Quelle SharedPrefMap.cpp Sprache: C

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 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 "SharedPrefMap.h"

#include "mozilla/dom/ipc/MemMapSnapshot.h"

#include "mozilla/BinarySearch.h"
#include "mozilla/ResultExtensions.h"
#include "mozilla/Try.h"
#include "mozilla/ipc/FileDescriptor.h"

namespace mozilla {

using namespace ipc;

static inline size_t GetAlignmentOffset(size_t aOffset, size_t aAlign) {
  auto mod = aOffset % aAlign;
  return mod ? aAlign - mod : 0;
}

SharedPrefMap::SharedPrefMap(const SharedMemoryHandle& aMapHandle,
                             size_t aMapSize) {
  auto map = MakeRefPtr<SharedMemory>();
  {
    auto result = map->SetHandle(SharedMemory::CloneHandle(aMapHandle),
                                 SharedMemory::OpenRights::RightsReadOnly);
    MOZ_RELEASE_ASSERT(result);
  }
  {
    auto result = map->Map(aMapSize);
    MOZ_RELEASE_ASSERT(result);
  }

  // We return literal nsCStrings pointing to the mapped data for preference
  // names and string values, which means that we may still have references to
  // the mapped data even after this instance is destroyed. That means that we
  // need to keep the mapping alive until process shutdown, in order to be safe.
  mMappedMemory = map->TakeMapping();
  mHandle = map->TakeHandle();
}

SharedPrefMap::SharedPrefMap(SharedPrefMapBuilder&& aBuilder) {
  RefPtr<SharedMemory> map;
  auto result = aBuilder.Finalize(map);
  MOZ_RELEASE_ASSERT(result.isOk() && map);

  mMappedMemory = map->TakeMapping();
  mHandle = map->TakeHandle();
}

mozilla::ipc::SharedMemoryHandle SharedPrefMap::CloneHandle() const {
  return SharedMemory::CloneHandle(mHandle);
}

bool SharedPrefMap::Has(const char* aKey) const {
  size_t index;
  return Find(aKey, &index);
}

Maybe<const SharedPrefMap::Pref> SharedPrefMap::Get(const char* aKey) const {
  Maybe<const Pref> result;

  size_t index;
  if (Find(aKey, &index)) {
    result.emplace(Pref{this, &Entries()[index]});
  }

  return result;
}

bool SharedPrefMap::Find(const char* aKey, size_t* aIndex) const {
  const auto& keys = KeyTable();

  return BinarySearchIf(
      Entries(), 0, EntryCount(),
      [&](const Entry& aEntry) {
        return strcmp(aKey, keys.GetBare(aEntry.mKey));
      },
      aIndex);
}

void SharedPrefMapBuilder::Add(const nsCString& aKey, const Flags& aFlags,
                               bool aDefaultValue, bool aUserValue) {
  mEntries.AppendElement(Entry{
      aKey.get(),
      mKeyTable.Add(aKey),
      {aDefaultValue, aUserValue},
      uint8_t(PrefType::Bool),
      aFlags.mHasDefaultValue,
      aFlags.mHasUserValue,
      aFlags.mIsSticky,
      aFlags.mIsLocked,
      aFlags.mIsSanitized,
      aFlags.mIsSkippedByIteration,
  });
}

void SharedPrefMapBuilder::Add(const nsCString& aKey, const Flags& aFlags,
                               int32_t aDefaultValue, int32_t aUserValue) {
  ValueIdx index;
  if (aFlags.mHasUserValue) {
    index = mIntValueTable.Add(aDefaultValue, aUserValue);
  } else {
    index = mIntValueTable.Add(aDefaultValue);
  }

  mEntries.AppendElement(Entry{
      aKey.get(),
      mKeyTable.Add(aKey),
      {index},
      uint8_t(PrefType::Int),
      aFlags.mHasDefaultValue,
      aFlags.mHasUserValue,
      aFlags.mIsSticky,
      aFlags.mIsLocked,
      aFlags.mIsSanitized,
      aFlags.mIsSkippedByIteration,
  });
}

void SharedPrefMapBuilder::Add(const nsCString& aKey, const Flags& aFlags,
                               const nsCString& aDefaultValue,
                               const nsCString& aUserValue) {
  ValueIdx index;
  StringTableEntry defaultVal = mValueStringTable.Add(aDefaultValue);
  if (aFlags.mHasUserValue) {
    StringTableEntry userVal = mValueStringTable.Add(aUserValue);
    index = mStringValueTable.Add(defaultVal, userVal);
  } else {
    index = mStringValueTable.Add(defaultVal);
  }

  mEntries.AppendElement(Entry{
      aKey.get(),
      mKeyTable.Add(aKey),
      {index},
      uint8_t(PrefType::String),
      aFlags.mHasDefaultValue,
      aFlags.mHasUserValue,
      aFlags.mIsSticky,
      aFlags.mIsLocked,
      aFlags.mIsSanitized,
      aFlags.mIsSkippedByIteration,
  });
}

Result<Ok, nsresult> SharedPrefMapBuilder::Finalize(
    RefPtr<SharedMemory>& aMap) {
  using Header = SharedPrefMap::Header;

  // Create an array of entry pointers for the entry array, and sort it by
  // preference name prior to serialization, so that entries can be looked up
  // using binary search.
  nsTArray<Entry*> entries(mEntries.Length());
  for (auto& entry : mEntries) {
    entries.AppendElement(&entry);
  }
  entries.Sort([](const Entry* aA, const Entry* aB) {
    return strcmp(aA->mKeyString, aB->mKeyString);
  });

  Header header = {uint32_t(entries.Length())};

  size_t offset = sizeof(header);
  offset += GetAlignmentOffset(offset, alignof(Header));

  offset += entries.Length() * sizeof(SharedPrefMap::Entry);

  header.mKeyStrings.mOffset = offset;
  header.mKeyStrings.mSize = mKeyTable.Size();
  offset += header.mKeyStrings.mSize;

  offset += GetAlignmentOffset(offset, mIntValueTable.Alignment());
  header.mUserIntValues.mOffset = offset;
  header.mUserIntValues.mSize = mIntValueTable.UserSize();
  offset += header.mUserIntValues.mSize;

  offset += GetAlignmentOffset(offset, mIntValueTable.Alignment());
  header.mDefaultIntValues.mOffset = offset;
  header.mDefaultIntValues.mSize = mIntValueTable.DefaultSize();
  offset += header.mDefaultIntValues.mSize;

  offset += GetAlignmentOffset(offset, mStringValueTable.Alignment());
  header.mUserStringValues.mOffset = offset;
  header.mUserStringValues.mSize = mStringValueTable.UserSize();
  offset += header.mUserStringValues.mSize;

  offset += GetAlignmentOffset(offset, mStringValueTable.Alignment());
  header.mDefaultStringValues.mOffset = offset;
  header.mDefaultStringValues.mSize = mStringValueTable.DefaultSize();
  offset += header.mDefaultStringValues.mSize;

  header.mValueStrings.mOffset = offset;
  header.mValueStrings.mSize = mValueStringTable.Size();
  offset += header.mValueStrings.mSize;

  MemMapSnapshot mem;
  MOZ_TRY(mem.Init(offset));

  auto headerPtr = mem.Get<Header>();
  headerPtr[0] = header;

  auto* entryPtr = reinterpret_cast<SharedPrefMap::Entry*>(&headerPtr[1]);
  for (auto* entry : entries) {
    *entryPtr = {
        entry->mKey,
        GetValue(*entry),
        entry->mType,
        entry->mHasDefaultValue,
        entry->mHasUserValue,
        entry->mIsSticky,
        entry->mIsLocked,
        entry->mIsSanitized,
        entry->mIsSkippedByIteration,
    };
    entryPtr++;
  }

  auto ptr = mem.Get<uint8_t>();

  mKeyTable.Write({&ptr[header.mKeyStrings.mOffset], header.mKeyStrings.mSize});

  mValueStringTable.Write(
      {&ptr[header.mValueStrings.mOffset], header.mValueStrings.mSize});

  mIntValueTable.WriteDefaultValues(
      {&ptr[header.mDefaultIntValues.mOffset], header.mDefaultIntValues.mSize});
  mIntValueTable.WriteUserValues(
      {&ptr[header.mUserIntValues.mOffset], header.mUserIntValues.mSize});

  mStringValueTable.WriteDefaultValues(
      {&ptr[header.mDefaultStringValues.mOffset],
       header.mDefaultStringValues.mSize});
  mStringValueTable.WriteUserValues(
      {&ptr[header.mUserStringValues.mOffset], header.mUserStringValues.mSize});

  mKeyTable.Clear();
  mValueStringTable.Clear();
  mIntValueTable.Clear();
  mStringValueTable.Clear();
  mEntries.Clear();

  return mem.Finalize(aMap);
}

}  // namespace mozilla

quality95%

¤ Dauer der Verarbeitung: 0.1 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.