, do it now.
    LOG(("  creating phantom output stream"));
    rv = OpenOutputStreamInternal(0, getter_AddRefs(mOutputStream));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  stream.forget(_retval);
  return NS_OK;
}

nsresult CacheEntry::OpenOutputStream(int64_t offset, int64_t predictedSize, nsIOutputStream * *_retval)
{
  LOG(("CacheEntry::OpenOutputStream [this=%p]", this));

  nsresult rv;

  mozilla::MutexAutoLock lock(mLock);

  MOZ_ASSERT(mState > EMPTY);

  if (mFile->EntryWouldExceedLimit(0, predictedSize, false)) {
    LOG(("  entry would exceed size limit"));
    return NS_ERROR_FILE_TOO_BIG;
  }

  if (mOutputStream && !mIsDoomed) {
    LOG(("  giving phantom output stream"));
    mOutputStream.forget(_retval);
  }
  else {
    rv = OpenOutputStreamInternal(offset, _retval);
    if (NS_FAILED(rv)) return rv;
  }

  // Entry considered ready when writer opens output stream.
  if (mState < READY)
    mState = READY;

  // Invoke any pending readers now.
  InvokeCallbacks();

  return NS_OK;
}

nsresult CacheEntry::OpenAlternativeOutputStream(const nsACString & type, int64_t predictedSize, nsIOutputStream * *_retval)
{
  LOG(("CacheEntry::OpenAlternativeOutputStream [this=%p, type=%s]", this,
       PromiseFlatCString(type).get()));

  nsresult rv;

  mozilla::MutexAutoLock lock(mLock);

  if (!mHasData || mState < READY || mOutputStream || mIsDoomed) {
    LOG(("  entry not in state to write alt-data"));
    return NS_ERROR_NOT_AVAILABLE;
  }

  if (mFile->EntryWouldExceedLimit(0, predictedSize, true)) {
    LOG(("  entry would exceed size limit"));
    return NS_ERROR_FILE_TOO_BIG;
  }

  nsCOMPtr<nsIOutputStream> stream;
  rv = mFile->OpenAlternativeOutputStream(nullptr,
                                          PromiseFlatCString(type).get(),
                                          getter_AddRefs(stream));
  NS_ENSURE_SUCCESS(rv, rv);

  stream.swap(*_retval);
  return NS_OK;
}

nsresult CacheEntry::OpenOutputStreamInternal(int64_t offset, nsIOutputStream * *_retval)
{
  LOG(("CacheEntry::OpenOutputStreamInternal [this=%p]", this));

  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  mLock.AssertCurrentThreadOwns();

  if (mIsDoomed) {
    LOG(("  doomed..."));
    return NS_ERROR_NOT_AVAILABLE;
  }

  MOZ_ASSERT(mState > LOADING);

  nsresult rv;

  // No need to sync on mUseDisk here, we don't need to be consistent
  // with content of the memory storage entries hash table.
  if (!mUseDisk) {
    rv = mFile->SetMemoryOnly();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  RefPtr<CacheOutputCloseListener> listener =
    new CacheOutputCloseListener(this);

  nsCOMPtr<nsIOutputStream> stream;
  rv = mFile->OpenOutputStream(listener, getter_AddRefs(stream));
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsISeekableStream> seekable =
    do_QueryInterface(stream, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, offset);
  NS_ENSURE_SUCCESS(rv, rv);

  // Prevent opening output stream again.
  mHasData = true;

  stream.swap(*_retval);
  return NS_OK;
}

nsresult CacheEntry::GetSecurityInfo(nsISupports * *aSecurityInfo)
{
  {
    mozilla::MutexAutoLock lock(mLock);
    if (mSecurityInfoLoaded) {
      NS_IF_ADDREF(*aSecurityInfo = mSecurityInfo);
      return NS_OK;
    }
  }

  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  nsCString info;
  nsCOMPtr<nsISupports> secInfo;
  nsresult rv;

  rv = mFile->GetElement("security-info", getter_Copies(info));
  NS_ENSURE_SUCCESS(rv, rv);

  if (!info.IsVoid()) {
    rv = NS_DeserializeObject(info, getter_AddRefs(secInfo));
    NS_ENSURE_SUCCESS(rv, rv);
  }

  {
    mozilla::MutexAutoLock lock(mLock);

    mSecurityInfo.swap(secInfo);
    mSecurityInfoLoaded = true;

    NS_IF_ADDREF(*aSecurityInfo = mSecurityInfo);
  }

  return NS_OK;
}
nsresult CacheEntry::SetSecurityInfo(nsISupports *aSecurityInfo)
{
  nsresult rv;

  NS_ENSURE_SUCCESS(mFileStatus, mFileStatus);

  {
    mozilla::MutexAutoLock lock(mLock);

    mSecurityInfo = aSecurityInfo;
    mSecurityInfoLoaded = true;
  }

  nsCOMPtr<nsISerializable> serializable =
    do_QueryInterface(aSecurityInfo);
  if (aSecurityInfo && !serializable)
    return NS_ERROR_UNEXPECTED;

  nsCString info;
  if (serializable) {
    rv = NS_SerializeToString(serializable, info);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  rv = mFile->SetElement("security-info", info.Length() ? info.get() : nullptr);
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}

nsresult CacheEntry::GetStorageDataSize(uint32_t *aStorageDataSize)
{
  NS_ENSURE_ARG(aStorageDataSize);

  int64_t dataSize;
  nsresult rv = GetDataSize(&dataSize);
  if (NS_FAILED(rv))
    return rv;

  *aStorageDataSize = (uint32_t)std::min(int64_t(uint32_t(-1)), dataSize);

  return NS_OK;
}

nsresult CacheEntry::AsyncDoom(nsICacheEntryDoomCallback *aCallback)
{
  LOG(("CacheEntry::AsyncDoom [this=%p]", this));

  {
    mozilla::MutexAutoLock lock(mLock);

    if (mIsDoomed || mDoomCallback)
      return NS_ERROR_IN_PROGRESS; // to aggregate have DOOMING state

    RemoveForcedValidity();

    mIsDoomed = true;
    mDoomCallback = aCallback;
  }

  // This immediately removes the entry from the master hashtable and also
  // immediately dooms the file.  This way we make sure that any consumer
  // after this point asking for the same entry won't get
  //   a) this entry
  //   b) a new entry with the same file
  PurgeAndDoom();

  return NS_OK;
}

nsresult CacheEntry::GetMetaDataElement(const char * aKey, char * *aRetval)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->GetElement(aKey, aRetval);
}

nsresult CacheEntry::SetMetaDataElement(const char * aKey, const char * aValue)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->SetElement(aKey, aValue);
}

nsresult CacheEntry::VisitMetaData(nsICacheEntryMetaDataVisitor *aVisitor)
{
  NS_ENSURE_SUCCESS(mFileStatus, NS_ERROR_NOT_AVAILABLE);

  return mFile->VisitMetaData(aVisitor);
}

nsresult CacheEntry::MetaDataReady()
{
  mozilla::MutexAutoLock lock(mLock);

  LOG(("CacheEntry::MetaDataReady [this=%p, state=%s]", this, StateString(mState)));

  MOZ_ASSERT(mState > EMPTY);

  if (mState == WRITING)
    mState = READY;

  InvokeCallbacks();

  return NS_OK;
}

nsresult CacheEntry::SetValid()
{
  LOG(("CacheEntry::SetValid [this=%p, state=%s]", this, StateString(mState)));

  nsCOMPtr<nsIOutputStream> outputStream;

  {
    mozilla::MutexAutoLock lock(mLock);

    MOZ_ASSERT(mState > EMPTY);

    mState = READY;
    mHasData = true;

    InvokeCallbacks();

    outputStream.swap(mOutputStream);
  }

  if (outputStream) {
    LOG(("  abandoning phantom output stream"));
    outputStream->Close();
  }

  return NS_OK;
}

nsresult CacheEntry::Recreate(bool aMemoryOnly,
                                   nsICacheEntry **_retval)
{
  LOG(("CacheEntry::Recreate [this=%p, state=%s]", this, StateString(mState)));

  mozilla::MutexAutoLock lock(mLock);

  RefPtr<CacheEntryHandle> handle = ReopenTruncated(aMemoryOnly, nullptr);
  if (handle) {
    handle.forget(_retval);
    return NS_OK;
  }

  BackgroundOp(Ops::CALLBACKS, true);
  return NS_ERROR_NOT_AVAILABLE;
}

nsresult CacheEntry::GetDataSize(int64_t *aDataSize)
{
  LOG(("CacheEntry::GetDataSize [this=%p]", this));
  *aDataSize = 0;

  {
    mozilla::MutexAutoLock lock(mLock);

    if (!mHasData) {
      LOG(("  write in progress (no data)"));
      return NS_ERROR_IN_PROGRESS;
    }
  }

  NS_ENSURE_SUCCESS(mFileStatus, mFileStatus);

  // mayhemer: TODO Problem with compression?
  if (!mFile->DataSize(aDataSize)) {
    LOG(("  write in progress (stream active)"));
    return NS_ERROR_IN_PROGRESS;
  }

  LOG(("  size=%" PRId64, *aDataSize));
  return NS_OK;
}


nsresult CacheEntry::GetAltDataSize(int64_t *aDataSize)
{
  LOG(("CacheEntry::GetAltDataSize [this=%p]", this));
  if (NS_FAILED(mFileStatus)) {
    return mFileStatus;
  }
  return mFile->GetAltDataSize(aDataSize);
}


nsresult CacheEntry::MarkValid()
{
  // NOT IMPLEMENTED ACTUALLY
  return NS_OK;
}

nsresult CacheEntry::MaybeMarkValid()
{
  // NOT IMPLEMENTED ACTUALLY
  return NS_OK;
}

nsresult CacheEntry::HasWriteAccess(bool aWriteAllowed, bool *aWriteAccess)
{
  *aWriteAccess = aWriteAllowed;
  return NS_OK;
}

nsresult CacheEntry::Close()
{
  // NOT IMPLEMENTED ACTUALLY
  return NS_OK;
}

nsresult CacheEntry::GetDiskStorageSizeInKB(uint32_t *aDiskStorageSize)
{
  if (NS_FAILED(mFileStatus)) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  return mFile->GetDiskStorageSizeInKB(aDiskStorageSize);
}

nsresult CacheEntry::GetLoadContextInfo(nsILoadContextInfo** aInfo)
{
  nsCOMPtr<nsILoadContextInfo> info = CacheFileUtils::ParseKey(mStorageID);
  if (!info) {
    return NS_ERROR_FAILURE;
  }

  info.forget(aInfo);

  return NS_OK;
}

// nsIRunnable

NS_IMETHODIMP CacheEntry::Run()
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());

  mozilla::MutexAutoLock lock(mLock);

  BackgroundOp(mBackgroundOperations.Grab());
  return NS_OK;
}

// Management methods

double CacheEntry::GetFrecency() const
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());
  return mFrecency;
}

uint32_t CacheEntry::GetExpirationTime() const
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());
  return mSortingExpirationTime;
}

bool CacheEntry::IsRegistered() const
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());
  return mRegistration == REGISTERED;
}

bool CacheEntry::CanRegister() const
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());
  return mRegistration == NEVERREGISTERED;
}

void CacheEntry::SetRegistered(bool aRegistered)
{
  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());

  if (aRegistered) {
    MOZ_ASSERT(mRegistration == NEVERREGISTERED);
    mRegistration = REGISTERED;
  }
  else {
    MOZ_ASSERT(mRegistration == REGISTERED);
    mRegistration = DEREGISTERED;
  }
}

bool CacheEntry::DeferOrBypassRemovalOnPinStatus(bool aPinned)
{
  LOG(("CacheEntry::DeferOrBypassRemovalOnPinStatus [this=%p]", this));

  mozilla::MutexAutoLock lock(mLock);

  if (mPinningKnown) {
    LOG(("  pinned=%d, caller=%d", mPinned, aPinned));
    // Bypass when the pin status of this entry doesn't match the pin status
    // caller wants to remove
    return mPinned != aPinned;
  }

  LOG(("  pinning unknown, caller=%d", aPinned));
  // Oterwise, remember to doom after the status is determined for any
  // callback opening the entry after this point...
  Callback c(this, aPinned);
  RememberCallback(c);
  // ...and always bypass
  return true;
}

bool CacheEntry::Purge(uint32_t aWhat)
{
  LOG(("CacheEntry::Purge [this=%p, what=%d]", this, aWhat));

  MOZ_ASSERT(CacheStorageService::IsOnManagementThread());

  switch (aWhat) {
  case PURGE_DATA_ONLY_DISK_BACKED:
  case PURGE_WHOLE_ONLY_DISK_BACKED:
    // This is an in-memory only entry, don't purge it
    if (!mUseDisk) {
      LOG(("  not using disk"));
      return false;
    }
  }

  if (mState == WRITING || mState == LOADING || mFrecency == 0) {
    // In-progress (write or load) entries should (at least for consistency and from
    // the logical point of view) stay in memory.
    // Zero-frecency entries are those which have never been given to any consumer, those
    // are actually very fresh and should not go just because frecency had not been set
    // so far.
    LOG(("  state=%s, frecency=%1.10f", StateString(mState), mFrecency));
    return false;
  }

  if (NS_SUCCEEDED(mFileStatus) && mFile->IsWriteInProgress()) {
    // The file is used when there are open streams or chunks/metadata still waiting for
    // write.  In this case, this entry cannot be purged, otherwise reopenned entry
    // would may not even find the data on disk - CacheFile is not shared and cannot be
    // left orphan when its job is not done, hence keep the whole entry.
    LOG(("  file still under use"));
    return false;
  }

  switch (aWhat) {
  case PURGE_WHOLE_ONLY_DISK_BACKED:
  case PURGE_WHOLE:
    {
      if (!CacheStorageService::Self()->RemoveEntry(this, true)) {
        LOG(("  not purging, still referenced"));
        return false;
      }

      CacheStorageService::Self()->UnregisterEntry(this);

      // Entry removed it self from control arrays, return true
      return true;
    }

  case PURGE_DATA_ONLY_DISK_BACKED:
    {
      NS_ENSURE_SUCCESS(mFileStatus, false);

      mFile->ThrowMemoryCachedData();

      // Entry has been left in control arrays, return false (not purged)
      return false;
    }
  }

  LOG(("  ?"));
  return false;
}

void CacheEntry::PurgeAndDoom()
{
  LOG(("CacheEntry::PurgeAndDoom [this=%p]", this));

  CacheStorageService::Self()->RemoveEntry(this);
  DoomAlreadyRemoved();
}

void CacheEntry::DoomAlreadyRemoved()
{
  LOG(("CacheEntry::DoomAlreadyRemoved [this=%p]", this));

  mozilla::MutexAutoLock lock(mLock);

  RemoveForcedValidity();

  mIsDoomed = true;

  // Pretend pinning is know.  This entry is now doomed for good, so don't
  // bother with defering doom because of unknown pinning state any more.
  mPinningKnown = true;

  // This schedules dooming of the file, dooming is ensured to happen
  // sooner than demand to open the same file made after this point
  // so that we don't get this file for any newer opened entry(s).
  DoomFile();

  // Must force post here since may be indirectly called from
  // InvokeCallbacks of this entry and we don't want reentrancy here.
  BackgroundOp(Ops::CALLBACKS, true);
  // Process immediately when on the management thread.
  BackgroundOp(Ops::UNREGISTER);
}

void CacheEntry::DoomFile()
{
  nsresult rv = NS_ERROR_NOT_AVAILABLE;

  if (NS_SUCCEEDED(mFileStatus)) {
    if (mHandlesCount == 0 ||
        (mHandlesCount == 1 && mWriter)) {
      // We kill the file also when there is just reference from the writer,
      // no one else could ever reach the written data.  Obvisouly also
      // when there is no reference at all (should we ever end up here
      // in that case.)
      // Tell the file to kill the handle, i.e. bypass any I/O operations
      // on it except removing the file.
      mFile->Kill();
    }

    // Always calls the callback asynchronously.
    rv = mFile->Doom(mDoomCallback ? this : nullptr);
    if (NS_SUCCEEDED(rv)) {
      LOG(("  file doomed"));
      return;
    }

    if (NS_ERROR_FILE_NOT_FOUND == rv) {
      // File is set to be just memory-only, notify the callbacks
      // and pretend dooming has succeeded.  From point of view of
      // the entry it actually did - the data is gone and cannot be
      // reused.
      rv = NS_OK;
    }
  }

  // Always posts to the main thread.
  OnFileDoomed(rv);
}

void CacheEntry::RemoveForcedValidity()
{
  mLock.AssertCurrentThreadOwns();

  nsresult rv;

  if (mIsDoomed) {
    return;
  }

  nsAutoCString entryKey;
  rv = HashingKey(entryKey);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return;
  }

  CacheStorageService::Self()->RemoveEntryForceValid(mStorageID, entryKey);
}

void CacheEntry::BackgroundOp(uint32_t aOperations, bool aForceAsync)
{
  mLock.AssertCurrentThreadOwns();

  if (!CacheStorageService::IsOnManagementThread() || aForceAsync) {
    if (mBackgroundOperations.Set(aOperations))
      CacheStorageService::Self()->Dispatch(this);

    LOG(("CacheEntry::BackgroundOp this=%p dipatch of %x", this, aOperations));
    return;
  }

  {
    mozilla::MutexAutoUnlock unlock(mLock);

    MOZ_ASSERT(CacheStorageService::IsOnManagementThread());

    if (aOperations & Ops::FRECENCYUPDATE) {
      ++mUseCount;

      #ifndef M_LN2
      #define M_LN2 0.69314718055994530942
      #endif

      // Half-life is dynamic, in seconds.
      static double half_life = CacheObserver::HalfLifeSeconds();
      // Must convert from seconds to milliseconds since PR_Now() gives usecs.
      static double const decay = (M_LN2 / half_life) / static_cast<double>(PR_USEC_PER_SEC);

      double now_decay = static_cast<double>(PR_Now()) * decay;

      if (mFrecency == 0) {
        mFrecency = now_decay;
      }
      else {
        // TODO: when C++11 enabled, use std::log1p(n) which is equal to log(n + 1) but
        // more precise.
        mFrecency = log(exp(mFrecency - now_decay) + 1) + now_decay;
      }
      LOG(("CacheEntry FRECENCYUPDATE [this=%p, frecency=%1.10f]", this, mFrecency));

      // Because CacheFile::Set*() are not thread-safe to use (uses WeakReference that
      // is not thread-safe) we must post to the main thread...
      NS_DispatchToMainThread(
        NewRunnableMethod<double>("net::CacheEntry::StoreFrecency",
                                  this,
                                  &CacheEntry::StoreFrecency,
                                  mFrecency));
    }

    if (aOperations & Ops::REGISTER) {
      LOG(("CacheEntry REGISTER [this=%p]", this));

      CacheStorageService::Self()->RegisterEntry(this);
    }

    if (aOperations & Ops::UNREGISTER) {
      LOG(("CacheEntry UNREGISTER [this=%p]", this));

      CacheStorageService::Self()->UnregisterEntry(this);
    }
  } // unlock

  if (aOperations & Ops::CALLBACKS) {
    LOG(("CacheEntry CALLBACKS (invoke) [this=%p]", this));

    InvokeCallbacks();
  }
}

void CacheEntry::StoreFrecency(double aFrecency)
{
  MOZ_ASSERT(NS_IsMainThread());

  if (NS_SUCCEEDED(mFileStatus)) {
    mFile->SetFrecency(FRECENCY2INT(aFrecency));
  }
}

// CacheOutputCloseListener

CacheOutputCloseListener::CacheOutputCloseListener(CacheEntry* aEntry)
  : Runnable("net::CacheOutputCloseListener")
  , mEntry(aEntry)
{
}

void CacheOutputCloseListener::OnOutputClosed()
{
  // We need this class and to redispatch since this callback is invoked
  // under the file's lock and to do the job we need to enter the entry's
  // lock too.  That would lead to potential deadlocks.
  NS_DispatchToCurrentThread(this);
}

NS_IMETHODIMP CacheOutputCloseListener::Run()
{
  mEntry->OnOutputClosed();
  return NS_OK;
}

// Memory reporting

size_t CacheEntry::SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
  size_t n = 0;

  n += mCallbacks.ShallowSizeOfExcludingThis(mallocSizeOf);
  if (mFile) {
    n += mFile->SizeOfIncludingThis(mallocSizeOf);
  }

  n += mURI.SizeOfExcludingThisIfUnshared(mallocSizeOf);
  n += mEnhanceID.SizeOfExcludingThisIfUnshared(mallocSizeOf);
  n += mStorageID.SizeOfExcludingThisIfUnshared(mallocSizeOf);

  // mDoomCallback is an arbitrary class that is probably reported elsewhere.
  // mOutputStream is reported in mFile.
  // mWriter is one of many handles we create, but (intentionally) not keep
  // any reference to, so those unfortunately cannot be reported.  Handles are
  // small, though.
  // mSecurityInfo doesn't impl nsISizeOf.

  return n;
}

size_t CacheEntry::SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
  return mallocSizeOf(this) + SizeOfExcludingThis(mallocSizeOf);
}

} // namespace net
} // namespace mozilla

Coverage Report

Created: 2018-09-25 14:53