1 files changed, 147 insertions, 0 deletions
diff --git a/js/src/vm/SharedImmutableStringsCache.cpp b/js/src/vm/SharedImmutableStringsCache.cpp
new file mode 100644
index 0000000000..4428121400
--- /dev/null
+++ b/js/src/vm/SharedImmutableStringsCache.cpp
@@ -0,0 +1,147 @@
+/* -*- 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