Quelle  SharedImmutableStringsCache.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 "vm/SharedImmutableStringsCache-inl.h"

#include "util/Text.h"
#include "vm/MutexIDs.h"  // js::mutexid
#include "vm/Runtime.h"   // JSRuntime

namespace js {

/* static */
SharedImmutableStringsCache SharedImmutableStringsCache::singleton_;

SharedImmutableString::SharedImmutableString(
    SharedImmutableStringsCache::StringBox* box)
    : box_(box) {
  MOZ_ASSERT(box);
  box->refcount++;
}

SharedImmutableString::SharedImmutableString(SharedImmutableString&& rhs)
    : box_(rhs.box_) {
  MOZ_ASSERT(this != &rhs, "self move not allowed");

  MOZ_ASSERT_IF(rhs.box_, rhs.box_->refcount > 0);

  rhs.box_ = nullptr;
}

SharedImmutableString& SharedImmutableString::operator=(
    SharedImmutableString&& rhs) {
  this->~SharedImmutableString();
  new (this) SharedImmutableString(std::move(rhs));
  return *this;
}

SharedImmutableTwoByteString::SharedImmutableTwoByteString(
    SharedImmutableString&& string)
    : string_(std::move(string)) {}

SharedImmutableTwoByteString::SharedImmutableTwoByteString(
    SharedImmutableStringsCache::StringBox* box)
    : string_(box) {
  MOZ_ASSERT(box->length() % sizeof(char16_t) == 0);
}

SharedImmutableTwoByteString::SharedImmutableTwoByteString(
    SharedImmutableTwoByteString&& rhs)
    : string_(std::move(rhs.string_)) {
  MOZ_ASSERT(this != &rhs, "self move not allowed");
}

SharedImmutableTwoByteString& SharedImmutableTwoByteString::operator=(
    SharedImmutableTwoByteString&& rhs) {
  this->~SharedImmutableTwoByteString();
  new (this) SharedImmutableTwoByteString(std::move(rhs));
  return *this;
}

SharedImmutableString::~SharedImmutableString() {
  if (!box_) {
    return;
  }

  auto locked = box_->cache_->lock();

  MOZ_ASSERT(box_->refcount > 0);

  box_->refcount--;
  if (box_->refcount == 0) {
    box_->chars_.reset(nullptr);
  }
}

SharedImmutableString SharedImmutableString::clone() const {
  auto locked = box_->cache_->lock();
  MOZ_ASSERT(box_);
  MOZ_ASSERT(box_->refcount > 0);
  return SharedImmutableString(box_);
}

SharedImmutableTwoByteString SharedImmutableTwoByteString::clone() const {
  return SharedImmutableTwoByteString(string_.clone());
}

[[nodiscard]] SharedImmutableString SharedImmutableStringsCache::getOrCreate(
    OwnedChars&& chars, size_t length) {
  OwnedChars owned(std::move(chars));
  MOZ_ASSERT(owned);
  return getOrCreate(owned.get(), length, [&]() { return std::move(owned); });
}

[[nodiscard]] SharedImmutableString SharedImmutableStringsCache::getOrCreate(
    const char* chars, size_t length) {
  return getOrCreate(chars, length,
                     [&]() { return DuplicateString(chars, length); });
}

bool SharedImmutableStringsCache::init() {
  MOZ_ASSERT(!inner_);

  auto* inner =
      js_new<ExclusiveData<Inner>>(mutexid::SharedImmutableStringsCache);
  if (!inner) {
    return false;
  }

  auto locked = inner->lock();
  inner_ = locked.parent();

  return true;
}

void SharedImmutableStringsCache::free() {
  if (inner_) {
    js_delete(inner_);
    inner_ = nullptr;
  }
}

bool SharedImmutableStringsCache::initSingleton() { return singleton_.init(); }

void SharedImmutableStringsCache::freeSingleton() {
  if (!JSRuntime::hasLiveRuntimes()) {
    singleton_.free();
  }
}

[[nodiscard]] SharedImmutableTwoByteString
SharedImmutableStringsCache::getOrCreate(OwnedTwoByteChars&& chars,
                                         size_t length) {
  OwnedTwoByteChars owned(std::move(chars));
  MOZ_ASSERT(owned);
  return getOrCreate(owned.get(), length, [&]() { return std::move(owned); });
}

[[nodiscard]] SharedImmutableTwoByteString
SharedImmutableStringsCache::getOrCreate(const char16_t* chars, size_t length) {
  return getOrCreate(chars, length,
                     [&]() { return DuplicateString(chars, length); });
}

}  // namespace js