src/desc: Validate metric and label names via regex crate (#354)

Signed-off-by: Max Inden <[email protected]>

Author: mxinden

benches/desc.rs

@@ -0,0 +1,32 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#![feature(test)]
+
+extern crate test;
+
+use prometheus::core::Desc;
+
+use test::{black_box, Bencher};
+
+#[bench]
+fn description_validation(b: &mut Bencher) {
+    b.iter(|| {
+        black_box(Desc::new(
+            "api_http_requests_total".to_string(),
+            "not empty help".to_string(),
+            vec!["method".to_string(), "handler".to_string()],
+            Default::default(),
+        ))
+    });
+}

src/desc.rs

@@ -5,53 +5,30 @@ use std::collections::{BTreeSet, HashMap};
 use std::hash::Hasher;
 
 use fnv::FnvHasher;
+use regex::Regex;
 
 use crate::errors::{Error, Result};
 use crate::metrics::SEPARATOR_BYTE;
 use crate::proto::LabelPair;
 
 // Details of required format are at
-//   https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
+// https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
 fn is_valid_metric_name(name: &str) -> bool {
-    // Valid metric names must match regex [a-zA-Z_:][a-zA-Z0-9_:]*.
-    fn valid_start(c: char) -> bool {
-        c.is_ascii()
-            && match c as u8 {
-                b'a'..=b'z' | b'A'..=b'Z' | b'_' | b':' => true,
-                _ => false,
-            }
-    }
-
-    fn valid_char(c: char) -> bool {
-        c.is_ascii()
-            && match c as u8 {
-                b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' | b'_' | b':' => true,
-                _ => false,
-            }
+    lazy_static! {
+        static ref VALIDATOR: Regex =
+            Regex::new("^[a-zA-Z_:][a-zA-Z0-9_:]*$").expect("Regex to be valid.");
     }
 
-    name.starts_with(valid_start) && !name.contains(|c| !valid_char(c))
+    VALIDATOR.is_match(name)
 }
 
 fn is_valid_label_name(name: &str) -> bool {
-    // Valid label names must match regex [a-zA-Z_][a-zA-Z0-9_]*.
-    fn valid_start(c: char) -> bool {
-        c.is_ascii()
-            && match c as u8 {
-                b'a'..=b'z' | b'A'..=b'Z' | b'_' => true,
-                _ => false,
-            }
-    }
-
-    fn valid_char(c: char) -> bool {
-        c.is_ascii()
-            && match c as u8 {
-                b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' | b'_' => true,
-                _ => false,
-            }
+    lazy_static! {
+        static ref VALIDATOR: Regex =
+            Regex::new("^[a-zA-Z_][a-zA-Z0-9_]*$").expect("Regex to be valid.");
     }
 
-    name.starts_with(valid_start) && !name.contains(|c| !valid_char(c))
+    VALIDATOR.is_match(name)
 }
 
 /// The descriptor used by every Prometheus [`Metric`](crate::core::Metric). It is essentially