annotate rust/hg-core/src/logging.rs @ 52274:6aa4ee2bb128 stable tip

contrib: add a script to build all of the wheels on macOS

This is mostly a translation of `contrib/packaging/build-windows-wheels.bat`,
except the default pythons to build can be inferred from `setup.py` and/or
`pyproject.toml`, and all use the same configuration.  All we need to do is
force the building of translation files, tell it to skip pypy wheels, and tell
it to build universal2 wheels instead of for the current architecture.

use crate::errors::{HgError, HgResultExt, IoErrorContext, IoResultExt};
use crate::vfs::VfsImpl;
use std::io::Write;

/// An utility to append to a log file with the given name, and optionally
/// rotate it after it reaches a certain maximum size.
///
/// Rotation works by renaming "example.log" to "example.log.1", after renaming
/// "example.log.1" to "example.log.2" etc up to the given maximum number of
/// files.
pub struct LogFile<'a> {
    vfs: VfsImpl,
    name: &'a str,
    max_size: Option<u64>,
    max_files: u32,
}

impl<'a> LogFile<'a> {
    pub fn new(vfs: VfsImpl, name: &'a str) -> Self {
        Self {
            vfs,
            name,
            max_size: None,
            max_files: 0,
        }
    }

    /// Rotate before writing to a log file that was already larger than the
    /// given size, in bytes. `None` disables rotation.
    pub fn max_size(mut self, value: Option<u64>) -> Self {
        self.max_size = value;
        self
    }

    /// Keep this many rotated files `{name}.1` up to `{name}.{max}`, in
    /// addition to the original `{name}` file.
    pub fn max_files(mut self, value: u32) -> Self {
        self.max_files = value;
        self
    }

    /// Append the given `bytes` as-is to the log file, after rotating if
    /// needed.
    ///
    /// No trailing newline is added. Make sure to include one in `bytes` if
    /// desired.
    pub fn write(&self, bytes: &[u8]) -> Result<(), HgError> {
        let path = self.vfs.join(self.name);
        let context = || IoErrorContext::WritingFile(path.clone());
        let open = || {
            std::fs::OpenOptions::new()
                .create(true)
                .append(true)
                .open(&path)
                .with_context(context)
        };
        let mut file = open()?;
        if let Some(max_size) = self.max_size {
            if file.metadata().with_context(context)?.len() >= max_size {
                // For example with `max_files == 5`, the first iteration of
                // this loop has `i == 4` and renames `{name}.4` to `{name}.5`.
                // The last iteration renames `{name}.1` to
                // `{name}.2`
                for i in (1..self.max_files).rev() {
                    self.vfs
                        .rename(
                            format!("{}.{}", self.name, i),
                            format!("{}.{}", self.name, i + 1),
                        )
                        .io_not_found_as_none()?;
                }
                // Then rename `{name}` to `{name}.1`. This is the
                // previously-opened `file`.
                self.vfs
                    .rename(self.name, format!("{}.1", self.name))
                    .io_not_found_as_none()?;
                // Finally, create a new `{name}` file and replace our `file`
                // handle.
                file = open()?;
            }
        }
        file.write_all(bytes).with_context(context)?;
        file.sync_all().with_context(context)
    }
}

#[test]
fn test_rotation() {
    let temp = tempfile::tempdir().unwrap();
    let vfs = VfsImpl {
        base: temp.path().to_owned(),
    };
    let logger = LogFile::new(vfs.clone(), "log")
        .max_size(Some(3))
        .max_files(2);
    logger.write(b"one\n").unwrap();
    logger.write(b"two\n").unwrap();
    logger.write(b"3\n").unwrap();
    logger.write(b"four\n").unwrap();
    logger.write(b"five\n").unwrap();
    assert_eq!(vfs.read("log").unwrap(), b"five\n");
    assert_eq!(vfs.read("log.1").unwrap(), b"3\nfour\n");
    assert_eq!(vfs.read("log.2").unwrap(), b"two\n");
    assert!(vfs.read("log.3").io_not_found_as_none().unwrap().is_none());
}