vendor: update all dependencies to latest versions

vendor/cloud.google.com/go/pubsub/internal/distribution/distribution.go

@@ -0,0 +1,70 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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 distribution
+
+import (
+	"log"
+	"math"
+	"sort"
+	"sync/atomic"
+)
+
+// D is a distribution. Methods of D can be called concurrently by multiple
+// goroutines.
+type D struct {
+	buckets []uint64
+}
+
+// New creates a new distribution capable of holding values from 0 to n-1.
+func New(n int) *D {
+	return &D{
+		buckets: make([]uint64, n),
+	}
+}
+
+// Record records value v to the distribution.
+// To help with distributions with long tails, if v is larger than the maximum value,
+// Record records the maximum value instead.
+// If v is negative, Record panics.
+func (d *D) Record(v int) {
+	if v < 0 {
+		log.Panicf("Record: value out of range: %d", v)
+	} else if v >= len(d.buckets) {
+		v = len(d.buckets) - 1
+	}
+	atomic.AddUint64(&d.buckets[v], 1)
+}
+
+// Percentile computes the p-th percentile of the distribution where
+// p is between 0 and 1.
+func (d *D) Percentile(p float64) int {
+	// NOTE: This implementation uses the nearest-rank method.
+	// https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method
+
+	if p < 0 || p > 1 {
+		log.Panicf("Percentile: percentile out of range: %f", p)
+	}
+
+	bucketSums := make([]uint64, len(d.buckets))
+	var sum uint64
+	for i := range bucketSums {
+		sum += atomic.LoadUint64(&d.buckets[i])
+		bucketSums[i] = sum
+	}
+
+	total := bucketSums[len(bucketSums)-1]
+	target := uint64(math.Ceil(float64(total) * p))
+	return sort.Search(len(bucketSums), func(i int) bool { return bucketSums[i] >= target })
+}

vendor/cloud.google.com/go/pubsub/internal/distribution/distribution_test.go

@@ -0,0 +1,94 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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 distribution
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestDistribution(t *testing.T) {
+	// These tests come from examples in https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method
+	tests := []struct {
+		// values in distribution
+		vals []int
+
+		// percentiles and expected percentile values
+		pp []float64
+		vv []int
+	}{
+		{
+			vals: []int{15, 20, 35, 40, 50},
+			pp:   []float64{0.05, 0.3, 0.4, 0.5, 1},
+			vv:   []int{15, 20, 20, 35, 50},
+		},
+		{
+			vals: []int{3, 6, 7, 8, 8, 10, 13, 15, 16, 20},
+			pp:   []float64{0.25, 0.5, 0.75, 1},
+			vv:   []int{7, 8, 15, 20},
+		},
+		{
+			vals: []int{3, 6, 7, 8, 8, 9, 10, 13, 15, 16, 20},
+			pp:   []float64{0.25, 0.5, 0.75, 1},
+			vv:   []int{7, 9, 15, 20},
+		},
+	}
+
+	maxVal := 0
+	for _, tst := range tests {
+		for _, v := range tst.vals {
+			if maxVal < v {
+				maxVal = v
+			}
+		}
+	}
+
+	for _, tst := range tests {
+		d := New(maxVal + 1)
+		for _, v := range tst.vals {
+			d.Record(v)
+		}
+		for i, p := range tst.pp {
+			got, want := d.Percentile(p), tst.vv[i]
+			if got != want {
+				t.Errorf("d=%v, d.Percentile(%f)=%d, want %d", d, p, got, want)
+			}
+		}
+	}
+}
+
+func TestRace(t *testing.T) {
+	const N int = 1e3
+	const parallel = 2
+
+	d := New(N)
+
+	var wg sync.WaitGroup
+	wg.Add(parallel)
+	for i := 0; i < parallel; i++ {
+		go func() {
+			for i := 0; i < N; i++ {
+				d.Record(i)
+			}
+			wg.Done()
+		}()
+	}
+
+	for i := 0; i < N; i++ {
+		if p := d.Percentile(0.5); p > N {
+			t.Fatalf("d.Percentile(0.5)=%d, expected to be at most %d", p, N)
+		}
+	}
+}