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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
#ifndef __PROFILER_BACKTRACE_H
#define __PROFILER_BACKTRACE_H
#include "mozilla/ProfileChunkedBuffer.h"
#include "mozilla/UniquePtr.h"
#include <string>
namespace mozilla {
class TimeStamp;
namespace baseprofiler {
class ProfileBuffer;
class SpliceableJSONWriter;
class ThreadInfo;
class UniqueStacks;
// 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 {
public:
// 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,
UniquePtr<ProfileChunkedBuffer> aProfileChunkedBufferStorage,
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,
ProfileChunkedBuffer* aExternalProfileChunkedBufferOrNull = nullptr,
ProfileBuffer* aExternalProfileBufferOrNull = nullptr);
~ProfilerBacktrace();
[[nodiscard]] bool IsEmpty() const {
return !mProfileChunkedBuffer ||
ProfileBufferEntryWriter::Serializer<ProfileChunkedBuffer>::Bytes(
*mProfileChunkedBuffer) <= ULEB128Size(0u);
}
// 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.
BaseProfilerThreadId StreamJSON(SpliceableJSONWriter& aWriter,
const TimeStamp& aProcessStartTime,
UniqueStacks& aUniqueStacks);
private:
// Used to de/serialize a ProfilerBacktrace.
friend ProfileBufferEntryWriter::Serializer<ProfilerBacktrace>;
friend ProfileBufferEntryReader::Deserializer<ProfilerBacktrace>;
std::string mName;
// `ProfileChunkedBuffer` in which `mProfileBuffer` stores its data; must be
// located before `mProfileBuffer` so that it's destroyed after.
UniquePtr<ProfileChunkedBuffer> mOptionalProfileChunkedBufferStorage;
// If null, there is no need to check mProfileBuffer's (if present) underlying
// buffer because this is done when constructed.
ProfileChunkedBuffer* mProfileChunkedBuffer;
UniquePtr<ProfileBuffer> mOptionalProfileBufferStorage;
ProfileBuffer* mProfileBuffer;
};
} // namespace baseprofiler
// Format: [ UniquePtr<BlockRingsBuffer> | name ]
// Initial len==0 marks a nullptr or empty backtrace.
template <>
struct ProfileBufferEntryWriter::Serializer<baseprofiler::ProfilerBacktrace> {
static Length Bytes(const baseprofiler::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(ProfileBufferEntryWriter& aEW,
const baseprofiler::ProfilerBacktrace& aBacktrace) {
if (!aBacktrace.mProfileChunkedBuffer ||
SumBytes(*aBacktrace.mProfileChunkedBuffer) <= ULEB128Size(0u)) {
// No buffer, or empty buffer.
aEW.WriteULEB128(0u);
return;
}
aEW.WriteObject(*aBacktrace.mProfileChunkedBuffer);
aEW.WriteObject(aBacktrace.mName);
}
};
template <typename Destructor>
struct ProfileBufferEntryWriter::Serializer<
UniquePtr<baseprofiler::ProfilerBacktrace, Destructor>> {
static Length Bytes(const UniquePtr<baseprofiler::ProfilerBacktrace,
Destructor>& aBacktrace) {
if (!aBacktrace) {
// Null backtrace pointer (treated like an empty backtrace).
return ULEB128Size(0u);
}
return SumBytes(*aBacktrace);
}
static void Write(ProfileBufferEntryWriter& aEW,
const UniquePtr<baseprofiler::ProfilerBacktrace,
Destructor>& aBacktrace) {
if (!aBacktrace) {
// Null backtrace pointer (treated like an empty backtrace).
aEW.WriteULEB128(0u);
return;
}
aEW.WriteObject(*aBacktrace);
}
};
template <typename Destructor>
struct ProfileBufferEntryReader::Deserializer<
UniquePtr<baseprofiler::ProfilerBacktrace, Destructor>> {
static void ReadInto(
ProfileBufferEntryReader& aER,
UniquePtr<baseprofiler::ProfilerBacktrace, Destructor>& aBacktrace) {
aBacktrace = Read(aER);
}
static UniquePtr<baseprofiler::ProfilerBacktrace, Destructor> Read(
ProfileBufferEntryReader& aER);
};
} // namespace mozilla
#endif // __PROFILER_BACKTRACE_H