bbp

README

Package bbp provides efficient byte buffer pools with anti-memory-waste protection.

Byte buffers acquired from this package may be put back to the pool, but they do not need to; if they are returned, they will be recycled and reused, otherwise they will be garbage collected as usual.

The methods within this package and all Pool instances share the same underlying sized byte slice pools. The byte buffers provided by this package has a minimum limit of 64B and a maximum limit of 4MB, byte slice with size not in the range will be allocated directly from Go runtime, and won't be recycled for reuse.

Documentation

Overview

Package bbp provides efficient byte buffer pools with anti-memory-waste protection.

Byte buffers acquired from this package may be put back to the pool, but they do not need to; if they are returned, they will be recycled and reused, otherwise they will be garbage collected as usual.

The methods within this package and all `Pool` instances share the same underlying sized byte slice pools. The byte buffers provided by this package has a minimum limit of 64B and a maximum limit of 4MB, byte slice with size not in the range will be allocated directly from Go runtime, and won't be recycled for reuse.

Index

• Constants
• func Get(length, capacity int) []byte
• func Grow(buf []byte, n int, reuseBuf bool) []byte
• func Put(buf []byte)
• func PutBuffer(buf *Buffer)
• type Buffer
  • func NewBuffer(capacity int) *Buffer
  • func (b *Buffer) Append(f func([]byte) []byte)
  • func (b *Buffer) Bytes() []byte
  • func (b *Buffer) Clone() *Buffer
  • func (b *Buffer) Copy() []byte
  • func (b *Buffer) Grow(n int)
  • func (b *Buffer) Len() int
  • func (b *Buffer) ReadFrom(r io.Reader) (int64, error)
  • func (b *Buffer) Reset()
  • func (b *Buffer) Set(p []byte)
  • func (b *Buffer) SetString(s string)
  • func (b *Buffer) String() string
  • func (b *Buffer) StringUnsafe() string
  • func (b *Buffer) Write(p []byte) (int, error)
  • func (b *Buffer) WriteByte(c byte) error
  • func (b *Buffer) WriteRune(r rune) (n int, err error)
  • func (b *Buffer) WriteString(s string) (int, error)
  • func (b *Buffer) WriteStrings(s []string) (int, error)
  • func (b *Buffer) WriteTo(w io.Writer) (int64, error)
• type Pool
  • func NewPool(r Recorder) *Pool
  • func (p *Pool) Get() []byte
  • func (p *Pool) GetBuffer() *Buffer
  • func (p *Pool) Put(buf []byte)
  • func (p *Pool) PutBuffer(buf *Buffer)
• type Recorder
  • func (p *Recorder) Record(n int)
  • func (p *Recorder) Size() int

Examples

• Buffer
• Get
• Grow
• Pool

Constants

const MinRead = 512

MinRead is the minimum slice size passed to a Read call by Buffer.ReadFrom.

Functions

func Get

func Get(length, capacity int) []byte

Get returns a byte slice from the pool with specified length and capacity. When you finish the work with the buffer, you may call Put to put it back to the pool for reusing.

Example

buf := Get(0, 50)
defer Put(buf)

buf = append(buf, "first line\n"...)
buf = append(buf, "second line\n"...)

fmt.Println(string(buf))

Output:

first line
second line

func Grow

func Grow(buf []byte, n int, reuseBuf bool) []byte

Grow checks capacity of buf, it returns a new byte buffer from the pool, if necessary, to guarantee space for another n bytes. After Grow(n), at least n bytes can be appended to the returned buffer without another allocation. If n is negative, Grow will panic.

Note that if reuseBuf is true and a new slice is returned, the old buf will be put back to the pool, the caller must not retain reference to the old buf and must not access it again, else data race happens.

Example

buf := []byte("first line\n")
buf = Grow(buf, 50, true)
buf = append(buf, "second line\n"...)

fmt.Println(string(buf))
Put(buf)

Output:

first line
second line

func Put

func Put(buf []byte)

Put puts back a byte slice to the pool for reusing.

The byte slice mustn't be touched after returning it to the pool, otherwise data races will occur.

func PutBuffer

func PutBuffer(buf *Buffer)

PutBuffer puts back a Buffer to the pool for reusing.

The buffer mustn't be touched after returning it to the pool, otherwise data races will occur.

Types

type Buffer

type Buffer struct {
	// contains filtered or unexported fields
}

Buffer provides byte buffer, which can be used for minimizing memory allocations.

Buffer may be used with functions appending data to the underlying []byte slice. See example code for details.

Use NewBuffer for obtaining a buffer with specified capacity. The zero value for Buffer is an empty buffer ready to use.

Example

var buf Buffer
defer PutBuffer(&buf)

buf.WriteString("first line\n")
buf.Write([]byte("second line\n"))
buf.buf = append(buf.buf, "third line\n"...)

fmt.Println(buf.String())

Output:

first line
second line
third line

func NewBuffer

func NewBuffer(capacity int) *Buffer

NewBuffer creates a new Buffer with specified capacity. When you finish the work with the buffer, you may call PutBuffer to put it back to the pool for reusing.

func (*Buffer) Append

func (b *Buffer) Append(f func([]byte) []byte)

Append accepts a function which append data to the underlying byte slice.

func (*Buffer) Bytes

func (b *Buffer) Bytes() []byte

Bytes returns the underlying byte slice, i.e. all the bytes accumulated in the buffer.

Note that this method doesn't copy the underlying byte slice, the caller should either copy the byte slice explicitly or don't return the Buffer back to the pool, otherwise data race will occur. You may use Buffer.Copy to get a copy of the underlying byte slice.

func (*Buffer) Clone

func (b *Buffer) Clone() *Buffer

Clone returns a new copy of the buffer, including the underlying byte slice.

func (*Buffer) Copy

func (b *Buffer) Copy() []byte

Copy returns a copy of the underlying byte slice.

func (*Buffer) Grow

func (b *Buffer) Grow(n int)

Grow grows the buffer's capacity, if necessary, to guarantee space for another n bytes. After Grow(n), at least n bytes can be written to the buffer without another allocation. If n is negative, Grow will panic.

func (*Buffer) Len

func (b *Buffer) Len() int

Len returns the size of the byte buffer.

func (*Buffer) ReadFrom

func (b *Buffer) ReadFrom(r io.Reader) (int64, error)

ReadFrom implements io.ReaderFrom.

The function appends all the data read from r to b.

func (*Buffer) Reset

func (b *Buffer) Reset()

Reset re-slice the underlying byte slice to empty.

func (*Buffer) Set

func (b *Buffer) Set(p []byte)

Set first re-slice the underlying byte slice to empty, then write p to the buffer.

func (*Buffer) SetString

func (b *Buffer) SetString(s string)

SetString first re-slice the underlying byte slice to empty, then write s to the buffer.

func (*Buffer) String

func (b *Buffer) String() string

String returns a string copy of the underlying byte slice.

func (*Buffer) StringUnsafe

func (b *Buffer) StringUnsafe() string

StringUnsafe is equivalent to String, but the string that it returns is _NOT_ copied, so modifying this buffer after calling StringUnsafe will lead to undefined behavior.

func (*Buffer) Write

func (b *Buffer) Write(p []byte) (int, error)

Write implements io.Writer - it appends p to the underlying byte buffer.

func (*Buffer) WriteByte

func (b *Buffer) WriteByte(c byte) error

WriteByte appends the byte c to the buffer. The purpose of this function is bytes.Buffer compatibility.

func (*Buffer) WriteRune

func (b *Buffer) WriteRune(r rune) (n int, err error)

WriteRune appends the UTF-8 encoding of Unicode code point r to the buffer. The purpose of this function is bytes.Buffer compatibility.

func (*Buffer) WriteString

func (b *Buffer) WriteString(s string) (int, error)

WriteString appends s to the underlying byte slice.

func (*Buffer) WriteStrings

func (b *Buffer) WriteStrings(s []string) (int, error)

WriteStrings appends a slice of strings to the underlying byte slice.

func (*Buffer) WriteTo

func (b *Buffer) WriteTo(w io.Writer) (int64, error)

WriteTo implements io.WriterTo.

type Pool

type Pool struct {
	// contains filtered or unexported fields
}

Pool is a byte buffer pool which reuses byte slice. It uses dynamic calibrating (which is a little atomic operations) to try best to match the workload.

Generally, if the size and capacity is known in advance, you may use the exported function Get(length, capacity) to get a properly sized byte buffer. However, if the buffer size is uncertain in advance, you may want to use this Pool. For different workloads, dedicated Pool instances are recommended, the dynamic calibrating will help to reduce memory waste.

All Pool instances share the same underlying sized byte slice pools. The byte buffers provided by Pool has a minimum limit of 64B and a maximum limit of 4MB, byte slice with size not in the range will be allocated directly from the operating system, and won't be recycled for reuse.

The zero value for Pool is ready to use. A Pool value shall not be copied after initialized.

Example

var pool Pool
buf := pool.GetBuffer()
defer PutBuffer(buf)

buf.WriteString("first line\n")
buf.Write([]byte("second line\n"))

fmt.Println(buf.String())

Output:

first line
second line

func NewPool

func NewPool(r Recorder) *Pool

NewPool creates a new Pool instance using given Recorder.

In most cases, declaring a Pool variable is sufficient to initialize a Pool.

func (*Pool) Get

func (p *Pool) Get() []byte

Get returns a byte slice buffer from the pool. The returned buffer may be put back to the pool for reusing.

func (*Pool) GetBuffer

func (p *Pool) GetBuffer() *Buffer

GetBuffer returns a Buffer from the pool with dynamic calibrated default capacity. The returned Buffer may be put back to the pool for reusing.

func (*Pool) Put

func (p *Pool) Put(buf []byte)

Put puts back a byte slice buffer to the pool for reusing.

The buf mustn't be touched after returning it to the pool, otherwise data races will occur.

func (*Pool) PutBuffer

func (p *Pool) PutBuffer(buf *Buffer)

PutBuffer puts back a Buffer to the pool for reusing.

The buf mustn't be touched after returning it to the pool, otherwise, data races will occur.

type Recorder

type Recorder struct {

	// DefaultSize optionally configs the initial default size to be used.
	// Default is 1024 bytes.
	DefaultSize int

	// CalibrateInterval optionally configs the interval to do calibrating.
	// Default is 3 minutes.
	CalibrateInterval time.Duration

	// ResizePercentile optionally configs the percentile to reset the
	// default size when doing calibrating, the value should be in range
	// [50, 100). Default is 95.
	ResizePercentile int
	// contains filtered or unexported fields
}

Recorder helps to record most frequently used buffer size. It calibrates the recorded size data in running, thus it can dynamically adjust according to recent workload.

func (*Recorder) Record

func (p *Recorder) Record(n int)

Record records a used buffer size n. The max recordable size is 4MB, if n is larger than 4MB, it records 4MB.

func (*Recorder) Size

func (p *Recorder) Size() int

Size returns the current most frequently used buffer size.