swarm: integrate OpenTracing; propagate ctx to internal APIs (#17169)

* swarm: propagate ctx, enable opentracing

* swarm/tracing: log error when tracing is misconfigured

vendor/github.com/uber/jaeger-client-go/reporter_options.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// 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 jaeger
+
+import (
+	"time"
+)
+
+// ReporterOption is a function that sets some option on the reporter.
+type ReporterOption func(c *reporterOptions)
+
+// ReporterOptions is a factory for all available ReporterOption's
+var ReporterOptions reporterOptions
+
+// reporterOptions control behavior of the reporter.
+type reporterOptions struct {
+	// queueSize is the size of internal queue where reported spans are stored before they are processed in the background
+	queueSize int
+	// bufferFlushInterval is how often the buffer is force-flushed, even if it's not full
+	bufferFlushInterval time.Duration
+	// logger is used to log errors of span submissions
+	logger Logger
+	// metrics is used to record runtime stats
+	metrics *Metrics
+}
+
+// QueueSize creates a ReporterOption that sets the size of the internal queue where
+// spans are stored before they are processed.
+func (reporterOptions) QueueSize(queueSize int) ReporterOption {
+	return func(r *reporterOptions) {
+		r.queueSize = queueSize
+	}
+}
+
+// Metrics creates a ReporterOption that initializes Metrics in the reporter,
+// which is used to record runtime statistics.
+func (reporterOptions) Metrics(metrics *Metrics) ReporterOption {
+	return func(r *reporterOptions) {
+		r.metrics = metrics
+	}
+}
+
+// BufferFlushInterval creates a ReporterOption that sets how often the queue
+// is force-flushed.
+func (reporterOptions) BufferFlushInterval(bufferFlushInterval time.Duration) ReporterOption {
+	return func(r *reporterOptions) {
+		r.bufferFlushInterval = bufferFlushInterval
+	}
+}
+
+// Logger creates a ReporterOption that initializes the logger used to log
+// errors of span submissions.
+func (reporterOptions) Logger(logger Logger) ReporterOption {
+	return func(r *reporterOptions) {
+		r.logger = logger
+	}
+}