opentracing -> opencensus (#802)

* update vendor directory, add go.opencensus.io

* update imports

* oops

* s/opentracing/opencensus/ & remove prometheus / zipkin stuff & remove old stats

* the dep train rides again

* fix gin build

* deps from last guy

* start in on the agent metrics

* she builds

* remove tags for now, cardinality error is fussing. subscribe instead of register

* update to patched version of opencensus to proceed for now TODO switch to a release

* meh

fix imports

* println debug the bad boys

* lace it with the tags

* update deps again

* fix all inconsistent cardinality errors

* add our own logger

* fix init

* fix oom measure

* remove bugged removal code

* fix s3 measures

* fix prom handler nil

vendor/github.com/google/btree/btree_test.go

@@ -687,3 +687,84 @@ func TestCloneConcurrentOperations(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkDeleteAndRestore(b *testing.B) {
+	items := perm(16392)
+	b.ResetTimer()
+	b.Run(`CopyBigFreeList`, func(b *testing.B) {
+		fl := NewFreeList(16392)
+		tr := NewWithFreeList(*btreeDegree, fl)
+		for _, v := range items {
+			tr.ReplaceOrInsert(v)
+		}
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			dels := make([]Item, 0, tr.Len())
+			tr.Ascend(ItemIterator(func(b Item) bool {
+				dels = append(dels, b)
+				return true
+			}))
+			for _, del := range dels {
+				tr.Delete(del)
+			}
+			// tr is now empty, we make a new empty copy of it.
+			tr = NewWithFreeList(*btreeDegree, fl)
+			for _, v := range items {
+				tr.ReplaceOrInsert(v)
+			}
+		}
+	})
+	b.Run(`Copy`, func(b *testing.B) {
+		tr := New(*btreeDegree)
+		for _, v := range items {
+			tr.ReplaceOrInsert(v)
+		}
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			dels := make([]Item, 0, tr.Len())
+			tr.Ascend(ItemIterator(func(b Item) bool {
+				dels = append(dels, b)
+				return true
+			}))
+			for _, del := range dels {
+				tr.Delete(del)
+			}
+			// tr is now empty, we make a new empty copy of it.
+			tr = New(*btreeDegree)
+			for _, v := range items {
+				tr.ReplaceOrInsert(v)
+			}
+		}
+	})
+	b.Run(`ClearBigFreelist`, func(b *testing.B) {
+		fl := NewFreeList(16392)
+		tr := NewWithFreeList(*btreeDegree, fl)
+		for _, v := range items {
+			tr.ReplaceOrInsert(v)
+		}
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			tr.Clear(true)
+			for _, v := range items {
+				tr.ReplaceOrInsert(v)
+			}
+		}
+	})
+	b.Run(`Clear`, func(b *testing.B) {
+		tr := New(*btreeDegree)
+		for _, v := range items {
+			tr.ReplaceOrInsert(v)
+		}
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			tr.Clear(true)
+			for _, v := range items {
+				tr.ReplaceOrInsert(v)
+			}
+		}
+	})
+}