comparison rust/hg-core/src/dirstate_tree/on_disk.rs @ 47409:0ef8231e413f

dirstate-v2: Store a hash of ignore patterns (.hgignore)

Later, this help extend `read_dir` caching to directories that contain ignored
files (but no unknown files). Such cache must be invalidated when ignore patterns
change since a formerly-ignored file might become unknown.

This helps the default configuration of `hg status` where unknown files must
be listed, but ignored files are not.

Differential Revision: https://phab.mercurial-scm.org/D10836

47408:7954ee2d7cf7

/// Added at the start of `.hg/dirstate` when the "v2" format is used.
/// This a redundant sanity check more than an actual "magic number" since
/// `.hg/requires` already governs which format should be used.
pub const V2_FORMAT_MARKER: &[u8; 12] = b"dirstate-v2\n";

#[derive(BytesCast)]
#[repr(C)]
struct Header {
    marker: [u8; V2_FORMAT_MARKER.len()],

    parents: DirstateParents,

    root: ChildNodes,
    nodes_with_entry_count: Size,
    nodes_with_copy_source_count: Size,
}

#[derive(BytesCast)]
#[repr(C)]
pub(super) struct Node {

/// Either nothing if `start == 0`, or a `HgPath` of `len` bytes
type OptPathSlice = Slice;

/// Make sure that size-affecting changes are made knowingly
fn _static_assert_size_of() {
    let _ = std::mem::transmute::<Header, [u8; 72]>;
    let _ = std::mem::transmute::<Node, [u8; 57]>;
}

/// Unexpected file format found in `.hg/dirstate` with the "v2" format.
///

        )?),
        nodes_with_entry_count: header.nodes_with_entry_count.get(),
        nodes_with_copy_source_count: header
            .nodes_with_copy_source_count
            .get(),
    };
    let parents = Some(header.parents.clone());
    Ok((dirstate_map, parents))
}

        root,
        nodes_with_entry_count: dirstate_map.nodes_with_entry_count.into(),
        nodes_with_copy_source_count: dirstate_map
            .nodes_with_copy_source_count
            .into(),
    };
    out[..header_len].copy_from_slice(header.as_bytes());
    Ok(out)
}

47409:0ef8231e413f

/// Added at the start of `.hg/dirstate` when the "v2" format is used.
/// This a redundant sanity check more than an actual "magic number" since
/// `.hg/requires` already governs which format should be used.
pub const V2_FORMAT_MARKER: &[u8; 12] = b"dirstate-v2\n";

pub(super) const IGNORE_PATTERNS_HASH_LEN: usize = 20;
pub(super) type IgnorePatternsHash = [u8; IGNORE_PATTERNS_HASH_LEN];

#[derive(BytesCast)]
#[repr(C)]
struct Header {
    marker: [u8; V2_FORMAT_MARKER.len()],

    parents: DirstateParents,

    root: ChildNodes,
    nodes_with_entry_count: Size,
    nodes_with_copy_source_count: Size,

    /// If non-zero, a hash of ignore files that were used for some previous
    /// run of the `status` algorithm.
    ///
    /// We define:
    ///
    /// * "Root" ignore files are `.hgignore` at the root of the repository if
    ///   it exists, and files from `ui.ignore.*` config. This set of files is
    ///   then sorted by the string representation of their path.
    /// * The "expanded contents" of an ignore files is the byte string made
    ///   by concatenating its contents with the "expanded contents" of other
    ///   files included with `include:` or `subinclude:` files, in inclusion
    ///   order. This definition is recursive, as included files can
    ///   themselves include more files.
    ///
    /// This hash is defined as the SHA-1 of the concatenation (in sorted
    /// order) of the "expanded contents" of each "root" ignore file.
    /// (Note that computing this does not require actually concatenating byte
    /// strings into contiguous memory, instead SHA-1 hashing can be done
    /// incrementally.)
    ignore_patterns_hash: IgnorePatternsHash,
}

#[derive(BytesCast)]
#[repr(C)]
pub(super) struct Node {

/// Either nothing if `start == 0`, or a `HgPath` of `len` bytes
type OptPathSlice = Slice;

/// Make sure that size-affecting changes are made knowingly
fn _static_assert_size_of() {
    let _ = std::mem::transmute::<Header, [u8; 92]>;
    let _ = std::mem::transmute::<Node, [u8; 57]>;
}

/// Unexpected file format found in `.hg/dirstate` with the "v2" format.
///

        )?),
        nodes_with_entry_count: header.nodes_with_entry_count.get(),
        nodes_with_copy_source_count: header
            .nodes_with_copy_source_count
            .get(),
        ignore_patterns_hash: header.ignore_patterns_hash,
    };
    let parents = Some(header.parents.clone());
    Ok((dirstate_map, parents))
}

        root,
        nodes_with_entry_count: dirstate_map.nodes_with_entry_count.into(),
        nodes_with_copy_source_count: dirstate_map
            .nodes_with_copy_source_count
            .into(),
        ignore_patterns_hash: dirstate_map.ignore_patterns_hash,
    };
    out[..header_len].copy_from_slice(header.as_bytes());
    Ok(out)
}