Implement otlploggrpc exporter (#5582)

Part of #5056

It also abstracts some test help functions from the client and adjusts
the indent of `UploadLogs` and `PartialSuccess` in client tests.

For full usage of this exporter, check
#5522

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

exporters/otlp/otlplog/otlploggrpc/client.go

@@ -204,6 +204,16 @@ func (c *client) exportContext(parent context.Context) (context.Context, context
 	return ctx, cancel
 }
 
+type noopClient struct{}
+
+func newNoopClient() *noopClient {
+	return &noopClient{}
+}
+
+func (c *noopClient) UploadLogs(context.Context, []*logpb.ResourceLogs) error { return nil }
+
+func (c *noopClient) Shutdown(context.Context) error { return nil }
+
 // retryable returns if err identifies a request that can be retried and a
 // duration to wait for if an explicit throttle time is included in err.
 func retryable(err error) (bool, time.Duration) {

exporters/otlp/otlplog/otlploggrpc/client_test.go

@@ -450,113 +450,114 @@ func (c *grpcCollector) Collect() *storage {
 	return c.storage
 }
 
-func TestClient(t *testing.T) {
-	factory := func(rCh <-chan exportResult) (*client, *grpcCollector) {
-		coll, err := newGRPCCollector("", rCh)
-		require.NoError(t, err)
-
-		addr := coll.listener.Addr().String()
-		opts := []Option{WithEndpoint(addr), WithInsecure()}
-		cfg := newConfig(opts)
-		client, err := newClient(cfg)
-		require.NoError(t, err)
-		return client, coll
+func clientFactory(t *testing.T, rCh <-chan exportResult) (*client, *grpcCollector) {
+	t.Helper()
+	coll, err := newGRPCCollector("", rCh)
+	require.NoError(t, err)
+
+	addr := coll.listener.Addr().String()
+	opts := []Option{WithEndpoint(addr), WithInsecure()}
+	cfg := newConfig(opts)
+	client, err := newClient(cfg)
+	require.NoError(t, err)
+	return client, coll
+}
+
+func testCtxErrs(factory func() func(context.Context) error) func(t *testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+		ctx, cancel := context.WithCancel(context.Background())
+		t.Cleanup(cancel)
+
+		t.Run("DeadlineExceeded", func(t *testing.T) {
+			innerCtx, innerCancel := context.WithTimeout(ctx, time.Nanosecond)
+			t.Cleanup(innerCancel)
+			<-innerCtx.Done()
+
+			f := factory()
+			assert.ErrorIs(t, f(innerCtx), context.DeadlineExceeded)
+		})
+
+		t.Run("Canceled", func(t *testing.T) {
+			innerCtx, innerCancel := context.WithCancel(ctx)
+			innerCancel()
+
+			f := factory()
+			assert.ErrorIs(t, f(innerCtx), context.Canceled)
+		})
 	}
+}
 
+func TestClient(t *testing.T) {
 	t.Run("ClientHonorsContextErrors", func(t *testing.T) {
-		testCtxErrs := func(factory func() func(context.Context) error) func(t *testing.T) {
-			return func(t *testing.T) {
-				t.Helper()
-				ctx, cancel := context.WithCancel(context.Background())
-				t.Cleanup(cancel)
-
-				t.Run("DeadlineExceeded", func(t *testing.T) {
-					innerCtx, innerCancel := context.WithTimeout(ctx, time.Nanosecond)
-					t.Cleanup(innerCancel)
-					<-innerCtx.Done()
-
-					f := factory()
-					assert.ErrorIs(t, f(innerCtx), context.DeadlineExceeded)
-				})
-
-				t.Run("Canceled", func(t *testing.T) {
-					innerCtx, innerCancel := context.WithCancel(ctx)
-					innerCancel()
-
-					f := factory()
-					assert.ErrorIs(t, f(innerCtx), context.Canceled)
-				})
-			}
-		}
-
 		t.Run("Shutdown", testCtxErrs(func() func(context.Context) error {
-			c, _ := factory(nil)
+			c, _ := clientFactory(t, nil)
 			return c.Shutdown
 		}))
 
 		t.Run("UploadLog", testCtxErrs(func() func(context.Context) error {
-			c, _ := factory(nil)
+			c, _ := clientFactory(t, nil)
 			return func(ctx context.Context) error {
 				return c.UploadLogs(ctx, nil)
 			}
 		}))
+	})
 
-		t.Run("UploadLogs", func(t *testing.T) {
-			ctx := context.Background()
-			client, coll := factory(nil)
-
-			require.NoError(t, client.UploadLogs(ctx, resourceLogs))
-			require.NoError(t, client.Shutdown(ctx))
-			got := coll.Collect().Dump()
-			require.Len(t, got, 1, "upload of one ResourceLogs")
-			diff := cmp.Diff(got[0], resourceLogs[0], cmp.Comparer(proto.Equal))
-			if diff != "" {
-				t.Fatalf("unexpected ResourceLogs:\n%s", diff)
-			}
-		})
+	t.Run("UploadLogs", func(t *testing.T) {
+		ctx := context.Background()
+		client, coll := clientFactory(t, nil)
+
+		require.NoError(t, client.UploadLogs(ctx, resourceLogs))
+		require.NoError(t, client.Shutdown(ctx))
+		got := coll.Collect().Dump()
+		require.Len(t, got, 1, "upload of one ResourceLogs")
+		diff := cmp.Diff(got[0], resourceLogs[0], cmp.Comparer(proto.Equal))
+		if diff != "" {
+			t.Fatalf("unexpected ResourceLogs:\n%s", diff)
+		}
+	})
 
-		t.Run("PartialSuccess", func(t *testing.T) {
-			const n, msg = 2, "bad data"
-			rCh := make(chan exportResult, 3)
-			rCh <- exportResult{
-				Response: &collogpb.ExportLogsServiceResponse{
-					PartialSuccess: &collogpb.ExportLogsPartialSuccess{
-						RejectedLogRecords: n,
-						ErrorMessage:       msg,
-					},
+	t.Run("PartialSuccess", func(t *testing.T) {
+		const n, msg = 2, "bad data"
+		rCh := make(chan exportResult, 3)
+		rCh <- exportResult{
+			Response: &collogpb.ExportLogsServiceResponse{
+				PartialSuccess: &collogpb.ExportLogsPartialSuccess{
+					RejectedLogRecords: n,
+					ErrorMessage:       msg,
 				},
-			}
-			rCh <- exportResult{
-				Response: &collogpb.ExportLogsServiceResponse{
-					PartialSuccess: &collogpb.ExportLogsPartialSuccess{
-						// Should not be logged.
-						RejectedLogRecords: 0,
-						ErrorMessage:       "",
-					},
+			},
+		}
+		rCh <- exportResult{
+			Response: &collogpb.ExportLogsServiceResponse{
+				PartialSuccess: &collogpb.ExportLogsPartialSuccess{
+					// Should not be logged.
+					RejectedLogRecords: 0,
+					ErrorMessage:       "",
 				},
-			}
-			rCh <- exportResult{
-				Response: &collogpb.ExportLogsServiceResponse{},
-			}
+			},
+		}
+		rCh <- exportResult{
+			Response: &collogpb.ExportLogsServiceResponse{},
+		}
 
-			ctx := context.Background()
-			client, _ := factory(rCh)
+		ctx := context.Background()
+		client, _ := clientFactory(t, rCh)
 
-			defer func(orig otel.ErrorHandler) {
-				otel.SetErrorHandler(orig)
-			}(otel.GetErrorHandler())
+		defer func(orig otel.ErrorHandler) {
+			otel.SetErrorHandler(orig)
+		}(otel.GetErrorHandler())
 
-			var errs []error
-			eh := otel.ErrorHandlerFunc(func(e error) { errs = append(errs, e) })
-			otel.SetErrorHandler(eh)
+		var errs []error
+		eh := otel.ErrorHandlerFunc(func(e error) { errs = append(errs, e) })
+		otel.SetErrorHandler(eh)
 
-			require.NoError(t, client.UploadLogs(ctx, resourceLogs))
-			require.NoError(t, client.UploadLogs(ctx, resourceLogs))
-			require.NoError(t, client.UploadLogs(ctx, resourceLogs))
+		require.NoError(t, client.UploadLogs(ctx, resourceLogs))
+		require.NoError(t, client.UploadLogs(ctx, resourceLogs))
+		require.NoError(t, client.UploadLogs(ctx, resourceLogs))
 
-			require.Equal(t, 1, len(errs))
-			want := fmt.Sprintf("%s (%d log records rejected)", msg, n)
-			assert.ErrorContains(t, errs[0], want)
-		})
+		require.Equal(t, 1, len(errs))
+		want := fmt.Sprintf("%s (%d log records rejected)", msg, n)
+		assert.ErrorContains(t, errs[0], want)
 	})
 }

exporters/otlp/otlplog/otlploggrpc/exporter.go

@@ -5,14 +5,27 @@ package otlploggrpc // import "go.opentelemetry.io/otel/exporters/otlp/otlplog/o
 
 import (
 	"context"
+	"sync"
+	"sync/atomic"
 
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc/internal/transform"
 	"go.opentelemetry.io/otel/sdk/log"
+	logpb "go.opentelemetry.io/proto/otlp/logs/v1"
 )
 
+type logClient interface {
+	UploadLogs(ctx context.Context, rl []*logpb.ResourceLogs) error
+	Shutdown(context.Context) error
+}
+
 // Exporter is a OpenTelemetry log Exporter. It transports log data encoded as
 // OTLP protobufs using gRPC.
 type Exporter struct {
-	// TODO: implement.
+	// Ensure synchronous access to the client across all functionality.
+	clientMu sync.Mutex
+	client   logClient
+
+	stopped atomic.Bool
 }
 
 // Compile-time check Exporter implements [log.Exporter].
@@ -25,29 +38,52 @@ func New(_ context.Context, options ...Option) (*Exporter, error) {
 	if err != nil {
 		return nil, err
 	}
-	return newExporter(c, cfg)
+	return newExporter(c), nil
 }
 
-func newExporter(*client, config) (*Exporter, error) {
-	// TODO: implement
-	return &Exporter{}, nil
+func newExporter(c logClient) *Exporter {
+	var e Exporter
+	e.client = c
+	return &e
 }
 
+var transformResourceLogs = transform.ResourceLogs
+
 // Export transforms and transmits log records to an OTLP receiver.
+//
+// This method returns nil and drops records if called after Shutdown.
+// This method returns an error if the method is canceled by the passed context.
 func (e *Exporter) Export(ctx context.Context, records []log.Record) error {
-	// TODO: implement.
-	return nil
+	if e.stopped.Load() {
+		return nil
+	}
+
+	otlp := transformResourceLogs(records)
+	if otlp == nil {
+		return nil
+	}
+
+	e.clientMu.Lock()
+	defer e.clientMu.Unlock()
+	return e.client.UploadLogs(ctx, otlp)
 }
 
 // Shutdown shuts down the Exporter. Calls to Export or ForceFlush will perform
 // no operation after this is called.
 func (e *Exporter) Shutdown(ctx context.Context) error {
-	// TODO: implement.
-	return nil
+	if e.stopped.Swap(true) {
+		return nil
+	}
+
+	e.clientMu.Lock()
+	defer e.clientMu.Unlock()
+
+	err := e.client.Shutdown(ctx)
+	e.client = newNoopClient()
+	return err
 }
 
 // ForceFlush does nothing. The Exporter holds no state.
 func (e *Exporter) ForceFlush(ctx context.Context) error {
-	// TODO: implement.
 	return nil
 }