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Package expvar

import "expvar"
Overview
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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"

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

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

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

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

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

type Func func() interface{}

func (Func) String

func (f Func) String() string

func (Func) Value

func (f Func) Value() interface{}

type Int

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

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

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

KeyValue represents a single entry in a Map.

type KeyValue struct {
    Key   string
    Value Var
}

type Map

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

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

func NewMap

func NewMap(name string) *Map

func (*Map) Add

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

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

func (*Map) Set

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

func (*Map) String

func (v *Map) String() string

type String

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

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

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

Var is an abstract type for all exported variables.

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
}

func Get

func Get(name string) Var

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