services/keepstore/bufferpool_test.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package keepstore
   6
   7 import (
   8         "time"
   9
  10         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  11         "github.com/prometheus/client_golang/prometheus"
  12         . "gopkg.in/check.v1"
  13 )
  14
  15 var _ = Suite(&BufferPoolSuite{})
  16
  17 var bufferPoolTestSize = 10
  18
  19 type BufferPoolSuite struct{}
  20
  21 func (s *BufferPoolSuite) SetUpTest(c *C) {
  22         bufferPoolBlockSize = bufferPoolTestSize
  23 }
  24
  25 func (s *BufferPoolSuite) TearDownTest(c *C) {
  26         bufferPoolBlockSize = BlockSize
  27 }
  28
  29 func (s *BufferPoolSuite) TestBufferPoolBufSize(c *C) {
  30         bufs := newBufferPool(ctxlog.TestLogger(c), 2, prometheus.NewRegistry())
  31         b1 := bufs.Get()
  32         bufs.Get()
  33         bufs.Put(b1)
  34         b3 := bufs.Get()
  35         c.Check(len(b3), Equals, bufferPoolTestSize)
  36 }
  37
  38 func (s *BufferPoolSuite) TestBufferPoolUnderLimit(c *C) {
  39         bufs := newBufferPool(ctxlog.TestLogger(c), 3, prometheus.NewRegistry())
  40         b1 := bufs.Get()
  41         bufs.Get()
  42         testBufferPoolRace(c, bufs, b1, "Get")
  43 }
  44
  45 func (s *BufferPoolSuite) TestBufferPoolAtLimit(c *C) {
  46         bufs := newBufferPool(ctxlog.TestLogger(c), 2, prometheus.NewRegistry())
  47         b1 := bufs.Get()
  48         bufs.Get()
  49         testBufferPoolRace(c, bufs, b1, "Put")
  50 }
  51
  52 func testBufferPoolRace(c *C, bufs *bufferPool, unused []byte, expectWin string) {
  53         race := make(chan string)
  54         go func() {
  55                 bufs.Get()
  56                 time.Sleep(time.Millisecond)
  57                 race <- "Get"
  58         }()
  59         go func() {
  60                 time.Sleep(10 * time.Millisecond)
  61                 bufs.Put(unused)
  62                 race <- "Put"
  63         }()
  64         c.Check(<-race, Equals, expectWin)
  65         c.Check(<-race, Not(Equals), expectWin)
  66         close(race)
  67 }
  68
  69 func (s *BufferPoolSuite) TestBufferPoolReuse(c *C) {
  70         bufs := newBufferPool(ctxlog.TestLogger(c), 2, prometheus.NewRegistry())
  71         bufs.Get()
  72         last := bufs.Get()
  73         // The buffer pool is allowed to throw away unused buffers
  74         // (e.g., during sync.Pool's garbage collection hook, in the
  75         // the current implementation). However, if unused buffers are
  76         // getting thrown away and reallocated more than {arbitrary
  77         // frequency threshold} during a busy loop, it's not acting
  78         // much like a buffer pool.
  79         allocs := 1000
  80         reuses := 0
  81         for i := 0; i < allocs; i++ {
  82                 bufs.Put(last)
  83                 next := bufs.Get()
  84                 copy(last, []byte("last"))
  85                 copy(next, []byte("next"))
  86                 if last[0] == 'n' {
  87                         reuses++
  88                 }
  89                 last = next
  90         }
  91         c.Check(reuses > allocs*95/100, Equals, true)
  92 }