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//! What:
//! Runs a forwarded index writer again when real Git lost the race for the index to the commit service, instead of showing the
//! person Git's refusal.
//! Why:
//! The wait for the service's hold ends when the hold is released, but the service may take the index again for the next
//! landing before the writer's own Git has started (a burst of commits lands one batch after another), and Git then ends with
//! its refusal to create the index lock. For the few commands that take that lock before they change anything and read no
//! standard input, running them again once the service lets go is the same command the person typed. The refusal is kept in
//! a file while this can happen and is shown only when it is final, so a transient loss is never printed. Every other
//! command, and a lock that a foreign program holds, keep the behavior of native Git.
//!
//! In TS you'd write (pseudocode):
//! ```ts
//! for (let attempt = 0; attempt < ATTEMPTS; attempt++) { const run = await runCapturingStderr(git); if (!lostToService(run)) return show(run); await waitForServiceHold(); }
//! ```
use super::forwarding::{exit_code, git_command, outcome_of, run_real_git};
use super::scratch_location::scratch_file;
use super::service_index_wait::{foreign_holds, wait_for_service_hold_here};
use super::start_retry::RetryStart;
use super::worktree_copy_forward::ForwardedRun;
use std::ffi::OsString;
use std::io::{Read, Seek, SeekFrom, Write};
use std::path::Path;
use std::process::Stdio;
/// How many times the command is started at most while the service keeps taking the index first.
pub const ATTEMPTS: usize = 50;
/// What Git's refusal to create the index lock always names.
const LOCK_REFUSAL: &str = "index.lock";
/// The status Git dies with, which is also the status of its refusal to create a lock.
const DIE_STATUS: i32 = 128;
/// Options of `git add` that change nothing about its input and read no standard input.
const ADD_OPTIONS: [&str; 20] = [
"-v", "-n", "-f", "-A", "-u", "-N", "-q", "--verbose", "--dry-run", "--force", "--all", "--update", "--intent-to-add",
"--ignore-errors", "--refresh", "--renormalize", "--no-all", "--ignore-removal", "--sparse", "--no-warn-embedded-repo",
];
/// Options of `git rm` that read no standard input.
const REMOVE_OPTIONS: [&str; 10] = ["-f", "-n", "-q", "-r", "--cached", "--force", "--dry-run", "--quiet", "--ignore-unmatch", "--sparse"];
/// Options of `git mv` that read no standard input.
const MOVE_OPTIONS: [&str; 8] = ["-f", "-k", "-n", "-v", "--force", "--dry-run", "--verbose", "--sparse"];
/// What:
/// Whether the command is one that may be run again after it lost the index: it takes the index lock before it changes
/// anything, reads no standard input, asks the person nothing, and every option it has is one this list knows.
/// Why:
/// An unknown option, an interactive form or a pathspec file could make a second run differ from the first.
///
/// In TS you'd write (pseudocode):
/// ```ts
/// mayRunAgain('add', ['-A', '--', 'a.txt'])
/// ```
pub fn may_run_again(word: &[u8], after_word: &[OsString]) -> bool {
let known: &[&str] = match word {
b"add" => &ADD_OPTIONS,
b"rm" => &REMOVE_OPTIONS,
b"mv" => &MOVE_OPTIONS,
_ => return false,
};
for argument in after_word {
let Some(text) = argument.to_str() else { return false };
if text == "--" {
break;
}
if text.starts_with('-') && text != "-" && !known.contains(&text) {
return false;
}
}
return true;
}
/// Starts Git once with its standard error in `captured`, and returns its exit status.
fn run_once(real_git: &Path, arguments: &[OsString], overlay: &[(OsString, OsString)], captured: std::fs::File) -> std::io::Result<i32> {
let mut command = git_command(real_git, arguments, overlay);
command.stderr(Stdio::from(captured));
let status = command.status_retrying()?;
return Ok(exit_code(outcome_of(status)));
}
/// The command with every stream inherited, as a forwarded command runs when nothing needs to be kept.
fn run_plainly(real_git: &Path, arguments: &[OsString], overlay: &[(OsString, OsString)]) -> ForwardedRun {
return match run_real_git(real_git, arguments, overlay) {
Ok(outcome) => ForwardedRun::Ran(exit_code(outcome)),
Err(error) => ForwardedRun::Failed { stderr: format!("cli-git: cannot start {}: {error}\n", real_git.display()), code: super::action::ENGINE_FAILURE_EXIT_CODE },
};
}
/// What:
/// Runs the command, again while it ends with Git's refusal to create the index lock and the commit service has the index
/// (or has just let it go), and shows the last attempt's standard error.
/// Why:
/// The final attempt's words are Git's own; an attempt that is run again shows nothing.
///
/// In TS you'd write (pseudocode):
/// ```ts
/// await runAgainWhileServiceHoldsIndex({ realGit, arguments, overlay, environment, realIndex, name })
/// ```
pub fn run_again_while_service_holds(
real_git: &Path,
arguments: &[OsString],
overlay: &[(OsString, OsString)],
environment: &[(OsString, OsString)],
real_index: &Path,
name: &str,
shown: &mut dyn Write,
) -> ForwardedRun {
for attempt in 1..=ATTEMPTS {
// Without a place to keep the output the command runs as it always did, and its refusal, if any, is Git's own.
let Ok(mut file) = scratch_file(environment) else { return run_plainly(real_git, arguments, overlay) };
let Ok(for_child) = file.try_clone() else { return run_plainly(real_git, arguments, overlay) };
let code: i32 = match run_once(real_git, arguments, overlay, for_child) {
Ok(code) => code,
Err(error) => {
return ForwardedRun::Failed { stderr: format!("cli-git: cannot start {}: {error}\n", real_git.display()), code: super::action::ENGINE_FAILURE_EXIT_CODE };
}
};
let mut said: Vec<u8> = Vec::new();
let read_back = file.seek(SeekFrom::Start(0)).and_then(|_| { return file.read_to_end(&mut said); });
let lost_to_service: bool = code == DIE_STATUS
&& read_back.is_ok()
&& String::from_utf8_lossy(said.as_slice()).contains(LOCK_REFUSAL)
&& !foreign_holds(real_index);
if lost_to_service && attempt < ATTEMPTS {
wait_for_service_hold_here(real_index, name);
continue;
}
// A closed terminal is not a reason to stop the command the person asked for.
let _shown = shown.write_all(said.as_slice()).and_then(|()| { return shown.flush(); });
return ForwardedRun::Ran(code);
}
return ForwardedRun::Ran(DIE_STATUS);
}
/// The retry is controlled in the test module.
#[cfg(test)]
#[path = "service_hold_retry_tests.rs"]
mod tests;