1 files changed, 79 insertions, 0 deletions
diff --git a/dom/quota/ScopedLogExtraInfo.cpp b/dom/quota/ScopedLogExtraInfo.cpp
new file mode 100644
index 0000000000..e9ddf84a8d
--- /dev/null
+++ b/dom/quota/ScopedLogExtraInfo.cpp
@@ -0,0 +1,79 @@
+/* -*- 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 "ScopedLogExtraInfo.h"
+
+namespace mozilla::dom::quota {
+
+#ifdef QM_SCOPED_LOG_EXTRA_INFO_ENABLED
+MOZ_THREAD_LOCAL(const nsACString*) ScopedLogExtraInfo::sQueryValue;
+MOZ_THREAD_LOCAL(const nsACString*) ScopedLogExtraInfo::sContextValue;
+
+/* static */
+auto ScopedLogExtraInfo::FindSlot(const char* aTag) {
+  // XXX For now, don't use a real map but just allow the known tag values.
+
+  if (aTag == kTagQuery) {
+    return &sQueryValue;
+  }
+
+  if (aTag == kTagContext) {
+    return &sContextValue;
+  }
+
+  MOZ_CRASH("Unknown tag!");
+}
+
+ScopedLogExtraInfo::~ScopedLogExtraInfo() {
+  if (mTag) {
+    MOZ_ASSERT(&mCurrentValue == FindSlot(mTag)->get(),
+               "Bad scoping of ScopedLogExtraInfo, must not be interleaved!");
+
+    FindSlot(mTag)->set(mPreviousValue);
+  }
+}
+
+ScopedLogExtraInfo::ScopedLogExtraInfo(ScopedLogExtraInfo&& aOther) noexcept
+    : mTag(aOther.mTag),
+      mPreviousValue(aOther.mPreviousValue),
+      mCurrentValue(std::move(aOther.mCurrentValue)) {
+  aOther.mTag = nullptr;
+  FindSlot(mTag)->set(&mCurrentValue);
+}
+
+/* static */ ScopedLogExtraInfo::ScopedLogExtraInfoMap
+ScopedLogExtraInfo::GetExtraInfoMap() {
+  // This could be done in a cheaper way, but this is never called on a hot
+  // path, so we anticipate using a real map inside here to make use simpler for
+  // the caller(s).
+
+  ScopedLogExtraInfoMap map;
+  if (sQueryValue.get()) {
+    map.emplace(kTagQuery, sQueryValue.get());
+  }
+
+  if (sContextValue.get()) {
+    map.emplace(kTagContext, sContextValue.get());
+  }
+
+  return map;
+}
+
+/* static */ void ScopedLogExtraInfo::Initialize() {
+  MOZ_ALWAYS_TRUE(sQueryValue.init());
+  MOZ_ALWAYS_TRUE(sContextValue.init());
+}
+
+void ScopedLogExtraInfo::AddInfo() {
+  auto* slot = FindSlot(mTag);
+  MOZ_ASSERT(slot);
+  mPreviousValue = slot->get();
+
+  slot->set(&mCurrentValue);
+}
+#endif
+
+}  // namespace mozilla::dom::quota