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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func EventValues ¶
func EventValues(e *epb.Event, mds MetadataStore) []*spb.Summary_Value
EventValues converts an on-disk event to the summary values that it represents, applying compatibility transformations. It updates the MetadataStore with any new summary metadata, and may read from it to determine how to transform summary data. The input event may be mutated.
Types ¶
type EagerReservoir ¶
type EagerReservoir interface {
// Offer accepts a record from the stream and either inserts it into
// the reservoir or discards it (with the caveat that the most recent
// record is always kept).
Offer(value StepIndexed)
// Sample takes a simple random sample from the non-preempted records
// of the stream read so far, chosen uniformly among samples that
// include the most recent record. The returned buffer is owned by the
// caller.
Sample() []StepIndexed
// Last returns the most recent record, or nil if no records have yet
// been offered.
Last() StepIndexed
}
EagerReservoir describes the contract for a naive reservoir sampling algorithm (data structure) over StepIndexed values. An EagerReservoir must inspect every record in the stream. Preemption occurs implicitly whenever the Step value of a record does not increase.
func NewEagerReservoir ¶
func NewEagerReservoir(capacity uint64) EagerReservoir
NewEagerReservoir creates an EagerReservoir with the given capacity. The reservoir can hold up to capacity elements losslessly, and will start downsampling after that many.
type MetadataStore ¶
type MetadataStore map[string]*spb.SummaryMetadata
A MetadataStore holds the initial SummaryMetadata seen for each tag within a single run. Keys are tag names; the run is implicit.
type Step ¶
type Step int64
A Step represents a strictly monotonically increasing step value. It is stored as an int64, but must be non-negative.
type StepIndexed ¶
type StepIndexed interface {
// Step returns the step for this value, which must be non-negative.
// See docs for StepIndexed for a description of steps.
Step() Step
}
StepIndexed describes values that are uniquely indexed by "step", a non-negative integer that increases with time (potentially non-consecutively).
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