zen trace analysis support (#945)

Integrates the **tourist** trace analysis library and builds a full `zen trace` command suite for working with Unreal Engine `.utrace` files.

### Trace analysis library (`thirdparty/tourist/`)
- Adds the tourist library as a third-party dependency with three modules: **foundation** (platform primitives, memory, scheduling), **trace** (UE Trace protocol decoding), and **analysis** (event dispatching and analyzer framework).
- Cross-platform support for Windows, Linux, and macOS.

### `zen trace` CLI commands (`src/zen/cmds/`, `src/zen/trace/`)
- **`zen trace analyze`** — Summarize a `.utrace` file: session metadata, thread inventory, command line + build configuration, CPU profiling scopes, timing, event rates, log messages, and (with symbols) memory allocation metrics including live-allocs dumps, callstack-keyed aggregation, and allocation churn. Optional HTML output for memory reports.
- **`zen trace inspect`** — Dump the event schema (declared types, fields, sizes) from a trace file.
- **`zen trace trim`** — Extract a time-window from a trace into a new `.utrace` file.
- **`zen trace serve`** — Launch a local HTTP server hosting an interactive trace viewer; opens in the default browser.

### Symbolication (`src/zen/trace/symbol_resolver.*`, `thirdparty/raw_pdb/`)
- Pluggable resolver with multiple backends: `pdb` (in-tree raw_pdb), `dbghelp` (Windows), `llvm-symbolizer` (all platforms), `atos` (macOS). An `auto` backend picks the best available tool per platform.
- Microsoft Symbol Server support: downloads PDBs on demand using a redirect-aware HTTP client.
- Local PDB cache keyed by image GUID preserves symbols across binary recompilation.
- Callstack trimming heuristic strips UE internal noise from reports.
- Binary analysis cache (`.ucache_z`) avoids re-resolving the same trace.

### Interactive trace viewer (`src/zen/frontend/html/`, `src/zen/trace/trace_viewer_service.*`)
- Timeline: scope-level detail, horizontal zoom/pan, vertical scrolling, viewport-driven loading with pre-computed LOD for responsive navigation of large traces.
- Thread grouping (collapsible sidebar sections) synthesized from name suffixes, natural sort order, visual distinction between lane threads and OS threads.
- Bookmark and region annotations; region categories with per-category toggles; bookmark marker toggle in the toolbar.
- Filterable Logs tab showing captured `UE_LOG` output.
- Stats tab with per-scope aggregate statistics.
- Memory tab with interactive allocation analysis and an allocation size histogram.
- CsvProfiler event parsing and chart UI.

### Other in-branch supporting changes
- **Cross-platform browser launcher** (`browser_launcher.{h,cpp}`) used by `trace serve`.
- **`ReciprocalU64`** fast 64-bit integer division (zencore/intmath) for trace analyzers.
- **`parallelsort`** cross-platform parallel sort helper (zenutil).
- Frontend zip build rule so the viewer's HTML assets are bundled into `zen.exe`.
- `/Zo` flag for better optimized debug info on Windows release builds.
- `trace-tests.cpp` in the `zen-test` harness (harness itself landed on main via #985).

1 files changed, 335 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/PDB_DBIStream.cpp b/thirdparty/raw_pdb/src/PDB_DBIStream.cpp
new file mode 100644
index 000000000..5c9bf1512
--- /dev/null
+++ b/thirdparty/raw_pdb/src/PDB_DBIStream.cpp
@@ -0,0 +1,335 @@
+// Copyright 2011-2022, Molecular Matters GmbH <[email protected]>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "PDB_PCH.h"
+#include "PDB_DBIStream.h"
+#include "PDB_RawFile.h"
+
+
+namespace
+{
+	// the DBI stream always resides at index 3
+	static constexpr const uint32_t DBIStreamIndex = 3u;
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetModuleInfoSubstreamOffset(const PDB::DBI::StreamHeader& /* dbiHeader */) PDB_NO_EXCEPT
+	{
+		return sizeof(PDB::DBI::StreamHeader);
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetSectionContributionSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetModuleInfoSubstreamOffset(dbiHeader) + dbiHeader.moduleInfoSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetSectionMapSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetSectionContributionSubstreamOffset(dbiHeader) + dbiHeader.sectionContributionSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetSourceInfoSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetSectionMapSubstreamOffset(dbiHeader) + dbiHeader.sectionMapSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetTypeServerMapSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetSourceInfoSubstreamOffset(dbiHeader) + dbiHeader.sourceInfoSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetECSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetTypeServerMapSubstreamOffset(dbiHeader) + dbiHeader.typeServerMapSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline uint32_t GetDebugHeaderSubstreamOffset(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return GetECSubstreamOffset(dbiHeader) + dbiHeader.ecSize;
+	}
+
+
+	// ------------------------------------------------------------------------------------------------
+	// ------------------------------------------------------------------------------------------------
+	PDB_NO_DISCARD static inline bool HasDebugHeaderSubstream(const PDB::DBI::StreamHeader& dbiHeader) PDB_NO_EXCEPT
+	{
+		return dbiHeader.optionalDebugHeaderSize != 0u;
+	}
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB::DBIStream::DBIStream(void) PDB_NO_EXCEPT
+	: m_header()
+	, m_stream()
+{
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB::DBIStream::DBIStream(const RawFile& file, const DBI::StreamHeader& header) PDB_NO_EXCEPT
+	: m_header(header)
+	, m_stream(file.CreateMSFStream<DirectMSFStream>(DBIStreamIndex))
+{
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::HasValidDBIStream(const RawFile& file) PDB_NO_EXCEPT
+{
+	DirectMSFStream stream = file.CreateMSFStream<DirectMSFStream>(DBIStreamIndex);
+	if (stream.GetSize() < sizeof(DBI::StreamHeader))
+	{
+		return ErrorCode::InvalidStream;
+	}
+
+	const DBI::StreamHeader header = stream.ReadAtOffset<DBI::StreamHeader>(0u);
+	if (header.signature != DBI::StreamHeader::Signature)
+	{
+		return ErrorCode::InvalidSignature;
+	}
+	else if (header.version != DBI::StreamHeader::Version::V70)
+	{
+		return ErrorCode::UnknownVersion;
+	}
+
+	return ErrorCode::Success;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::DBIStream PDB::CreateDBIStream(const RawFile& file) PDB_NO_EXCEPT
+{
+	DirectMSFStream stream = file.CreateMSFStream<DirectMSFStream>(DBIStreamIndex);
+	const DBI::StreamHeader header = stream.ReadAtOffset<DBI::StreamHeader>(0u);
+
+	return DBIStream { file, header };
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::DBIStream::HasValidSymbolRecordStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	return (m_header.symbolRecordStreamIndex != PDB::NilStreamIndex) ? ErrorCode::Success : ErrorCode::InvalidStreamIndex;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::DBIStream::HasValidImageSectionStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	// the debug header stream is optional. if it's not there, we can't get the image section stream either.
+	if (!HasDebugHeaderSubstream(m_header))
+	{
+		return ErrorCode::InvalidStreamIndex;
+	}
+
+	// find the debug header sub-stream
+	const uint32_t debugHeaderOffset = GetDebugHeaderSubstreamOffset(m_header);
+
+	// validate that we have enough data to read the debug header
+	// (the header field optionalDebugHeaderSize might claim there's a debug header,
+	// but the stream might not have enough data - this happens with some .ni.pdb files)
+	if (debugHeaderOffset + sizeof(DBI::DebugHeader) > m_stream.GetSize())
+	{
+		return ErrorCode::InvalidStream;
+	}
+
+	const DBI::DebugHeader& debugHeader = m_stream.ReadAtOffset<DBI::DebugHeader>(debugHeaderOffset);
+
+	if (debugHeader.sectionHeaderStreamIndex == DBI::DebugHeader::InvalidStreamIndex)
+	{
+		return ErrorCode::InvalidStreamIndex;
+	}
+
+	return ErrorCode::Success;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::DBIStream::HasValidPublicSymbolStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	if (m_header.publicStreamIndex == PDB::NilStreamIndex)
+	{
+		return ErrorCode::InvalidStreamIndex;
+	}
+
+	DirectMSFStream publicStream = file.CreateMSFStream<DirectMSFStream>(m_header.publicStreamIndex);
+
+	// the public symbol stream always begins with a header, we are not interested in that.
+	// following the public symbol stream header is a hash table header.
+	const HashTableHeader hashHeader = publicStream.ReadAtOffset<HashTableHeader>(sizeof(PublicStreamHeader));
+	if (hashHeader.signature != HashTableHeader::Signature)
+	{
+		return ErrorCode::InvalidSignature;
+	}
+	else if (hashHeader.version != HashTableHeader::Version)
+	{
+		return ErrorCode::UnknownVersion;
+	}
+
+	return ErrorCode::Success;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::DBIStream::HasValidGlobalSymbolStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	if (m_header.globalStreamIndex == PDB::NilStreamIndex)
+	{
+		return ErrorCode::InvalidStreamIndex;
+	}
+
+	DirectMSFStream globalStream = file.CreateMSFStream<DirectMSFStream>(m_header.globalStreamIndex);
+
+	// the global symbol stream starts with a hash table header
+	const HashTableHeader hashHeader = globalStream.ReadAtOffset<HashTableHeader>(0u);
+	if (hashHeader.signature != HashTableHeader::Signature)
+	{
+		return ErrorCode::InvalidSignature;
+	}
+	else if (hashHeader.version != HashTableHeader::Version)
+	{
+		return ErrorCode::UnknownVersion;
+	}
+
+	return ErrorCode::Success;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ErrorCode PDB::DBIStream::HasValidSectionContributionStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	if (m_header.sectionContributionSize < sizeof(DBI::SectionContribution::Version))
+	{
+		return ErrorCode::InvalidStream;
+	}
+
+	// find the section contribution sub-stream
+	// https://llvm.org/docs/PDB/DbiStream.html#section-contribution-substream
+	const uint32_t streamOffset = GetSectionContributionSubstreamOffset(m_header);
+
+	const DBI::SectionContribution::Version version = m_stream.ReadAtOffset<DBI::SectionContribution::Version>(streamOffset);
+	if (version != DBI::SectionContribution::Version::Ver60)
+	{
+		return ErrorCode::UnknownVersion;
+	}
+
+	return ErrorCode::Success;
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::CoalescedMSFStream PDB::DBIStream::CreateSymbolRecordStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	// the symbol record stream holds the actual CodeView data of the symbols
+	return file.CreateMSFStream<CoalescedMSFStream>(m_header.symbolRecordStreamIndex);
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ImageSectionStream PDB::DBIStream::CreateImageSectionStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	// find the debug header sub-stream
+	const uint32_t debugHeaderOffset = GetDebugHeaderSubstreamOffset(m_header);
+	const DBI::DebugHeader& debugHeader = m_stream.ReadAtOffset<DBI::DebugHeader>(debugHeaderOffset);
+
+	// from there, grab the section header stream
+	return ImageSectionStream(file, debugHeader.sectionHeaderStreamIndex);
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::PublicSymbolStream PDB::DBIStream::CreatePublicSymbolStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	DirectMSFStream publicStream = file.CreateMSFStream<DirectMSFStream>(m_header.publicStreamIndex);
+
+	// the public symbol stream always begins with a header, we are not interested in that.
+	// following the public symbol stream header is a hash table header.
+	// we use this to work out how many symbol records are referenced by the public symbol stream.
+	const HashTableHeader hashHeader = publicStream.ReadAtOffset<HashTableHeader>(sizeof(PublicStreamHeader));
+	const uint32_t recordCount = hashHeader.size / sizeof(HashRecord);
+
+	return PublicSymbolStream(file, m_header.publicStreamIndex, recordCount);
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::GlobalSymbolStream PDB::DBIStream::CreateGlobalSymbolStream(const RawFile& file) const PDB_NO_EXCEPT
+{
+	DirectMSFStream globalStream = file.CreateMSFStream<DirectMSFStream>(m_header.globalStreamIndex);
+
+	// the global symbol stream starts with a hash table header.
+	// we use this to work out how many symbol records are referenced by the global symbol stream.
+	const HashTableHeader hashHeader = globalStream.ReadAtOffset<HashTableHeader>(0u);
+	const uint32_t recordCount = hashHeader.size / sizeof(HashRecord);
+
+	return GlobalSymbolStream(file, m_header.globalStreamIndex, recordCount);
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::SourceFileStream PDB::DBIStream::CreateSourceFileStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	// find the source info sub-stream
+	// https://llvm.org/docs/PDB/DbiStream.html#file-info-substream
+	const uint32_t streamOffset = GetSourceInfoSubstreamOffset(m_header);
+
+	return SourceFileStream(m_stream, m_header.sourceInfoSize, streamOffset);
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::SectionContributionStream PDB::DBIStream::CreateSectionContributionStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	// find the section contribution sub-stream
+	// https://llvm.org/docs/PDB/DbiStream.html#section-contribution-substream
+	const uint32_t streamOffset = GetSectionContributionSubstreamOffset(m_header);
+
+	return SectionContributionStream(m_stream, m_header.sectionContributionSize - sizeof(DBI::SectionContribution::Version), streamOffset + sizeof(DBI::SectionContribution::Version));
+}
+
+
+// ------------------------------------------------------------------------------------------------
+// ------------------------------------------------------------------------------------------------
+PDB_NO_DISCARD PDB::ModuleInfoStream PDB::DBIStream::CreateModuleInfoStream(const RawFile& /* file */) const PDB_NO_EXCEPT
+{
+	// find the module info sub-stream
+	// https://llvm.org/docs/PDB/DbiStream.html#module-info-substream
+	const uint32_t streamOffset = GetModuleInfoSubstreamOffset(m_header);
+
+	return ModuleInfoStream(m_stream, m_header.moduleInfoSize, streamOffset);
+}