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// Cadence - An extensible Statsd client for Rust! // // Copyright 2015-2017 TSH Labs // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. use std::io; /// Trait for various backends that send Statsd metrics somewhere. /// /// The metric string will be in the canonical format to be sent to a /// Statsd server. The metric string will not include a trailing newline. /// Examples of each supported metric type are given below. /// /// ## Counter /// /// ``` text /// some.counter:123|c /// ``` /// /// ## Timer /// /// ``` text /// some.timer:456|ms /// ``` /// /// ## Gauge /// /// ``` text /// some.gauge:5|g /// ``` /// /// ## Meter /// /// ``` text /// some.meter:8|m /// ``` /// /// ## Histogram /// /// ``` text /// some.histogram:4|h /// ``` /// /// See the [Statsd spec](https://github.com/b/statsd_spec) for more /// information. pub trait MetricSink { /// Send the Statsd metric using this sink and return the number of bytes /// written or an I/O error. fn emit(&self, metric: &str) -> io::Result<usize>; } /// Implementation of a `MetricSink` that discards all metrics. /// /// Useful for disabling metric collection or unit tests. #[derive(Debug, Clone)] pub struct NopMetricSink; impl MetricSink for NopMetricSink { #[allow(unused_variables)] fn emit(&self, metric: &str) -> io::Result<usize> { Ok(0) } } #[cfg(test)] mod tests { use super::{MetricSink, NopMetricSink}; #[test] fn test_nop_metric_sink() { let sink = NopMetricSink; assert_eq!(0, sink.emit("baz:4|c").unwrap()); } }