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/* -*- 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 */
#include "ProfileBuffer.h"
#include "mozilla/ProfileBufferEntrySerialization.h"
#include "mozilla/UniquePtrExtensions.h"
#include <string>
class ProfileBuffer;
class ProfilerCodeAddressService;
class ThreadInfo;
class UniqueStacks;
namespace mozilla {
class ProfileChunkedBuffer;
class TimeStamp;
namespace baseprofiler {
class SpliceableJSONWriter;
} // namespace baseprofiler
} // namespace mozilla
// ProfilerBacktrace encapsulates a synchronous sample.
// It can work with a ProfileBuffer and/or a ProfileChunkedBuffer (if both, they
// must already be linked together). The ProfileChunkedBuffer contains all the
// data; the ProfileBuffer is not strictly needed, only provide it if it is
// already available at the call site.
// And these buffers can either be:
// - owned here, so that the ProfilerBacktrace object can be kept for later
// use), OR
// - referenced through pointers (in cases where the backtrace is immediately
// streamed out, so we only need temporary references to external buffers);
// these pointers may be null for empty backtraces.
class ProfilerBacktrace {
// Take ownership of external buffers and use them to keep, and to stream a
// backtrace. If a ProfileBuffer is given, its underlying chunked buffer must
// be provided as well.
explicit ProfilerBacktrace(
const char* aName,
mozilla::UniquePtr<ProfileBuffer> aProfileBufferStorageOrNull = nullptr);
// Take pointers to external buffers and use them to stream a backtrace.
// If null, the backtrace is effectively empty.
// If both are provided, they must already be connected.
explicit ProfilerBacktrace(
const char* aName,
mozilla::ProfileChunkedBuffer* aExternalProfileChunkedBufferOrNull =
ProfileBuffer* aExternalProfileBufferOrNull = nullptr);
[[nodiscard]] bool IsEmpty() const {
return !mProfileChunkedBuffer ||
mozilla::ProfileChunkedBuffer>::Bytes(*mProfileChunkedBuffer) <=
// ProfilerBacktraces' stacks are deduplicated in the context of the
// profile that contains the backtrace as a marker payload.
// That is, markers that contain backtraces should not need their own stack,
// frame, and string tables. They should instead reuse their parent
// profile's tables.
ProfilerThreadId StreamJSON(
mozilla::baseprofiler::SpliceableJSONWriter& aWriter,
const mozilla::TimeStamp& aProcessStartTime, UniqueStacks& aUniqueStacks);
// Used to serialize a ProfilerBacktrace.
friend struct mozilla::ProfileBufferEntryWriter::Serializer<
friend struct mozilla::ProfileBufferEntryReader::Deserializer<
std::string mName;
// `ProfileChunkedBuffer` in which `mProfileBuffer` stores its data; must be
// located before `mProfileBuffer` so that it's destroyed after.
// If null, there is no need to check mProfileBuffer's (if present) underlying
// buffer because this is done when constructed.
mozilla::ProfileChunkedBuffer* mProfileChunkedBuffer;
mozilla::UniquePtr<ProfileBuffer> mOptionalProfileBufferStorage;
ProfileBuffer* mProfileBuffer;
namespace mozilla {
// Format: [ UniquePtr<BlockRingsBuffer> | name ]
// Initial len==0 marks a nullptr or empty backtrace.
template <>
struct mozilla::ProfileBufferEntryWriter::Serializer<ProfilerBacktrace> {
static Length Bytes(const ProfilerBacktrace& aBacktrace) {
if (!aBacktrace.mProfileChunkedBuffer) {
// No buffer.
return ULEB128Size(0u);
auto bufferBytes = SumBytes(*aBacktrace.mProfileChunkedBuffer);
if (bufferBytes <= ULEB128Size(0u)) {
// Empty buffer.
return ULEB128Size(0u);
return bufferBytes + SumBytes(aBacktrace.mName);
static void Write(mozilla::ProfileBufferEntryWriter& aEW,
const ProfilerBacktrace& aBacktrace) {
if (!aBacktrace.mProfileChunkedBuffer ||
SumBytes(*aBacktrace.mProfileChunkedBuffer) <= ULEB128Size(0u)) {
// No buffer, or empty buffer.
template <typename Destructor>
struct mozilla::ProfileBufferEntryWriter::Serializer<
mozilla::UniquePtr<ProfilerBacktrace, Destructor>> {
static Length Bytes(
const mozilla::UniquePtr<ProfilerBacktrace, Destructor>& aBacktrace) {
if (!aBacktrace) {
// Null backtrace pointer (treated like an empty backtrace).
return ULEB128Size(0u);
return SumBytes(*aBacktrace);
static void Write(
mozilla::ProfileBufferEntryWriter& aEW,
const mozilla::UniquePtr<ProfilerBacktrace, Destructor>& aBacktrace) {
if (!aBacktrace) {
// Null backtrace pointer (treated like an empty backtrace).
template <typename Destructor>
struct mozilla::ProfileBufferEntryReader::Deserializer<
mozilla::UniquePtr<ProfilerBacktrace, Destructor>> {
static void ReadInto(
mozilla::ProfileBufferEntryReader& aER,
mozilla::UniquePtr<ProfilerBacktrace, Destructor>& aBacktrace) {
aBacktrace = Read(aER);
static mozilla::UniquePtr<ProfilerBacktrace, Destructor> Read(
mozilla::ProfileBufferEntryReader& aER) {
auto profileChunkedBuffer =
if (!profileChunkedBuffer) {
return nullptr;
"ProfilerBacktrace only stores non-thread-safe ProfileChunkedBuffers");
std::string name = aER.ReadObject<std::string>();
return UniquePtr<ProfilerBacktrace, Destructor>{
new ProfilerBacktrace(name.c_str(), std::move(profileChunkedBuffer))};
} // namespace mozilla