Documentation
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Overview ¶
Package metrics implements the Beam metrics API, described at http://s.apache.org/beam-metrics-api
Metrics in the Beam model are uniquely identified by a namespace, a name, and the PTransform context in which they are used. Further, they are reported as a delta against the bundle being processed, so that overcounting doesn't occur if a bundle needs to be retried. Each metric is scoped to their bundle, and ptransform.
Cells (or metric cells) are defined for each Beam model metric type, and the serve as concurrency safe storage of a given metric's values. Proxys are exported values representing the metric, for use in user ptransform code. They don't retain their cells, since they don't have the context to be able to store them for export back to the pipeline runner.
Metric cells aren't initialized until their first mutation, which follows from the Beam model design, where metrics are only sent for a bundle if they have changed. This is particularly convenient for distributions which means their min and max fields can be set to the first value on creation rather than have some marker of uninitialized state, which would otherwise need to be checked for on every update.
Metric values are implemented as lightweight proxies of the user provided namespace and name. This allows them to be declared globally, and used in any ParDo. Further, as per the design, they can be declared dynamically at runtime.
To handle reporting deltas on the metrics by bundle, metrics are keyed by bundleID,PTransformID,namespace, and name, so metrics that are identical except for bundles are treated as distinct, effectively providing per bundle deltas, since a new value cell is used per bundle.
Index ¶
- func Clear()
- func ClearBundleData(b string)
- func DumpToLog(ctx context.Context)
- func DumpToOut()
- func SetBundleID(ctx context.Context, id string) context.Context
- func SetPTransformID(ctx context.Context, id string) context.Context
- func ToProto(b, pt string) []*fnexecution_v1.Metrics_User
- type Counter
- type Distribution
- type Gauge
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Clear ¶
func Clear()
Clear resets all storage associated with metrics for tests. Calling this in pipeline code leads to inaccurate metrics.
func ClearBundleData ¶
func ClearBundleData(b string)
ClearBundleData removes stored references associated with a given bundle, so it can be garbage collected.
func DumpToLog ¶
DumpToLog is a debugging function that outputs all metrics available locally to beam.Log.
func DumpToOut ¶
func DumpToOut()
DumpToOut is a debugging function that outputs all metrics available locally to std out.
func SetBundleID ¶
SetBundleID sets the id of the current Bundle.
func SetPTransformID ¶
SetPTransformID sets the id of the current PTransform.
func ToProto ¶
func ToProto(b, pt string) []*fnexecution_v1.Metrics_User
ToProto exports all collected metrics for the given BundleID and PTransform ID pair.
Types ¶
type Counter ¶
type Counter struct {
// contains filtered or unexported fields
}
Counter is a simple counter for incrementing and decrementing a value.
func NewCounter ¶
NewCounter returns the Counter with the given namespace and name.
type Distribution ¶
type Distribution struct {
// contains filtered or unexported fields
}
Distribution is a simple distribution of values.
func NewDistribution ¶
func NewDistribution(ns, n string) Distribution
NewDistribution returns the Distribution with the given namespace and name.
func (Distribution) String ¶
func (m Distribution) String() string
type Gauge ¶
type Gauge struct {
// contains filtered or unexported fields
}
Gauge is a time, value pair metric.
Source Files