Refactor bounds definition.

Author: ehuss

Diff for: Cargo.lock

@@ -33,6 +33,7 @@ xz2 = "0.1.7"
 chrono = "0.4.22"
 colored = "2"
 regex = "1.10.1"
+toml = "0.8.10"
 
 [dev-dependencies]
 quickcheck = "1"

Diff for: Cargo.toml

@@ -0,0 +1,224 @@
+//! Definitions of bisection bounds.
+
+use crate::toolchains::{
+    download_progress, parse_to_naive_date, Toolchain, NIGHTLY_SERVER, YYYY_MM_DD,
+};
+use crate::GitDate;
+use crate::Opts;
+use crate::{today, EPOCH_COMMIT};
+use anyhow::bail;
+use chrono::NaiveDate;
+use reqwest::blocking::Client;
+use std::io::Read;
+use std::str::FromStr;
+
+/// A bisection boundary.
+#[derive(Clone, Debug)]
+pub enum Bound {
+    Commit(String),
+    Date(GitDate),
+}
+
+impl FromStr for Bound {
+    type Err = std::convert::Infallible;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        parse_to_naive_date(s)
+            .map(Self::Date)
+            .or_else(|_| Ok(Self::Commit(s.to_string())))
+    }
+}
+
+impl Bound {
+    /// Returns the SHA of this boundary.
+    ///
+    /// For nightlies, this will fetch from the network.
+    pub fn sha(&self) -> anyhow::Result<String> {
+        match self {
+            Bound::Commit(commit) => Ok(commit.clone()),
+            Bound::Date(date) => {
+                let date_str = date.format(YYYY_MM_DD);
+                let url =
+                    format!("{NIGHTLY_SERVER}/{date_str}/channel-rust-nightly-git-commit-hash.txt");
+
+                eprintln!("fetching {url}");
+                let client = Client::new();
+                let name = format!("nightly manifest {date_str}");
+                let mut response = download_progress(&client, &name, &url)?;
+                let mut commit = String::new();
+                response.read_to_string(&mut commit)?;
+
+                eprintln!("converted {date_str} to {commit}");
+
+                Ok(commit)
+            }
+        }
+    }
+}
+
+/// The starting bisection bounds.
+pub enum Bounds {
+    /// Indicates to search backwards from the given date to find the start
+    /// date where the regression does not occur.
+    SearchNightlyBackwards { end: GitDate },
+    /// Search between two commits.
+    Commits { start: String, end: String },
+    /// Search between two dates.
+    Dates { start: GitDate, end: GitDate },
+}
+
+impl Bounds {
+    pub fn from_args(args: &Opts) -> anyhow::Result<Bounds> {
+        let (start, end) = translate_tags(&args)?;
+        let today = today();
+        let check_in_future = |which, date: &NaiveDate| -> anyhow::Result<()> {
+            if date > &today {
+                bail!(
+                    "{which} date should be on or before current date, \
+                     got {which} date request: {date} and current date is {today}"
+                );
+            }
+            Ok(())
+        };
+        let bounds = match (start, end) {
+            // Neither --start or --end specified.
+            (None, None) => Bounds::SearchNightlyBackwards {
+                end: installed_nightly_or_latest()?,
+            },
+
+            // --start or --end is a commit
+            (Some(Bound::Commit(start)), Some(Bound::Commit(end))) => {
+                Bounds::Commits { start, end }
+            }
+            (Some(Bound::Commit(start)), None) => Bounds::Commits {
+                start,
+                end: "origin/master".to_string(),
+            },
+            (None, Some(Bound::Commit(end))) => Bounds::Commits {
+                start: EPOCH_COMMIT.to_string(),
+                end,
+            },
+
+            // --start or --end is a date
+            (Some(Bound::Date(start)), Some(Bound::Date(end))) => {
+                check_in_future("start", &start)?;
+                check_in_future("end", &end)?;
+                Bounds::Dates { start, end }
+            }
+            (Some(Bound::Date(start)), None) => {
+                check_in_future("start", &start)?;
+                Bounds::Dates {
+                    start,
+                    end: find_latest_nightly()?,
+                }
+            }
+            (None, Some(Bound::Date(end))) => {
+                check_in_future("end", &end)?;
+                if args.by_commit {
+                    bail!("--by-commit with an end date requires --start to be specified");
+                }
+                Bounds::SearchNightlyBackwards { end }
+            }
+
+            // Mixed not supported.
+            (Some(Bound::Commit(_)), Some(Bound::Date(_)))
+            | (Some(Bound::Date(_)), Some(Bound::Commit(_))) => bail!(
+                "cannot take different types of bounds for start/end, \
+                 got start: {:?} and end {:?}",
+                args.start,
+                args.end
+            ),
+        };
+        if let Bounds::Dates { start, end } = &bounds {
+            if end < start {
+                bail!("end should be after start, got start: {start} and end {end}");
+            }
+            if args.by_commit {
+                eprintln!("finding commit range that corresponds to dates specified");
+                let bounds = Bounds::Commits {
+                    start: date_to_sha(&start)?,
+                    end: date_to_sha(&end)?,
+                };
+                return Ok(bounds);
+            }
+        }
+        Ok(bounds)
+    }
+}
+
+/// Translates a tag-like bound (such as `1.62.0`) to a `Bound::Date` so that
+/// bisecting works for versions older than 167 days.
+fn translate_tags(args: &Opts) -> anyhow::Result<(Option<Bound>, Option<Bound>)> {
+    let is_tag = |bound: &Option<Bound>| -> bool {
+        match bound {
+            Some(Bound::Commit(commit)) => commit.contains('.'),
+            None | Some(Bound::Date(_)) => false,
+        }
+    };
+    let is_datelike = |bound: &Option<Bound>| -> bool {
+        matches!(bound, None | Some(Bound::Date(_))) || is_tag(bound)
+    };
+    if !(is_datelike(&args.start) && is_datelike(&args.end)) {
+        // If the user specified an actual commit for one bound, then don't
+        // even try to convert the other bound to a date.
+        return Ok((args.start.clone(), args.end.clone()));
+    }
+    let fixup = |which: &str, bound: &Option<Bound>| -> anyhow::Result<Option<Bound>> {
+        if is_tag(bound) {
+            if let Some(Bound::Commit(tag)) = bound {
+                let date = args
+                    .access
+                    .repo()
+                    .bound_to_date(Bound::Commit(tag.clone()))?;
+                eprintln!(
+                    "translating --{which}={tag} to {date}",
+                    date = date.format(YYYY_MM_DD)
+                );
+                return Ok(Some(Bound::Date(date)));
+            }
+        }
+        Ok(bound.clone())
+    };
+    Ok((fixup("start", &args.start)?, fixup("end", &args.end)?))
+}
+
+/// Returns the commit SHA of the nightly associated with the given date.
+fn date_to_sha(date: &NaiveDate) -> anyhow::Result<String> {
+    let date_str = date.format(YYYY_MM_DD);
+    let url = format!("{NIGHTLY_SERVER}/{date_str}/channel-rust-nightly-git-commit-hash.txt");
+
+    eprintln!("fetching {url}");
+    let client = Client::new();
+    let name = format!("nightly manifest {date_str}");
+    let mut response = download_progress(&client, &name, &url)?;
+    let mut commit = String::new();
+    response.read_to_string(&mut commit)?;
+
+    eprintln!("converted {date_str} to {commit}");
+
+    Ok(commit)
+}
+
+/// Returns the date of the nightly toolchain currently installed. If no
+/// nightly is found, then it goes to the network to determine the date of the
+/// latest nightly.
+fn installed_nightly_or_latest() -> anyhow::Result<GitDate> {
+    if let Some(date) = Toolchain::default_nightly() {
+        return Ok(date);
+    }
+    find_latest_nightly()
+}
+
+/// Returns the date of the latest nightly (fetched from the network).
+fn find_latest_nightly() -> anyhow::Result<GitDate> {
+    let url = format!("{NIGHTLY_SERVER}/channel-rust-nightly.toml");
+    eprintln!("fetching {url}");
+    let client = Client::new();
+    let mut response = download_progress(&client, "nightly manifest", &url)?;
+    let mut manifest = String::new();
+    response.read_to_string(&mut manifest)?;
+    let manifest: toml::Value = toml::from_str(&manifest)?;
+    let date = manifest["date"].as_str().expect("date is a string");
+    let date = NaiveDate::parse_from_str(date, "%Y-%m-%d")?;
+    eprintln!("determined the latest nightly is {date}");
+    Ok(date)
+}