github.com/cockroachdb/pebble@v0.0.0-20231214172447-ab4952c5f87b/sstable/unsafe_test.go (about)

     1  // Copyright 2018 The LevelDB-Go and Pebble Authors. All rights reserved. Use
     2  // of this source code is governed by a BSD-style license that can be found in
     3  // the LICENSE file.
     4  
     5  package sstable
     6  
     7  import (
     8  	"encoding/binary"
     9  	"fmt"
    10  	"io"
    11  	"testing"
    12  	"time"
    13  	"unsafe"
    14  
    15  	"github.com/stretchr/testify/require"
    16  	"golang.org/x/exp/rand"
    17  )
    18  
    19  func TestGetBytes(t *testing.T) {
    20  	const size = (1 << 31) - 1
    21  	// No need to actually allocate a huge slice, which can cause OOM on small
    22  	// machines (like the GitHub CI runners).
    23  	block := make([]byte, 100)
    24  	data := getBytes(unsafe.Pointer(&block[0]), size)
    25  	require.EqualValues(t, size, len(data))
    26  }
    27  
    28  func TestDecodeVarint(t *testing.T) {
    29  	vals := []uint32{
    30  		0,
    31  		1,
    32  		1 << 7,
    33  		1 << 8,
    34  		1 << 14,
    35  		1 << 15,
    36  		1 << 20,
    37  		1 << 21,
    38  		1 << 28,
    39  		1 << 29,
    40  		1 << 31,
    41  	}
    42  	buf := make([]byte, 5)
    43  	for _, v := range vals {
    44  		binary.PutUvarint(buf, uint64(v))
    45  		u, _ := decodeVarint(unsafe.Pointer(&buf[0]))
    46  		if v != u {
    47  			fmt.Printf("%d %d\n", v, u)
    48  		}
    49  	}
    50  }
    51  
    52  func BenchmarkDecodeVarint(b *testing.B) {
    53  	rng := rand.New(rand.NewSource(uint64(time.Now().UnixNano())))
    54  	vals := make([]unsafe.Pointer, 10000)
    55  	for i := range vals {
    56  		buf := make([]byte, 5)
    57  		binary.PutUvarint(buf, uint64(rng.Uint32()))
    58  		vals[i] = unsafe.Pointer(&buf[0])
    59  	}
    60  
    61  	b.ResetTimer()
    62  	var ptr unsafe.Pointer
    63  	for i, n := 0, 0; i < b.N; i += n {
    64  		n = len(vals)
    65  		if n > b.N-i {
    66  			n = b.N - i
    67  		}
    68  		for j := 0; j < n; j++ {
    69  			_, ptr = decodeVarint(vals[j])
    70  		}
    71  	}
    72  	if testing.Verbose() {
    73  		fmt.Fprint(io.Discard, ptr)
    74  	}
    75  }