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//! High-speed metrics collection library. //! //! `metrics` provides a generalized metrics collection library targeted at users who want to log //! metrics at high volume and high speed. //! //! # Design //! //! The library follows a pattern of "senders" and a "receiver." //! //! Callers create a [`Receiver`], which acts as a registry for all metrics that flow through it. //! It allows creating new sinks as well as controllers, both necessary to push in and pull out //! metrics from the system. It also manages background resources necessary for the registry to //! operate. //! //! Once a [`Receiver`] is created, callers can either create a [`Sink`] for sending metrics, or a //! [`Controller`] for getting metrics out. //! //! A [`Sink`] can be cheaply cloned, and offers convenience methods for getting the current time //! as well as getting direct handles to a given metric. This allows users to either work with the //! fuller API exposed by [`Sink`] or to take a compositional approach and embed fields that //! represent each particular metric to be sent. //! //! A [`Controller`] provides both a synchronous and asynchronous snapshotting interface, which is //! [`metrics-core`][metrics_core] compatible for exporting. This allows flexibility in //! integration amongst traditional single-threaded or hand-rolled multi-threaded applications and //! the emerging asynchronous Rust ecosystem. //! //! # Performance //! //! Users can expect to be able to send tens of millions of samples per second, with ingest //! latencies at roughly 65-70ns at p50, and 250ns at p99. Depending on the workload -- counters //! vs histograms -- latencies may be even lower, as counters and gauges are markedly faster to //! update than histograms. Concurrent updates of the same metric will also cause natural //! contention and lower the throughput/increase the latency of ingestion. //! //! # Metrics //! //! Counters, gauges, and histograms are supported, and follow the definitions outlined in //! [`metrics-core`][metrics_core]. //! //! Here's a simple example of creating a receiver and working with a sink: //! //! ``` //! # extern crate metrics; //! use metrics::Receiver; //! use std::{thread, time::Duration}; //! let receiver = Receiver::builder().build().expect("failed to create receiver"); //! let mut sink = receiver.get_sink(); //! //! // We can update a counter. Counters are monotonic, unsigned integers that start at 0 and //! // increase over time. //! sink.record_count("widgets", 5); //! //! // We can update a gauge. Gauges are signed, and hold on to the last value they were updated //! // to, so you need to track the overall value on your own. //! sink.record_gauge("red_balloons", 99); //! //! // We can update a timing histogram. For timing, we're using the built-in `Sink::now` method //! // which utilizes a high-speed internal clock. This method returns the time in nanoseconds, so //! // we get great resolution, but giving the time in nanoseconds isn't required! If you want to //! // send it in another unit, that's fine, but just pay attention to that fact when viewing and //! // using those metrics once exported. We also support passing `Instant` values -- both `start` //! // and `end` need to be the same type, though! -- and we'll take the nanosecond output of that. //! let start = sink.now(); //! thread::sleep(Duration::from_millis(10)); //! let end = sink.now(); //! sink.record_timing("db.queries.select_products_ns", start, end); //! //! // Finally, we can update a value histogram. Technically speaking, value histograms aren't //! // fundamentally different from timing histograms. If you use a timing histogram, we do the //! // math for you of getting the time difference, but other than that, identical under the hood. //! let row_count = 46; //! sink.record_value("db.queries.select_products_num_rows", row_count); //! ``` //! //! # Scopes //! //! Metrics can be scoped, not unlike loggers, at the [`Sink`] level. This allows sinks to easily //! nest themselves without callers ever needing to care about where they're located. //! //! This feature is a simpler approach to tagging: while not as semantically rich, it provides the //! level of detail necessary to distinguish a single metric between multiple callsites. //! //! For example, after getting a [`Sink`] from the [`Receiver`], we can easily nest ourselves under //! the root scope and then send some metrics: //! //! ``` //! # extern crate metrics; //! use metrics::Receiver; //! let receiver = Receiver::builder().build().expect("failed to create receiver"); //! //! // This sink has no scope aka the root scope. The metric will just end up as "widgets". //! let mut root_sink = receiver.get_sink(); //! root_sink.record_count("widgets", 42); //! //! // This sink is under the "secret" scope. Since we derived ourselves from the root scope, //! // we're not nested under anything, but our metric name will end up being "secret.widgets". //! let mut scoped_sink = root_sink.scoped("secret"); //! scoped_sink.record_count("widgets", 42); //! //! // This sink is under the "supersecret" scope, but we're also nested! The metric name for this //! // sample will end up being "secret.supersecret.widget". //! let mut scoped_sink_two = scoped_sink.scoped("supersecret"); //! scoped_sink_two.record_count("widgets", 42); //! //! // Sinks retain their scope even when cloned, so the metric name will be the same as above. //! let mut cloned_sink = scoped_sink_two.clone(); //! cloned_sink.record_count("widgets", 42); //! //! // This sink will be nested two levels deeper than its parent by using a slightly different //! // input scope: scope can be a single string, or multiple strings, which is interpreted as //! // nesting N levels deep. //! // //! // This metric name will end up being "super.secret.ultra.special.widgets". //! let mut scoped_sink_three = scoped_sink.scoped(&["super", "secret", "ultra", "special"]); //! scoped_sink_two.record_count("widgets", 42); //! ``` //! //! # Snapshots //! //! Naturally, we need a way to get the metrics out of the system, which is where snapshots come //! into play. By utilizing a [`Controller`], we can take a snapshot of the current metrics in the //! registry, and then output them to any desired system/interface by utilizing //! [`Recorder`](metrics_core::Recorder). A number of pre-baked recorders (which only concern //! themselves with formatting the data) and exporters (which take the formatted data and either //! serve it up, such as exposing an HTTP endpoint, or write it somewhere, like stdout) are //! available, some of which are exposed by this crate. //! //! Let's take an example of writing out our metrics in a yaml-like format, writing them via //! `log!`: //! ``` //! # extern crate metrics; //! use metrics::{Receiver, recorders::TextRecorder, exporters::LogExporter}; //! use log::Level; //! use std::{thread, time::Duration}; //! let receiver = Receiver::builder().build().expect("failed to create receiver"); //! let mut sink = receiver.get_sink(); //! //! // We can update a counter. Counters are monotonic, unsigned integers that start at 0 and //! // increase over time. //! // Take some measurements, similar to what we had in other examples: //! sink.record_count("widgets", 5); //! sink.record_gauge("red_balloons", 99); //! //! let start = sink.now(); //! thread::sleep(Duration::from_millis(10)); //! let end = sink.now(); //! sink.record_timing("db.queries.select_products_ns", start, end); //! sink.record_timing("db.gizmo_query", start, end); //! //! let num_rows = 46; //! sink.record_value("db.queries.select_products_num_rows", num_rows); //! //! // Now create our exporter/recorder configuration, and wire it up. //! let exporter = LogExporter::new(receiver.get_controller(), TextRecorder::new(), Level::Info); //! //! // This exporter will now run every 5 seconds, taking a snapshot, rendering it, and writing it //! // via `log!` at the informational level. This particular exporter is running directly on the //! // current thread, and not on a background thread. //! // //! // exporter.run(Duration::from_secs(5)); //! ``` //! Most exporters have the ability to run on the current thread or to be converted into a future //! which can be spawned on any Tokio-compatible runtime. //! //! # Facade //! //! `metrics` is `metrics-facade` compatible, and can be installed as the global metrics facade: //! ``` //! # extern crate metrics; //! #[macro_use] //! extern crate metrics_facade; //! use metrics::Receiver; //! //! Receiver::builder() //! .build() //! .expect("failed to create receiver") //! .install(); //! //! counter!("items_processed", 42); //! ``` //! //! [metrics_core]: https://docs.rs/metrics-core //! [`Recorder`]: https://docs.rs/metrics-core/0.3.1/metrics_core/trait.Recorder.html #![deny(missing_docs)] #![warn(unused_extern_crates)] mod builder; mod common; mod config; mod control; pub mod data; mod helper; mod receiver; mod registry; mod sink; #[cfg(any(feature = "metrics-exporter-log", feature = "metrics-exporter-http"))] pub mod exporters; #[cfg(any( feature = "metrics-recorder-text", feature = "metrics-recorder-prometheus" ))] pub mod recorders; pub use self::{ builder::{Builder, BuilderError}, common::{Delta, MetricName, MetricScope}, control::{Controller, SnapshotError}, receiver::Receiver, sink::{AsScoped, Sink, SinkError}, };