1 files changed, 130 insertions, 0 deletions

diff --git a/vendor/go.opencensus.io/trace/spanbucket.go b/vendor/go.opencensus.io/trace/spanbucket.go
new file mode 100644
index 0000000..fbabad3
--- /dev/null
+++ b/vendor/go.opencensus.io/trace/spanbucket.go
@@ -0,0 +1,130 @@
+// Copyright 2017, OpenCensus 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 (
+        "time"
+)
+
+// samplePeriod is the minimum time between accepting spans in a single bucket.
+const samplePeriod = time.Second
+
+// defaultLatencies contains the default latency bucket bounds.
+// TODO: consider defaults, make configurable
+var defaultLatencies = [...]time.Duration{
+        10 * time.Microsecond,
+        100 * time.Microsecond,
+        time.Millisecond,
+        10 * time.Millisecond,
+        100 * time.Millisecond,
+        time.Second,
+        10 * time.Second,
+        time.Minute,
+}
+
+// bucket is a container for a set of spans for a particular error code or latency range.
+type bucket struct {
+        nextTime  time.Time   // next time we can accept a span
+        buffer    []*SpanData // circular buffer of spans
+        nextIndex int         // location next SpanData should be placed in buffer
+        overflow  bool        // whether the circular buffer has wrapped around
+}
+
+func makeBucket(bufferSize int) bucket {
+        return bucket{
+                buffer: make([]*SpanData, bufferSize),
+        }
+}
+
+// add adds a span to the bucket, if nextTime has been reached.
+func (b *bucket) add(s *SpanData) {
+        if s.EndTime.Before(b.nextTime) {
+                return
+        }
+        if len(b.buffer) == 0 {
+                return
+        }
+        b.nextTime = s.EndTime.Add(samplePeriod)
+        b.buffer[b.nextIndex] = s
+        b.nextIndex++
+        if b.nextIndex == len(b.buffer) {
+                b.nextIndex = 0
+                b.overflow = true
+        }
+}
+
+// size returns the number of spans in the bucket.
+func (b *bucket) size() int {
+        if b.overflow {
+                return len(b.buffer)
+        }
+        return b.nextIndex
+}
+
+// span returns the ith span in the bucket.
+func (b *bucket) span(i int) *SpanData {
+        if !b.overflow {
+                return b.buffer[i]
+        }
+        if i < len(b.buffer)-b.nextIndex {
+                return b.buffer[b.nextIndex+i]
+        }
+        return b.buffer[b.nextIndex+i-len(b.buffer)]
+}
+
+// resize changes the size of the bucket to n, keeping up to n existing spans.
+func (b *bucket) resize(n int) {
+        cur := b.size()
+        newBuffer := make([]*SpanData, n)
+        if cur < n {
+                for i := 0; i < cur; i++ {
+                        newBuffer[i] = b.span(i)
+                }
+                b.buffer = newBuffer
+                b.nextIndex = cur
+                b.overflow = false
+                return
+        }
+        for i := 0; i < n; i++ {
+                newBuffer[i] = b.span(i + cur - n)
+        }
+        b.buffer = newBuffer
+        b.nextIndex = 0
+        b.overflow = true
+}
+
+// latencyBucket returns the appropriate bucket number for a given latency.
+func latencyBucket(latency time.Duration) int {
+        i := 0
+        for i < len(defaultLatencies) && latency >= defaultLatencies[i] {
+                i++
+        }
+        return i
+}
+
+// latencyBucketBounds returns the lower and upper bounds for a latency bucket
+// number.
+//
+// The lower bound is inclusive, the upper bound is exclusive (except for the
+// last bucket.)
+func latencyBucketBounds(index int) (lower time.Duration, upper time.Duration) {
+        if index == 0 {
+                return 0, defaultLatencies[index]
+        }
+        if index == len(defaultLatencies) {
+                return defaultLatencies[index-1], 1<<63 - 1
+        }
+        return defaultLatencies[index-1], defaultLatencies[index]
+}