use crate::{    loose,    tree::{traverse::Context, Tree},};use git_features::progress::{self, Progress};use std::{convert::TryInto, io, sync::atomic::AtomicBool}; mod encode;mod error;pub use error::Error; pub(crate) struct TreeEntry {    pub id: git_hash::ObjectId,    pub crc32: u32,} impl Default for TreeEntry {    fn default() -> Self {        TreeEntry {            id: git_hash::ObjectId::null_sha1(),            crc32: 0,        }    }} /// Information gathered while executing [`write_data_iter_to_stream()`][crate::index::File::write_data_iter_to_stream]#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone)]#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]pub struct Outcome {    /// The version of the verified index    pub index_kind: crate::index::Version,    /// The verified checksum of the verified index    pub index_hash: git_hash::ObjectId,     /// The hash of the '.pack' file, also found in its trailing bytes    pub data_hash: git_hash::ObjectId,    /// The amount of objects that were verified, always the amount of objects in the pack.    pub num_objects: u32,} /// Various ways of writing an index file from pack entriesimpl crate::index::File {    /// Write information about `entries` as obtained from a pack data file into a pack index file via the `out` stream.    /// The resolver produced by `make_resolver` must resolve pack entries from the same pack data file that produced the    /// `entries` iterator.    ///    /// `kind` is the version of pack index to produce, use [`crate::index::Version::default()`] if in doubt.    /// `tread_limit` is used for a parallel tree traversal for obtaining object hashes with optimal performance.    /// `root_progress` is the top-level progress to stay informed about the progress of this potentially long-running    /// computation.    ///    /// # Remarks    ///    /// * neither in-pack nor out-of-pack Ref Deltas are supported here, these must have been resolved beforehand.    /// * `make_resolver()` will only be called after the iterator stopped returning elements and produces a function that    /// provides all bytes belonging to a pack entry writing them to the given mutable output `Vec`.    /// It should return `None` if the entry cannot be resolved from the pack that produced the `entries` iterator, causing    /// the write operation to fail.    pub fn write_data_iter_to_stream<F, F2>(        kind: crate::index::Version,        make_resolver: F,        entries: impl Iterator<Item = Result<crate::data::input::Entry, crate::data::input::Error>>,        thread_limit: Option<usize>,        mut root_progress: impl Progress,        out: impl io::Write,        should_interrupt: &AtomicBool,    ) -> Result<Outcome, Error>    where        F: FnOnce() -> io::Result<F2>,        F2: for<'r> Fn(crate::data::EntryRange, &'r mut Vec<u8>) -> Option<()> + Send + Sync,    {        if kind != crate::index::Version::default() {            return Err(Error::Unsupported(kind));        }        let mut num_objects: usize = 0;        let mut bytes_to_process = 0u64;        let mut last_seen_trailer = None;        let mut last_base_index = None;        let anticipated_num_objects = entries.size_hint().0;        let mut tree = Tree::with_capacity(anticipated_num_objects)?;        let indexing_start = std::time::Instant::now();         root_progress.init(Some(4), progress::steps());        let mut objects_progress = root_progress.add_child("indexing");        objects_progress.init(entries.size_hint().1, progress::count("objects"));        let mut decompressed_progress = root_progress.add_child("decompressing");        decompressed_progress.init(None, progress::bytes());        let mut pack_entries_end: u64 = 0;         for (eid, entry) in entries.enumerate() {            let crate::data::input::Entry {                header,                pack_offset,                crc32,                header_size,                compressed: _,                compressed_size,                decompressed_size,                trailer,            } = entry?;             bytes_to_process += decompressed_size;            decompressed_progress.inc_by(decompressed_size as usize);             let entry_len = header_size as u64 + compressed_size;            pack_entries_end = pack_offset + entry_len;             let crc32 = crc32.expect("crc32 to be computed by the iterator. Caller assures correct configuration.");             use crate::data::entry::Header::*;            match header {                Tree | Blob | Commit | Tag => {                    last_base_index = Some(eid);                    tree.add_root(                        pack_offset,                        TreeEntry {                            id: git_hash::ObjectId::null_sha1(),                            crc32,                        },                    )?;                }                RefDelta { .. } => return Err(Error::IteratorInvariantNoRefDelta),                OfsDelta { base_distance } => {                    let base_pack_offset =                        crate::data::entry::Header::verified_base_pack_offset(pack_offset, base_distance).ok_or(                            Error::IteratorInvariantBaseOffset {                                pack_offset,                                distance: base_distance,                            },                        )?;                    tree.add_child(                        base_pack_offset,                        pack_offset,                        TreeEntry {                            id: git_hash::ObjectId::null_sha1(),                            crc32,                        },                    )?;                }            };            last_seen_trailer = trailer;            num_objects += 1;            objects_progress.inc();        }        if num_objects != anticipated_num_objects {            objects_progress.info(format!(                "{} objects where resolved into {} objects during thin-pack resolution",                anticipated_num_objects, num_objects            ));        }        let num_objects: u32 = num_objects            .try_into()            .map_err(|_| Error::IteratorInvariantTooManyObjects(num_objects))?;        last_base_index.ok_or(Error::IteratorInvariantBasesPresent)?;         objects_progress.show_throughput(indexing_start);        decompressed_progress.show_throughput(indexing_start);        drop(objects_progress);        drop(decompressed_progress);         root_progress.inc();         let resolver = make_resolver()?;        let sorted_pack_offsets_by_oid = {            let in_parallel_if_pack_is_big_enough = || bytes_to_process > 5_000_000;            let mut items = tree.traverse(                in_parallel_if_pack_is_big_enough,                resolver,                root_progress.add_child("Resolving"),                root_progress.add_child("Decoding"),                thread_limit,                should_interrupt,                pack_entries_end,                || (),                |data,                 _progress,                 Context {                     entry,                     decompressed: bytes,                     ..                 }| {                    modify_base(data, entry, bytes, kind.hash());                    Ok::<_, Error>(())                },            )?;            root_progress.inc();             {                let _progress = root_progress.add_child("sorting by id");                items.make_contiguous().sort_by_key(|e| e.data.id);            }             root_progress.inc();            items        };         let pack_hash = last_seen_trailer.ok_or(Error::IteratorInvariantTrailer)?;        let index_hash = encode::write_to(            out,            sorted_pack_offsets_by_oid,            &pack_hash,            kind,            root_progress.add_child("writing index file"),        )?;        root_progress.show_throughput_with(            indexing_start,            num_objects as usize,            progress::count("objects").expect("unit always set"),        );        Ok(Outcome {            index_kind: kind,            index_hash,            data_hash: pack_hash,            num_objects,        })    }} fn modify_base(    entry: &mut crate::index::write::TreeEntry,    pack_entry: &crate::data::Entry,    decompressed: &[u8],    hash: git_hash::Kind,) {    fn compute_hash(kind: git_object::Kind, bytes: &[u8], hash_kind: git_hash::Kind) -> git_hash::ObjectId {        let mut write = git_features::hash::Write::new(io::sink(), hash_kind);        loose::object::header::encode(kind, bytes.len() as u64, &mut write)            .expect("write to sink and hash cannot fail");        write.hash.update(bytes);        git_hash::ObjectId::from(write.hash.digest())    }     let object_kind = pack_entry.header.as_kind().expect("base object as source of iteration");    let id = compute_hash(object_kind, decompressed, hash);    entry.id = id;}