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//! Metrics Export use crate::sdk::resource::Resource; use crate::{ labels, metrics::{Descriptor, InstrumentKind, Number, Result}, }; use std::any::Any; use std::fmt; use std::sync::Arc; use std::time::SystemTime; mod aggregation; pub mod stdout; pub use aggregation::{ Buckets, Count, Histogram, LastValue, Max, Min, MinMaxSumCount, Points, Sum, }; pub use stdout::stdout; /// Processor is responsible for deciding which kind of aggregation to use (via /// `aggregation_selector`), gathering exported results from the SDK during /// collection, and deciding over which dimensions to group the exported data. /// /// The SDK supports binding only one of these interfaces, as it has the sole /// responsibility of determining which Aggregator to use for each record. /// /// The embedded AggregatorSelector interface is called (concurrently) in /// instrumentation context to select the appropriate Aggregator for an /// instrument. pub trait Processor: fmt::Debug { /// AggregatorSelector is responsible for selecting the /// concrete type of Aggregator used for a metric in the SDK. /// /// This may be a static decision based on fields of the /// Descriptor, or it could use an external configuration /// source to customize the treatment of each metric /// instrument. /// /// The result from AggregatorSelector.AggregatorFor should be /// the same type for a given Descriptor or else nil. The same /// type should be returned for a given descriptor, because /// Aggregators only know how to Merge with their own type. If /// the result is nil, the metric instrument will be disabled. /// /// Note that the SDK only calls AggregatorFor when new records /// require an Aggregator. This does not provide a way to /// disable metrics with active records. fn aggregation_selector(&self) -> &dyn AggregatorSelector; } /// A locked processor. /// /// The `Process` method is called during collection in a single-threaded /// context from the SDK, after the aggregator is checkpointed, allowing the /// processor to build the set of metrics currently being exported. pub trait LockedProcessor { /// Process is called by the SDK once per internal record, passing the export /// Accumulation (a Descriptor, the corresponding Labels, and the checkpointed /// Aggregator). /// /// The Context argument originates from the controller that orchestrates /// collection. fn process(&mut self, accumulation: Accumulation<'_>) -> Result<()>; } /// AggregatorSelector supports selecting the kind of `Aggregator` to use at /// runtime for a specific metric instrument. pub trait AggregatorSelector: fmt::Debug { /// This allocates a variable number of aggregators of a kind suitable for /// the requested export. /// /// When the call returns `None`, the metric instrument is explicitly disabled. /// /// This must return a consistent type to avoid confusion in later stages of /// the metrics export process, e.g., when merging or checkpointing /// aggregators for a specific instrument. /// /// This call should not block. fn aggregator_for(&self, descriptor: &Descriptor) -> Option<Arc<dyn Aggregator + Send + Sync>>; } /// The interface used by a `Controller` to coordinate the `Processor` with /// `Accumulator`(s) and `Exporter`(s). The `start_collection` and /// `finish_collection` methods start and finish a collection interval. /// `Controller`s call the `Accumulator`(s) during collection to process /// `Accumulation`s. pub trait Checkpointer: LockedProcessor { /// A checkpoint of the current data set. This may be called before and after /// collection. The implementation is required to return the same value /// throughout its lifetime. fn checkpoint_set(&mut self) -> &mut dyn CheckpointSet; /// Logic to be run at the start of a collection interval. fn start_collection(&mut self); /// Cleanup logic or other behavior that needs to be run after a collection /// interval is complete. fn finish_collection(&mut self) -> Result<()>; } /// Aggregator implements a specific aggregation behavior, i.e., a behavior to /// track a sequence of updates to an instrument. Sum-only instruments commonly /// use a simple Sum aggregator, but for the distribution instruments /// (ValueRecorder, ValueObserver) there are a number of possible aggregators /// with different cost and accuracy tradeoffs. /// /// Note that any Aggregator may be attached to any instrument--this is the /// result of the OpenTelemetry API/SDK separation. It is possible to attach a /// Sum aggregator to a ValueRecorder instrument or a MinMaxSumCount aggregator /// to a Counter instrument. pub trait Aggregator: fmt::Debug { /// Update receives a new measured value and incorporates it into the /// aggregation. Update calls may be called concurrently. /// /// `Descriptor::number_kind` should be consulted to determine whether the /// provided number is an `i64`, `u64` or `f64`. /// /// The current Context could be inspected for a `Baggage` or /// `SpanContext`. fn update(&self, number: &Number, descriptor: &Descriptor) -> Result<()>; /// This method is called during collection to finish one period of aggregation /// by atomically saving the currently-updating state into the argument /// Aggregator. /// /// `synchronized_move` is called concurrently with `update`. These two methods /// must be synchronized with respect to each other, for correctness. /// /// This method will return an `InconsistentAggregator` error if this /// `Aggregator` cannot be copied into the destination due to an incompatible /// type. /// /// This call has no `Context` argument because it is expected to perform only /// computation. fn synchronized_move( &self, destination: &Arc<dyn Aggregator + Send + Sync>, descriptor: &Descriptor, ) -> Result<()>; /// This combines the checkpointed state from the argument `Aggregator` into this /// `Aggregator`. `merge` is not synchronized with respect to `update` or /// `synchronized_move`. /// /// The owner of an `Aggregator` being merged is responsible for synchronization /// of both `Aggregator` states. fn merge(&self, other: &(dyn Aggregator + Send + Sync), descriptor: &Descriptor) -> Result<()>; /// Returns the implementing aggregator as `Any` for downcasting. fn as_any(&self) -> &dyn Any; } /// An optional interface implemented by some Aggregators. An Aggregator must /// support `subtract()` in order to be configured for a Precomputed-Sum /// instrument (SumObserver, UpDownSumObserver) using a DeltaExporter. pub trait Subtractor { /// Subtract subtracts the `operand` from this Aggregator and outputs the value /// in `result`. fn subtract( &self, operand: &(dyn Aggregator + Send + Sync), result: &(dyn Aggregator + Send + Sync), descriptor: &Descriptor, ) -> Result<()>; } /// Exporter handles presentation of the checkpoint of aggregate metrics. This /// is the final stage of a metrics export pipeline, where metric data are /// formatted for a specific system. pub trait Exporter: ExportKindFor { /// Export is called immediately after completing a collection pass in the SDK. /// /// The CheckpointSet interface refers to the Processor that just completed /// collection. fn export(&self, checkpoint_set: &mut dyn CheckpointSet) -> Result<()>; } /// ExportKindSelector is a sub-interface of Exporter used to indicate /// whether the Processor should compute Delta or Cumulative /// Aggregations. pub trait ExportKindFor: fmt::Debug { /// Determines the correct `ExportKind` that should be used when exporting data /// for the given metric instrument. fn export_kind_for(&self, descriptor: &Descriptor) -> ExportKind; } /// CheckpointSet allows a controller to access a complete checkpoint of /// aggregated metrics from the Processor. This is passed to the `Exporter` /// which may then use `try_for_each` to iterate over the collection of /// aggregated metrics. pub trait CheckpointSet: fmt::Debug { /// This iterates over aggregated checkpoints for all metrics that were updated /// during the last collection period. Each aggregated checkpoint returned by /// the function parameter may return an error. /// /// The `ExportKindSelector` argument is used to determine whether the `Record` /// is computed using delta or cumulative aggregation. /// /// ForEach tolerates `MetricsError::NoData` silently, as this is expected from /// the Meter implementation. Any other kind of error will immediately halt and /// return the error to the caller. fn try_for_each( &mut self, export_selector: &dyn ExportKindFor, f: &mut dyn FnMut(&Record<'_>) -> Result<()>, ) -> Result<()>; } /// Allows `Accumulator` implementations to construct new `Accumulation`s to /// send to `Processor`s. The `Descriptor`, `Labels`, `Resource`, and /// `Aggregator` represent aggregate metric events received over a single /// collection period. pub fn accumulation<'a>( descriptor: &'a Descriptor, labels: &'a labels::LabelSet, resource: &'a Resource, aggregator: &'a Arc<dyn Aggregator + Send + Sync>, ) -> Accumulation<'a> { Accumulation::new(descriptor, labels, resource, aggregator) } /// Allows `Processor` implementations to construct export records. The /// `Descriptor`, `Labels`, and `Aggregator` represent aggregate metric events /// received over a single collection period. pub fn record<'a>( descriptor: &'a Descriptor, labels: &'a labels::LabelSet, resource: &'a Resource, aggregator: Option<&'a Arc<dyn Aggregator + Send + Sync>>, start: SystemTime, end: SystemTime, ) -> Record<'a> { Record { metadata: Metadata::new(descriptor, labels, resource), aggregator, start, end, } } impl Record<'_> { /// The aggregator for this metric pub fn aggregator(&self) -> Option<&Arc<dyn Aggregator + Send + Sync>> { self.aggregator } } /// A container for the common elements for exported metric data that are shared /// by the `Accumulator`->`Processor` and `Processor`->`Exporter` steps. #[derive(Debug)] pub struct Metadata<'a> { descriptor: &'a Descriptor, labels: &'a labels::LabelSet, resource: &'a Resource, } impl<'a> Metadata<'a> { /// Create a new `Metadata` instance. pub fn new( descriptor: &'a Descriptor, labels: &'a labels::LabelSet, resource: &'a Resource, ) -> Self { { Metadata { descriptor, labels, resource, } } } /// A description of the metric instrument being exported. pub fn descriptor(&self) -> &Descriptor { self.descriptor } /// The labels associated with the instrument and the aggregated data. pub fn labels(&self) -> &labels::LabelSet { self.labels } /// Common attributes that apply to this metric event. pub fn resource(&self) -> &Resource { self.resource } } /// A container for the exported data for a single metric instrument and label /// set, as prepared by the `Processor` for the `Exporter`. This includes the /// effective start and end time for the aggregation. #[derive(Debug)] pub struct Record<'a> { metadata: Metadata<'a>, aggregator: Option<&'a Arc<dyn Aggregator + Send + Sync>>, start: SystemTime, end: SystemTime, } impl Record<'_> { /// A description of the metric instrument being exported. pub fn descriptor(&self) -> &Descriptor { self.metadata.descriptor } /// The labels associated with the instrument and the aggregated data. pub fn labels(&self) -> &labels::LabelSet { self.metadata.labels } /// Common attributes that apply to this metric event. pub fn resource(&self) -> &Resource { self.metadata.resource } /// The start time of the interval covered by this aggregation. pub fn start_time(&self) -> &SystemTime { &self.start } /// The end time of the interval covered by this aggregation. pub fn end_time(&self) -> &SystemTime { &self.end } } /// A container for the exported data for a single metric instrument and label /// set, as prepared by an `Accumulator` for the `Processor`. #[derive(Debug)] pub struct Accumulation<'a> { metadata: Metadata<'a>, aggregator: &'a Arc<dyn Aggregator + Send + Sync>, } impl<'a> Accumulation<'a> { /// Create a new `Record` instance. pub fn new( descriptor: &'a Descriptor, labels: &'a labels::LabelSet, resource: &'a Resource, aggregator: &'a Arc<dyn Aggregator + Send + Sync>, ) -> Self { Accumulation { metadata: Metadata::new(descriptor, labels, resource), aggregator, } } /// A description of the metric instrument being exported. pub fn descriptor(&self) -> &Descriptor { self.metadata.descriptor } /// The labels associated with the instrument and the aggregated data. pub fn labels(&self) -> &labels::LabelSet { self.metadata.labels } /// Common attributes that apply to this metric event. pub fn resource(&self) -> &Resource { self.metadata.resource } /// The checkpointed aggregator for this metric. pub fn aggregator(&self) -> &Arc<dyn Aggregator + Send + Sync> { self.aggregator } } /// Indicates the kind of data exported by an exporter. /// These bits may be OR-d together when multiple exporters are in use. #[derive(Clone, Debug)] pub enum ExportKind { /// Indicates that the `Exporter` expects a cumulative `Aggregation`. Cumulative = 1, /// Indicates that the `Exporter` expects a delta `Aggregation`. Delta = 2, } /// Strategies for selecting which export kind is used for an instrument. #[derive(Debug, Clone)] pub enum ExportKindSelector { /// A selector that always returns [`ExportKind::Cumulative`]. Cumulative, /// A selector that always returns [`ExportKind::Delta`]. Delta, /// A selector that returns cumulative or delta based on a given instrument /// kind. Stateless, } impl ExportKind { /// Tests whether `kind` includes a specific kind of exporter. pub fn includes(&self, has: &ExportKind) -> bool { (self.clone() as u32) & (has.clone() as u32) != 0 } /// Returns whether an exporter of this kind requires memory to export correctly. pub fn memory_required(&self, kind: &InstrumentKind) -> bool { match kind { InstrumentKind::ValueRecorder | InstrumentKind::ValueObserver | InstrumentKind::Counter | InstrumentKind::UpDownCounter => { // Delta-oriented instruments: self.includes(&ExportKind::Cumulative) } InstrumentKind::SumObserver | InstrumentKind::UpDownSumObserver => { // Cumulative-oriented instruments: self.includes(&ExportKind::Delta) } } } } impl ExportKindFor for ExportKindSelector { fn export_kind_for(&self, descriptor: &Descriptor) -> ExportKind { match self { ExportKindSelector::Cumulative => ExportKind::Cumulative, ExportKindSelector::Delta => ExportKind::Delta, ExportKindSelector::Stateless => { if descriptor.instrument_kind().precomputed_sum() { ExportKind::Cumulative } else { ExportKind::Delta } } } } }