1 files changed, 194 insertions, 0 deletions
diff --git a/src/runtime/trace2event.go b/src/runtime/trace2event.go
new file mode 100644
index 0000000..1f2a9f7
--- /dev/null
+++ b/src/runtime/trace2event.go
@@ -0,0 +1,194 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build goexperiment.exectracer2
+
+// Trace event writing API for trace2runtime.go.
+
+package runtime
+
+import (
+	"runtime/internal/sys"
+)
+
+// Event types in the trace, args are given in square brackets.
+//
+// Naming scheme:
+//   - Time range event pairs have suffixes "Begin" and "End".
+//   - "Start", "Stop", "Create", "Destroy", "Block", "Unblock"
+//     are suffixes reserved for scheduling resources.
+//
+// NOTE: If you add an event type, make sure you also update all
+// tables in this file!
+type traceEv uint8
+
+const (
+	traceEvNone traceEv = iota // unused
+
+	// Structural events.
+	traceEvEventBatch // start of per-M batch of events [generation, M ID, timestamp, batch length]
+	traceEvStacks     // start of a section of the stack table [...traceEvStack]
+	traceEvStack      // stack table entry [ID, ...{PC, func string ID, file string ID, line #}]
+	traceEvStrings    // start of a section of the string dictionary [...traceEvString]
+	traceEvString     // string dictionary entry [ID, length, string]
+	traceEvCPUSamples // start of a section of CPU samples [...traceEvCPUSample]
+	traceEvCPUSample  // CPU profiling sample [timestamp, M ID, P ID, goroutine ID, stack ID]
+	traceEvFrequency  // timestamp units per sec [freq]
+
+	// Procs.
+	traceEvProcsChange // current value of GOMAXPROCS [timestamp, GOMAXPROCS, stack ID]
+	traceEvProcStart   // start of P [timestamp, P ID, P seq]
+	traceEvProcStop    // stop of P [timestamp]
+	traceEvProcSteal   // P was stolen [timestamp, P ID, P seq, M ID]
+	traceEvProcStatus  // P status at the start of a generation [timestamp, P ID, status]
+
+	// Goroutines.
+	traceEvGoCreate            // goroutine creation [timestamp, new goroutine ID, new stack ID, stack ID]
+	traceEvGoCreateSyscall     // goroutine appears in syscall (cgo callback) [timestamp, new goroutine ID]
+	traceEvGoStart             // goroutine starts running [timestamp, goroutine ID, goroutine seq]
+	traceEvGoDestroy           // goroutine ends [timestamp]
+	traceEvGoDestroySyscall    // goroutine ends in syscall (cgo callback) [timestamp]
+	traceEvGoStop              // goroutine yields its time, but is runnable [timestamp, reason, stack ID]
+	traceEvGoBlock             // goroutine blocks [timestamp, reason, stack ID]
+	traceEvGoUnblock           // goroutine is unblocked [timestamp, goroutine ID, goroutine seq, stack ID]
+	traceEvGoSyscallBegin      // syscall enter [timestamp, P seq, stack ID]
+	traceEvGoSyscallEnd        // syscall exit [timestamp]
+	traceEvGoSyscallEndBlocked // syscall exit and it blocked at some point [timestamp]
+	traceEvGoStatus            // goroutine status at the start of a generation [timestamp, goroutine ID, M ID, status]
+
+	// STW.
+	traceEvSTWBegin // STW start [timestamp, kind]
+	traceEvSTWEnd   // STW done [timestamp]
+
+	// GC events.
+	traceEvGCActive           // GC active [timestamp, seq]
+	traceEvGCBegin            // GC start [timestamp, seq, stack ID]
+	traceEvGCEnd              // GC done [timestamp, seq]
+	traceEvGCSweepActive      // GC sweep active [timestamp, P ID]
+	traceEvGCSweepBegin       // GC sweep start [timestamp, stack ID]
+	traceEvGCSweepEnd         // GC sweep done [timestamp, swept bytes, reclaimed bytes]
+	traceEvGCMarkAssistActive // GC mark assist active [timestamp, goroutine ID]
+	traceEvGCMarkAssistBegin  // GC mark assist start [timestamp, stack ID]
+	traceEvGCMarkAssistEnd    // GC mark assist done [timestamp]
+	traceEvHeapAlloc          // gcController.heapLive change [timestamp, heap alloc in bytes]
+	traceEvHeapGoal           // gcController.heapGoal() change [timestamp, heap goal in bytes]
+
+	// Annotations.
+	traceEvGoLabel         // apply string label to current running goroutine [timestamp, label string ID]
+	traceEvUserTaskBegin   // trace.NewTask [timestamp, internal task ID, internal parent task ID, name string ID, stack ID]
+	traceEvUserTaskEnd     // end of a task [timestamp, internal task ID, stack ID]
+	traceEvUserRegionBegin // trace.{Start,With}Region [timestamp, internal task ID, name string ID, stack ID]
+	traceEvUserRegionEnd   // trace.{End,With}Region [timestamp, internal task ID, name string ID, stack ID]
+	traceEvUserLog         // trace.Log [timestamp, internal task ID, key string ID, stack, value string ID]
+)
+
+// traceArg is a simple wrapper type to help ensure that arguments passed
+// to traces are well-formed.
+type traceArg uint64
+
+// traceEventWriter is the high-level API for writing trace events.
+//
+// See the comment on traceWriter about style for more details as to why
+// this type and its methods are structured the way they are.
+type traceEventWriter struct {
+	w traceWriter
+}
+
+// eventWriter creates a new traceEventWriter. It is the main entrypoint for writing trace events.
+//
+// Before creating the event writer, this method will emit a status for the current goroutine
+// or proc if it exists, and if it hasn't had its status emitted yet. goStatus and procStatus indicate
+// what the status of goroutine or P should be immediately *before* the events that are about to
+// be written using the eventWriter (if they exist). No status will be written if there's no active
+// goroutine or P.
+//
+// Callers can elect to pass a constant value here if the status is clear (e.g. a goroutine must have
+// been Runnable before a GoStart). Otherwise, callers can query the status of either the goroutine
+// or P and pass the appropriate status.
+//
+// In this case, the default status should be traceGoBad or traceProcBad to help identify bugs sooner.
+func (tl traceLocker) eventWriter(goStatus traceGoStatus, procStatus traceProcStatus) traceEventWriter {
+	w := tl.writer()
+	if pp := tl.mp.p.ptr(); pp != nil && !pp.trace.statusWasTraced(tl.gen) && pp.trace.acquireStatus(tl.gen) {
+		w = w.writeProcStatus(uint64(pp.id), procStatus, pp.trace.inSweep)
+	}
+	if gp := tl.mp.curg; gp != nil && !gp.trace.statusWasTraced(tl.gen) && gp.trace.acquireStatus(tl.gen) {
+		w = w.writeGoStatus(uint64(gp.goid), int64(tl.mp.procid), goStatus, gp.inMarkAssist)
+	}
+	return traceEventWriter{w}
+}
+
+// commit writes out a trace event and calls end. It's a helper to make the
+// common case of writing out a single event less error-prone.
+func (e traceEventWriter) commit(ev traceEv, args ...traceArg) {
+	e = e.write(ev, args...)
+	e.end()
+}
+
+// write writes an event into the trace.
+func (e traceEventWriter) write(ev traceEv, args ...traceArg) traceEventWriter {
+	e.w = e.w.event(ev, args...)
+	return e
+}
+
+// end finishes writing to the trace. The traceEventWriter must not be used after this call.
+func (e traceEventWriter) end() {
+	e.w.end()
+}
+
+// traceEventWrite is the part of traceEvent that actually writes the event.
+func (w traceWriter) event(ev traceEv, args ...traceArg) traceWriter {
+	// Make sure we have room.
+	w, _ = w.ensure(1 + (len(args)+1)*traceBytesPerNumber)
+
+	// Compute the timestamp diff that we'll put in the trace.
+	ts := traceClockNow()
+	if ts <= w.traceBuf.lastTime {
+		ts = w.traceBuf.lastTime + 1
+	}
+	tsDiff := uint64(ts - w.traceBuf.lastTime)
+	w.traceBuf.lastTime = ts
+
+	// Write out event.
+	w.byte(byte(ev))
+	w.varint(tsDiff)
+	for _, arg := range args {
+		w.varint(uint64(arg))
+	}
+	return w
+}
+
+// stack takes a stack trace skipping the provided number of frames.
+// It then returns a traceArg representing that stack which may be
+// passed to write.
+func (tl traceLocker) stack(skip int) traceArg {
+	return traceArg(traceStack(skip, tl.mp, tl.gen))
+}
+
+// startPC takes a start PC for a goroutine and produces a unique
+// stack ID for it.
+//
+// It then returns a traceArg representing that stack which may be
+// passed to write.
+func (tl traceLocker) startPC(pc uintptr) traceArg {
+	// +PCQuantum because makeTraceFrame expects return PCs and subtracts PCQuantum.
+	return traceArg(trace.stackTab[tl.gen%2].put([]uintptr{
+		logicalStackSentinel,
+		startPCForTrace(pc) + sys.PCQuantum,
+	}))
+}
+
+// string returns a traceArg representing s which may be passed to write.
+// The string is assumed to be relatively short and popular, so it may be
+// stored for a while in the string dictionary.
+func (tl traceLocker) string(s string) traceArg {
+	return traceArg(trace.stringTab[tl.gen%2].put(tl.gen, s))
+}
+
+// uniqueString returns a traceArg representing s which may be passed to write.
+// The string is assumed to be unique or long, so it will be written out to
+// the trace eagerly.
+func (tl traceLocker) uniqueString(s string) traceArg {
+	return traceArg(trace.stringTab[tl.gen%2].emit(tl.gen, s))
+}