Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 886 insertions, 0 deletions

diff --git a/mozglue/baseprofiler/public/BaseProfilerMarkersPrerequisites.h b/mozglue/baseprofiler/public/BaseProfilerMarkersPrerequisites.h
new file mode 100644
index 0000000000..15fd729d0c
--- /dev/null
+++ b/mozglue/baseprofiler/public/BaseProfilerMarkersPrerequisites.h
@@ -0,0 +1,886 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+// This header contains basic definitions required to create marker types, and
+// to add markers to the profiler buffers.
+//
+// In most cases, #include "mozilla/BaseProfilerMarkers.h" instead, or
+// #include "mozilla/BaseProfilerMarkerTypes.h" for common marker types.
+
+#ifndef BaseProfilerMarkersPrerequisites_h
+#define BaseProfilerMarkersPrerequisites_h
+
+namespace mozilla {
+
+enum class StackCaptureOptions {
+  NoStack,    // No stack captured.
+  Full,       // Capture a full stack, including label frames, JS frames and
+              // native frames.
+  NonNative,  // Capture a stack without native frames for reduced overhead.
+};
+
+}
+
+#include "BaseProfilingCategory.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ProfileChunkedBuffer.h"
+#include "mozilla/BaseProfilerState.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Variant.h"
+
+#include <initializer_list>
+#include <string_view>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+namespace mozilla {
+
+// Return a NotNull<const CHAR*> pointing at the literal empty string `""`.
+template <typename CHAR>
+constexpr const CHAR* LiteralEmptyStringPointer() {
+  static_assert(std::is_same_v<CHAR, char> || std::is_same_v<CHAR, char16_t>,
+                "Only char and char16_t are supported in Firefox");
+  if constexpr (std::is_same_v<CHAR, char>) {
+    return "";
+  }
+  if constexpr (std::is_same_v<CHAR, char16_t>) {
+    return u"";
+  }
+}
+
+// Return a string_view<CHAR> pointing at the literal empty string.
+template <typename CHAR>
+constexpr std::basic_string_view<CHAR> LiteralEmptyStringView() {
+  static_assert(std::is_same_v<CHAR, char> || std::is_same_v<CHAR, char16_t>,
+                "Only char and char16_t are supported in Firefox");
+  // Use `operator""sv()` from <string_view>.
+  using namespace std::literals::string_view_literals;
+  if constexpr (std::is_same_v<CHAR, char>) {
+    return ""sv;
+  }
+  if constexpr (std::is_same_v<CHAR, char16_t>) {
+    return u""sv;
+  }
+}
+
+// General string view, optimized for short on-stack life before serialization,
+// and between deserialization and JSON-streaming.
+template <typename CHAR>
+class MOZ_STACK_CLASS ProfilerStringView {
+ public:
+  // Default constructor points at "" (literal empty string).
+  constexpr ProfilerStringView() = default;
+
+  // Don't allow copy.
+  ProfilerStringView(const ProfilerStringView&) = delete;
+  ProfilerStringView& operator=(const ProfilerStringView&) = delete;
+
+  // Allow move. For consistency the moved-from string is always reset to "".
+  constexpr ProfilerStringView(ProfilerStringView&& aOther)
+      : mStringView(std::move(aOther.mStringView)),
+        mOwnership(aOther.mOwnership) {
+    if (mOwnership == Ownership::OwnedThroughStringView) {
+      // We now own the buffer, make the other point at the literal "".
+      aOther.mStringView = LiteralEmptyStringView<CHAR>();
+      aOther.mOwnership = Ownership::Literal;
+    }
+  }
+  constexpr ProfilerStringView& operator=(ProfilerStringView&& aOther) {
+    mStringView = std::move(aOther.mStringView);
+    mOwnership = aOther.mOwnership;
+    if (mOwnership == Ownership::OwnedThroughStringView) {
+      // We now own the buffer, make the other point at the literal "".
+      aOther.mStringView = LiteralEmptyStringView<CHAR>();
+      aOther.mOwnership = Ownership::Literal;
+    }
+    return *this;
+  }
+
+  ~ProfilerStringView() {
+    if (MOZ_UNLIKELY(mOwnership == Ownership::OwnedThroughStringView)) {
+      // We own the buffer pointed at by mStringView, destroy it.
+      // This is only used between deserialization and streaming.
+      delete mStringView.data();
+    }
+  }
+
+  // Implicit construction from nullptr, points at "" (literal empty string).
+  constexpr MOZ_IMPLICIT ProfilerStringView(decltype(nullptr)) {}
+
+  // Implicit constructor from a literal string.
+  template <size_t Np1>
+  constexpr MOZ_IMPLICIT ProfilerStringView(const CHAR (&aLiteralString)[Np1])
+      : ProfilerStringView(aLiteralString, Np1 - 1, Ownership::Literal) {}
+
+  // Constructor from a non-literal string.
+  constexpr ProfilerStringView(const CHAR* aString, size_t aLength)
+      : ProfilerStringView(aString, aLength, Ownership::Reference) {}
+
+  // Implicit constructor from a string_view.
+  constexpr MOZ_IMPLICIT ProfilerStringView(
+      const std::basic_string_view<CHAR>& aStringView)
+      : ProfilerStringView(aStringView.data(), aStringView.length(),
+                           Ownership::Reference) {}
+
+  // Implicit constructor from an expiring string_view. We assume that the
+  // pointed-at string will outlive this ProfilerStringView.
+  constexpr MOZ_IMPLICIT ProfilerStringView(
+      std::basic_string_view<CHAR>&& aStringView)
+      : ProfilerStringView(aStringView.data(), aStringView.length(),
+                           Ownership::Reference) {}
+
+  // Implicit constructor from std::string.
+  constexpr MOZ_IMPLICIT ProfilerStringView(
+      const std::basic_string<CHAR>& aString)
+      : ProfilerStringView(aString.data(), aString.length(),
+                           Ownership::Reference) {}
+
+  // Construction from a raw pointer to a null-terminated string.
+  // This is a named class-static function to make it more obvious where work is
+  // being done (to determine the string length), and encourage users to instead
+  // provide a length, if already known.
+  // TODO: Find callers and convert them to constructor instead if possible.
+  static constexpr ProfilerStringView WrapNullTerminatedString(
+      const CHAR* aString) {
+    return ProfilerStringView(
+        aString, aString ? std::char_traits<CHAR>::length(aString) : 0,
+        Ownership::Reference);
+  }
+
+  // Implicit constructor for an object with member functions `Data()`
+  // `Length()`, and `IsLiteral()`, common in xpcom strings.
+  template <
+      typename String,
+      typename DataReturnType = decltype(std::declval<const String>().Data()),
+      typename LengthReturnType =
+          decltype(std::declval<const String>().Length()),
+      typename IsLiteralReturnType =
+          decltype(std::declval<const String>().IsLiteral()),
+      typename =
+          std::enable_if_t<std::is_convertible_v<DataReturnType, const CHAR*> &&
+                           std::is_integral_v<LengthReturnType> &&
+                           std::is_same_v<IsLiteralReturnType, bool>>>
+  constexpr MOZ_IMPLICIT ProfilerStringView(const String& aString)
+      : ProfilerStringView(
+            static_cast<const CHAR*>(aString.Data()), aString.Length(),
+            aString.IsLiteral() ? Ownership::Literal : Ownership::Reference) {}
+
+  [[nodiscard]] constexpr const std::basic_string_view<CHAR>& StringView()
+      const {
+    return mStringView;
+  }
+
+  [[nodiscard]] constexpr size_t Length() const { return mStringView.length(); }
+
+  [[nodiscard]] constexpr bool IsLiteral() const {
+    return mOwnership == Ownership::Literal;
+  }
+  [[nodiscard]] constexpr bool IsReference() const {
+    return mOwnership == Ownership::Reference;
+  }
+  // No `IsOwned...()` because it's a secret, only used internally!
+
+  [[nodiscard]] Span<const CHAR> AsSpan() const {
+    return Span<const CHAR>(mStringView.data(), mStringView.length());
+  }
+  [[nodiscard]] operator Span<const CHAR>() const { return AsSpan(); }
+
+ private:
+  enum class Ownership { Literal, Reference, OwnedThroughStringView };
+
+  // Allow deserializer to store anything here.
+  friend ProfileBufferEntryReader::Deserializer<ProfilerStringView>;
+
+  constexpr ProfilerStringView(const CHAR* aString, size_t aLength,
+                               Ownership aOwnership)
+      : mStringView(aString ? std::basic_string_view<CHAR>(aString, aLength)
+                            : LiteralEmptyStringView<CHAR>()),
+        mOwnership(aString ? aOwnership : Ownership::Literal) {}
+
+  // String view to an outside string (literal or reference).
+  // We may actually own the pointed-at buffer, but it is only used internally
+  // between deserialization and JSON streaming.
+  std::basic_string_view<CHAR> mStringView = LiteralEmptyStringView<CHAR>();
+
+  Ownership mOwnership = Ownership::Literal;
+};
+
+using ProfilerString8View = ProfilerStringView<char>;
+using ProfilerString16View = ProfilerStringView<char16_t>;
+
+// This compulsory marker parameter contains the required category information.
+class MarkerCategory {
+ public:
+  // Constructor from category pair (includes both super- and sub-categories).
+  constexpr explicit MarkerCategory(
+      baseprofiler::ProfilingCategoryPair aCategoryPair)
+      : mCategoryPair(aCategoryPair) {}
+
+  // Returns the stored category pair.
+  constexpr baseprofiler::ProfilingCategoryPair CategoryPair() const {
+    return mCategoryPair;
+  }
+
+  // Returns the super-category from the stored category pair.
+  baseprofiler::ProfilingCategory GetCategory() const {
+    return GetProfilingCategoryPairInfo(mCategoryPair).mCategory;
+  }
+
+ private:
+  baseprofiler::ProfilingCategoryPair mCategoryPair =
+      baseprofiler::ProfilingCategoryPair::OTHER;
+};
+
+namespace baseprofiler::category {
+
+// Each category pair name constructs a MarkerCategory.
+// E.g.: mozilla::baseprofiler::category::OTHER_Profiling
+// Profiler macros will take the category name alone without namespace.
+// E.g.: `PROFILER_MARKER_UNTYPED("name", OTHER_Profiling)`
+#define CATEGORY_ENUM_BEGIN_CATEGORY(name, labelAsString, color)
+#define CATEGORY_ENUM_SUBCATEGORY(supercategory, name, labelAsString) \
+  static constexpr MarkerCategory name{ProfilingCategoryPair::name};
+#define CATEGORY_ENUM_END_CATEGORY
+MOZ_PROFILING_CATEGORY_LIST(CATEGORY_ENUM_BEGIN_CATEGORY,
+                            CATEGORY_ENUM_SUBCATEGORY,
+                            CATEGORY_ENUM_END_CATEGORY)
+#undef CATEGORY_ENUM_BEGIN_CATEGORY
+#undef CATEGORY_ENUM_SUBCATEGORY
+#undef CATEGORY_ENUM_END_CATEGORY
+
+// Import `MarkerCategory` into this namespace. This will allow using this type
+// dynamically in macros that prepend `::mozilla::baseprofiler::category::` to
+// the given category, e.g.:
+// `PROFILER_MARKER_UNTYPED("name", MarkerCategory(...))`
+using MarkerCategory = ::mozilla::MarkerCategory;
+
+}  // namespace baseprofiler::category
+
+// The classes below are all embedded in a `MarkerOptions` object.
+class MarkerOptions;
+
+// This marker option captures a given thread id.
+// If left unspecified (by default construction) during the add-marker call, the
+// current thread id will be used then.
+class MarkerThreadId {
+ public:
+  // Default constructor, keeps the thread id unspecified.
+  constexpr MarkerThreadId() = default;
+
+  // Constructor from a given thread id.
+  constexpr explicit MarkerThreadId(
+      baseprofiler::BaseProfilerThreadId aThreadId)
+      : mThreadId(aThreadId) {}
+
+  // Use the current thread's id.
+  static MarkerThreadId CurrentThread() {
+    return MarkerThreadId(baseprofiler::profiler_current_thread_id());
+  }
+
+  // Use the main thread's id. This can be useful to record a marker from a
+  // possibly-unregistered thread, and display it in the main thread track.
+  static MarkerThreadId MainThread() {
+    return MarkerThreadId(baseprofiler::profiler_main_thread_id());
+  }
+
+  [[nodiscard]] constexpr baseprofiler::BaseProfilerThreadId ThreadId() const {
+    return mThreadId;
+  }
+
+  [[nodiscard]] constexpr bool IsUnspecified() const {
+    return !mThreadId.IsSpecified();
+  }
+
+ private:
+  baseprofiler::BaseProfilerThreadId mThreadId;
+};
+
+// This marker option contains marker timing information.
+// This class encapsulates the logic for correctly storing a marker based on its
+// Use the static methods to create the MarkerTiming. This is a transient object
+// that is being used to enforce the constraints of the combinations of the
+// data.
+class MarkerTiming {
+ public:
+  // The following static methods are used to create the MarkerTiming based on
+  // the type that it is.
+
+  static MarkerTiming InstantAt(const TimeStamp& aTime) {
+    MOZ_ASSERT(!aTime.IsNull(), "Time is null for an instant marker.");
+    return MarkerTiming{aTime, TimeStamp{}, MarkerTiming::Phase::Instant};
+  }
+
+  static MarkerTiming InstantNow() { return InstantAt(TimeStamp::Now()); }
+
+  static MarkerTiming Interval(const TimeStamp& aStartTime,
+                               const TimeStamp& aEndTime) {
+    MOZ_ASSERT(!aStartTime.IsNull(),
+               "Start time is null for an interval marker.");
+    MOZ_ASSERT(!aEndTime.IsNull(), "End time is null for an interval marker.");
+    return MarkerTiming{aStartTime, aEndTime, MarkerTiming::Phase::Interval};
+  }
+
+  static MarkerTiming IntervalUntilNowFrom(const TimeStamp& aStartTime) {
+    return Interval(aStartTime, TimeStamp::Now());
+  }
+
+  static MarkerTiming IntervalStart(const TimeStamp& aTime = TimeStamp::Now()) {
+    MOZ_ASSERT(!aTime.IsNull(), "Time is null for an interval start marker.");
+    return MarkerTiming{aTime, TimeStamp{}, MarkerTiming::Phase::IntervalStart};
+  }
+
+  static MarkerTiming IntervalEnd(const TimeStamp& aTime = TimeStamp::Now()) {
+    MOZ_ASSERT(!aTime.IsNull(), "Time is null for an interval end marker.");
+    return MarkerTiming{TimeStamp{}, aTime, MarkerTiming::Phase::IntervalEnd};
+  }
+
+  // Set the interval end in this timing.
+  // If there was already a start time, this makes it a full interval.
+  void SetIntervalEnd(const TimeStamp& aTime = TimeStamp::Now()) {
+    MOZ_ASSERT(!aTime.IsNull(), "Time is null for an interval end marker.");
+    mEndTime = aTime;
+    mPhase = mStartTime.IsNull() ? Phase::IntervalEnd : Phase::Interval;
+  }
+
+  [[nodiscard]] const TimeStamp& StartTime() const { return mStartTime; }
+  [[nodiscard]] const TimeStamp& EndTime() const { return mEndTime; }
+
+  enum class Phase : uint8_t {
+    Instant = 0,
+    Interval = 1,
+    IntervalStart = 2,
+    IntervalEnd = 3,
+  };
+
+  [[nodiscard]] Phase MarkerPhase() const {
+    MOZ_ASSERT(!IsUnspecified());
+    return mPhase;
+  }
+
+  // The following getter methods are used to put the value into the buffer for
+  // storage.
+  [[nodiscard]] double GetStartTime() const {
+    MOZ_ASSERT(!IsUnspecified());
+    // If mStartTime is null (e.g., for IntervalEnd), this will output 0.0 as
+    // expected.
+    return MarkerTiming::timeStampToDouble(mStartTime);
+  }
+
+  [[nodiscard]] double GetEndTime() const {
+    MOZ_ASSERT(!IsUnspecified());
+    // If mEndTime is null (e.g., for Instant or IntervalStart), this will
+    // output 0.0 as expected.
+    return MarkerTiming::timeStampToDouble(mEndTime);
+  }
+
+  [[nodiscard]] uint8_t GetPhase() const {
+    MOZ_ASSERT(!IsUnspecified());
+    return static_cast<uint8_t>(mPhase);
+  }
+
+  // This is a constructor for Rust FFI bindings. It must not be used outside of
+  // this! Please see the other static constructors above.
+  static void UnsafeConstruct(MarkerTiming* aMarkerTiming,
+                              const TimeStamp& aStartTime,
+                              const TimeStamp& aEndTime, Phase aPhase) {
+    new (aMarkerTiming) MarkerTiming{aStartTime, aEndTime, aPhase};
+  }
+
+ private:
+  friend ProfileBufferEntryWriter::Serializer<MarkerTiming>;
+  friend ProfileBufferEntryReader::Deserializer<MarkerTiming>;
+  friend MarkerOptions;
+
+  // Default timing leaves it internally "unspecified", serialization getters
+  // and add-marker functions will default to `InstantNow()`.
+  constexpr MarkerTiming() = default;
+
+  // This should only be used by internal profiler code.
+  [[nodiscard]] bool IsUnspecified() const {
+    return mStartTime.IsNull() && mEndTime.IsNull();
+  }
+
+  // Full constructor, used by static factory functions.
+  constexpr MarkerTiming(const TimeStamp& aStartTime, const TimeStamp& aEndTime,
+                         Phase aPhase)
+      : mStartTime(aStartTime), mEndTime(aEndTime), mPhase(aPhase) {}
+
+  static double timeStampToDouble(const TimeStamp& time) {
+    if (time.IsNull()) {
+      // The Phase lets us know not to use this value.
+      return 0;
+    }
+    return (time - TimeStamp::ProcessCreation()).ToMilliseconds();
+  }
+
+  TimeStamp mStartTime;
+  TimeStamp mEndTime;
+  Phase mPhase = Phase::Instant;
+};
+
+// This marker option allows three cases:
+// - By default, no stacks are captured.
+// - The caller can request a stack capture, and the add-marker code will take
+//   care of it in the most efficient way.
+// - The caller can still provide an existing backtrace, for cases where a
+//   marker reports something that happened elsewhere.
+class MarkerStack {
+ public:
+  // Default constructor, no capture.
+  constexpr MarkerStack() = default;
+
+  // Disallow copy.
+  MarkerStack(const MarkerStack&) = delete;
+  MarkerStack& operator=(const MarkerStack&) = delete;
+
+  // Allow move.
+  MarkerStack(MarkerStack&& aOther)
+      : mCaptureOptions(aOther.mCaptureOptions),
+        mOptionalChunkedBufferStorage(
+            std::move(aOther.mOptionalChunkedBufferStorage)),
+        mChunkedBuffer(aOther.mChunkedBuffer) {
+    AssertInvariants();
+    aOther.Clear();
+  }
+  MarkerStack& operator=(MarkerStack&& aOther) {
+    mCaptureOptions = aOther.mCaptureOptions;
+    mOptionalChunkedBufferStorage =
+        std::move(aOther.mOptionalChunkedBufferStorage);
+    mChunkedBuffer = aOther.mChunkedBuffer;
+    AssertInvariants();
+    aOther.Clear();
+    return *this;
+  }
+
+  // Take ownership of a backtrace. If null or empty, equivalent to NoStack().
+  explicit MarkerStack(UniquePtr<ProfileChunkedBuffer>&& aExternalChunkedBuffer)
+      : mOptionalChunkedBufferStorage(
+            (!aExternalChunkedBuffer || aExternalChunkedBuffer->IsEmpty())
+                ? nullptr
+                : std::move(aExternalChunkedBuffer)),
+        mChunkedBuffer(mOptionalChunkedBufferStorage.get()) {
+    AssertInvariants();
+  }
+
+  // Use an existing backtrace stored elsewhere, which the user must guarantee
+  // is alive during the add-marker call. If empty, equivalent to NoStack().
+  explicit MarkerStack(ProfileChunkedBuffer& aExternalChunkedBuffer)
+      : mChunkedBuffer(aExternalChunkedBuffer.IsEmpty()
+                           ? nullptr
+                           : &aExternalChunkedBuffer) {
+    AssertInvariants();
+  }
+
+  // Don't capture a stack in this marker.
+  static MarkerStack NoStack() {
+    return MarkerStack(StackCaptureOptions::NoStack);
+  }
+
+  // Capture a stack when adding this marker.
+  static MarkerStack Capture(
+      StackCaptureOptions aCaptureOptions = StackCaptureOptions::Full) {
+    // Actual capture will be handled inside profiler_add_marker.
+    return MarkerStack(aCaptureOptions);
+  }
+
+  // Optionally capture a stack, useful for avoiding long-winded ternaries.
+  static MarkerStack MaybeCapture(bool aDoCapture) {
+    return aDoCapture ? Capture() : NoStack();
+  }
+
+  // Use an existing backtrace stored elsewhere, which the user must guarantee
+  // is alive during the add-marker call. If empty, equivalent to NoStack().
+  static MarkerStack UseBacktrace(
+      ProfileChunkedBuffer& aExternalChunkedBuffer) {
+    return MarkerStack(aExternalChunkedBuffer);
+  }
+
+  // Take ownership of a backtrace previously captured with
+  // `profiler_capture_backtrace()`. If null, equivalent to NoStack().
+  static MarkerStack TakeBacktrace(
+      UniquePtr<ProfileChunkedBuffer>&& aExternalChunkedBuffer) {
+    return MarkerStack(std::move(aExternalChunkedBuffer));
+  }
+
+  // Construct with the given capture options.
+  static MarkerStack WithCaptureOptions(StackCaptureOptions aCaptureOptions) {
+    return MarkerStack(aCaptureOptions);
+  }
+
+  [[nodiscard]] StackCaptureOptions CaptureOptions() const {
+    return mCaptureOptions;
+  }
+
+  ProfileChunkedBuffer* GetChunkedBuffer() const { return mChunkedBuffer; }
+
+  // Use backtrace after a request. If null, equivalent to NoStack().
+  void UseRequestedBacktrace(ProfileChunkedBuffer* aExternalChunkedBuffer) {
+    MOZ_RELEASE_ASSERT(mCaptureOptions != StackCaptureOptions::NoStack);
+    mCaptureOptions = StackCaptureOptions::NoStack;
+    if (aExternalChunkedBuffer && !aExternalChunkedBuffer->IsEmpty()) {
+      // We only need to use the provided buffer if it is not empty.
+      mChunkedBuffer = aExternalChunkedBuffer;
+    }
+    AssertInvariants();
+  }
+
+  void Clear() {
+    mCaptureOptions = StackCaptureOptions::NoStack;
+    mOptionalChunkedBufferStorage.reset();
+    mChunkedBuffer = nullptr;
+    AssertInvariants();
+  }
+
+ private:
+  explicit MarkerStack(StackCaptureOptions aCaptureOptions)
+      : mCaptureOptions(aCaptureOptions) {
+    AssertInvariants();
+  }
+
+  // This should be called after every constructor and non-const function.
+  void AssertInvariants() const {
+#ifdef DEBUG
+    if (mCaptureOptions != StackCaptureOptions::NoStack) {
+      MOZ_ASSERT(!mOptionalChunkedBufferStorage,
+                 "We should not hold a buffer when capture is requested");
+      MOZ_ASSERT(!mChunkedBuffer,
+                 "We should not point at a buffer when capture is requested");
+    } else {
+      if (mOptionalChunkedBufferStorage) {
+        MOZ_ASSERT(mChunkedBuffer == mOptionalChunkedBufferStorage.get(),
+                   "Non-null mOptionalChunkedBufferStorage must be pointed-at "
+                   "by mChunkedBuffer");
+      }
+      if (mChunkedBuffer) {
+        MOZ_ASSERT(!mChunkedBuffer->IsEmpty(),
+                   "Non-null mChunkedBuffer must not be empty");
+      }
+    }
+#endif  // DEBUG
+  }
+
+  StackCaptureOptions mCaptureOptions = StackCaptureOptions::NoStack;
+
+  // Optional storage for the backtrace, in case it was captured before the
+  // add-marker call.
+  UniquePtr<ProfileChunkedBuffer> mOptionalChunkedBufferStorage;
+
+  // If not null, this points to the backtrace. It may point to a backtrace
+  // temporarily stored on the stack, or to mOptionalChunkedBufferStorage.
+  ProfileChunkedBuffer* mChunkedBuffer = nullptr;
+};
+
+// This marker option captures a given inner window id.
+class MarkerInnerWindowId {
+ public:
+  // Default constructor, it leaves the id unspecified.
+  constexpr MarkerInnerWindowId() = default;
+
+  // Constructor with a specified inner window id.
+  constexpr explicit MarkerInnerWindowId(uint64_t i) : mInnerWindowId(i) {}
+
+  // Constructor with either specified inner window id or Nothing.
+  constexpr explicit MarkerInnerWindowId(const Maybe<uint64_t>& i)
+      : mInnerWindowId(i.valueOr(scNoId)) {}
+
+  // Explicit option with unspecified id.
+  constexpr static MarkerInnerWindowId NoId() { return MarkerInnerWindowId{}; }
+
+  [[nodiscard]] bool IsUnspecified() const { return mInnerWindowId == scNoId; }
+
+  [[nodiscard]] constexpr uint64_t Id() const { return mInnerWindowId; }
+
+ private:
+  static constexpr uint64_t scNoId = 0;
+  uint64_t mInnerWindowId = scNoId;
+};
+
+// This class combines each of the possible marker options above.
+class MarkerOptions {
+ public:
+  // Constructor from individual options (including none).
+  // Implicit to allow `{}` and one option type as-is.
+  // Options that are not provided here are defaulted. In particular, timing
+  // defaults to `MarkerTiming::InstantNow()` when the marker is recorded.
+  template <typename... Options>
+  MOZ_IMPLICIT MarkerOptions(Options&&... aOptions) {
+    (Set(std::forward<Options>(aOptions)), ...);
+  }
+
+  // Disallow copy.
+  MarkerOptions(const MarkerOptions&) = delete;
+  MarkerOptions& operator=(const MarkerOptions&) = delete;
+
+  // Allow move.
+  MarkerOptions(MarkerOptions&&) = default;
+  MarkerOptions& operator=(MarkerOptions&&) = default;
+
+  // The embedded `MarkerTiming` hasn't been specified yet.
+  [[nodiscard]] bool IsTimingUnspecified() const {
+    return mTiming.IsUnspecified();
+  }
+
+  // Each option may be added in a chain by e.g.:
+  // `options.Set(MarkerThreadId(123)).Set(MarkerTiming::IntervalEnd())`.
+  // When passed to an add-marker function, it must be an rvalue, either created
+  // on the spot, or `std::move`d from storage, e.g.:
+  // `PROFILER_MARKER_UNTYPED("...", std::move(options).Set(...))`;
+  //
+  // Options can be read by their name (without "Marker"), e.g.: `o.ThreadId()`.
+  // Add "Ref" for a non-const reference, e.g.: `o.ThreadIdRef() = ...;`
+#define FUNCTIONS_ON_MEMBER(NAME)                      \
+  MarkerOptions& Set(Marker##NAME&& a##NAME)& {        \
+    m##NAME = std::move(a##NAME);                      \
+    return *this;                                      \
+  }                                                    \
+                                                       \
+  MarkerOptions&& Set(Marker##NAME&& a##NAME)&& {      \
+    m##NAME = std::move(a##NAME);                      \
+    return std::move(*this);                           \
+  }                                                    \
+                                                       \
+  const Marker##NAME& NAME() const { return m##NAME; } \
+                                                       \
+  Marker##NAME& NAME##Ref() { return m##NAME; }
+
+  FUNCTIONS_ON_MEMBER(ThreadId);
+  FUNCTIONS_ON_MEMBER(Timing);
+  FUNCTIONS_ON_MEMBER(Stack);
+  FUNCTIONS_ON_MEMBER(InnerWindowId);
+#undef FUNCTIONS_ON_MEMBER
+
+ private:
+  friend ProfileBufferEntryReader::Deserializer<MarkerOptions>;
+
+  MarkerThreadId mThreadId;
+  MarkerTiming mTiming;
+  MarkerStack mStack;
+  MarkerInnerWindowId mInnerWindowId;
+};
+
+}  // namespace mozilla
+
+namespace mozilla::baseprofiler::markers {
+
+// Default marker payload types, with no extra information, not even a marker
+// type and payload. This is intended for label-only markers.
+struct NoPayload final {};
+
+}  // namespace mozilla::baseprofiler::markers
+
+namespace mozilla {
+
+class JSONWriter;
+
+// This class collects all the information necessary to stream the JSON schema
+// that informs the front-end how to display a type of markers.
+// It will be created and populated in `MarkerTypeDisplay()` functions in each
+// marker type definition, see Add/Set functions.
+class MarkerSchema {
+ public:
+  enum class Location : unsigned {
+    MarkerChart,
+    MarkerTable,
+    // This adds markers to the main marker timeline in the header.
+    TimelineOverview,
+    // In the timeline, this is a section that breaks out markers that are
+    // related to memory. When memory counters are enabled, this is its own
+    // track, otherwise it is displayed with the main thread.
+    TimelineMemory,
+    // This adds markers to the IPC timeline area in the header.
+    TimelineIPC,
+    // This adds markers to the FileIO timeline area in the header.
+    TimelineFileIO,
+    // TODO - This is not supported yet.
+    StackChart
+  };
+
+  // Used as constructor parameter, to explicitly specify that the location (and
+  // other display options) are handled as a special case in the front-end.
+  // In this case, *no* schema will be output for this type.
+  struct SpecialFrontendLocation {};
+
+  enum class Format {
+    // ----------------------------------------------------
+    // String types.
+
+    // Show the URL, and handle PII sanitization
+    Url,
+    // Show the file path, and handle PII sanitization.
+    FilePath,
+    // Important, do not put URL or file path information here, as it will not
+    // be sanitized. Please be careful with including other types of PII here as
+    // well.
+    // e.g. "Label: Some String"
+    String,
+
+    // ----------------------------------------------------
+    // Numeric types
+
+    // For time data that represents a duration of time.
+    // e.g. "Label: 5s, 5ms, 5μs"
+    Duration,
+    // Data that happened at a specific time, relative to the start of the
+    // profile. e.g. "Label: 15.5s, 20.5ms, 30.5μs"
+    Time,
+    // The following are alternatives to display a time only in a specific unit
+    // of time.
+    Seconds,       // "Label: 5s"
+    Milliseconds,  // "Label: 5ms"
+    Microseconds,  // "Label: 5μs"
+    Nanoseconds,   // "Label: 5ns"
+    // e.g. "Label: 5.55mb, 5 bytes, 312.5kb"
+    Bytes,
+    // This should be a value between 0 and 1.
+    // "Label: 50%"
+    Percentage,
+    // The integer should be used for generic representations of numbers.
+    // Do not use it for time information.
+    // "Label: 52, 5,323, 1,234,567"
+    Integer,
+    // The decimal should be used for generic representations of numbers.
+    // Do not use it for time information.
+    // "Label: 52.23, 0.0054, 123,456.78"
+    Decimal
+  };
+
+  enum class Searchable { NotSearchable, Searchable };
+
+  // Marker schema, with a non-empty list of locations where markers should be
+  // shown.
+  // Tech note: Even though `aLocations` are templated arguments, they are
+  // assigned to an `enum class` object, so they can only be of that enum type.
+  template <typename... Locations>
+  explicit MarkerSchema(Location aLocation, Locations... aLocations)
+      : mLocations{aLocation, aLocations...} {}
+
+  // Alternative constructor for MarkerSchema.
+  explicit MarkerSchema(const mozilla::MarkerSchema::Location* aLocations,
+                        size_t aLength)
+      : mLocations(aLocations, aLocations + aLength) {}
+
+  // Marker schema for types that have special frontend handling.
+  // Nothing else should be set in this case.
+  // Implicit to allow quick return from MarkerTypeDisplay functions.
+  MOZ_IMPLICIT MarkerSchema(SpecialFrontendLocation) {}
+
+  // Caller must specify location(s) or SpecialFrontendLocation above.
+  MarkerSchema() = delete;
+
+  // Optional labels in the marker chart, the chart tooltip, and the marker
+  // table. If not provided, the marker "name" will be used. The given string
+  // can contain element keys in braces to include data elements streamed by
+  // `StreamJSONMarkerData()`. E.g.: "This is {text}"
+
+#define LABEL_SETTER(name)                       \
+  MarkerSchema& Set##name(std::string a##name) { \
+    m##name = std::move(a##name);                \
+    return *this;                                \
+  }
+
+  LABEL_SETTER(ChartLabel)
+  LABEL_SETTER(TooltipLabel)
+  LABEL_SETTER(TableLabel)
+
+#undef LABEL_SETTER
+
+  MarkerSchema& SetAllLabels(std::string aText) {
+    // Here we set the same text in each label.
+    // TODO: Move to a single "label" field once the front-end allows it.
+    SetChartLabel(aText);
+    SetTooltipLabel(aText);
+    SetTableLabel(std::move(aText));
+    return *this;
+  }
+
+  // Each data element that is streamed by `StreamJSONMarkerData()` can be
+  // displayed as indicated by using one of the `Add...` function below.
+  // Each `Add...` will add a line in the full marker description. Parameters:
+  // - `aKey`: Element property name as streamed by `StreamJSONMarkerData()`.
+  // - `aLabel`: Optional prefix. Defaults to the key name.
+  // - `aFormat`: How to format the data element value, see `Format` above.
+  // - `aSearchable`: Optional, indicates if the value is used in searches,
+  //   defaults to false.
+
+  MarkerSchema& AddKeyFormat(std::string aKey, Format aFormat) {
+    mData.emplace_back(mozilla::VariantType<DynamicData>{},
+                       DynamicData{std::move(aKey), mozilla::Nothing{}, aFormat,
+                                   mozilla::Nothing{}});
+    return *this;
+  }
+
+  MarkerSchema& AddKeyLabelFormat(std::string aKey, std::string aLabel,
+                                  Format aFormat) {
+    mData.emplace_back(
+        mozilla::VariantType<DynamicData>{},
+        DynamicData{std::move(aKey), mozilla::Some(std::move(aLabel)), aFormat,
+                    mozilla::Nothing{}});
+    return *this;
+  }
+
+  MarkerSchema& AddKeyFormatSearchable(std::string aKey, Format aFormat,
+                                       Searchable aSearchable) {
+    mData.emplace_back(mozilla::VariantType<DynamicData>{},
+                       DynamicData{std::move(aKey), mozilla::Nothing{}, aFormat,
+                                   mozilla::Some(aSearchable)});
+    return *this;
+  }
+
+  MarkerSchema& AddKeyLabelFormatSearchable(std::string aKey,
+                                            std::string aLabel, Format aFormat,
+                                            Searchable aSearchable) {
+    mData.emplace_back(
+        mozilla::VariantType<DynamicData>{},
+        DynamicData{std::move(aKey), mozilla::Some(std::move(aLabel)), aFormat,
+                    mozilla::Some(aSearchable)});
+    return *this;
+  }
+
+  // The display may also include static rows.
+
+  MarkerSchema& AddStaticLabelValue(std::string aLabel, std::string aValue) {
+    mData.emplace_back(mozilla::VariantType<StaticData>{},
+                       StaticData{std::move(aLabel), std::move(aValue)});
+    return *this;
+  }
+
+  // Internal streaming function.
+  MFBT_API void Stream(JSONWriter& aWriter, const Span<const char>& aName) &&;
+
+ private:
+  MFBT_API static Span<const char> LocationToStringSpan(Location aLocation);
+  MFBT_API static Span<const char> FormatToStringSpan(Format aFormat);
+
+  // List of marker display locations. Empty for SpecialFrontendLocation.
+  std::vector<Location> mLocations;
+  // Labels for different places.
+  std::string mChartLabel;
+  std::string mTooltipLabel;
+  std::string mTableLabel;
+  // Main display, made of zero or more rows of key+label+format or label+value.
+ private:
+  struct DynamicData {
+    std::string mKey;
+    mozilla::Maybe<std::string> mLabel;
+    Format mFormat;
+    mozilla::Maybe<Searchable> mSearchable;
+  };
+  struct StaticData {
+    std::string mLabel;
+    std::string mValue;
+  };
+  using DataRow = mozilla::Variant<DynamicData, StaticData>;
+  using DataRowVector = std::vector<DataRow>;
+
+  DataRowVector mData;
+};
+
+}  // namespace mozilla
+
+#endif  // BaseProfilerMarkersPrerequisites_h