specialize simplelru(span's lruMap) for attributes only

example/basic/go.sum

@@ -90,8 +90,6 @@ github.com/gostaticanalysis/analysisutil v0.0.3/go.mod h1:eEOZF4jCKGi+aprrirO9e7
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

example/http-stackdriver/go.sum

@@ -117,9 +117,8 @@ github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmg
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hashicorp/golang-lru v0.5.1 h1:0hERBMJE1eitiLkihrMvRVBYAkpHzc/J3QdDN+dAcgU=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

example/http/go.sum

@@ -91,8 +91,6 @@ github.com/gostaticanalysis/analysisutil v0.0.3/go.mod h1:eEOZF4jCKGi+aprrirO9e7
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=

example/jaeger/go.sum

@@ -102,8 +102,6 @@ github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgf
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

example/namedtracer/go.sum

@@ -90,8 +90,6 @@ github.com/gostaticanalysis/analysisutil v0.0.3/go.mod h1:eEOZF4jCKGi+aprrirO9e7
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

exporter/trace/jaeger/go.sum

@@ -104,8 +104,6 @@ github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgf
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

exporter/trace/stackdriver/go.sum

@@ -116,9 +116,8 @@ github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmg
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hashicorp/golang-lru v0.5.1 h1:0hERBMJE1eitiLkihrMvRVBYAkpHzc/J3QdDN+dAcgU=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=

go.mod

@@ -12,7 +12,6 @@ require (
 	github.com/google/go-cmp v0.3.1
 	github.com/google/gofuzz v1.0.0 // indirect
 	github.com/gostaticanalysis/analysisutil v0.0.3 // indirect
-	github.com/hashicorp/golang-lru v0.5.3
 	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
 	github.com/magiconair/properties v1.8.1 // indirect
 	github.com/mattn/go-isatty v0.0.10 // indirect

go.sum

@@ -130,8 +130,6 @@ github.com/gostaticanalysis/analysisutil v0.0.3/go.mod h1:eEOZF4jCKGi+aprrirO9e7
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
-github.com/hashicorp/golang-lru v0.5.3 h1:YPkqC67at8FYaadspW/6uE0COsBxS2656RLEr8Bppgk=
-github.com/hashicorp/golang-lru v0.5.3/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
 github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=

sdk/trace/attributesMap.go

@@ -0,0 +1,90 @@
+// Copyright 2019, 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 (
+	"container/list"
+
+	"go.opentelemetry.io/otel/api/core"
+	"go.opentelemetry.io/otel/sdk/export/trace"
+)
+
+// attributesMap is a capped map of attributes, holding the most recent attributes.
+// Eviction is done via a LRU method, the oldest entry is removed to create room for a new entry.
+// Updates are allowed and refreshes the usage of the key.
+//
+// This is based from https://github.com/hashicorp/golang-lru/blob/master/simplelru/lru.go
+// With a subset of the its operations and specific for holding core.KeyValue
+type attributesMap struct {
+	attributes   map[core.Key]*list.Element
+	evictList    *list.List
+	droppedCount int
+	capacity     int
+}
+
+func newAttributesMap(capacity int) *attributesMap {
+	lm := &attributesMap{
+		attributes: make(map[core.Key]*list.Element),
+		evictList:  list.New(),
+		capacity:   capacity,
+	}
+	return lm
+}
+
+func (am *attributesMap) add(kv core.KeyValue) {
+	// Check for existing item
+	if ent, ok := am.attributes[kv.Key]; ok {
+		am.evictList.MoveToFront(ent)
+		ent.Value = &kv
+		return
+	}
+
+	// Add new item
+	entry := am.evictList.PushFront(&kv)
+	am.attributes[kv.Key] = entry
+
+	// Verify size not exceeded
+	if am.evictList.Len() > am.capacity {
+		am.removeOldest()
+		am.droppedCount++
+	}
+}
+
+func (am *attributesMap) toSpanData(sd *trace.SpanData) {
+	len := am.evictList.Len()
+	if len == 0 {
+		return
+	}
+
+	attributes := make([]core.KeyValue, 0, len)
+	for ent := am.evictList.Back(); ent != nil; ent = ent.Prev() {
+		if value, ok := ent.Value.(*core.KeyValue); ok {
+			attributes = append(attributes, *value)
+		}
+	}
+
+	sd.Attributes = attributes
+	sd.DroppedAttributeCount = am.droppedCount
+}
+
+// removeOldest removes the oldest item from the cache.
+func (am *attributesMap) removeOldest() {
+	ent := am.evictList.Back()
+	if ent != nil {
+		am.evictList.Remove(ent)
+		kv := ent.Value.(*core.KeyValue)
+		delete(am.attributes, kv.Key)
+	}
+}

sdk/trace/span.go

@@ -38,9 +38,9 @@ type span struct {
 	mu          sync.Mutex // protects the contents of *data (but not the pointer value.)
 	spanContext core.SpanContext
 
-	// lruAttributes are capped at configured limit. When the capacity is reached an oldest entry
+	// attributes are capped at configured limit. When the capacity is reached an oldest entry
 	// is removed to create room for a new entry.
-	lruAttributes *lruMap
+	attributes *attributesMap
 
 	// messageEvents are stored in FIFO queue capped by configured limit.
 	messageEvents *evictedQueue
@@ -228,10 +228,9 @@ func (s *span) makeSpanData() *export.SpanData {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	sd = *s.data
-	if s.lruAttributes.simpleLruMap.Len() > 0 {
-		sd.Attributes = s.lruAttributesToAttributeMap()
-		sd.DroppedAttributeCount = s.lruAttributes.droppedCount
-	}
+
+	s.attributes.toSpanData(&sd)
+
 	if len(s.messageEvents.queue) > 0 {
 		sd.MessageEvents = s.interfaceArrayToMessageEventArray()
 		sd.DroppedMessageEventCount = s.messageEvents.droppedCount
@@ -259,24 +258,11 @@ func (s *span) interfaceArrayToMessageEventArray() []export.Event {
 	return messageEventArr
 }
 
-func (s *span) lruAttributesToAttributeMap() []core.KeyValue {
-	attributes := make([]core.KeyValue, 0, s.lruAttributes.simpleLruMap.Len())
-	for _, key := range s.lruAttributes.simpleLruMap.Keys() {
-		value, ok := s.lruAttributes.simpleLruMap.Get(key)
-		if ok {
-			key := key.(core.Key)
-			value := value.(core.Value)
-			attributes = append(attributes, core.KeyValue{Key: key, Value: value})
-		}
-	}
-	return attributes
-}
-
 func (s *span) copyToCappedAttributes(attributes ...core.KeyValue) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	for _, a := range attributes {
-		s.lruAttributes.add(a.Key, a.Value)
+		s.attributes.add(a)
 	}
 }
 
@@ -328,7 +314,7 @@ func startSpanInternal(tr *tracer, name string, parent core.SpanContext, remoteP
 		Name:            name,
 		HasRemoteParent: remoteParent,
 	}
-	span.lruAttributes = newLruMap(cfg.MaxAttributesPerSpan)
+	span.attributes = newAttributesMap(cfg.MaxAttributesPerSpan)
 	span.messageEvents = newEvictedQueue(cfg.MaxEventsPerSpan)
 	span.links = newEvictedQueue(cfg.MaxLinksPerSpan)