272 lines
9.6 KiB
Rust
272 lines
9.6 KiB
Rust
//! The diff the review classifier reads, built from both sides of each
|
|
//! changed file rather than taken from the forge's `.diff`, whose context is
|
|
//! fixed at 3 lines. [`CONTEXT_LINES`] of context shows an enclosing gate (a
|
|
//! `config = lib.mkIf …`, an option's `default`) only when it is within that
|
|
//! many lines of the change; a gate further away is still out of view.
|
|
|
|
use std::fmt::{self, Write as _};
|
|
|
|
use std::time::Duration;
|
|
|
|
use similar::TextDiff;
|
|
|
|
/// Lines of context around each change. A block's enclosing
|
|
/// `config = lib.mkIf …` is in view when it opens within this many lines above
|
|
/// the block.
|
|
pub const CONTEXT_LINES: usize = 25;
|
|
|
|
/// The largest wide diff sent, in bytes, about 64k tokens of code. A larger
|
|
/// one gives way to the forge's `.diff`.
|
|
pub const MAX_BYTES: usize = 256 * 1024;
|
|
|
|
/// The most changed files a wide diff is read for. Each costs a few forge
|
|
/// reads per side, all within the one deadline the PR read runs under.
|
|
pub const MAX_FILES: usize = 100;
|
|
|
|
/// How long one file's diff may search for the smallest edit before settling
|
|
/// for a larger one. Without it a rewritten file of tens of thousands of
|
|
/// lines takes minutes.
|
|
const DIFF_TIMEOUT: Duration = Duration::from_secs(1);
|
|
|
|
/// One changed file: its path and bytes at the merge base and at the head,
|
|
/// `None` on a side where it does not exist.
|
|
#[derive(Clone, Debug, PartialEq, Eq)]
|
|
pub struct FileChange {
|
|
pub old_path: String,
|
|
pub new_path: String,
|
|
pub old: Option<Vec<u8>>,
|
|
pub new: Option<Vec<u8>>,
|
|
}
|
|
|
|
/// Why a PR of `count` changed files gets the forge's `.diff`, if it does.
|
|
pub fn too_many_files(count: usize) -> Option<String> {
|
|
(count > MAX_FILES).then(|| {
|
|
format!("the PR changes {count} files, more than the {MAX_FILES} a wide diff is read for")
|
|
})
|
|
}
|
|
|
|
/// `files` as one diff with [`CONTEXT_LINES`] of context, or why the forge's
|
|
/// `.diff` stands in: the result is over [`MAX_BYTES`].
|
|
pub fn wide(files: &[FileChange]) -> Result<String, String> {
|
|
render(files, CONTEXT_LINES, MAX_BYTES).map_err(|_| {
|
|
format!(
|
|
"the diff with {CONTEXT_LINES} lines of context is over the {MAX_BYTES} bytes a \
|
|
review sends"
|
|
)
|
|
})
|
|
}
|
|
|
|
/// `files` as one unified diff with `context` lines around each change, each
|
|
/// file in `git diff`'s shape: a `diff --git` line, `---`/`+++`, then hunks.
|
|
/// A file with a non-UTF-8 or NUL-bearing side is one `Binary files` line.
|
|
///
|
|
/// # Errors
|
|
/// The bytes rendered when the output passed `cap`; rendering stops there.
|
|
pub fn render(files: &[FileChange], context: usize, cap: usize) -> Result<String, usize> {
|
|
let mut out = Capped {
|
|
out: String::new(),
|
|
cap,
|
|
};
|
|
for file in files {
|
|
if section(&mut out, file, context).is_err() {
|
|
return Err(out.out.len());
|
|
}
|
|
}
|
|
Ok(out.out)
|
|
}
|
|
|
|
/// A `String` whose writes fail once it holds more than `cap` bytes, which
|
|
/// stops a `Display` impl writing into it.
|
|
struct Capped {
|
|
out: String,
|
|
cap: usize,
|
|
}
|
|
|
|
impl fmt::Write for Capped {
|
|
fn write_str(&mut self, s: &str) -> fmt::Result {
|
|
self.out.push_str(s);
|
|
if self.out.len() > self.cap {
|
|
Err(fmt::Error)
|
|
} else {
|
|
Ok(())
|
|
}
|
|
}
|
|
}
|
|
|
|
fn section(out: &mut Capped, file: &FileChange, context: usize) -> fmt::Result {
|
|
let (old_path, new_path) = (&file.old_path, &file.new_path);
|
|
writeln!(out, "diff --git a/{old_path} b/{new_path}")?;
|
|
if file.old.is_some() && file.new.is_some() && old_path != new_path {
|
|
writeln!(out, "rename from {old_path}\nrename to {new_path}")?;
|
|
}
|
|
let a = file
|
|
.old
|
|
.as_ref()
|
|
.map_or_else(|| "/dev/null".to_owned(), |_| format!("a/{old_path}"));
|
|
let b = file
|
|
.new
|
|
.as_ref()
|
|
.map_or_else(|| "/dev/null".to_owned(), |_| format!("b/{new_path}"));
|
|
let (Some(old), Some(new)) = (text(file.old.as_deref()), text(file.new.as_deref())) else {
|
|
return writeln!(out, "Binary files {a} and {b} differ");
|
|
};
|
|
let diff = TextDiff::configure()
|
|
.timeout(DIFF_TIMEOUT)
|
|
.diff_lines(old, new);
|
|
write!(
|
|
out,
|
|
"{}",
|
|
diff.unified_diff().context_radius(context).header(&a, &b)
|
|
)
|
|
}
|
|
|
|
/// A side's text: empty when the file is absent, `None` when it is binary.
|
|
fn text(bytes: Option<&[u8]>) -> Option<&str> {
|
|
let bytes = bytes.unwrap_or_default();
|
|
if bytes.contains(&0) {
|
|
return None;
|
|
}
|
|
std::str::from_utf8(bytes).ok()
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
fn change(path: &str, old: Option<&str>, new: Option<&str>) -> FileChange {
|
|
FileChange {
|
|
old_path: path.to_owned(),
|
|
new_path: path.to_owned(),
|
|
old: old.map(|s| s.as_bytes().to_vec()),
|
|
new: new.map(|s| s.as_bytes().to_vec()),
|
|
}
|
|
}
|
|
|
|
/// A Nix module whose `config = lib.mkIf …` block opens `gap` lines above
|
|
/// a firewall rule on the wireguard interface.
|
|
fn module(gap: usize, with_rule: bool) -> String {
|
|
let mut s =
|
|
String::from("{ lib, config, ... }:\n{\n config = lib.mkIf deployCfg.nats.enable {\n");
|
|
for i in 0..gap {
|
|
let _ = writeln!(s, " services.nats.settings.k{i} = {i};");
|
|
}
|
|
if with_rule {
|
|
s.push_str(
|
|
" networking.firewall.interfaces.wg0 = {\n allowedTCPPorts = lib.mkIf \
|
|
deployCfg.wireguard.enable [ 4222 ];\n };\n",
|
|
);
|
|
}
|
|
for i in 0..5 {
|
|
let _ = writeln!(s, " systemd.services.nats.environment.E{i} = \"{i}\";");
|
|
}
|
|
s.push_str(" };\n}\n");
|
|
s
|
|
}
|
|
|
|
/// The rule moves out of the module into a glue module that restates
|
|
/// both conditions.
|
|
fn move_into_glue() -> Vec<FileChange> {
|
|
let glue = "{ lib, config, ... }:\n{\n config = lib.mkIf (deployCfg.nats.enable && \
|
|
deployCfg.wireguard.enable) {\n networking.firewall.interfaces.wg0.\
|
|
allowedTCPPorts = [ 4222 ];\n };\n}\n";
|
|
vec![
|
|
change("nix/host-modules/glue-nats-wireguard.nix", None, Some(glue)),
|
|
change(
|
|
"nix/host-modules/swarm-nats.nix",
|
|
Some(&module(20, true)),
|
|
Some(&module(20, false)),
|
|
),
|
|
]
|
|
}
|
|
|
|
/// `count` lines, line `i` reading `line(i)`.
|
|
fn numbered(count: usize, line: impl Fn(usize) -> String) -> String {
|
|
(0..count).fold(String::new(), |mut s, i| {
|
|
let _ = writeln!(s, "{}", line(i));
|
|
s
|
|
})
|
|
}
|
|
|
|
const GATE: &str = "config = lib.mkIf deployCfg.nats.enable {";
|
|
|
|
#[test]
|
|
fn a_moved_block_keeps_its_enclosing_gate_in_view() {
|
|
let diff = wide(&move_into_glue()).expect("fits");
|
|
assert!(diff.contains(&format!("\n {GATE}\n")), "{diff}");
|
|
assert!(diff.contains("\n- allowedTCPPorts = lib.mkIf deployCfg.wireguard.enable"));
|
|
}
|
|
|
|
#[test]
|
|
fn three_lines_of_context_leave_that_gate_out() {
|
|
let diff = render(&move_into_glue(), 3, usize::MAX).unwrap();
|
|
assert!(!diff.contains(GATE), "{diff}");
|
|
}
|
|
|
|
#[test]
|
|
fn context_is_as_wide_as_asked_and_no_wider() {
|
|
let old = numbered(30, |i| format!("line {i}"));
|
|
let new = old.replace("line 15\n", "line fifteen\n");
|
|
let at = |n| render(&[change("f", Some(&old), Some(&new))], n, usize::MAX).unwrap();
|
|
let diff = at(10);
|
|
assert!(diff.contains("@@ -6,21 +6,21 @@"), "{diff}");
|
|
assert!(diff.contains(" line 5\n") && !diff.contains("line 4\n"));
|
|
assert!(at(CONTEXT_LINES).contains("@@ -1,30 +1,30 @@"));
|
|
}
|
|
|
|
#[test]
|
|
fn file_headers_follow_git_diff() {
|
|
let diff = render(
|
|
&[
|
|
change("added", None, Some("a\n")),
|
|
change("gone", Some("a\n"), None),
|
|
FileChange {
|
|
old_path: "old".to_owned(),
|
|
new_path: "new".to_owned(),
|
|
old: Some(b"a\n".to_vec()),
|
|
new: Some(b"b\n".to_vec()),
|
|
},
|
|
change("img", Some("a\n"), Some("\0")),
|
|
],
|
|
3,
|
|
usize::MAX,
|
|
)
|
|
.unwrap();
|
|
assert_eq!(
|
|
diff,
|
|
"diff --git a/added b/added\n--- /dev/null\n+++ b/added\n@@ -0,0 +1 @@\n+a\n\
|
|
diff --git a/gone b/gone\n--- a/gone\n+++ /dev/null\n@@ -1 +0,0 @@\n-a\n\
|
|
diff --git a/old b/new\nrename from old\nrename to new\n--- a/old\n+++ b/new\n\
|
|
@@ -1 +1 @@\n-a\n+b\n\
|
|
diff --git a/img b/img\nBinary files a/img and b/img differ\n"
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn a_wide_diff_over_the_limit_gives_way() {
|
|
let big = numbered(MAX_BYTES / 8, |i| format!("{i:07}"));
|
|
let edited = numbered(MAX_BYTES / 8, |i| format!("{i:07}x"));
|
|
let files = [change("big", Some(&big), Some(&edited))];
|
|
let reason = wide(&files).expect_err("over the limit");
|
|
assert!(reason.contains("over the"), "{reason}");
|
|
let small = [change("small", Some("a\n"), Some("b\n"))];
|
|
assert!(wide(&small).is_ok());
|
|
}
|
|
|
|
#[test]
|
|
fn rendering_stops_once_past_the_limit() {
|
|
let huge = numbered(MAX_BYTES / 2, |i| format!("{i:07}"));
|
|
let files = [change("huge", None, Some(&huge))];
|
|
let written = render(&files, CONTEXT_LINES, MAX_BYTES).expect_err("over the limit");
|
|
assert!(
|
|
written <= MAX_BYTES + "0000000\n".len(),
|
|
"{written} bytes rendered of a {}-byte file",
|
|
huge.len()
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn more_files_than_the_limit_give_way() {
|
|
assert!(too_many_files(MAX_FILES).is_none());
|
|
assert!(too_many_files(MAX_FILES + 1).is_some());
|
|
}
|
|
}
|