feat: Add initial profiling support

_examples/profiling/main.go

@@ -0,0 +1,80 @@
+//	go run main.go
+//
+// To actually report events to Sentry, set the DSN either by editing the
+// appropriate line below or setting the environment variable SENTRY_DSN to
+// match the DSN of your Sentry project.
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"runtime"
+	"sync"
+	"time"
+
+	"github.com/getsentry/sentry-go"
+)
+
+func main() {
+	err := sentry.Init(sentry.ClientOptions{
+		// Either set your DSN here or set the SENTRY_DSN environment variable.
+		Dsn: "",
+		// Enable printing of SDK debug messages.
+		// Useful when getting started or trying to figure something out.
+		Debug:              true,
+		EnableTracing:      true,
+		TracesSampleRate:   1.0,
+		ProfilesSampleRate: 1.0,
+	})
+
+	// Flush buffered events before the program terminates.
+	// Set the timeout to the maximum duration the program can afford to wait.
+	defer sentry.Flush(2 * time.Second)
+
+	if err != nil {
+		log.Fatalf("sentry.Init: %s", err)
+	}
+	ctx := context.Background()
+	tx := sentry.StartTransaction(ctx, "top")
+
+	fmt.Println("Finding prime numbers")
+	var wg sync.WaitGroup
+	wg.Add(10)
+	for i := 0; i < 10; i++ {
+		go func(num int) {
+			span := tx.StartChild(fmt.Sprintf("Goroutine %d", num))
+			defer span.Finish()
+			for i := 0; i < num; i++ {
+				_ = findPrimeNumber(50000)
+				runtime.Gosched() // we need to manually yield this busy loop
+			}
+			fmt.Printf("routine %d done\n", num)
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+	fmt.Println("all")
+	tx.Finish()
+}
+
+func findPrimeNumber(n int) int {
+	count := 0
+	a := 2
+	for count < n {
+		b := 2
+		prime := true // to check if found a prime
+		for b*b <= a {
+			if a%b == 0 {
+				prime = false
+				break
+			}
+			b++
+		}
+		if prime {
+			count++
+		}
+		a++
+	}
+	return a - 1
+}

client.go

@@ -130,6 +130,9 @@ type ClientOptions struct {
 	TracesSampleRate float64
 	// Used to customize the sampling of traces, overrides TracesSampleRate.
 	TracesSampler TracesSampler
+	// The sample rate for profiling traces in the range [0.0, 1.0].
+	// This applies on top of TracesSampleRate - it is a ratio of profiled traces out of all sampled traces.
+	ProfilesSampleRate float64
 	// List of regexp strings that will be used to match against event's message
 	// and if applicable, caught errors type and value.
 	// If the match is found, then a whole event will be dropped.
@@ -371,6 +374,7 @@ func (client *Client) AddEventProcessor(processor EventProcessor) {
 }
 
 // Options return ClientOptions for the current Client.
+// TODO don't access this internally to avoid creating a copy each time.
 func (client Client) Options() ClientOptions {
 	return client.options
 }
@@ -573,6 +577,7 @@ func (client *Client) processEvent(event *Event, hint *EventHint, scope EventMod
 
 func (client *Client) prepareEvent(event *Event, hint *EventHint, scope EventModifier) *Event {
 	if event.EventID == "" {
+		// TODO set EventID when the event is created, same as in other SDKs. It's necessary for profileTransaction.ID.
 		event.EventID = EventID(uuid())
 	}
 

client_test.go

@@ -79,7 +79,7 @@ func TestCaptureMessageEmptyString(t *testing.T) {
 	}
 	got := transport.lastEvent
 	opts := cmp.Options{
-		cmpopts.IgnoreFields(Event{}, "sdkMetaData"),
+		cmpopts.IgnoreFields(Event{}, "sdkMetaData", "transactionProfile"),
 		cmp.Transformer("SimplifiedEvent", func(e *Event) *Event {
 			return &Event{
 				Exception: e.Exception,
@@ -286,7 +286,7 @@ func TestCaptureEvent(t *testing.T) {
 		},
 	}
 	got := transport.lastEvent
-	opts := cmp.Options{cmpopts.IgnoreFields(Event{}, "Release", "sdkMetaData")}
+	opts := cmp.Options{cmpopts.IgnoreFields(Event{}, "Release", "sdkMetaData", "transactionProfile")}
 	if diff := cmp.Diff(want, got, opts); diff != "" {
 		t.Errorf("Event mismatch (-want +got):\n%s", diff)
 	}
@@ -314,7 +314,7 @@ func TestCaptureEventNil(t *testing.T) {
 	}
 	got := transport.lastEvent
 	opts := cmp.Options{
-		cmpopts.IgnoreFields(Event{}, "sdkMetaData"),
+		cmpopts.IgnoreFields(Event{}, "sdkMetaData", "transactionProfile"),
 		cmp.Transformer("SimplifiedEvent", func(e *Event) *Event {
 			return &Event{
 				Exception: e.Exception,
@@ -538,7 +538,7 @@ func TestRecover(t *testing.T) {
 		}
 		got := events[0]
 		opts := cmp.Options{
-			cmpopts.IgnoreFields(Event{}, "sdkMetaData"),
+			cmpopts.IgnoreFields(Event{}, "sdkMetaData", "transactionProfile"),
 			cmp.Transformer("SimplifiedEvent", func(e *Event) *Event {
 				return &Event{
 					Message:   e.Message,

fasthttp/sentryfasthttp_test.go

@@ -207,7 +207,7 @@ func TestIntegration(t *testing.T) {
 			sentry.Event{},
 			"Contexts", "EventID", "Extra", "Platform", "Modules",
 			"Release", "Sdk", "ServerName", "Tags", "Timestamp",
-			"sdkMetaData",
+			"sdkMetaData","transactionProfile",
 		),
 		cmpopts.IgnoreMapEntries(func(k string, v string) bool {
 			// fasthttp changed Content-Length behavior in

http/sentryhttp_test.go

@@ -210,7 +210,7 @@ func TestIntegration(t *testing.T) {
 			sentry.Event{},
 			"Contexts", "EventID", "Extra", "Platform", "Modules",
 			"Release", "Sdk", "ServerName", "Tags", "Timestamp",
-			"sdkMetaData",
+			"sdkMetaData", "transactionProfile",
 		),
 		cmpopts.IgnoreFields(
 			sentry.Request{},

interfaces.go

@@ -20,6 +20,8 @@ const transactionType = "transaction"
 // eventType is the type of an error event.
 const eventType = "event"
 
+const profileType = "profile"
+
 // Level marks the severity of the event.
 type Level string
 
@@ -315,6 +317,9 @@ type Event struct {
 	// The fields below are not part of the final JSON payload.
 
 	sdkMetaData SDKMetaData
+
+	// TODO remove once https://github.com/getsentry/sentry-go/issues/629 is implemented
+	transactionProfile *profileInfo
 }
 
 // SetException appends the unwrapped errors to the event's exception list.

internal/traceparser/README.md

@@ -0,0 +1,13 @@
+## Benchmark results
+
+```
+goos: windows
+goarch: amd64
+pkg: github.com/getsentry/sentry-go/internal/trace
+cpu: 12th Gen Intel(R) Core(TM) i7-12700K
+BenchmarkEqualBytes-20          42332671                25.99 ns/op
+BenchmarkStringEqual-20         70265427                17.02 ns/op
+BenchmarkEqualPrefix-20         42128026                30.14 ns/op
+BenchmarkFullParse-20             738534              1501 ns/op        1358.56 MB/s        1024 B/op          6 allocs/op
+BenchmarkSplitOnly-20            2298318               524.6 ns/op      3886.65 MB/s         128 B/op          1 allocs/op
+```

internal/traceparser/parser.go

@@ -0,0 +1,165 @@
+package traceparser
+
+import (
+	"bytes"
+	"strconv"
+)
+
+var blockSeparator = []byte("\n\n")
+var lineSeparator = []byte("\n")
+
+// Parses multi-stacktrace text dump produced by runtime.Stack([]byte, all=true).
+// The parser prioritizes performance but requires the input to be well-formed in order to return correct data.
+// See https://cs.opensource.google/go/go/+/refs/tags/go1.20.4:src/runtime/mprof.go;l=1191
+func Parse(data []byte) TraceCollection {
+	var it = TraceCollection{}
+	if len(data) > 0 {
+		it.blocks = bytes.Split(data, blockSeparator)
+		it.Length = len(it.blocks)
+	}
+	return it
+}
+
+type TraceCollection struct {
+	Length int
+	blocks [][]byte
+}
+
+// Returns the stacktrace item at the given index.
+func (it *TraceCollection) Item(i int) Trace {
+	// The first item may have a leading data separator and the last one may have a trailing one.
+	// Note: Trim() doesn't make a copy for single-character cutset under 0x80. It will just slice the original.
+	var data []byte
+	if i == 0 {
+		data = bytes.TrimLeft(it.blocks[i], "\n")
+	} else if i == len(it.blocks)-1 {
+		data = bytes.TrimRight(it.blocks[i], "\n")
+	} else {
+		data = it.blocks[i]
+	}
+
+	var splitAt = bytes.IndexByte(data, '\n')
+	if splitAt < 0 {
+		return Trace{header: data}
+	}
+
+	return Trace{
+		header: data[:splitAt],
+		data:   data[splitAt+1:],
+	}
+}
+
+// Trace represents a single stacktrace block, identified by a Goroutine ID and a sequence of Frames.
+type Trace struct {
+	header []byte
+	data   []byte
+}
+
+var goroutinePrefix = []byte("goroutine ")
+
+// GoID parses the Goroutine ID from the header.
+func (t *Trace) GoID() (id uint64) {
+	if bytes.HasPrefix(t.header, goroutinePrefix) {
+		var line = t.header[len(goroutinePrefix):]
+		var splitAt = bytes.IndexByte(line, ' ')
+		if splitAt >= 0 {
+			id, _ = strconv.ParseUint(string(line[:splitAt]), 10, 64)
+		}
+	}
+	return id
+}
+
+// UniqueIdentifier can be used as a map key to identify the trace.
+func (t *Trace) UniqueIdentifier() []byte {
+	return t.data
+}
+
+func (t *Trace) FramesReversed() ReverseFrameIterator {
+	var lines = bytes.Split(t.data, lineSeparator)
+	return ReverseFrameIterator{lines: lines, i: len(lines)}
+}
+
+// ReverseFrameIterator iterates over stack frames in reverse order.
+type ReverseFrameIterator struct {
+	lines [][]byte
+	i     int
+}
+
+// Next returns the next frame, or nil if there are none.
+func (it *ReverseFrameIterator) Next() Frame {
+	var line2 = it.popLine()
+	return Frame{it.popLine(), line2}
+}
+
+const framesElided = "...additional frames elided..."
+
+func (it *ReverseFrameIterator) popLine() []byte {
+	it.i--
+	if it.i < 0 {
+		return nil
+	}
+	if string(it.lines[it.i]) == framesElided {
+		return it.popLine()
+	} else {
+		return it.lines[it.i]
+	}
+}
+
+// HasNext return true if there are values to be read.
+func (it *ReverseFrameIterator) HasNext() bool {
+	return it.i > 1
+}
+
+// LengthUpperBound returns the maximum number of elemnt this stacks may contain.
+// The actual number may be lower because of elided frames. As such, the returned value
+// cannot be used to iterate over the frames but may be used to reserve capacity.
+func (it *ReverseFrameIterator) LengthUpperBound() int {
+	return len(it.lines) / 2
+}
+
+type Frame struct {
+	line1 []byte
+	line2 []byte
+}
+
+// UniqueIdentifier can be used as a map key to identify the frame.
+func (t *Frame) UniqueIdentifier() []byte {
+	// line2 contains file path, line number and program-counter offset from the beginning of a function
+	// e.g. C:/Users/name/scoop/apps/go/current/src/testing/testing.go:1906 +0x63a
+	return t.line2
+}
+
+var createdByPrefix = []byte("created by ")
+
+func (f *Frame) Func() []byte {
+	if bytes.HasPrefix(f.line1, createdByPrefix) {
+		return f.line1[len(createdByPrefix):]
+	}
+
+	var end = bytes.LastIndexByte(f.line1, '(')
+	if end >= 0 {
+		return f.line1[:end]
+	}
+
+	return f.line1
+}
+
+func (f *Frame) File() (path []byte, lineNumber int) {
+	var line = f.line2
+	if len(line) > 0 && line[0] == '\t' {
+		line = line[1:]
+	}
+
+	var splitAt = bytes.IndexByte(line, ' ')
+	if splitAt >= 0 {
+		line = line[:splitAt]
+	}
+
+	splitAt = bytes.LastIndexByte(line, ':')
+	if splitAt < 0 {
+		return line, 0
+	}
+
+	lineNumber, _ = strconv.Atoi(string(line[splitAt+1:]))
+	return line[:splitAt], lineNumber
+}