iobp

Documentation

Overview

Package iobp provides useful implementations of interfaces defined in stdlib io package.

Index

• type CountingSink
  • func (cs CountingSink) Size() int64
  • func (cs *CountingSink) Write(buf []byte) (int, error)

Examples

• CountingSink

Types

type CountingSink

type CountingSink int64

CountingSink is an io.Writer implementation that discards all incoming data but tracks how many bytes were "written".

This can be used as a sink for encoders or as an additional output via a MultiWriter to track data sizes without buffering all of the data in memory.

A Write to a CountingSink cannot fail. A CountingSink is not safe for concurrent use.

Example

This example demonstrates how to use CountingSink to count the size of a json-serialized object.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/reddit/baseplate.go/iobp"
)

func main() {
	// The json string would be "[0,1,2,3,4]\n", so the size should be 12.
	object := []int{0, 1, 2, 3, 4}

	var sink iobp.CountingSink
	if err := json.NewEncoder(&sink).Encode(object); err != nil {
		panic(err)
	}
	fmt.Printf("JSON size for %#v: %d\n", object, sink.Size())

}

Output:

JSON size for []int{0, 1, 2, 3, 4}: 12

func (CountingSink) Size

func (cs CountingSink) Size() int64

Size returns the current counted size.

func (*CountingSink) Write

func (cs *CountingSink) Write(buf []byte) (int, error)