annotate rust/hg-core/src/dirstate/parsers.rs @ 44541:d880805d5442

hg-core: add function timing information

This change makes use of the newly added logging infrastructure to trace the
execution time of some important calls.

This approach is very much complementary to using a profiler and will not
guard against out-of-order execution or other kinds of compiler optimizations.
That said, it is useful to get a rough high-level idea of where time is spent.

Differential Revision: https://phab.mercurial-scm.org/D8253

// Copyright 2019 Raphaël Gomès <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use crate::utils::hg_path::HgPath;
use crate::{
    dirstate::{CopyMap, EntryState, StateMap},
    DirstateEntry, DirstatePackError, DirstateParents, DirstateParseError,
};
use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use micro_timer::timed;
use std::convert::{TryFrom, TryInto};
use std::io::Cursor;
use std::time::Duration;

/// Parents are stored in the dirstate as byte hashes.
pub const PARENT_SIZE: usize = 20;
/// Dirstate entries have a static part of 8 + 32 + 32 + 32 + 32 bits.
const MIN_ENTRY_SIZE: usize = 17;

// TODO parse/pack: is mutate-on-loop better for performance?

#[timed]
pub fn parse_dirstate(
    state_map: &mut StateMap,
    copy_map: &mut CopyMap,
    contents: &[u8],
) -> Result<DirstateParents, DirstateParseError> {
    if contents.len() < PARENT_SIZE * 2 {
        return Err(DirstateParseError::TooLittleData);
    }

    let mut curr_pos = PARENT_SIZE * 2;
    let parents = DirstateParents {
        p1: contents[..PARENT_SIZE].try_into().unwrap(),
        p2: contents[PARENT_SIZE..curr_pos].try_into().unwrap(),
    };

    while curr_pos < contents.len() {
        if curr_pos + MIN_ENTRY_SIZE > contents.len() {
            return Err(DirstateParseError::Overflow);
        }
        let entry_bytes = &contents[curr_pos..];

        let mut cursor = Cursor::new(entry_bytes);
        let state = EntryState::try_from(cursor.read_u8()?)?;
        let mode = cursor.read_i32::<BigEndian>()?;
        let size = cursor.read_i32::<BigEndian>()?;
        let mtime = cursor.read_i32::<BigEndian>()?;
        let path_len = cursor.read_i32::<BigEndian>()? as usize;

        if path_len > contents.len() - curr_pos {
            return Err(DirstateParseError::Overflow);
        }

        // Slice instead of allocating a Vec needed for `read_exact`
        let path = &entry_bytes[MIN_ENTRY_SIZE..MIN_ENTRY_SIZE + (path_len)];

        let (path, copy) = match memchr::memchr(0, path) {
            None => (path, None),
            Some(i) => (&path[..i], Some(&path[(i + 1)..])),
        };

        if let Some(copy_path) = copy {
            copy_map.insert(
                HgPath::new(path).to_owned(),
                HgPath::new(copy_path).to_owned(),
            );
        };
        state_map.insert(
            HgPath::new(path).to_owned(),
            DirstateEntry {
                state,
                mode,
                size,
                mtime,
            },
        );
        curr_pos = curr_pos + MIN_ENTRY_SIZE + (path_len);
    }

    Ok(parents)
}

/// `now` is the duration in seconds since the Unix epoch
pub fn pack_dirstate(
    state_map: &mut StateMap,
    copy_map: &CopyMap,
    parents: DirstateParents,
    now: Duration,
) -> Result<Vec<u8>, DirstatePackError> {
    // TODO move away from i32 before 2038.
    let now: i32 = now.as_secs().try_into().expect("time overflow");

    let expected_size: usize = state_map
        .iter()
        .map(|(filename, _)| {
            let mut length = MIN_ENTRY_SIZE + filename.len();
            if let Some(copy) = copy_map.get(filename) {
                length += copy.len() + 1;
            }
            length
        })
        .sum();
    let expected_size = expected_size + PARENT_SIZE * 2;

    let mut packed = Vec::with_capacity(expected_size);
    let mut new_state_map = vec![];

    packed.extend(&parents.p1);
    packed.extend(&parents.p2);

    for (filename, entry) in state_map.iter() {
        let new_filename = filename.to_owned();
        let mut new_mtime: i32 = entry.mtime;
        if entry.state == EntryState::Normal && entry.mtime == now {
            // The file was last modified "simultaneously" with the current
            // write to dirstate (i.e. within the same second for file-
            // systems with a granularity of 1 sec). This commonly happens
            // for at least a couple of files on 'update'.
            // The user could change the file without changing its size
            // within the same second. Invalidate the file's mtime in
            // dirstate, forcing future 'status' calls to compare the
            // contents of the file if the size is the same. This prevents
            // mistakenly treating such files as clean.
            new_mtime = -1;
            new_state_map.push((
                filename.to_owned(),
                DirstateEntry {
                    mtime: new_mtime,
                    ..*entry
                },
            ));
        }
        let mut new_filename = new_filename.into_vec();
        if let Some(copy) = copy_map.get(filename) {
            new_filename.push('\0' as u8);
            new_filename.extend(copy.bytes());
        }

        packed.write_u8(entry.state.into())?;
        packed.write_i32::<BigEndian>(entry.mode)?;
        packed.write_i32::<BigEndian>(entry.size)?;
        packed.write_i32::<BigEndian>(new_mtime)?;
        packed.write_i32::<BigEndian>(new_filename.len() as i32)?;
        packed.extend(new_filename)
    }

    if packed.len() != expected_size {
        return Err(DirstatePackError::BadSize(expected_size, packed.len()));
    }

    state_map.extend(new_state_map);

    Ok(packed)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{utils::hg_path::HgPathBuf, FastHashMap};

    #[test]
    fn test_pack_dirstate_empty() {
        let mut state_map: StateMap = FastHashMap::default();
        let copymap = FastHashMap::default();
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let expected = b"1234567891011121314100000000000000000000".to_vec();

        assert_eq!(
            expected,
            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
        );

        assert!(state_map.is_empty())
    }
    #[test]
    fn test_pack_dirstate_one_entry() {
        let expected_state_map: StateMap = [(
            HgPathBuf::from_bytes(b"f1"),
            DirstateEntry {
                state: EntryState::Normal,
                mode: 0o644,
                size: 0,
                mtime: 791231220,
            },
        )]
        .iter()
        .cloned()
        .collect();
        let mut state_map = expected_state_map.clone();

        let copymap = FastHashMap::default();
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let expected = [
            49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50, 49,
            51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
            48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0, 0, 0, 0, 47,
            41, 58, 244, 0, 0, 0, 2, 102, 49,
        ]
        .to_vec();

        assert_eq!(
            expected,
            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
        );

        assert_eq!(expected_state_map, state_map);
    }
    #[test]
    fn test_pack_dirstate_one_entry_with_copy() {
        let expected_state_map: StateMap = [(
            HgPathBuf::from_bytes(b"f1"),
            DirstateEntry {
                state: EntryState::Normal,
                mode: 0o644,
                size: 0,
                mtime: 791231220,
            },
        )]
        .iter()
        .cloned()
        .collect();
        let mut state_map = expected_state_map.clone();
        let mut copymap = FastHashMap::default();
        copymap.insert(
            HgPathBuf::from_bytes(b"f1"),
            HgPathBuf::from_bytes(b"copyname"),
        );
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let expected = [
            49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50, 49,
            51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
            48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0, 0, 0, 0, 47,
            41, 58, 244, 0, 0, 0, 11, 102, 49, 0, 99, 111, 112, 121, 110, 97,
            109, 101,
        ]
        .to_vec();

        assert_eq!(
            expected,
            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
        );
        assert_eq!(expected_state_map, state_map);
    }

    #[test]
    fn test_parse_pack_one_entry_with_copy() {
        let mut state_map: StateMap = [(
            HgPathBuf::from_bytes(b"f1"),
            DirstateEntry {
                state: EntryState::Normal,
                mode: 0o644,
                size: 0,
                mtime: 791231220,
            },
        )]
        .iter()
        .cloned()
        .collect();
        let mut copymap = FastHashMap::default();
        copymap.insert(
            HgPathBuf::from_bytes(b"f1"),
            HgPathBuf::from_bytes(b"copyname"),
        );
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let result =
            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                .unwrap();

        let mut new_state_map: StateMap = FastHashMap::default();
        let mut new_copy_map: CopyMap = FastHashMap::default();
        let new_parents = parse_dirstate(
            &mut new_state_map,
            &mut new_copy_map,
            result.as_slice(),
        )
        .unwrap();
        assert_eq!(
            (parents, state_map, copymap),
            (new_parents, new_state_map, new_copy_map)
        )
    }

    #[test]
    fn test_parse_pack_multiple_entries_with_copy() {
        let mut state_map: StateMap = [
            (
                HgPathBuf::from_bytes(b"f1"),
                DirstateEntry {
                    state: EntryState::Normal,
                    mode: 0o644,
                    size: 0,
                    mtime: 791231220,
                },
            ),
            (
                HgPathBuf::from_bytes(b"f2"),
                DirstateEntry {
                    state: EntryState::Merged,
                    mode: 0o777,
                    size: 1000,
                    mtime: 791231220,
                },
            ),
            (
                HgPathBuf::from_bytes(b"f3"),
                DirstateEntry {
                    state: EntryState::Removed,
                    mode: 0o644,
                    size: 234553,
                    mtime: 791231220,
                },
            ),
            (
                HgPathBuf::from_bytes(b"f4\xF6"),
                DirstateEntry {
                    state: EntryState::Added,
                    mode: 0o644,
                    size: -1,
                    mtime: -1,
                },
            ),
        ]
        .iter()
        .cloned()
        .collect();
        let mut copymap = FastHashMap::default();
        copymap.insert(
            HgPathBuf::from_bytes(b"f1"),
            HgPathBuf::from_bytes(b"copyname"),
        );
        copymap.insert(
            HgPathBuf::from_bytes(b"f4\xF6"),
            HgPathBuf::from_bytes(b"copyname2"),
        );
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let result =
            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                .unwrap();

        let mut new_state_map: StateMap = FastHashMap::default();
        let mut new_copy_map: CopyMap = FastHashMap::default();
        let new_parents = parse_dirstate(
            &mut new_state_map,
            &mut new_copy_map,
            result.as_slice(),
        )
        .unwrap();
        assert_eq!(
            (parents, state_map, copymap),
            (new_parents, new_state_map, new_copy_map)
        )
    }

    #[test]
    /// https://www.mercurial-scm.org/repo/hg/rev/af3f26b6bba4
    fn test_parse_pack_one_entry_with_copy_and_time_conflict() {
        let mut state_map: StateMap = [(
            HgPathBuf::from_bytes(b"f1"),
            DirstateEntry {
                state: EntryState::Normal,
                mode: 0o644,
                size: 0,
                mtime: 15000000,
            },
        )]
        .iter()
        .cloned()
        .collect();
        let mut copymap = FastHashMap::default();
        copymap.insert(
            HgPathBuf::from_bytes(b"f1"),
            HgPathBuf::from_bytes(b"copyname"),
        );
        let parents = DirstateParents {
            p1: *b"12345678910111213141",
            p2: *b"00000000000000000000",
        };
        let now = Duration::new(15000000, 0);
        let result =
            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                .unwrap();

        let mut new_state_map: StateMap = FastHashMap::default();
        let mut new_copy_map: CopyMap = FastHashMap::default();
        let new_parents = parse_dirstate(
            &mut new_state_map,
            &mut new_copy_map,
            result.as_slice(),
        )
        .unwrap();

        assert_eq!(
            (
                parents,
                [(
                    HgPathBuf::from_bytes(b"f1"),
                    DirstateEntry {
                        state: EntryState::Normal,
                        mode: 0o644,
                        size: 0,
                        mtime: -1
                    }
                )]
                .iter()
                .cloned()
                .collect::<StateMap>(),
                copymap,
            ),
            (new_parents, new_state_map, new_copy_map)
        )
    }
}