Documentation

Overview

Package label provides key and value labels.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func NewSetWithFiltered

func NewSetWithFiltered(kvs []KeyValue, filter Filter) (Set, []KeyValue)

NewSetWithFiltered returns a new `Set`. See the documentation for `NewSetWithSortableFiltered` for more details.

This call includes a `Filter` to include/exclude label keys from the return value. Excluded keys are returned as a slice of label values.

func NewSetWithSortableFiltered

func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (Set, []KeyValue)

NewSetWithSortableFiltered returns a new `Set`.

Duplicate keys are eliminated by taking the last value. This re-orders the input slice so that unique last-values are contiguous at the end of the slice.

This ensures the following:

- Last-value-wins semantics - Caller sees the reordering, but doesn't lose values - Repeated call preserve last-value wins.

Note that methods are defined on `*Set`, although this returns `Set`. Callers can avoid memory allocations by:

- allocating a `Sortable` for use as a temporary in this method - allocating a `Set` for storing the return value of this

constructor.

The result maintains a cache of encoded labels, by label.EncoderID. This value should not be copied after its first use.

The second `[]KeyValue` return value is a list of labels that were excluded by the Filter (if non-nil).

Types

type Distinct

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

Distinct wraps a variable-size array of `KeyValue`, constructed with keys in sorted order. This can be used as a map key or for equality checking between Sets.

func (Distinct) Valid

func (d Distinct) Valid() bool

Valid returns true if this value refers to a valid `*Set`.

type Encoder

type Encoder interface {
	// Encode returns the serialized encoding of the label
	// set using its Iterator.  This result may be cached
	// by a label.Set.
	Encode(iterator Iterator) string

	// ID returns a value that is unique for each class of
	// label encoder.  Label encoders allocate these using
	// `NewEncoderID`.
	ID() EncoderID
}

Encoder is a mechanism for serializing a label set into a specific string representation that supports caching, to avoid repeated serialization. An example could be an exporter encoding the label set into a wire representation.

func DefaultEncoder

func DefaultEncoder() Encoder

DefaultEncoder returns a label encoder that encodes labels in such a way that each escaped label's key is followed by an equal sign and then by an escaped label's value. All key-value pairs are separated by a comma.

Escaping is done by prepending a backslash before either a backslash, equal sign or a comma.

type EncoderID

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

EncoderID is used to identify distinct Encoder implementations, for caching encoded results.

func NewEncoderID

func NewEncoderID() EncoderID

NewEncoderID returns a unique label encoder ID. It should be called once per each type of label encoder. Preferably in init() or in var definition.

func (EncoderID) Valid

func (id EncoderID) Valid() bool

Valid returns true if this encoder ID was allocated by `NewEncoderID`. Invalid encoder IDs will not be cached.

type Filter

type Filter func(KeyValue) bool

Filter supports removing certain labels from label sets. When the filter returns true, the label will be kept in the filtered label set. When the filter returns false, the label is excluded from the filtered label set, and the label instead appears in the `removed` list of excluded labels.

type Iterator

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

Iterator allows iterating over the set of labels in order, sorted by key.

func (*Iterator) Attribute

func (i *Iterator) Attribute() KeyValue

Attribute is a synonym for Label().

func (*Iterator) IndexedLabel

func (i *Iterator) IndexedLabel() (int, KeyValue)

IndexedLabel returns current index and label. Must be called only after Next returns true.

func (*Iterator) Label

func (i *Iterator) Label() KeyValue

Label returns current KeyValue. Must be called only after Next returns true.

func (*Iterator) Len

func (i *Iterator) Len() int

Len returns a number of labels in the iterator's `*Set`.

func (*Iterator) Next

func (i *Iterator) Next() bool

Next moves the iterator to the next position. Returns false if there are no more labels.

func (*Iterator) ToSlice

func (i *Iterator) ToSlice() []KeyValue

ToSlice is a convenience function that creates a slice of labels from the passed iterator. The iterator is set up to start from the beginning before creating the slice.

type Key

type Key string

Key represents the key part in key-value pairs. It's a string. The allowed character set in the key depends on the use of the key.

func (Key) Array

func (k Key) Array(v interface{}) KeyValue

Array creates a KeyValue instance with a ARRAY Value.

If creating both key and a array value at the same time, then instead of calling Key(name).String(value) consider using a convenience function provided by the api/key package - key.Array(name, value).

func (Key) Bool

func (k Key) Bool(v bool) KeyValue

Bool creates a KeyValue instance with a BOOL Value.

If creating both key and a bool value at the same time, then instead of calling Key(name).Bool(value) consider using a convenience function provided by the api/key package - key.Bool(name, value).

func (Key) Defined

func (k Key) Defined() bool

Defined returns true for non-empty keys.

func (Key) Float32

func (k Key) Float32(v float32) KeyValue

Float32 creates a KeyValue instance with a FLOAT32 Value.

If creating both key and a float32 value at the same time, then instead of calling Key(name).Float32(value) consider using a convenience function provided by the api/key package - key.Float32(name, value).

func (Key) Float64

func (k Key) Float64(v float64) KeyValue

Float64 creates a KeyValue instance with a FLOAT64 Value.

If creating both key and a float64 value at the same time, then instead of calling Key(name).Float64(value) consider using a convenience function provided by the api/key package - key.Float64(name, value).

func (Key) Int

func (k Key) Int(v int) KeyValue

Int creates a KeyValue instance with either an INT32 or an INT64 Value, depending on whether the int type is 32 or 64 bits wide.

If creating both key and an int value at the same time, then instead of calling Key(name).Int(value) consider using a convenience function provided by the api/key package - key.Int(name, value).

func (Key) Int32

func (k Key) Int32(v int32) KeyValue

Int32 creates a KeyValue instance with an INT32 Value.

If creating both key and an int32 value at the same time, then instead of calling Key(name).Int32(value) consider using a convenience function provided by the api/key package - key.Int32(name, value).

func (Key) Int64

func (k Key) Int64(v int64) KeyValue

Int64 creates a KeyValue instance with an INT64 Value.

If creating both key and an int64 value at the same time, then instead of calling Key(name).Int64(value) consider using a convenience function provided by the api/key package - key.Int64(name, value).

func (Key) String

func (k Key) String(v string) KeyValue

String creates a KeyValue instance with a STRING Value.

If creating both key and a string value at the same time, then instead of calling Key(name).String(value) consider using a convenience function provided by the api/key package - key.String(name, value).

func (Key) Uint

func (k Key) Uint(v uint) KeyValue

Uint creates a KeyValue instance with either a UINT32 or a UINT64 Value, depending on whether the uint type is 32 or 64 bits wide.

If creating both key and a uint value at the same time, then instead of calling Key(name).Uint(value) consider using a convenience function provided by the api/key package - key.Uint(name, value).

func (Key) Uint32

func (k Key) Uint32(v uint32) KeyValue

Uint32 creates a KeyValue instance with a UINT32 Value.

If creating both key and a uint32 value at the same time, then instead of calling Key(name).Uint32(value) consider using a convenience function provided by the api/key package - key.Uint32(name, value).

func (Key) Uint64

func (k Key) Uint64(v uint64) KeyValue

Uint64 creates a KeyValue instance with a UINT64 Value.

If creating both key and a uint64 value at the same time, then instead of calling Key(name).Uint64(value) consider using a convenience function provided by the api/key package - key.Uint64(name, value).

type KeyValue

type KeyValue struct {
	Key   Key
	Value Value
}

KeyValue holds a key and value pair.

func Any

func Any(k string, value interface{}) KeyValue

Any creates a new key-value pair instance with a passed name and automatic type inference. This is slower, and not type-safe.

func Array

func Array(k string, v interface{}) KeyValue

Array creates a new key-value pair with a passed name and a array. Only arrays of primitive type are supported.

func Bool

func Bool(k string, v bool) KeyValue

Bool creates a new key-value pair with a passed name and a bool value.

func Float32

func Float32(k string, v float32) KeyValue

Float32 creates a new key-value pair with a passed name and a float32 value.

func Float64

func Float64(k string, v float64) KeyValue

Float64 creates a new key-value pair with a passed name and a float64 value.

func Int

func Int(k string, v int) KeyValue

Int creates a new key-value pair instance with a passed name and either an int32 or an int64 value, depending on whether the int type is 32 or 64 bits wide.

func Int32

func Int32(k string, v int32) KeyValue

Int32 creates a new key-value pair with a passed name and an int32 value.

func Int64

func Int64(k string, v int64) KeyValue

Int64 creates a new key-value pair with a passed name and an int64 value.

func String

func String(k, v string) KeyValue

String creates a new key-value pair with a passed name and a string value.

func Stringer

func Stringer(k string, v fmt.Stringer) KeyValue

Stringer creates a new key-value pair with a passed name and a string value generated by the passed Stringer interface.

func Uint

func Uint(k string, v uint) KeyValue

Uint creates a new key-value pair instance with a passed name and either an uint32 or an uint64 value, depending on whether the uint type is 32 or 64 bits wide.

func Uint32

func Uint32(k string, v uint32) KeyValue

Uint32 creates a new key-value pair with a passed name and a uint32 value.

func Uint64

func Uint64(k string, v uint64) KeyValue

Uint64 creates a new key-value pair with a passed name and a uint64 value.

type MergeItererator

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

MergeIterator supports iterating over two sets of labels while eliminating duplicate values from the combined set. The first iterator value takes precedence.

func NewMergeIterator

func NewMergeIterator(s1, s2 *Set) MergeItererator

NewMergeIterator returns a MergeIterator for merging two label sets Duplicates are resolved by taking the value from the first set.

func (*MergeItererator) Label

func (m *MergeItererator) Label() KeyValue

Label returns the current value after Next() returns true.

func (*MergeItererator) Next

func (m *MergeItererator) Next() bool

Next returns true if there is another label available.

type Set

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

Set is the representation for a distinct label set. It manages an immutable set of labels, with an internal cache for storing label encodings.

This type supports the `Equivalent` method of comparison using values of type `Distinct`.

This type is used to implement: 1. Metric labels 2. Resource sets 3. Correlation map (TODO)

func EmptySet

func EmptySet() *Set

func NewSet

func NewSet(kvs ...KeyValue) Set

NewSet returns a new `Set`. See the documentation for `NewSetWithSortableFiltered` for more details.

Except for empty sets, this method adds an additional allocation compared with calls that include a `*Sortable`.

func NewSetWithSortable

func NewSetWithSortable(kvs []KeyValue, tmp *Sortable) Set

NewSetWithSortable returns a new `Set`. See the documentation for `NewSetWithSortableFiltered` for more details.

This call includes a `*Sortable` option as a memory optimization.

func (*Set) Encoded

func (l *Set) Encoded(encoder Encoder) string

Encoded returns the encoded form of this set, according to `encoder`. The result will be cached in this `*Set`.

func (*Set) Equals

func (l *Set) Equals(o *Set) bool

Equals returns true if the argument set is equivalent to this set.

func (*Set) Equivalent

func (l *Set) Equivalent() Distinct

Equivalent returns a value that may be used as a map key. The Distinct type guarantees that the result will equal the equivalent Distinct value of any label set with the same elements as this, where sets are made unique by choosing the last value in the input for any given key.

func (*Set) Filter

func (l *Set) Filter(re Filter) (Set, []KeyValue)

Filter returns a filtered copy of this `Set`. See the documentation for `NewSetWithSortableFiltered` for more details.

func (*Set) Get

func (l *Set) Get(idx int) (KeyValue, bool)

Get returns the KeyValue at ordered position `idx` in this set.

func (*Set) HasValue

func (l *Set) HasValue(k Key) bool

HasValue tests whether a key is defined in this set.

func (*Set) Iter

func (l *Set) Iter() Iterator

Iter returns an iterator for visiting the labels in this set.

func (*Set) Len

func (l *Set) Len() int

Len returns the number of labels in this set.

func (*Set) MarshalJSON

func (l *Set) MarshalJSON() ([]byte, error)

MarshalJSON returns the JSON encoding of the `*Set`.

func (*Set) ToSlice

func (l *Set) ToSlice() []KeyValue

ToSlice returns the set of labels belonging to this set, sorted, where keys appear no more than once.

func (*Set) Value

func (l *Set) Value(k Key) (Value, bool)

Value returns the value of a specified key in this set.

type Sortable

type Sortable []KeyValue

Sortable implements `sort.Interface`, used for sorting `KeyValue`. This is an exported type to support a memory optimization. A pointer to one of these is needed for the call to `sort.Stable()`, which the caller may provide in order to avoid an allocation. See `NewSetWithSortable()`.

func (*Sortable) Len

func (l *Sortable) Len() int

Len implements `sort.Interface`.

func (*Sortable) Less

func (l *Sortable) Less(i, j int) bool

Less implements `sort.Interface`.

func (*Sortable) Swap

func (l *Sortable) Swap(i, j int)

Swap implements `sort.Interface`.

type Type

type Type int

Type describes the type of the data Value holds.

const (
	INVALID Type = iota // No value.
	BOOL                // Boolean value, use AsBool() to get it.
	INT32               // 32 bit signed integral value, use AsInt32() to get it.
	INT64               // 64 bit signed integral value, use AsInt64() to get it.
	UINT32              // 32 bit unsigned integral value, use AsUint32() to get it.
	UINT64              // 64 bit unsigned integral value, use AsUint64() to get it.
	FLOAT32             // 32 bit floating point value, use AsFloat32() to get it.
	FLOAT64             // 64 bit floating point value, use AsFloat64() to get it.
	STRING              // String value, use AsString() to get it.
	ARRAY               // Array value of arbitrary type, use AsArray() to get it.
)

func (Type) String

func (i Type) String() string

type Value

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

Value represents the value part in key-value pairs.

func ArrayValue

func ArrayValue(v interface{}) Value

ArrayValue creates an ARRAY value from an array or slice. Only arrays or slices of bool, int, int32, int64, uint, uint32, uint64, float, float32, float64, or string types are allowed. Specifically, arrays and slices can not contain other arrays, slices, structs, or non-standard types. If the passed value is not an array or slice of these types an INVALID value is returned.

func BoolValue

func BoolValue(v bool) Value

BoolValue creates a BOOL Value.

func Float32Value

func Float32Value(v float32) Value

Float32Value creates a FLOAT32 Value.

func Float64Value

func Float64Value(v float64) Value

Float64Value creates a FLOAT64 Value.

func Int32Value

func Int32Value(v int32) Value

Int32Value creates an INT32 Value.

func Int64Value

func Int64Value(v int64) Value

Int64Value creates an INT64 Value.

func IntValue

func IntValue(v int) Value

IntValue creates either an INT32 or an INT64 Value, depending on whether the int type is 32 or 64 bits wide.

func StringValue

func StringValue(v string) Value

StringValue creates a STRING Value.

func Uint32Value

func Uint32Value(v uint32) Value

Uint32Value creates a UINT32 Value.

func Uint64Value

func Uint64Value(v uint64) Value

Uint64Value creates a UINT64 Value.

func UintValue

func UintValue(v uint) Value

UintValue creates either a UINT32 or a UINT64 Value, depending on whether the uint type is 32 or 64 bits wide.

func (Value) AsArray

func (v Value) AsArray() interface{}

AsArray returns the array Value as an interface{}.

func (Value) AsBool

func (v Value) AsBool() bool

AsBool returns the bool value. Make sure that the Value's type is BOOL.

func (Value) AsFloat32

func (v Value) AsFloat32() float32

AsFloat32 returns the float32 value. Make sure that the Value's type is FLOAT32.

func (Value) AsFloat64

func (v Value) AsFloat64() float64

AsFloat64 returns the float64 value. Make sure that the Value's type is FLOAT64.

func (Value) AsInt32

func (v Value) AsInt32() int32

AsInt32 returns the int32 value. Make sure that the Value's type is INT32.

func (Value) AsInt64

func (v Value) AsInt64() int64

AsInt64 returns the int64 value. Make sure that the Value's type is INT64.

func (Value) AsInterface

func (v Value) AsInterface() interface{}

AsInterface returns Value's data as interface{}.

func (Value) AsString

func (v Value) AsString() string

AsString returns the string value. Make sure that the Value's type is STRING.

func (Value) AsUint32

func (v Value) AsUint32() uint32

AsUint32 returns the uint32 value. Make sure that the Value's type is UINT32.

func (Value) AsUint64

func (v Value) AsUint64() uint64

AsUint64 returns the uint64 value. Make sure that the Value's type is UINT64.

func (Value) Emit

func (v Value) Emit() string

Emit returns a string representation of Value's data.

func (Value) MarshalJSON

func (v Value) MarshalJSON() ([]byte, error)

MarshalJSON returns the JSON encoding of the Value.

func (Value) Type

func (v Value) Type() Type

Type returns a type of the Value.