From 29330b0dc14d9d4634077d1badf2b16d532e1185 Mon Sep 17 00:00:00 2001
From: Oliver Gould <ver@buoyant.io>
Date: Mon, 30 Apr 2018 10:52:08 -0700
Subject: [PATCH] Move `metrics::Serve` into its own module (#877)

With this change, metrics/mod.rs now contains only metrics types.
---
 proxy/src/telemetry/metrics/mod.rs   | 81 +---------------------------
 proxy/src/telemetry/metrics/serve.rs | 78 +++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 79 deletions(-)
 create mode 100644 proxy/src/telemetry/metrics/serve.rs

diff --git a/proxy/src/telemetry/metrics/mod.rs b/proxy/src/telemetry/metrics/mod.rs
index 712035b56..996cc119e 100644
--- a/proxy/src/telemetry/metrics/mod.rs
+++ b/proxy/src/telemetry/metrics/mod.rs
@@ -30,18 +30,7 @@ use std::default::Default;
 use std::{fmt, time};
 use std::hash::Hash;
 use std::sync::{Arc, Mutex};
-use std::io::Write;
 
-use deflate::CompressionOptions;
-use deflate::write::GzEncoder;
-use futures::future::{self, FutureResult};
-use hyper::{self, Body, StatusCode};
-use hyper::header::{AcceptEncoding, ContentEncoding, ContentType, Encoding, QualityItem};
-use hyper::server::{
-    Response as HyperResponse,
-    Request as HyperRequest,
-    Service as HyperService,
-};
 use indexmap::IndexMap;
 
 use ctx;
@@ -52,6 +41,7 @@ mod histogram;
 mod labels;
 mod latency;
 mod record;
+mod serve;
 
 use self::counter::Counter;
 use self::gauge::Gauge;
@@ -64,6 +54,7 @@ use self::labels::{
 };
 pub use self::labels::DstLabels;
 pub use self::record::Record;
+pub use self::serve::Serve;
 
 #[derive(Debug, Clone)]
 struct Metrics {
@@ -96,12 +87,6 @@ struct Metric<M, L: Hash + Eq> {
     values: IndexMap<L, M>
 }
 
-/// Serve Prometheues metrics.
-#[derive(Debug, Clone)]
-pub struct Serve {
-    metrics: Arc<Mutex<Metrics>>,
-}
-
 /// Construct the Prometheus metrics.
 ///
 /// Returns the `Record` and `Serve` sides. The `Serve` side
@@ -393,65 +378,3 @@ impl<L, V> fmt::Display for Metric<Histogram<V>, L> where
         Ok(())
     }
 }
-
-// ===== impl Serve =====
-
-impl Serve {
-    fn new(metrics: &Arc<Mutex<Metrics>>) -> Self {
-        Serve {
-            metrics: metrics.clone(),
-        }
-    }
-}
-
-fn is_gzip(req: &HyperRequest) -> bool {
-    if let Some(accept_encodings) = req
-        .headers()
-        .get::<AcceptEncoding>()
-    {
-        return accept_encodings
-            .iter()
-            .any(|&QualityItem { ref item, .. }| item == &Encoding::Gzip)
-    }
-    false
-}
-
-impl HyperService for Serve {
-    type Request = HyperRequest;
-    type Response = HyperResponse;
-    type Error = hyper::Error;
-    type Future = FutureResult<Self::Response, Self::Error>;
-
-    fn call(&self, req: Self::Request) -> Self::Future {
-        if req.path() != "/metrics" {
-            return future::ok(HyperResponse::new()
-                .with_status(StatusCode::NotFound));
-        }
-
-        let metrics = self.metrics.lock()
-            .expect("metrics lock poisoned");
-
-        let resp = if is_gzip(&req) {
-            trace!("gzipping metrics");
-            let mut writer = GzEncoder::new(Vec::<u8>::new(), CompressionOptions::fast());
-            write!(&mut writer, "{}", *metrics)
-                .and_then(|_| writer.finish())
-                .map(|body| {
-                    HyperResponse::new()
-                        .with_header(ContentEncoding(vec![Encoding::Gzip]))
-                        .with_header(ContentType::plaintext())
-                        .with_body(Body::from(body))
-                })
-        } else {
-            let mut writer = Vec::<u8>::new();
-            write!(&mut writer, "{}", *metrics)
-                .map(|_| {
-                    HyperResponse::new()
-                        .with_header(ContentType::plaintext())
-                        .with_body(Body::from(writer))
-                })
-        };
-
-        future::result(resp.map_err(hyper::Error::Io))
-    }
-}
diff --git a/proxy/src/telemetry/metrics/serve.rs b/proxy/src/telemetry/metrics/serve.rs
new file mode 100644
index 000000000..bae2d97c2
--- /dev/null
+++ b/proxy/src/telemetry/metrics/serve.rs
@@ -0,0 +1,78 @@
+use deflate::CompressionOptions;
+use deflate::write::GzEncoder;
+use futures::future::{self, FutureResult};
+use hyper::{self, Body, StatusCode};
+use hyper::header::{AcceptEncoding, ContentEncoding, ContentType, Encoding, QualityItem};
+use hyper::server::{Request, Response, Service};
+use std::io::Write;
+use std::sync::{Arc, Mutex};
+
+use super::Metrics;
+
+/// Serve Prometheues metrics.
+#[derive(Debug, Clone)]
+pub struct Serve {
+    metrics: Arc<Mutex<Metrics>>,
+}
+
+// ===== impl Serve =====
+
+impl Serve {
+    pub(super) fn new(metrics: &Arc<Mutex<Metrics>>) -> Self {
+        Serve {
+            metrics: metrics.clone(),
+        }
+    }
+
+    fn is_gzip(req: &Request) -> bool {
+        if let Some(accept_encodings) = req
+            .headers()
+            .get::<AcceptEncoding>()
+        {
+            return accept_encodings
+                .iter()
+                .any(|&QualityItem { ref item, .. }| item == &Encoding::Gzip)
+        }
+        false
+    }
+}
+
+impl Service for Serve {
+    type Request = Request;
+    type Response = Response;
+    type Error = hyper::Error;
+    type Future = FutureResult<Self::Response, Self::Error>;
+
+    fn call(&self, req: Self::Request) -> Self::Future {
+        if req.path() != "/metrics" {
+            return future::ok(Response::new()
+                .with_status(StatusCode::NotFound));
+        }
+
+        let metrics = self.metrics.lock()
+            .expect("metrics lock poisoned");
+
+        let resp = if Self::is_gzip(&req) {
+            trace!("gzipping metrics");
+            let mut writer = GzEncoder::new(Vec::<u8>::new(), CompressionOptions::fast());
+            write!(&mut writer, "{}", *metrics)
+                .and_then(|_| writer.finish())
+                .map(|body| {
+                    Response::new()
+                        .with_header(ContentEncoding(vec![Encoding::Gzip]))
+                        .with_header(ContentType::plaintext())
+                        .with_body(Body::from(body))
+                })
+        } else {
+            let mut writer = Vec::<u8>::new();
+            write!(&mut writer, "{}", *metrics)
+                .map(|_| {
+                    Response::new()
+                        .with_header(ContentType::plaintext())
+                        .with_body(Body::from(writer))
+                })
+        };
+
+        future::result(resp.map_err(hyper::Error::Io))
+    }
+}