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 Go to latest Published: Mar 23, 2018 License: Apache-2.0 Imports: 16 Imported by: 0

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Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func EvaluateToDuration 

func EvaluateToDuration(e Expression, context EvaluationContext) (time.Duration, error)

EvaluateToDuration is a helper function that takes an Expression and makes it a duration.

func EvaluateToScalar 

func EvaluateToScalar(e Expression, context EvaluationContext) (float64, error)

EvaluateToScalar is a helper function that takes an Expression and makes it a scalar.

func EvaluateToSeriesList 

func EvaluateToSeriesList(e Expression, context EvaluationContext) (api.SeriesList, error)

EvaluateToSeriesList is a helper function that takes an Expression and makes it a series list.

func EvaluateToString 

func EvaluateToString(e Expression, context EvaluationContext) (string, error)

EvaluateToString is a helper function that takes an Expression and makes it a string.

func StringToDuration 

func StringToDuration(timeString string) (time.Duration, error)

StringToDuration parses strings into timesdurations by examining their suffixes.

Types

type ActualExpression 

type ActualExpression interface {
	// Evaluate the given expression.
	ActualEvaluate(context EvaluationContext) (Value, error)
	ExpressionDescription(DescriptionMode) string
}

An ActualExpression is how expressions are internally implemented by the library, but not how they should be consumed.

type Argument 

type Argument int

Argument represents an argument index

type ArgumentLengthError 

type ArgumentLengthError struct {
	Name        string
	ExpectedMin int
	ExpectedMax int
	Actual      int
}

ArgumentLengthError is a kind of error that describes when a function is given too many or too few arguments.

func (ArgumentLengthError) Error 

func (err ArgumentLengthError) Error() string

Error gives a detailed description of the error.

type ConversionError 

type ConversionError struct {
	From    string // the original data type
	To      string // the type that attempted to convert to
	Context string // a short string representation of the value
}

ConversionError represents an error converting between two items of different types.

func (ConversionError) Error 

func (e ConversionError) Error() string

Error gives a readable description of the error.

type ConversionFailure 

type ConversionFailure struct {
	From string // the original data type
	To   string // the type that it attempted to convert to
}

func (*ConversionFailure) WithContext 

func (c *ConversionFailure) WithContext(context string) ConversionError

WithContext adds enough context to make the ConversionFailure into an error.

type DescriptionMode 

type DescriptionMode interface{}

DescriptionMode indicates how the expression should be evaluated.

func StringMemoization 

func StringMemoization() DescriptionMode

StringMemoization is not for humans and intended to give a unique name to every expression

func StringName 

func StringName() DescriptionMode

StringName is for human readability and respects aliases

func StringQuery 

func StringQuery() DescriptionMode

StringQuery is for humans but ignores aliases, presenting the query as written

type DurationValue 

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

DurationValue is a duration with a (usually) human-written name.

func NewDurationValue 

func NewDurationValue(name string, duration time.Duration) DurationValue

NewDurationValue creates a duration value with the given name and duration.

func (DurationValue) ToDuration 

func (value DurationValue) ToDuration() (time.Duration, *ConversionFailure)

ToDuration is a conversion function.

func (DurationValue) ToScalar 

func (value DurationValue) ToScalar() (float64, *ConversionFailure)

ToScalar is a conversion function.

func (DurationValue) ToScalarSet 

func (value DurationValue) ToScalarSet() (ScalarSet, *ConversionFailure)

func (DurationValue) ToSeriesList 

func (value DurationValue) ToSeriesList(timerange api.Timerange) (api.SeriesList, *ConversionFailure)

ToSeriesList is a conversion function.

func (DurationValue) ToString 

func (value DurationValue) ToString() (string, *ConversionFailure)

ToString is a conversion function.

type EvaluationContext 

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

EvaluationContext holds all information relevant to executing a single query.

func (EvaluationContext) AddNote 

func (context EvaluationContext) AddNote(note string)

AddNote adds a note to the evaluation context.

func (EvaluationContext) Ctx 

func (context EvaluationContext) Ctx() context.Context

Ctx returns the underlying Context instance for the evaluation.

func (EvaluationContext) EvaluateMemoized 

func (context EvaluationContext) EvaluateMemoized(expression ActualExpression) (Value, error)

EvaluateMemoized evaluates the given ActualExpression using the memoization map internal to the context.

func (EvaluationContext) FetchLimitConsume 

func (context EvaluationContext) FetchLimitConsume(n int) error

FetchLimitConsume tries to consume the amount of resources from the limit, returning a non-nil error if this would overdraw the alloted limit.

func (EvaluationContext) MetricMetadataAPI 

func (context EvaluationContext) MetricMetadataAPI() metadata.MetricAPI

MetricMetadataAPI returns the underlying metadata.MetricAPI.

func (EvaluationContext) Notes 

func (context EvaluationContext) Notes() []string

Notes returns all notes added to the evaluation context.

func (EvaluationContext) Predicate 

func (context EvaluationContext) Predicate() predicate.Predicate

Predicate returns the underlying predicate.Predicate.

func (EvaluationContext) Profiler 

func (context EvaluationContext) Profiler() *inspect.Profiler

Profiler returns the underlying inspect.Profiler instance.

func (EvaluationContext) RegistryGetFunction 

func (context EvaluationContext) RegistryGetFunction(name string) (Function, bool)

RegistryGetFunction gets the function of the provided name, return true if the function could be found and false otherwise.

func (EvaluationContext) SampleMethod 

func (context EvaluationContext) SampleMethod() timeseries.SampleMethod

SampleMethod returns the underlying timeseries.SampleMethod.

func (EvaluationContext) Timerange 

func (context EvaluationContext) Timerange() api.Timerange

Timerange returns the underlying api.Timerange.

func (EvaluationContext) TimeseriesStorageAPI 

func (context EvaluationContext) TimeseriesStorageAPI() timeseries.StorageAPI

TimeseriesStorageAPI returns the underlying timeseries.StorageAPI.

func (EvaluationContext) WithAdditionalConstraint 

func (context EvaluationContext) WithAdditionalConstraint(p predicate.Predicate) EvaluationContext

WithAdditionalConstraint return a new copy of the evaluation context with a distinct memoization map.

func (EvaluationContext) WithTimerange 

func (context EvaluationContext) WithTimerange(t api.Timerange) EvaluationContext

WithTimerange duplicates the EvaluationContext but with a new timerange.

type EvaluationContextBuilder 

type EvaluationContextBuilder struct {
	TimeseriesStorageAPI timeseries.StorageAPI   // Backend to fetch data from
	MetricMetadataAPI    metadata.MetricAPI      // Api to obtain metadata from
	Registry             Registry                // Registry stores functions
	SampleMethod         timeseries.SampleMethod // SampleMethod to use when up/downsampling to match the requested resolution
	FetchLimit           FetchCounter            // A limit on the number of fetches which may be performed
	Profiler             *inspect.Profiler       // A profiler pointer
	EvaluationNotes      *EvaluationNotes        // Debug + numerical notes that can be added during evaluation
	Ctx                  context.Context

	// These may be changed in sub-contexts while evaluating the query.
	Timerange api.Timerange       // Timerange to fetch data from
	Predicate predicate.Predicate // Predicate to apply to TagSets prior to fetching
}

An EvaluationContextBuilder is used to create an EvaluationContext because the EvaluationContext's fields are private to prevent accidental modification.

func (EvaluationContextBuilder) Build 

func (builder EvaluationContextBuilder) Build() EvaluationContext

Build creates an evaluation context from the provided builder.

type EvaluationNotes 

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

EvaluationNotes holds notes that were recorded during evaluation.

func (*EvaluationNotes) AddNote 

func (notes *EvaluationNotes) AddNote(note string)

AddNote adds a new note to the collection in a threadsafe manner.

func (*EvaluationNotes) Notes 

func (notes *EvaluationNotes) Notes() []string

Notes returns the current collection of notes in a threadsafe manner.

type Expression 

type Expression interface {
	Evaluate(context EvaluationContext) (Value, error)
	ExpressionDescription(DescriptionMode) string
}

Expression is a piece of code, which can be evaluated in a given EvaluationContext. EvaluationContext must never be changed in an Evaluate().

If an Expression returns a SeriesList, its timerange must match the context's timerange exactly.

func Memoize 

func Memoize(expression ActualExpression) Expression

Memoize takes an ordinary actual expression and turns it into a memoized expression.

type FetchCounter 

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

FetchCounter is used to count the number of fetches remaining in a thread-safe manner.

func NewFetchCounter 

func NewFetchCounter(n int) FetchCounter

NewFetchCounter creates a FetchCounter with n as the limit.

func (FetchCounter) Consume 

func (c FetchCounter) Consume(n int) error

Consume decrements the internal counter and returns whether the result is at least 0. It does so in a threadsafe manner.

func (FetchCounter) Current 

func (c FetchCounter) Current() int

Current returns the current number of fetches remaining for the counter.

func (FetchCounter) Limit 

func (c FetchCounter) Limit() int

Limit returns the max # of fetches allowed by this counter.

type Function 

type Function interface {
	Run(EvaluationContext, []Expression, Groups) (Value, error)
	Name() string
}

The Function interface defines a metric function. It is given several (unevaluated) expressions as input, and evaluates to a Value.

type Groups 

type Groups struct {
	List      []string // the tags to group by
	Collapses bool     // whether to "collapse by" instead of "group by"
}

Groups holds grouping information - which tags to group by (if any), and whether to `collapse` (Collapses = true) or `group` (Collapses = false)

type LimitError 

type LimitError interface {
	Actual() interface{} // actual from the system which triggered this error.
	Limit() interface{}  // configured limit
	error
}

LimitError is returned if an error occurs where limits are surpassed.

func NewLimitError 

func NewLimitError(message string, actual interface{}, limit interface{}) LimitError

NewLimitError uses its parameters to create a LimitError.

type LiteralExpression 

type LiteralExpression interface {
	Literal() interface{}
}

A LiteralExpression is an expression that holds a literal value. Returning `nil` indicates that your particular instance doesn't actually hold any literal value.

type MetricFunction 

type MetricFunction struct {
	FunctionName  string // Name is the name of the function, used in its registration.
	MinArguments  int    // MinArguments is the minimum number of arguments the function allows.
	MaxArguments  int    // MaxArguments is the maximum number of arguments the function allows. -1 indicates an unlimited number.
	AllowsGroupBy bool   // Whether the function allows a 'group by' clause.
	Compute       func(EvaluationContext, []Expression, Groups) (Value, error)
	Widen         func(WidestMode, []Expression) time.Time // Optional; returns new Earliest
}

MetricFunction holds a generic function object with information about its parameters.

func MakeFunction 

func MakeFunction(name string, function interface{}, options ...Option) MetricFunction

MakeFunction is a convenient way to use type-safe functions to construct MetricFunctions without manually checking parameters.

func (MetricFunction) Name 

func (f MetricFunction) Name() string

Name returns the MetricFunction's name.

func (MetricFunction) Run 

func (f MetricFunction) Run(context EvaluationContext, arguments []Expression, groups Groups) (Value, error)

Run evaluates the given MetricFunction on its arguments. It performs error-checking against the supplies number of arguments and/or group-by clause.

type Option 

type Option struct {
	Name  OptionName  // Name identifies the option type
	Value interface{} // Value is the value associated with the option
}

An Option is an annotation used to add extra functionality to the generated MetricFunction.

type OptionName 

type OptionName int

An OptionName identifies an option passed to MakeFunction 

const (
	InvalidOption OptionName = iota // InvalidOption represents an invalid option
	WidenBy                         // WidenBy indicates that the given duration Argument index, or the number of Slots should be used to extend the timerange in the query into the past by the given amount.
	ShiftBy                         // ShiftBy indicates that the given duration Argument index, or the number of Slots should be used to shift the timerange in the query (positive is forward in time into the future, negative is backward in time to the past)
)

func (OptionName) String 

func (n OptionName) String() string

String makes the option name human-readable.

type Registry 

type Registry interface {
	GetFunction(string) (Function, bool) // returns an instance of a Function
	All() []string                       // all the registered functions
}

The Registry interface defines a mapping from names to Functions and provides a way to get the full list of functions defined.

type ScalarSet 

type ScalarSet []TaggedScalar

func EvaluateToScalarSet 

func EvaluateToScalarSet(e Expression, context EvaluationContext) (ScalarSet, error)

EvaluateToScalarSet is a helper function that takes an Expression and makes it a scalar set.

func (ScalarSet) ToDuration 

func (set ScalarSet) ToDuration() (time.Duration, *ConversionFailure)

func (ScalarSet) ToScalar 

func (set ScalarSet) ToScalar() (float64, *ConversionFailure)

func (ScalarSet) ToScalarSet 

func (set ScalarSet) ToScalarSet() (ScalarSet, *ConversionFailure)

func (ScalarSet) ToSeriesList 

func (set ScalarSet) ToSeriesList(timerange api.Timerange) (api.SeriesList, *ConversionFailure)

func (ScalarSet) ToString 

func (set ScalarSet) ToString() (string, *ConversionFailure)

type ScalarValue 

type ScalarValue float64

A ScalarValue holds a float and can be converted to a serieslist

func (ScalarValue) ToDuration 

func (value ScalarValue) ToDuration() (time.Duration, *ConversionFailure)

ToDuration is a conversion function. Scalars cannot be converted to durations.

func (ScalarValue) ToScalar 

func (value ScalarValue) ToScalar() (float64, *ConversionFailure)

ToScalar is a conversion function.

func (ScalarValue) ToScalarSet 

func (value ScalarValue) ToScalarSet() (ScalarSet, *ConversionFailure)

ToScalarSet is a conversion function.

func (ScalarValue) ToSeriesList 

func (value ScalarValue) ToSeriesList(timerange api.Timerange) (api.SeriesList, *ConversionFailure)

ToSeriesList is a conversion function. The scalar becomes a constant value for the timerange.

func (ScalarValue) ToString 

func (value ScalarValue) ToString() (string, *ConversionFailure)

ToString is a conversion function. Numbers become formatted.

type SeriesListValue 

type SeriesListValue api.SeriesList

A SeriesListValue holds a SeriesList.

func (SeriesListValue) ToDuration 

func (list SeriesListValue) ToDuration() (time.Duration, *ConversionFailure)

ToDuration is a conversion function to implement the Value interface.

func (SeriesListValue) ToScalar 

func (list SeriesListValue) ToScalar() (float64, *ConversionFailure)

ToScalar is a conversion function to implement the Value interface.

func (SeriesListValue) ToScalarSet 

func (list SeriesListValue) ToScalarSet() (ScalarSet, *ConversionFailure)

ToScalarSet is a conversion function to implement the Value interface.

func (SeriesListValue) ToSeriesList 

func (list SeriesListValue) ToSeriesList(time api.Timerange) (api.SeriesList, *ConversionFailure)

ToSeriesList is an identity function that allows SeriesList to implement the Value interface.

func (SeriesListValue) ToString 

func (list SeriesListValue) ToString() (string, *ConversionFailure)

ToString is a conversion function to implement the Value interface.

type Slot 

type Slot int

Slot represents a number of slots

type StringMemoizationMode 

type StringMemoizationMode struct{}

type StringNameMode 

type StringNameMode struct{}

type StringQueryMode 

type StringQueryMode struct{}

type StringValue 

type StringValue string

A StringValue holds a string

func (StringValue) ToDuration 

func (value StringValue) ToDuration() (time.Duration, *ConversionFailure)

ToDuration is a conversion function.

func (StringValue) ToScalar 

func (value StringValue) ToScalar() (float64, *ConversionFailure)

ToScalar is a conversion function.

func (StringValue) ToScalarSet 

func (value StringValue) ToScalarSet() (ScalarSet, *ConversionFailure)

ToScalarSet is a conversion function.

func (StringValue) ToSeriesList 

func (value StringValue) ToSeriesList(time api.Timerange) (api.SeriesList, *ConversionFailure)

ToSeriesList is a conversion function.

func (StringValue) ToString 

func (value StringValue) ToString() (string, *ConversionFailure)

ToString is a conversion function.

type TaggedScalar 

type TaggedScalar struct {
	TagSet api.TagSet
	Value  float64
}

func (TaggedScalar) MarshalJSON 

func (ts TaggedScalar) MarshalJSON() ([]byte, error)

MarshalJSON for TaggedScalar marshals NaN or infinity to null.

type Value 

type Value interface {
	ToSeriesList(api.Timerange) (api.SeriesList, *ConversionFailure)
	ToString() (string, *ConversionFailure)
	ToScalar() (float64, *ConversionFailure)
	ToScalarSet() (ScalarSet, *ConversionFailure)
	ToDuration() (time.Duration, *ConversionFailure)
}

Value is the result of evaluating an expression. They can be floating point values, strings, or series lists.

func EvaluateMany 

func EvaluateMany(context EvaluationContext, expressions []Expression) ([]Value, error)

EvaluateMany evaluates a list of expressions using a single EvaluationContext. If any evaluation errors, EvaluateMany will propagate that error. The resulting values will be in the order corresponding to the provided expressions.

type WidestMode 

type WidestMode struct {
	Registry   Registry
	Current    time.Time
	Earliest   *time.Time
	Resolution time.Duration
	Mutex      *sync.Mutex
}

func (*WidestMode) AddTime 

func (w *WidestMode) AddTime(t time.Time)

Source Files

View all Source files

Directories

Path Synopsis
builtin
aggregate
filter
forecast
join
summary
tag
transform
Package transform contains all the logic to parse and execute queries against the underlying metric system.
 Package transform contains all the logic to parse and execute queries against the underlying metric system.

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