Package expvar

import "expvar"
Overview
Index
Documentation

Overview

Package expvar provides a standardized interface to public variables, such as operation counters in servers. It exposes these variables via HTTP at /debug/vars in JSON format.

Operations to set or modify these public variables are atomic.

In addition to adding the HTTP handler, this package registers the following variables:

cmdline   os.Args
memstats  runtime.Memstats

The package is sometimes only imported for the side effect of registering its HTTP handler and the above variables. To use it this way, link this package into your program:

import _ "expvar"

Index

func Do(f func(KeyValue))
func Handler() http.Handler
func Publish(name string, v Var)
type Float
func NewFloat(name string) *Float
func (v *Float) Add(delta float64)
func (v *Float) Set(value float64)
func (v *Float) String() string
func (v *Float) Value() float64
type Func
func (f Func) String() string
func (f Func) Value() interface{}
type Int
func NewInt(name string) *Int
func (v *Int) Add(delta int64)
func (v *Int) Set(value int64)
func (v *Int) String() string
func (v *Int) Value() int64
type KeyValue
type Map
func NewMap(name string) *Map
func (v *Map) Add(key string, delta int64)
func (v *Map) AddFloat(key string, delta float64)
func (v *Map) Do(f func(KeyValue))
func (v *Map) Get(key string) Var
func (v *Map) Init() *Map
func (v *Map) Set(key string, av Var)
func (v *Map) String() string
type String
func NewString(name string) *String
func (v *String) Set(value string)
func (v *String) String() string
func (v *String) Value() string
type Var
func Get(name string) Var

Documentation

func Do

func Do(f func(KeyValue))

Do calls f for each exported variable. The global variable map is locked during the iteration, but existing entries may be concurrently updated.

func Handler

func Handler() http.Handler

Handler returns the expvar HTTP Handler.

This is only needed to install the handler in a non-standard location.

func Publish

func Publish(name string, v Var)

Publish declares a named exported variable. This should be called from a package's init function when it creates its Vars. If the name is already registered then this will log.Panic.

type Float

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

Float is a 64-bit float variable that satisfies the Var interface.

func NewFloat

func NewFloat(name string) *Float

func Float.Add

func (v *Float) Add(delta float64)

Add adds delta to v.

func Float.Set

func (v *Float) Set(value float64)

Set sets v to value.

func Float.String

func (v *Float) String() string

func Float.Value

func (v *Float) Value() float64

type Func

type Func func() interface{}

Func implements Var by calling the function and formatting the returned value using JSON.

func Func.String

func (f Func) String() string

func Func.Value

func (f Func) Value() interface{}

type Int

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

Int is a 64-bit integer variable that satisfies the Var interface.

func NewInt

func NewInt(name string) *Int

func Int.Add

func (v *Int) Add(delta int64)

func Int.Set

func (v *Int) Set(value int64)

func Int.String

func (v *Int) String() string

func Int.Value

func (v *Int) Value() int64

type KeyValue

type KeyValue struct {
    Key   string
    Value Var
}

KeyValue represents a single entry in a Map.

type Map

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

Map is a string-to-Var map variable that satisfies the Var interface.

func NewMap

func NewMap(name string) *Map

func Map.Add

func (v *Map) Add(key string, delta int64)

Add adds delta to the *Int value stored under the given map key.

func Map.AddFloat

func (v *Map) AddFloat(key string, delta float64)

AddFloat adds delta to the *Float value stored under the given map key.

func Map.Do

func (v *Map) Do(f func(KeyValue))

Do calls f for each entry in the map. The map is locked during the iteration, but existing entries may be concurrently updated.

func Map.Get

func (v *Map) Get(key string) Var

func Map.Init

func (v *Map) Init() *Map

Init removes all keys from the map.

func Map.Set

func (v *Map) Set(key string, av Var)

func Map.String

func (v *Map) String() string

type String

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

String is a string variable, and satisfies the Var interface.

func NewString

func NewString(name string) *String

func String.Set

func (v *String) Set(value string)

func String.String

func (v *String) String() string

String implements the Val interface. To get the unquoted string use Value.

func String.Value

func (v *String) Value() string

type Var

type Var interface {
    // String returns a valid JSON value for the variable.
    // Types with String methods that do not return valid JSON
    // (such as time.Time) must not be used as a Var.
    String() string
}

Var is an abstract type for all exported variables.

func Get

func Get(name string) Var

Get retrieves a named exported variable. It returns nil if the name has not been registered.