From 36c5edd8d9e6c13af26733e5c820eae0598203fe Mon Sep 17 00:00:00 2001 From: Michael Anthony Knyszek Date: Thu, 6 Aug 2020 20:36:49 +0000 Subject: runtime: add timeHistogram type This change adds a concurrent HDR time histogram to the runtime with tests. It also adds a function to generate boundaries for use by the metrics package. For #37112. Change-Id: Ifbef8ddce8e3a965a0dcd58ccd4915c282ae2098 Reviewed-on: https://go-review.googlesource.com/c/go/+/247046 Run-TryBot: Michael Knyszek TryBot-Result: Go Bot Trust: Michael Knyszek Reviewed-by: Michael Pratt --- src/runtime/histogram_test.go | 58 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 src/runtime/histogram_test.go (limited to 'src/runtime/histogram_test.go') diff --git a/src/runtime/histogram_test.go b/src/runtime/histogram_test.go new file mode 100644 index 0000000000..5f5b28f784 --- /dev/null +++ b/src/runtime/histogram_test.go @@ -0,0 +1,58 @@ +// Copyright 2020 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime_test + +import ( + . "runtime" + "testing" +) + +var dummyTimeHistogram TimeHistogram + +func TestTimeHistogram(t *testing.T) { + // We need to use a global dummy because this + // could get stack-allocated with a non-8-byte alignment. + // The result of this bad alignment is a segfault on + // 32-bit platforms when calling Record. + h := &dummyTimeHistogram + + // Record exactly one sample in each bucket. + for i := 0; i < TimeHistNumSuperBuckets; i++ { + var base int64 + if i > 0 { + base = int64(1) << (i + TimeHistSubBucketBits - 1) + } + for j := 0; j < TimeHistNumSubBuckets; j++ { + v := int64(j) + if i > 0 { + v <<= i - 1 + } + h.Record(base + v) + } + } + // Hit the overflow bucket. + h.Record(int64(^uint64(0) >> 1)) + + // Check to make sure there's exactly one count in each + // bucket. + for i := uint(0); i < TimeHistNumSuperBuckets; i++ { + for j := uint(0); j < TimeHistNumSubBuckets; j++ { + c, ok := h.Count(i, j) + if !ok { + t.Errorf("hit overflow bucket unexpectedly: (%d, %d)", i, j) + } else if c != 1 { + t.Errorf("bucket (%d, %d) has count that is not 1: %d", i, j, c) + } + } + } + c, ok := h.Count(TimeHistNumSuperBuckets, 0) + if ok { + t.Errorf("expected to hit overflow bucket: (%d, %d)", TimeHistNumSuperBuckets, 0) + } + if c != 1 { + t.Errorf("overflow bucket has count that is not 1: %d", c) + } + dummyTimeHistogram = TimeHistogram{} +} -- cgit v1.2.1