comparison rust/hg-core/src/revlog/index.rs @ 45601:900b9b79b99c

hg-core: make `Index` owner of its bytes (D8958#inline-14994 followup 1/2)

Prevent building `Index` every time it is needed. It was a bad idea anyway.

When `Index::new` will return `Result` it will avoid things like `Revlog::len`
returning `Result<usize>` instead of `usize`.

[X] make `Index` owner of its bytes
[ ] make `Index::new` return an error if `offset != bytes.len()`

Differential Revision: https://phab.mercurial-scm.org/D9106

45600:b68b19104d16

use byteorder::{BigEndian, ByteOrder};

use crate::revlog::{Revision, NULL_REVISION};

pub const INDEX_ENTRY_SIZE: usize = 64;

/// A Revlog index
#[derive(Debug)]
pub struct Index<'a> {
    bytes: &'a [u8],
    /// Offsets of starts of index blocks.
    /// Only needed when the index is interleaved with data.
    offsets: Option<Vec<usize>>,
}

impl<'a> Index<'a> {
    /// Create an index from bytes.
    /// Calculate the start of each entry when is_inline is true.
    pub fn new(bytes: &'a [u8], is_inline: bool) -> Self {
        if is_inline {
            let mut offset: usize = 0;
            let mut offsets = Vec::new();

            while offset + INDEX_ENTRY_SIZE <= bytes.len() {
                offsets.push(offset);

            Self {
                bytes,
                offsets: None,
            }
        }
    }

    /// Return number of entries of the revlog index.
    pub fn len(&self) -> usize {
        if let Some(offsets) = &self.offsets {

    ///
    /// Currently, SHA-1 is used and only the first 20 bytes of this field
    /// are used.
    pub fn hash(&self) -> &[u8] {
        &self.bytes[32..52]
    }
}

#[cfg(test)]
mod tests {

            bytes
        }
    }

    #[test]
    fn test_offset() {
        let bytes = IndexEntryBuilder::new().with_offset(1).build();
        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,

45601:900b9b79b99c

use std::ops::Deref;

use byteorder::{BigEndian, ByteOrder};

use crate::revlog::{Revision, NULL_REVISION};

pub const INDEX_ENTRY_SIZE: usize = 64;

/// A Revlog index
pub struct Index {
    bytes: Box<dyn Deref<Target = [u8]> + Send>,
    /// Offsets of starts of index blocks.
    /// Only needed when the index is interleaved with data.
    offsets: Option<Vec<usize>>,
}

impl Index {
    /// Create an index from bytes.
    /// Calculate the start of each entry when is_inline is true.
    pub fn new(bytes: Box<dyn Deref<Target = [u8]> + Send>) -> Self {
        if is_inline(&bytes) {
            let mut offset: usize = 0;
            let mut offsets = Vec::new();

            while offset + INDEX_ENTRY_SIZE <= bytes.len() {
                offsets.push(offset);

            Self {
                bytes,
                offsets: None,
            }
        }
    }

    /// Value of the inline flag.
    pub fn is_inline(&self) -> bool {
        is_inline(&self.bytes)
    }

    /// Return a slice of bytes if `revlog` is inline. Panic if not.
    pub fn data(&self, start: usize, end: usize) -> &[u8] {
        if !self.is_inline() {
            panic!("tried to access data in the index of a revlog that is not inline");
        }
        &self.bytes[start..end]
    }

    /// Return number of entries of the revlog index.
    pub fn len(&self) -> usize {
        if let Some(offsets) = &self.offsets {

    ///
    /// Currently, SHA-1 is used and only the first 20 bytes of this field
    /// are used.
    pub fn hash(&self) -> &[u8] {
        &self.bytes[32..52]
    }
}

/// Value of the inline flag.
pub fn is_inline(index_bytes: &[u8]) -> bool {
    match &index_bytes[0..=1] {
        [0, 0] | [0, 2] => false,
        _ => true,
    }
}

#[cfg(test)]
mod tests {

            bytes
        }
    }

    #[test]
    fn is_not_inline_when_no_inline_flag_test() {
        let bytes = IndexEntryBuilder::new()
            .is_first(true)
            .with_general_delta(false)
            .with_inline(false)
            .build();

        assert_eq!(is_inline(&bytes), false)
    }

    #[test]
    fn is_inline_when_inline_flag_test() {
        let bytes = IndexEntryBuilder::new()
            .is_first(true)
            .with_general_delta(false)
            .with_inline(true)
            .build();

        assert_eq!(is_inline(&bytes), true)
    }

    #[test]
    fn is_inline_when_inline_and_generaldelta_flags_test() {
        let bytes = IndexEntryBuilder::new()
            .is_first(true)
            .with_general_delta(true)
            .with_inline(true)
            .build();

        assert_eq!(is_inline(&bytes), true)
    }

    #[test]
    fn test_offset() {
        let bytes = IndexEntryBuilder::new().with_offset(1).build();
        let entry = IndexEntry {
            bytes: &bytes,
            offset_override: None,