feat: initial tracing support (#1623)

1 files changed, 432 insertions, 0 deletions

diff --git a/vendor/go.opentelemetry.io/otel/sdk/trace/batch_span_processor.go b/vendor/go.opentelemetry.io/otel/sdk/trace/batch_span_processor.go
new file mode 100644
index 000000000..a2d7db490
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/sdk/trace/batch_span_processor.go
@@ -0,0 +1,432 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"context"
+	"runtime"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/internal/global"
+	"go.opentelemetry.io/otel/sdk/internal/env"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Defaults for BatchSpanProcessorOptions.
+const (
+	DefaultMaxQueueSize       = 2048
+	DefaultScheduleDelay      = 5000
+	DefaultExportTimeout      = 30000
+	DefaultMaxExportBatchSize = 512
+)
+
+// BatchSpanProcessorOption configures a BatchSpanProcessor.
+type BatchSpanProcessorOption func(o *BatchSpanProcessorOptions)
+
+// BatchSpanProcessorOptions is configuration settings for a
+// BatchSpanProcessor.
+type BatchSpanProcessorOptions struct {
+	// MaxQueueSize is the maximum queue size to buffer spans for delayed processing. If the
+	// queue gets full it drops the spans. Use BlockOnQueueFull to change this behavior.
+	// The default value of MaxQueueSize is 2048.
+	MaxQueueSize int
+
+	// BatchTimeout is the maximum duration for constructing a batch. Processor
+	// forcefully sends available spans when timeout is reached.
+	// The default value of BatchTimeout is 5000 msec.
+	BatchTimeout time.Duration
+
+	// ExportTimeout specifies the maximum duration for exporting spans. If the timeout
+	// is reached, the export will be cancelled.
+	// The default value of ExportTimeout is 30000 msec.
+	ExportTimeout time.Duration
+
+	// MaxExportBatchSize is the maximum number of spans to process in a single batch.
+	// If there are more than one batch worth of spans then it processes multiple batches
+	// of spans one batch after the other without any delay.
+	// The default value of MaxExportBatchSize is 512.
+	MaxExportBatchSize int
+
+	// BlockOnQueueFull blocks onEnd() and onStart() method if the queue is full
+	// AND if BlockOnQueueFull is set to true.
+	// Blocking option should be used carefully as it can severely affect the performance of an
+	// application.
+	BlockOnQueueFull bool
+}
+
+// batchSpanProcessor is a SpanProcessor that batches asynchronously-received
+// spans and sends them to a trace.Exporter when complete.
+type batchSpanProcessor struct {
+	e SpanExporter
+	o BatchSpanProcessorOptions
+
+	queue   chan ReadOnlySpan
+	dropped uint32
+
+	batch      []ReadOnlySpan
+	batchMutex sync.Mutex
+	timer      *time.Timer
+	stopWait   sync.WaitGroup
+	stopOnce   sync.Once
+	stopCh     chan struct{}
+}
+
+var _ SpanProcessor = (*batchSpanProcessor)(nil)
+
+// NewBatchSpanProcessor creates a new SpanProcessor that will send completed
+// span batches to the exporter with the supplied options.
+//
+// If the exporter is nil, the span processor will preform no action.
+func NewBatchSpanProcessor(exporter SpanExporter, options ...BatchSpanProcessorOption) SpanProcessor {
+	maxQueueSize := env.BatchSpanProcessorMaxQueueSize(DefaultMaxQueueSize)
+	maxExportBatchSize := env.BatchSpanProcessorMaxExportBatchSize(DefaultMaxExportBatchSize)
+
+	if maxExportBatchSize > maxQueueSize {
+		if DefaultMaxExportBatchSize > maxQueueSize {
+			maxExportBatchSize = maxQueueSize
+		} else {
+			maxExportBatchSize = DefaultMaxExportBatchSize
+		}
+	}
+
+	o := BatchSpanProcessorOptions{
+		BatchTimeout:       time.Duration(env.BatchSpanProcessorScheduleDelay(DefaultScheduleDelay)) * time.Millisecond,
+		ExportTimeout:      time.Duration(env.BatchSpanProcessorExportTimeout(DefaultExportTimeout)) * time.Millisecond,
+		MaxQueueSize:       maxQueueSize,
+		MaxExportBatchSize: maxExportBatchSize,
+	}
+	for _, opt := range options {
+		opt(&o)
+	}
+	bsp := &batchSpanProcessor{
+		e:      exporter,
+		o:      o,
+		batch:  make([]ReadOnlySpan, 0, o.MaxExportBatchSize),
+		timer:  time.NewTimer(o.BatchTimeout),
+		queue:  make(chan ReadOnlySpan, o.MaxQueueSize),
+		stopCh: make(chan struct{}),
+	}
+
+	bsp.stopWait.Add(1)
+	go func() {
+		defer bsp.stopWait.Done()
+		bsp.processQueue()
+		bsp.drainQueue()
+	}()
+
+	return bsp
+}
+
+// OnStart method does nothing.
+func (bsp *batchSpanProcessor) OnStart(parent context.Context, s ReadWriteSpan) {}
+
+// OnEnd method enqueues a ReadOnlySpan for later processing.
+func (bsp *batchSpanProcessor) OnEnd(s ReadOnlySpan) {
+	// Do not enqueue spans if we are just going to drop them.
+	if bsp.e == nil {
+		return
+	}
+	bsp.enqueue(s)
+}
+
+// Shutdown flushes the queue and waits until all spans are processed.
+// It only executes once. Subsequent call does nothing.
+func (bsp *batchSpanProcessor) Shutdown(ctx context.Context) error {
+	var err error
+	bsp.stopOnce.Do(func() {
+		wait := make(chan struct{})
+		go func() {
+			close(bsp.stopCh)
+			bsp.stopWait.Wait()
+			if bsp.e != nil {
+				if err := bsp.e.Shutdown(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+			close(wait)
+		}()
+		// Wait until the wait group is done or the context is cancelled
+		select {
+		case <-wait:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+	})
+	return err
+}
+
+type forceFlushSpan struct {
+	ReadOnlySpan
+	flushed chan struct{}
+}
+
+func (f forceFlushSpan) SpanContext() trace.SpanContext {
+	return trace.NewSpanContext(trace.SpanContextConfig{TraceFlags: trace.FlagsSampled})
+}
+
+// ForceFlush exports all ended spans that have not yet been exported.
+func (bsp *batchSpanProcessor) ForceFlush(ctx context.Context) error {
+	var err error
+	if bsp.e != nil {
+		flushCh := make(chan struct{})
+		if bsp.enqueueBlockOnQueueFull(ctx, forceFlushSpan{flushed: flushCh}) {
+			select {
+			case <-flushCh:
+				// Processed any items in queue prior to ForceFlush being called
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+
+		wait := make(chan error)
+		go func() {
+			wait <- bsp.exportSpans(ctx)
+			close(wait)
+		}()
+		// Wait until the export is finished or the context is cancelled/timed out
+		select {
+		case err = <-wait:
+		case <-ctx.Done():
+			err = ctx.Err()
+		}
+	}
+	return err
+}
+
+// WithMaxQueueSize returns a BatchSpanProcessorOption that configures the
+// maximum queue size allowed for a BatchSpanProcessor.
+func WithMaxQueueSize(size int) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.MaxQueueSize = size
+	}
+}
+
+// WithMaxExportBatchSize returns a BatchSpanProcessorOption that configures
+// the maximum export batch size allowed for a BatchSpanProcessor.
+func WithMaxExportBatchSize(size int) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.MaxExportBatchSize = size
+	}
+}
+
+// WithBatchTimeout returns a BatchSpanProcessorOption that configures the
+// maximum delay allowed for a BatchSpanProcessor before it will export any
+// held span (whether the queue is full or not).
+func WithBatchTimeout(delay time.Duration) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.BatchTimeout = delay
+	}
+}
+
+// WithExportTimeout returns a BatchSpanProcessorOption that configures the
+// amount of time a BatchSpanProcessor waits for an exporter to export before
+// abandoning the export.
+func WithExportTimeout(timeout time.Duration) BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.ExportTimeout = timeout
+	}
+}
+
+// WithBlocking returns a BatchSpanProcessorOption that configures a
+// BatchSpanProcessor to wait for enqueue operations to succeed instead of
+// dropping data when the queue is full.
+func WithBlocking() BatchSpanProcessorOption {
+	return func(o *BatchSpanProcessorOptions) {
+		o.BlockOnQueueFull = true
+	}
+}
+
+// exportSpans is a subroutine of processing and draining the queue.
+func (bsp *batchSpanProcessor) exportSpans(ctx context.Context) error {
+	bsp.timer.Reset(bsp.o.BatchTimeout)
+
+	bsp.batchMutex.Lock()
+	defer bsp.batchMutex.Unlock()
+
+	if bsp.o.ExportTimeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, bsp.o.ExportTimeout)
+		defer cancel()
+	}
+
+	if l := len(bsp.batch); l > 0 {
+		global.Debug("exporting spans", "count", len(bsp.batch), "total_dropped", atomic.LoadUint32(&bsp.dropped))
+		err := bsp.e.ExportSpans(ctx, bsp.batch)
+
+		// A new batch is always created after exporting, even if the batch failed to be exported.
+		//
+		// It is up to the exporter to implement any type of retry logic if a batch is failing
+		// to be exported, since it is specific to the protocol and backend being sent to.
+		bsp.batch = bsp.batch[:0]
+
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// processQueue removes spans from the `queue` channel until processor
+// is shut down. It calls the exporter in batches of up to MaxExportBatchSize
+// waiting up to BatchTimeout to form a batch.
+func (bsp *batchSpanProcessor) processQueue() {
+	defer bsp.timer.Stop()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	for {
+		select {
+		case <-bsp.stopCh:
+			return
+		case <-bsp.timer.C:
+			if err := bsp.exportSpans(ctx); err != nil {
+				otel.Handle(err)
+			}
+		case sd := <-bsp.queue:
+			if ffs, ok := sd.(forceFlushSpan); ok {
+				close(ffs.flushed)
+				continue
+			}
+			bsp.batchMutex.Lock()
+			bsp.batch = append(bsp.batch, sd)
+			shouldExport := len(bsp.batch) >= bsp.o.MaxExportBatchSize
+			bsp.batchMutex.Unlock()
+			if shouldExport {
+				if !bsp.timer.Stop() {
+					<-bsp.timer.C
+				}
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+		}
+	}
+}
+
+// drainQueue awaits the any caller that had added to bsp.stopWait
+// to finish the enqueue, then exports the final batch.
+func (bsp *batchSpanProcessor) drainQueue() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	for {
+		select {
+		case sd := <-bsp.queue:
+			if sd == nil {
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+				return
+			}
+
+			bsp.batchMutex.Lock()
+			bsp.batch = append(bsp.batch, sd)
+			shouldExport := len(bsp.batch) == bsp.o.MaxExportBatchSize
+			bsp.batchMutex.Unlock()
+
+			if shouldExport {
+				if err := bsp.exportSpans(ctx); err != nil {
+					otel.Handle(err)
+				}
+			}
+		default:
+			close(bsp.queue)
+		}
+	}
+}
+
+func (bsp *batchSpanProcessor) enqueue(sd ReadOnlySpan) {
+	ctx := context.TODO()
+	if bsp.o.BlockOnQueueFull {
+		bsp.enqueueBlockOnQueueFull(ctx, sd)
+	} else {
+		bsp.enqueueDrop(ctx, sd)
+	}
+}
+
+func recoverSendOnClosedChan() {
+	x := recover()
+	switch err := x.(type) {
+	case nil:
+		return
+	case runtime.Error:
+		if err.Error() == "send on closed channel" {
+			return
+		}
+	}
+	panic(x)
+}
+
+func (bsp *batchSpanProcessor) enqueueBlockOnQueueFull(ctx context.Context, sd ReadOnlySpan) bool {
+	if !sd.SpanContext().IsSampled() {
+		return false
+	}
+
+	// This ensures the bsp.queue<- below does not panic as the
+	// processor shuts down.
+	defer recoverSendOnClosedChan()
+
+	select {
+	case <-bsp.stopCh:
+		return false
+	default:
+	}
+
+	select {
+	case bsp.queue <- sd:
+		return true
+	case <-ctx.Done():
+		return false
+	}
+}
+
+func (bsp *batchSpanProcessor) enqueueDrop(ctx context.Context, sd ReadOnlySpan) bool {
+	if !sd.SpanContext().IsSampled() {
+		return false
+	}
+
+	// This ensures the bsp.queue<- below does not panic as the
+	// processor shuts down.
+	defer recoverSendOnClosedChan()
+
+	select {
+	case <-bsp.stopCh:
+		return false
+	default:
+	}
+
+	select {
+	case bsp.queue <- sd:
+		return true
+	default:
+		atomic.AddUint32(&bsp.dropped, 1)
+	}
+	return false
+}
+
+// MarshalLog is the marshaling function used by the logging system to represent this exporter.
+func (bsp *batchSpanProcessor) MarshalLog() interface{} {
+	return struct {
+		Type         string
+		SpanExporter SpanExporter
+		Config       BatchSpanProcessorOptions
+	}{
+		Type:         "BatchSpanProcessor",
+		SpanExporter: bsp.e,
+		Config:       bsp.o,
+	}
+}