feat(otelglobal): add support for Span SetName

CHANGELOG.md

@@ -8,6 +8,9 @@ OpenTelemetry Go Automatic Instrumentation adheres to [Semantic Versioning](http
 
 ## [Unreleased]
 
+### Added
+- Add support for manual instrumentation with Span `SetName`. ([#590](https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/590))
+
 ## [v0.10.0-alpha] - 2024-01-03
 
 ### Added

internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/bpf/probe.bpf.c

@@ -64,6 +64,14 @@ struct {
 // Injected in init
 volatile const u64 tracer_delegate_pos;
 
+
+// span_name_read reads the span name from the provided span_name_ptr and stores the result in
+// span_name.buf.
+static __always_inline void span_name_read(void *span_name_ptr, struct span_name_t span_name, const u64 span_name_len) {
+    const u64 span_name_size = MAX_SPAN_NAME_LEN < span_name_len ? MAX_SPAN_NAME_LEN : span_name_len;
+    bpf_probe_read(span_name.buf, span_name_size, span_name_ptr);
+}
+
 // This instrumentation attaches uprobe to the following function:
 // func (t *tracer) Start(ctx context.Context, name string, opts ...trace.SpanStartOption) (context.Context, trace.Span)
 // https://github.com/open-telemetry/opentelemetry-go/blob/98b32a6c3a87fbee5d34c063b9096f416b250897/internal/global/trace.go#L149
@@ -81,8 +89,7 @@ int uprobe_Start(struct pt_regs *ctx) {
     // Getting span name
     void *span_name_ptr = get_argument(ctx, 4);
     u64 span_name_len = (u64)get_argument(ctx, 5);
-    u64 span_name_size = MAX_SPAN_NAME_LEN < span_name_len ? MAX_SPAN_NAME_LEN : span_name_len;
-    bpf_probe_read(span_name.buf, span_name_size, span_name_ptr);
+    span_name_read(span_name_ptr, span_name, span_name_len);
 
     // Save the span name in map to be read once the Start function returns
     void *context_ptr_val = get_Go_context(ctx, 3, 0, true);
@@ -162,6 +169,32 @@ int uprobe_SetAttributes(struct pt_regs *ctx) {
     return 0;
 }
 
+// This instrumentation attaches uprobe to the following function:
+// func (nonRecordingSpan) SetName(string)
+SEC("uprobe/SetName")
+int uprobe_SetName(struct pt_regs *ctx) {
+    void *non_recording_span_ptr = get_argument(ctx, 1);
+    struct otel_span_t *span = bpf_map_lookup_elem(&active_spans_by_span_ptr, &non_recording_span_ptr);
+    if (span == NULL) {
+        return 0;
+    }
+
+    struct span_name_t span_name = {0};
+
+    // Getting span name
+    void *span_name_ptr = get_argument(ctx, 4);
+    if (span_name_ptr == NULL) {
+        return 0;
+    }
+
+    u64 span_name_len = (u64)get_argument(ctx, 5);
+
+    span_name_read(span_name_ptr, span_name, span_name_len);
+    span->span_name = span_name;
+
+    bpf_map_update_elem(&active_spans_by_span_ptr, &non_recording_span_ptr, span, 0);
+    return 0;
+}
 
 // This instrumentation attaches uprobe to the following function:
 // func (*nonRecordingSpan) End(...trace.SpanEndOption)
@@ -178,4 +211,4 @@ int uprobe_End(struct pt_regs *ctx) {
 
     bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, span, sizeof(*span));
     return 0;
-}
+}

internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go

@@ -99,14 +99,19 @@ func New(logger logr.Logger) probe.Probe {
 				Sym: "go.opentelemetry.io/otel/internal/global.(*tracer).Start",
 				Fn:  uprobeTracerStart,
 			},
+			{
+				Sym: "go.opentelemetry.io/otel/internal/global.(*nonRecordingSpan).End",
+				Fn:  uprobeSpanEnd,
+			},
 			{
 				Sym:      "go.opentelemetry.io/otel/internal/global.(*nonRecordingSpan).SetAttributes",
 				Fn:       uprobeSetAttributes,
 				Optional: true,
 			},
 			{
-				Sym: "go.opentelemetry.io/otel/internal/global.(*nonRecordingSpan).End",
-				Fn:  uprobeSpanEnd,
+				Sym:      "go.opentelemetry.io/otel/internal/global.(*nonRecordingSpan).SetName",
+				Fn:       uprobeSpanSetName,
+				Optional: true,
 			},
 		},
 
@@ -166,6 +171,23 @@ func uprobeSetAttributes(name string, exec *link.Executable, target *process.Tar
 	return links, nil
 }
 
+func uprobeSpanSetName(name string, exec *link.Executable, target *process.TargetDetails, obj *bpfObjects) ([]link.Link, error) {
+	offset, err := target.GetFunctionOffset(name)
+	if err != nil {
+		return nil, err
+	}
+
+	opts := &link.UprobeOptions{Address: offset}
+	l, err := exec.Uprobe("", obj.UprobeSetName, opts)
+	if err != nil {
+		return nil, err
+	}
+
+	links := []link.Link{l}
+
+	return links, nil
+}
+
 func uprobeSpanEnd(name string, exec *link.Executable, target *process.TargetDetails, obj *bpfObjects) ([]link.Link, error) {
 	offset, err := target.GetFunctionOffset(name)
 	if err != nil {

internal/test/e2e/otelglobal/main.go

@@ -31,11 +31,19 @@ func innerFunction(ctx context.Context) {
 	span.SetAttributes(attribute.String("inner.key", "inner.value"))
 }
 
+func setNameOverride(ctx context.Context) {
+	_, span := tracer.Start(ctx, "SetNameOriginal")
+	defer span.End()
+
+	span.SetName("SetNameOverride")
+}
+
 func createMainSpan(ctx context.Context) {
 	ctx, span := tracer.Start(ctx, "parent")
 	defer span.End()
 
 	innerFunction(ctx)
+	setNameOverride(ctx)
 
 	intAttr := attribute.Int("int_key", 42)
 	strAttr := attribute.String("string_key", "forty-two")

internal/test/e2e/otelglobal/traces.json

@@ -65,6 +65,15 @@
               "status": {},
               "traceId": "xxxxx"
             },
+            {
+              "attributes": [],
+              "kind": 3,
+              "name": "SetNameOverride",
+              "parentSpanId": "xxxxx",
+              "spanId": "xxxxx",
+              "status": {},
+              "traceId": "xxxxx"
+            },
             {
               "attributes": [
                 {

internal/test/e2e/otelglobal/verify.bats

@@ -59,6 +59,11 @@ SCOPE="go.opentelemetry.io/auto/go.opentelemetry.io/otel/internal/global"
   assert_regex "$parent_span_id" ${MATCH_A_SPAN_ID}
 }
 
+@test "server :: span set name overrides original span name" {
+  span_set_name_override=$(spans_from_scope_named ${SCOPE} | jq "select(.name == \"SetNameOverride\")" | jq ".traceId")
+  assert_regex "$trace_id" ${MATCH_A_TRACE_ID}
+}
+
 @test "server :: expected (redacted) trace output" {
   redact_json
   assert_equal "$(git --no-pager diff ${BATS_TEST_DIRNAME}/traces.json)" ""