fix: cannot lazily link against GLS accessors

.github/workflows/tests.yml

@@ -100,6 +100,18 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: '>=3.9 <3.13'
+      - name: Run Integration Tests
+        shell: bash # PowerShell has different syntax for env. var access...
+        run: |-
+          # Without orchestrion enabled
+          go -C _integration-tests test -v ./...
+
+          # With orchestrion enabled
+          mkdir -p ${GOCOVERDIR}
+          go run -cover -covermode=atomic -coverpkg=./... . go -C _integration-tests test -v ./...
+        env:
+          GOCOVERDIR: ${{ github.workspace }}/coverage/raw
+          GOCACHE: ${{ runner.temp }}/gocache
       - name: Run Integration Tests
         run: ./integration-tests.ps1
         env:
@@ -109,7 +121,7 @@ jobs:
         shell: bash # PowerShell mkdir -p fails if the directory already exists...
         run: |-
           mkdir -p ./coverage
-          go tool covdata textfmt -i ./_integration-tests/outputs/coverage -o ./coverage/integration.out
+          go tool covdata textfmt -i ./coverage/raw,./_integration-tests/outputs/coverage -o ./coverage/integration.out
       - name: Determine simple go version
         if: always() && github.event_name != 'merge_group'
         id: simple-go-version

_integration-tests/gls/access.go

@@ -0,0 +1,45 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2023-present Datadog, Inc.
+
+package gls
+
+/*
+extern void cgoCallback();
+*/
+import "C"
+
+import (
+	_ "runtime" // Provides go:linkname targets (if Orchestrion modifies)
+	_ "unsafe"  // For go:linkname
+)
+
+var (
+	//go:linkname __dd_orchestrion_gls_get __dd_orchestrion_gls_get
+	__dd_orchestrion_gls_get func() any
+
+	//go:linkname __dd_orchestrion_gls_set __dd_orchestrion_gls_set
+	__dd_orchestrion_gls_set func(any)
+
+	get = func() any { return nil }
+	set = func(any) {}
+)
+
+func init() {
+	if __dd_orchestrion_gls_get != nil {
+		get = __dd_orchestrion_gls_get
+	}
+	if __dd_orchestrion_gls_set != nil {
+		set = __dd_orchestrion_gls_set
+	}
+}
+
+//export cgoCallback
+func cgoCallback() {
+	set("I am inside a cgo callback")
+}
+
+func cgoCall() {
+	C.cgoCallback()
+}

_integration-tests/gls/access_test.go

@@ -0,0 +1,121 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2023-present Datadog, Inc.
+
+package gls
+
+import (
+	"os"
+	"os/signal"
+	"runtime"
+	"sync"
+	"syscall"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+//dd:orchestrion-enabled
+const orchestrionEnabled = false
+
+func TestSimple(t *testing.T) {
+	expected := "Hello, World!"
+
+	set(expected)
+	actual := get()
+
+	if orchestrionEnabled {
+		t.Log("Orchestrion IS enabled")
+		require.Equal(t, expected, actual)
+	} else {
+		t.Log("Orchestrion IS NOT enabled")
+		require.Nil(t, actual)
+	}
+}
+
+// TestCGO tests that the GLS is correctly set even when the code comes from a cgo callback.
+func TestCGO(t *testing.T) {
+	if !orchestrionEnabled {
+		t.Skip("Orchestrion is not enabled")
+	}
+
+	expected := "I am inside a cgo callback"
+	set(nil)
+	cgoCall()
+	require.Equal(t, expected, get())
+}
+
+// TestSignal tests that the GLS is correctly set even when the code comes from a signal handler.
+func TestSignal(t *testing.T) {
+	if !orchestrionEnabled {
+		t.Skip("Orchestrion is not enabled")
+	}
+
+	expected := "I am inside a signal handler"
+
+	set(nil)
+
+	doneSigChan := make(chan struct{}, 1)
+	checkChan := make(chan struct{}, 1)
+	doneCheckChan := make(chan struct{}, 1)
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGUSR1)
+
+	go func() {
+		<-sigChan
+		set(expected)
+		doneSigChan <- struct{}{}
+
+		<-checkChan
+		require.Equal(t, expected, get())
+		doneCheckChan <- struct{}{}
+	}()
+
+	syscall.Kill(syscall.Getpid(), syscall.SIGUSR1)
+	<-doneSigChan
+	checkChan <- struct{}{}
+	<-doneCheckChan
+}
+
+func TestConcurrency(t *testing.T) {
+	if !orchestrionEnabled {
+		t.Skip("Orchestrion is not enabled")
+	}
+
+	nbSets := 5000
+	nbGoRoutines := 300
+
+	var wg sync.WaitGroup
+
+	wg.Add(nbGoRoutines)
+	for i := 0; i < nbGoRoutines; i++ {
+		go func() {
+			defer wg.Done()
+			for j := 0; j < nbSets; j++ {
+				set(j)
+				require.Equal(t, j, get())
+			}
+		}()
+	}
+
+	wg.Wait()
+}
+
+func BenchmarkGLS(b *testing.B) {
+	if !orchestrionEnabled {
+		b.Skip("Orchestrion is not enabled")
+	}
+
+	b.Run("Set", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			set(i)
+		}
+	})
+
+	b.Run("Get", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			runtime.KeepAlive(get())
+		}
+	})
+}

internal/injector/builtin/yaml/stdlib/runtime.yml

@@ -23,13 +23,14 @@ aspects:
           type: any
       - add-blank-import: unsafe # Needed for go:linkname
       - inject-declarations:
+          # Reference: https://github.com/golang/go/blob/6d89b38ed86e0bfa0ddaba08dc4071e6bb300eea/src/runtime/HACKING.md?plain=1#L44-L54
           template: |-
             //go:linkname __dd_orchestrion_gls_get __dd_orchestrion_gls_get
-            func __dd_orchestrion_gls_get() any {
+            var __dd_orchestrion_gls_get = func() any {
               return getg().m.curg.__dd_gls
             }
 
             //go:linkname __dd_orchestrion_gls_set __dd_orchestrion_gls_set
-            func __dd_orchestrion_gls_set(val any) {
+            var __dd_orchestrion_gls_set = func(val any) {
               getg().m.curg.__dd_gls = val
             }