Add ServerTiming parsing

Author: yoshuawuyts

src/trace/server_timing/entry.rs

@@ -1,9 +1,6 @@
-use std::str::FromStr;
 use std::time::Duration;
 
 use crate::headers::HeaderValue;
-use crate::Status;
-use crate::{ensure, format_err};
 
 /// An individual `ServerTiming` entry.
 //
@@ -17,11 +14,11 @@ use crate::{ensure, format_err};
 // 4. metric + value + desc  cache;desc="Cache Read";dur=23.2
 //
 // Multiple different entries per line are supported; separated with a `,`.
-#[derive(Debug)]
+#[derive(Debug, Clone, Eq, PartialEq)]
 pub struct Entry {
-    name: String,
-    dur: Option<Duration>,
-    desc: Option<String>,
+    pub(crate) name: String,
+    pub(crate) dur: Option<Duration>,
+    pub(crate) desc: Option<String>,
 }
 
 impl Entry {
@@ -76,90 +73,11 @@ impl From<Entry> for HeaderValue {
     }
 }
 
-impl FromStr for Entry {
-    type Err = crate::Error;
-    // Create an entry from a string. Parsing rules in ABNF are:
-    //
-    // ```
-    // Server-Timing             = #server-timing-metric
-    // server-timing-metric      = metric-name *( OWS ";" OWS server-timing-param )
-    // metric-name               = token
-    // server-timing-param       = server-timing-param-name OWS "=" OWS server-timing-param-value
-    // server-timing-param-name  = token
-    // server-timing-param-value = token / quoted-string
-    // ```
-    //
-    // Source: https://w3c.github.io/server-timing/#the-server-timing-header-field
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let mut parts = s.trim().split(';');
-
-        // Get the name. This is non-optional.
-        let name = parts
-            .next()
-            .ok_or_else(|| format_err!("Server timing headers must include a name"))?
-            .trim_end();
-
-        // We must extract these values from the k-v pairs that follow.
-        let mut dur = None;
-        let mut desc = None;
-
-        for mut part in parts {
-            ensure!(
-                !part.is_empty(),
-                "Server timing params cannot end with a trailing `;`"
-            );
-
-            part = part.trim_start();
-
-            let mut params = part.split('=');
-            let name = params
-                .next()
-                .ok_or_else(|| format_err!("Server timing params must have a name"))?
-                .trim_end();
-            let mut value = params
-                .next()
-                .ok_or_else(|| format_err!("Server timing params must have a value"))?
-                .trim_start();
-
-            match name {
-                "dur" => {
-                    let millis: f64 = value.parse().status(400).map_err(|_| {
-                        format_err!("Server timing duration params must be a valid double-precision floating-point number.")
-                    })?;
-                    dur = Some(Duration::from_secs_f64(millis / 1000.0));
-                }
-                "desc" => {
-                    // Ensure quotes line up, and strip them from the resulting output
-                    if value.starts_with('"') {
-                        value = &value[1..value.len()];
-                        ensure!(
-                            value.ends_with('"'),
-                            "Server timing description params must use matching quotes"
-                        );
-                        value = &value[0..value.len() - 1];
-                    } else {
-                        ensure!(
-                            !value.ends_with('"'),
-                            "Server timing description params must use matching quotes"
-                        );
-                    }
-                    desc = Some(value.to_string());
-                }
-                _ => continue,
-            }
-        }
-
-        Ok(Entry {
-            name: name.to_string(),
-            dur,
-            desc,
-        })
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::*;
+    use crate::headers::HeaderValue;
+    use std::time::Duration;
 
     #[test]
     fn encode() -> crate::Result<()> {
@@ -180,71 +98,4 @@ mod test {
         assert_eq!(val, r#"Server; dur=1000; desc="A server timing""#);
         Ok(())
     }
-
-    #[test]
-    fn decode() -> crate::Result<()> {
-        // Metric name only.
-        assert_entry("Server", "Server", None, None)?;
-        assert_entry("Server ", "Server", None, None)?;
-        assert_entry_err(
-            "Server ;",
-            "Server timing params cannot end with a trailing `;`",
-        );
-        assert_entry_err(
-            "Server; ",
-            "Server timing params cannot end with a trailing `;`",
-        );
-
-        // Metric name + param
-        assert_entry("Server; dur=1000", "Server", Some(1000), None)?;
-        assert_entry("Server; dur =1000", "Server", Some(1000), None)?;
-        assert_entry("Server; dur= 1000", "Server", Some(1000), None)?;
-        assert_entry("Server; dur = 1000", "Server", Some(1000), None)?;
-        assert_entry_err(
-            "Server; dur=1000;",
-            "Server timing params cannot end with a trailing `;`",
-        );
-
-        // Metric name + desc
-        assert_entry(r#"DB; desc="a db""#, "DB", None, Some("a db"))?;
-        assert_entry(r#"DB; desc ="a db""#, "DB", None, Some("a db"))?;
-        assert_entry(r#"DB; desc= "a db""#, "DB", None, Some("a db"))?;
-        assert_entry(r#"DB; desc = "a db""#, "DB", None, Some("a db"))?;
-        assert_entry(r#"DB; desc=a_db"#, "DB", None, Some("a_db"))?;
-        assert_entry_err(
-            r#"DB; desc="db"#,
-            "Server timing description params must use matching quotes",
-        );
-        assert_entry_err(
-            "Server; desc=a_db;",
-            "Server timing params cannot end with a trailing `;`",
-        );
-
-        // Metric name + dur + desc
-        assert_entry(
-            r#"Server; dur=1000; desc="a server""#,
-            "Server",
-            Some(1000),
-            Some("a server"),
-        )?;
-        assert_entry_err(
-            r#"Server; dur=1000; desc="a server";"#,
-            "Server timing params cannot end with a trailing `;`",
-        );
-        Ok(())
-    }
-
-    fn assert_entry_err(s: &str, msg: &str) {
-        let err = Entry::from_str(s).unwrap_err();
-        assert_eq!(format!("{}", err), msg);
-    }
-
-    /// Assert an entry and all of its fields.
-    fn assert_entry(s: &str, n: &str, du: Option<u64>, de: Option<&str>) -> crate::Result<()> {
-        let e = Entry::from_str(s)?;
-        assert_eq!(e.name(), n);
-        assert_eq!(e.duration(), du.map(|du| Duration::from_millis(du)));
-        assert_eq!(e.description(), de);
-        Ok(())
-    }
 }

src/trace/server_timing/mod.rs

@@ -1,12 +1,18 @@
 //! Metrics and descriptions for the given request-response cycle.
 
 mod entry;
+mod parse;
 
 pub use entry::Entry;
+use parse::parse_header;
 
+use std::convert::AsMut;
 use std::iter::Iterator;
 use std::slice;
 
+use crate::headers::HeaderValue;
+use crate::Headers;
+
 /// Metrics and descriptions for the given request-response cycle.
 ///
 /// This is an implementation of the W3C [Server
@@ -19,6 +25,33 @@ pub struct ServerTiming {
 }
 
 impl ServerTiming {
+    /// Create a new instance of `ServerTiming`.
+    pub fn new() -> Self {
+        Self { timings: vec![] }
+    }
+    /// Create a new instance from headers.
+    pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Self> {
+        let mut timings = vec![];
+        let values = headers.as_ref().get("server-timing");
+        for value in values.iter().map(|h| h.iter()).flatten() {
+            parse_header(value.as_str(), &mut timings)?;
+        }
+        Ok(Self { timings })
+    }
+
+    /// Sets the `Server-Timing` header.
+    pub fn apply(&self, mut headers: impl AsMut<Headers>) {
+        for timing in &self.timings {
+            let value: HeaderValue = timing.clone().into();
+            headers.as_mut().insert("server-timing", value);
+        }
+    }
+
+    /// Push an entry into the list of entries.
+    pub fn push(&mut self, entry: Entry) {
+        self.timings.push(entry);
+    }
+
     /// An iterator visiting all server timings.
     pub fn into_iter(self) -> IntoIter {
         IntoIter {
@@ -128,7 +161,22 @@ impl<'a> Iterator for IterMut<'a> {
     }
 }
 
-// mod test {
-//     const CASE1: &str =
-//         "Server-Timing: metric1; dur=1.1; desc=document, metric1; dur=1.2; desc=document";
-// }
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::headers::Headers;
+
+    #[test]
+    fn smoke() -> crate::Result<()> {
+        let mut timings = ServerTiming::new();
+        timings.push(Entry::new("server".to_owned(), None, None)?);
+
+        let mut headers = Headers::new();
+        timings.apply(&mut headers);
+
+        let timings = ServerTiming::from_headers(headers)?;
+        let entry = timings.iter().next().unwrap();
+        assert_eq!(entry.name(), "server");
+        Ok(())
+    }
+}