Merge pull request #1692 from sjug/opentracing_clean

OpenTracing First Impl

10 files changed, 638 insertions, 0 deletions

diff --git a/vendor/github.com/uber/jaeger-lib/LICENSE b/vendor/github.com/uber/jaeger-lib/LICENSE
new file mode 100644
index 000000000..261eeb9e9
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/LICENSE
@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   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.
diff --git a/vendor/github.com/uber/jaeger-lib/README.md b/vendor/github.com/uber/jaeger-lib/README.md
new file mode 100644
index 000000000..144ed1fb8
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/README.md
@@ -0,0 +1,27 @@
+[![GoDoc][doc-img]][doc] [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov]
+
+
+# jaeger-lib
+
+A collection of shared infrastructure libraries used by different
+components of [Jaeger](https://github.com/uber/jaeger) backend and [jaeger-client-go](https://github.com/uber/jaeger-client-go).
+This library is *not intended to be used standalone*, and provides *no guarantees of backwards compatibility*.
+
+The library's import path is `github.com/uber/jaeger-lib`.
+
+## How to Contribute
+
+Please see [CONTRIBUTING.md](CONTRIBUTING.md).
+
+## License
+  
+[Apache 2.0 License](./LICENSE).
+
+
+[doc-img]: https://godoc.org/github.com/uber/jaeger-lib?status.svg
+[doc]: https://godoc.org/github.com/uber/jaeger-lib
+[ci-img]: https://travis-ci.org/jaegertracing/jaeger-lib.svg?branch=master
+[ci]: https://travis-ci.org/jaegertracing/jaeger-lib
+[cov-img]: https://coveralls.io/repos/jaegertracing/jaeger-lib/badge.svg?branch=master&service=github
+[cov]: https://coveralls.io/github/jaegertracing/jaeger-lib?branch=master
+
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/counter.go b/vendor/github.com/uber/jaeger-lib/metrics/counter.go
new file mode 100644
index 000000000..2a6a43efd
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/counter.go
@@ -0,0 +1,28 @@
+// 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 metrics
+
+// Counter tracks the number of times an event has occurred
+type Counter interface {
+	// Inc adds the given value to the counter.
+	Inc(int64)
+}
+
+// NullCounter counter that does nothing
+var NullCounter Counter = nullCounter{}
+
+type nullCounter struct{}
+
+func (nullCounter) Inc(int64) {}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/factory.go b/vendor/github.com/uber/jaeger-lib/metrics/factory.go
new file mode 100644
index 000000000..0ead061eb
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/factory.go
@@ -0,0 +1,78 @@
+// 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 metrics
+
+import (
+	"time"
+)
+
+// NSOptions defines the name and tags map associated with a factory namespace
+type NSOptions struct {
+	Name string
+	Tags map[string]string
+}
+
+// Options defines the information associated with a metric
+type Options struct {
+	Name string
+	Tags map[string]string
+	Help string
+}
+
+// TimerOptions defines the information associated with a metric
+type TimerOptions struct {
+	Name    string
+	Tags    map[string]string
+	Help    string
+	Buckets []time.Duration
+}
+
+// HistogramOptions defines the information associated with a metric
+type HistogramOptions struct {
+	Name    string
+	Tags    map[string]string
+	Help    string
+	Buckets []float64
+}
+
+// Factory creates new metrics
+type Factory interface {
+	Counter(metric Options) Counter
+	Timer(metric TimerOptions) Timer
+	Gauge(metric Options) Gauge
+	Histogram(metric HistogramOptions) Histogram
+
+	// Namespace returns a nested metrics factory.
+	Namespace(scope NSOptions) Factory
+}
+
+// NullFactory is a metrics factory that returns NullCounter, NullTimer, and NullGauge.
+var NullFactory Factory = nullFactory{}
+
+type nullFactory struct{}
+
+func (nullFactory) Counter(options Options) Counter {
+	return NullCounter
+}
+func (nullFactory) Timer(options TimerOptions) Timer {
+	return NullTimer
+}
+func (nullFactory) Gauge(options Options) Gauge {
+	return NullGauge
+}
+func (nullFactory) Histogram(options HistogramOptions) Histogram {
+	return NullHistogram
+}
+func (nullFactory) Namespace(scope NSOptions) Factory { return NullFactory }
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/gauge.go b/vendor/github.com/uber/jaeger-lib/metrics/gauge.go
new file mode 100644
index 000000000..3c606391a
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/gauge.go
@@ -0,0 +1,28 @@
+// 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 metrics
+
+// Gauge returns instantaneous measurements of something as an int64 value
+type Gauge interface {
+	// Update the gauge to the value passed in.
+	Update(int64)
+}
+
+// NullGauge gauge that does nothing
+var NullGauge Gauge = nullGauge{}
+
+type nullGauge struct{}
+
+func (nullGauge) Update(int64) {}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/histogram.go b/vendor/github.com/uber/jaeger-lib/metrics/histogram.go
new file mode 100644
index 000000000..d3bd6174f
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/histogram.go
@@ -0,0 +1,28 @@
+// Copyright (c) 2018 The Jaeger 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 metrics
+
+// Histogram that keeps track of a distribution of values.
+type Histogram interface {
+	// Records the value passed in.
+	Record(float64)
+}
+
+// NullHistogram that does nothing
+var NullHistogram Histogram = nullHistogram{}
+
+type nullHistogram struct{}
+
+func (nullHistogram) Record(float64) {}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/keys.go b/vendor/github.com/uber/jaeger-lib/metrics/keys.go
new file mode 100644
index 000000000..c24445a10
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/keys.go
@@ -0,0 +1,35 @@
+// 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 metrics
+
+import (
+	"sort"
+)
+
+// GetKey converts name+tags into a single string of the form
+// "name|tag1=value1|...|tagN=valueN", where tag names are
+// sorted alphabetically.
+func GetKey(name string, tags map[string]string, tagsSep string, tagKVSep string) string {
+	keys := make([]string, 0, len(tags))
+	for k := range tags {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	key := name
+	for _, k := range keys {
+		key = key + tagsSep + k + tagKVSep + tags[k]
+	}
+	return key
+}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/metrics.go b/vendor/github.com/uber/jaeger-lib/metrics/metrics.go
new file mode 100644
index 000000000..0c6396888
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/metrics.go
@@ -0,0 +1,137 @@
+// 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 metrics
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// MustInit initializes the passed in metrics and initializes its fields using the passed in factory.
+//
+// It uses reflection to initialize a struct containing metrics fields
+// by assigning new Counter/Gauge/Timer values with the metric name retrieved
+// from the `metric` tag and stats tags retrieved from the `tags` tag.
+//
+// Note: all fields of the struct must be exported, have a `metric` tag, and be
+// of type Counter or Gauge or Timer.
+//
+// Errors during Init lead to a panic.
+func MustInit(metrics interface{}, factory Factory, globalTags map[string]string) {
+	if err := Init(metrics, factory, globalTags); err != nil {
+		panic(err.Error())
+	}
+}
+
+// Init does the same as Init, but returns an error instead of
+// panicking.
+func Init(m interface{}, factory Factory, globalTags map[string]string) error {
+	// Allow user to opt out of reporting metrics by passing in nil.
+	if factory == nil {
+		factory = NullFactory
+	}
+
+	counterPtrType := reflect.TypeOf((*Counter)(nil)).Elem()
+	gaugePtrType := reflect.TypeOf((*Gauge)(nil)).Elem()
+	timerPtrType := reflect.TypeOf((*Timer)(nil)).Elem()
+	histogramPtrType := reflect.TypeOf((*Histogram)(nil)).Elem()
+
+	v := reflect.ValueOf(m).Elem()
+	t := v.Type()
+	for i := 0; i < t.NumField(); i++ {
+		tags := make(map[string]string)
+		for k, v := range globalTags {
+			tags[k] = v
+		}
+		var buckets []float64
+		field := t.Field(i)
+		metric := field.Tag.Get("metric")
+		if metric == "" {
+			return fmt.Errorf("Field %s is missing a tag 'metric'", field.Name)
+		}
+		if tagString := field.Tag.Get("tags"); tagString != "" {
+			tagPairs := strings.Split(tagString, ",")
+			for _, tagPair := range tagPairs {
+				tag := strings.Split(tagPair, "=")
+				if len(tag) != 2 {
+					return fmt.Errorf(
+						"Field [%s]: Tag [%s] is not of the form key=value in 'tags' string [%s]",
+						field.Name, tagPair, tagString)
+				}
+				tags[tag[0]] = tag[1]
+			}
+		}
+		if bucketString := field.Tag.Get("buckets"); bucketString != "" {
+			if field.Type.AssignableTo(timerPtrType) {
+				// TODO: Parse timer duration buckets
+				return fmt.Errorf(
+					"Field [%s]: Buckets are not currently initialized for timer metrics",
+					field.Name)
+			} else if field.Type.AssignableTo(histogramPtrType) {
+				bucketValues := strings.Split(bucketString, ",")
+				for _, bucket := range bucketValues {
+					b, err := strconv.ParseFloat(bucket, 64)
+					if err != nil {
+						return fmt.Errorf(
+							"Field [%s]: Bucket [%s] could not be converted to float64 in 'buckets' string [%s]",
+							field.Name, bucket, bucketString)
+					}
+					buckets = append(buckets, b)
+				}
+			} else {
+				return fmt.Errorf(
+					"Field [%s]: Buckets should only be defined for Timer and Histogram metric types",
+					field.Name)
+			}
+		}
+		help := field.Tag.Get("help")
+		var obj interface{}
+		if field.Type.AssignableTo(counterPtrType) {
+			obj = factory.Counter(Options{
+				Name: metric,
+				Tags: tags,
+				Help: help,
+			})
+		} else if field.Type.AssignableTo(gaugePtrType) {
+			obj = factory.Gauge(Options{
+				Name: metric,
+				Tags: tags,
+				Help: help,
+			})
+		} else if field.Type.AssignableTo(timerPtrType) {
+			// TODO: Add buckets once parsed (see TODO above)
+			obj = factory.Timer(TimerOptions{
+				Name: metric,
+				Tags: tags,
+				Help: help,
+			})
+		} else if field.Type.AssignableTo(histogramPtrType) {
+			obj = factory.Histogram(HistogramOptions{
+				Name:    metric,
+				Tags:    tags,
+				Help:    help,
+				Buckets: buckets,
+			})
+		} else {
+			return fmt.Errorf(
+				"Field %s is not a pointer to timer, gauge, or counter",
+				field.Name)
+		}
+		v.Field(i).Set(reflect.ValueOf(obj))
+	}
+	return nil
+}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/stopwatch.go b/vendor/github.com/uber/jaeger-lib/metrics/stopwatch.go
new file mode 100644
index 000000000..4a8abdb53
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/stopwatch.go
@@ -0,0 +1,43 @@
+// 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 metrics
+
+import (
+	"time"
+)
+
+// StartStopwatch begins recording the executing time of an event, returning
+// a Stopwatch that should be used to stop the recording the time for
+// that event.  Multiple events can be occurring simultaneously each
+// represented by different active Stopwatches
+func StartStopwatch(timer Timer) Stopwatch {
+	return Stopwatch{t: timer, start: time.Now()}
+}
+
+// A Stopwatch tracks the execution time of a specific event
+type Stopwatch struct {
+	t     Timer
+	start time.Time
+}
+
+// Stop stops executing of the stopwatch and records the amount of elapsed time
+func (s Stopwatch) Stop() {
+	s.t.Record(s.ElapsedTime())
+}
+
+// ElapsedTime returns the amount of elapsed time (in time.Duration)
+func (s Stopwatch) ElapsedTime() time.Duration {
+	return time.Since(s.start)
+}
diff --git a/vendor/github.com/uber/jaeger-lib/metrics/timer.go b/vendor/github.com/uber/jaeger-lib/metrics/timer.go
new file mode 100644
index 000000000..e18d222ab
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-lib/metrics/timer.go
@@ -0,0 +1,33 @@
+// 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 metrics
+
+import (
+	"time"
+)
+
+// Timer accumulates observations about how long some operation took,
+// and also maintains a historgam of percentiles.
+type Timer interface {
+	// Records the time passed in.
+	Record(time.Duration)
+}
+
+// NullTimer timer that does nothing
+var NullTimer Timer = nullTimer{}
+
+type nullTimer struct{}
+
+func (nullTimer) Record(time.Duration) {}